scholarly journals The C. elegans gonadal sheath Sh1 cells associate selectively with a differentiating germ cell population in the proliferative zone

2021 ◽  
Author(s):  
Xin Li ◽  
Noor Singh ◽  
Camille Miller ◽  
India Washington ◽  
Bintou Sosseh ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Line ◽  
Fluorescent Proteins ◽  
Temperature Sensitive ◽  
Variable Expression ◽  
C Elegans ◽  
Proliferative Zone ◽  
Adult Hermaphrodite ◽  
Sheath Cells

The C. elegans adult hermaphrodite germ line is surrounded by a thin tube formed by somatic sheath cells that support germ cells as they mature from the stem-like mitotic state through meiosis, gametogenesis and ovulation. Recently, we discovered that the distal-most Sh1 sheath cells associate with mitotic germ cells as they exit the niche. Here we report that these distal sheath-associated germ cells differentiate first in animals with temperature-sensitive mutations affecting germ cell state, and stem-like germ cells are maintained distal to the Sh1 boundary. We analyze several markers of the distal sheath, which is best visualized with endogenously tagged membrane proteins, as overexpressed fluorescent proteins fail to localize to distal membrane processes and can cause gonad morphology defects. However, such reagents with highly variable expression can be used to determine the relative positions of the two Sh1 cells, one of which often extends further distal than the other.

scholarly journals Functional Recovery of the Germ Line Following Splicing Collapse

2021 ◽  
Author(s):  
Wei Cao ◽  
Christopher Tran ◽  
Stuart K Archer ◽  
Sandeep Gopal ◽  
Roger Pocock
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Rna Splicing ◽  
Messenger Rna ◽  
Germ Line ◽  
Intron Retention ◽  
Mrna Splicing ◽  
C Elegans ◽  
Mrna Transcripts ◽  
Line Following

Splicing introns from precursor-messenger RNA (pre-mRNA) transcripts is essential for translating functional proteins. Here, we report that the previously uncharacterized Caenorhabditis elegans protein MOG-7, acts as a pre-mRNA splicing factor. Depleting MOG-7 from the C. elegans germ line causes intron retention in the majority of germline-expressed genes, impeding the germ cell cycle, and causing defects in nuclear morphology, germ cell identity and sterility. Despite the deleterious consequences caused by MOG-7 loss, the adult germ line can functionally recover to produce viable and fertile progeny when MOG-7 is restored. Germline recovery is dependent on a burst of apoptosis that likely clears defective germ cells, and viable gametes generated from the proliferation of germ cells in the progenitor zone. Together, these findings reveal that MOG-7 is essential for germ cell development, and that the germ line is able to functionally recover after a collapse in RNA splicing.

scholarly journals glp-3 Is Required for Mitosis and Meiosis in the Caenorhabditis elegans Germ Line

Genetics ◽  
1997 ◽  
Vol 145 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Lisa C Kadyk ◽  
Eric J Lambie ◽  
Judith Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Germ Line ◽  
Stem Cell Population ◽  
Phenotypic Characterization ◽  
Loss Of Function ◽  
Dapi Staining ◽  
Cell Cycles ◽  
C Elegans ◽  
Mitosis And Meiosis

The germ line is the only tissue in Caenorhabditis elegans in which a stem cell population continues to divide mitotically throughout life; hence the cell cycles of the germ line and the soma are regulated differently. Here we report the genetic and phenotypic characterization of the glp-3 gene. In animals homozygous for each of five recessive loss-of-function alleles, germ cells in both hermaphrodites and males fail to progress through mitosis and meiosis, but somatic cells appear to divide normally. Germ cells in animals grown at 15° appear by DAPI staining to be uniformly arrested at the G2/M transition with <20 germ cells per gonad on average, suggesting a checkpoint-mediated arrest. In contrast, germ cells in mutant animals grown at 25° frequently proliferate slowly during adulthood, eventually forming small germ lines with several hundred germ cells. Nevertheless, cells in these small germ lines never undergo meiosis. Double mutant analysis with mutations in other genes affecting germ cell proliferation supports the idea that glp-3 may encode a gene product that is required for the mitotic and meiotic cell cycles in the C. elegans germ line.

scholarly journals Genetic control of programmed cell death in the Caenorhabditis elegans hermaphrodite germline

Development ◽  
1999 ◽  
Vol 126 (5) ◽  
pp. 1011-1022 ◽  
Author(s):  
T.L. Gumienny ◽  
E. Lambie ◽  
E. Hartwieg ◽  
H.R. Horvitz ◽  
M.O. Hengartner
Keyword(s):  
Cell Death ◽  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Somatic Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Mapk Pathway ◽  
Apoptotic Cell ◽  
C Elegans ◽  
Pathway Activation

Development of the nematode Caenorhabditis elegans is highly reproducible and the fate of every somatic cell has been reported. We describe here a previously uncharacterized cell fate in C. elegans: we show that germ cells, which in hermaphrodites can differentiate into sperm and oocytes, also undergo apoptotic cell death. In adult hermaphrodites, over 300 germ cells die, using the same apoptotic execution machinery (ced-3, ced-4 and ced-9) as the previously described 131 somatic cell deaths. However, this machinery is activated by a distinct pathway, as loss of egl-1 function, which inhibits somatic cell death, does not affect germ cell apoptosis. Germ cell death requires ras/MAPK pathway activation and is used to maintain germline homeostasis. We suggest that apoptosis eliminates excess germ cells that acted as nurse cells to provide cytoplasmic components to maturing oocytes.

Melting dsDNA donor molecules potentiates precision genome editing in C. elegans

2020 ◽  
Author(s):  
Krishna S. Ghanta ◽  
Craig C. Mello
Keyword(s):  
Caenorhabditis Elegans ◽  
Genome Editing ◽  
Germ Cells ◽  
Multiple Injections ◽  
C Elegans ◽  
Homology Directed Repair ◽  
Selection Strategies ◽  
Double Stranded Dna ◽  
Adult Hermaphrodite

ABSTRACTCRISPR genome editing has revolutionized genetics in many organisms. In the nematode Caenorhabditis elegans one injection into each of the two gonad arms of an adult hermaphrodite exposes hundreds of meiotic germ cells to editing mixtures, permitting the recovery of multiple indels or small precision edits from each successfully injected animal. Unfortunately, particularly for long insertions, editing efficiencies can vary widely, necessitating multiple injections, and often requiring co-selection strategies. Here we show that melting double stranded DNA (dsDNA) donor molecules prior to injection increases the frequency of precise homology-directed repair (HDR) by several fold for longer edits. We describe troubleshooting strategies that enable consistently high editing efficiencies resulting, for example, in up to 100 independent GFP knock-ins from a single injected animal. These efficiencies make C. elegans by far the easiest metazoan to genome edit, removing barriers to the use and adoption of this facile system as a model for understanding animal biology.

scholarly journals Progression from a stem cell–like state to early differentiation in the C. elegans germ line

2010 ◽  
Vol 107 (5) ◽  
pp. 2048-2053 ◽  
Author(s):  
Olivier Cinquin ◽  
Sarah L. Crittenden ◽  
Dyan E. Morgan ◽  
Judith Kimble
Keyword(s):  
Stem Cell ◽  
Germ Cells ◽  
Cell Biology ◽  
Germ Line ◽  
Stem Cell Biology ◽  
Self Renewal ◽  
Early Differentiation ◽  
C Elegans ◽  
Stem Cell Maintenance ◽  
System A

Controls of stem cell maintenance and early differentiation are known in several systems. However, the progression from stem cell self-renewal to overt signs of early differentiation is a poorly understood but important problem in stem cell biology. The Caenorhabditis elegans germ line provides a genetically defined model for studying that progression. In this system, a single-celled mesenchymal niche, the distal tip cell (DTC), employs GLP-1/Notch signaling and an RNA regulatory network to balance self-renewal and early differentiation within the “mitotic region,” which continuously self-renews while generating new gametes. Here, we investigate germ cells in the mitotic region for their capacity to differentiate and their state of maturation. Two distinct pools emerge. The “distal pool” is maintained by the DTC in an essentially uniform and immature or “stem cell–like” state; the “proximal pool,” by contrast, contains cells that are maturing toward early differentiation and are likely transit-amplifying cells. A rough estimate of pool sizes is 30–70 germ cells in the distal immature pool and ≈150 in the proximal transit-amplifying pool. We present a simple model for how the network underlying the switch between self-renewal and early differentiation may be acting in these two pools. According to our model, the self-renewal mode of the network maintains the distal pool in an immature state, whereas the transition between self-renewal and early differentiation modes of the network underlies the graded maturation of germ cells in the proximal pool. We discuss implications of this model for controls of stem cells more broadly.

scholarly journals Novel LOTUS-domain proteins are organizational hubs that recruit C. elegans Vasa to germ granules

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Patricia Giselle Cipriani ◽  
Olivia Bay ◽  
John Zinno ◽  
Michelle Gutwein ◽  
Hin Hark Gan ◽  
...  
Keyword(s):  
Rna Processing ◽  
Germ Line ◽  
Temperature Sensitive ◽  
Developmental Transitions ◽  
P Granules ◽  
C Elegans ◽  
Intrinsically Disordered ◽  
Meiotic Progression ◽  
Intrinsically Disordered Regions ◽  
Granule Growth

We describe MIP-1 and MIP-2, novel paralogous C. elegans germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.

scholarly journals Hatched and starved: Two chromatin compaction mechanisms join forces to silence germ cell genome

2021 ◽  
Vol 220 (9) ◽  
Author(s):  
Ana Karina Morao ◽  
Sevinc Ercan
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Nutrient Availability ◽  
Food Shortage ◽  
Chromatin Compaction ◽  
C Elegans ◽  
Cell Genome

Animals evolved in environments with variable nutrient availability and one form of adaptation is the delay of reproduction in food shortage conditions. Belew et al. (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202009197) report that in the nematode C. elegans, starvation-induced transcriptional quiescence in germ cells is achieved through a pathway that combines two well-known chromatin compaction mechanisms.

scholarly journals fog-1, a regulatory gene required for specification of spermatogenesis in the germ line of Caenorhabditis elegans.

Genetics ◽  
1990 ◽  
Vol 125 (1) ◽  
pp. 29-39 ◽  
Author(s):  
M K Barton ◽  
J Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Germ Line ◽  
Regulatory Gene ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Male Germ Line ◽  
Somatic Tissues ◽  
Lines Of Evidence

Abstract In wild-type Caenorhabditis elegans, the XO male germ line makes only sperm and the XX hermaphrodite germ line makes sperm and then oocytes. In contrast, the germ line of either a male or a hermaphrodite carrying a mutation of the fog-1 (feminization of the germ line) locus is sexually transformed: cells that would normally make sperm differentiate as oocytes. However, the somatic tissues of fog-1 mutants remain unaffected. All fog-1 alleles identified confer the same phenotype. The fog-1 mutations appear to reduce fog-1 function, indicating that the wild-type fog-1 product is required for specification of a germ cell as a spermatocyte. Two lines of evidence indicate that a germ cell is determined for sex at about the same time that it enters meiosis. These include the fog-1 temperature sensitive period, which coincides in each sex with first entry into meiosis, and the phenotype of a fog-1; glp-1 double mutant. Experiments with double mutants show that fog-1 is epistatic to mutations in all other sex-determining genes tested. These results lead to the conclusion that fog-1 acts at the same level as the fem genes at the end of the sex determination pathway to specify germ cells as sperm.

The fog-3 gene and regulation of cell fate in the germ line of Caenorhabditis elegans.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 561-577 ◽  
Author(s):  
R E Ellis ◽  
J Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Sexual Identity ◽  
Cell Fate ◽  
Germ Cells ◽  
Regulatory Network ◽  
Germ Line ◽  
The Other ◽  
Nematode Caenorhabditis Elegans ◽  
Inhibitory Interactions

Abstract In the nematode Caenorhabditis elegans, germ cells normally adopt one of three fates: mitosis, spermatogenesis or oogenesis. We have identified and characterized the gene fog-3, which is required for germ cells to differentiate as sperm rather than as oocytes. Analysis of double mutants suggests that fog-3 is absolutely required for spermatogenesis and acts at the end of the regulatory hierarchy controlling sex determination for the germ line. By contrast, mutations in fog-3 do not alter the sexual identity of other tissues. We also have characterized the null phenotype of fog-1, another gene required for spermatogenesis; we demonstrate that it too controls the sexual identity of germ cells but not of other tissues. Finally, we have studied the interaction of these two fog genes with gld-1, a gene required for germ cells to undergo oogenesis rather than mitosis. On the basis of these results, we propose that germ-cell fate might be controlled by a set of inhibitory interactions among genes that specify one of three fates: mitosis, spermatogenesis or oogenesis. Such a regulatory network would link the adoption of one germ-cell fate to the suppression of the other two.

scholarly journals C. elegans Anillin proteins regulate intercellular bridge stability and germline syncytial organization

2014 ◽  
Vol 206 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Rana Amini ◽  
Eugénie Goupil ◽  
Sara Labella ◽  
Monique Zetka ◽  
Amy S. Maddox ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Germ Cells ◽  
Cytoplasmic Streaming ◽  
Intercellular Bridge ◽  
Cell Specification ◽  
Intercellular Bridges ◽  
C Elegans ◽  
Daughter Cells ◽  
Germ Cell Specification

Cytokinesis generally produces two separate daughter cells, but in some tissues daughter nuclei remain connected to a shared cytoplasm, or syncytium, through incomplete cytokinesis. How syncytia form remains poorly understood. We studied syncytial formation in the Caenorhabditis elegans germline, in which germ cells connect to a shared cytoplasm core (the rachis) via intercellular bridges. We found that syncytial architecture initiates early in larval development, and germ cells become progressively interconnected until adulthood. The short Anillin family scaffold protein ANI-2 is enriched at intercellular bridges from the onset of germ cell specification, and ANI-2 loss resulted in destabilization of intercellular bridges and germ cell multinucleation defects. These defects were partially rescued by depleting the canonical Anillin ANI-1 or blocking cytoplasmic streaming. ANI-2 is also required for elastic deformation of the gonad during ovulation. We propose that ANI-2 promotes germ cell syncytial organization and allows for compensation of the mechanical stress associated with oogenesis by conferring stability and elasticity to germ cell intercellular bridges.

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