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  • 1
    Electronic Resource
    Electronic Resource
    A new senescence-inducing mitochondrial linear plasmid in field-isolated Neurospora crassa strains from India (1991)
    Springer
    Current genetics 19 (1991), S. 129-137 
    Details
    ISSN: 1432-0983
    Keywords: Senescence ; Plasmid ; Neurospora ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several field-collected strains of Neurospora crassa from the vicinity or Aarey, Bombay, India, are prone to precocious senescence and death. Analysis of one strain, Aarely-1e, demonstrated that the genetic determinants for the predisposition to senescence are maternally inherited. The senescence-prone strains contain a 7-kb, linear, mitochondrial DNA plasmid, maranhar, which is not present in long-lived isolates from the same geographical location. The maranhar plasmid has inverted terminal repeats with protein covalently bound at the 5′ termini. Molecular hybridization experiments have demonstrated no substantial DNA sequence homology between the plasmid and the normal mitochondrial (mtDNA) and nuclear genomes of long-lived strains of N. crassa. Integrated maranhar sequences were detected in the mtDNAs of two cultures derived from Aarey-1e, and mtDNAs with the insertion sequences accumulated during subculturing. Nucleotide sequence analysis of cloned fragments of the two insertion sequences demonstrates that that they are flanked by long inverted repeats of mtDNA. The senescence syndrome of the maranhar strains, and the mode of integration of the plasmid, are reminiscent of those seen in the kalilo strains of N. intermedia. Nonetheless, there is no detectable nucleotide sequence homology between the maranhar and kalilo plasmids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326294
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  • 2
    Electronic Resource
    Electronic Resource
    Plasmid diversity in senescent and nonsenescent strains of Neurospora (1993)
    Springer
    Molecular genetics and genomics 237 (1993), S. 177-186 
    Details
    ISSN: 1617-4623
    Keywords: Senescence ; Linear plasmids ; Circular plasmids ; Neurospora ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A sample of 171 natural isolates of Neurospora crassa and Neurospora intermedia was tested for senescence. Of these, 28 strains senesced within the duration of the experiment. These senescent strains, together with a selection of nonsenescent strains, were examined for the presence of mitochondrial plasmids. This was done by digesting mitochondrial DNA preparations with proteinase K, and running these samples on agarose gels. Most of the strains examined, both senescent and nonsenescent, contained plasmids, many of them new. Some new plasmids were linear, as inferred from their resistance to 5′ exonuclease and sensitivity to 3′ exonuclease. New circular plasmids were also found. Some strains carry several plasmids, and mixtures of circular and linear elements were common. A cross-homology study was performed on a sample of plasmid-bearing strains, and several cases of apparent relatedness were found, some between strains from distant geographical locations. Linear plasmids homologous to the maranhar linear senescence plasmid were quite common. A new member of the LaBelle circular plasmid homology group was found. In the sample tested for homology, no strains contained elements related to the kalilo linear senescence plasmid. The relationship of the new plasmids to senescence is not known. In addition to plasmid monomers, several different types of derivatives were found. The kalilo linear plasmid was found to occur in linear and circular forms of low mobility, presumed to be giant concatamers, and, in some strains, variant sibling structures and ladders of short derivatives were found. Circular plasmids also gave rise to extensive ladders on electrophoresis, probably representing different relaxation states and head-to-tail concatameric series. Some such forms migrated more slowly than mitochondrial DNA. One unique type of plasmid modification observed was a pair of linear elements that had apparently arisen de novo which showed homology to a circular plasmid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282799
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  • 3
    Electronic Resource
    Electronic Resource
    Markers of prognosis in breast cancer - the relationship between binding of the lectin HPA and histological grade, SPF, and ploidy (1993)
    Springer
    Breast cancer research and treatment 25 (1993), S. 247-256 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; glycosylation ; HPA ; Helix pomatia lectin ; prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Abnormal cellular glycosylation as demonstrated by the binding of a lectin fromHelix pomatia (HPA) to paraffin-embedded sections has been shown in several studies to be associated with aggressive biological behaviour and poor long-term patient prognosis in breast cancer. This study aims to address the possibility that expression of the HPA binding ligand may be of prognostic significance through an association with increased cellular proliferation (as measured by S-phase fraction and histological grade), anaplasia (reflected in histological grade), or ploidy (DNA index). In a 24 year retrospective study, paraffin-embedded sections of 366 primary breast cancers were stained for binding of HPA. All tumours were assessed for histological grade. Flow cytometry was performed on all cases for which sufficient tumour tissue was available (358/366 cases) and S-phase fraction (SPF) and ploidy calculated. Data regarding patient age at diagnosis, nodal status, and tumour size were also recorded. Life table analyses revealed survival advantage for HPA ‘non stainers’ in comparison to ‘stainers’ (p〈 0.001); for patients with tumours of low grade vs. high grade (p〈0.001); and for those with tumours of low SPF vs. high SPF (p〈0.001). No survival advantage was shown for those with diploid vs. aneuploid tumours (p= 0.17). No association was apparent between HPA binding and grade, SPF, or ploidy (Chi squared values not significant). This was confirmed by multivariate analysis in which nodal status, tumour size, and SPF were independently predictive of survival. There was no confounding effect of grade, SPF, or ploidy upon the correlation between survival and HPA binding. HPA was, however, not independently predictive owing to its strong association with nodal status. The results of this study suggest that the prognostic significance of altered glycosylation, as detected by HPA binding, is unlikely to be through an association with proliferative rate, degree of anaplasia, or cellular ploidy, but may rather be through a direct association with the presence of nodal metastases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689839
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  • 4
    Electronic Resource
    Electronic Resource
    Glycosylation patterns of the human colon cancer cell line HT-29 detected byHelix pomatia agglutinin and other lectins in culture, in primary tumours and in metastases in SCID mice (1994)
    Springer
    Clinical & experimental metastasis 12 (1994), S. 398-404 
    Details
    ISSN: 1573-7276
    Keywords: colon cancer ; glycosylation ; Helix pomatia agglutinin ; metastasis ; SCID mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Human colonic cancer cells (HT-29, 10 7 cells/dose) were injected subcutaneously between the scapulae of 19 severe combined immunodeficient (SCID) mice. After 19 days, large tumours had developed in 18 out of the 19 animals and the mice were then killed. Metastases were detected in the lungs of 16 animals but not in other organs investigated. Surgical removal of the primary tumour in another group of five animals led to a prolonged survival and further growth of metastases in the lungs. HT-29 injection into the tail vein (n=5)resulted in colonization of the lungs. The tumours that developed in the animals were signet cell carcinomas; these forms are not seen in HT-29 cells in culture. Glycoconjugate expression of the tumours was assessed using several lectins. In many cases the results indicated a stability of lectin-binding patterns from cell culture conditions to implantation into the SCID mice. This was true for the lectin Helix pomatia agglutinin (HPA), the binding of which is associated with a high metastatic potential in some human tumours, including colon cancer. All the primary tumours and metastases were HPA positive. This xenograft tumour model seems to be a clinically relevant system for the study of glycoconjugate expression in human colon cancer cells and their metastases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01755883
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  • 5
    Electronic Resource
    Electronic Resource
    Sarcomeric myosin heavy chain expressed in nonmuscle cells forms thick filaments in the presence of substoichiometric amounts of light chains (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 26 (1993), S. 192-204 
    Details
    ISSN: 0886-1544
    Keywords: myofibrillogenesis ; myosin heavy chain ; myosin light chains ; transfection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Central to the function of myosin is its ability to assemble into thick filaments which interact precisely and specifically with other myofibrillar proteins. We have established a novel experimental system for studying myofibrillogenesis using transient transfections of COS cells, a monkey kidney cell line. We have expressed both full-length rat α cardiac myosin heavy chain (MHC) and a truncated heavy meromyosin-like α MHC (sHMM) and shown that immunoreactive MHC proteins of the expected sizes were detected in lysates of transfected cells. Surprisingly, the full-length MHC formed large spindle-shaped structures throughout the cytoplasm of transfected cells as determined by immunofluorescence microscopy. The structures were not found in cells expressing the sHMM construct, indicating that their formation required an MHC rod. The spindle-shaped structures ranged in length from approximately 1 μm to over 20 μm in length and were birefringent suggesting that they are ordered arrays of thick filaments. This was confirmed by electron microscopic analysis of the transfected cells which revealed arrays of filamentous structures approximately 12 nm in diameter at their widest point. In addition, the vast majority of transfected MHC did not associate with the endogenous nonmuscle myosin light chains, demonstrating that myosin thick filaments can form in the absence of stoichiometric amounts of myosin light chains. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970260303
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of the dilution rate on CHO cell physiology and recombinant interferon-γ production in glucose-limited chemostat culture (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1077-1085 
    Details
    ISSN: 0006-3592
    Keywords: chemostat ; glucose limitation ; glycosylation ; CHO cells ; interferon-γ ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiology of a recombinant Chinese hamster ovary cell line in glucose-limited chemostat culture was studied over a range of dilution rates (D = 0.008 to 0.20 h-1). The specific growth rate (μ) deviated from D at low dilution rates due to an increased specific death rate. Extrapolation of these data suggested a minimum specific growth rate of 0.011 h-1 (μmax = 0.025 h-1) The metabolism at each steady state was characterized by determining the metabolic quotients for glucose, lactate, ammonia, amino acids, and interferon-γ (IFN-γ). The specific rate of glucose uptake increased linearly with μ, and the saturation constant for glucose (Ks) was calculated to be 59.6 μM. There was a linear increase in the rate of lactate production with a higher yield of lactate from glucose at high growth rates. The decline in the rate of production of lactate, alanine, and serine at low growth rate was consistent with the limitation of the glycolytic pathway by glucose. The specific rate of IFN-γ production increased with μ in a manner indicative of a growth-related product. Despite changes in the IFN-γ production rate and cell physiology, the pattern of IFN-γ glycosylation was similar at all except the lowest growth rates where there was increased production of nonglycosylated IFN-γ. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420909
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  • 7
    Electronic Resource
    Electronic Resource
    Glucose-limited chemostat culture of chinese hamster ovary cells producing recombinant human interferon-γ (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 327-335 
    Details
    ISSN: 0006-3592
    Keywords: Chinese hamster ovary ; interferon-γ ; chemostat culture ; glycosylation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Chinese hamster ovary (CHO) cell line expressing recombinant human interferon-γ (IFN-γ) was grown under glucose limitation in a chemostate at a constant dilution rate of 0.015 h-1 with glucose feed concentrations of 2.75 mM and 4.25 mM. The changes in cell concentration that accompanied changes in the glucose feed concentration indicated that the cells were glucose-limited. The cell yield on glucose remained constant, but there was a decline in residual glucose concentration and a reduced lactate yield from glucose in the latter stages of the culture. The consumption rates for many of the essential amino acids were increased later in the culture. The volumetric rate of interferon-γ production was maintained throughout the course of this culture, indicating that IFN-γ expression was stable under these conditions. However, the specific rate of IFN-γ production was significantly lower at the higher glucose feed concentration. Under glucose limitation, the proportion of fully glycosylated IFN-γ produced by these cells was less than that produced in the early stages of batch cultures. The proportion of fully glycosylated IFN-γ increased during transient periods of glucose excess, suggesting that the culture environment influences the glycosylation of IFN-γ.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390311
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  • 8
    Electronic Resource
    Electronic Resource
    The architecture of adventitial elastin in the canine infrarenal aorta (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 230 (1991), S. 86-96 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Although the artery wall consists of three distinct layers, only the structures of the intima and media have been well characterized. The adventitia has generally been overlooked. Our examination focused on the organization of elastin and collagen which are the major components of this tunic. Canine infrarenal aortas were excised, stretched to their in vivo length, then pressure fixed in formalin. Transverse, longitudinal, and frontal sections were prepared with specific elastin and collagen stains. Areas of adventitia in these sections were examined with LM, and interconnections between collagen and elastin were photographed at various magnifications. Subsequently, the slides were fractured for attachment to SEM stubs, and the coverslips were demounted. The identical areas were then examined with SEM using the LM micrographs as a guide to identify elastin and collagen. Whole mount aortic ring preparations were digested in formic acid for 72 and 96 h at 45°C to confirm adventitial elastin architecture. The adventitia was organized in alternating lamellae of collagen and elastin. The elastin lamellae consisted of continuous sheets of elastin with a longitudinal fibrillar substructure. Finer circumferential elastin fibers were also identified. These attached to both longitudinal elastin and adjacent collagen lamellae. Collagen lamellae were arranged in broad corrugated bands of fibrils. The unique architecture of the adventitia may explain some of the visco-elastic properties of the aorta in both normal and pathologic states.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092300109
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  • 9
    Electronic Resource
    Electronic Resource
    Zona drilling enhances fertilization by mouse caput epididymal sperm (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 332-336 
    Details
    ISSN: 1040-452X
    Keywords: Caput epididymis ; Micromanipulation ; In vitro fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spermatozoa from the caput epididymis are known to be much less capable of fertilization when compared to sperm from more distal segments of the epididymis. The purpose of this study was to determine if two micromanipulative techniques, zona drilling (ZD) and a modification of partial zona dissection (PZD), could be used to enhance fertilization with caput epididymal sperm. A mouse in vitro fertilization model was used. Inseminating oocytes with 500-1,000 sperm/oocyte from the cauda epididymis as a control resulted in fertilization of 98 of 300 (32.6%) oocytes. Of those fertilized, 47 developed to the blastocyst stage (47.9%). Caput sperm fertilized 13 of 116 (11.2%) nonmanipulated oocytes. Only 1 of 13 developed into a blastocyst, while with oocyte ZD, caput sperm fertilized 24 of 144 (16.7%) oocytes, 50% of those fertilized developing to blastocyst (P=0.0129). When modified PZD was performed on oocytes, only one of 23 was fertilized, with no blastocyst development. These results indicate that acid Tyrode ZD enhances both fertilization and early embryonal development when caput epididymal sperm are used for insemination. These mouse studies suggest that ZD or other micromanipulation techniques may prove clinically useful in men with proximal epididymal obstruction where only caput sperm are available.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080270407
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  • 10
    Electronic Resource
    Electronic Resource
    Electron microscopic studies of magnetosomes in magnetotactic bacteria (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 389-401 
    Details
    ISSN: 1059-910X
    Keywords: Biomineralization ; Greigite ; Magnetite ; Pyrite ; Single-magnetic-domain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Electron microscopic studies on magnetosomes in magnetotactic bacteria have revealed much information on their composition, structure, and even the formation of their mineral phase. The mineral phases of the magnetosomes are of two general types: iron oxides and iron sulfides. Iron oxide-type magnetosomes contain particles of the ferrimagnetic mineral magnetite (Fe3O4) while the iron sulfide-type contain ferrimagnetic greigite (Fe3S4), greigite and non-magnetic pyrite (FeS2), or possibly ferrimagnetic pyrrhotite (Fe7S8). Regardless of their composition, the crystalline particles in magnetosomes have a narrow size range: approximately 35 to 120 nm. Magnetite crystals in this size range are single-magnetic-domains and confer a permanent magnetic dipole moment to the cell. The single-domain size range for greigite is not known but is probably similar to that for magnetite.The morphology of the particles in the bacterial magnetosomes appears to be species-specific. Morphologies of magnetite crystals in different species of magnetotactic bacteria include cubooctahedra, parallelepipedal (truncated hexahedral or octahedral prisms), and tooth- or bullet-shaped (anisotropic). Morphologies of greigite particles include cubo-octahedra and rectangular prismatic. The greigite-pyrite particles are generally pleomorphic with no consistent crystalline morphology. A membrane has been shown to surround the particles in some organisms and may be involved in the formation of the crystalline phase while also providing physical constraints on the size and the shape of the crystal. These results clearly indicate that the biomineralization process involved in the bacterial magnetosome, a good example of a self-assembled structure on a nanometer scale, is highly controlled by the organism. © 1994 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070270505
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