Rosenbluth RE et al. (1985) Genetics "Mutagenesis in Caenorhabditis elegans. II. A spectrum of mutational events induced with 1500 r of gamma-radiation."

Rosenbluth RE, Baillie DL, Cuddeford C

[Genetics, 1985]

We previously established a gamma-ray dose-response curve for recessive lethal events (lethals) captured over the eT1 balancer. In this paper we analyze the nature of lethal events produced, with a frequency of 0.04 per eT1 region, at a dose of 1500 r. To do so, we developed a protocol that, in the absence of cytogenetics, allows balanced lethals to be analyzed for associated chromosomal rearrangements. A set of 35 lethal strains was chosen for the analysis. Although the dosage was relatively low, a large number of multiple-break events were observed. The fraction of lethals associated with rearrangements was found to be 0.76. Currently most X- and gamma-ray dosages used for mutagenesis in C. elegans are 6000- 8000 r. From our data we conservatively estimated that 43% of rearrangements induced with 8000 r would be accompanied by additional chromosome breaks in the genome. With 1500 r the value was 5%. The 35 lethals studied were derived from 875 screened F1's. Among these lethals there were (1) at least two unc-36 duplications, (2) at least four translocations, (3) at least six deficiencies of chromosome V (these delete about 90% of the unc-60 to unc-42 region) and (4) several unanalyzed rearrangements. Thus, it is possible to recover desired rearrangements at reasonable rates with a dose of only 1500 r. We suggest that the levels of ionizing radiation employed in most published C. elegans studies are excessive and efforts should be made to use reduced levels

Rosenbluth RE et al. (1983) Mutat Res "Mutagenesis in Caenorhabditis elegans. I. A rapid eukaryotic mutagen test system using the reciprocal translocation eT1(III;V)."

Baillie DL, Cuddeford C, Rosenbluth RE

[Mutat Res, 1983]

The advantages of developing mutagenicity tests using the nematode, Caenorhabditis elegans, are discussed and an efficient in vivo test for detecting heritable autosomal recessive lethals over 40 map units is described. The test uses the reciprocal translocation, eT1(III;V), as a balancer. Dose-response curves for EMS (0.004-0.06 M) and gamma-radiation (500-3000 R) were obtained. The spontaneous induction frequency for lethal mutations in 40 map units was found to be 0.06%. Mutations could be detected within 10 days and confirmed within another 5 days. From the point of view of C. elegans genetics, the EMS and gamma-ray curves demonstrate that eT1 can be used to test the efficacy of a particular mutagen in this organism. Although the present eT1 protocol simultaneously screens hermaphrodite oocyte and sperm chromosomes, variations of the protocol that screen oocyte and sperm

Rosenbluth RE et al. (1982) Worm Breeder's Gazette "EMS and gamma-ray induction of recessive lethals in C elegans."

Baillie DL, Rosenbluth RE, Cuddeford C

[Worm Breeder's Gazette, 1982]

Previously (Genetics 99:415-428,1981; Newsletter Jan.1982) we had described a screening procedure for recessive lethal mutations in the region balanced by the reciprocal translocation, eT1(III,V), - a total of 40 map units. We have now finished collecting dose-response data for EMS and gamma-ray induction (except for one more experiment at 500R), and are in the process of analyzing some of the retained lethal strains. [See Figure 1] The screen detects heterozygous eT1 F1 hermaphrodites carrying at least 1 lethal on the normal homologues anywhere in the balanced region. This region consists of 2 parts: 21 map units between sma-2 and unc-64(III) and 18 map units between unc-60 and dpy-11(V). The screening procedure itself does not indicate in which of these 2 regions a particular heterozygote carries a lethal mutation, nor does it indicate whether there is more than one mutation present. We are therefore outcrossing the lethals and mapping the mutations to either LGIII or LGV (or to both). The first ones to be mapped are those obtained with 0.025M EMS and 1500R gamma-radiation respectively. Column 2 of the table shows the frequency of fertile screened F1's that had carried at least one lethal within the 40mu. screened. So far 38 EMS and 19 gamma-ray strains have been analyzed. [See Figure 2] Columns 4 and 5 show the number of strains in which only one of the 2 balanced regions carries any lethals, while column 6 shows the number carrying at least one lethal in both regions. Although the sample sizes are still small, the data show an interesting trend. If one assumes that the induction of recessive lethal mutations at a given mutagen dose follows a Poisson distribution, then column 7 shows the predicted fraction of lethal strains carrying more than one mutation in the balanced 40 map units ( regardless of whether they are all on III or V, or on both). Column 8 shows the actual minimum fraction of strains that carry at least 2 mutations (N.B. a strain carrying 2 mutations on say III would be scored as 'only on III'). In the case of 0.025M EMS this fraction is 0.053 and is consistent with a Poissonian distribution of EMS mutations. On the other hand, 1500R gamma-radiation appears to produce far more lethals on both III and V than predicted frequency of only 0.045 F1's carrying lethals one would expect most of these to be due to single-hit events). If this trend is confirmed by additional data, it may mean that many single-hit events are not detected as lethals and would be similar to results obtained by Lefevre for Drosophila (Genetics 99:461-480,1981). Lefevre analyzed lethals induced in mature sperm by an X-ray dose of 2000r, which gave 7% X-linked recessives. Of these 43% showed cytollogical rearrangements. We might, therefore, expect a large number of our gamma-ray lethals to be associated with rearrangements involving III and another chromosome, or V and another chromosome. What is not necessarily expected is that so many should affect both III and V, - unless there are many rearrangements induced by this dosage that involve more than 2 chromosomes. If a relatively large number of gamma-ray induced single-hit events are not detected as lethals, the apparent lag in our gamma-ray dose- response curve would be explained. What would still be puzzling is the fact that our curve differs from the linear dose-response curves found for X-ray induced sex-linked lethals in Drosophila sperm. Although our data are still scant and more are needed to clarify the gamma-ray lethals, we do want to emphasize that mutants obtained with doses as low as 1500R probably carry a number of breaks in their genomes. Future experiments include: 1. Analyzing the gamma-ray lethal strains for, (a) rearrangements ( b) deficiencies. 2 Determining the distribution of lets along the arms of III and V. 3. Comparing the relative sensitivities of hermaphrodite oocytes and male sperm to mutagens.

Rosenbluth RE et al. (1983) International C. elegans Meeting "EMS and gamma-ray mutagenesis in C elegans."

Rosenbluth RE, Baillie DL, Scott G, Cuddeford C

[International C. elegans Meeting, 1983]

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.

Guven K (1995) Journal of Thermal Biology "Differential expression of hsp70 proteins in response to heat and cadmium in Caenorhabditis elegans."

Guven K

[Journal of Thermal Biology, 1995]

1. The patterns of HSP70 expression induced in Caenorhabditis elegans by mild (31 degrees C) or severe (34 degrees C) heat shock, and by cadmium ions at 31 degrees C, have been compared with those expressed constitutively ill 20 degrees C controls by 1- and a-dimensional immunoblotting. 2. The 2D spot patterns become more complex with increasing severity of stress (34 degrees C > 31 degrees C + Cd > 31 degrees C > 20 degrees C). 3. A stress-inducible transgene construct is minimally active at 31 degrees C, but is abundantly expressed in the presence of cadmium or at 34 degrees C. 4. Differing degrees or types of stress may differentially induce available hsp70