scholarly journals A ZYG-12–dynein interaction at the nuclear envelope defines cytoskeletal architecture in the C. elegans gonad

2009 ◽  
Vol 186 (2) ◽  
pp. 229-241 ◽  
Author(s):  
Kang Zhou ◽  
Melissa M. Rolls ◽  
David H. Hall ◽  
Christian J. Malone ◽  
Wendy Hanna-Rose
Keyword(s):  
Plasma Membrane ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Germ Cells ◽  
Nuclear Positioning ◽  
Microtubule Organization ◽  
Microtubule Network ◽  
C Elegans ◽  
Embryo Formation ◽  
Developmental Progression

Changes in cellular microtubule organization often accompany developmental progression. In the Caenorhabditis elegans embryo, the centrosome, which is attached to the nucleus via ZYG-12, organizes the microtubule network. In this study, we investigate ZYG-12 function and microtubule organization before embryo formation in the gonad. Surprisingly, ZYG-12 is dispensable for centrosome attachment in the germline. However, ZYG-12–mediated recruitment of dynein to the nuclear envelope is required to maintain microtubule organization, membrane architecture, and nuclear positioning within the syncytial gonad. We examined γ-tubulin localization and microtubule regrowth after depolymerization to identify sites of nucleation in germ cells. γ-Tubulin localizes to the plasma membrane in addition to the centrosome, and regrowth initiates at both sites. Because we do not observe organized microtubules around zyg-12(ct350) mutant nuclei with attached centrosomes, we propose that gonad architecture, including membrane and nuclear positioning, is determined by microtubule nucleation at the plasma membrane combined with tension on the microtubules by dynein anchored at the nucleus by ZYG-12.

scholarly journals A network of nuclear envelope proteins and cytoskeletal force generators mediates movements of and within nuclei throughout Caenorhabditis elegans development

2019 ◽  
Vol 244 (15) ◽  
pp. 1323-1332 ◽  
Author(s):  
Daniel A Starr
Keyword(s):  
Dna Damage ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Dna Damage Repair ◽  
Nuclear Migration ◽  
Envelope Proteins ◽  
Nuclear Positioning ◽  
C Elegans ◽  
Damage Repair

Nuclear migration and anchorage, together referred to as nuclear positioning, are central to many cellular and developmental events. Nuclear positioning is mediated by a conserved network of nuclear envelope proteins that interacts with force generators in the cytoskeleton. At the heart of this network are linker of nucleoskeleton and cytoskeleton (LINC) complexes made of Sad1 and UNC-84 (SUN) proteins at the inner nuclear membrane and Klarsicht, ANC-1, and Syne homology (KASH) proteins in the outer nuclear membrane. LINC complexes span the nuclear envelope, maintain nuclear envelope architecture, designate the surface of nuclei distinctly from the contiguous endoplasmic reticulum, and were instrumental in the early evolution of eukaryotes. LINC complexes interact with lamins in the nucleus and with various cytoplasmic KASH effectors from the surface of nuclei. These effectors regulate the cytoskeleton, leading to a variety of cellular outputs including pronuclear migration, nuclear migration through constricted spaces, nuclear anchorage, centrosome attachment to nuclei, meiotic chromosome movements, and DNA damage repair. How LINC complexes are regulated and how they function are reviewed here. The focus is on recent studies elucidating the best-understood network of LINC complexes, those used throughout Caenorhabditis elegans development. Impact statement Defects in nuclear positioning disrupt development in many mammalian tissues. In human development, LINC complexes play important cellular functions including nuclear positioning, homolog pairing in meiosis, DNA damage repair, wound healing, and gonadogenesis. The topics reviewed here are relevant to public health because defects in nuclear positioning and mutations in LINC components are associated with a wide variety of human diseases including muscular dystrophies, neurological disorders, progeria, aneurysms, hearing loss, blindness, sterility, and multiple cancers. Although this review focuses on findings in the model nematode Caenorhabditis elegans, the studies are relevant because almost all the findings originally made in C. elegans are conserved to humans. Furthermore, C. elegans remains the best described network for how LINC complexes are regulated and function.

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 A role for Rab5 in structuring the endoplasmic reticulum

2007 ◽  
Vol 178 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Anjon Audhya ◽  
Arshad Desai ◽  
Karen Oegema
Keyword(s):  
Endoplasmic Reticulum ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Rab Gtpases ◽  
C Elegans ◽  
Rab Family ◽  
Kinetics Of

The endoplasmic reticulum (ER) is a contiguous network of interconnected membrane sheets and tubules. The ER is differentiated into distinct domains, including the peripheral ER and nuclear envelope. Inhibition of two ER proteins, Rtn4a and DP1/NogoA, was previously shown to inhibit the formation of ER tubules in vitro. We show that the formation of ER tubules in vitro also requires a Rab family GTPase. Characterization of the 29 Caenorhabditis elegans Rab GTPases reveals that depletion of RAB-5 phenocopies the defects in peripheral ER structure that result from depletion of RET-1 and YOP-1, the C. elegans homologues of Rtn4a and DP1/NogoA. Perturbation of endocytosis by other means did not affect ER structure; the role of RAB-5 in ER morphology is thus independent of its well-studied requirement for endocytosis. RAB-5 and YOP-1/RET-1 also control the kinetics of nuclear envelope disassembly, which suggests an important role for the morphology of the peripheral ER in this process.

Three genes of the MAP kinase cascade, mek-2, mpk-1/sur-1 and let-60 ras, are required for meiotic cell cycle progression in Caenorhabditis elegans

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2525-2535 ◽  
Author(s):  
D.L. Church ◽  
K.L. Guan ◽  
E.J. Lambie
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Map Kinase ◽  
Germ Cells ◽  
Cell Cycle Progression ◽  
Extended Period ◽  
Meiotic Cell ◽  
Cycle Progression ◽  
C Elegans ◽  
Genetic Mosaic

In the germline of Caenorhabditis elegans hermaphrodites, meiotic cell cycle progression occurs in spatially restricted regions. Immediately after leaving the distal mitotic region, germ cells enter meiosis and thereafter remain in the pachytene stage of first meiotic prophase for an extended period. At the dorsoventral gonadal flexure, germ cells exit pachytene and subsequently become arrested in diakinesis. We have found that exit from pachytene is dependent on the function of three members of the MAP kinase signaling cascade. One of these genes, mek-2, is a newly identified C. elegans MEK (MAP kinase kinase). The other two genes, mpk-1/sur-1 (MAP kinase) and let-60 ras, were previously identified based on their roles in vulval induction and are shown here to act in combination with mek-2 to permit exit from pachytene. Through genetic mosaic analysis, we demonstrate that the expression of mpk-1/sur-1 is required within the germline to permit exit from pachytene.

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.

scholarly journals Tropomyosin and Troponin Are Required for Ovarian Contraction in the Caenorhabditis elegans Reproductive System

2004 ◽  
Vol 15 (6) ◽  
pp. 2782-2793 ◽  
Author(s):  
Kanako Ono ◽  
Shoichiro Ono
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Reproductive System ◽  
Regulatory Mechanism ◽  
Striated Muscle ◽  
Troponin C ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Somatic Gonad

Ovulation in the nematode Caenorhabditis elegans is coordinated by interactions between the somatic gonad and germ cells. Myoepithelial sheath cells of the proximal ovary are smooth muscle-like cells, but the regulatory mechanism of their contraction is unknown. We show that contraction of the ovarian muscle requires tropomyosin and troponin, which are generally major actin-linked regulators of contraction of striated muscle. RNA interference of tropomyosin or troponin C caused sterility by inhibiting ovarian contraction that is required for expelling mature oocytes into the spermatheca where fertilization takes place, thus causing accumulation of endomitotic oocytes in the ovary. Tropomyosin and troponin C were associated with actin filaments in the myoepithelial sheath, and the association of troponin C with actin was dependent on tropomyosin. A mutation in the actin depolymerizing factor/cofilin gene suppressed the ovulation defects by RNA interference of tropomyosin or troponin C. These results strongly suggest that tropomyosin and troponin are the actin-linked regulators for contraction of ovarian muscle in the C. elegans reproductive system.

scholarly journals Caenorhabditis elegans Nucleoporins Nup93 and Nup205 Determine the Limit of Nuclear Pore Complex Size Exclusion In Vivo

2003 ◽  
Vol 14 (12) ◽  
pp. 5104-5115 ◽  
Author(s):  
Vincent Galy ◽  
Iain W. Mattaj ◽  
Peter Askjaer
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Protein Import ◽  
Chromatin Condensation ◽  
Size Exclusion ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
C Elegans ◽  
Pore Complexes

Nuclear pore complexes (NPCs) span the nuclear envelope and mediate communication between the nucleus and the cytoplasm. To obtain insight into the structure and function of NPCs of multicellular organisms, we have initiated an extensive analysis of Caenorhabditis elegans nucleoporins. Of 20 assigned C. elegans nucleoporin genes, 17 were found to be essential for embryonic development either alone or in combination. In several cases, depletion of nucleoporins by RNAi caused severe defects in nuclear appearance. More specifically, the C. elegans homologs of vertebrate Nup93 and Nup205 were each found to be required for normal NPC distribution in the nuclear envelope in vivo. Depletion of Nup93 or Nup205 caused a failure in nuclear exclusion of nonnuclear macromolecules of ∼70 kDa without preventing active nuclear protein import or the assembly of the nuclear envelope. The defects in NPC exclusion were accompanied by abnormal chromatin condensation and early embryonic arrest. Thus, the contribution to NPC structure of Nup93 and Nup205 is essential for establishment of normal NPC function and for cell viability.

scholarly journals The isolation and in situ location of adligin: the microtubule cross-linking protein from Caenorhabditis elegans.

1989 ◽  
Vol 108 (3) ◽  
pp. 955-963 ◽  
Author(s):  
E Aamodt ◽  
R Holmgren ◽  
J Culotti
Keyword(s):  
Caenorhabditis Elegans ◽  
Structural Protein ◽  
Microtubule Network ◽  
C Elegans ◽  
Exclusion Chromatography ◽  
Associated Proteins ◽  
Cross Links ◽  
The Cross ◽  
Labeling Pattern

Microtubules isolated from the nematode Caenorhabditis elegans contain long stretches of periodic cross-links formed by microtubule-associated proteins (MAPs). These cross-links are 5.7 nm long, 3 nm wide, and occur at one tubulin dimer (8-nm) intervals along the walls of microtubules (Aamodt, E., and J. Culotti, 1986. J. Cell Biol. 103:23-31). The structural protein of the cross-links was isolated from the MAPs by centrifugation and exclusion chromatography. The cross-links were formed exclusively from the most prevalent MAP, a 32,000 mol wt protein. We suggest the name adligin for this MAP. Adligin eluted from the exclusion column at 33,000 mol wt indicating that it was a monomer in solution. Antibodies were made against the purified adligin and affinity purified. The affinity-purified antibodies were used to locate adligin in situ and to determine its distribution relative to that of tubulin by the use of double label immunofluorescence. The anti-adligin antibodies labeled a fibrous network in the cytoplasm of most cells of C. elegans. Neurons were labeled especially well. This labeling pattern was similar to the labeling pattern obtained with antitubulin, but anti-adligin labeled some granules in the gut that were not labeled with antitubulin. These results suggest that adligin may be part of the interphase microtubule network in C. elegans.

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