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[
Worm Breeder's Gazette,
1993]
Cloning of the
lin-32 gene Connie Zhao and Scott W. Emmons, Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461
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[
East Asia C. elegans Meeting,
2006]
Flavonoids produced in plants have anti-oxidative activity showing various effects on animal cells. Due to its simplicity, convenience and a complete genome sequence, C. elegans is an ideal animal model organism to investigate effects of flavonoids. Assay for resistance to oxidative stress was performed to measure anti-oxidative activity of flavonoids after inducing oxidative stress in worms by paraquat (1,1<SUP>,</SUP>-dimethyl-4-4<SUP>,</SUP>-bipyridinium dichloride hydrate). Synchronized worms were grown at 20°C until they reached at a gravid adult stage on plates containing each of quercetin, rutin hydrate, naringenin, naringin, hesperitin and hesperidin. Worms treated with flavonoids were transferred to 80 mM paraquat solution and incubated for 20 h at 20°C. Worms were then transferred onto a fresh agar plate, recovered for 1 h and scored for survival. Survival rates were measured by counting live worms. Hesperidin showed the relatively strong anti-oxidative activity when internal reactive oxygen species were generated by paraquat in C. elegans. This study was supported by KRF2004-F00019 (KRF) and the second BK21 (MOE)
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[
Worm Breeder's Gazette,
1994]
Strain names for non-C. elegans species Scott W. Emmonst, Armand Leroit, and David Fitch, Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, Department of Biology, New York University, RmlOO9 Main Bldg., Washington Square, New York, NY 10003
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[
Nematologica,
1977]
SEM observations of adult Caenorhabditis briggsae females showed differences between young and old nematodes. In young nematodes the cuticle was generally smooth, whereas in old ones it was wrinkled. Deirids were located at the level of the excretory pore in the lateral field. They were distinct in young nematodes but indistinct in old ones. The oral opening was formed by six lips, which were closed in old nematodes and open in young ones. The vulva possessed two semi-circular lips and was bordered by two lateral flaps. These lips were smooth in young specimens and wrinkled in old ones. Cryofractures of old nematodes showed cavities in the intestinal epithelium corresponding to areas in which age pigment granules normally occur. No such cavities were seen in young nematodes.
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[
Elife,
2019]
Young <i>Caenorhabditis elegans</i> hermaphrodites use their own sperm to protect against the negative consequences of mating.
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[
Journal of Nematology,
1972]
The specific gravity of old Caenorhabditis briggsae was shown to be greater than that of young nematodes. The possible explanations for this age-associated change are discussed.
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[
Sci Rep,
2020]
Maternal behaviors benefit the survival of young, contributing directly to the mother's reproductive fitness. An extreme form of this is seen in matriphagy, when a mother performs the ultimate sacrifice and offers her body as a meal for her young. Whether matriphagy offers only a single energy-rich meal or another possible benefit to the young is unknown. Here, we characterized the toxicity of a bacterial secondary metabolite, namely, violacein, in Caenorhabditis elegans and found it is not only toxic towards adults, but also arrests growth and development of C. elegans larvae. To counteract this, C. elegans resorted to matriphagy, with the mothers holding their eggs within their bodies and hatching the young larvae internally, which eventually led to the mothers' death. This violacein-induced matriphagy alleviated some of the toxic effects of violacein, allowing a portion of the internally-hatched young to bypass developmental arrest. Using genetic and pharmacological experiments, we found the consumption of oleate, a monounsaturated fatty acid produced by the mother, during matriphagy is partially responsible. As such, our study provides experimental evidence of why such a drastic and peculiar maternal behavior may have arisen in nematode natural habitats.
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[
Can J Zool,
1982]
Dauerlarvae are reportedly adapted to withstand adverse environmental conditions. Current knowledge of the mechanisms underlying the unique characteristics of dauerlarvae is limited. This study characterizes superoxide dismutase (SODase) activity in several developmental stages of Caenorhabditis elegans (originally described by E. Maupas in 1900). Extracts of dauerlarvae have 17.1 units SODase per milligram protein, as compared with 4.3 and 3.8 units per milligram for obligate larvae and young adults, respectively. Since oxygen consumption in dauerlarvae is lower than that of young adults, the ratio of SODase to oxygen consumption is markedly higher in dauerlarvae than in young adults. The elevated SODase might contribute to an increased resistance to a variety of environmental stresses, including radiation. Furthermore, the elevation of this activity relative to metabolic rate could account for the long life-span of dauerlarvae.
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[
International Worm Meeting,
2011]
We assessed the interplay between body mechanics and touch sensitivity by modulating muscle tone with Channelrhodopsin-2 and measuring force thresholds with a novel force-clamp metrology. Touch sensation is poorly understood despite the prevalence of disrupted touch and associated pain in pervasive diseases like diabetes. C. elegans is an ideal model for touch with its six touch receptor neurons (TRNs) and behavioral response to gentle touch. Force applied to the body results in stress/strain of nearby TRNs, triggering opening of force-gated ion channels, cellular depolarization, and an avoidance response for sufficiently large forces. Previously, we developed a behavioral force-clamp metrology capable of applying nN-mN forces to moving L4/young adult animals (Park et al, Rev Sci Instr, in press). Using this metrology, we showed that wild-type (N2) animals respond to forces ³ 100 nN, revealing unprecedented mechanical sensitivity.
Previously, we showed that the three-layered outer shell (cuticle, hypodermis, and body wall muscle) plays a crucial role in filtering and transmitting applied forces (Park et al, PNAS 104:17376, 2007) and that body wall muscle tone regulates body mechanics (Petzold et al, Biophys J, in press). Now, we are testing the hypothesis that changes in body mechanics modulate touch sensitivity. To do this, we compare force-response curves in un-stimulated and hyper-contracted animals. Preliminary results show that larger forces are needed to evoke avoidance responses in hyper-contracted animals. We used light to manipulate body wall muscle contraction in transgenic animals expressing ChR2 under the control of a body wall muscle-specific promoter. This study provides a way to study the interplay between body mechanics and touch sensitivity in C. elegans and will further our understanding of the role of the outer shell in filtering and transmitting loads to the TRNs.
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[
Cell Genom,
2023]
Gene duplication produces the material that fuels evolutionary innovation. The "out-of-testis" hypothesis suggests that sperm competition creates selective pressure encouraging the emergence of new genes in male germline, but the somatic expression and function of the newly evolved genes are not well understood. We systematically mapped the expression of young duplicate genes throughout development in Caenorhabditis elegans using both whole-organism and single-cell transcriptomic data. Based on the expression dynamics across developmental stages, young duplicate genes fall into three clusters that are preferentially expressed in early embryos, mid-stage embryos, and late-stage larvae. Early embryonic genes are involved in protein degradation and develop essentiality comparable to the genomic average. In mid-to-late embryos and L4-stage larvae, young genes are enriched in intestine, epidermal cells, coelomocytes, and amphid chemosensory neurons. Their molecular functions and inducible expression indicate potential roles in innate immune response and chemosensory perceptions, which may contribute to adaptation outside of the sperm.