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[
Curr Genomics,
2007]
Unbiased genome-wide studies of longevity in S. cerevisiae and C. elegans have led to the identification of more than one hundred genes that determine life span in one or both organisms. Key pathways have been uncovered linking nutrient and growth factor cues to longevity. Quantitative measures of the degree to which aging is evolutionary conserved are now possible. A major challenge for the future is determining which of these genes play a similar role in human aging and using that information to develop therapies toward age-associated diseases.
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[
Mycologia,
1936]
In Zopf's account of tha capture of nematodes by Arthrobotrys oligospora Fres. and Monosporidium repens Zopf were described, apparently for the first time, instances of a biological habit comparable in part to the carnivorous habit of insectivorous flowering plants. More recently nearly a score of additional fungi occurring in soil, in leaf mold, and in solid decaying materials generally, have been found to capture and consume nematodes in large numbers; evidently, indeed, subsisting in nature entirely through such predacious activity. By far most of these fungi are closely related to those dealt with by Zopf, being referable to a group of interrelated genera including Arthrobotrys, Trichothecium, Cephalothecium, Dactylaria, Dactylella and Monacrosporium. The relatively few nematode-capturing forms alien to this hyphomycetous series are conidial phycomycetes belonging to a Zoopagaceae, a family whose known members are mostly destructive to terricolous amoebae, some operating in parasitic, other predacious relationships. Of the few species preying on nematodes, only one, Stylopage hadra Drechsl., has hitherto been described in detail; so that the description offered herein, of a second species of like biological habit, may be of interest even in the absence of pronounced departures in morphology.
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[
PLoS One,
2014]
The rapid pace of species discovery outstrips the rate of species description in many taxa. This problem is especially acute for Caenorhabditis nematodes, where the naming of distinct species would greatly improve their visibility and usage for biological research, given the thousands of scientists studying Caenorhabditis. Species description and naming has been hampered in Caenorhabditis, in part due to the presence of morphologically cryptic species despite complete biological reproductive isolation and often enormous molecular divergence. With the aim of expediting species designations, here we propose and apply a revised framework for species diagnosis and description in this group. Our solution prioritizes reproductive isolation over traditional morphological characters as the key feature in delineating and diagnosing new species, reflecting both practical considerations and conceptual justifications. DNA sequence divergence criteria help prioritize crosses for establishing patterns of reproductive isolation among the many species of Caenorhabditis known to science, such as with the ribosomal internal transcribed spacer-2 (ITS2) DNA barcode. By adopting this approach, we provide new species name designations for 15 distinct biological species, thus increasing the number of named Caenorhabditis species in laboratory culture by nearly 3-fold. We anticipate that the improved accessibility of these species to the research community will expand the opportunities for study and accelerate our understanding of diverse biological phenomena.
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[
J Nematol,
2019]
The genus <i>Pristionchus</i> (Kreis, 1932) consists of more than 30 soil nematode species that are often found in association with scarab beetles. Three major radiations have resulted in the "<i>maupasi</i> species group" in America, the "<i>pacificus</i> species group" in Asia, and the "<i>lheritieri</i> species group," which contains species from Europe and Asia. Phylogenetic analysis indicates that a group of three species, including the gonochorists <i>P. elegans</i> and <i>P. bucculentus</i> and the hermaphrodite <i>P. fissidentatus</i>, is basal to the above-mentioned radiations. Two novel species are described here: <i>Pristionchus paulseni</i> sp. n. from Taiwan and <i>P. yamagatae</i> sp. n. from Japan by means of morphology, morphometrics and genome-wide transcriptome sequence analysis. Previous phylotranscriptomic analysis of the complete <i>Pristionchus</i> genus recognized <i>P. paulseni</i> sp. n. as the sister species of <i>P. fissidentatus</i>, and thus its importance for macro-evolutionary studies. Specifically, the gonochorist <i>P. paulseni</i> sp. n. and the hermaphrodite <i>P. fissidentatus</i> form a species pair that is the sister group to all other described <i>Pristionchus</i> species. <i>P. paulseni</i> sp. n. has two distinct mouth forms, supporting the notion that the mouth dimorphism is ancestral in the genus <i>Pristionchus</i>.
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[
Curr Biol,
2000]
Recent studies have introduced Oscheius sp. CEW1 as a third nematode species accessible to genetic analysis, joining the better known Caenorhabditis elegans and Pristionchus pacificus. A group of vulva-defective mutants in Oscheius has been identified, with defects not seen in C. elegans.
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[
Opuscula Zoologica (Budapest),
1985]
In the present article three new genera and twelve new species of Nematoda are described from Hungary. Seleborca gen. n. (Cephalobidae, Acrobelinae) is similar to Acrobeles but differs from it by the double cuticle and the structure of the lateral field. Hoplorhynchus gen. n. (Hoplolaimidae, Rotylenchinae) is unique among the genera of Hoplolaimidae in the structure of lateral field, in the shape of the tail and in the location of phasmids. Labronemella gen. n. (Qudsianematidae) resembles Lobronema but has a discolaimoid head and a very slender spear. The new species are: Penzancia terricola, Theristus pannonicus, Metateratocephalus gracilicaudatus, Acrobeles canalis, Caenorhabditis cervi, Hoplorhynchus riparius, Ogma danubiale, Ogma castellanum, Trischistoma gracile, Aulolaimus autumnalis, Labronema pusillum and Labronemella labiata spp.n. The genera Penzancia (De Man, 1889) Filipjev, 1918, Acrobeles Linstow, 1877, Trischistoma Cobb, 1913, Tripylina Brzeski, 1963 are redefined and their species listed. To each genus Metateratocephalus Eroshenko, 1973, Acrobeles Linstow, 1877, Seleborca gen.n., Trischistoma Cobb, 1913, Tripylna Brezeski, 1963, Aulolaimus Da Man, 1880 and Labronemella gen. n. a key is
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[
Nematologica,
1964]
A commercially available crude liver medium capable of supporting the axenic cultivation of Caenorhabditis briggsae and Caenorhabditis elegans has been found. It is Bacto-Liver (manufactured by Difco Laboratories Incorporated) - a desiccated and powdered form of fresh liver that has been found to sustain the growth and reproduction of these species. The medium is prepared by Seitz-filtering a 10% suspension of the powdered liver.
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[
Cell,
2023]
In this issue of Cell, we see first evidence of sleep-dependent circuit remodeling alongside behavioral memory consolidation in C.&#
xa0;elegans. Examining memory of a never-rewarded odor during post-training sleep from synapse to behavior all in one organism opens the opportunity to use this well-mapped nervous system to study mechanisms of sleep-dependent memory consolidation.
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[
Genetics,
2006]
Among a large number of homologous gene clusters in C. elegans, two gene families that appear to undergo concerted evolution were studied in detail. Both gene families are nematode-specific and encode small secreted proteins of unknown function. For both families in three Caenorhabditis species, concerted groups of genes are characterized by close genomic proximity and genes in inverted orientation. The rate of protein evolution in one of the two families could be calibrated by comparison with a closely-related non-concerted singleton gene with one-to-one orthologs in all three species. This comparison suggests that protein evolution in concerted gene clusters is two to seven-fold accelerated. A broader survey of clustered gene families, focused on adjacent inverted gene pairs, identified an additional seven families in which concerted evolution probably occurs. All nine identified families encode relatively small proteins, eight of them encode putative secreted proteins, and most of these have very unusual amino acid composition or sequence. I speculate that these genes encode rapidly evolving anti-microbial peptides.
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[
Genetics,
2002]
The free-living nematode worm Caenorhabditis elegans reproduces primarily as a self-fertilizing hermaphrodite, yet. males are maintained in wild-type populations at low frequency. To determine the role of males in C. elegans, we develop a mathematical model for the genetic system of hermaphrodites that can either self-fertilize or be fertilized by males and we perform laboratory observations and experiments on both C. elegans and a related dioecious species C. remanei. We show that the mating efficiency of C. elegans is poor compared to a dioecious species and that C. elegans males are more attracted to C. remanei females than the), arc to their conspecific hermaphrodites. We postulate that a genetic mutation occurred during the evolution of C. elegans hermaphrodites, resulting in the loss of an attracting sex pheromone present in the ancestor of both C. elegans and C. remanei. Our findings suggest that males are maintained in C. elegans because of the particular genetic system inherited from its dioecious ancestor and because of nonadaptive spontaneous nondisjunction of sex chromosomes, which occurs during meiosis in the hermaphrodite. A theoretical argument shows that the low frequency of male mating observed in C. elegans can support male-specific genes against mutational degeneration. This results in the continuing presence of functional males in a 99.9% hermaphroditic species in which outcrossing is disadvantageous to hermaphrodites.