Fiona C Broackes-Carter et al. (2005) International Worm Meeting "Systematic analysis of C. elegans gonadogenesis"

Fiona C Broackes-Carter, Andrew M Spence

[International Worm Meeting, 2005]

In newly hatched larvae of C. elegans the gonad primordium consists of 4 cells named Z1-Z4. Z2 and Z3 are primordial germ cells, and Z1 and Z4 divide to produce the somatic gonad through invariant, sex-specific cell lineages.The current release of WormBase lists approximately 1200 genes whose inhibition by RNAi causes sterility. Some, such as tra-1 and gon-1, have established roles in gonad formation. The remainder are otherwise uncharacterized, and their roles in assuring fertility are not understood. To extend and deepen the annotation of these genes I am systematically testing them for roles in somatic gonadogenesis by analyzing the effect of their inhibition by RNAi upon the expression patterns of a panel of reporters of somatic gonad cell fates. I will present a progress report on the screen.

Carter PW et al. (1989) International C. elegans Meeting "molecular analysis of zyg-11."

Roos JM, Carter PW, Kemphues KJ

[International C. elegans Meeting, 1989]

Carter PW et al. (1987) International C. elegans Meeting "progress toward cloning zyg-9 and zyg-11."

Kemphues KJ, Carter PW

[International C. elegans Meeting, 1987]

Katherine Olsson Carter et al. (2003) International Worm Meeting "Temporal regulation of neuronal maturation in C. elegans"

Shin-Yi Lin, Katherine Olsson Carter, Frank Slack

[International Worm Meeting, 2003]

Developmental processes such as neurotransmitter production, synaptic remodeling, and axon outgrowth are temporally regulated in C. elegans, and occur at distinct times in different neuronal subtypes. For instance, serotonin production in the hermaphrodite specific neurons (HSNs) is known to occur at the L4/adult transition, and axon outgrowth is observed at the L3/L4 transition in the VC ventral cord neurons, but one stage later in the HSNs.Genes that regulate the timing of development in C. elegans hypodermal tissues have been identified and ordered into a dedicated pathway of temporal control, the heterochronic pathway. Three of these genes, lin-4, lin-14, and lin-28, are known to affect multiple tissue types, and lin-14 is involved in synaptic remodeling of the DD neurons at the L1 larval stage. The extent to which other genes in the pathway are involved in temporal regulation of neuronal development-and whether they control timing via the same mechanisms-has not been methodically studied.The effects of knocking down or knocking out known heterochronic genes have been investigated for two timed events, the initiation of serotonin synthesis in the HSNs and axon outgrowth in the VCs, using gfp fusion constructs tph-1::gfp and lin-11::gfp, respectively. These studies suggest that timing of developmental events in hypodermal and neural tissues is regulated by at least some of the same genes, including hbl-1, lin-28, and lin-4. However, heterochronic genes lin-29 and let-7 appear to exert opposite effects on timing of HSN serotonin synthesis and hypodermal development. It is thus likely that both within the nervous system, as well as among different tissues, timed events are regulated by a combination of cell-specific and heterochronic genes.

Watts JL et al. (1991) International C. elegans Meeting "ANALYSIS OF ZYG-11 PROTEIN IN EARLY EMBRYOS OF C. ELEGANS"

Kemphues KJ, Watts JL

[International C. elegans Meeting, 1991]

zyg-11 is a maternally acting gene which is required for embryogenesis in C. elegans (Kemphues et al., Dev. Biol. 113, 449-460, 1986). The zyg-l l gene product is necessary for the proper completion of meiosis as well as for certain cytoplasmic and nuclear events of the first cell cycle. The sequence of zyg-11 does not reveal any significant homologies to other EMBL-GenBank sequences (Carter et al., Mol Gen Genet (1990) 221:72-80). Even though zyg-l 1 mutations show a strict maternal effect, zyg-l 1 RNA is not germline specific, as it is expressed in bn2 worms which lack a germ line. We have raised polyclonal antibodies against a trpE- zyg -11 fusion protein. Our antibody recognizes the fusion protein as well as a prominent band of approximately 90kD in N2 worm and embryo preps, corresponding to the predicted size of the zyg-11 protein. Affinity purified antibody stains the nuclear envelope of early embryos in a cell cycle dependent fashion and also stains muscle in larvae and adult worms. We are currently analyzing the localization and abundance of zyg-l l protein in zyg-ll mutants and bn2 worms.

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.

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.

Pilgrim DB et al. (2000) West Coast Worm Meeting "Maternal UNC-45 protein co-localizes with NMY-2, a non-muscle myosin at the cleavage furrow of early embryos"

Pilgrim DB, Ao W

[West Coast Worm Meeting, 2000]

unc-45 is an essential gene for normal body wall muscle thick filament development and mutants show a partial maternal effect. The unc-45 protein product (UNC-45) contains tetratricopeptide (TPR) repeats and similarity to fungal proteins, but its biochemical function is still unknown. We have previously shown that UNC-45 is a component of muscle thick filaments and co-localizes with myosin heavy chain B but not myosin heavy chain A in the body wall muscles of adult worms[1]. Previous genetic evidence also suggests that UNC-45 may interact with myosin heavy chain isoforms in the muscle cells [2]. We show here that UNC-45 is also contributed maternally to the embryos and present in all cells of the early embryo. Zygotic UNC-45 is only detected in the developing muscle cells of the embryo. Moreover, our yeast two-hybrid screens show that UNC-45 interacts specifically with NMY-2, a non-muscle myosin. These two proteins are also co-localized at the cleavage furrow of the early embryos. The localization of UNC-45 at the cleavage furrow is dependent on the presence of NMY-2. NMY-2 has been previously shown to be required for embryonic polarity and cytokinesis [3,4]. Our results suggest that the maternal UNC-45 may have a function in the early embryo which is independent of muscle function. References 1. Ao, W., and Pilgrim, D. (2000). J. Cell Biol. 148, 375-384. 2. Venolia, L., and R.H. Waterston. (1990). Genetics. 126, 345-354. 3. Guo, S., and Kemphues, K. J. (1996). Nature, 382, 455-458. 4. Shelton, C. A., Carter, J. C., Ellis, G. C., and Bowerman, B. (1999). J. Cell Biol. 146, 439-451.

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.