maelstrom is required for an early step in the establishment of Drosophila oocyte polarity: posterior localization of grk mRNA

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4661-4671 ◽  
Author(s):  
N.J. Clegg ◽  
D.M. Frost ◽  
M.K. Larkin ◽  
L. Subrahmanyan ◽  
Z. Bryant ◽  
...  
Keyword(s):  
Nurse Cell ◽  
Egf Receptor ◽  
Mrna Localization ◽  
Follicle Cells ◽  
Rna Transport ◽  
Nurse Cells ◽  
Loss Of Function ◽  
Cell Fates ◽  
Early Step ◽  
Novel Protein

We describe a mutant, maelstrom, that disrupts a previously unobserved step in mRNA localization within the early oocyte, distinct from nurse-cell-to-oocyte RNA transport. Mutations in maelstrom disturb the localization of mRNAs for Gurken (a ligand for the Drosophila Egf receptor), Oskar and Bicoid at the posterior of the developing (stage 3–6) oocyte. maelstrom mutants display phenotypes detected in gurken loss-of-function mutants: posterior follicle cells with anterior cell fates, bicoid mRNA localization at both poles of the stage 8 oocyte and ventralization of the eggshell. These data are consistent with the suggestion that early posterior localization of gurken mRNA is essential for activation of the Egf receptor pathway in posterior follicle cells. Posterior localization of mRNA in stage 3–6 oocytes could therefore be one of the earliest known steps in the establishment of oocyte polarity. The maelstrom gene encodes a novel protein that has a punctate distribution in the cytoplasm of the nurse cells and the oocyte until the protein disappears in stage 7 of oogenesis.

The neurogenic locus brainiac cooperates with the Drosophila EGF receptor to establish the ovarian follicle and to determine its dorsal-ventral polarity

Development ◽  
1992 ◽  
Vol 116 (1) ◽  
pp. 177-192 ◽  
Author(s):  
S. Goode ◽  
D. Wright ◽  
A.P. Mahowald
Keyword(s):  
Nurse Cell ◽  
Egf Receptor ◽  
Ovarian Follicle ◽  
Follicle Cell ◽  
Cell Complex ◽  
Follicle Cells ◽  
Sensitive Period ◽  
Cell Fates ◽  
Genetic Mosaic

We have characterized the function of a new neurogenic locus, brainiac (brn), during oogenesis. Homozygous brn females lay eggs with fused dorsal appendages, a phenotype associated with torpedo (top) alleles of the Drosophila EGF receptor (DER) locus. By constructing double mutant females for both brn and top, we have found that brn is required for determining the dorsal-ventral polarity of the ovarian follicle. However, embryos from mature brn eggs develop a neurogenic phenotype which can be zygotically rescued if a wild-type sperm fertilizes the egg. This is the first instance of a Drosophila gene required for determination of dorsal-ventral follicle cell fates that is not required for determination of embryonic dorsal-ventral cell fates. The temperature-sensitive period for brn dorsal-ventral patterning begins at the inception of vitellogenesis. The interaction between brn and DER is also required for at least two earlier follicle cell activities which are necessary to establish the ovarian follicle. Prefollicular cells fail to migrate between each oocyte/nurse cell complex, resulting in follicles with multiple sets of oocytes and nurse cells. brn and DER function is also required for establishing and/or maintaining a continuous follicular epithelium around each oocyte/nurse cell complex. These brn functions as well as the brn requirement for determination of dorsal-ventral polarity appear to be genetically separable functions of the brn locus. Genetic mosaic experiments show that brn is required in the germline during these processes whereas the DER is required in the follicle cells. We propose that brn may be part of a germline signaling pathway differentially regulating successive DER-dependent follicle cell activities of migration, division and/or adhesion and determination during oogenesis. These experiments indicate that brn is required in both tyrosine kinase and neurogenic intercellular signaling pathways. Moreover, the functions of brn in oogenesis are distinct from those of Notch and Delta, two other neurogenic loci that are known to be required for follicular development.

Sequential activation of the EGF receptor pathway during Drosophila oogenesis establishes the dorsoventral axis

Development ◽  
1998 ◽  
Vol 125 (2) ◽  
pp. 191-200 ◽  
Author(s):  
A. Sapir ◽  
R. Schweitzer ◽  
B.Z. Shilo
Keyword(s):  
Target Genes ◽  
Egf Receptor ◽  
Ectopic Expression ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Cell Fates ◽  
Dorsoventral Axis ◽  
Spatial Coordinates ◽  
Sequential Activation

Previous work has demonstrated a role for the Drosophila EGF receptor (Torpedo/DER) and its ligand, Gurken, in the determination of anterioposterior and dorsoventral axes of the follicle cells and oocyte. The roles of DER in establishing the polarity of the follicle cells were examined further, by following the expression of DER-target genes. One class of genes (e.g. kekon) is induced by the DER pathway at all stages. Broad expression of kekon at the stage in which the follicle cells migrate posteriorly over the oocyte, demonstrates the capacity of the pathway to pattern all follicle cells except the ventral-most rows. This may provide the spatial coordinates for the ventral-most follicle cell fates. A second group of target genes (e.g. rhomboid (rho)) is induced only at later stages of oogenesis, and may require additional inputs by signals emanating from the anterior, stretch follicle cells. The function of Rho was analyzed by ectopic expression in the stretch follicle cells, and shown to induce a non-autonomous dorsalizing activity that is independent of Gurken. Rho thus appears to be involved in processing a DER ligand in the follicle cells, to pattern the egg chamber and allow persistent activation of the DER pathway during formation of the dorsal appendages.

scholarly journals Vps13 is required for timely removal of nurse cell corpses

Development ◽  
2020 ◽  
Vol 147 (20) ◽  
pp. dev191759
Author(s):  
Anita I. E. Faber ◽  
Marianne van der Zwaag ◽  
Hein Schepers ◽  
Ellie Eggens-Meijer ◽  
Bart Kanon ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Programmed Cell Death ◽  
Nurse Cell ◽  
Close Association ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Lipid Transfer ◽  
Membranous Structure ◽  
Membrane Contact Sites

ABSTRACTProgrammed cell death and consecutive removal of cellular remnants is essential for development. During late stages of Drosophila melanogaster oogenesis, the small somatic follicle cells that surround the large nurse cells promote non-apoptotic nurse cell death, subsequently engulf them, and contribute to the timely removal of nurse cell corpses. Here, we identify a role for Vps13 in the timely removal of nurse cell corpses downstream of developmental programmed cell death. Vps13 is an evolutionarily conserved peripheral membrane protein associated with membrane contact sites and lipid transfer. It is expressed in late nurse cells, and persistent nurse cell remnants are observed when Vps13 is depleted from nurse cells but not from follicle cells. Microscopic analysis revealed enrichment of Vps13 in close proximity to the plasma membrane and the endoplasmic reticulum in nurse cells undergoing degradation. Ultrastructural analysis uncovered the presence of an underlying Vps13-dependent membranous structure in close association with the plasma membrane. The newly identified structure and function suggests the presence of a Vps13-dependent process required for complete degradation of bulky remnants of dying cells.

Drosophila-Raf Acts to Elaborate Dorsoventral Pattern in the Ectoderm of Developing Embryos

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1031-1044
Author(s):  
Kori Radke ◽  
Kimberly Johnson ◽  
Rong Guo ◽  
Anne Davidson ◽  
Linda Ambrosio
Keyword(s):  
Egf Receptor ◽  
Drosophila Embryo ◽  
Functional Requirements ◽  
Loss Of Function ◽  
Maternal Role ◽  
Partial Loss ◽  
Cell Fates ◽  
Regulatory Domains ◽  
Early Drosophila Embryo ◽  
Lateral Cell

Abstract In the early Drosophila embryo the activity of the EGF-receptor (Egfr) is required to instruct cells to adopt a ventral neuroectodermal fate. Using a gain-of-function mutation we showed that D-raf acts to transmit this and other late-acting embryonic Egfr signals. A novel role for D-raf was also identified in lateral cell development using partial loss-of-function D-raf mutations. Thus, we provide evidence that zygotic D-raf acts to specify cell fates in two distinct pathways that generate dorsoventral pattern within the ectoderm. These functional requirements for D-raf activity occur subsequent to its maternal role in organizing the anterioposterior axis. The consequences of eliminating key D-raf regulatory domains and specific serine residues in the transmission of Egfr and lateral epidermal signals were also addressed here.

Drosophila rhino Encodes a Female-Specific Chromo-domain Protein That Affects Chromosome Structure and Egg Polarity

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1117-1134 ◽  
Author(s):  
Alison M Volpe ◽  
Heidi Horowitz ◽  
Constance M Grafer ◽  
Stephen M Jackson ◽  
Celeste A Berg
Keyword(s):  
Nurse Cell ◽  
Chromosome Structure ◽  
Nurse Cells ◽  
Embryonic Patterning ◽  
Loss Of Function ◽  
Cell Nuclei ◽  
Heterochromatin Protein 1 ◽  
Chromo Domain ◽  
Egg Chambers ◽  
Female Specific

Abstract Here we describe our analyses of Rhino, a novel member of the Heterochromatin Protein 1(HP1) subfamily of chromo box proteins. rhino (rhi) is expressed only in females and chiefly in the germline, thus providing a new tool to dissect the role of chromo-domain proteins in development. Mutations in rhi disrupt eggshell and embryonic patterning and arrest nurse cell nuclei during a stage-specific reorganization of their polyploid chromosomes, a mitotic-like state called the “five-blob” stage. These visible alterations in chromosome structure do not affect polarity by altering transcription of key patterning genes. Expression levels of gurken (grk), oskar (osk), bicoid (bcd), and decapentaplegic (dpp) transcripts are normal, with a slight delay in the appearance of bcd and dpp mRNAs. Mislocalization of grk and osk transcripts, however, suggests a defect in the microtubule reorganization that occurs during the middle stages of oogenesis and determines axial polarity. This defect likely results from aberrant Grk/Egfr signaling at earlier stages, since rhi mutations delay synthesis of Grk protein in germaria and early egg chambers. In addition, Grk protein accumulates in large, actin-caged vesicles near the endoplasmic reticulum of stages 6–10 egg chambers. We propose two hypotheses to explain these results. First, Rhi may play dual roles in oogenesis, independently regulating chromosome compaction in nurse cells at the end of the unique endoreplication cycle 5 and repressing transcription of genes that inhibit Grk synthesis. Thus, loss-of-function mutations arrest nurse cell chromosome reorganization at the five-blob stage and delay production or processing of Grk protein, leading to axial patterning defects. Second, Rhi may regulate chromosome compaction in both nurse cells and oocyte. Loss-of-function mutations block nurse cell nuclear transitions at the five-blob stage and activate checkpoint controls in the oocyte that arrest Grk synthesis and/or inhibit cytoskeletal functions. These functions may involve direct binding of Rhi to chromosomes or may involve indirect effects on pathways controlling these processes.

Localisation of potassium pumps in Drosophila ovarian follicles

Zygote ◽  
1994 ◽  
Vol 2 (3) ◽  
pp. 189-200 ◽  
Author(s):  
Johannes Bohrmann ◽  
Ulf-Rüdiger Heinrich
Keyword(s):  
Nurse Cell ◽  
Cell Membranes ◽  
Plasma Membranes ◽  
Ionic Current ◽  
Ovarian Follicles ◽  
Follicle Cells ◽  
Potassium Ions ◽  
Nurse Cells ◽  
Strong Activity ◽  
Development Processes

SummaryIt has been shown previously that, in Drosophila oogenesis, potassium ions are important for bioelectric phenomena as well as for other physiological and development processes. In the present study we determined the spatial distribution and activity of the (Na+, K+)-pump and of ouabain-insensitive K+ pumps in plasma membranes of vitellogenic ovarian follicles (stage 10). We used that light micorscopic anthroylouabain method as well as the cytochemical lead and cerium precipitation methods in combination with electron spectroscopic imaging (ESI) and elelctronm energy-loss spectroscopy (EELS). (Na+, K+)-ATPase activity was predominantly observed on the oolemma as well as on the membranes of the columnar follicle cells covering the oocyte, whereas on the membranes of the nurse cells and of the squamous follicle cells covering the nurse cells the activity was vary low. The highset activity of the (Na+ K+)-pump was found at the anterior and posterior ends of the oocute, and this on the oolemma as well as on the membranes of the follicle cells located here. Strong activity of ouabain-insensitive K+-pumps was observed on most of the oolemma (except at the anterior of the oocyte) and on the membranes of some nurse cells located next to the oocyte, whereas less activity was found on the other nurse cell membranes and on the membranes of all follicle cells. The suitability of the differnet methods nurse cell membranes and on the membrances of all follicle cells. The suitability of th different methods used for determining the localisation as well as the activity of K+-pumps is discussed. We further discuss the nature of the ouabain-insensitive K+ pumps and the relevance of the observed distribution of K+-pumps for K+ uptake, extrafollicular ionic current flow intercelluar signalling and other developmental processes in Drosophila oogenesis.

Memoirs: Certain Phenomena of Tenthredinid Oogenesis as Revealed Mainly by Feulgen's Nuclear-Reaction

1930 ◽  
Vol s2-73 (292) ◽  
pp. 617-630
Author(s):  
R.A. R. GRESSON
Keyword(s):  
Nurse Cell ◽  
Chemical Change ◽  
Follicle Cell ◽  
Nuclear Material ◽  
Methyl Blue ◽  
Follicle Cells ◽  
Nuclear Chromatin ◽  
Nurse Cells ◽  
Cell Nuclei ◽  
Nucleolar Material

1. By the use of Feulgen's ‘nuclealreaktion’ certain points of Tenthredinid oogenesis have been subjected to closer study. The chromatin of the early nurse-cells of Allantus pallipes exists in the form of granules, the majority of which occur close to the nuclear membrane. In the older cells a nuclear network appears in which is distributed granules of chromatin. In Thrinax mixta, where the ovarioles were more highly developed, the chromatin of the nurse-cells occurs as granules scattered through the nucleus; a nuclear network is not present, but certain granules appear to be connected by a thread. The granules which were shown to surround the nurse-cell nuclei (in material treated by Bensley's method and also by fixation in Bouin's picro-formol and subsequently stained in iron haematoxylin) and which were formerly regarded as chromatin emissions from the nurse-cell nuclei (9) were not revealed by Feulgen's technique. They therefore cannot be regarded as chromatin. Their precise nature and origin remains undetermined. 2. The nucleoli of the early nurse-cells of both species, as revealed by Mann's methyl-blue eosin, are faintly basophil. Later they break up into a number of basophil bodies which undergo fragmentation; formerly (technique and reference as in 1) the basophil nucleolus and the basophil bodies originating from it were termed ‘nuclear material’ undergoing fragmentation. While this basophil nucleolar material presents a fragmented appearance, it increases in amount as evidenced by the large number of basophil bodies present in the older nurse-cell nuclei. This material is utilized for the nourishment of the egg after the latter engulfs the nurse-cell nuclei. Nucleolar extrusions to the cytoplasm do not occur. 3. The behaviour of the chromatin of the follicle-cell nuclei is similar to that of the nurse-cell nuclei except that in Allantus pallipes the nuclear chromatin network as demonstrated by Feulgen's technique disappears in the older cells. 4. The nucleoli of the follicle-cells are basophil. They become broken up in the older cells, but in most cases the resulting masses remain in contact. Nucleolar extrusions to the cytoplasm do not occur. 5. The occurrence of deeply basophil material in the cytoplasm of the follicle-cells of Thrinax mixta stained with Mann's methyl-blue eosin, formerly described for Bouin fixed material stained in iron haematoxylin (9), suggests that some substance in solution may be passed into the ooplasm; extrusion of granules from the follicle-cells to the ooplasm does not take place. 6. The absence or non-visibility of chromatin (Feulgen's technique) from the oocytes of Thrinax mixta, and its disappearance from the older oocytes of Allantus pallipes , would indicate that the chromatin undergoes a chemical change during oogenesis such as suggested by Koch for Chilopods. 7. The oxyphil and basophil nucleoli of the oocytes do not react to Feulgen's technique for chromatin; this agrees with Ludford's findings for the mouse and for Limnaeastagnalis.

Mechanisms of Gurken-dependentpiperegulation and the robustness of dorsoventral patterning inDrosophila

Development ◽  
2002 ◽  
Vol 129 (12) ◽  
pp. 2965-2975 ◽  
Author(s):  
Francesca Peri ◽  
Martin Technau ◽  
Siegfried Roth
Keyword(s):  
Egf Receptor ◽  
Follicle Cell ◽  
Dorsal Side ◽  
Drosophila Embryo ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Axis Formation ◽  
Embryonic Patterning ◽  
Cell Fates ◽  
Egg Chamber

The restriction of Pipe, a potential glycosaminoglycan-modifying enzyme, to ventral follicle cells of the egg chamber is essential for dorsoventral axis formation in the Drosophila embryo. pipe repression depends on the TGFα-like ligand Gurken, which activates the Drosophila EGF receptor in dorsal follicle cells. An analysis of Raf mutant clones shows that EGF signalling is required cell-autonomously in all dorsal follicle cells along the anteroposterior axis of the egg chamber to repress pipe. However, the autoactivation of EGF signalling important for dorsal follicle cell patterning has no influence on pipe expression. Clonal analysis shows that also the mirror-fringe cassette suggested to establish a secondary signalling centre in the follicular epithelium is not involved in pipe regulation. These findings support the view that the pipe domain is directly delimited by a long-range Gurken gradient. Pipe induces ventral cell fates in the embryo via activation of the Spätzle/Toll pathway. However, large dorsal patches of ectopic pipe expression induced by Raf clones rarely affect embryonic patterning if they are separated from the endogenous pipe domain. This indicates that potent inhibitory processes prevent pipe dependent Toll activation at the dorsal side of the egg.

Memoirs: The Rôles of the Nurse-cells, Oocytes and Follicle-cells in Tenthredinid Oogenesis

1928 ◽  
Vol s2-71 (284) ◽  
pp. 541-561
Author(s):  
A. D. PEACOCK ◽  
R.A. R. GRESSON
Keyword(s):  
Nuclear Membrane ◽  
Nurse Cell ◽  
Follicle Cell ◽  
Narrow Channel ◽  
Nuclear Material ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Accessory Nuclei ◽  
Dark Staining ◽  
The Common

1. Ovary formation in Tenthredinidae follows the general hymenopterous plan. 2. Nurse-cell phenomena are as follows: the nuclei of the first nutritive chamber are surrounded by a chromatin cloud and many of them contain irregular darkly-staining masses of nuclear material, which masses may also be present in the riper chambers; the granules given off from the nuclei into the chromatin cloud eventually become surrounded by a vesicle and give rise to the ‘secondary’ or ‘accessory’ nuclei. 3. Oocyte nucleolar phenomena show the following: the nucleoli in Thrinax mixta and Platycampus luridiventris give rise to buds which become free; in one case buds were observed close to the inner surface of the nuclear membrane in Allantus (Emphytus) pallipes are shown what are apparently later stages of this process, viz. the passage of the buds through the nuclear membrane into the egg substance and their formation there into accessory nuclei. 4. The fate of the nurse-cells is shown in the older nutritive chambers and oocytes--the cell boundaries become indistinct and some of the cytoplasm, together with contained accessory nuclei, passes by a narrow channel into the oocyte. The cytoplasmic flow becomes more marked in the last chamber. In the final stages, shown in the last chamber, all the cells lose their boundaries and the common cytoplasm passes into the oocyte, carrying with it the free nuclei to their engulfment and absorption in the ooplasm. 5. Some of the follicle-cells surrounding the last oocyte in Pristiphora padi, and the fifth, sixth, and seventh of Thrinax mixta, contain granular dark-staining material which may completely fill the cell, these granules probably originating from the nucleus. They pass out of the follicle-cell into the egg where they become surrounded by vesicles, and, finally, present an appearance indistinguishable from that of accessory nuclei. 6. Secondary or accessory nuclei, therefore, have a threefold origin, namely, from the nuclei, of nurse-cells and oocytes and from follicle-cells, their source of derivation in the last being the follicular nuclei. 7. The follicle-cells of the distal pole of the last oocyte of one ovariole of Pristiphora padi have processes which insinuate themselves into the ooplasm. 8. The phenomena of oogenesis described in these four species of sawflies, while embracing certain which have not hitherto been recorded, conform, in essentials, with those already discovered for Hymenoptera generally.

Evidence for a highly selective RNA transport system and its role in establishing the dorsoventral axis of the Drosophila egg

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 653-661 ◽  
Author(s):  
H.K. Cheung ◽  
T.L. Serano ◽  
R.S. Cohen
Keyword(s):  
Dorsal Surface ◽  
Drosophila Embryo ◽  
Follicle Cells ◽  
Oocyte Nucleus ◽  
Axis Formation ◽  
Asymmetric Distribution ◽  
Rna Transport ◽  
Nurse Cells ◽  
Dorsoventral Axis ◽  
Multistep Process

The specification of cell fates along the dorsoventral axis of the Drosophila embryo is dependent on the asymmetric distribution of proteins within the egg and within the egg's outer membranes. Such asymmetries arise during oogenesis and are dependent on multiple cell-cell interactions between the developing oocyte and its neighboring somatic follicle cells. The earliest known such interaction involves the generation of a signal in the oocyte and its reception in the follicle cells lying on the dorsal surface of the oocyte at approximately stage 10 of oogenesis. Several independent lines of investigation indicate that the fs(1)K10 (K10) gene negatively regulates the synthesis of the signal in the oocyte nucleus. Here we present data that indicate that the accumulation of K10 protein in the oocyte nucleus is a multistep process involving: (1) the synthesis of K10 RNA in nurse cells, (2) the rapid transport of K10 RNA from nurse cells into the oocyte, (3) the localization of K10 RNA to the anterior margin of the oocyte, and (4) K10 protein synthesis and localization. K10 RNA is transported into the oocyte continuously beginning at approximately stage 2. This indicates a high degree of selectivity in transport, since most RNAs synthesized in stage 2 and older nurse cells are stored there until stage 11, when nurse cells donate their entire cytoplasm to the oocyte. The sequences responsible for the early (pre-stage 11) and selective transport of K10 RNA into the oocyte map to the 3' transcribed non-translated region of the gene. None of the other identified genes involved in dorsoventral axis formation are required for K10 RNA transport.(ABSTRACT TRUNCATED AT 250 WORDS)

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