Multiple nucleoli and enhanced nucleolar activity in the nurse cells of the insect ovary

Chromosoma ◽  
1969 ◽  
Vol 27 (2) ◽  
pp. 178-197 ◽  
Author(s):  
Dietrich Ribbert ◽  
Karlheinz Bier
Keyword(s):  
Nurse Cells ◽  
Nucleolar Activity ◽  
Insect Ovary

Isolation of microtubule motors from an insect ovarian system: characterization using a novel motility substratum

1990 ◽  
Vol 96 (1) ◽  
pp. 63-69
Author(s):  
ANGELA ANASTASI ◽  
CHERRYL HUNT ◽  
HOWARD STEBBINGS
Keyword(s):  
Nurse Cells ◽  
Single Fraction ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
System Characterization ◽  
Associated Proteins ◽  
Insect Ovary

The ovaries of hemipteran insects contain massive microtubule-based translocation channels known as nutritive tubes, linking nurse cells to the developing oocytes. Translocation, which is in a retrograde direction along the nutritive tube microtubules, has previously been reactivated in vitro. Here, ATPsensitive microtubule-associated proteins (MAPs) have been isolated from the insect ovaries, and beads coated with such proteins applied to salt-treated, detergent-extracted nutritive tube microtubules microdissected from the insect ovaries. These motility substrata are composed of many thousands of parallel microtubules, all with a common known polarity, so that not only are they easily observed, but the direction of any translocation along their length can be readily interpreted. ATP extracts of insect ovarian MAPs, containing both kinesin and dynein, were seen to promote bidirectional movements of beads. Movements in the two directions differed in both rate and form. On fractionation of the ATP extract, those fractions containing kinesin brought about bead movement in an anterograde direction. Fractions containing dynein failed to promote movement of beads, and no single fraction promoted movement of beads in a retrograde direction. Kinesin, while clearly present in the insect ovary, is absent from the nutritive tube translocation channels. The nutritive tubes, however, contain a polypeptide that co-electrophoreses with insect ovarian dynein, making dynein a possible candidate for the motor that drives the retrograde translocation along nutritive tubes.

scholarly journals Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

2016 ◽  
Vol 113 (34) ◽  
pp. E4995-E5004 ◽  
Author(s):  
Wen Lu ◽  
Michael Winding ◽  
Margot Lakonishok ◽  
Jill Wildonger ◽  
Vladimir I. Gelfand
Keyword(s):  
Cytoplasmic Streaming ◽  
Cell Types ◽  
Nurse Cells ◽  
Wild Type ◽  
Actin Cortex ◽  
Microtubule Motor ◽  
Multiple Cell ◽  
Cytoplasmic Microtubules ◽  
Two Populations

Cytoplasmic streaming in Drosophila oocytes is a microtubule-based bulk cytoplasmic movement. Streaming efficiently circulates and localizes mRNAs and proteins deposited by the nurse cells across the oocyte. This movement is driven by kinesin-1, a major microtubule motor. Recently, we have shown that kinesin-1 heavy chain (KHC) can transport one microtubule on another microtubule, thus driving microtubule–microtubule sliding in multiple cell types. To study the role of microtubule sliding in oocyte cytoplasmic streaming, we used a Khc mutant that is deficient in microtubule sliding but able to transport a majority of cargoes. We demonstrated that streaming is reduced by genomic replacement of wild-type Khc with this sliding-deficient mutant. Streaming can be fully rescued by wild-type KHC and partially rescued by a chimeric motor that cannot move organelles but is active in microtubule sliding. Consistent with these data, we identified two populations of microtubules in fast-streaming oocytes: a network of stable microtubules anchored to the actin cortex and free cytoplasmic microtubules that moved in the ooplasm. We further demonstrated that the reduced streaming in sliding-deficient oocytes resulted in posterior determination defects. Together, we propose that kinesin-1 slides free cytoplasmic microtubules against cortically immobilized microtubules, generating forces that contribute to cytoplasmic streaming and are essential for the refinement of posterior determinants.

scholarly journals Thymic nurse cells exhibit epithelial progenitor phenotype and create unique extra-cytoplasmic membrane space for thymocyte selection

2010 ◽  
Vol 261 (2) ◽  
pp. 81-92 ◽  
Author(s):  
Tonya M. Hendrix ◽  
Rajendra V.E. Chilukuri ◽  
Marcia Martinez ◽  
Zachariah Olushoga ◽  
Andrew Blake ◽  
...  
Keyword(s):  
Cytoplasmic Membrane ◽  
Nurse Cells ◽  
Thymic Nurse Cells

The extracellular electrical current pattern and its variability in vitellogenic Drosophila follicles

1986 ◽  
Vol 81 (1) ◽  
pp. 189-206 ◽  
Author(s):  
J. Bohrmann ◽  
A. Dorn ◽  
K. Sander ◽  
H. Gutzeit
Keyword(s):  
Juvenile Hormone ◽  
Current Density ◽  
Developmental Stages ◽  
Electrical Current ◽  
Posterior Pole ◽  
The Other ◽  
Follicular Epithelium ◽  
Nurse Cells ◽  
Vibrating Probe ◽  
Current Pattern

We determined the extracellular electrical current pattern around Drosophila follicles at different developmental stages (7–14) with a vibrating probe. At most stages a characteristic pattern can be recognized: current leaves near the oocyte end of the follicle and enters at the nurse cells. Only at late vitellogenic stages was an inward-directed current located at the posterior pole of many follicles. Most striking was the observed heterogeneity both in current pattern and in current density between follicles of the same stage. Different media (changed osmolarity or pH, addition of cytoskeletal inhibitors or juvenile hormone) were tested for their effects on extrafollicular currents. The current density was consistently influenced by the osmolarity of the medium but not by the other parameters tested. Denuded nurse cells (follicular epithelium locally stripped off) show current influx, while an accidentally denuded oocyte produced no current. Our results show that individual follicles may be electrophysiologically different, though their uniform differentiation during vitellogenesis does not reflect such heterogeneity.

Apoptosis in late stage Drosophila nurse cells does not require genes within the H99 deficiency

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1075-1082 ◽  
Author(s):  
K. Foley ◽  
L. Cooley
Keyword(s):  
Dna Fragmentation ◽  
Late Stage ◽  
Expression Patterns ◽  
Nuclear Material ◽  
Nurse Cells ◽  
Wild Type ◽  
Negative Regulators ◽  
Egg Chambers ◽  
Positive Regulators ◽  
Egg Chamber

We have determined that nurse cells are cleared from the Drosophila egg chamber by apoptosis. DNA fragmentation begins in nurse cells at stage 12, following the completion of cytoplasm transfer from the nurse cells to the oocyte. During stage 13, nurse cells increasingly contain highly fragmented DNA and disappear from the egg chamber concomitantly with the formation of apoptotic vesicles containing highly fragmented nuclear material. In dumpless mutant egg chambers that fail to complete cytoplasm transport from the nurse cells, DNA fragmentation is markedly delayed and begins during stage 13, when the majority of cytoplasm is lost from the nurse cells. These data suggest the presence of cytoplasmic factors in nurse cells that inhibit the initiation of DNA fragmentation. In addition, we have examined the ovarian expression patterns of regulatory genes implicated in Drosophila apoptosis. The positive regulators, reaper (rpr), head involution defective (hid) and grim, as well as the negative regulators, DIAP1 and DIAP2, are transcribed during oogenesis. However, germline clones homozygous for the deficiency Df(3)H99, which deletes rpr, hid and grim, undergo oogenesis in a manner morphologically indistinguishable from wild type, indicating that genes within this region are not necessary for apoptosis in nurse cells.

Evidence against electrophoresis as the principal mode of protein transport in vitellogenic ovarian follicles of Drosophila

Development ◽  
1987 ◽  
Vol 101 (2) ◽  
pp. 279-288
Author(s):  
J. Bohrmann ◽  
H. Gutzeit
Keyword(s):  
Nurse Cell ◽  
Protein Transport ◽  
Exchange Chromatography ◽  
Heterologous Proteins ◽  
Nurse Cells ◽  
Cell Cytoplasm ◽  
Two Dimensional Gel Electrophoresis ◽  
Electrophoretic Transport ◽  
Indicator Dyes

Charged cell constituents in polytrophic insect follicles are thought to be transported in the nurse cell-oocyte syncytium by way of electrophoresis. This concept, proposed by Woodruff & Telfer (1980) was based on electrophysiological data and microinjection of heterologous proteins using Hyalophora follicles. By microinjecting fluorescently labelled acidic and basic proteins into the nurse cells or oocyte of vitellogenic Drosophila follicles, we failed to obtain evidence for charge-dependent migration of these molecules. We have also analyzed the proteins of nurse cells and oocyte on isoelectric focusing gels, by means of two-dimensional gel electrophoresis, and by ion exchange chromatography to see if basic or acidic proteins accumulate in vivo in nurse cells and oocyte, respectively. For the bulk of the follicular proteins we found no accumulation. Further evidence against an electrophoretic transport system in Drosophila was obtained by estimating the intracellular pH from the colour of indicator dyes microinjected into the follicles; the results indicate that the pH in the nurse cell cytoplasm is lower than that in the ooplasm. According to the model developed for Hyalophora, electrophoretic transport would be favoured by high pH in the nurse cell cytoplasm.

scholarly journals Nurse cell-derived small RNAs define paternal epigenetic inheritance in Arabidopsis

2021 ◽  
Author(s):  
Jincheng Long ◽  
James Walker ◽  
Wenjing She ◽  
Billy Aldridge ◽  
Hongbo Gao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Nurse Cell ◽  
De Novo ◽  
Epigenetic Inheritance ◽  
Genome Integrity ◽  
Nurse Cells ◽  
Male Germline ◽  
Methylation Patterns

AbstractThe plant male germline undergoes DNA methylation reprogramming, which methylates genes de novo and thereby alters gene expression and facilitates meiosis. Why reprogramming is limited to the germline and how specific genes are chosen is unknown. Here, we demonstrate that genic methylation in the male germline, from meiocytes to sperm, is established by germline-specific siRNAs transcribed from transposons with imperfect sequence homology. These siRNAs are synthesized by meiocyte nurse cells (tapetum) via activity of the tapetum-specific chromatin remodeler CLASSY3. Remarkably, tapetal siRNAs govern germline methylation throughout the genome, including the inherited methylation patterns in sperm. Finally, we demonstrate that these nurse cell-derived siRNAs (niRNAs) silence germline transposons, thereby safeguarding genome integrity. Our results reveal that tapetal niRNAs are sufficient to reconstitute germline methylation patterns and drive extensive, functional methylation reprogramming analogous to piRNA-mediated reprogramming in animal germlines.

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