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  • 1
    Electronic Resource
    Electronic Resource
    Asymmetrically distributed ecdysteroid-related antigens in follicles and young embryos of Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 295-302 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Oogenesis ; Embryogenesis ; Ecdysteroids ; Localized factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have produced monoclonal and polyclonal antibodies against an antigen that is asymmetrically distributed in mature oocytes of Drosophila melanogaster. During late oogenesis and early embryogenesis the antigen undergoes dramatic changes in its cellular localization: until about 2.5 h before completion of oogenesis it is homogeneously distributed in the cytoplasm, then it becomes localized in granules that are more numerous in posterior than in anterior peripheral positions of the ooplasm. The germ plasm is void of the antigen. Shortly after egg deposition the antigen is released from the granules and forms a shallow temporary gradient in the egg. Later during embryogenesis the antigen is associated with the yolk-containing cytoplasm. At the syncytial blastoderm stage it is also detected in the peripheral nuclei. Preliminary evidence suggests that the antigen is an ecdysteroid-related molecule. Five different anti-ecdysone antisera were found to bind to the same antigen or to an antigen with the same localization as our monoclonal antibody. In pattern mutants affecting anteroposterior polarity, the described asymmetrical distribution of the antigen is abnormal. In the mutant BicD, for example, which leads to the formation of two abdomina of opposite polarity, the antigen-containing granules are distributed homogeneously in mature oocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377396
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  • 2
    Electronic Resource
    Electronic Resource
    Morphogenesis of the micropylar apparatus in ovarian follicles of the fungus gnatBradysia tritici (syn.Sciara ocellaris) (1990)
    Springer
    Development genes and evolution 199 (1990), S. 146-155 
    Details
    ISSN: 1432-041X
    Keywords: Micropylar apparatus ; Bradysia tritici ; Oogenesis ; Follicle cells ; Egg shell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure and morphogenesis of the micropylar apparatus (MPA) have been studied in follicles of the fungus gnatBradysia tritici. The MPA is formed by a group of follicle cells located at the anterior pole of the single large nurse cell. In principle, the MPA consists of two thickened plates made of vitelline membrane material, the lower (LMP) and upper micropylar plate (UMP). The former is synthesized by 3 follicle cells, the latter by 4 different follicle cells. The micropylar channel system consists of a central channel with a single outer orifice and three branches which reach the plasma membrane of the oocyte. The branches are moulded by cellular extensions of the LMP-forming cells which are sandwiched between the two growing micropylar plates. Microtubuli and microfilaments were identified parallel to the long axis of the cellular extensions. At the time of MPA synthesis the nurse cell is still large and hence the MPA-forming cells have no contact to the oocyte. At the end of oogenesis when the regression of the nurse cell is completed, the MPA becomes connected to the other parts of the egg shell. At this time an ultrastructurally homogeneous region forms in the adjacent ooplasm (“cytoplasmic cone”). The possible relevance of these cytological observations for the control of development is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01681487
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  • 3
    Electronic Resource
    Electronic Resource
    Localized synthesis of specific proteins during oogenesis and early embryogenesis inDrosophila melanogaster (1979)
    Springer
    Development genes and evolution 187 (1979), S. 151-165 
    Details
    ISSN: 1432-041X
    Keywords: Oogenesis ; Embryogenesis ; Two-dimensional gels ; Protein synthesis ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protein synthesis in egg follicles and blastoderm embryos ofDrosophila melanogaster has been studied by means of two-dimensional gel electrophoresis. Up to 400 polypeptide spots have been resolved on autoradiographs. Stage 10 follicles (for stages see King, 1970) were labelled in vitro for 10 to 60 min with35S-methionine and cut with tungsten needles into an anterior fragment containing the nurse cells and a posterior fragment containing the oocyte and follicle cells. The nurse cells were found to synthesize a complex pattern of proteins. At least two proteins were detected only in nurse cells but not in the oocyte even after a one hour labelling period. Nurse cells isolated from stages 9, 10 and 12 follicles were shown to synthesize stage specific patterns of proteins. Several proteins are synthesized in posterior fragments of stage 10 follicles but not in anterior fragments. These proteins are only found in follicle cells. No oocyte specific proteins have been detected. Striking differences between the protein patterns of anterior and posterior fragments persist until the nurse cells degenerate. In mature stage 14 follicles, labelled in vivo, no significant differences in the protein patterns of isolated anterior and posterior fragments could be detected; this may be due to technical limitations. At the blastoderm stage localized synthesis of specific proteins becomes detectable again. When blastoderm embryos, labelled in vivo, are cut with tungsten needles and the cells are isolated from anterior and posterior halves, differences become apparent. The pole cells located at the posterior pole are highly active in protein synthesis and contribute several specific proteins which are found exclusively in the posterior region of the embryo. In this study synthesis of specific proteins could only be demonstrated at those developmental stages which are characterized by the presence of different cell types within the egg chamber, while no differences were detected when stage 14 follicles were cut and anterior and posterior fragments analyzed separately. The differences in the pattern of protein synthesis by pole cells and blastoderm cells indicate that even the earliest stages of determination are reflected by marked changes at the biochemical level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848268
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  • 4
    Electronic Resource
    Electronic Resource
    Yolk synthesis in ovarian follicles ofDrosophila (1980)
    Springer
    Development genes and evolution 189 (1980), S. 221-224 
    Details
    ISSN: 1432-041X
    Keywords: Intrafollicular yolk synthesis ; Vitellogenesis ; Drosophila follicle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The autonomous synthesis of yolk proteins in ovarian follicles ofDrosophila melanogaster was analyzed. Vitellogenic follicles were labelled with35S-methionine in vitro and the newly synthesized yolk proteins were separated by SDS-polyacrylamide gel electrophoresis. Possible contamination of the follicle preparations caused by adhering fat body cells could be excluded by culturing follicles in males prior to labelling in vitro. When labelled follicles were cut at the nurse cell/oocyte border the three yolk proteins (YP1, YP2, YP3) were found only in posterior fragments containing ooplasm and follicle cells, whereas two radioactive protein bands (A and B) were detected in nurse cells (anterior fragments). The yolk proteins of these five bands were characterized by peptide mapping. Band A protein, migrating a little more slowly than YP2, is closely related to both YP1 and YP2 while band B contains a yolk protein which is very similar to YP3. Hence, the nurse cells have been identified as a site of vitellogenin synthesis within the ovary ofDrosophila.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00868681
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  • 5
    Electronic Resource
    Electronic Resource
    Oosome formation during in vitro oogenesis inBradysia tritici (syn.Sciara ocellaris) (1985)
    Springer
    Development genes and evolution 194 (1985), S. 404-410 
    Details
    ISSN: 1432-041X
    Keywords: Oosome formation ; In vitro cultivation ; Oogenesis ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of follicles fromBradysia tritici (syn.Sciara ocellaris) during in vitro culture was studied. When follicles are isolated from 12-h-old females and placed in Robb's R-14 medium, their nurse cells regress with the same kinetics as in vivo and a histologically normal oosome forms at the posterior pole of the oocyte. Protein synthesis during in vitro development was studied by labelling follicles for 15 min and culturing them in vitro until the oosome had formed (28 h after eclosion of the donor). The time-course of protein labelling was defined by studying the incorporation kinetics of3H-amino acids into TCA-precipitable material; 50% of the radioactivity in the follicles was incorporated into TCA-precipitable material in less than 30 min. Autoradiographs of follicles labelled at different stages of oogenesis always showed a labelled oosome even if the labelling period was hours before oosome formation. These results indicate that the synthesis of oosome material starts long before the oosome forms at the end of vitellogenesis. Oosome formation can be inhibited by colchicine (20 μg/ml) and is, therefore, likely to be dependent directly or indirectly on microtubule function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848553
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  • 6
    Electronic Resource
    Electronic Resource
    Follicle cell development is partly independent of germ-line cell differentiation in Drosophila oogenesis (1989)
    Springer
    Development genes and evolution 198 (1989), S. 185-190 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Oogenesis ; Follicle cells ; Egg shell ; Ovarian tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The developmental potential of the cells of the somatic follicular epithelium (follicle cells) was studied in mutants in which the differentiation of the germ-line cells is blocked at different stages of oogenesis. In two mutants, sn 36a and kelch, nurse cell regression does not occur, yet the follicle cells around the small oocyte continue their normal developmental program and produce an egg shell with micropylar cone and often deformed operculum and respiratory appendages. Neither the influx of nurse cell cytoplasm into the oocyte nor the few follicle cells covering the nurse cells are apparently required for the formation of the egg shell. In the tumor mutant benign gonial cell neoplasm (bgcn) the follicle cells can also differentiate to some extent although the germ-line cells remain morphologically undifferentiated. Vitelline membrane material was synthesized by the follicle cells in some bgcn chambers and in rare cases a columnar epithelium, which resembled morphologically that of wild-type stage-9 follicles, formed around the follicle's posterior end. The normal polarity of the follicular epithelium that is characteristic for mid-vitellogenic stages may, therefore, be established in the absence of morphologically differentiating germ-line cells. However, the tumorous germ-line cells do not constitute a homogeneous cell population since in about 30% of the analyzed follicles a cell cluster at or near the posterior pole can be identified by virtue of its high number of concanavalin A binding sites. This molecular marker reveals an anteroposterior polarity of the tumorous chambers. In follicles mutant for both bgcn and the polarity gene dicephalic the cluster of concanavalin A-stained germ-line cells shifts to more anterior positions in the follicle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375904
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  • 7
    Electronic Resource
    Electronic Resource
    Expression of the zygotic genome in blastoderm stage embryos ofDrosophila: Analysis of a specific protein (1980)
    Springer
    Development genes and evolution 188 (1980), S. 153-156 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Embryogenesis ; mat (3) 1 mutation ; Two-dimensional gels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The synthesis of a protein which has been detected in blastoderm cells but not in pole cells (Gutzeit and Gehring 1979) has been studied further by means of two-dimensional gel electrophoresis. This protein could not be detected at the nuclear multiplication stage. The protein is translated from mRNA which is transcribed at the blastoderm stage since it is not synthesized in detectable amounts when embryos are injected with α-amanitin prior to the blastoderm stage. Also the protein could not be detected when RNA from freshly laid eggs was translated in vitro. Embryos from females which are homozygous for the mutationmat (3) 1 form pole cells but no blastoderm cells (Rice and Garen 1975). Thesemat (3) 1 embryos, as we will call them in this report, express the protein if aged for a period of time sufficient for completion of blastoderm cell formation in control wild-type embryos.mat (3) 1 embryos and embryos injected with α-amanitin show the same syndrome of visible developmental anomalies; however, the studied protein could only be detected inmat (3) 1 embryos but not in α-amanitin injected embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848807
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  • 8
    Electronic Resource
    Electronic Resource
    Observations on the polarity of mutant Drosophila follicles lacking the oocyte (1992)
    Springer
    Development genes and evolution 201 (1992), S. 268-274 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila oogenesis ; egalitarian ; Bicaudal-D ; Nurse-cell nuclei ; Extracellular ionic currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Homozygous females of the mutantsegalitarian andBicaudal-D R26produce follicles in which the oocyte is replaced by an additional nurse cell. Normal morphological markers for polarity can be identified in mutant follicles but the normal spatial organization of these markers is disturbed. For example, nurse-cell nuclei of different ploidy classes are present but, contrary to wild-type follicles, the nuclei show no anteroposterior ploidy gradient. The two cells with four intercellular bridges, one of which should have developed into the oocyte rather than a nurse cell, are located at the posterior pole only in young follicles (up to about stage 5), whereas during later stages they are more often found at lateral or intermediate positions. This disturbed polarity correlates with a variable aberrant pattern of extracellular ionic currents. Moreover, in the mutant follicles patches of columnar follicular epithelium differentiate locally although this type of epithelium forms normally only around the oocyte. The follicle cells at both follicle poles possess anterior quality since they migrate from both poles towards the centre of the follicle, as do the border cells restricted to the anterior pole in wild-type follicles. Our analysis indicates that in the mutants the follicular polarity is normal at first but becomes disturbed during stages 5 to 6. The secondary breakdown of polarity is likely to follow on from the absence of the oocyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592107
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  • 9
    Electronic Resource
    Electronic Resource
    Blocked endocytotic uptake by the oocyte causes accumulation of vitellogenins in the haemolymph of the female-sterile mutants quitPX61 and stand stillPS34 of Drosophila (1994)
    Springer
    Cell & tissue research 275 (1994), S. 291-298 
    Details
    ISSN: 1432-0878
    Keywords: Oogenesis ; Oocytes ; Yolk ; Haemolymph ; Vitellogenesis ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The developmental lesions in two female-sterile mutants, quit PX61 (qui) and stand still PS34 (Stil), of Drosophila have been analysed. Previtellogenic development is normal in mutant qui ovarioles but, during vitellogenic stages, only small quantities of yolk accumulate in the oocyte. The nurse-cell cytoplasm does not stream into the oocyte. However, the follicle cells continue their developmental program and synthesize an excessive quantity of eggshell material. In the mutant stil, the oocyte remains small and contains only a fraction of the yolk proteins present in wild-type follicles. Histological and ultrastructural observations and the failure to incorporate trypan blue indicate that the yolk proteins present in the mutant follicles are neither derived from the fat body nor from the follicle cells. Since, in both mutants, the uptake mechanism of vitellogenin is affected, the 3 polypeptides accumulate in the haemolymph (in stil, the protein concentration is up to 4 times higher than in wild-type females) and the haemolymph volume increases. Reciprocal transplantations of ovarioles show that the developmental lesions in both mutants are ovary-autonomous. Furthermore, genetic chimeras of stil show that the activity of the stil gene is required in the germline cells and not in the somatic tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319427
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  • 10
    Electronic Resource
    Electronic Resource
    Blocked endocytotic uptake by the oocyte causes accumulation of vitellogenins in the haemolymph of the female-sterile mutants quitPX61 and stand stillPS34 of Drosophila (1994)
    Springer
    Cell & tissue research 275 (1994), S. 291-298 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Oogenesis – Oocytes – Yolk – Haemolymph – Vitellogenesis –Drosophilamelanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The developmental lesions in two female-sterile mutants, quit PX61 (qui) and stand still PS34 (stil), of Drosophila have been analysed. Previtellogenic development is normal in mutant qui ovarioles but, during vitellogenic stages, only small quantities of yolk accumulate in the oocyte. The nurse-cell cytoplasm does not stream into the oocyte. However, the follicle cells continue their developmental program and synthesize an excessive quantity of eggshell material. In the mutant stil, the oocyte remains small and contains only a fraction of the yolk proteins present in wild-type follicles. Histological and ultrastructural observations and the failure to incorporate trypan blue indicate that the yolk proteins present in the mutant follicles are neither derived from the fat body nor from the follicle cells. Since, in both mutants, the uptake mechanism of vitellogenin is affected, the 3 polypeptides accumulate in the haemolymph (in stil, the protein concentration is up to 4 times higher than in wild-type females) and the haemolymph volume increases. Reciprocal transplantations of ovarioles show that the developmental lesions in both mutants are ovary-autonomous. Furthermore, genetic chimeras of stil show that the activity of the stil gene is required in the germ-line cells and not in the somatic tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319427
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