The maternal gene nanos has a central role in posterior pattern formation of the Drosophila embryo

Development ◽  
1991 ◽  
Vol 112 (3) ◽  
pp. 679-691 ◽  
Author(s):  
R. Lehmann ◽  
C. Nusslein-Volhard
Keyword(s):  
Germ Line ◽  
Physical Structure ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Posterior Group ◽  
Dependent Activity ◽  
Functional Pathway ◽  
Pole Plasm ◽  
Maternal Gene ◽  
Cytoplasmic Transfer

A group of maternal genes, the posterior group, is required for the development of the abdominal region in the Drosophila embryo. We have used genetic as well as cytoplasmic transfer experiments to order seven of the posterior group genes (nanos, pumilio, oskar, valois, vasa, staufen and tudor) into a functional pathway. An activity present in the posterior pole plasm of wild-type embryos can restore normal abdominal development in posterior group mutants. This activity is synthesized during oogenesis and the gene nanos most likely encodes this activity. The other posterior group genes have distinct accessory functions: pumilio acts downstream of nanos and is required for the distribution or stability of the nanos-dependent activity in the embryo. Staufen, oskar, vasa, valois and tudor act upstream of nanos. Embryos from females mutant for these genes lack the specialized posterior pole plasm and consequently fail to form germ-cell precursors. We suggest that the products of these genes provide the physical structure necessary for the localization of nanos-dependent activity and of germ line determinants.

Segmental polarity and identity in the abdomen of Drosophila is controlled by the relative position of gap gene expression

Development ◽  
1989 ◽  
Vol 107 (Supplement) ◽  
pp. 21-29 ◽  
Author(s):  
Ruth Lehmann ◽  
Hans Georg Frohnhöfer
Keyword(s):  
Gene Expression ◽  
Relative Concentration ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Gene Products ◽  
Gap Gene ◽  
Gap Genes ◽  
Posterior Group ◽  
Pole Plasm ◽  
Maternal Gene

The establishment of the segmental pattern in the Drosophila embryo is directed by three sets of maternal genes: the anterior, the terminal and the posterior group of genes. Embryos derived from females mutant for one of the posterior group genes lack abdominal segmentation. This phenotype can be rescued by transplantation of posterior pole plasm into the abdominal region of mutant embryos. We transplanted posterior pole plasm into the middle of embryos mutant either for the posterior, the anterior and posterior, or all three maternal systems and monitored the segmentation pattern as well as the expression of the zygotic gap gene Krüppel in control and injected embryos. We conclude that polarity and identity of the abdominal segments do not depend on the relative concentration of posterior activity but rather on the position of gap gene expression. By changing the pattern of gap gene expression, the orientation of the abdomen can be reversed. These experiments suggest that maternal gene products act in a strictly hierarchical manner. The function of the maternal gene products becomes dispensable once the position of the zygotically expressed gap genes is determined. Subsequently the gap genes will control the pattern of the pair-rule and segment polarity genes.

scholarly journals The actin cytoskeleton is required for maintenance of posterior pole plasm components in the Drosophila embryo

1999 ◽  
Vol 85 (1-2) ◽  
pp. 111-122 ◽  
Author(s):  
Valerie A Lantz ◽  
Scott E Clemens ◽  
Kathryn G Miller
Keyword(s):  
Actin Cytoskeleton ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Pole Plasm

Mutations in the Drosophila gene bullwinkle cause the formation of abnormal eggshell structures and bicaudal embryos

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3023-3033 ◽  
Author(s):  
K.R. Rittenhouse ◽  
C.A. Berg
Keyword(s):  
Cell Migration ◽  
Cell Fate ◽  
Germ Line ◽  
Follicle Cell ◽  
Posterior Pole ◽  
Mirror Image ◽  
Follicle Cells ◽  
Anterior Pole ◽  
Posterior Group ◽  
General Transport

Subcellular localization of gene products and cell migration are both critical for pattern formation during development. The bullwinkle gene is required in Drosophila for disparate aspects of these processes. In females mutant at the bullwinkle locus, the follicle cells that synthesize the dorsal eggshell filaments do not migrate properly, creating short, broad structures. Mosaic analyses demonstrate that wild-type BULLWINKLE function is required in the germ line for these migrations. Since the mRNA for gurken, the putative ligand that signals dorsal follicle cell fate, is correctly localized in bullwinkle mutants, we conclude that our bullwinkle alleles do not affect the dorsoventral polarity of the oocyte and thus must be affecting the follicle cell migrations in some other way. In addition, the embryos that develop from bullwinkle mothers are bicaudal. A KINESIN:beta-GALACTOSIDASE fusion protein is correctly localized to the posterior pole of bullwinkle oocytes during stage 9. Thus, the microtubule structure of the oocyte and general transport along it do not appear to be disrupted prior to cytoplasmic streaming. Unlike other bicaudal mutants, oskar mRNA is localized correctly to the posterior pole of the oocyte at stage 10. By early embryogenesis, however, some oskar mRNA is mislocalized to the anterior pole. Consistent with the mislocalization of oskar mRNA, a fraction of the VASA protein and nanos mRNA are also mislocalized to the anterior pole of bullwinkle embryos. Mislocalization of nanos mRNA to the anterior is dependent on functional VASA protein. Although the mirror-image segmentation defects appear to result from the action of the posterior group genes, germ cells are not formed at the anterior pole. The bicaudal phenotype is also germ-line dependent for bullwinkle. We suspect that BULLWINKLE interacts with the cytoskeleton and extracellular matrix and is necessary for gene product localization and cell migration during oogenesis after stage 10a.

scholarly journals mago nashi mediates the posterior follicle cell-to-oocyte signal to organize axis formation in Drosophila

Development ◽  
1997 ◽  
Vol 124 (16) ◽  
pp. 3197-3207 ◽  
Author(s):  
P.A. Newmark ◽  
S.E. Mohr ◽  
L. Gong ◽  
R.E. Boswell
Keyword(s):  
Germ Plasm ◽  
Egf Receptor ◽  
Germ Line ◽  
Follicle Cell ◽  
Posterior Pole ◽  
Follicle Cells ◽  
Oocyte Nucleus ◽  
Axis Formation ◽  
Pole Plasm ◽  
Mago Nashi

Establishment of the anteroposterior and dorsoventral axes in the Drosophila egg chamber requires reciprocal signaling between the germ line and soma. Upon activation of the Drosophila EGF receptor in the posterior follicle cells, these cells signal back to the oocyte, resulting in a reorganization of the oocyte cytoplasm and anterodorsal migration of the oocyte nucleus. We demonstrate that the gene mago nashi (mago) encodes an evolutionarily conserved protein that must be localized within the posterior pole plasm for germ-plasm assembly and Caenorhabditis elegans mago is a functional homologue of Drosophila mago. In the absence of mago+ function during oogenesis, the anteroposterior and dorsoventral coordinates of the oocyte are not specified and the germ plasm fails to assemble.

Probing Drosophila gene function by antisense RNA

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 422-425 ◽  
Author(s):  
Reinhard Schuh ◽  
Herbert Jäckle
Keyword(s):  
Antisense Rna ◽  
Germ Line ◽  
Conventional Technique ◽  
Transcription Unit ◽  
The Body ◽  
Mutant Phenotype ◽  
Drosophila Embryo ◽  
Alternative Approach ◽  
Pattern Forming ◽  
Germ Line Transformation

The conventional technique for assigning a particular genetic function to a cloned transcription unit has relied on the rescue of the mutant phenotype by germ line transformation. An alternative approach is to mimic a mutant phenotype by the use of antisense RNA injections to produce phenocopies. This approach has been successfully used to identify genes involved in early pattern forming processes in the Drosophila embryo. At the time when antisense RNA is injected, the embryo develops as a syncytium composed of about 5000 nuclei which share a common cytoplasm. The gene interactions required to establish the body plan occur before cellularization at the blastoderm stage. Thus the nuclei and their exported transcripts are accessible to the injected antisense RNA. The antisense RNA interferes with the endogenous RNA by an as yet unidentified mechanism. The extent of interference is only partial and produces phenocopies with characteristics of weak mutant alleles. In our lab and others, this approach has been successfully used to identify several genes required for normal Drosophila pattern formation.Key words: Drosophila segmentation, phenocopy, antisense RNA, Krüppel gene.

Development of the germ cells and reproductive primordia in male and female embryos of Rhodnius prolixus Stål (Hemiptera: Reduviidae)

1994 ◽  
Vol 72 (6) ◽  
pp. 1100-1119 ◽  
Author(s):  
B. S. Heming ◽  
E. Huebner
Keyword(s):  
Germ Cells ◽  
Dorsal Surface ◽  
Interstitial Cells ◽  
Rhodnius Prolixus ◽  
Posterior Pole ◽  
Male And Female ◽  
Functional Aspects ◽  
Pole Plasm ◽  
Blastodermal Cells ◽  
Sheath Cells

Newly deposited eggs of Rhodnius prolixus lack a visible pole plasm and require 14 days to develop at 27 °C and 70% RH. The first germ cells originate at 9% of embryogenesis by asynchronous mitosis of blastodermal cells behind the germ Anlage at the posterior pole of the egg. From 9 to 17%, these proliferate to a mean of 270 cells and, from 13 to 18%, migrate forward over the dorsal surface of the mesoderm and lodge in abdominal segments 3–7. Between 22 and 30%, they shift laterally and segregate into three or four paired clumps between segments 3 and 4, 4 and 5, 5 and 6, and, sometimes, 6 and 7 and, from 30 to 37%, gradually assemble into a continuous longitudinal mass on either side of segments 3–6, where they begin to associate with mesodermal cells. Between 37 and 46%, these collect between (males) and around the germ cells to form the rudiments of the terminal filaments (females), inner and outer gonadal sheaths, interstitial cells (males), and primary exit ducts. Dorsally situated sheath cells then invaginate ventrally into each gonadal rudiment, partitioning it into seven compartments, each containing a mean of 15 oogonia or 16 spermatogonia. These seem to fuse into a rosette, at least in females, but do not begin to divide again until after hatch. Excluded germ cells lodge within the rudiments of one or both exit ducts. The evolutionary and functional aspects of our findings are addressed and new observations are presented on the mechanism of anatrepsis.

scholarly journals Identification of a component of Drosophila polar granules

Development ◽  
1988 ◽  
Vol 103 (4) ◽  
pp. 625-640 ◽  
Author(s):  
B. Hay ◽  
L. Ackerman ◽  
S. Barbel ◽  
L.Y. Jan ◽  
Y.N. Jan
Keyword(s):  
Germ Line ◽  
Posterior Pole ◽  
Nuclear Bodies ◽  
Maternal Origin ◽  
Pole Cell ◽  
Polar Granules ◽  
Early Embryos ◽  
Biochemical Studies ◽  
Males And Females ◽  
Pole Cells

Information necessary for the formation of pole cells, precursors of the germ line, is provided maternally and localized to the posterior pole of the Drosophila egg. The maternal origin and posterior localization of polar granules suggest that they may be associated with pole cell determinants. We have generated an antibody (Mab46F11) against polar granules. In oocytes and early embryos, the Mab46F11 antigen is sharply localized to the posterior embryonic pole. In pole cells, it becomes associated with nuclear bodies within, and nuage around, the nucleus. Immunoreactivity remains associated with cells of the germ line throughout the life cycle of both males and females. This antibody recognizes a 72–74 × 10(3) Mr protein and is useful both as a pole lineage marker and in biochemical studies of polar granules.

scholarly journals Circumventing Zygotic Lethality to Generate Maternal Mutants in Zebrafish

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 102
Author(s):  
De-Li Shi
Keyword(s):  
Germ Line ◽  
Gene Products ◽  
Transgenic Expression ◽  
Guide Rna ◽  
Guide Rnas ◽  
Transgenic Embryos ◽  
Mutant Phenotypes ◽  
Biallelic Mutations ◽  
Genome Activation ◽  
Maternal Gene

Maternal gene products accumulated during oogenesis are essential for supporting early developmental processes in both invertebrates and vertebrates. Therefore, understanding their regulatory functions should provide insights into the maternal control of embryogenesis. The CRISPR/Cas9 genome editing technology has provided a powerful tool for creating genetic mutations to study gene functions and developing disease models to identify new therapeutics. However, many maternal genes are also essential after zygotic genome activation; as a result, loss of their zygotic functions often leads to lethality or sterility, thus preventing the generation of maternal mutants by classical crossing between zygotic homozygous mutant adult animals. Although several approaches, such as the rescue of mutant phenotypes through an injection of the wild-type mRNA, germ-line replacement, and the generation of genetically mosaic females, have been developed to overcome this difficulty, they are often technically challenging and time-consuming or inappropriate for many genes that are essential for late developmental events or for germ-line formation. Recently, a method based on the oocyte transgenic expression of CRISPR/Cas9 and guide RNAs has been designed to eliminate maternal gene products in zebrafish. This approach introduces several tandem guide RNA expression cassettes and a GFP reporter into transgenic embryos expressing Cas9 to create biallelic mutations and inactivate genes of interest specifically in the developing oocytes. It is particularly accessible and allows for the elimination of maternal gene products in one fish generation. By further improving its efficiency, this method can be used for the systematic characterization of maternal-effect genes.

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.

The differentiation of the posterior pole-plasm in the housefly Musca vicina macquart

1959 ◽  
Vol 16 (2) ◽  
pp. 427-429 ◽  
Author(s):  
N.I. Bhuiyan ◽  
S.A. Shafiq
Keyword(s):  
Posterior Pole ◽  
Pole Plasm
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