Drosophila virilis oskar transgenes direct body patterning but not pole cell formation or maintenance of mRNA localization in D. melanogaster

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 2027-2037 ◽  
Author(s):  
P.J. Webster ◽  
J. Suen ◽  
P.M. Macdonald
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cell ◽  
Cell Formation ◽  
Mrna Localization ◽  
Early Embryo ◽  
Posterior Pole ◽  
Early Embryogenesis ◽  
Drosophila Virilis ◽  
Pole Cell ◽  
Body Patterning

The Drosophila melanogaster gene oskar is required for both posterior body patterning and germline formation in the early embryo; precisely how oskar functions is unknown. The oskar transcript is localized to the posterior pole of the developing oocyte, and oskar mRNA and protein are maintained at the pole through early embryogenesis. The posterior maintenance of oskar mRNA is dependent upon the presence of oskar protein. We have cloned and characterized the Drosophila virilis oskar homologue, virosk, and examined its activity as a transgene in Drosophila melanogaster flies. We find that the cis-acting mRNA localization signals are conserved, although the virosk transcript also transiently accumulates at novel intermediate sites. The virosk protein, however, shows substantial differences from oskar: while virosk is able to rescue body patterning in a D. melanogaster oskar- background, it is impaired in both mRNA maintenance and pole cell formation. Furthermore, virosk induces a dominant maternal-effect lethality when introduced into a wild-type background, and interferes with the posterior maintenance of the endogenous oskar transcript in early embryogenesis. Our data suggest that virosk protein is unable to anchor at the posterior pole of the early embryo; this defect could account for all of the characteristics of virosk mentioned above. Our observations support a model in which oskar protein functions both by nucleating the factors necessary for the activation of the posterior body patterning determinant and the germ cell determinant, and by anchoring these factors to the posterior pole of the embryo. While the posterior body patterning determinant need not be correctly localized to provide body patterning activity, the germ cell determinant may need to be highly concentrated adjacent to the cortex in order to direct pole cell formation.

Oskar anchoring restricts pole plasm formation to the posterior of the Drosophila oocyte

Development ◽  
2002 ◽  
Vol 129 (15) ◽  
pp. 3705-3714 ◽  
Author(s):  
Nathalie F. Vanzo ◽  
Anne Ephrussi
Keyword(s):  
Drosophila Melanogaster ◽  
Translational Control ◽  
Cell Formation ◽  
Positional Information ◽  
Mrna Localization ◽  
Posterior Pole ◽  
Tight Coupling ◽  
Anteroposterior Patterning ◽  
Pole Cell ◽  
Pole Plasm

Localization of the maternal determinant Oskar at the posterior pole of Drosophila melanogaster oocyte provides the positional information for pole plasm formation. Spatial control of Oskar expression is achieved through the tight coupling of mRNA localization to translational control, such that only posterior-localized oskar mRNA is translated, producing the two Oskar isoforms Long Osk and Short Osk. We present evidence that this coupling is not sufficient to restrict Oskar to the posterior pole of the oocyte. We show that Long Osk anchors both oskar mRNA and Short Osk, the isoform active in pole plasm assembly, at the posterior pole. In the absence of anchoring by Long Osk, Short Osk disperses into the bulk cytoplasm during late oogenesis, impairing pole cell formation in the embryo. In addition, the pool of untethered Short Osk causes anteroposterior patterning defects, owing to the dispersion of pole plasm and its abdomen-inducing activity throughout the oocyte. We show that the N-terminal extension of Long Osk is necessary but not sufficient for posterior anchoring, arguing for multiple docking elements in Oskar. This study reveals cortical anchoring of the posterior determinant Oskar as a crucial step in pole plasm assembly and restriction, required for proper development of Drosophila melanogaster.

aubergineencodes aDrosophilapolar granule component required for pole cell formation and related to eIF2C

Development ◽  
2001 ◽  
Vol 128 (14) ◽  
pp. 2823-2832 ◽  
Author(s):  
Adam N. Harris ◽  
Paul M. Macdonald
Keyword(s):  
Polar Granule ◽  
Cell Formation ◽  
Posterior Pole ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Dependent Manner ◽  
Eukaryotic Translation ◽  
Pole Cell ◽  
Body Patterning ◽  
Pole Plasm

In Drosophila oocytes, activation of Oskar translation from a transcript localized to the posterior pole is an essential step in the organization of the pole plasm, specialized cytoplasm that contains germline and abdominal body patterning determinants. Oskar is a component of polar granules, large particles associated with the pole plasm and the germline precursor pole cells of the embryo. aubergine mutants fail to translate oskar mRNA efficiently and are thus defective in posterior body patterning and pole cell formation. We have found that Aubergine protein is related to eukaryotic translation initiation factor 2C and suggest how it may activate translation. In addition, we found that Aubergine was recruited to the posterior pole in a vas-dependent manner and is itself a polar granule component. Consistent with its presence in these structures, Aubergine is required for pole cell formation independently of its initial role in oskar translation. Unlike two other known polar granule components, Vasa and Oskar, Aubergine remains cytoplasmic after pole cell formation, suggesting that the roles of these proteins diverge during embryogenesis.

scholarly journals Receptor-mediated yolk uptake is required for oskar mRNA localization and cortical anchorage of germ plasm components in the Drosophila oocyte

PLoS Biology ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. e3001183
Author(s):  
Tsubasa Tanaka ◽  
Naoki Tani ◽  
Akira Nakamura
Keyword(s):  
Germ Cell ◽  
Germ Plasm ◽  
Cell Formation ◽  
Mrna Localization ◽  
Posterior Pole ◽  
Actin Remodeling ◽  
Yolk Proteins ◽  
Anterior Dorsal ◽  
Cortical Anchorage ◽  
Germ Cell Formation

TheDrosophilagerm plasm is responsible for germ cell formation. Its assembly begins with localization ofoskarmRNA to the posterior pole of the oocyte. Theoskartranslation produces 2 isoforms with distinct functions: short Oskar recruits germ plasm components, whereas long Oskar remodels actin to anchor the components to the cortex. The mechanism by which long Oskar anchors them remains elusive. Here, we report that Yolkless, which facilitates uptake of nutrient yolk proteins into the oocyte, is a key cofactor for long Oskar. Loss of Yolkless or depletion of yolk proteins disrupts the microtubule alignment andoskarmRNA localization at the posterior pole of the oocyte, whereas microtubule-dependent localization ofbicoidmRNA to the anterior andgurkenmRNA to the anterior-dorsal corner remains intact. Furthermore, these mutant oocytes do not properly respond to long Oskar, causing defects in the actin remodeling and germ plasm anchoring. Thus, the yolk uptake is not merely the process for nutrient incorporation, but also crucial foroskarmRNA localization and cortical anchorage of germ plasm components in the oocyte.

Mutations in a newly identified Drosophila melanogaster gene, mago nashi, disrupt germ cell formation and result in the formation of mirror-image symmetrical double abdomen embryos

Development ◽  
1991 ◽  
Vol 113 (1) ◽  
pp. 373-384 ◽  
Author(s):  
R.E. Boswell ◽  
M.E. Prout ◽  
J.C. Steichen
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cell ◽  
Cell Formation ◽  
Temperature Shift ◽  
Longitudinal Axis ◽  
Posterior Pole ◽  
Mirror Image ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Mago Nashi

The mago nashi (mago) locus is a newly identified strict maternal effect, grandchildless-like, gene in Drosophila melanogaster. In homozygous mutant mago females reared at 17 degrees C, mago+ function is reduced, the inviable embryos lack abdominal segments and 84–98% of the embryos die. In contrast, at 25 degrees C, some mago alleles produce a novel gene product capable of inducing the formation of symmetrical double abdomen embryos. Reciprocal temperature-shift experiments indicate that the temperature-sensitive period is during oogenetic stages 7–14. Furthermore, embryos collected from mago1 homozygous females contain no apparent functional posterior determinants in the posterior pole. In viable F1 progeny from mago mutant females, regardless of genotype and temperature, polar granules are reduced or absent and germ cells fail to form (the grandchildless-like phenotype). Thus, we propose that the mago+ product is a component of the posterior determinative system, required during oogenesis, both for germ cell determination and delineation of the longitudinal axis of the embryo.

Differentiation and positioning of nuclei in eggs of the cecidomyid Heteropeza pygmaea

1976 ◽  
Vol 22 (1) ◽  
pp. 99-113
Author(s):  
M. Meats ◽  
J.B. Tucker
Keyword(s):  
Structural Changes ◽  
Early Stage ◽  
Cell Formation ◽  
Longitudinal Axis ◽  
Posterior Pole ◽  
Spindle Orientation ◽  
Specific Sequence ◽  
Pole Cell ◽  
Polar Granules ◽  
Egg Chamber

During the first three cleavage divisions of the egg nuclei a precise sequence of spindle orientation and elongation parallel to the longitudinal axis of the egg is apparently involved in positioning one nucleus among the polar granules at the posterior pole of the egg. The size of this nucleus, and the position at which the egg cleaves when pole cell formation occurs, appear to constitute part of the mechanism which ensures that only one nucleus is included in the first pole cell. Blastoderm formation occurs without a well-defined migration of nuclei to the egg surface. Nuclei are so large in relation to the size of the egg that uniform spacing and distribution of nuclei ensures that a large proportion are situated near the egg surface. Those nuclei which are near the egg surface divide synchronously to form a layer of blastoderm nuclei, while membranous cleavage furrows invaginate from the egg surface between them. Nuclei in the central region of the egg chamber condense to form yolk nuclei before blastoderm nuclei have been separated from the rest of the egg by the completion of the cleavage membranes. Polar granules provide the only evidence of fine-structural differences in different regions of the egg chamber cytoplasm. They are found near the posterior pole of the egg from an early stage of oogenesis. They undergo a specific sequence of structural changes and increase in size as the egg grows. No microtubular or microfibrillar arrays have been found in the egg chamber which might form a cytoskeletal basis for spindle orientation or for the spatial differences which develop during differentiation of the uncleaved egg cytoplasm.

Role for mRNA localization in translational activation but not spatial restriction of nanos RNA

Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 659-669 ◽  
Author(s):  
S.E. Bergsten ◽  
E.R. Gavis
Keyword(s):  
Translational Control ◽  
Rna Localization ◽  
Early Embryo ◽  
Posterior Pole ◽  
Translational Repression ◽  
Control Element ◽  
Regulatory Sequences ◽  
Cis Acting ◽  
Body Patterning ◽  
Localization Signal

Patterning of the anterior-posterior body axis during Drosophila development depends on the restriction of Nanos protein to the posterior of the early embryo. Synthesis of Nanos occurs only when maternally provided nanos RNA is localized to the posterior pole by a large, cis-acting signal in the nanos 3′ untranslated region (3′UTR); translation of unlocalized nanos RNA is repressed by a 90 nucleotide Translational Control Element (TCE), also in the 3′UTR. We now show quantitatively that the majority of nanos RNA in the embryo is not localized to the posterior pole but is distributed throughout the cytoplasm, indicating that translational repression is the primary mechanism for restricting production of Nanos protein to the posterior. Through an analysis of transgenes bearing multiple copies of nanos 3′UTR regulatory sequences, we provide evidence that localization of nanos RNA by components of the posteriorly localized germ plasm activates its translation by preventing interaction of nanos RNA with translational repressors. This mutually exclusive relationship between translational repression and RNA localization is mediated by a 180 nucleotide region of the nanos localization signal, containing the TCE. These studies suggest that the ability of RNA localization to direct wild-type body patterning also requires recognition of multiple, unique elements within the nanos localization signal by novel factors. Finally, we propose that differences in the efficiencies with which different RNAs are localized result from the use of temporally distinct localization pathways during oogenesis.

The casein kinase 1 alpha gene of Drosophila melanogaster is developmentally regulated and the kinase activity of the protein induced by DNA damage

1996 ◽  
Vol 109 (7) ◽  
pp. 1847-1856 ◽  
Author(s):  
J.A. Santos ◽  
E. Logarinho ◽  
C. Tapia ◽  
C.C. Allende ◽  
J.E. Allende ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Kinase Activity ◽  
Early Embryo ◽  
Casein Kinase ◽  
Early Embryogenesis ◽  
Kinase Gene ◽  
Casein Kinase 1 ◽  
Adult Females ◽  
Early Embryos

We report the molecular cloning and characterisation of the first CK1(casein kinase) gene of Drosophila melanogaster (dmCK1). The protein sequence (DMCK1) shares significant homology with other mammalian CK1 protein kinases of the alpha sub-class. The dmCK1 gene is expressed only in adult females and during early embryonic development as a single transcript. Western blot analysis of total protein extracts of different stages of development show that the gene product is likewise present during early embryogenesis and in adult females. Kinase activity studies show that DMCK1 is active when in vitro translated but inactive when immunoprecipitated from total early embryo extracts. However, after dephosphorylation treatment the immunoprecipitates show high kinase activity. More significantly, DMCK1 kinase activity present in the immunoprecipitates can be specifically activated by gamma-irradiation of early embryos. Also, when DMCK1 is immunoprecipitated after irradiation it appears to undergo phosphorylation. Immunolocalization of DMCK1 in early embryos shows that the protein is predominantly cytoplasmic but after irradiation there is a significant relocalization to the interphase nucleus. The results suggest a possible requirement of the Drosophila CK1 alpha for mechanisms associated with DNA repair during early embryogenesis.

l(3)malignant brain tumor and Three Novel Genes Are Required for Drosophila Germ-Cell Formation

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 1889-1900 ◽  
Author(s):  
Christopher B Yohn ◽  
Leslie Pusateri ◽  
Vitor Barbosa ◽  
Ruth Lehmann
Keyword(s):  
Brain Tumor ◽  
Germ Cell ◽  
Germ Plasm ◽  
Nuclear Division ◽  
Cell Formation ◽  
Nuclear Migration ◽  
Early Embryo ◽  
Malignant Brain Tumor ◽  
Mitotic Synchrony ◽  
Germ Cell Formation

Abstract To identify genes involved in the process of germ-cell formation in Drosophila, a maternal-effect screen using the FLP/FRT-ovoD method was performed on chromosome 3R. In addition to expected mutations in the germ-cell determinant oskar and in other genes known to be involved in the process, several novel mutations caused defects in germ-cell formation. Mutations in any of three genes [l(3)malignant brain tumor, shackleton, and out of sync] affect the synchronous mitotic divisions and nuclear migration of the early embryo. The defects in nuclear migration or mitotic synchrony result in a reduction in germ-cell formation. Mutations in another gene identified in this screen, bebra, do not cause mitotic defects, but appear to act upstream of the localization of oskar. Analysis of our mutants demonstrates that two unique and independent processes must occur to form germ cells—germ-plasm formation and nuclear division/migration.

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