The Drosophila gene fs(2)cup interacts with otu to define a cytoplasmic pathway required for the structure and function of germ-line chromosomes

Development ◽  
1997 ◽  
Vol 124 (7) ◽  
pp. 1419-1431 ◽  
Author(s):  
L.N. Keyes ◽  
A.C. Spradling
Keyword(s):  
Nurse Cell ◽  
Germ Line ◽  
Meiotic Chromosome ◽  
Cyst Formation ◽  
Nurse Cells ◽  
Egg Maturation ◽  
Cytoplasmic Proteins ◽  
Acid Protein ◽  
Membrane Spanning ◽  
And Function

The Drosophila ovarian tumor gene (otu) encodes cytoplasmic proteins that are required in germ-line cells for cyst formation, nurse cell chromosome structure and egg maturation. We have analyzed a gene, fs(2)cup, that participates in many of the same processes and interacts with otu genetically. Both nurse cell and oocyte chromosomes require cup to attain a normal morphology. In addition, the gene is needed for the oocyte to grow normally by taking up materials transported from the nurse cells. The gene encodes a 1132-amino-acid protein containing a putative membrane-spanning domain. Cup protein (but not cup RNA) is transported selectively into the oocyte in germarial cysts, like the p104 Otu protein. It is strongly associated with large structures in the cytoplasm and perinuclear region of nurse cells and, like Otu, moves to the periphery of these cells in stages 9–10. Moreover, cup mutations dominantly disrupt meiotic chromosome segregation. We propose that cup, otu and another interacting gene, fs(2)B, take part in a common cytoplasmic pathway with multiple functions during oogenesis.

scholarly journals Morphology of Mitochondria in Syncytial Annelid Female Germ-Line Cyst Visualized by Serial Block-Face SEM

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Anna Z. Urbisz ◽  
Sebastian Student ◽  
Małgorzata A. Śliwińska ◽  
Karol Małota
Keyword(s):  
Nurse Cell ◽  
Germ Line ◽  
Close Association ◽  
Three Dimensional ◽  
Nurse Cells ◽  
Cytoplasmic Bridges ◽  
Block Face ◽  
Female Germ Line ◽  
Pass Through ◽  
Mitochondrial Networks

Mitochondria change their morphology and distribution depending on the metabolism and functional state of a cell. Here, we analyzed the mitochondria and selected structures in female germ-line cysts in a representative of clitellate annelids – the white worm Enchytraeus albidus in which each germ cell has one cytoplasmic bridge that connects it to a common cytoplasmic mass. Using serial block-face scanning electron microscopy (SBEM), we prepared three-dimensional ultrastructural reconstructions of the entire selected compartments of a cyst at the advanced stage of oogenesis, i.e. the nurse cell, cytophore, and cytoplasmic bridges of all 16 cells (15 nurse cells and oocyte). We revealed extensive mitochondrial networks in the nurse cells, cytophore and mitochondria that pass through the cytoplasmic bridges, which indicates that a mitochondrial network can extend throughout the entire cyst. The dynamic hyperfusion state was suggested for such mitochondrial aggregations. We measured the mitochondria distribution and revealed their polarized distribution in the nurse cells and more abundant accumulation within the cytophore compared to the nurse cell. A close association of mitochondrial networks with dispersed nuage material, which seems to be the structural equivalent of a Balbiani body, not described in clitellate annelids so far, was also revealed.

Toll-like receptors stimulate human neutrophil function

Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2660-2669 ◽  
Author(s):  
Fumitaka Hayashi ◽  
Terry K. Means ◽  
Andrew D. Luster
Keyword(s):  
Immune Cell ◽  
Germ Line ◽  
Quantitative Polymerase Chain Reaction ◽  
Neutrophil Function ◽  
Human Neutrophils ◽  
Toll Like Receptors ◽  
Gm Csf ◽  
Latex Beads ◽  
Macrophage Colony ◽  
And Function

Abstract The first immune cell to arrive at the site of infection is the neutrophil. Upon arrival, neutrophils quickly initiate microbicidal functions, including the production of antimicrobial products and proinflammatory cytokines that serve to contain infection. This allows the acquired immune system enough time to generate sterilizing immunity and memory. Neutrophils detect the presence of a pathogen through germ line-encoded receptors that recognize microbe-associated molecular patterns. In vertebrates, the best characterized of these receptors are Toll-like receptors (TLRs). We have determined the expression and function of TLRs in freshly isolated human neutrophils. Neutrophils expressed TLR1, 2, 4, 5, 6, 7, 8, 9, and 10—all the TLRs except TLR3. Granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment increased TLR2 and TLR9 expression levels. The agonists of all TLRs expressed in neutrophils triggered or primed cytokine release, superoxide generation, and L-selectin shedding, while inhibiting chemotaxis to interleukin-8 (IL-8) and increasing phagocytosis of opsonized latex beads. The response to the TLR9 agonist nonmethylated CpG-motif-containing DNA (CpG DNA) required GM-CSF pretreatment, which also enhanced the response to the other TLR agonists. Finally, using quantitative polymerase chain reaction (QPCR), we demonstrate a chemokine expression profile that suggests that TLR-stimulated neutrophils recruit innate, but not acquired, immune cells to sites of infection. (Blood. 2003;102:2660-2669)

scholarly journals Structure and Function of the CFTR Chloride Channel

1999 ◽  
Vol 79 (1) ◽  
pp. S23-S45 ◽  
Author(s):  
DAVID N. SHEPPARD ◽  
MICHAEL J. WELSH
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Channel ◽  
Atp Hydrolysis ◽  
Current Knowledge ◽  
Structure And Function ◽  
Binding Domains ◽  
Transporter Family ◽  
Membrane Spanning ◽  
And Function ◽  
R Domain

Sheppard, David N., and Michael J. Welsh. Structure and Function of the CFTR Chloride Channel. Physiol. Rev. 79 , Suppl.: S23–S45, 1999. — The cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ABC transporter family that forms a novel Cl− channel. It is located predominantly in the apical membrane of epithelia where it mediates transepithelial salt and liquid movement. Dysfunction of CFTR causes the genetic disease cystic fibrosis. The CFTR is composed of five domains: two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory (R) domain. Here we review the structure and function of this unique channel, with a focus on how the various domains contribute to channel function. The MSDs form the channel pore, phosphorylation of the R domain determines channel activity, and ATP hydrolysis by the NBDs controls channel gating. Current knowledge of CFTR structure and function may help us understand better its mechanism of action, its role in electrolyte transport, its dysfunction in cystic fibrosis, and its relationship to other ABC transporters.

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 Chromatin regulates expression of small RNAs to help maintain transposon methylome homeostasis in Arabidopsis

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Ranjith K. Papareddy ◽  
Katalin Páldi ◽  
Subramanian Paulraj ◽  
Ping Kao ◽  
Stefan Lutzmayer ◽  
...  
Keyword(s):  
Growth And Development ◽  
Germ Line ◽  
Small Interfering Rnas ◽  
Chromatin States ◽  
Heterochromatin Formation ◽  
Cellular Processes ◽  
A Cell ◽  
Decondensed Chromatin ◽  
And Function ◽  
New Generation

Abstract Background Eukaryotic genomes are partitioned into euchromatic and heterochromatic domains to regulate gene expression and other fundamental cellular processes. However, chromatin is dynamic during growth and development and must be properly re-established after its decondensation. Small interfering RNAs (siRNAs) promote heterochromatin formation, but little is known about how chromatin regulates siRNA expression. Results We demonstrate that thousands of transposable elements (TEs) produce exceptionally high levels of siRNAs in Arabidopsis thaliana embryos. TEs generate siRNAs throughout embryogenesis according to two distinct patterns depending on whether they are located in euchromatic or heterochromatic regions of the genome. siRNA precursors are transcribed in embryos, and siRNAs are required to direct the re-establishment of DNA methylation on TEs from which they are derived in the new generation. Decondensed chromatin also permits the production of 24-nt siRNAs from heterochromatic TEs during post-embryogenesis, and siRNA production from bipartite-classified TEs is controlled by their chromatin states. Conclusions Decondensation of heterochromatin in response to developmental, and perhaps environmental, cues promotes the transcription and function of siRNAs in plants. Our results indicate that chromatin-mediated siRNA transcription provides a cell-autonomous homeostatic control mechanism to help reconstitute pre-existing chromatin states during growth and development including those that ensure silencing of TEs in the future germ line.

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.

The endocycle controls nurse cell polytene chromosome structure during Drosophila oogenesis

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 293-303 ◽  
Author(s):  
K.J. Dej ◽  
A.C. Spradling
Keyword(s):  
Polytene Chromosome ◽  
Nurse Cell ◽  
Chromosome Structure ◽  
Polytene Chromosomes ◽  
S Phase ◽  
Nurse Cells ◽  
Chromosome Behavior ◽  
M Phase ◽  
Diploid Cells ◽  
Polytene Nuclei

Polytene chromosomes exhibit intricate higher order chromatin structure that is easily visualized due to their precisely aligned component strands. However, it remains unclear if the same factors determine chromatin organization in polyploid and diploid cells. We have analyzed one such factor, the cell cycle, by studying changes in Drosophila nurse cell chromosomes throughout the 10 to 12 endocycles of oogenesis. We find that nurse cells undergo three distinct types of endocycle whose parameters are correlated with chromosome behavior. The first four endocycles support complete DNA replication; poorly banded polytene euchromatin progressively condenses during the late S phases to produce blob-like chromosomes. During the unique fifth endocycle, an incomplete late S phase is followed by a mitosis-like state during which the 64C chromosomes dissociate into 32 chromatid pairs held together by unreplicated regions. All the subsequent endocycles lack any late S phase; during these cycles a new polytene chromosome grows from each 2C chromatid pair to generate 32-ploid polytene nuclei. These observations suggest that euchromatin begins to condense during late S phase and that nurse cell polytene chromosome structure is controlled by regulating whether events characteristic of late S and M phase are incorporated or skipped within a given endocycle.

The Drosophila fusome, a germline-specific organelle, contains membrane skeletal proteins and functions in cyst formation

Development ◽  
1994 ◽  
Vol 120 (4) ◽  
pp. 947-956 ◽  
Author(s):  
H. Lin ◽  
L. Yue ◽  
A.C. Spradling
Keyword(s):  
Cyst Formation ◽  
Nurse Cells ◽  
Germline Stem Cells ◽  
Cytoplasmic Structure ◽  
Ring Canals ◽  
Alpha Spectrin ◽  
Polarized Transport ◽  
Form Ring ◽  
Molecular Components ◽  
Number Of Cells

Oogenesis in Drosophila takes place within germline cysts that support polarized transport through ring canals interconnecting their 15 nurse cells and single oocyte. Developing cystocytes are spanned by a large cytoplasmic structure known as the fusome that has been postulated to help form ring canals and determine the pattern of nurse cell-oocyte interconnections. We identified the adducin-like hts product and alpha-spectrin as molecular components of fusomes, discovered a related structure in germline stem cells and documented regular associations between fusomes and cystocyte centrosomes. hts mutations completely eliminated fusomes, causing abnormal cysts containing a reduced number of cells to form. Our results imply that Drosophila fusomes are required for ovarian cyst formation and suggest that membrane skeletal proteins regulate cystocyte divisions.

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.

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