Agbunag C et al. (1997) International C. elegans Meeting "MOLECULAR ANALYSIS OF GENES REQUIRED FOR EMBRYO MORPHOGENESIS"

Priess JR, Agbunag C, Costa M

[International C. elegans Meeting, 1997]

We have conducted molecular analyses of C. elegans genes that control cytoskeletal organization in the hypodermis. Specifically, our work focuses on hmp-1, hmp-2, and hmr-1 mutants that arrest elongation during embryo morphogenesis. We have cloned these genes and found each one to be homologous to components of vertebrate adherens junctions: a-catenin, b-catenin, and cadherin, respectively. The use of the GFP reporter molecule revealed HMP-1 localization to adherens junctions in the hypodermis, intestines, and pharynx, as well as expression in neuronal cell types. Furthermore, these experiments have shown that the 5' 2.0 Kb genomic fragment is sufficient to localize HMP-1 to adherens junctions. This region, which includes the first 240 amino acids, requires HMP-2 for localization to adherens junctions. We have recently obtained transgenic rescue with genomic fragments for the hmp-2 and hmr-1 mutants. We are conducting similar analyses of protein localization and expression patterns on both these genes. Additionally, we are investigating interactions of all these components to determine the mechanisms by which they function in cytoskeletal organization and embryo morphogenesis.

WB Raich et al. (1999) International C. elegans Meeting "The cadherin-catenin complex stabilizes filopodial adhesive contacts during hypodermal morphogenesis"

WB Raich, C Agbunag, J Hardin, JR Priess

[International C. elegans Meeting, 1999]

The sealing of epithelial sheets via the formation of adherent cell-cell junctions is an important morphogenetic event during animal development, yet little is known about how migratory epithelia modulate their junctional connections. The three dimensional shape of embryonic epithelia makes their analysis difficult, and perturbation of junctional molecules via mutation or RNA interference typically disrupts epithelia prior to sheet sealing. Mutations in the C. elegans cadherin hmr-1 , a -catenin hmp-1 , and b -catenin/armadillo hmp-2 are a valuable exception, as these molecules are not essential for general cell adhesion (M. Costa et al., 1998. J. Cell Biol. 141 , 297-308). We have used time-lapse multiphoton laser scanning microscopy to analyze the mechanisms of migration and sealing of the C. elegans hypodermis during ventral enclosure at the subcellular level. Cell-cell junctions were visualized using two reporters: HMP-1-GFP and JAM-1-GFP (for "junction associated molecule"; JAM-1 is recognized by the MH27 monoclonal antibody). HMP-1-GFP is distributed uniformly throughout filopodia extended by the first ventral hypodermal cells to reach the midline ("leading cells"). By 5 min after their contact at the ventral midline, HMP-1 a -catenin rapidly accumulates at future sites of junction formation between contralateral cells. JAM-1 is inserted at ventral midline junctions 15 min following a -catenin accumulation. Cadherin-mediated adhesive strengthening is specifically required to stabilize initial adhesion events between filopodia; in embryos lacking hmr-1 or hmp-1 mRNA, leading cells approach the midline, establish filopodial contact, but do not form stable junctional connections. In addition, in the absence of HMR-1, ectopic and precocious cell-cell fusions occur between hypodermal cells that reach the ventral midline. In contrast, posterior ventral hypodermal cells, which do not display long filopodia, can make correct attachments at the ventral midline in the absence of HMR-1 or HMP-1. Our results indicate that embryonic epithelial cells that use filopodia for migration require recruitment of a -catenin at sites of nascent junction formation to correctly regulate mature junction assembly.

Von Stetina, Stephen E. et al. (2009) International Worm Meeting "Finding Regulators of Cadherin-Independent Epithelialization."

Mango, Susan E., Von Stetina, Stephen E.

[International Worm Meeting, 2009]

How are polarized epithelia established and maintained? This question is of critical importance, as the loss of epithelial polarity is associated with metastasis(1). There are many well-studied protein complexes that lie in specific membrane compartments with roles integral to the epithelial cell. The E-cadherin-containing adherens junction serves to link neighboring epithelial cells together while the more basal tight junction functions to separate the apical and basolateral surfaces. For some cells, E-cadherin is the major initiator of cell polarity and epithelium formation via cell-cell adhesion(2). However, recent studies have discovered E-cadherin independent polarity pathways(3-6). C. elegans offers a powerful system to study this cadherin-independent mechanism, as E-cadherin is dispensible for the initiation of epithelial polarity in nematodes(4). We study cadherin-independent epithelium formation during pharynx development. Nine pharyngeal arcade cells undergo a mesenchymal-to-epithelial transition to link the pharynx to the outer epidermis(7). Ablation of the arcade cells results in a Pharynx unattached (Pun) phenotype, in which the pharynx fails to connect to the epidermis(7). Pun animals die as they are unable to eat. Our lab has undertaken a genetic screen for Pun mutants that fail to form the arcade cell epithelium (Portereiko and Mango, unpublished). This screen revealed that loss of the central-spindlin component ZEN-4/MKLP1 induces a Pun phenotype because the arcade cells fail to polarize(8). We are currently studying where and when ZEN-4 is needed for arcade cell polarization. We have also undertaken a structure/function analysis of this mitotic kinesin in order to elucidate its role in epithelialization. In addition, we are in the process of cloning several mutants that were isolated in the Pun mutagenesis screen. (1). J. M. Lee, S. Dedhar, R. Kalluri, E. W. Thompson, J Cell Biol 172, 973 (Mar 27, 2006). (2). L. N. Nejsum, W. J. Nelson, J Cell Biol 178, 323 (Jul 16, 2007). (3). A. F. Baas et al., Cell 116, 457 (Feb 6, 2004). (4). M. Costa et al., J Cell Biol 141, 297 (Apr 6, 1998). (5). T. J. Harris, M. Peifer, J Cell Biol 167, 135 (Oct 11, 2004). (6). W. B. Raich, C. Agbunag, J. Hardin, Curr Biol 9, 1139 (Oct 21, 1999). (7). M. F. Portereiko, S. E. Mango, Dev Biol 233, 482 (May 15, 2001). (8). M. F. Portereiko, J. Saam, S. E. Mango, Curr Biol 14, 932 (Jun 8, 2004).

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.