Genetic analysis of temperature-sensitive embryogenesis mutants in Caenorhabditis elegans

Abstract The Caenorhabditis elegans rol-3(e754) mutation is a member of a general class of mutations affecting gross morphology, presumably through disruption of the nematode cuticle. Adult worms homozygous for rol-3(e754) exhibit rotation about their long axis associated with a left-hand twisted cuticle, musculature, gut and ventral nerve cord. Our laboratory previously isolated 12 recessive lethal alleles of rol-3. All these lethal alleles cause an arrest in development at either early or mid-larval stages, suggesting that the rol-3 gene product performs an essential developmental function. Furthermore, through the use of the heterochronic mutants lin-14 and lin-29, we have established that the expression of rol-3(e754)'s adult specific visible function is not dependent on the presence of an adult cuticle. In an attempt to understand rol-3's developmental role we sought to identify other genes whose products interact with that of rol-3. Toward this end, we generated eight EMS induced and two gamma irradiation-induced recessive suppressors of the temperature sensitive (ts) mid-larval lethal phenotype of rol-3(s1040ts). These suppressors define two complementation groups srl-1 II and srl-2 III; and, while they suppress the rol-3(s1040) lethality, they do not suppress the adult specific visible rolling phenotype. Furthermore, there is a complex genetic interaction between srl-2 and srl-1 such that srl-2(s2506) fails to complement all srl alleles tested. These results suggest that srl-1 and srl-2 may share a common function and, thus, possibly constitute members of the same gene family. Mutations in both srl-1 and srl-2 produce no obvious hermaphrodite phenotypes in the absence of rol-3(s1040ts); however, males homozygous for either srl-1 or srl-2 display aberrant tail morphology. We present evidence suggesting that the members of srl-2 are not allele specific with respect to their suppression of rol-3 lethality, and that rol-3 may act in some way to influence proper posterior morphogenesis. Finally, based on our genetic analysis of rol-3 and the srl mutations, we present a model whereby the wild-type products of the srl loci act in a concerted manner to negatively regulate the rol-3 gene.

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Faculty Opinions recommendation of Genetic analysis of endocytosis in Caenorhabditis elegans: coelomocyte uptake defective mutants.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1000484.11509 ◽

2001 ◽

Author(s):

Robert K Herman

Keyword(s):

Caenorhabditis Elegans ◽

Genetic Analysis

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Faculty Opinions recommendation of A reverse genetic analysis of components of the Toll signaling pathway in Caenorhabditis elegans.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1002561.28554 ◽

2001 ◽

Author(s):

Jonathan Hodgkin

Keyword(s):

Caenorhabditis Elegans ◽

Genetic Analysis ◽

Signaling Pathway ◽

Reverse Genetic ◽

Toll Signaling

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Genetic analysis of temperature-sensitive lethal mutants of Salmonella typhimurium.

Genetics ◽

10.1093/genetics/123.4.625 ◽

1989 ◽

Vol 123 (4) ◽

pp. 625-633 ◽

Cited By ~ 1

Author(s):

M B Schmid ◽

N Kapur ◽

D R Isaacson ◽

P Lindroos ◽

C Sharpe

Keyword(s):

High Temperature ◽

Genetic Analysis ◽

Salmonella Typhimurium ◽

Complex Medium ◽

Temperature Sensitive ◽

Nonpermissive Temperature ◽

Anaerobic Conditions ◽

Temperature Growth ◽

Lethal Phenotype ◽

Lethal Mutations

Abstract We have isolated 440 mutants of Salmonella typhimurium that show temperature-sensitive growth on complex medium at 44 degrees. Approximately 16% of the mutations in these strains have been mapped to 17 chromosomal locations; two of these chromosomal locations seem to include several essential genes. Genetic analysis of the mutations suggests that the collection saturates the genes readily mutable to a ts lethal phenotype in S. typhimurium. Physiological characteristics of the ts lethal mutants were tested: 6% of the mutants can grow at high temperature under anaerobic conditions, 17% can grow when the medium includes 0.5 M KCl, and 9% of the mutants die after a 2-hr incubation at the nonpermissive temperature. Most ts lethal mutations in this collection probably affect genes required for growth at all temperatures (not merely during high temperature growth) since Tn10 insertions that cause a temperature-sensitive lethal phenotype are rare.

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THE SELECTION OF S. CEREVISIAE MUTANTS DEFECTIVE IN THE START EVENT OF CELL DIVISION

Genetics ◽

10.1093/genetics/95.3.561 ◽

1980 ◽

Vol 95 (3) ◽

pp. 561-577 ◽

Cited By ~ 4

Author(s):

Steven I Reed

Keyword(s):

Cell Division ◽

Genetic Analysis ◽

Linkage Map ◽

Nuclear Genes ◽

Temperature Sensitive ◽

Restrictive Temperature ◽

Mating Pheromone ◽

Preliminary Characterization ◽

Complementation Groups ◽

Selection Of

ABSTRACT Thirty-three temperature-sensitive mutations defective in the start event of the cell division cycle of Saccharomyces cereuisiae were isolated and subjected to preliminary characterization. Complementation studies assigned these mutations to four complementation groups, one of which, cdc28, has been described previously. Genetic analysis revealed that these complementation groups define single nuclear genes, unlinked to one another. One of the three newly identified genes, cdc37, has been located in the yeast linkage map on chromosome IV, two meiotic map units distal to hom2.—Each mutation produces stage-specific arrest of cell division at start, the same point where mating pheromone interrupts division. After synchronization at start by incubation at the restrictive temperature, the mutants retain the capacity to enlarge and to conjugate.

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Two Pleiotropic Classes of daf-2 Mutation Affect Larval Arrest, Adult Behavior, Reproduction and Longevity in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/150.1.129 ◽

1998 ◽

Vol 150 (1) ◽

pp. 129-155 ◽

Cited By ~ 23

Author(s):

David Gems ◽

Amy J Sutton ◽

Mark L Sundermeyer ◽

Patrice S Albert ◽

Kevin V King ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Adult Longevity ◽

Temperature Sensitive ◽

Adult Behavior ◽

Dauer Larva ◽

Class 1 ◽

Low Levels ◽

Dauer Larvae ◽

Overlapping Classes ◽

Receptor Family

Abstract The nematode Caenorhabditis elegans responds to overcrowding and scarcity of food by arresting development as a dauer larva, a nonfeeding, long-lived, stress-resistant, alternative third-larval stage. Previous work has shown that mutations in the genes daf-2 (encoding a member of the insulin receptor family) and age-1 (encoding a PI 3-kinase) result in constitutive formation of dauer larvae (Daf-c), increased adult longevity (Age), and increased intrinsic thermotolerance (Itt). Some daf-2 mutants have additional developmental, behavioral, and reproductive defects. We have characterized in detail 15 temperature-sensitive and 1 nonconditional daf-2 allele to investigate the extent of daf-2 mutant defects and to examine whether specific mutant traits correlate with each other. The greatest longevity seen in daf-2 mutant adults was approximately three times that of wild type. The temperature-sensitive daf-2 mutants fell into two overlapping classes, including eight class 1 mutants, which are Daf-c, Age, and Itt, and exhibit low levels of L1 arrest at 25.5°. Seven class 2 mutants also exhibit the class 1 defects as well as some or all of the following: reduced adult motility, abnormal adult body and gonad morphology, high levels of embryonic and L1 arrest, production of progeny late in life, and reduced brood size. The strengths of the Daf-c, Age, and Itt phenotypes largely correlated with each other but not with the strength of class 2-specific defects. This suggests that the DAF-2 receptor is bifunctional. Examination of the null phenotype revealed a maternally rescued egg, L1 lethal component, and a nonconditional Daf-c component. With respect to the Daf-c phenotype, the dauer-defective (Daf-d) mutation daf-12(m20) was epistatic to daf-2 class 1 alleles but not the severe class 2 alleles tested. All daf-2 mutant defects were suppressed by the daf-d mutation daf-16(m26). Our findings suggest a new model for daf-2, age-1, daf-12, and daf-16 interactions.

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THE GENETIC ANALYSIS OF A RECIPROCAL TRANSLOCATION, eT1(III; V), IN CAENORHABDITIS ELEGANS

Genetics ◽

10.1093/genetics/99.3-4.415 ◽

1981 ◽

Vol 99 (3-4) ◽

pp. 415-428

Author(s):

Raja E Rosenbluth ◽

David L Baillie

Keyword(s):

Caenorhabditis Elegans ◽

Genetic Analysis ◽

Gene Order ◽

Reciprocal Translocation ◽

New Order ◽

Linkage Groups ◽

Recombination Rates ◽

Left Half ◽

New Gene ◽

The Right

ABSTRACT The Caenorhabditis elegans mutation e873, which results in a recessive uncoordinated phenotype (formerly named Unc-72) and which had been isolated after 32P t reatment (BRENNER1 974), has now been found to act as a crossover suppressor and to be associated with a translocation between linkage groups (LG's) IIIand V. The translocation has been named, eTl(ZI1; V); eT1acts as a dominant crossover suppressor for both the right half of LGIIIand the left half of LGV,providing a balancer for a total of 39 map units. The uncoordinated e873phenotype has been shown to be a consequence of Eminactive unr- 36111gene. It was possible to demonstrate that, in translocation heterozygotes, eT1chromosomes marked with either sma-3or dpy-11segregate from normal LGIII,while those marked with bli-5, sm-2or unc-42segregate from normal LGV.Since bli-5and sma-2are normally on LGIII,and dpy-11is normally on LGV,it is concluded that: (a) eT1is a reciprocal translocation; (b) there is a breakpoint between sma-3and sma-2in LGIII(the region containing unc- 36)and one between dpy-11and unc-42in LGV;(c) thera is no dominant centromere between sma-2and bli-5on LGIII,since in eT1these genes are not linked to a LGIIIcentromere. Similarly, it is highly unlikely that there is a centromere to the left of dpy-11on LGV.The new gene order in eT1was determined by measuring recombination rates between markers in eT1homozygotes. It is concluded that the new order is: dpy-1 sma-3 (break) dpy-11 unc-60,and bli-5 sma-2 (break) unc-42 unc-51.——Thisis the first analysis of a C. eleganstranslocation with respect to reciprocity, breakpoints and new gene order.

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