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  • 1995-1999  (2,263)
  • 1995  (2,263)
  • Life and Medical Sciences  (2,263)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 214-218 
    ISSN: 0897-3806
    Keywords: splenie artery ; tortuosity ; celiac angiography ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Arantius (1571) was the first to describe tortuosity of the splenic artery. The present study investigated the variations in its tortuosity in man, and possible relationships with age, sex, and presence of atheroma.Twenty-nine cadaveric specimens and forty-four celiac angiograms were studied. The straight distance from the origin of the splenic artery, from the celiac trunk, to the point of commencement of the hilar branches was measured, as was the total length of the artery between these two points. The ratio of these two measurements is called the “index of tortuosity.” The cadaveric arteries were then opened and graded for the presence of atheroma on a scale of 0 to 3.Marked variation in the index was found in both the cadavers and the angiograms. No definite relationship was found with sex. However, there was a suggestion of increasing tortuosity with age, although in one 10-year-old girl, marked tortuosity was demonstrated on angiography. No significant correlation was shown between increased tortuosity and the extent of atheroma.At present, there is apparently no satisfactory explanation for tortuosity of the splenic artery. © 1995 WiIey-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 222-226 
    ISSN: 0897-3806
    Keywords: arterial embolism ; developmental anomalies ; thoracic outlet syndrome ; thrombolysis ; urokinase ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Thoracic outlet syndrome (TOS) represents a constellation of symptoms arising from the compression of the neurovascular bundle as it exits the thorax. We report a unique case of multiple rare anatomical anomalies resulting in TOS manifested by distal arterial embolism. These anomalies include the combination of: (1) a unilateral right cervical rib, Gruber's type II (Gruber 1869), (2) nonunion of the first thoracic rib, (3) abnormal fibrous insertions of the anterior scalene muscle onto the epineurium of the brachial plexus and adventitia of the subclavian artery, (4) anterior position of the brachial plexus in relation to the third portion of the subclavian artery, and (5) the bifurcation of a single root of the phrenic nerve at the level of the anterior scalene muscle. This series of findings suggest an underlying developmental abnormality with a delayed onset of symptomatology consisting of the thoracic outlet syndrome. © 1995 WiIey-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 238-238 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995) 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 17-24 
    ISSN: 0897-3806
    Keywords: sectional anatomy ; computed tomography ; magnetic resonance imaging ; pelvic connective tissu ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The sectional anatomy of the pelvic connective tissue was studied in plastinated sections of fetal and adult pelves, by computed tomography and by magnetic resonance imaging. The comparative study of the different specimens shows that the pelvic connective tissue consists of three compartments: a presacral compartment, a perirectal compartment, and a paravisceral compartment. The content and the borders of the compartments are described. Furthermore the pelvic fasciae and the pelvic ligaments are studied within the different specimens. A thin pelvic visceral fascia can only be found around the perirectal compartment. In tomographical anatomy the so called supportive ligaments of the uterus are only composed of the round ligaments and the sacrouterine ligaments. © 1995 WiIey-Liss, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 29-32 
    ISSN: 0897-3806
    Keywords: ultrasonography ; choroid plexus ; fetu ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Echogenicity of the normal fetal telencephalic choroid plexus was characterized anatomically in 102 consecutive antenatal abdominal ultrasonographic examinations. Echogenicity of the plexus was observed only during the second trimester, first appearing at week 13 and disappearing after week 23. We suggest that this echogenicity may be due to different stages of glycogen chemistry in the plexus. The knowledge that telencephalic echogenicity is confined to the second trimester should help detect diseases that cause focal areas of echogenicity in fetal life. © 1995 WiIey-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 33-35 
    ISSN: 0897-3806
    Keywords: thyroid gland ; isthmus ; pyramidal lobe ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Four developmental anomalies of the thyroid gland are to be noted: a pyramidal lobe, failure of the lobes of thyroid tissue to develop, failure of the isthmus to fuse, and absence of a significant part of the lateral lobes. We encountered failure of the isthmus to fuse in the midline of the thyroid gland in a 48-year-old female cadaver. © 1995 WiIey-Liss, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 56-60 
    ISSN: 0897-3806
    Keywords: abdomen ; anatomy ; fascial plane ; CT ; edema ; sacral ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Sacral edema is a widely recognized clinical sign. Hitherto there has been no method of radiological confirmation, nor has the anatomy of this sign been well described. In a prospective study of 100 patients referred for abdominopelvic computed tomography (CT), 17 showed radiological evidence of sacral edema. It was demonstrated clinically in 12 of these 17 patients, leaving five patients with apparent CT evidence of sacral edema in whom this was not demonstrated clinically. In two patients with clinical evidence of sacral edema, their tissue planes in this region appeared normal on CT. The edema fluid accumulates in an intermediate plane of fibrous tissue within the subcutaneous fatty layer of the trunk. In those 17 patients with CT evidence of edema, the center of the fluid accumulation was situated over the lumbar rather than the sacral spine, suggesting that the term “sacral” edema is something of a misnomer. © 1995 WiIey-Liss, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 102-109 
    ISSN: 0897-3806
    Keywords: collagen fibers ; elastic-elastic-related fibers ; omentun minus ; mesoscopy ; first duodenal sphincter ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morpho-functional relationships between the hepato-duodenal ligament and the superior part of the duodenum are analysed. Twenty-four specimens were removed during necropsies of adults and prepared according to various mesoscopic, microscopic, and ultramicroscopical methods, i. e., whole-mounts, membrane preparations, thick and thin histological sections, and polarized light, scanning, and transmission electron microscopy were employed.The hepato-duodenal ligament is formed by longitudinally elongated, type I collagen fiber bundles which are interlinked by more delicate bundles of type III collagen fibers. Longitudinally disposed elastic fibers are the principal component of the elastic fiber system of the ligament. These are in continuity with the elaunin and oxytalan fibers which are intermingled with the muscle cells of the vessels and duodenal wall, and fat cells of the ligament.Part of the muscle bundles of the external, longitudinal, muscle layer of the Cluodenum is anchored in the adventitial and subserosal collagen and elastic fiber framework of the organ while part inserts directly into the fibrous framework of the ligament. The fibrous system of the ligament is continuous with that of the subserosa and adventitia of the duodenum. © 1995 WiIey-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 110-115 
    ISSN: 0897-3806
    Keywords: pudendal nerve ; sacral nerve roots ; continence ; incontinence ; pudendal canal syndrome ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A study of the surgical anatomy of the pudendal nerve (PN) was performed in 13 female and 7 male cadavers. The knowledge of the precise anatomy and anomalies of this important nerve would help in better localization of the nerve and its roots and branches for neurostimulation or for pudendal canal decompression in pudendal canal syndrome. Two routes were used in the dissection: gluteal and perineal. The PN was identified and its course was followed from its roots to its termination.The PN was composed of three roots derived from the 2nd, 3rd, and 4th anterior sacral rami (S 2,3,4). The roots received a contribution from S 1 in five cadavers and from S 5 in one. The three roots formed two cords. The first root continued as the upper cord while the second and third root fused together producing the lower cord. The PN was formed by union of the two cords a short distance proximal to the sacrospinous ligament, and then crossed the back of the ligament. In no specimen did the nerve cross the ischial spine.The inferior rectal nerve arose from the PN in the pudendal canal in 18 cadavers. In two cases it came out proximal to the canal; this would spare the two subjects the anorectal manifestations of the pudendal canal syndrome. As the PN crossed the back of the sacrospinous ligament, it gave origin to a branch that supplied the levator ani muscle. This branch was only found in male cadavers and we call it “accessory rectal nerve”; the levator ani muscle in such cadavers was doubly innervated on its perineal aspect. © 1995 WiIey-Liss, Inc.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 134-138 
    ISSN: 0897-3806
    Keywords: Vesalius ; Fabrica ; translation ; teeth ; history of medicine ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An annotated translation into English of Chapter 11, Book One, “On the Teeth, Which Are Also Counted as Bones,” from Andreas Vesalius' De humani corporis fabrica. The translation incorporates the text of both the 1543 and 1555 editions, and verified citations of ancient sources. In this chapter, Vesalius corrects errors of Galen and demonstrates and describes for the first time the anatomy and function of the dental pulp cavity. © 1995 WiIey-Liss, Inc.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 148-153 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 154-161 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 208-213 
    ISSN: 0897-3806
    Keywords: ligament ; joint capsule ; vein ; temporomandibular joint ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In the human temporomandibular joints of 14 Japanese cadavers, we observed a new retinacular ligament that connected to the retrodiskal pad posterolaterally and was accompanied by a vein draining the retrodiskal pad. This retinacular ligament originated from lateral to posterolateral part of the joint. The origin included the articular tubercle of the zygomatic process of the temporal bone. The ligament descended along the mandibular ramus to insert into the fascia of the masseter muscle at the mandibular angle. The vein originated from the venous plexus in the retrodiskal pad and ran parallel to the retinacular ligament, giving off branches to the retromandibular, transverse facial, and superfacial temporal veins. There were no remarkable differences in the size of the retinacular ligaments among individuals as well as between the left and right sides. The retinacular ligament had firm fibrous connections with the posterolateral part of the retrodiskal pad, where the external fibrous membrane of the articular capsule was lacking. These findings suggest that the retinacular ligament and its accompanying vein function together to maintain blood circulation during jaw movement and may also be related to the development of occlusal disorders. © 1995 WiIey-Liss, Inc.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 227-230 
    ISSN: 0897-3806
    Keywords: tumor ; etiological factors ; presacral embryology ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A case report involving a 42-year-old female is presented. The symptoms and objective physical findings manifest a diagnostic problem. The anatomical site of the tumor depends on the consideration of the numerous possible etiological factors, and one of which is the embryologic knowledge of the region involved. The clinical, pathological, and embryologic features of a case of presacral tumor is presented. © 1995 WiIey-Liss, Inc.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 219-221 
    ISSN: 0897-3806
    Keywords: splenic artery ; tortuosity ; primates ; pig ; greyhound ; human ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The splenic artery of four mammals-pig, greyhound, rhesus macaque, and olive baboon-was studied to determine its tortuosity and pattern of convolutions. The results were compared to those previously gathered in humans. It was found that the isolated cadaveric arteries showed a noticeable species variation in mean index of tortuosity. In the pig and dog, the artery was nearly straight throughout its length, with a very low index of tortuosity, not significantly different in the two species (P 〉0.1). The artery was significantly more tortuous in the rhesus macaque and baboon than in both pig and dog, (Ps 〈 0.001), with a single large convolution present in the proximal one-third. In humans, the artery is commonly tortuous throughout its length and is significantly more tortuous than in the pig and dog (P 〈 0.001), but not significantly more tortuous than in the baboon (P 〉 0.1) and only just significantly more so than in the rhesus macaque (0.02 〈 P 〉 0.05). The speculation that the tortuosity of the artery may be related to habitual posture, being less in the pronograde pig and dog than in the partly orthograde rhesus macaque and baboon, is not supported by results in the wholly orthograde human. © 1995 WiIey-Liss, Inc.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 256-261 
    ISSN: 0897-3806
    Keywords: anatomical features of left main bronchus ; absence of pulmonary artery flow ; flow ; retrograde filling of pulmonary artery ; broncho-pulmonary shunt ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This explanation of the previously described left bronchus syndrome (Ashour et al., 1990, Thorax, 45:210-212) is based on a prospective study of 17 additional cases with unilateral lung destruction. It is likely that the anatomic peculiarities of the left main bronchus predispose the left lung to more frequent bronchial obstruction and hemodynamic changes than the right. Broncho-pulmonary shunt formation and retrograde filling of the pulmonary artery most likely lead to increased oxygen tension and impaired lymph flow in the entire lung, thus spreading tuberculosis in the lung and ultimately leading to left lung destruction. © 1995 WiIey-Liss, Inc.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 366-366 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 19
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 347-351 
    ISSN: 0897-3806
    Keywords: spinal cord ; vascular resistance ; postoperative paraplegia ; anatomy ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We studied the anterior spinal artery (ASA) in 25 cadaveric human spinal cords to determine the cross-sectional area of the ASA cephalad and caudal to the entry of the arteria medullaris magna anterior (AMMA). Spinal cords were removed en bloc and latex was injected into the AMMA. The preparations were then fixed in formalin, embedded in paraffin, sectioned, mounted, and stained with hematoxylin and eosin. The diameter and cross-sectional area of the ASA 1 cm above and 1 cm below the entry of the AMMA were measured. The mean radius of the ASA above the entry of AMMA was 0.14 ± 0.03 mm compared to 0.28 ± 0.05 mm below the entry of the AMMA (P 〈 0.001). According to Poiseuille's equation, the resistance to blood flow in the ASA cephalad to the AMMA would be 14.8 times greater than the resistance to blood flow caudal to the ANIMA. This resistance could affect the distribution of blood flow in the distal spinal cord whenever flow in the AMMA or distal ASA is altered. © 1995 WiIey-Liss, Inc.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 363-365 
    ISSN: 0897-3806
    Keywords: dissection ; brain ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The brain was removed from cadavers using a modified technique involving additionally the removal of most of the squamous occipital bone and laminae of the upper cervical vertebrae. The resulting specimens were superior to the usual ones in that the medulla oblongata, the upper spinal cord, and all the cranial nerves and cerebral arteries were intact. Fears of slow-virus contamination and legislative changes are precluding the use of brains obtained in the necropsy room for neuroanatomy teaching, so it is paramount that complete brains are removed from dissecting room cadavers. The method described herein takes a little longer than the traditional method, but is within the capability of an anatomy technician and yields better specimens for use in teaching and examinations. © 1995 WiIey-Liss, Inc.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 377-377 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 23
    ISSN: 0897-3806
    Keywords: human gross anatomy ; cadaver ; anatomical variability ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: One way to increase medical students' awareness of anatomical variability is the dissection of different cadavers throughout laboratory coursework. This report covers such a procedure successfully instituted in a human gross anatomy course. © 1995 WiIey-Liss, Inc.
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  • 24
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 436-437 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 25
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 443-444 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 26
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 434-435 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 27
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 440-440 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 28
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 235-236 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 29
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 237-237 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 30
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 327-333 
    ISSN: 0897-3806
    Keywords: cartilage ; joint ; larynx ; nerve compression ; posterior cricoarytenoid muscle ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The posterior cricothyroid ligament and its topographic relation to the inferior laryngeal nerve were studied in 54 human adult male and female larynges. Fourteen specimens were impregnated with curable polymers and cut into 600-800 μm sections along different planes. Forty formalin-fixed hemi-larynges were dissected and various measurements were made. The posterior cricothyroid ligament provides a dorsal strengthening for the joint capsule of the cricothyroid joint. Its fibers spread in a fan-like manner from a small area of origin at the cricoid cartilage to a more extended area of attachment at the inferior thyroid cornu. The ligament consists of one (7.5%) to four (12.5%), in most cases of three (45.0%) or two (35.0%), individual parts oriented from mediocranial to latero-caudal. The inferior laryngeal nerve courses immediately dorsal to the ligament. In 60% it is covered by fibers of the posterior cricoarytenoid muscle, in the remaining 40% it is not. In this latter topographic situation there is almost no soft tissue interposed between the nerve and the hypopharynx. Therefore, the nerve may be exposed to pressure forces exerted from dorsally. It may be pushed against the unyielding posterior cricothyroid ligament and suffer functional or structural impairment. Probably, this mechanism may explain some of the laryngeal nerve lesions described in the literature after insertion of gastric tubes. © 1995 WiIey-Liss, Inc.
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  • 31
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 359-362 
    ISSN: 0897-3806
    Keywords: stylohyoid ligament ; styloid process ; styloid syndrome ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A bilateral ossified stylohyoid ligament was observed in a cadaver specimen. On the left side, the stylohyoid chain was markedly enlarged. The stylohyoid ligament was completely ossified into two segments separated by a diarthrodial-like joint. An articulation was also observed between the enlarged styloid process and the ossified ligament. On the right side, the styloid process had a normal appearance. The middle part of the stylohyoid ligament was ossified and it was attached to the styloid process and to the hyoid bone by a fibrous band. Proposed theories to account for the ossification oaf this ligament are discussed. Since the presence of an enlarged and ossified stylohyoid chain can cause much discomfort and pain, a greater understanding of the causative factors responsible for this anomaly is needed to provide for more effective diagnosis and treatment. © 1995 WiIey-Liss, Inc.
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  • 32
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    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 352-358 
    ISSN: 0897-3806
    Keywords: Frankfurt plane ; cephalometry ; morphometry ; dentistry ; man ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to assess the relationship between the hard (porion-orbitale) and soft (tragusorbitale) tissue Frankfurt planes, the relative positions of porion, orbitale, and tragus were evaluated on cephalometric radiographs. A 5-mm radiopaque disk was fixed on the right tragus of 160 white orthodontic patients (65 males aged 7 to 28 years, and 95 females aged 7 to 36 years), and a pretreatment lateral cephalometric radiograph was taken. In every film the positions of orbitale, porion, and tragus were digitized, and the linear distances between the points, as well as the position of tragus relative to the skeletal structures, were calculated. The linear distances porion-orbitale and tragus orbitale progressively increased with age, with a low variability in all age classes. The linear distances were always larger in the males than in the females. The tragus was always lower and more anterior than the porion, with vertical distances ranging from 1.2 to 19.8 mm. When the porion-tragus distance was expressed as a percentage of the porion-orbitale distance, the variability decreased. In the age classes, mean percentage horizontal projections from porion ranged from 18 to 23% of the porion-orbitale distance, mean percentage vertical projections ranged from 8 to 15%. Unfortunately, sample variability was large, and, in a single patient, the position of tragus relative to the skeletal structures could be predicted only with a large approximation. © 1995 WiIey-Liss, Inc.
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  • 33
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    Clinical Anatomy 8 (1995), S. 375-376 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 34
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    Clinical Anatomy 8 (1995) 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 35
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    Clinical Anatomy 8 (1995), S. 391-398 
    ISSN: 0897-3806
    Keywords: tendons ; extensor digitorum ; extensor digiti minimi ; extensor indicis ; back of the hand ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: One hundred eighty-one dissected hands were examined to study the pattern of extensor tendons on the dorsum of the hand. Extensor digitorum often had multiple tendons for the middle and ring fingers. Its contribution to the little finger was usually by a bifurcating tendon common with that of the ring finger. The index finger always received a single tendon. Intertendinous connections between the various tendons of the extensor digitorum were variable but were most frequent between ring and middle fingers.Extensor indicis had one tendon in most of the specimens and it was always on the ulnar side of the extensor digitorum tendon. This remained true even when there were multiple tendons.Extensor digiti minimi had two tendons in most cases. It was always linked to extensor digitorum either by receiving one or part of its tendon or by an intertendinous connection.Two accessory muscles were seen, one was extensor indicis brevis replacing the proper muscle. The other, the extensor medii brevis, was distributed to the middle finger. © 1995 WiIey-Liss, Inc.
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  • 36
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    Clinical Anatomy 8 (1995), S. 403-406 
    ISSN: 0897-3806
    Keywords: buccal fat pad ; anatomy ; pathology ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Within the cheek, wedged between masseter and buccinator, is a biconvex pad of fatty tissue, the corpus adiposum buccae, or buccal fat pad (of Bichat). It contributes significantly to the prominence of the cheek of the newborn infant and is sometimes encountered in surgical procedures in the region of the ramus of the mandible or the maxillary tuberosity.This paper reviews the history of the study of the buccal pad of fat, its anatomical location, blood supply, and comparative anatomy. We have also reviewed the pathology of the buccal pad of fat, including traumatic herniation. The fat pad is of interest surgically as it can be used as a free or pedicled graft to close maxillary defects after excision of tumors. © 1995 WiIey-Liss, Inc.
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  • 37
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    Clinical Anatomy 8 (1995), S. 418-425 
    ISSN: 0897-3806
    Keywords: embryological terminology ; mesenchyme ; early development ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The meaning of some terms used in describing the development of embryos is discussed in the light of their historical origin and current usage. Attention is focused on the terminology associated with the early development of animals, particularly that concerned with gastrulation and germ layer theory. It is suggested that terms linked with outdated concepts are not always appropriate for, and unless defined with care may limit, our appreciation of the significance of subsequent observation and experiment. Recommendations are made concerning the use of the terms mesoblast, mesoderm and mesenchyme.
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  • 38
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    Clinical Anatomy 8 (1995), S. 426-428 
    ISSN: 0897-3806
    Keywords: Nomina Anatomica (critical remarks) ; PNA 6th edition ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Attention is called to the discrepancy which exists between the official terminology of the Nomina Anatomica (PNA) as it relates to the superficial venous system of the lower limb, and anatomical reality. Suggestions are also put forward as to how the PNA could be altered to accord better with the systematic classification and topography of these vessels, and more usefully serve the needs of clinicians. © 1995 WiIey-Liss, Inc.
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  • 39
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    Clinical Anatomy 8 (1995), S. 439-439 
    ISSN: 0897-3806
    Keywords: Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 40
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    Cell Motility and the Cytoskeleton 30 (1995), S. 17-25 
    ISSN: 0886-1544
    Keywords: rotation ; twisting ; microtubule-dynein complex ; 22S dynein ; dynein-track ; ATP ; sliding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Applying a new in vitro motility assay system for microtubules and 22S dynein, we recently reported on an ATP-induced extrusion of microtubules from microtubule-dynein α- and β-complexes [Mimori and Miki-Noumura, 1994:Cell Motil. Cytoskeleton 27:180-191]. In the present study, we prepared a γ-complex by copolymerizing porcine brain tubulin and Tetrahymena ciliary 22S dynein, and examined the ATP-induced microtubule movement from the γ-complex. The extrusion process appeared quite similar to that of the β-complex. The sliding velocity was 18.39 ± 2.20 m̈m/sec, which was a value comparable to that of trypsin-digested flagellar axonemes [Yano and Miki-Noumura, 1980:J. Cell Sci. 44:169-186]. Higher velocity may be due to a densely arranged dynein-track with the same polarity, which was detached from the γ-complex and absorbed in rows on a glass surface of the slide. Sometimes a free-floating microtubule in the perfusion chamber was observed riding and sliding on the dynein-track remaining on the slide after extrusion.Unexpectedly, we found that when the front part of the microtubule was fixed to a glass surface, a continuous sliding microtubule at the rear part on the dyneintrack often transformed into a left-handed helix, and subsequently a twisted helix with several turns. The helix formation may be due to some rigidity in the microtubule and a right-handed torque component in the sliding force of 22S dynein. The addition of ATP may release some distortion accumulated in the complex structure during copolymerization of tubulin and 22S dynein, inducing reverse rotation of the microtubule. © 1995 Wiley-Liss, Inc.
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  • 41
    ISSN: 0886-1544
    Keywords: trout ; spermatozoa ; ATP ; cAMP ; axoneme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Live trout spermatozoa initiate flagellar motility for only a short period (30 sec at 18°C) during which their mean beat frequency decreases steadily from 60 to 20 Hz. Motility then stops abruptly. Investigations of the activation of movement in demembranated sperm points to cyclic-AMP being necessary for reactivation (half effect at 0.5μm) in some conditions. cAMP acts mainly by increasing the percentage of motile cells and not the beat frequency (BF) of the flagellar axoneme. Dibutyryl cAMP does not initiate movement or prolong motility of live sperm.The initiation of movement of demembranted trout sperm was investigated in various incubation conditions relative to previous phases of in vivo movement and to ATP concentration. In the absence of cAMP and in the presence of ATP lower than 25 μM, all sperm celi models were active with BF up to 15-20 Hz whatever their previous physiological condition. In contrast, at ATP concentrations above 100 μM, the fraction of active spermatozoa decreased proportionally but the BF of the active ones increased so that, at 1 mM ATP up to 20 μM restored activity to 100% sperm models with a similar BF of 65 Hz.At ATP concentrations higher than 25 μM, cAMP was necessary in a concentration dependent manner in the reactivation, but not in the demembranation meduim. This dependence was found to be unrelated to a previous in vivo phase of movement. The antagonistic effects of ATP vs. cAMP were tested at various concentrations of both nucleotides: the apparent affinity for cAMP, measured as the concentration restoring movement of 50% cell models, was decreased from 15 nM at 0.1 mM ATP to 0.5 μM at 1 mM ATP; conversely, the affinity for ATP, measured as the concentration giving rise to the half maximal beat frequency, was not significautly affected when the concentration of cAMP was raised to 0.5 mM. Preincubation with phosphodiesterase (PDE) resulted in motility of 100% of sperm models even at low ATP concentration. This tends to show that cAMP must be constantly present to sustain motility.
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  • 42
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    Cell Motility and the Cytoskeleton 31 (1995), S. 147-158 
    ISSN: 0886-1544
    Keywords: actin ; contact guidance ; microfilaments ; microtubules ; orientation ; cytochalasin ; colcemid ; taxol ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of the cytoskeleton and cell attachments in the alignment of baby hamster kidney fibroblasts to ridge and groove substratum topography was investigated using confocal scanning microscopy. This was carried out with normal cells and cells treated with the cytoskeleton modifiers cytochalasin D, colcemid, and taxol. Actin was localised with fluorescent phalloidin. Tubulin, Vinculin, and intracellular adhesion molecule-1 were visualised by indirect immunofluoresence. The spreading, elongation, and orientation of the cells after 24 h of culture in these conditions were measured on grooves of 5, 10, and 25 μm width and 0.5, 1, 2, and 5 μm depth. We have also observed events over the first 30 min of cell attachment. Five minutes after cell attachment, F-actin condensations were seen close to the intersection of groove wall and ridge top, that is, at a topographic discontinuity. The condensations were often at right angles to the groove edge and showed a periodicity of 0.6 μm. Vinculin arrangement at the early stages of cell spreading was similar to that of actin. Organisation of the microtubule system followed later, becoming obvious at about 30 min after cell plating. The Curtis and Clark theory (that cell react to topography primarily at lines of discontinuity in the substratum by actin nucleation) is supported by these results. The use of cytoskeletal poisons did not entirely abolish cell reaction to grooves. Colocemid increased cell spreading and reduced cell orientation and elongation. Cytochalasin D reduced cell spreading, orientation, and elongation. Taxol reduced cell elongation but did not affect cell spreading and orientation. We conclude that the aggregation of actin along groove/ridge boundaries is a primary driving event in determining fibroblast orientation on microgrooved substrata.
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  • 43
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    Cell Motility and the Cytoskeleton 30 (1995) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 44
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    Cell Motility and the Cytoskeleton 30 (1995), S. 108-121 
    ISSN: 0886-1544
    Keywords: intercellular junctions ; desmosome ; assembly ; kinase ; phosphatase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Desmosomes are one component of the intercellular junctional complex in epithelia. In cultures of epithelial cells, desmosome assembly can be regulated by modulating the calcium concentrations of the growth media. At present, very little is known about the intracellular signal transduction mechanisms that regulate desmosome assembly and disassembly in response to changing extracellular calcium concentrations. We have used inhibitors of protein kinases and phosphatases in a combined biochemical and morphological approach to analyze the role of protein phosphorylation in the assembly and disassembly of desmosomes in Madin-Darby canine kidney epithelial cells. Our results suggest that desmosomal proteins (desmoplakins I/II and desmoglein 1) are primarily phosphorylared on serine residues. Electron microscopic analyses of desmosome assembly upon induction of cell-cell contact, in the presence of protein kinase inhibitor, H-7, revealed an apparently normal assembly of desmosomes. However, complete disassembly of desmosomes was inhibited by H-7 upon removal of extracellular calcium. Under these conditions, although desmosomes split, desmosomal plaques and their associated cytokeratin filaments can not be internalized. In contrast, treatment of the cultures with okadaic acid (OA), an inhibitor of protein phosphatases, inhibited desmosome assembly but had no effect on disassembly. In addition, the inhibitory effect of okadaic acid on desmosome assembly was specific to this junction since we observed apparently normal tight junction and adherens junction in okadaic acid-treated cultures. These results suggest that via reversible protein phosphorylation involving both protein kinase and protein phosphatases. © 1995 Wiley-Liss, Inc.
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  • 45
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    Cell Motility and the Cytoskeleton 31 (1995), S. 196-206 
    ISSN: 0886-1544
    Keywords: gelsolin ; actin ; myofibrils ; immunofluorescence ; nebulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the binding of gelsolin to thin myofilaments in situ and their stability against severing. Differentiated myotubes from chicken skeletal muscle containing cross-striated myofibrils were permeabilized with Triton X-100 and incubated with gelsolin. Immunoflurorescence microcopy localized both endogenous and exogenous gelsolin in the I-Z-I-regions of the sarcomers. The staining pattern suggested a binding of the exogenous gelsolin along the entire length of the thin filaments. This binding was Ca2+ dependent, but gelsolin was not removed after subsequent addition of EGTA. The fluorescence staining for actin remained unchanged after gelsolin incubation, indicating that thin filaments in cross-striated myofibrils were resistant to the severing action of gelsolin, in contrast to the microfilaments in stress fibers. After extraction of the permeabilized cells with high ionic strength to remove tropomyosin and myosin, gelsolin stell bound along the entire thin filament and the actin pattern also remained unchanged. After Triton X-100 permeabilization and high ionic strength extraction, the giant protein nebulin was found to be still present as a myofibrillar component. Gelsolin treatment after high salt extraction affected neither actin nor nebulin in the thin filaments. We therefore conclude that nebulin confers the gelsolin resistance to the sarcomeric actin filaments.
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  • 46
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    Cell Motility and the Cytoskeleton 31 (1995), S. 207-214 
    ISSN: 0886-1544
    Keywords: flagella ; Chlamydomonas ; mutant ; high-frequency vibration ; nanometer-scale measurement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flageliar axoneme of the mutant pf18 lacking the central pair does not beat, but undergoes a nanometer-scale, high-frequency oscillation (hyper-oscillation) in the presence of ATP [Yagi et al., 1994: Cell Motil, Cytoskeleton 29:177-185]. The present study demonstrates that the amplitude of the hyper-oscillation increases significantly in the simultaneous presence of ATP and ADP. In addition, the hyper-oscillation under these conditions sometimes takes on an exceptionally simple asymmetric pattern, in which the maximal shearing velocity exceeds 50 μm/sec, much higher than the maximal velocity of ordinary dynein-microtubule sliding. The asymmetric oscillation thus appears to be at least partly driven by an internal elastic force. Its amplitude suggests that the axoneme has an elastic component that can be stretched by as long as 0.1 μm. Analyses of the asymmetric pattern further suggests that the axonemal dyneins have a tendency to attach to and detach from the doublets cooperatively and that the mechanochemical cycle of dynein has an inherent refractory period of about 2 msec, during which dynein cannot interact with microtubules.
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  • 47
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    Cell Motility and the Cytoskeleton 31 (1995), S. 225-240 
    ISSN: 0886-1544
    Keywords: cell-substratum adhesion ; lamellar contractility ; locomotion ; silicone rubber ; traction forces ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A means of determining quantitative maps of the tractions exerted by locomoting cells on a substratum has been developed. This method is similar to the Harris silicone substratum assay [Harris et al., 1980: Science 208:177-179], but uses an improved non-wrinkling film that deforms more predictably in response to traction forces. The method also utilizes a mathematical analysis of rubber deformation to produce the final map of the distribution of tractions. The resulting maps consistently showed that fish keratocytes exert a steady-state “pinching” on the substratum, perpendicular to the cell's direction of locomotion. No significant rearward tractions were detected at or near the front edge of the cell. Likewise, no significant forward tractions associated with peeling of adhesions were found at the back of the cell. A second assay uses deflection of a lightly attached glass microneedle to measure the total force exerted by locomoting cells. Forces of approximately 4.5 × 10-3 dyn were required to “stall” locomoting keratocytes. The implications of these findings for cell movement are discussed.
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  • 48
    ISSN: 0886-1544
    Keywords: microfilamentous cytoskeleton ; actin binding proteins ; actin polymerization ; annealing ; non-muscle cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gelsolin, a Ca++ activated, 90 kd actin binding protein, can regulate actin polymerization in polymorphonuclear leukocytes (PMNs) via severing of filaments to dissolve gels or by capping of filament ends to limit polymerization. In Triton-lysed PMNs, 30% of gelsolin is bound to the Triton-soluble F-actin (TSF) pool and none is bound to the Triton-insoluble F-actin (TIF) pool. Calcium-activated PMNs exhibit concurrent temporal and quantitative TIF growth and TSF and total F-actin loss. To determine if gelsolin plays a role in regulating TSF pool size, we monitored gelsolin-actin interactions and TIF, TSF and G-actin content at 5 second intervals in PMNs activated with the calcium ionophore, ionomycin. Actin pools were measured by NBDphallacidin binding and by gel scans and expressed relative to basal; gelsolin-actin interactions were measured as change in the amount of EGTA-resistant gelsolin:actin (G:A) complexes and by immunoblot quantification of gelsolin in actin pools. In basal PMNs, 33% of PMN gelsolin is bound in 1:1 EGTA-resistant G:A complexes and TSF and TIF retain 30% and 0% of PMN gelsolin, respectively. By 20 seconds after ionomycin addition, TSF decreases, TIF increases and a fraction of gelsolin repartitions from the TSF to the TIF pool. At maximum change (60 seconds), total F-actin (TIF + TSF) and TSF decrease and TIF increases by 25%; gelsolin is bound to both TSF and TIF (35% of total gelsolin in each pool), and 1:1 EGTA-resistant G:A complexes increase from 33% to 70%. No changes occur in cells activated by ionomycin in the absence of Ca++. The data show Ca++ activated TIF growth and TSF loss are temporally and quantitatively associated with an increase in the percent of gelsolin bound to actin and the translocation of gelsolin from TSF to TIF. This is unique, since no other PMN activator is known to repartition gelsolin into TIF actin. Further, the Ca++ activated initial increase in TIF concurrent with a fall in TSF without a change in total F-actin or G-actin content suggest that TIF grows initially only by TSF annealing/cross-linking to TIF. Gelsolin may regulate these events. © 1995 Wiley-Liss, Inc.
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  • 49
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    Cell Motility and the Cytoskeleton 30 (1995), S. 146-152 
    ISSN: 0886-1544
    Keywords: zinc-sheets ; macrotubes ; kinesin ; electron microscopy ; microtubules ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Moving along a microtubule, kinesin follows a course parallel to the protofilaments; but it is not known whether kinesin binds exclusively on a single protofilament. The presence of zinc during tubulin polymerization induces sheets where neighboring protofilaments are antiparallel. If kinesin could support the motility of these zinc-sheets, then the binding site for a kinesin molecule would be limited to a single protofilament.Kamimura and Mandelkow [1992: J. Cell Biol. 118:865-75] reported that kinesin moves along zinc-sheets. We found that zinc-sheets grown under their conditions often had a microtubule-like structure along one edge. We confirmed the possibility that the motility observed by Kamimura and Mandelkow [1992: J. Cell Biol. 118:865-75] is attributed to the microtubule-like structure rather than the zinc-sheet.To resolve the question of whether kinesin can recognize an antiparallel protofilament lattice, we investigated the kinesin-mediated motility of zinc-macrotubes. At higher free zinc concentrations, zinc-sheets roll up as macrotubes, free of edges. In the presence of 10 m̈M taxol and 100 nM free Zn2+ at pH 6.8, the samples were shown by electron microscopy to contain only macrotubes. Under these buffer conditions, kinesin could bind strongly to axonemal doublets in the presence of AMP-PNP, and generate motility in the presence of ATP, but kinesin did not bind to nor move the macrotubes. This shows that kinesin cannot bind efficiently to nor move on the anti-parallel lattice; it is possible (though not necessary) that the groove between two parallel protofilaments is required for kinesin's motility. © 1995 Wiley-Liss, Inc.
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  • 50
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    Cell Motility and the Cytoskeleton 30 (1995) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 51
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    Cell Motility and the Cytoskeleton 30 (1995), S. 153-163 
    ISSN: 0886-1544
    Keywords: colchicine binding site ; MTC ; cod microtubules ; bovine microtubules ; MAPs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Isolated microtubules from cod (Gadus morhua) are apparently more stable to colchicine than bovine microtubules. In order to further characterize this difference, the effect of the colchicine analogue 2-methoxy-5-(2,3,4-trimethoxyphenyl)-2,4,6-cyclo heptatrien-1-one (MTC) was studied on assembly, as measured by turbidity and sedimentation analysis, and on polymer morphology. MTC has the advantage to bind fast and reversible to the colchicine binding site of tubulin even at low temperatures. It was found to bind to one site in cod brain tubulin, with affinity (6.5 ± 1.5) × 105M 1at both low or high temperature, similarly to bovine brain tubulin. However, the effect of the binding differed. At substoichiometric concentrations of MTC bovine brain microtubule assembly was almost completely inhibited, while less effect was seen on the mass of polymerized cod microtubule proteins. A preformed bovine tubulin-colchicine complex inhibited the assembly of both cod and bovine microtubules at substoichiometric concentrations, but the effect on the assembly of cod microtubules was less. At higher concentrations (5 × 10-5 to 1 × 10-3M), MTC induced a large amount of cold-stable spirals of cod proteins, whereas abnormal polymers without any defined structure were formed from bovine proteins. Spirals of cod microtubule proteins were only formed in the presence of microtubule associated proteins (MAPs), indicating that the morphological effect of MTC can be modulated by MAPs. The effects of colchicine and MTC differed. At 10-5M colchicine no spirals were formed, while at 10-4M and 10-3M, a mixture of spirals and aggregates was found. The morphology of the spirals differed both from vinblastine spirals and from the spirals previously found when cod microtubule proteins polymerize in the presence of high Ca2concentrations. The present data show that even if the colchicine binding site is conserved between many different species, the bindings have different effects which seem to depend on intrinsic properties of the different tubulins. © 1995 Wiley-Liss, Inc.
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  • 52
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    Cell Motility and the Cytoskeleton 31 (1995), S. 298-306 
    ISSN: 0886-1544
    Keywords: Drosophila ; nurse cells ; oocyte ; microfilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of microfilaments in Drosophila egg chambers stained with rhodamine (Rh)-conjugated phallcidin was studied by laser scanning confocal microscopy and transmission electron microscopy. These techniques revealed new details in the pattern of microfilament localization. We observed in stage 1-3 egg chambers accumulation of filamentous actin in the oocyte cytoplasm between the ring canals connecting the oocyte with adjacent nurse cells. Starting from stages 6-7 short microfilament bundles arranged in basket-like structures were associated with the side of the ring canals facing the nurse cell cytoplasm. We also observed a dramatic decrease in the actin network associated with the cortex of the oocyte in stage 10. During stage 10B the nurse cell cytoplasm was crossed by radial actin bundles that showed a sarcomeric-like cross striation after Rh-phalloidin staining. The ring canals also did not uniformly stain but showed a punctate labeling. The implications of the actin cytoskeleton during oocyte growth are discussed. © 1995 Wiley-Liss, Inc.
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  • 53
    ISSN: 0886-1544
    Keywords: neurofilament ; phosphorylation ; cdk5 ; cdc2 ; cyclin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using dephosphorylated neurofilament (NF) proteins as substrates, the kinase with a higher activity for in the dephosphorylated NF-H than the phosphorylated form of NF-H was searched for in the porcine brain extract. Most NF-H kinase activity in the brain extract pelleted with microtubules. The NF-H kinase purified from a high salt extract of the microtubule pellets was composed of cdk5 and a 26 kDa protein, a fragment of the 35 kDa regulatory subunit of cdk5. In contrast to the association of the active kinase with microtubules, each of uncomplexed cdk5 and the 35 kDa regulatory subunit was differently distributed in the supernatant fraction and the pellet, respectively, by ultracentrifugation of the brain extract. Dephosphorylated forms of NF-H and NF-M became reactive to antibodies recoginizing in vivo phosphorylation sites (SM131, 34, and 36, JJ31 and 51) by phosphorylation with cdk5/p26. cdk5/p26 showed similar enzymatic properties to p34cdc2/cyclin B kinase; the substrate specificity and inhibition by a p34cdc2 kinase specific inhibitor, butyrolactone I. However, p34cdc2/cyclin B kinase was distinguished from cdk5/p26 by its binding to p13suc1 protein and by its reactivity to anti-p34cdc2 antibodies. In spite of similar enzymatic properties of cdk5/p26 and p34cdc2/cyclin B kinase, cdk5/26 did not display M-phase promoting activity when assayed with a cell-free system of Xenopus egg extract. © 1995 Wiley-Liss, Inc.
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  • 54
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    Cell Motility and the Cytoskeleton 32 (1995), S. 133-135 
    ISSN: 0886-1544
    Keywords: cytoplasmic dynein ; motor domain ; mutational analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The highly conserved lysine residue in the putative hydrolytic ATP-binding motif of the yeast cytoplasmic dynein heavy chain was replaced with leucine. The mutation was generated by a two-stage transformation method designed for genomic site-directed mutagenesis. Preliminary observations show that the effects of this alteration on the cellular roles of dynein are indistinguishable from those of a disruption mutation in which the entire motor domain is not expressed. © 1995 Wiley-Liss, Inc.
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  • 55
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    Cell Motility and the Cytoskeleton 32 (1995) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 56
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    Cell Motility and the Cytoskeleton 32 (1995), S. 233-243 
    ISSN: 0886-1544
    Keywords: caldesmon ; over-expression ; cell cycle ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Caldesmon is an actin, calmodulin, tropomyosin, and myosin binding protein implicated in the regulation of actomyosin interactions. We have invesigated the effect of overexpression of the higher molecular weight smooth muscle isoform of caldesmon on mouse L cell physiology. Mouse L(TK-) cell were transfected stably with plasmids carrying the TK+ gene and a full length human smooth muscle caldesmon cDNA under control of the adenovirus major late promoter. Two clones displaying four and eight times the level of the endogenous mouse high molecular weight caldesmon were isolated. These cells acquire a distinct phenotype characterized by an altered morphology, including an increased number of processes and larger area due to enhanced cell spreading, and a significantly slower growth rate than that of untransfected control cells, or cells transfected with the TK+ gene alone. The majority of the overexpressed caldesmon appears to be active and localized on cytoskeleton structures as determined by detergent lysis. Immuno-fluorescence analysis of the clones revealed that the caldesmon is localized as punctate staining on stress-fibers and in membrane ruffles. The immunofluores-cence images suggest that caldesmon overexpressing cells have more total filaments than control cells. The effects of excess caldesmon on cell mobility are ambiguous: one clone displayed increased motility compared to the control, while the motility of the second clone was decreased relative to the control. © 1995 Wiley-Liss, Inc.
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  • 57
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    Cell Motility and the Cytoskeleton 32 (1995), S. 258-272 
    ISSN: 0886-1544
    Keywords: adhering junctions ; desmosome ; assembly ; phosphorylation ; protein interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have analyzed the kinetics of synthesis, phosphorylation, and stability of the soluble and insoluble plakoglobin (PG) and their interactions with Dsg1 and E-cadherin in Madin-Darby canine kidney (MDCK) epithelial cells in the absence of cell adhesion and after the induction of cell-cell contact. Using a combination of biochemical and morphological approaches, we show that newly synthesized PG enters a soluble:insoluble pool of proteins in a 60:40 ratio regardles of cell-cell contact. Following synthesis, PG is increasingly found in the insoluble pool. Although cell-cell contact does not effect either the size of each pool or the rate or efficiency of the transfer from the soluble into the insoluble pool, it results in a significant increase in the metabolic stability of the newly synthesized insoluble PG. The soluble PG initially forms separate complexes with E-cadherin and Dsg1. PG-Dsg1 complexes become insoluble and localize to the desmosome. PG-E-cadherin complexes remain soluble and are distributed intracellularly. The insoluble PG and E-cadherin detected at the cell periphery remain distinctly separate, as demonstrated previously [Hinck et al., 1994: J. Cell Biol. 125:1327-1340; Nathke et al., 1994: J. Cell Biol. 125:1341-1352]. In addition, we detected a separate pool of PG which is not associated with either Dsg1 or E-cadherin and after the induction of cell-cell contact becomes primarily insoluble and is distributed along the lateral membrane. Phoshorylation analysis showed that there is a significantly greater amount of phosphorylated PG in the soluble pool than in the insoluble pool. In addition the soluble pool is both serine and theronine phosphorylated, whereas the insoluble PG is primarily phosphorylated on serine residues. © 1995 Wiley-Liss, Inc.
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  • 58
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    Cell Motility and the Cytoskeleton 32 (1995), S. 273-288 
    ISSN: 0886-1544
    Keywords: microtubules ; γ-tubulin ; polarized epithelia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubules oriented in the apicobasal axis of columnar epithelial cells arranged with a uniform polarity with minus ends toward the apical surface, suggesting that these cytoskeletal filaments might serve as a substrate for polarized movement of membrane vesicles within the cell. It is not known whether hepatocytes, a cuboidal epithelium in which transcellular transport is a requisite step in normal apical membrane biogenesis, contain microtubules arranged with a similar polarity. In the present study, we explore the question of microtubule polarity and possible mechanisms for nucleation in the epithelial cell lines WIF-B (hepatocyte), Caco-2 (intestine), and Madin-Darby canine kidney (MDCK). Caco-2 microtubules in the apicobasal axis had uniform polarity with minus ends nearest the apical surface. After cold and nocodazole-induced depolymerization, microtubule regrowth initiated in the apical region in all three cell types. The apex of WIF-B and Caco-2 cells contained two pools of γ-tubulin: one associated with centrosomes and the other delocalized under the apical membrane. Non-centrosomal γ-tubulin was present in complexes that sedimented between 10S and 29S; both forms could bind microtubules. The presence of both centrosomal and noncentrosomal γ-tubulin in apical cytoplasm suggests multiple mechanisms by which microtubule nucleation might occur in epithelial cells. © 1995 Wiley-Liss, Inc.
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  • 59
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    Cell Motility and the Cytoskeleton 32 (1995), S. 245-257 
    ISSN: 0886-1544
    Keywords: actin ; cytochalasin ; microfilaments ; microtubules ; mitosis ; mitotic apparatus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: PtK1 cells were treated with 10 μg/ml cytochalasin J (CJ) for 15 min at various stages of mitosis. When applied at nuclear envelope breakdown (NEB) chromosome congression was blocked or substantially slowed, and chromosomes failed to show organization patterns typical of prometaphase. Spindle microtubule (MT) numbers appeared unaffected as judged by the pattern of birefringent retardation. However, ultrastructural analysis showed MTs to be reorganized within the spindle domain with some exhibiting fragmentation and others failing to interact with poorly defined kinetochore laminae. The spindle domain took on a curved, almost banana-like shape, as related to the position of the centrosomes and lack of orientation of chromosomes. Serial section analysis of kinetochore regions showed reduced contour length and maturation of the kinetochore plate with few MTs associated with this structure. Cells similarly treated with 10 μg/ml CJ at NEB for 15 min and then released into conditioned medium for 15 min showed that most chromosomes resumed congression to the metaphase plate. Ultrastructural analysis revelaed a more normal organization of spindle MTs, but kinetochore structure remained affected. CJ treatment of cells in prometaphase slightly affected chromosome congression with most chromosomes aligning at the metaphase plate after 10-15 min of treatment. Ultrastructural analysis showed that astral MTs were disrupted and spindle MTs were fragmented; few MTs coursed from kinetochore to pole. Kinetochore structure was also affected with only small numbers of short MTs seen associated with kinetochores. Application of CJ at anaphase onset had little effect on anaphase A and B, but cytokinesis failed to occur. Anti-tubulin staining of a monolayer of cells treated with 10 μg/ml CJ for 15 min showed that over 60% of mitotic figures exhibited changes in MT organization. Cells showing the greatest effect of treatment had several foci of bundles of MTs, as if the spindle were multipolar. Chromosomes were arranged near the periphery of the spindle which could be a result of abnormalities of kinetochore structure. Improper association of spindle MTs with kinetochores and, thus, changes in kinetochore position could account for these changes in spindle architecture. © 1995 Wiley-Liss, Inc.
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  • 60
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    Cell Motility and the Cytoskeleton 32 (1995), S. 289-298 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; intermediate filaments ; vimentin ; microtubules ; myoepithelial cells ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Salivary gland neoplastic myoepithelial cells in culture form very thin cytoplasmic processes in which the vimentin network is well dispersed. These vimentin filaments can be individually visualized by immunofluorescence. In this study, we have analyzed the role of microtubules in the distension and organization of the vimentin filament network found in these cells. We find that vimentin filaments colocalize along microtubules; however, a significant number of filaments can also be found in microtubule-free domains. Additionally, vimentin filaments are absent from large domains of microtubule inhibitor nocodazole did not cause any retraction of the distended vimentin network. This observation suggests that the structural integrity of microtubules is not important for the stability of the vimentin network. Combining procedures for transient disruption of vimentin filaments and microtubules we observed that, in the absence of microtubules, the vimentin network could reassemble in the perinuclear region but was unable to extend toward the cell periphery. The dispersion of vimentin filaments to the peripheral regions of the cytoplasm could only be observed upon microtubule reassembly. This indicates that microtubules are not required for the stability of the vimentin network, but the dispersion of vimentin filaments to the peripheral cytoplasm depends on active interactions with microtubules. © 1995 Wiley-Liss, Inc.
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  • 61
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    Cell Motility and the Cytoskeleton 32 (1995), S. 299-304 
    ISSN: 0886-1544
    Keywords: 3T3 cells ; CV1 cells ; cell motility ; infrared ; photobiology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 3T3 mouse fibroblasts responded differently to specific near-infered signals than epithelial CV1 cell. Furthermore, signals with the same wavelength and energy changed the percentages of attracted and repelled 3T3 cells if their intensity modulation was altered. I found this result in a 22 month long study which established a spectrum of motile responses of 781 individual 3T3 cells and 148 CV1 cells to the near-infrared emissions of microscopic, pulsating light sources using the infrared spot-irradiation phase-contrast (IRSIP) microscopic [Albrecht-Buehler, 1991: J. Cell Biol. 114:493-502]. Thus the response of cultured, mammalian cells to near-infrared light signals is not merely a matter of total energy absorption by cirtain cytoplasmic componets. Since it seems to depend on the cell type and the temporal pattern in which the light energy is emitted, it appears to imply the existence of a new kind of cellular information. © 1995 Wiley-Liss, Inc.
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  • 62
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    Cell Motility and the Cytoskeleton 32 (1995), S. 305-317 
    ISSN: 0886-1544
    Keywords: organelle transport ; cytoskeleton ; amoeba ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using video-enhanced differential interference microscopy and digital image processing, we have observed organelle motility in Acanthamoeba castellanii. In amoebae taken from cultures in rapid growth phase, mitochondria and small particles moved over distances of several microns and at an average velocity of ∼2 μ/s. Mitochondrial motility was verified by intensified fluorescence microscopy of cells that were labeled in vivo with the DNA-binding dye DAPI or the mitochondria-specific dye Mito Tracker. We further studied the role of microtubules (MTs) in the translocation of cell organelles. Double-labelling of fixed cells bules with mitochondrial markers (anti-F1β antibody, Mito Tracker) and cytoskeletal markers (anti-tubulin antibody, rhodamine-phalloidin) demonstrate that the mitochondria colocalize with MTs in the subcortical cell area and are excluded from the F-actin-rich cell cortex. Colchicine treatment resluted in an almost complete depolymerization of MTs and an inhibition of organelle motility. Moreover, we have directly visualized MTs in vivo in flattened amoebae. Mitochondria and small particles moved along the MTs in a bidirectional mode at an average velocity of ∼1 μm/s. We conclude that the observed movement of mitochondria and small particles in Acanthamoeba castellanii mainly occurs via microtubules and associated motor proteins. © 1995 Wiley-Liss, Inc.
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  • 63
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    Cell Motility and the Cytoskeleton 30 (1995), S. 26-37 
    ISSN: 0886-1544
    Keywords: myosin ; myosin-I ; unconventional myosin ; brush border ; epithelia ; membrane ; phospholipid ; fluorescence microscopy ; actin ; calmodulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Brush border myosin-I (BBMI) is associated with the membrane of intestinal epithelial cells where it probably plays a structural role. BBMI also has been identified on Golgi-derived vesicles in intestinal epithelial cells where it may translocate vesicles into the brush border. However, the mechanochemical activity of BBMI bound to a phospholipid membrane has not been described. This study reports that phospholipid membrane-associated BBMI displays ATPase activity when bound to phospholipids, but does not move actin filaments when associated with a phospholipid bilayer. BBMI does not bind significantly to brush border membrane lipids, which contain about 16% phosphatidylserine (PS), in either a pelleting or planar membrane assay. Similarly, planar membranes containing 20% PS do not bind a significant amount of BBMI. Increasing the concentration of PS to 40% does result in the binding of BBMI to both vesicles and planar membranes. This binding is enhanced with increased Ca2+ concentrations. BBMI retains its ATPase activity when bound to phospholipid vesicles containing 40% PS. However, BBMI attached to a phospholipid bilayer surface does not move actin filaments, even though the amount of BBMI bound to the lipid surface, as reflected by the number of actin filaments associated with bilayer-bound BBMI, is sufficient to observe motility in control experiments. When membrane fluidity is reduced by adding cholesterol to the membrane lipids containing 40% PS, BBMI still binds to the membrane, but again no actin filament motility is observed. The lack of binding by BBMI to brush border membrane lipids and the absence of membrane-associated BBMI mechanical activity suggest that factors in addition to membrane lipids are necessary for membrane-associated myosin-I motility. © 1995 Wiley-Liss, Inc.
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  • 64
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    Cell Motility and the Cytoskeleton 30 (1995), S. 171-182 
    ISSN: 0886-1544
    Keywords: tubulin ; post-translational modification ; glutamylation ; tyrosination ; dipeptide antibodies ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two monoclonal antibodies, GLU-1 and A1.6, raised against γ-L-glutamyl-L-glutamic acid dipeptide (Glu-Glu) and Ca2+ -dependent ATPase from Paramecium, respectively, recognized the dipeptide Glu-Glu sequence. Whereas the antibodies immunofluorescently stained very few, if any, cytoskeletal fibers in cultured mammalian cells, almost all interphase as well as mitotic spindle microtubules became visible after treatment of cells with carboxypeptidase A. Immunoblot analysis demonstrated intense cross-reaction of the antibodies to the α-tubulin subunit. α-Tubulin isotypes produced as fusion proteins in bacteria were labeled by both the antibodies only when the proteins did not contain a tyrosine residue at the C terminus, indicating that GLU-1 and A1.6 specifically recognize the detyrosinated from of α-tubulin. When microtubule protein purified from brain was probed, not only α-but also, to a lesser extent, β-tubulin were revealed by the dipeptide antibodies. A synthetic tripeptide YED containing one glutamyl group linked to the second residue of the peptide via the γ position was also recognized by the antibodies. Since this peptide sequence corresponds to the amino acid sequence of polyglutamyated class IIIβ isotype at amino acid position 437 to 439, it is suggested that GLU-1 and A1.6 are able to recognize the glutamylated form of β-tubulin. These results indicate that the C-terminal Glu-Glu sequence displays strong antigenicity, and the antibodies recognize the sequence present in the C terminus of the detyrosinated form of α-tubulin and the glutamyl side chain of β-tubulin. Particularly strong immunoreaction was detected with ciliary and flagellar microtubules; thus, stable axonemal microtubules appear to be rich in post-translationally modified tubulin subunits. © 1995 Wiley-Liss, Inc.
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  • 65
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    Keywords: uterus ; leiomyomas ; cultured smooth muscle cells ; α-smooth muscle actin ; desmin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We had previously found no myosin heavy chain (MHC) changes in expression during pregnancy in human myometrium. In the present work, we compared the MHC pattern of expression in normal human myometrium, pregnant and non-pregnant, to that in benign tumors of the uterine musculature and in cultured myometrial cells. We used a high-resolution gel electrophoretic system and monoclonal antibodies directed against smooth muscle and nonmuscle MHCs. Smooth muscle MHCs (SM1, 204 kDa, and SM2, 200 kDa, MHCs) and a nonmuscle MHC of 196 kDa (NM MHC) were detected in pregnant and nonpregnant human myometrium. Pregnant myometrium was found to differ from nonpregnant myometrium by its slightly lower content in NM MHC, whereas the ration of SM1/SM2 was equivalent. In leiomyomas and in cultured cells grown from human myometrium explants, SM1, SM2, and NM MHCs were also expressed. In addition, a nonmuscle MHC of 198/200 kDa (SMemb MHC), which was present in a fetal human uterus but not in adult normal tissue, was observed in leiomyomas and in cultured cells. Expression of SM1 and SM2 MHCs was variable in the different leiomyomas studied. In cultured cells, SM1 and SM2 MHC content was low, but it was enhanced by suppression of serum after cell confluency. Present results confirm that pregnancy-associated smooth muscle cell hypertrophy is not accompanied by major changes in MHCs. In contrast, cell culturing and cell hyperplasia leading to leiomyoma formation induce substantial modifications in MHCs, including the occurrence of a second type of nonmuscle MHC. © 1995 Wiley-Liss, Inc.
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    Cell Motility and the Cytoskeleton 30 (1995), S. 221-228 
    ISSN: 0886-1544
    Keywords: Key words: microtubules, flexural rigidity, optical trapping, microtubule-associated proteins, taxol ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As major determinants of cell shape and polarity, microtubules are required to have suitable rigidity. However, our knowledge of the mechanical properties of microtubules is far from satisfactory. We report here a new method of measuring the flexural rigidity of a single microtubule by direct buckling using the optical trapping technique. Microtubule buckling was induced by applying a small longitudinal compressing force through an optically trapped microsphere that was firmly attached to the microtubule. Three ways of estimating the flexural rigidity of a continuous slender rod, one from the observed critical load of buckling and two from deflected lengths and angles of bending, yielded values which agreed well when applied to the analysis of buckling microtubules. Unexpectedly, we found that the rigidity was not constant as expected but was dependent on microtubule length. This length dependency explains the discrepancies among reported values of microtubule flexural rigidity measured by different methods. Comparing microtubules of identical lengths, microtubules assembled with brain-derived associated proteins (4 × 10-23 Nm2 at around 10 m̈m in length) were four times more rigid than those assembled from purified tubulin and stabilized with taxol (1 × 10-23 Nm2). © 1995 Wiley-Liss, Inc.
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  • 67
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    Cell Motility and the Cytoskeleton 30 (1995), S. 73-84 
    ISSN: 0886-1544
    Keywords: myosin I ; yeast ; SH3 ; proline-rich ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The family of myosin motors is comprised of numerous classes distributed among a diverse set of organisms and cell types. We have identified an unconventional myosin gene (MYO3) in the yeast Saccharomyces cerevisiae and show that it is member of a subclass of unconventional myosin proteins originally found only in the amoeboid organisms Dictyostelium and Acanthamoeba. Identification of this protein in these genetically and morphologically divergent organisms suggests that it will be ubiquitous in eukaryotes and that it has a role in the basic functions of the eukaryotic cell. We have constructed a strain of yeast missing 99% of the MYO3 coding sequence. This mutation has no observable phenotypic effect, placing MYO3 into a growing class of yeast genes which are dispensable under laboratory conditions, perhaps due to genetic redundancy. Alignment of MYO3 with other unconventional myosins shows that it shares with a subset of them a previously unrecognized region of homology in the tail; this region falls within a domain identified as important for mediating nonspecific electrostatic interactions with membranes. The existence of this region suggests that it may be involved in mediating specific protein-protein interactions, possibly helping to localize this myosin to specific membranes or membrane regions. In addition, we show that “classic” myosin I proteins share a region of hyper-proline-richness 10 amino acids before the SH3 domain. Proline-rich regions have recently been implicated as SH3 binding sites, which suggests that this region might be involved with regulating or in other ways interacting with SH3 domains. © 1995 Wiley-Liss, Inc.
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  • 68
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    Cell Motility and the Cytoskeleton 31 (1995), S. 177-195 
    ISSN: 0886-1544
    Keywords: focal adhesion ; stress fiber ; vinculin ; talin ; integrin ; focal adhesion kinase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human fibroblasts stained with fluorescently labeled phalloidin revealed many stress fibers within the apical cytoplasm in addition to those located along the basal plasma membrane and associated with focal adhesions. The staining patterns of these apical stress fibers with fluorescent phalloidin, anti-α-actinin, and anti-myosin were identical to those of the basal stress fibers, suggesting the same macromolecular organization for both types f stress fibers. There were two types of apical stress fibers that clearly interacted with the apical plasma membrane, those extending between the basal and the apical plasma membrane and those having both ends on the basal membrane forming arches whose top interacted with the apical plasma membrane. By electron microscopy, we observed that apical stress fibers were associated with the apical plasma membrane via electron-dense plaques reminiscent of the focal adhesion. Since several proteins have been specifically localized to the focal adhesion site, we examined whether they were also present at the apical stress fiber-membrane association site by using immunocy-tochemical methods and image reconstruction techniques. We found that vinculin, talin, paxillin, a fibronectin receptor protein, several integrin subunits including β1, fibronectin, and proteins with phosphorylated tyrosine were also components of the apical plaque. These observations indicate that apical stress fibers are attached to the plasma membrane by using principally the same molecular assembly as the focal adhesion associated with the basal stress fiber. We suggest that the complex molecular organization of the focal adhesion is not demanded by cell adhesion, but rather it is needed for anchoring stress fibers to the plasma membrane. Apical plaques did not stain with the anti-integrin αv subunit or anti-focal adhesion associated kinase (FAK), although these antibodies stained focal adhesions. These results suggest that the apical stress fiber-membrane contact has some important functions different from those of the focal adhesion.
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  • 69
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; heparan sulfate proteoglycans ; heparin-binding proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell surface proteoglycans participate in molecular events that regulate cell adhesion, migration, and proliferation. To investigate the organization of these molecules at the cell surface, the distribution of two well-known proteoglycan ligands has been studied. These ligands, lipoprotein lipase and basic fibroblast growth factor, showed a characteristic binding pattern consisting of highly organized parallel arrays that crossed the upper surface of human skin fibroblasts. The proteoglycan nature of the binding sites was evident from their susceptibility to heparinases, and from ligand displacement by heparin. Parallel localization of the ligands and actin, and treatment of the cells with cytochalasin, showed that the binding proteoglycans are organized by the actin cytoskeleton. The ligands induced a different behaviour of the binding sites on incubation of the cells at 37°C. Lipoprotein lipase produced a movement of the binding proteoglycans along the actin filaments towards the cell center. In contrast, after binding of basic fibroblast growth factor the binding proteoglycans remained spread over the cell surface and actin depolymerization was induced. Since an increasing number of ligands appear to depend on proteoglycans for their interactions with their high affinity receptors, distribution and movement of proteoglycans at the cell surface that is organized by the actin cytoskeleton could direct and enhance the encounters between the ligands and their specific receptors. © 1995 Wiley-Liss, Inc.
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  • 70
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    Cell Motility and the Cytoskeleton 30 (1995), S. 122-135 
    ISSN: 0886-1544
    Keywords: egg activation ; erbstatin ; phosphatase ; post-translational modification ; phosphotyrosine ; sperm ; sperm aster ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Protein tyrosine phosphorylation plays an important role in cell growth, mitosis, and tumorigenesis. It has also been implicated in meiotic maturation and fertilization. We have used anti-phosphotyrosine immunofluorescence and immunoblotting to identify sperm and egg proteins which are phosphorylated on tyrosine residues prior to and during sea urchin fertilization. On immunoblots of sperm proteins, the monoclonal anti-phosphotyrosine antibody detected three major proteins with molecular weights of 44, 82, and 100 kD, and six minor bands at 46, 48, 70, 76, 95, and 150 kD. These phosphotyrosyl proteins were localized to the sperm acrosomal and centriolar fossae. In contrast, staining was found globally in unfertilized eggs, and the antibody recognized two major egg phosphotyrosyl proteins of molecular weights 42 and 50 kD, and five minor bands at 40, 90, 116, 130, and 150 kD. While immunofluorescent staining remained throughout the fertilized egg cytoplasm, there were dynamic changes in the staining intensity of single bands. The 90 kD immunoreactive band increased in intensity, and the 40 and 42 kD bands disappeared by 15 min after fertilization. Loss of the 40 and 42 kD bands was due to dephosphorylation by okadaic acid-sensitive phosphatase(s). The 50 kD immunoreactive protein was unchanged up to the 8-cell stage and was still present in blastulae, indicating its importance throughout fertilization and early development. Alterations in the pattern of phosphotyrosine-containing proteins during fertilization did not depend on nascent proteins and could not be completely mimicked by increasing intracellular calcium, pH, and protein kinase C activity alone. Since changes in the fertilization pattern of phosphotyrosyl proteins occurred during formation of the sperm aster and mitotic spindle, we analyzed the role of protein tyrosine kinase activity in these processes using the tyrosine kinase specific inhibitor, erbstatin. Both the sperm aster and mitotic spindle were disrupted, indicating an involvement of tyrosine phosphorylation in these processes during interphase and mitosis. We conclude that the changes in phosphotyrosyl proteins play an important role in fertilization and early development of sea urchin eggs. Control of microtubule assembly into the sperm aster and mitotic spindle of the first cell cycle are examples of such roles. © 1995 Wiley-Liss, Inc.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 215-224 
    ISSN: 0886-1544
    Keywords: RBL-2H3 cells ; vinculin ; mast cells ; talin ; cytoskeleton ; permeabilized ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adherence of cells to the extracellular matrix via focal adhesions is known to modulate many cellular functions. However, the role of focal adhesions in the regulation of secretion is unclear. To examine this we have used the RBL-2H3 rat mast cell line, in which we and others have observed cytoskeletal rearrangements and increased cell spreading during secretion. All activators of secretion examined, whether acting specifically through or bypassing the IgE-receptor, induced the assembly of focal adhesions, as defined by the localization of vinculin and talin. The extent of focal adhesion formation correlated with the extent of secretion and the time course of secretion also correlated with that of the assembly of focal adhesions. To examine the mechanism by which focal adhesion formation occurred, the protein kinase C inhibitor bisindolylmaleimide was used. Bisin-dolylmaleimide caused complete inhibition of both secretion and focal adhesion formation induced by antigen or the calcium ionophore A23187. Although PMA did not induce secretion, it induced focal adhesion assembly which was inhibited by bisindolylmaleimide. The inhibitor had no effect on secretion or focal adhesion formation induced by the ATP analogue, ATPγS in permeabilized cells, indicating ATPγS acts after the activation of protein kinase C in the secretory pathway. These data provide novel evidence that the formation of focal adhesions may have a role in the process of secretion from mast cells.
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  • 72
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    Cell Motility and the Cytoskeleton 31 (1995), S. 22-33 
    ISSN: 0886-1544
    Keywords: amphibian ; axonemes ; cilia ; dynein ; lung ; respiratory ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dyneins are multimeric ATPases that comprise the inner and outer arms of cilia and flagella. It previously has been shown that salt extraction of newt lung axonemes selectively removes 〉95% of the outer arm dynein (OAD), and that the beat frequency of OAD-depleted axonemes cannot be activated as compared to controls [Hard et al., 1992: Cell Motil. Cytoskeleton 21:199-209]. Therefore, expression of the activated state appears to require the presence of outer dynein arms. The presen study was undertaken to ascertain basic information on the structure and molecular composition of newt OAD. Populations of demembranated axonemes were extracted with 0.375 M salt. Each lung released ∼ 1.4 × 107 axonemes during isolation, yielding ∼ 120 ng of salt extractable OAD. Electron microscopy of negatively stained samples revealed that newt OAD consisted of two globular heads joined together by a Y-shaped stem, similar to sea urchin and trout sperm OAD. Each head appeared to be roughly spherical in shape, measuring ∼ 17 nm in diameter. Electrophoretic analysis of whole axonemes revealed more than six dynein heavy chains when resolved in silver stained 0-8 M urea, 3-5% acrylamide gradients. Extracted OAD, either crude in high salt or purified by alloaffinity, was composed of two heavy chains. UV-induced (366 nm) photolytic cleavage at the V1 site, performed in the presence of Mg2+, vanadate, and ATP, produced four new polypeptides (Mr 234, 232, 197, and 189 kD). Photolysis was supported by Mg2+ and Ca2+, but did not occur in the presence of Mn2+. The apparent Mr of the dynein heavy chains was determined to lie between 430-420 kD. Eight discrete polypeptides (putative intermediate chains, IC1-IC8, Mr 175-56 kD) copurified with the α- and β-heavy chains by microtubule-alloaffinity.Based on its extraction characteristics, polypeptide composition in purified and crude samples, and structure, we conclude that this two-headed particle represents the entire newt respiratory outer arm dynein.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 34-44 
    ISSN: 0886-1544
    Keywords: microtubule ; MTOC ; mitosis ; MPM-2 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In diverse cell types, monoclonal antibody MPM-2 recognizes a class of phosphorylated proteins related to microtubule organizing centers and abundant during mitosis. We have used this antibody in an attempt to identify the spatial and temporal localization of putative microtubule organizing centers in endosperm cells of the higher plant Haemanthus. Our results show that MPM-2 recognized epitope is present in interphase cells and enriched in mitotic cells. In interphase the antibody usually stains cytoplasmic granules. During the interphase-prophase transition immunoreactive material appears in the nucleus, at the nuclear envelope, and in association with microtubules. Concomitantly, we observed an increase of immunoreactivity of the cytoplasm. During mitosis the phosphorproteins recognized by MPM-2 are detected in the cytoplasm, in association with microtubules of the spindle, the phragmoplast, and in the newly-formed cell plate. After completion of mitosis, only the cell plate and cytoplasmic granules are MPM-2 positive. Extraction of the cells with Triton X-100 prior to fixation removes staining of the cytoplasm by MPM-2. The detergent resistant immunoreactive material remains associated with surrounding the nucleus microtubules of the prophase spindle, the core of kinetochore fibers, and the phragmoplast. In the phragmoplast, however, segments of microtubules which are distal to the cell plate are depleted of MPM-2.These data demonstrate that microtubule arrays of endosperm cells are phosphorylated during mitosis. Thus, similar to animal cells, interphase and mitotic microtubules of higher plants have different properties. Additionally, the localization of detergent resistant MPM-2 antigen points to the difference in microtubule nucleation/organization between higher plant and animal cells.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 45-58 
    ISSN: 0886-1544
    Keywords: colcemid ; kinesin ; actin ; topographic guidance ; micromachined substrata ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fibroblats cultured on grooved substrata align themselves and migrate in the direction of the grooves, a phenomenon called contact guidance. Microtubules have been deemed important for cell polarization, directed locomotion, and contact guidance. Because microtubules were the first cytoskeletal element to align with the grooves when fibroblasts spread on grooved substrata, we investigated the consequences of eliminating the influence of microtubules by seeding fibro-blasts onto smooth and grooved micromachined substrata in the presence of colcemid. Fibroblasts were examined by time-lapse cinematography and epifluorescence or confocal microscopy to determine cell shape and orientation and the distribution of cytoskeletal or associated elements including actin filaments, vinculin, intermediate filaments, microtubules, and kinesin.As expected, cells spreading on smooth surfaces in the presence of colcemid did not polarize or locomote. Surprisingly however, by 24 hours, cells spread on grooves in the presence of colcemid were morphologically indistinguishable from controls spread on grooves. Both groups were aligned and polarized with the direction of the grooves and demonstrated directional locomotion along the grooves. In the absence of microtubules, kinesin localized to some of the aligned stress fibers and to leading edges of cells spreading on grooves. The grooved substratum compensated for the microtubule deficiency by organizing and maintaining an aligned actin filament framework. Thus, microtubules are not required to establish or maintain stable, polarized cell shapes or directed locomotion, provided an alternate oriented cytoskeletal component is available.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 82-82 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 76
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    Cell Motility and the Cytoskeleton 31 (1995), S. 59-65 
    ISSN: 0886-1544
    Keywords: flagella ; cane-shaped bend ; principal bend ; calcium ; membrane depolarization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To investigate the mechanism of the flagellar quiescence in sperm, we examined the effect of electric stimulation of individual spermatozoa of the sea urchin, Hemicentrotus pulcherrimus. Stimulation with a suction electrode attached to the sperm head elicited a flagellar quiescence response, in which the sperm showed a typical cane-shaped bend in the proximal region of the flagellum when the electrode was used as anode. Cathodic stimulation also induced quiescence, but was much less effective than anodic stimulation. During the quiescence response, which lasted for 1-3 s, no new bend was initiated, and subsequently the flagellum resumed normal beating. The quiescence response required the presence of Ca2+ (〉2 mM) in sea water, and was inhibited by Co2+ and La3+. At low Ca2+ concentrations (2-5 mM), the angle of the cane-shaped bend was smaller than that at 10 mM Ca2+; thus the angle of the cane-shaped bend, characteristic of the quiescence response is dependent on Ca2+ concentration. These results suggest membrane, followed by an influx of Ca2+ into the flagellum through Ca2+ channels. The increase in Ca2+ concentration within the flagellum affects the amount of sliding and thus produces a cane-shaped proximal bend of various angles, white inhibiting both the propagation of the proximal bend (principal bend) and the formation of a new reverse bend.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 66-81 
    ISSN: 0886-1544
    Keywords: microtubule motor proteins ; immunolocalization ; RT-PCR ; Northern/Southern blots ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To examine the possible role of kinesin in pigment granule migration in the retinal pigment epithelium (RPE) of teleosts, we investigated the expression and distribution of kinesin heavy chain (KHC) in RPE. Blots of fish RPE lysates probed with two well-characterized antibodies to KHC (H2 and HD) displayed a prominent band at 120 kD. A third KHC antibody (SUK4) recognized a band at 118 suggesting the presence of two KHC isoforms in teleost RPE. Reverse transcriptase-polymerase chain reaction (RT-PCR) of mRNA from RPE using primers homologous to conserved regions of the KHC motor domain resulted in the homologous to conserved regions of the KHC motor domain resulted in the identification of two putative KHC genes (FKIF1 and FKIF5) based on partial amino acid sequences. Previous studies had demonstrated a requirement for microtubules in pigment granule aggregation in RPE. In addition, the reported microtubule polarity orientation in RPE apical projections is consistent with a role for kinesin in pigment granule aggregation. Immunofluorescent localization of KHC in isolated RPE cells using H2 revealed a mottled distribution over the entire cell body, with no detectable selective association with pigment granules, even in cells fixed while aggregating pigment granules. Microinjected KHC antibodies had no effect on pigment granule aggregation or dispersion, although each of the three antibodies has been shown to block kinesin function in other systems. Thus we found no evidence for KHC function in RPE pigment granule aggregation. However, the two KHC isoforms may participate in other microtubule-dependent processes in RPE.
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    Cell Motility and the Cytoskeleton 31 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 31 (1995), S. 87-92 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Cell Motility and the Cytoskeleton 31 (1995), S. 113-129 
    ISSN: 0886-1544
    Keywords: Arabidopsis ; centrosome ; CIPC ; colchicine ; cytokinesis ; γ-tubulin ; microtubule ; mitosis ; phragmoplast ; taxol ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: γ-Tubulin-specific antibodies stain the microtubule (Mt) arrays of Arabidopsis suspension cells in a punctate or patchy manner. During division, staining of kinetochore fibers and the phragmoplast is extensive, except in the vicinity of the plus ends at the metaphase plate and cell plate. γ-Tubulin localization responds to low levels of colchicine, with staining receding farther toward the minus (pole) ends of kinetochore fibers. At higher drug concentrations, γ-tubulin also associates with abnormal Mt foci as well as with the surface of the daughter nuclei facing the phragmoplast. During UV-induced recovery from colchicine, γ-tubulin increases along the presumptive minus ends of mitotic Mts as well as the phragmoplast near the daughter nuclei. With CIPC, immunostaining is concentrated around the centers of focal Mt arrays in multipolar spindles. In the presence of taxol, Mts are more prominent but the mitotic apparatus and phragmoplast are abnormal. As with CIPC, γ-tubulin is concentrated at focal arrays. Increased punctate staining is also present in interphase arrays, with fluorescent dots often located at the ends of Mts. These results support a preferential association between γ-tubulin and Mt minus ends, but are also consistent with more general binding along the walls of Mts. Thus, minus ends (and Mt nucleation sites) may be present throughout plant Mt arrays, but γ-tubulin may also serve another function, such as in structural stabilization.
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  • 81
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    Keywords: cleavage furrow ; cytokinesis ; contractile ring ; microfilament ; stress fibers ; microfilament networks ; intestinal epithelium ; spleen cells ; dorsal root ganglia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two principal isoforms of cytoplasmic myosin II, A and B (CMIIA and CMIIB), are present in different proportions in different tissues. Isoform-specific monoclonal and polyclonal antibodies to avian CMIIA and CMIIB reveal the cellular distributions of these isoforms in interphase and dividing embryonic avian cardiac, intestinal epithellal, spleen, and dorsal root ganglia cells in primary cell culture. Embryonic cardiomyocytes react with antibodies to CMIIB but not to CMIIA, localize CMIIB in stress-fiber-like -structures during interphase, and markedly concentrate CMIIB in networks in the cleavage furrow during cytokinesis. In contrast, cardiac fibroblasts localize both CMIIA and CMIIB in stress fibers and networks during interphase, and demonstrate slight and independently regulated concentration of CMIIA and CMIIB in networks in their cleavage furrows. V-myc-immortalized cardiomyocytes, an established cell line, have regained the ability to express CMIIA, as well as CMIIB, and localize both CMIIA and CMIIB in stress fibers and networks in interphase cells and in cleavage furrows in dividing cells. Conversely, some intestinal epithelial, spleen, and dorsal root ganglia interphase cells express only CMIIA, organized primarily in networks. Of these, intestinal epithelial cells express both CMIIA and CMIIB when they divide, whereas some dividing cells from both spleen and dorsal root ganglia express only CMIIA and concentrate it in their cleavage furrows. These results suggest that within a given tissue, different cell types express different isoforms of CMII, and that cells expressing either CMIIA or CMIIB alone, or simultaneously, can form a cleavage furrow and divide.
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    Cell Motility and the Cytoskeleton 32 (1995), S. 226-232 
    ISSN: 0886-1544
    Keywords: Z-line interconnections ; honey-bee flight muscle ; transverse cytoskeletal network ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Located at the level of the Z-line, the transverse cytoskeletal network of insectflight muscle interconnects adjacent myofibrils with one another, and interconnects peripheral myofibrils with the cell membrane. This network has been presumed to keep myofibrils in register, or to distribute tension laterally among myofibrils. In this study, we used scanning-electron microscopy to reveal details of the three-dimensional arrangement of this network. The network is seen to interconnect longitudinal elements of the cytoskeletal network which surround each myofibril. The arrangement is not unlike that seen in vertebrate skeletal muscle. Interestingly, the transverse network makes contact with cell components such as dense bodies and mitochondria. Such contacts imply potential roles over and above those noted above. The network may be involved not only in mechanical function, but possibly also in intracellular communication. © 1995 Wiley-Liss, Inc.
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    Cell Motility and the Cytoskeleton 32 (1995), S. 162-162 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 32 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 32 (1995), S. 163-172 
    ISSN: 0886-1544
    Keywords: actin ; C-terminus ; α-actinin ; myosin ; myofibrils ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A series of deletions was made from the C-terminal end of actin by inserting termination codons into a full length cDNA of human α-skeletal muscle actin. These included deletions of 2, 3, 10, 20, 30, and 40 amino acids. The cDNA clones were transcribed and the resulting mRNA were translated in vitro using 35S-labeled methionine. The 35S-labeled actin and actin mutants were then tested for the ability to coassemble with carrier actin, bind DNAse I, bind myosin S-1, bind a 27 kDa proteolytic fragment of α-actinin, and incorporate into myofibrils in vitro. Removal of the C-terminal two or three amino acids did not grossly alter the properties of actin tested. Deletion of an additional 7 amino acids (10 amino acids total) significantly decreased coassembly, binding to DNAse I, and incorporation into myofibrils, but did not dramatically reduce binding to myosin S-1 or the 27 kDa fragment of α-actinin. Deletion of 20 or more amino acids virtually abolished all normal actin function tested. By examining the structure of actin, we propose that the effect of removing residues 356-365 is due to the important role Trp356 plays in maintaining hydrophobic bonds between three non-contiguous segments of actin. We also suggest that removal of residues 366-372 adversely affected the structure or orientation of the DNAse I binding loop and that this change can account for defects in actin binding to DNAse I, coassembly with wild type actin, and incorporation into myofibrils. © 1995 Wiley-Liss. Inc.
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    Cell Motility and the Cytoskeleton 32 (1995), S. 55-64 
    ISSN: 0886-1544
    Keywords: retina ; photoreceptor cells ; cytoskeleton ; centrin ; Ca2+-binding proteins ; mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Photoreceptor cells of vertebrate retinae are highly specialized ciliary cells. Their non-motile ciliated structure is restricted to the so-called connecting cilium at the joint between the light sensitive outer segment and the metabolically active inner segment. Extensive bidirectional intracellular transport between both segments is forced to occur through this tight connecting cilium. In the present study it is shown that the Ca2+-binding, phospho-protein centrin is present in mammalian retinae. Western blot and immunoprecipitation experiments reveal that anti-centrin antibodies react with purified photoreceptor cell fractions of retinae in bands at a molecular weight of 20 kDa, the molecular weight of centrins found in other cells. Indirect immunofluorescence analysis of cryosections through retinae of different mammalian species show that centrin is present only in centrosomes and basal bodies but also more extensively at the linkage between the inner and the outer segment of the photoreceptor cells. Immunocytological studies on isolated rod cells and immunoelectron microscopy clearly demonstrate a unique presence of centrin in the connecting cilium of photoreceptor cells. High molecular identity between centrins in lower eukaryotes and mammals indicates that centrin may play a role in cellular motility and/or in microtubule severing in the mammalian retina. © 1995 Wiley-Liss, Inc.
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    Cell Motility and the Cytoskeleton 30 (1995), S. 8-16 
    ISSN: 0886-1544
    Keywords: microtubule sliding ; dynein ; sperm motility ; calcium ; vanadate ; Triton X-100 ; sperm models ; micromanipulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bull sperm extracted with 0.1% Triton X-100 can be reactivated to full motility with 0.33 mM Mg-ATP (sperm models). When motile sperm models are treated with 0.66 mM NiSO4, spontaneous motility is lost. During the transition to motility arrest, the beat becomes progressively more asymmetric, finally arresting at one extreme of the beat cycle. After spontaneous motility has been lost, the flagellum retains the ability to respond to mechanical stimulation. If a microprobe is used to bend the flagellum in the direction opposite to its own prevailing curvature and released, the recoil is rapid and overshoots the equilibrium position. When the same flagellum is manipulated in the opposite direction (into a tighter bend of the existing curve), the recoil is slower and does not exceed the initial bend. If a microprobe is used to carefully bend the whole flagellum into a curve, the flagellum will resume continuous beating, but only if the imposed bend is in the direction opposite the natural curvature. The reinstated beating activity (mechanical reactivation) is sustained as long as the flagellum is held by the microprobe. The rate of change of the shear angle in these mechanically reactivated, Ni2+ -inhibited sperm suggests an impaired rate of sliding on one side of the axoneme compared to similarly restrained control sperm. It appears that Ni2+ has a selective inhibitory effect on the dynein arms that bend the flagellum in one direction. Furthermore, the remaining functional arms activate only when the flagellum is bent in the direction opposing their own action. © 1995 Wiley-Liss, Inc.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 130-139 
    ISSN: 0886-1544
    Keywords: dynein ; flagella ; Chlamydomonas mutants ; viscosity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The propulsive force generated by Chlamydomonas mutants deficient in flagellar dynein was estimated from their swimming velocities in viscous media. The force produced by wild-type cell increased by 30-40% when viscosity was raised from 0.9 to 2 cP but decreased as viscosity was further raised above 6 cP. The biphasic dependence of force generation on viscosity was also observed in the mutant idal, which lacks the II component of the inner-arm dynein. The mutant ida4, which lacks the inner-arm 12 component, was extremely susceptible to viscosity and stopped swimming at 6 cP, at which other mutants could swim. In contrast, odal, which lacks the entire dynein outer arm, produced a fairly constant force of about one-third of the wild-type value, over a viscosity range of 0.9-11 cP. In demembranated and reactivated cell models of the wild type, the propulsive force decreased monotonically as viscosity increased. Thus the increase in force generation at about 2 cP observed in live cells may be caused by some unknown mechanism that is lost in cell models. The cell models of odal, in contrast, did not show a marked change in force generation with the change in viscosity. These results indicate that the force generation by the outer-arm dynein greatly depends on viscosity or the velocity of movement, whereas the complete set of inner-arm dynein present in the odal axoneme produces a fairly constant force at different viscosities. These different properties of inner and outer dynein arms should be important in the mechanism that produces flagellar beating.
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    Cell Motility and the Cytoskeleton 31 (1995), S. 140-146 
    ISSN: 0886-1544
    Keywords: cAMP ; ATP ; hypoxia ; motility initiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bovine sperm that were subjected to extended anoxia (2.5 h) in the absence of glycolytic substrates then diluted into oxygenated medium were immotile but metabolically active, producing ATP from lactate via oxidative phosphorylation. In response to anoxia sperm ATP titers dropped from 15-20 μmoles/108 cells to 1-2 μmoles/108 cells in the first 5 min then remained extremely low until reoxygenation. Cyclic AMP titers declined slowly over the anoxic period, but did not show the same scale of depression as ATP. After dilution and re-oxygenation ATP recovered to pre-anoxia levels within 1 min, and cAMP rose to about the pre-anoxia levels. However, motility, which varied quantitatively and qualitatively between ejaculates prior to anoxic treatment, was substantially depressed after extended anoxia in all cases; progressive motility was almost non-existent in post-anoxic sperm. Addition of isobutylmethylxanthine or Cibacron Blue F3GA, both putative phosphodiesterase inhibitors, stimulated a transient peak of cAMP, which was accompanied by motility stimulation. These techniques provide a protocol to manipulate and dissect the biochemical pathways of motility initiation in mammalian sperm.
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    Cell Motility and the Cytoskeleton 31 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 30 (1995), S. 301-309 
    ISSN: 0886-1544
    Keywords: MAP5 ; high-molecular weight MAPs ; tubulin ; actin ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A simple procedure for the purification of MAP1B from bovine brain is described. The procedure requires two ion-exchange chromatographic steps and results in 〉95% pure MAP1B with a typical recovery of about 25-30 mg/kg of brain tissue. SDS-PAGE analysis of the purified protein shows that it is composed of a high molecular mass (330kDa) heavy chain and two low molecular mass (32kDa and 18kDa) associated light chains. The estimated stoichiometry of heavy chain:light chain is 1:2 and 1:0.2 mole/mole protein for the 32kDa and 18kDa light chains respectively. Western blotting, using monospecific monoclonal antibodies, shows that only the heavy chain is recognised by the anti-MAP1B antibody and is not immunostained by either the MAP1A or MAP2 monoclonal antibodies. Purified MAP1B binds efficiently to both unpolymerised tubulin and polymerised tubulin and co-sediments with taxol-stabilised microtubules. Co-incubation experiments show that MAP2 can compete with MAP1B binding to microtubules, indicating common or overlapping sites. However, MAP1B binds to neither G-actin nor F-actin nor co-sediments with F-actin, suggesting that it is not an actin-binding protein.
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  • 92
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    Cell Motility and the Cytoskeleton 30 (1995), S. 310-323 
    ISSN: 0886-1544
    Keywords: mitosis ; mitotic apparatus ; sea urchin ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protein component of 62-kDa (p62) in the mitotic apparatus of the sea urchin embryo has been shown to be important for the proper progression of mitosis [Dinsmore and Sloboda, 1989: Cell 57:127-134]. To study the subcellular distribution of p62 during the cell cycle of sea urchin embryos, indirect immunofluorescence microscopy was used coupled to a modified detergent extraction procedure. The improved fluorescent images obtained by this procedure provide new information concerning the subcellular localization of p62 during the cell cycle that could not be obtained with previous conventional staining procedures [Johnston and Sloboda, 1992: J. Cell Biol. 119:843-854]. Using affinity purified antibodies to p62, we observed a cell cycle-dependent localization of p62 to the chromosomes/chromatin. Prior to nuclear envelope breakdown of the first or second cell cycle, p62 localizes to chromatin in the nucleus. During mitosis, p62 associates with the region of the spindle occupied by the microtubules of the mitotic apparatus. As anaphase proceeds, but before the nuclear envelope reforms, p62 becomes progressively associated with the chromosomes. Thus, p62 is incorporated into the forming interphase nucleus due to its association with chromosomes during late anaphase, rather than by active translocation into the newly formed daughter nuclei through the nuclear pores. The protein is not unique to marine embryos, as demonstrated by immunofluorescence of Y-1 cells, a mouse adrenal tumor cell line In these cells, the localization of p62 is similar to the localization of the protein in echinoderm embryos, suggesting its possible function in mitotic progression in mammalian somatic cells as well. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 93
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    Cell Motility and the Cytoskeleton 31 (1995) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 94
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    Cell Motility and the Cytoskeleton 31 (1995), S. 1-8 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: No Abstratct.
    Additional Material: 1 Ill.
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  • 95
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    Cell Motility and the Cytoskeleton 31 (1995), S. 9-21 
    ISSN: 0886-1544
    Keywords: neurofilament ; axoplasm ; axonal cytoskeleton ; giant axon ; squid ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have used axoplasm from the squid giant axon to investigate the effects of anionic and cationic polypeptides on the mobility and organization of axonal neurofilaments (NFs). Intact cylinders of axoplasm were extruded from squid giant axons into an excess volume of artificial axoplasm solution. In a previous study on the mobility of NFs in extruded axoplasm, we showed that these polymers disperse freely and diffusively into the surrounding solution, thereby expanding the axoplasmic cross-sectional area [Brown and Lasek, 1993: Cell Motil. Cytoskeleton 26:313-324]. In the present study, we found that 83nm-long (“long-chain”) polylysine, a synthetic multivalent cationic protein, inhibited the radial expansion of isolated axoplasm and condensed the axoplasm, thereby reducing the cross-sectional area. Equivalent concentrations of a 7nm-long (“short-chain”) polylysine did not inhibit the expansion of axoplasm and did not cause the axoplasm to condense. Inhibition of the expansion of axoplasm by long-chain polylysine was dependent on the polylysine concentration; condensation of axoplasm was observed at concentrations of 0.01 mg/ml (0.27 μM) or greater. Electron microscopy of the condensed axoplasm showed that the NFs were aligned side-by-side and in parallel in closely-packed bundles. Equivalent concentrations of 91nm-long (“long-chain”) polyglutamate, a synthetic multivalent anionic protein, partially inhibited the expansion of axoplasm but did not cause the NFs to bundle and did not cause the axoplasm to condense. These studies indicate that cationic proteins bind tightly to the highly charged anionic surfaces of NFs and can link them together into compact bundles in a charge-dependent and length-dependent manner. The tightly packed organization of these cross-linked NFs differs from the normal loose organization of NFs in healthy axons. However, tightly bundled NFs are sometimes found in certain neuropathologies, such as giant axonal neuropathy.
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  • 96
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 31 (1995) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 97
    ISSN: 0886-1544
    Keywords: Ascaris sperm ; motility ; computer-assisted motion analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Computer-assisted methods have been employed to obtain a high resolution description of pseudopod expansion, cellular translocation, and the subcellular dynamics of MSP fiber complexes in the motile sperm of the nematode Ascaris suum. Although Ascaris sperm translocating in a straight line or along a curved path do not retract their pseudopod or significantly alter pseudopod shape, they move in a cyclic fashion, with an average period between velocity peaks of 0.35 × 0.05 min, which is independent of the forward velocity of sperm translocation. Expansion is confined to a central zone at the distal edge of the pseudopod for sperm translocating in a straight line and to a left-handed or right-handed lateral zone in the direction of turning, for sperm translocating along a curved path. For cells translocating in a straight line, the branch points and kinks of MSP fiber complexes move in a retrograde direction in relation to the substratum at an average velocity of 11 μm per min which is independent of the forward velocity of sperm translocation. The distal (anterior) end of a fiber complex, however, moves distally at the speed of sperm translocation when it emanates from the expansion zone, but when it is displaced to a nonexpanding surface of the pseudopod, it stops moving distally. When a cell is anchored to the substratum and is, therefore, nonmotile, the velocity of fiber complexes moving in a retrograde direction doubles. The unique aspects of pseudopod and MSP fiber complex dynamics in Ascaris are compared to the dynamics of pseudopod formation and actin filament dynamics in traditional actin-based amoeboid cells, and the treadmill model for MSP polymerization is reassessed in light of the discovery that fiber complex branch points move proximally (posteriorly) at a fixed rate.
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  • 98
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    Cell Motility and the Cytoskeleton 31 (1995), S. 255-258 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
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  • 99
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    Cell Motility and the Cytoskeleton 31 (1995), S. 273-282 
    ISSN: 0886-1544
    Keywords: Peritoneal macrophages ; F-actin microfilament ; in situ hybridization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In mouse fibroblasts, at least five TM isoforms are identified and they can be grouped into the high (TM1, TM2, and TM3) and low molecular weight TM isoforms (TM4 and TM5). Suppression of one of the high molecular weight tropomyosin (TM) isoforms in nonmuscle cells is implicated to be one of the causes for disorganization of actin microfilament bundles and subsequent changes in cell motility and cell shape. In this study, we studied the expression of tropomyosin isoforms in macrophages that exhibit high motility and ability to change cell shape. Two-dimensional gel electrophoresis followed by Western blot analysis using polyclonal anti-TM antiserum revealed that the high molecular weight TM isoforms were lacking in both resident and activated mouse peritoneal macrophages. Analyses of newly synthesized TM isoforms, Northern blot analyses using isoform-specific cDNA probes, and immunostaining with monoclonal anti-TM antibody that recognizes only the high molecular weight TM isoforms also demonstrated that the syntheses of the high molecular weight TM isoforms (TM1, TM2, and TM3) were completely suppressed, whereas the low molecular weight TM isoforms (TM4 and TM5) were expressed in macrophages. These results indicate that macrophages intrinsically lack the high molecular weight TM isoforms. In order to obtain information about cellular localization of the low molecular weight TM isoforms in macrophages, they were immunostained with polyclonal anti-TM antiserum that recognizes both the high and low molecular weight TM isoforms. The results showed that the low molecular weight TM isoforms were co-localized with F-actin in punctate and short fibrous structures. In addition, we performed in situ hybridization analysis to examine localizations of the TM mRNAs in fibroblasts and macrophages. The results showed that TM mRNAs were localized throughout the cytoplasm. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 100
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    Cell Motility and the Cytoskeleton 31 (1995), S. 259-272 
    ISSN: 0886-1544
    Keywords: microtubules ; transfection ; hemagglutinin antigen ; autoregulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A Chinese hamster β-tubulin cDNA, engineered to express a 9 amino acid epitope from the influenza hemagglutinin antigen (HA), was transfected into Chinese hamster ovary (CHO) cells. The recombinant protein (HAβ1-tubulin) appeared to behave normally by the following criteria: immunofluorescence indicated that HAβ1-tubulin incorporated into all classes of interphase and spindle microtubules as well as microtubule organizing centers. The sensitivity of the cells expressing HAβ1-tubulin to Colcemid and taxol was unchanged. A 210 kD microtubule associated protein (MAP) remained associated with microtubules that incorporate HAβ1-tubulin. The synthesis of both endogenous β-tubulin and HAβ1-tubulin was repressed by colchicine. The HAβ1-tubulin incorporated into microtubules to the same extent as the endogenous β-tubulin, and the overall extent of microtubule assembly in transfected cells was unchanged. Finally, trasfected cells had normal growth rates and morphologies. When effects on endogenous tubulin production were measured, it was found that expression of the HAβ1-tubulin reduced the synthesis of endogenous wild-type β-tubulin but increased the synthesis of α-tubulin. At steady state, a small increase in total tubulin consistent with the increased synthesis of α-tubulin was found. The results indicate that expression of excess exogenous β-tubulin perturbs the synthesis of endogenous α-tubulin in a manner that is not easily explained by current models of tubulin regulation. The changes in tubulin synthesis along with degradation of excess tubulin subunits may reflect mechanisms that exist to ensure coordinate levels of α- and β-tubulin for assembly. © 1995 Wiley-Liss, Inc.
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