A Screen for Genetic Loci Required for Hypodermal Cell and Glial-Like Cell Development During Caenorhabditis elegans Embryogenesis

The Caenorhabditis elegans lin-26 gene is expressed in all nonneuronal ectodermal cells. To identify genes required to specify the fates of ectodermal cells, we have conducted screens designed to identify loci whose zygotic function would be required for normal lin-26 expression. First, we examined 90 deficiencies covering 75% of the genome; second, we examined the progeny of 3600 genomes after EMS mutagenesis. We identified six loci that appear to be required for normal lin-26 expression. We argue that the deficiency eDf19 deletes a gene involved in specifying hypodermal cell fates. The genes emb-29 (previously known) and ale-1 (newly found) could be involved in a cell cycle function and/or in specifylng the fates of some precursors within different lineages that generate hypodermal cells and nonectodermal cells. We argue that the overlapping deficiencies qDf7, qDf8 and qDf9 delete a gene required to limit the number of nonneuronal ectodermal cells. We suggest that the deficiencies ozDf2, itDf2 and nDf42 delete genes required, directly or indirectly, to repress lin-26 expression in cells that normally do not express lin-26. We discuss the implications of these findings concerning the generation of the ectoderm.

Download Full-text

The 110-kD spindle pole body component of Saccharomyces cerevisiae is a phosphoprotein that is modified in a cell cycle-dependent manner.

The Journal of Cell Biology ◽

10.1083/jcb.132.5.903 ◽

1996 ◽

Vol 132 (5) ◽

pp. 903-914 ◽

Cited By ~ 30

Author(s):

D B Friedman ◽

H A Sundberg ◽

E Y Huang ◽

T N Davis

Keyword(s):

Cell Cycle ◽

Mitotic Spindle ◽

Spindle Pole Body ◽

Spindle Pole ◽

Wild Type ◽

Spindle Formation ◽

Pole Body ◽

A Cell ◽

In Cells

Spc110p (Nuf1p) is an essential component of the yeast microtubule organizing center, or spindle pole body (SPB). Asynchronous wild-type cultures contain two electrophoretically distinct isoforms of Spc110p as detected by Western blot analysis, suggesting that Spc110p is modified in vivo. Both isoforms incorporate 32Pi in vivo, suggesting that Spc110p is post-translationally modified by phosphorylation. The slower-migrating 120-kD Spc110p isoform after incubation is converted to the faster-migrating 112-kD isoform after incubation with protein phosphatase PP2A, and specific PP2A inhibitors block this conversion. Thus, additional phosphorylation of Spc110p at serine and/or threonine residues gives rise to the slower-migrating 120-kD isoform. The 120-kD isoform predominates in cells arrested in mitosis by the addition of nocodazole. However, the 120-kD isoform is not detectable in cells grown to stationary phase (G0) or in cells arrested in G1 by the addition of alpha-factor. Temperature-sensitive cell division cycle (cdc) mutations demonstrate that the presence of the 120-kD isoform correlates with mitotic spindle formation but not with SPB duplication. In a synchronous wild-type population, the additional serine/threonine phosphorylation that gives rise to the 120-kD isoform appears as cells are forming the mitotic spindle and diminishes as cells enter anaphase. None of several sequences similar to the consensus for phosphorylation by the Cdc28p (cdc2p34) kinase is important for these mitosis-specific phosphorylations or for function. Carboxy-terminal Spc110p truncations lacking the calmodulin binding site can support growth and are also phosphorylated in a cell cycle-specific manner. Further truncation of the Spc110p carboxy terminus results in mutant proteins that are unable to support growth and now migrate as single species. Collectively, these results provide the first evidence of a structural component of the SPB that is phosphorylated during spindle formation and dephosphorylated as cells enter anaphase.

Download Full-text

Mitochondrial adenosine triphosphatase of the fission yeast, Schizosaccharomyces pombe 972h−. Changes in activity and oligomycin-sensitivity during the cell cycle of catabolite-repressed and -de-repressed cells

Biochemical Journal ◽

10.1042/bj1620039 ◽

1977 ◽

Vol 162 (1) ◽

pp. 39-46 ◽

Cited By ~ 6

Author(s):

S W Edwards ◽

D Lloyd

Keyword(s):

Cell Cycle ◽

Atpase Activity ◽

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Adenosine Triphosphatase ◽

Total Activity ◽

Stages Of Growth ◽

Synchronous Cultures ◽

A Cell ◽

In Cells

1. Changes in activity of ATPase (adenosine triphosphatase) during the cell cycle of Schizosaccharomyces pombe were analysed in cell-free extracts of cells harvested from different stages of growth of synchronous cultures and also after cell-cycle fractionation. 2. Oligomycin-sensitive ATPase oscillates in both glucose-repressed synchronous cultures and shows four maxima of activity approximately equally spaced through the cell cycle. The amplitude of the oscillations accounts for between 13 and 80% of the total activity at different times in the cell cycle. 3. Oligomycin sensitivity varies over a fourfold range at different stages of the cell cycle. 4. The periodicity of maximum oligomycin sensitivity is one-quarter of a cell cycle. 5. These results were confirmed for the first three-quarters of the cell cycle by cell-cycle fractionation. 6. In cells growing synchronously with glycerol, ATPase activity increases in a stepwise pattern, with two steps per cell cycle; the first of these occurs at 0.54 of the cell cycle and the second at 0.95. 7. These results are discussed in relation to previously obtained data on the development of mitochondrial activities during the cell cycle.

Download Full-text

Cell cycle-dependent sequencing of cell fate decisions in Caenorhabditis elegans vulva precursor cells

Development ◽

10.1242/dev.126.9.1947 ◽

1999 ◽

Vol 126 (9) ◽

pp. 1947-1956 ◽

Cited By ~ 5

Author(s):

V. Ambros

Keyword(s):

Cell Cycle ◽

Caenorhabditis Elegans ◽

Cell Fate ◽

Precursor Cells ◽

S Phase ◽

Cycle Phase ◽

Cell Fates ◽

Cell Fate Decisions ◽

Cycle Arrest ◽

Cycle Dependent

In Caenorhabditis elegans, the fates of the six multipotent vulva precursor cells (VPCs) are specified by extracellular signals. One VPC expresses the primary (1 degrees) fate in response to a Ras-mediated inductive signal from the gonad. The two VPCs flanking the 1 degrees cell each express secondary (2 degrees) fates in response to lin-12-mediated lateral signaling. The remaining three VPCs each adopt the non-vulval tertiary (3 degrees) fate. Here I describe experiments examining how the selection of these vulval fates is affected by cell cycle arrest and cell cycle-restricted lin-12 activity. The results suggest that lin-12 participates in two developmental decisions separable by cell cycle phase: lin-12 must act prior to the end of VPC S phase to influence a 1 degrees versus 2 degrees cell fate choice, but must act after VPC S phase to influence a 3 degrees versus 2 degrees cell fate choice. Coupling developmental decisions to cell cycle transitions may provide a mechanism for prioritizing or ordering choices of cell fates for multipotential cells.

Download Full-text

Distinct Developmental Function of Two Caenorhabditis elegans Homologs of the Cohesin Subunit Scc1/Rad21

Molecular Biology of the Cell ◽

10.1091/mbc.e02-09-0603 ◽

2003 ◽

Vol 14 (6) ◽

pp. 2399-2409 ◽

Cited By ~ 21

Author(s):

Yoshiko Mito ◽

Asako Sugimoto ◽

Masayuki Yamamoto

Keyword(s):

Cell Cycle ◽

Caenorhabditis Elegans ◽

Chromosome Segregation ◽

Mitotic Chromosome ◽

Dependent Manner ◽

C Elegans ◽

Late Embryogenesis ◽

A Cell ◽

Cohesin Subunit ◽

Cycle Dependent

Cohesin, which mediates sister chromatid cohesion, is composed of four subunits, named Scc1/Rad21, Scc3, Smc1, and Smc3 in yeast. Caenorhabditis elegans has a single homolog for each of Scc3, Smc1, and Smc3, but as many as four for Scc1/Rad21 (COH-1, SCC-1/COH-2, COH-3, and REC-8). Except for REC-8 required for meiosis, function of these C. elegans proteins remains largely unknown. Herein, we examined their possible involvement in mitosis and development. Embryos depleted of the homolog of either Scc3, or Smc1, or Smc3 by RNA interference revealed a defect in mitotic chromosome segregation but not in chromosome condensation and cytokinesis. Depletion of SCC-1/COH-2 caused similar phenotypes. SCC-1/COH-2 was present in cells destined to divide. It localized to chromosomes in a cell cycle-dependent manner. Worms depleted of COH-1 arrested at either the late embryonic or the larval stage, with no indication of mitotic dysfunction. COH-1 associated chromosomes throughout the cell cycle in all somatic cells undergoing late embryogenesis or larval development. Thus, SCC-1/COH-2 and the homologs of Scc3, Smc1, and Smc3 facilitate mitotic chromosome segregation during the development, presumably by forming a cohesin complex, whereas COH-1 seems to play a role important for development but unrelated to mitosis.

Download Full-text