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  • 1
    Electronic Resource
    Electronic Resource
    Macronuclear chromatin of Blepharisma japonicum compared to that of Tetrahymena pyriformis (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 111 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The macronuclear chromatin of the ciliate Blepharisma japonicum was studied by electrophoretic and immunological techniques as well as by micrococcal nuclease digestion and circular dichroism spectroscopy. Under these experimental conditions the macronuclear chromatin of B. japonicum was compared to that of Tetrahymena pyriformis. Data obtained through this analysis showed that the macronuclear chromatin of B. japonicum is structurally more relaxed than that of T. pyriformis. A perchloric acid soluble polypeptide, referred to as P3, is the only polypeptide of B. japonicum chromatin to appear immunologically related to the H1 histone of T. pyriformis. It is suggested that this P3 polypeptide in B. japonicum should be considered functionally equivalent to the T. pyriformis H1 histone, even though it differed from it both in terms of molecular mass and relative concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06402.x
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  • 2
    Electronic Resource
    Electronic Resource
    Cytochemistry of late ovarian chambers of Drosophila melanogaster (1976)
    Springer
    Histochemistry and cell biology 48 (1976), S. 325-334 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Late ovarian chambers of Drosophila melanogaster have been examined by ultrastructural cytochemistry in an attempt to characterize some of the transformations which precede the completion of oogenesis. From stage 11 onward peroxidase activity is present in the endoplasmic reticulum of both nurse cells and oocyte, as well as in the egg-covering precursors of the columnar follicle cells. Catalase activity is restricted to the very last stages of oogenesis (stage 13–14) and appears to be located in membrane-bound organelles of the ooplasm which are continuous with the endoplasmic reticulum. Because of the presence of catalase as well as by their structural appearance, these organelles are to be identified as microperoxisomes. Catalase activity becomes cytochemically detectable in the ooplasm somehow in coincidence with the formation of glycogen. Furthermore, glycogen is first formed in intimate association with alpha-1 yolk platelets. On the basis of these findings it is suggested that glycogen synthesis occurs by a process of gluconeogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499249
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  • 3
    Electronic Resource
    Electronic Resource
    Osmium Zinc Iodide staining of Golgi elements in oocytes of Triturus cristatus (1976)
    Springer
    Cell & tissue research 172 (1976), S. 121-131 
    Details
    ISSN: 1432-0878
    Keywords: Yolk ; Oocyte (Triturus cristatus) ; Vitellogenesis ; Pinocytosis ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Developing oocytes of the newt Triturus cristatus were studied in order to clarify the role played by the Golgi apparatus in the formation of yolk. The cytochemical method used for this purpose was that of Maillet (1968) which employs an Osmium Zinc Iodide (OZI) complex. Previtellogenic oocytes reveal a pattern of OZI staining only after hormonal (HCG) stimulation, following which both the Golgi apparatus and the multivesicular bodies are stained. Vitellogenic oocytes taken from non-hormonally stimulated females reveal OZI deposits in a number of vesicles peripheral to the Golgi apparatus as well as within the superficial layer of the forming yolk platelets. Following hormone stimulation, many of the Golgi apparatus located in the central ooplasm of vitellogenic oocytes have all their cisternae blackened by the OZI deposits; other apparatuses, more peripherally located, remain essentially unchanged in their staining pattern. Further, a large number of OZI stained vesicles becomes visible in the vicinity of the Golgi apparatus and within the superficial layer of the forming yolk platelets. The present findings are interpreted as indicating the occurrence of fusion between Golgi derived vesicles and forming yolk platelets. It is also suggested that the vesicles in question function as carriers of Golgi produced enzymes which are presumably required to accomplish the final elaboration of the yolk material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226053
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  • 4
    Electronic Resource
    Electronic Resource
    Confocal scanning laser microscopy of the follicular epithelium in ovarioles of the stick insect Carausius morosus (1998)
    Springer
    Cell & tissue research 293 (1998), S. 551-561 
    Details
    ISSN: 1432-0878
    Keywords: Key words Follicular epithelium ; Insect ovarioles ; Confocal laser microscopy ; Carausius morosus (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Ovarian follicles of the stick insect Carausius morosus were analyzed by confocal laser microscopy and immunocytochemistry with a view to studying cell polarity in the follicular epithelium. Such probes as anti-α-tubulin antibodies and Rh-phalloidin were employed to establish how the follicle cell cytoskeleton changes during ovarian development. Data show that α-tubulin prevails over the basal end, while F-actin appears more abundant along the apical end of the follicle cells. This finding was further corroborated by immunogold cytochemistry, showing that label along the basal end is primarily associated with microtubules, while that along the apical end is due to follicle cell microvilli interdigitating with the oocyte plasma membrane. A monoclonal antibody specifically raised against a vitellin polypeptide was used to investigate the role the follicular epithelium might play in relation to vitellogenin (Vg) uptake by the oocyte. Data show that under these conditions label is restricted to the intercellular channels of the follicular epithelium, thus providing further support to the notion that Vg enters the oocyte through the extracellular pathway leading from the basement lamina to the oocyte surface. By contrast, the use of a monoclonal antibody raised against a fat-body-derived protein of 85 kDa that is specifically sulfated within the follicle cells provides evidence for the existence of an alternative way of gaining access to the oocyte surface, that is by transcytosis through the follicular cell epithelium. These findings confirm our earlier observations on stick insect ovarioles whereby polarization in the follicular epithelium is primarily addressed to sustain a transcytotic vesicular traffic between opposite poles of the follicle cell of Vg toward the oocyte surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051147
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  • 5
    Electronic Resource
    Electronic Resource
    The follicle cell-oocyte interaction in ovarian follicles of the stick insect Bacillus rossius (Rossi): (Insecta: Phasmatodea) (1985)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 37-49 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Developing ovarian follicles of Bacillus rossius have been examined ultrastructurally in an attempt to understand how inception of vitel-logenesis is controlled. Early vitellogenic follicles are characterized by a thick cuboidal epithelium that is highly interlocked with the oocyte plasma membrane. Gap junctional contacts are present both at the follicle cell/oocyte interface and in between adjacent follicle cells. In addition, microvilli of follicle cells protrude deeply into the cortical ooplasm of these early vitellogenic oocytes. With the onset of vitellogenesis, wide intercellular spaces appear in the follicle cell epithelium and at the follicle cell/oocyte interface. Gap junctions become progressively reduced both on the follicle cell surface and on the oocyte plasma membrane. Microvilli from the two cell types no longer interlock.From a theoretical standpoint each of the two structural differentiations present at the follicle cell/oocyte interface - gap junctions and follicle cell microvilli - could potentially trigger inception of vitellogenesis. Gap junctions might permit the passage of a regulatory molecule, transferring from follicle cells to oocyte, which would control the assembly of coated pits on the oocyte plasma membrane. Alternatively cell interaction via microvilli might induce the appearance of coated pits, thus creating a membrane focus for vitellogenin receptors. Both possibilities are discussed in relation to current literature.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051850103
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  • 6
    Electronic Resource
    Electronic Resource
    In vitro induced pinocytotic activity by a juvenile hormone analogue in oocytes of Drosophila melanogaster (1979)
    Springer
    Cell & tissue research 203 (1979), S. 241-247 
    Details
    ISSN: 1432-0878
    Keywords: Pinocytotic activity ; Juvenile hormone ; Drosophila ; Oocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pinocytotic activity has been analyzed in Drosophila oocytes following either in vivo or in vitro exposure to horseradish peroxidase. The enzyme tracer gains access to the yolk spheres only when supplied to the oocyte in vivo. In oocytes cultured in vitro, peroxidase remains restricted to the residual coated vesicles and to the tubular profiles formed in excess in the cortical ooplasm. In an attempt to induce peroxidase uptake by oocytes cultured in vitro, various incubations were tested. Among these, hemolymph from both sexes is capable of promoting peroxidase uptake up to a level comparable to that detectable in vivo. On the other hand, fat body extracts fail to promote such cellular activity. Finally, the juvenile hormone analogue ZR-515 is shown to be the only factor required to promote pinocytotic activity under the experimental conditions tested. The observations are interpreted to indicate that vitellogenin has no inductive role on pinocytosis but simply acts by adhering to the forming coated vesicles which in turn are produced by the oolemma in response to the action of juvenile hormone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237238
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  • 7
    Electronic Resource
    Electronic Resource
    Intercellular bridges in ovarian follicle cells of Drosophila melanogaster (1978)
    Springer
    Cell & tissue research 186 (1978), S. 413-422 
    Details
    ISSN: 1432-0878
    Keywords: Oogenesis ; Drosophila ; Intercellular bridges ; Synchronous development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intercellular bridges have been detected in ovarian follicle cells of Drosophila melanogaster. These bridges occur widely between follicle cells of previtellogenic chambers, while, in vitellogenic chambers, they become restricted to the columnar follicle cells. Usually, only one bridge is detectable between adjacent follicle cells, but a single cell may form two cytoplasmic continuities. The fine structure of the intercellular bridges is similar to that previously described in the development of Drosophila. The bridge wall consists of two layers of which the more external is more electron dense and thinner than the inner one. The role played by the intercellular bridges in the determination of a synchronous differentiation of the linked follicle cells is discussed in relation to the known behaviour of these cells in the secretion of the egg covering precursors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224931
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  • 8
    Electronic Resource
    Electronic Resource
    Yolk polypeptide secretion and vitelline membrane deposition in a female sterile Drosophila mutant (1985)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 133-150 
    Details
    ISSN: 0192-253X
    Keywords: vitellogenesis ; Drosophila melanogaster ; egg shell ; oogenesis ; vitellogenin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ovarian follicle cells of wild type Drosophila melanogaster simultaneously secrete yolk polypeptides (YP1, YP2 and YP3) and vitelline membrane proteins. In order to understand the relationship between these two secretory activities, we have investigated the ultrastructure of a female sterile mutation that alters YP1 secretion and vitelline membrane deposition. Homozygous fs(1)1163 females lay eggs that collapse and contain reduced quantities of YP1. Secretory granules in follicle cells contain an electron-translucent component that is assembled into the developing vitelline membrane in both mutant and wild-type ovaries, and an electron-dense component that disperses after secretion in wild-type ovaries. Mutant ovaries differ from wild-type by (1) having larger secretory granules (2) forming clumps of the dense secretory component within the developing vitelline membrane (3) accumulating more tubules in the cortical ooplasm of vitellogenic oocytes, and (4) possessing altered yolk spheres. Mutant ovaries implanted into wild-type hosts showed no improvement in the secretory granules and slight improvement in the vitelline membrane clumps but amelioration of the oocyte phenotypes. Since genetic evidence suggests that the fs(1)1163 mutation resides in or near the Yp1 gene and biochemical data show that the mutation alters YP1 structure, we conclude that the ultrastructural phenotypes are due to a structurally abnormal YP1 in the mutant. The alteration in vitelline membrane structure caused by the dense clumps could account for collapsed eggs and, hence, the female sterility of the mutant.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020060206
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  • 9
    Electronic Resource
    Electronic Resource
    Postendocytic vitellin processing in ovarian follicles of the stick insect Carausius morosus (Br.) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 24 (1993), S. 93-111 
    Details
    ISSN: 0739-4462
    Keywords: vitellogenesis ; endocytosis ; ovarian development ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Newly laid eggs of the stick insect Carausius morosus contain two native vitellins (Vit A and Vit B). Under denaturing conditions, these vitellins resolved into 3 (A1, A2, and A3) and 2 (B1 and B2) polypeptides. All of these polypeptides had counterparts in the female hemolymph from which they were shown to be derived by in vivo labelling. During ovarian development, the 2 vitellins changed both in charge and polypeptide composition. In EV and LV follicles, Vit A resolved into 4 distinct vitellin polypeptides (A0, A1, A2 and A3). Using a panel of monoclonal antibodies, polypeptide A0 proved to be immunologically related to polypeptide A2. In follicles about to begin choriongenesis, polypeptide A3 was gradually replaced by a lower Mr polypeptide. Over the same time period, polypeptide B1 changed in charge, but not in Mr. To confirm the existence of a polypeptide processing in C. morosus, ovarian follicles of different developmental stages were exposed in vivo to [35S]-methionine from 6 to 72 h. Data showed that A0 and B1 were the polypeptides most heavily labelled after short time exposures to the radioisotope. Polypeptides B2 and A3 were also labelled to some extent. With progressively longer exposures, polypeptides A1 and A2 also became labelled. In vivo exposure to [3H]-GlcNAc caused all vitellin polypeptides to become heavily labelled. Autoradiographic analysis of ovarian follicles labelled this way showed that, during development, radioactivity was gradually transferred from newly formed yolk spheres in the cortical ooplasm to the central ooplasm. Data were interpreted as suggesting a causal relationship between polypeptide processing and progressive yolk sphere fusion to yield the central ooplasm. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940240204
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