Chamblin C et al. (1992) Worm Breeder's Gazette "Sequence Analysis of Dominant and Recessive her-1 Mutations"

Trent C, Chamblin C

[Worm Breeder's Gazette, 1992]

Two her-1 transcripts have been previously identified: a 0.8 kb transcript found at high levels in XO and very low levels in XX animals and a 1.2 kb transcript observed at low levels in XO animals only. The dominant her-1 mutations n695 and y101 ,which cause variable masculinization of XX animals, result in increased levels of both her-1 transcripts in XX embryos. We have cloned and sequenced the her-1 genes from partial genomic libraries of these mutant strains. Both strains have a G --> A transition a few base pairs upstream of the cap site for the 1.2 kb transcript. That the two strains have the same mutation was not expected since y101 shows a more extreme sexual transformation than n695 .The mutation has been confirmed in both strains by direct sequencing of PCR products made from genomic DNA. We have sequenced the exons for each mutant gene and about l.5kb upstream of the transcription start site, but have not observed an additional mutation in either strain. We are in the process of sequencing the recessive her-1 alleles that result in the preferential loss of the 1.2kb transcript: ct50 n695 ,e1519 ,e1574 ,n827 n695 and y10 .In such strains, the 1.2kb transcript cannot be detected by Northern analysis, but the 0.8kb transcript is present at approximately wild-type levels. The ct50 n695 mutation, used originally to isolate her-1 sequences, results from a Tc1 insert 55 bp upstream of the cap site for the 1.2 kb transcript. We are analyzing the other four mutant alleles by direct sequencing of DNA generated by PCR amplification of specific regions of the her-1 gene. The loss of the larger transcript in e1519 is due to a splicing defect resulting from a G -->A transition mutation in the first base of intron #1. Work is still in progress on the other three alleles.

Perry MD et al. (1994) Genetics "Sequenced alleles of the Caenorhabditis elegans sex-determining gene her-1 include a novel class of conditional promoter mutations."

Perry MD, Chamblin C, Robertson B, Trent C, Wood WB

[Genetics, 1994]

In the control of Caenorhabditis elegans sex determination, the her-1 gene must normally be activated to allow male development of XO animals and deactivated to allow hermaphrodite development of XX animals. The gene is regulated at the transcriptional level and has two nested male-specific transcripts. The larger of these encodes a small, novel, cysteine-rich protein responsible for masculinizing activity. Of the 32 extant mutant alleles, 30 cause partial or complete loss of masculinizing function (lf), while 2 are gain-of-function (gf) alleles resulting in abnormal masculinization of XX animals. We have identified the DNA sequence changes in each of these 32 alleles. Most affect the protein coding functions of the gene, but six are in the promoter region, including the two gf mutations. These two mutations may define a binding site for negative regulators of her-1. Three of the four remaining promoter mutations are single base changes that cause, surprisingly, temperature-sensitive loss of her-1 function. Such conditional promoter mutations have previously not been found among either prokaryotic or eukaryotic mutants analyzed at the molecular level.

Perry MD et al. (1993) International C. elegans Meeting "her-1(tss) alleles in the P1 promoter: a novel mechanism of temperature sensitivity."

Robertson B, Wood WB, Trent C, Chamblin C, Perry MD

[International C. elegans Meeting, 1993]

Robertson B et al. (1993) International C. elegans Meeting "Mutations in the her-1 gene: Several cysteine replacements and some promoter lesions."

Robertson B, Perry MD, Chamblin C, Wood WB, Trent C

[International C. elegans Meeting, 1993]

Trent C et al. (1991) Mech Dev "Sex-specific transcriptional regulation of the C. elegans sex-determining gene her-1."

Wood WB, Trent C, Gavinski S, Chamblin C, Purnell B, Hageman JM

[Mech Dev, 1991]

Expression of the sex-determining gene her-1 is required in C. elegans for the normal male development of XO animals. Abnormal expression in XX animals, which normally develop as hermaphrodites, results in aberrant male development. We have isolated a molecular clone of the her-1 gene and have identified two transcripts that are present in XO animals at all stages of development: an abundant 0.8 kb transcript and a less abundant 1.2 kb transcript. In preparations of XX animals, the 0.8 kb transcript was observed only at very low levels in embryos or L1 larvae and the 1.2 kb transcript was not detected. Two gain-of-function her-1 mutations result in high levels of the 1.2 and 0.8 kb transcripts in XX animals. The levels of these transcripts are also elevated in XX animals carrying a loss-of-function mutation in either sdc-1 or sdc-2, consistent with the proposed roles of these genes as negative regulators of her-1. These results demonstrate that expression of the her-1 gene in males and hermaphrodites is controlled at the level of transcript synthesis or accumulation. This mode of regulation contrasts with that found for the Drosophila sex-determining genes, whose sex-specific expression is controlled by differential splicing in males and females.

Zhao Y et al. (2007) BMC Genomics "Poly-G/poly-C tracts in the genomes of Caenorhabditis."

Zhao Y, O'Neil NJ, Rose AM

[BMC Genomics, 2007]

ABSTRACT: BACKGROUND: In the genome of Caenorhabditis elegans, homopolymeric poly-G/poly-C tracts (G/C tracts) exist at high frequency and are maintained by the activity of the DOG-1 protein. The frequency and distribution of G/C tracts in the genomes of C. elegans and the related nematode, C. briggsae were analyzed to investigate possible biological roles for G/C tracts. RESULTS: In C. elegans, G/C tracts are distributed along every chromosome in a non-random pattern. Most G/C tracts are within introns or are close to genes. Analysis of SAGE data showed that G/C tracts correlate with the levels of regional gene expression in C. elegans. G/C tracts are over-represented and dispersed across all chromosomes in another Caenorhabditis species, C. briggase. However, the positions and distribution of G/C tracts in C. briggsae differ from those in C. elegans. Furthermore, the C. briggsae dog-1 ortholog CBG19723 can rescue the mutator phenotype of C. elegans dog-1 mutants. CONCLUSIONS: The abundance and genomic distribution of G/C tracts in C. elegans, the effect of G/C tracts on regional transcription levels, and the lack of positional conservation of G/C tracts in C. briggsae suggest a role for G/C tracts in chromatin structure but not in the transcriptional regulation of specific genes.

Bhagwati P Gupta et al. (2002) West Coast Worm Meeting "Genetic analysis of the vulval mutants in C. briggsae"

Shahla Gharib, Bhagwati P Gupta, Paul W Sternberg, Jennifer X Li

[West Coast Worm Meeting, 2002]

To understand the evolution of developmental mechanisms, we are doing a comparative analysis of vulval patterning in C. elegans and C. briggsae. C. briggsae is closely related to C. elegans and has identical looking vulval morphology. However, recent studies have indicated subtle differences in the underlying mechanisms of development. The recent completion of C. briggsae genome sequence by the C. elegans Sequencing Consortium is extremely valuable in identifying the conserved genes between C. elegans and C. briggsae.

Antika TR et al. (2023) J Biol Chem "Sequence-specific targeting of C. elegans C-Ala to the D-loop of tRNAAla."

Horng JC, Hsu HL, Nazilah KR, Wang CC, Wang TL, Wang SC, Antika TR, Chuang TH, Chrestella DJ, Wang SW, Tseng YK, Pan HC

[J Biol Chem, 2023]

Alanyl-tRNA synthetase (AlaRS) retains a conserved prototype structure throughout its biology. Nevertheless, its C-terminal domain (C-Ala) is highly diverged and has been shown to play a role in either tRNA or DNA binding. Interestingly, we discovered that Caenorhabditis elegans cytoplasmic C-Ala (Ce-C-Ala_c) robustly binds both ligands. How Ce-C-Ala_c targets its cognate tRNA and whether a similar feature is conserved in its mitochondrial counterpart remain elusive. We show that the N- and C-terminal subdomains of Ce-C-Ala_c are responsible for DNA and tRNA binding, respectively. Ce-C-Ala_c specifically recognized the conserved invariant base G¹⁸ in the D-loop of tRNA^Ala through a highly conserved lysine residue, K934. Despite bearing little resemblance to other C-Ala domains, C. elegans mitochondrial C-Ala (Ce-C-Ala_m) robustly bound both tRNA^Ala and DNA and maintained targeting specificity for the D-loop of its cognate tRNA. This study uncovers the underlying mechanism of how C. elegans C-Ala specifically targets the D-loop of tRNA^Ala.

Blumenthal TE et al. (1994) Worm Breeder's Gazette "C. elegans U2AF 65."

Zorio DAR, Lea K, Blumenthal TE

[Worm Breeder's Gazette, 1994]

C. elegans U2AF65

Oomura, S. et al. (2019) International Worm Meeting "Early embryogenesis of C. inopinata, a sibling species of C.elegans."

Matsumura, Y., Haruta, N., Hoshi, Y., Sugimoto, A., Oomura, S.

[International Worm Meeting, 2019]

C. inopinata is a newly discovered sibling species of C. elegans. Despite their phylogenetic closeness, they have many differences in morphology and ecology. For example, while C. elegans is hermaphroditic, C. inopinata is gonochoristic; C. inopinata is nearly twice as long as C. elegans. A comparative analysis of C. elegans and C. inopinata enables us to study how genomic changes cause these phenotypic differences. In this study, we focused on early embryogenesis of C. inopinata. First, by the microparticle bombardment method we made a C. inopinata line that express GFP::histone in whole body, and compared the early embryogenesis with C. elegans by DIC and fluorescent live imaging. We found that the position of pronuclei and polar bodies were different between these two species. In C. elegans, the female and male pronuclei first become visible in anterior and posterior sides, respectively, then they meet at the center of embryo. On the other hand, the initial position of pronuclei were more closely located in C. inopinata. Also, the polar bodies usually appear in the anterior side of embryo in C. elegans, but they appeared at random positions in C. inopinata. Therefore, we infer that C. inopinata may have a different polarity formation mechanism from that in C. elegans. We are also analyzing temperature dependency of embryogenesis in C. inopinata, whose optimal temperature is ~7 degree higher than that in C. elegans.