Hansen, M. et al. (2019) International Worm Meeting "Determining the role of ztf-16 in regulating cell fate in stem cell-like cells after quiescence."

Kohtz, C., Brown, C., Kim, J., Vargus, M., Alessi, A., Hansen, M., Rougvie, A., Karp, X., Bernstein, T., Daul, A., Montoye, E.

[International Worm Meeting, 2019]

Multipotent adult stem cells typically exist in a state of reversible cell cycle arrest known as quiescence; however, the mechanisms maintaining multipotency during quiescence are relatively unknown. C. elegans contains stem cell-like seam cells that undergo stage-specific division patterns and eventual terminal differentiation. C. elegans larvae develop either continuously or through dauer-interrupted life history. Dauer occurs after the second larval molt in response to stress, and during dauer, seam cells remain multipotent and quiescent. If conditions improve, dauer larvae recover and their seam cells complete development normally. Heterochronic genes ensure correct temporal control of seam cell fate. Many heterochronic genes required during continuous development are dispensable after dauer, suggesting a separate developmental pathway. Through a genetic screen, we identified ztf-16, which encodes a transcription factor related to HBL-1. We find ztf-16 necessary to prevent precocious expression of the adult-specific marker col-19::gfp during both life histories. Based on the relationship between hbl-1 and ztf-16, we explored potential interactions between these genes in regulating L2 cell fate. During continuous development, but not post-dauer, the loss of ztf-16 enhances the cell fate defects of hbl-1 mutants. To further investigate L2 cell fates, we are now exploring the relationship between ztf-16 and the microRNAs that downregulate hbl-1 to allow progression to L3 cell fate. To determine the role of ztf-16 in adult cell fate, we examined genetic interactions between ztf-16 and lin-29. Unexpectedly, our data suggest that ztf-16 acts at least partially in parallel to lin-29 and uncouples the regulation of col-19::gfp from that of adult alae. We have also tagged the endogenous ztf-16 gene with both EGFP and mScarlet to characterize the expression of ZTF-16 throughout both life histories. By characterizing ztf-16, we hope to shed light on the mechanisms that control stem cell fate during and after quiescence.

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.

Schartner, Caitlin M. et al. (2015) International Worm Meeting "X-chromosome evolution: divergence of X-sequence motifs that drive dosage compensation across Caenorhabditis species."

Meyer, Barbara J., Lo, Te-Wen, Schartner, Caitlin M.

[International Worm Meeting, 2015]

Dosage compensation (DC) across Caenorhabditis species exemplifies an essential process that has undergone rapid co-evolution of protein-DNA interactions central to its mechanism. In C. elegans, recruitment elements on X (rex sites) recruit a condensin-like DC complex (DCC) to hermaphrodite X chromosomes to balance gene expression between the sexes. Recruitment assays in vivo showed that C. elegans rex sites do not recruit the DCC of C. briggsae, and vice versa. To understand how DC complexes and X chromosomes evolved to use different X targeting sequences, we compared DCC subunits and binding sites in C. elegans to those in three species of the C. briggsae clade (15-30 MYR diverged): C. briggsae, its close relative C. nigoni (C. sp. 9), and C. tropicalis (C. sp. 11). By raising antibodies and introducing endogenous tags with TALENs or CRISPR/Cas9, we showed that homologs of both SDC-2, the pivotal X targeting factor, and DPY-27, a DCC-specific condensin subunit, bind X chromosomes of XX animals. Although the DCC shares key components across these four species, the binding sites differ. First, ChIP-seq studies in C. briggsae and C. nigoni identified DCC binding sites that are homologous across these close relatives but differ from C. elegans sites in sequence and location. Second, C. elegans sites use motifs enriched on X (MEX and MEXII) to drive DCC binding, but these motifs are not in C. briggsae or C. nigoni DCC sites and are not X-enriched. Third, we found an X-enriched motif at DCC binding sites of C. briggsae and C. nigoni that is not X-enriched in C. elegans. An oligo with the C. briggsae motif recruits the DCC in C. briggsae, but a similar oligo lacking the motif fails to recruit, establishing the importance of the motif. Fourth, another motif was found in C. briggsae and C. nigoni that shares a few nucleotides with MEX, but its functional divergence was shown by C. elegans recruitment assays. Fifth, two endogenous C. briggsae X-chromosome regions with strong C. elegans MEX motifs fail to recruit the C. briggsae DCC, as assayed by ChIP-seq and recruitment assays. None of these DCC motifs is enriched on the C. tropicalis draft X sequence, supporting further binding site divergence within the C. briggsae clade. Ongoing ChIP-seq studies in C. tropicalis will help determine how C. elegans and C. briggsae clade motifs are evolutionarily related. Comparison of DCC targeting mechanisms across these four species allows us to characterize a rarely captured event: the recent co-evolution of a protein complex and its rapidly diverged target sequences across an entire X chromosome.