scholarly journals Identification of grandchildless loci whose products are required for normal germ-line development in the nematode Caenorhabditis elegans.

Genetics ◽  
1991 ◽  
Vol 129 (4) ◽  
pp. 1061-1072 ◽  
Author(s):  
E E Capowski ◽  
P Martin ◽  
C Garvin ◽  
S Strome
Keyword(s):  
Drosophila Melanogaster ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Structural Integrity ◽  
Germ Line ◽  
Phenotypic Characterization ◽  
Nematode Caenorhabditis Elegans ◽  
Homozygous Mutant ◽  
Germ Granules

Abstract To identify genes that encode maternal components required for development of the germ line in the nematode Caenorhabditis elegans, we have screened for mutations that confer a maternal-effect sterile or "grandchildless" phenotype: homozygous mutant hermaphrodites produced by heterozygous mothers are themselves fertile, but produce sterile progeny. Our screens have identified six loci, defined by 21 mutations. This paper presents genetic and phenotypic characterization of four of the loci. The majority of mutations, those in mes-2, mes-3 and mes-4, affect postembryonic germ-line development; the progeny of mutant mothers undergo apparently normal embryogenesis but develop into agametic adults with 10-1000-fold reductions in number of germ cells. In contrast, mutations in mes-1 cause defects in cytoplasmic partitioning during embryogenesis, and the resulting larvae lack germ-line progenitor cells. Mutations in all of the mes loci primarily affect the germ line, and none disrupt the structural integrity of germ granules. This is in contrast to grandchildless mutations in Drosophila melanogaster, all of which disrupt germ granules and affect abdominal as well as germ-line development.

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.

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.

Viable maternal-effect mutations that affect the development of the nematode Caenorhabditis elegans.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1351-1364 ◽  
Author(s):  
S Hekimi ◽  
P Boutis ◽  
B Lakowski
Keyword(s):  
Quantitative Analysis ◽  
Caenorhabditis Elegans ◽  
Maternal Effect ◽  
Genetic Screen ◽  
Phenotypic Characterization ◽  
Nematode Caenorhabditis Elegans ◽  
Critical Function ◽  
Complementation Groups

Abstract We carried out a genetic screen for viable maternal-effect mutants to identify genes with a critical function relatively early in development. This type of mutation would not have been identified readily in previous screens for viable mutants and therefore could define previously unidentified genes. We screened 30,000 genomes and identified 41 mutations falling into 24 complementation groups. We genetically mapped these 24 loci; only two of them appear to correspond to previously identified genes. We present a partial phenotypic characterization of the mutants and a quantitative analysis of the degree to which they can be maternally or zygotically rescued.

scholarly journals fog-2, a germ-line-specific sex determination gene required for hermaphrodite spermatogenesis in Caenorhabditis elegans.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 43-61 ◽  
Author(s):  
T Schedl ◽  
J Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
Germ Line ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Wild Type ◽  
Negative Regulators ◽  
Nematode Caenorhabditis Elegans ◽  
Isolation And Characterization

Abstract This paper describes the isolation and characterization of 16 mutations in the germ-line sex determination gene fog-2 (fog for feminization of the germ line). In the nematode Caenorhabditis elegans there are normally two sexes, self-fertilizing hermaphrodites (XX) and males (XO). Wild-type XX animals are hermaphrodite in the germ line (spermatogenesis followed by oogenesis), and female in the soma. fog-2 loss-of-function mutations transform XX animals into females while XO animals are unaffected. Thus, wild-type fog-2 is necessary for spermatogenesis in hermaphrodites but not males. The fem genes and fog-1 are each essential for specification of spermatogenesis in both XX and XO animals. fog-2 acts as a positive regulator of the fem genes and fog-1. The tra-2 and tra-3 genes act as negative regulators of the fem genes and fog-1 to allow oogenesis. Two models are discussed for how fog-2 might positively regulate the fem genes and fog-1 to permit spermatogenesis; fog-2 may act as a negative regulator of tra-2 and tra-3, or fog-2 may act positively on the fem genes and fog-1 rendering them insensitive to the negative action of tra-2 and tra-3.

scholarly journals The Caenorhabditis elegans Sex Determination Gene mog-1 Encodes a Member of the DEAH-Box Protein Family

1999 ◽  
Vol 19 (3) ◽  
pp. 2189-2197 ◽  
Author(s):  
Alessandro Puoti ◽  
Judith Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Line ◽  
Regulatory Element ◽  
Residual Activity ◽  
Normal Growth ◽  
Null Alleles ◽  
Phenotypic Characterization ◽  
Rna Regulation ◽  
And Control

ABSTRACT In the Caenorhabditis elegans hermaphrodite germ line, the sex-determining gene fem-3 is repressed posttranscriptionally to arrest spermatogenesis and permit oogenesis. This repression requires a cis-acting regulatory element in the fem-3 3′ untranslated region; the FBF protein, which binds to this element; and at least six mog genes. In this paper, we report the molecular characterization of mog-1 as well as additional phenotypic characterization of this gene. Themog-1 gene encodes a member of the DEAH-box family. Threemog-1 alleles possess premature stop codons and are likely to be null alleles, and one is a missense mutation and is likely to retain residual activity. mog-1 mRNA is expressed in both germ line and somatic tissues and appears to be ubiquitous. The MOG-1 DEAH-box protein is most closely related to proteins essential for splicing in the yeast Saccharomyces cerevisiae, but splicing appears to occur normally in a mog-1-null mutant. In addition to its involvement in the sperm-oocyte switch and control of fem-3, zygotic mog-1 is required for robust germ line proliferation and for normal growth during development. We suggest that mog-1 plays a broader role in RNA regulation than previously considered.

Characterization of a germ-line proliferation mutation in C. elegans

Development ◽  
1992 ◽  
Vol 116 (3) ◽  
pp. 755-766 ◽  
Author(s):  
M.J. Beanan ◽  
S. Strome
Keyword(s):  
Cell Cycle ◽  
Germ Cells ◽  
Germ Line ◽  
Mitotic Cell ◽  
Phenotypic Characterization ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
C Elegans ◽  
Large Populations

The C. elegans germ line is generated by extensive proliferation of the two germ-line progenitor cells present in newly hatched larvae. We describe genetic and phenotypic characterization of glp-4, a locus whose product is required for normal proliferation of the germ line. glp-4(bn2ts) mutant worms raised at the restrictive temperature contain approximately 12 germ nuclei, in contrast to the 700–1000 present in wild-type adults. The few germ cells present in sterile glp-4 adults appear to be arrested at prophase of the mitotic cell cycle. This cell-cycle disruption prevents the germ cells from entering meiosis and differentiating into gametes. Shifting sterile glp-4 worms to the permissive temperature enables their germ cells to undergo extensive proliferation and form gametes, demonstrating that the bn2-induced cell-cycle arrest is reversible and that proliferation and differentiation of germ cells can be uncoupled from development of the somatic gonad. The glp-4(bn2ts) mutation can be used to generate large populations of worms that are severely depleted in germ cells, facilitating determination of whether any gene of interest is expressed in the germ line or soma or both.

scholarly journals Genetic and Molecular Characterization of sting, a Gene Involved in Crystal Formation and Meiotic Drive in the Male Germ Line of Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 749-760 ◽  
Author(s):  
Armin Schmidt ◽  
Gioacchino Palumbo ◽  
Maria P Bozzetti ◽  
Patrizia Tritto ◽  
Sergio Pimpinelli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Drosophila Melanogaster ◽  
Null Allele ◽  
Germ Line ◽  
Meiotic Drive ◽  
P Element ◽  
Crystal Formation ◽  
Male Sterile ◽  
Male Sterile Mutation

Abstract The sting mutation, caused by a P element inserted into polytene region 32D, was isolated by a screen for male sterile insertions in Drosophila melanogaster. This sterility is correlated with the presence of crystals in spermatocytes and spermatids that are structurally indistinguishable from those produced in males carrying a deficiency of the Y-linked crystal (cry) locus. In addition, their morphology is needle-like in Ste+ flies and star-shaped in Ste flies, once again as observed in cry– males. The sti mutation leads to meiotic drive of the sex chromosomes, and the strength of the phenomenon is correlated with the copy number of the repetitive Ste locus. The same correlation is also true for the penetrance of the male sterile mutation. A presumptive sti null allele results in male sterility and lethal maternal effect. The gene was cloned and shown to code for a putative protein that is 866 amino acids long. A C-terminal domain of 82 amino acids is identified that is well conserved in proteins from different organisms. The gene is expressed only in the germline of both sexes. The interaction of sting with the Ste locus can also be demonstrated at the molecular level. While an unprocessed 8-kb Ste primary transcript is expressed in wild-type males, in X/Y homozygous sti males, as in X/Y cry– males, a 0.7-kb mRNA is produced.

Major sex-determining genes and the control of sexual dimorphism in Caenorhabditis elegans

Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 625-637 ◽  
Author(s):  
Jonathan Hodgkin ◽  
Andrew D. Chisholm ◽  
Michael M. Shen
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
X Chromosome ◽  
Germ Line ◽  
Cell Lineage ◽  
Regulatory Genes ◽  
Nematode Caenorhabditis Elegans ◽  
X Chromosomes ◽  
The Many ◽  
Lineage Analysis

Sex determination in Caenorhabditis elegans involves a cascade of major regulatory genes connecting the primary sex determining signal, X chromosome dosage, to key switch genes, which in turn direct development along either male or female pathways. Animals with one X chromosome (XO) are male, while animals with two X chromosomes (XX) are hermaphrodite: hermaphrodite development occurs because the action of the regulatory genes is modified in the germ line so that both sperm and oocytes are made inside a completely female soma. The regulatory genes are being examined by both genetic and molecular means. We discuss how these major genes, in particular the last switch gene in the cascade, tra-1, might regulate the many different sex-specific events that occur during the development of the hermaphrodite and of the male.Key words: nematode, Caenorhabditis elegans, sex determination, sexual differentiation, cell lineage analysis.

Sex determination in the germ line of Drosophila melanogaster: activation of the gene Sex-lethal

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 813-816 ◽  
Author(s):  
B. Granadino ◽  
P. Santamaria ◽  
L. Sanchez
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cells ◽  
Germ Line ◽  
Wild Type ◽  
Female Development ◽  
Pole Cell ◽  
Somatic Tissues ◽  
Wild Type Female ◽  
Sex Lethal ◽  
Pole Cell Transplantation

The germ line exhibits sexual dimorphism as do the somatic tissues. Cells with the 2X;2A chromosome constitution will follow the oogenic pathway and X;2A cells will develop into sperm. In both somatic and germ-line tissues, the sexual pathway chosen by the cells depends on the gene Sex-lethal (Sxl), whose function is continuously needed for female development. In the soma, the sex of the cells is autonomously determined by the X:A signal while, in the germ line, the sex is determined by cell autonomous (the X:A signal) and somatic inductive signals. Three X-linked genes have been identified, scute (sc), sisterless-a (sis-a) and runt (run), that determine the initial functional state of Sxl in the soma. Using pole cell transplantation, we have tested whether these genes are also needed to activate Sxl in the germ line. We found that germ cells simultaneously heterozygous for sc, sis-a, run and a deficiency for Sxl transplanted into wild-type female hosts develop into functional oocytes. We conclude that the genes sc, sis-a and run needed to activate Sxl in the soma seem not to be required to activate this gene in the germ line; therefore, the X:A signal would be made up by different genes in somatic and germ-line tissues. The Sxlf7M1/Sxlfc females do not have developed ovaries. We have shown that germ cells of this genotype transplanted into wild-type female hosts produce functional oocytes. We conclude that the somatic component of the gonads in Sxlf7M1/Sxlfc females is affected, and consequently germ cells do not develop.(ABSTRACT TRUNCATED AT 250 WORDS)

Zygotic expression of the pebble locus is required for cytokinesis during the postblastoderm mitoses of Drosophila

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 165-171 ◽  
Author(s):  
G. Hime ◽  
R. Saint
Keyword(s):  
Drosophila Melanogaster ◽  
Developmental Regulation ◽  
Single Cells ◽  
Embryonic Cell ◽  
Cell Cycles ◽  
Drosophila Embryogenesis ◽  
Zygotic Transcription ◽  
Homozygous Mutant ◽  
Mitotic Figures

Mutations at the pebble locus of Drosophila melanogaster result in embryonic lethality. Examination of homozygous mutant embryos at the end of embryogenesis revealed the presence of fewer and larger cells which contained enlarged nuclei. Characterization of the embryonic cell cycles using DAPI, propidium iodide, anti-tubulin and anti-spectrin staining showed that the first thirteen rapid syncytial nuclear divisions proceeded normally in pebble mutant embryos. Following cellularization, the postblastoderm nuclear divisions occurred (mitoses 14, 15 and 16), but cytokinesis was never observed. Multinucleate cells and duplicate mitotic figures were seen within single cells at the time of the cycle 15 mitoses. We conclude that zygotic expression of the pebble gene is required for cytokinesis following cellularization during Drosophila embryogenesis. We postulate that developmental regulation of zygotic transcription of the pebble gene is a consequence of the transition from syncytial to cellular mitoses during cycle 14 of embryogenesis.

Sign in / Sign up

Export Citation Format

Share Document