Kirsten A Hagstrom et al. (2001) International C. elegans Meeting "Mitotic Chromosome Condensation and Segregation by a Conserved Protein Complex"

Raymond Chan, Barbara J Meyer, Kirsten A Hagstrom

[International C. elegans Meeting, 2001]

The ordered compaction of chromosomes into two condensed and paired sister chromatids is a structural problem of all mitotic cells. If chromosomes fail to establish cohesion or to condense, they can become entangled, and break or missegregate at anaphase. The highly conserved SMC (structural maintenance of chromosomes) protein family directs these critical aspects of chromosome segregation. SMC proteins generally associate with an SMC partner and non-SMC proteins to form large complexes. An SMC complex called condensin was described in other organisms for its role in condensing mitotic chromosomes. In C. elegans , a homologous complex directs X dosage compensation. We are studying the composition and function of SMC complexes, and have found individual SMC proteins that participate in more than one chromosomal process. For example, MIX-1 is a condensin SMC homolog essential for both mitosis and dosage compensation. How does MIX-1 achieve its dual function within a single cell? MIX-1 requires the SMC protein DPY-27 for its role in dosage compensation and its X localization, but DPY-27 plays no role in mitosis. Thus, it seemed likely that MIX-1 would have a different SMC partner for mitosis. Searching the genome revealed another DPY-27-like SMC protein, CeSMC-4. The RNAi phenotype and protein localization of CeSMC-4 indicate its involvement in mitosis. Like MIX-1, CeSMC-4 RNAi produces dead embryos with defects such as anaphase chromatin bridges and extremely large nuclei. In support of the idea that CeSMC-4 and MIX-1 are SMC partners for mitosis, MIX-1 protein is undetectable in CeSMC-4 RNAi embryos. Using histone::GFP and time-lapse microscopy, we see that chromosomes are poorly organized as they condense at prophase and metaphase, remain entangled at anaphase, and eventually become pulled into one cell which continues more cycles of apparent replication without division. Meiotic chromosome segregation defects are also observed. In contrast to the expectation from studies in Xenopus, loss of C. elegans condensin causes chromosomes to be poorly organized but still substantially compacted, and the more dramatic phenotype is instead the chromatin bridges at anaphase. CeSMC-4 and MIX-1 associate with chromosomes only during stages of the cell cycle when chromosomes are condensed. The mitotic kinase AIR-2, responsible for the mitosis-specific phosphorylation of histone H3, is required for CeSMC-4 and MIX-1 localization. CeSMC-4 and MIX-1 proteins do not coat the entire metaphase plate, but rather appear on the poleward face in a punctate pattern coincident with the centromere protein HCP-3, and internal to the kinetochore protein HIM-10. However, localization of these proteins is not interdependent. Immunoprecipitation (IP) experiments substantiate that MIX-1 partners with CeSMC-4 for mitosis, but DPY-27 for dosage compensation. Co-IP from embryonic extracts is observed between CeSMC-4 and MIX-1, but not between CeSMC-4 and DPY-27. Moreover, IPs show that CeSMC-4 and MIX-1 are part of a large protein complex whose additional components are being investigated by mass spectrometry. One subunit called CeCAP-D2 (see R. Chan et al.) shares homology with both a conserved non-SMC component of the mitotic complex in other organisms, and a component of the C. elegans dosage compensation complex. In collaboration with the Cozzarelli lab, the mitotic complex was shown to drive ATP-dependent positive DNA supercoiling in vitro, a conserved activity thought to reflect its role in chromosome condensation. It will be interesting to learn if the mitotic and dosage compensation complexes share additional components, and to what extent the biochemical activities of these two condensin-like complexes are related.

Diesfeld HJ et al. (1981) Tropenmed Parasitol "[Comparative immunofluorescent-histological investigations on 7 nematode species in respect to its antigenic properties for differential diagnosis of nematode infections (author's transl)]."

Diesfeld HJ, Kirsten C, Stappert U

[Tropenmed Parasitol, 1981]

Five nematode species of the Onchocercidae family and one from the Strongylidae and Trichuridae family were tested as antigen in the immunofluorescence test (IIFT) against reference sera from six nematode infections. The localisation of the cytosomal antigen antibody-reaction in the IIFT which was described on D. Viteae, was found to be the same for B. malayi, B. pahangi, L. carinii, O. volvulus and A. caninum. This test, just as egg membrane crude preparations of 5 nematodes from the Onchocercidae family, could not differentiate between W. bancrofti, onchocerciasis, loiasis and D. perstans sera. The cuticular fluorescence of five Onchocercidae species, which was observed only in frozen sections, appeared only with W. bancrofti-filariasis and onchocerciasis sera. T. spiralis larvae antigen exhibited only cuticular fluorescence in the frozen section, but in the case, however, against all reference sera. Trichinellosis patients' serum reacted on the other hand only with T. spiralis antigen. Uterine microfilaria from B. malayi, L. carinii, O. volvulus and D. viteae could differenciate species specifically between reference sera.

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

Xu J et al. (2018) J Nanosci Nanotechnol "Carbon Quantum Dots as Fluorescent Probes for Imaging and Detecting Free Radicals in C. elegans."

Wang Q, Guan S, Wang L, Wang M, Zhang Y, Mu Y, Xu J, Wang K, Li J

[J Nanosci Nanotechnol, 2018]

Uniform and hydrophilic carbon quantum dots (C-QDs) were synthesized by calcination and NaOH treatment from an organo-templated zeolite precursor. The color of luminescence was determined by the concentration of C-QDs. These variable-color C-QDs were applied for the first time in the imaging of Caenorhabditis elegans (C. elegans) as a model organism. The effects of C-QDs and possible behavioral changes in C. elegans were evaluated under treatment conditions. We could clearly observe distribution of C-QDs in C. elegans from the fluorescence images. Furthermore, we observed significant and detectable fluorescence quenching of the C-QDs by free radicals in C. elegans. Our work affirms that C-QDs can be developed as imaging probes and as potential fluorescent quantitative probes for detecting free radicals.

Karin Kiontke et al. (2008) Development & Evolution Meeting "New Phylogeny Of Caenorhabditis Including Recently Discovered Species"

David Fitch, Karin Kiontke, Marie-Anne FELIX

[Development & Evolution Meeting, 2008]

Recently, seven new Caenorhabditis have been discovered, bringing the number of Caenorhabditis species in culture to 17, 10 of which are undescribed. To elucidate the relationships of the new species to the five species with sequenced genomes, we have used sequence data from two rRNA genes and several protein-coding genes for reconstructing the phylogenetic tree of Caenorhabditis. Four new species (spp. 5, 9, 10, 11) group within the so-called Elegans group of Caenorhabditis, with C. elegans being the first branch. Whereas none of them is likely to be the sister species of C. elegans, we now know of two close relatives of C. briggsae-C. sp. 5 and C. sp. 9. C. sp. 9 can hybridize with C. briggsae in the laboratory [see abstract by Woodruff et al.]. Of the remaining new species, C. sp. 7 branches off between C. elegans and C. japonica. This species is easier to cultivate than C. japonica and may be a better candidate for comparative experimental work. Two of the new species branch off before C. japonica as sister species of C. sp. 3 and C. drosophilae+C. sp. 2, respectively. Only one of the new species, C. sp. 11, is hermaphroditic. The position of C. sp. 11 in the phylogeny suggests that hermaphroditism evolved three times within the Elegans group. Two of the new species were isolated from rotting leaves and flowers, and five from rotting fruit. Rotting fruit is also the habitat in which C. elegans has been found to proliferate (Barriere and Felix, Genetics 2007) and from which C. briggsae, C. brenneri and C. remanei were repeatedly isolated. This suggests that the habitat of the stem species of Caenorhabditis after the divergence of the earliest branches (C. plicata, C. sonorae and C. sp. 1) was rotting fruit. The rate of discovery of new Caenorhabditis species has steadily increased since the description of C. elegans in 1899, with a leap in the last two years. There is no indication that we are even close to knowing all species in this genus.