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J Nematol,
1976]
Cultures of C. elegans containing a high proportion of males were subjected to chemotactic tests by using the method of countercurrent separation. The responses of males and hermaphrodites were determined. Both types of worms preferred Na over 1/2 Ca(2), Cl over NO; they were attracted to NaCl, OH, cyclic AMP, pyridine, CO, in borate buffer (pH 8.8); and avoided CO in phosphate buffer (pH 6.0), D-tryptophan, and acid. It was thus concluded that male C. elegans have the same chemotactic responses that hermaphrodites of this species are known to have.
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J Virol,
2017]
Since 1999, Caenorhabditis elegans has been extensively used to study microbe-host interactions due to its simple culture, genetic tractability, and susceptibility to numerous bacterial and fungal pathogens. In contrast, virus studies have been hampered by a lack of convenient virus infection models in nematodes. The recent discovery of a natural viral pathogen of C. elegans and development of diverse artificial infection models are providing new opportunities to explore virus-host interplay in this powerful model organism.
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J Exp Zool,
1975]
In chemotactic studies employing countercurrent separation the nematode Caenorhabditis elegans was found to avoid D-tryptophan with a threshold in the range 10(-4) to 10(-3) M. There was no response to L-tryptophan up to 10(-2) M although it appeared to partially inhibit the response to D-tryptophan.
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[
Genetics,
1975]
The technique of countercurrent separation has been used to isolate 17 independent chemotaxis-defective mutants of the nematode Caenorhabditis elegans. The mutants, selected to be relatively insensitive to the normally attractive salt NaCl, show varying degrees of residual sensitivity; some are actually weakly repelled by NaCl. The mutants are due to single gene defects, are autosomal and recessive, and identify at least five complementation groups.
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Genome Res,
1998]
With the completion of the Genome Sequencing Project, it is now possible to rapidly and accurately determine the frequency and position of a particular repeat sequence in the Caenorhabditis elegans genome. Several repeat sequences with a variety of characteristics have been examined and with few exceptions they show a near-random distribution throughout the genome. We characterized several genes near the left end of Chromosome III in the C. elegans genome, and found a 24-bp minisatellite repeat sequence present in the introns of two unrelated genes. This prompted a search of the databank for other occurrences of this sequence. Multiple copy arrays of this repeat are all located on the same autosome and fall in two clusters: one near the left end, and one in the central region separated by approximately 10 Mb. There are >200 copies of this repeat on the chromosome. This euchromatic repeat sequence seems unrelated to gene expression, is absent from homologous sites in a related species, is unstable in Escherichia coli, and is polymorphic between different wild isolates of C. elegans. Most CeRep25B units in the array match the consensus sequence very well, suggesting that either this repeat originated quite recently or its sequence is functionally constrained. Although chromosome-specific repeat sequences have been reported previously in many organisms, such sequences are usually structural and heterochromatic (e.g., centromeric alpha-satellite) or on the mammalian sex chromosomes. This report describes the first confirmed instance from a whole genome sequencing project of an autosomal euchromatic chromosome-specific minisatellite repeat.
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[
Comp Biochem Physiol C,
1976]
1. The nematode C. elegans is attracted to pyridine. 2. The threshold is about 0.1 mM. 3. At concentrations above 1 mM the response weakens. 4. No indication of avoidance of high concentrations could be found.
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Journal of Comparative Physiology,
1980]
Using a technique of recording the behavior of individual nematodes during exposure to various solutions, it was demonstrated that C. elegans made more reversal behaviors after transfer to solutions of lower oxygen tension than higher. The response was stronger after the first hour in the apparatus than initially. This change was not dependent on reduced oxygen availability during the initial period. Starvation is the most likely cause of this change. A variety of mutant strains of C. elegans that are defective in response to most known chemotactic stimuli, including two strains that have been shown to be severely abnormal in the ciliated endings of all sensory neurons of the worm's snout, all responded to changes in oxygen tension. This observation suggests that oxygen is sensed internally rather than by specialized receptor cells.
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Journal of Comparative Physiology,
1980]
A new method is described for studying the behavioral responses of nematodes to controlled chemical stimulation. The worm is held by the tail with a suction pipet. Behavior is recorded by an array of light sensors connected to a multichannel recorder. Several types of behavior can be detected in addition to the normal backward propagating waves of about 2 Hz that propel untethered worms forward. The most dramatic of these is the reversal bout, consisting of forward propagating waves of about 0.7 Hz, that propel untethered worms backward. The latter waves are easily distinguished from the former by the large amplitude motion caused by the fact that they contain a sharper bend at the tail. This technique was used to demonstrate that a purely temporal change in chemical stimulation can cause a large change in the probability of occurrence of a reversal bout. These altered probabilities adapt back to the basal level in about one minute. Increased probabilities adapt faster than decreased. Stronger stimulation causes slower adaptation. Since the reversal bout is associated with changes in direction of locomotion, these observations suggest that klinokinesis with adaptation plays a role in the movement of nematodes in chemical gradients.
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J Exp Zool,
1974]
C. elegans responds to several common chemicals. Comparisons of pairs of ions at equivalent concentrations indicated orders of attractiveness of: Na+ > K+ > 1/2 Mg++ > 1/2 Ca++. Cl- > 1/2 SO4-- > NO3- > CH3COO-. The least attractive pair of ions, calcium acetate, is attractive, indicating all these ions are attractive. The most attractive pair, sodium chloride, was attractive from a threshold of 0.1 mM to at least 50 mM. The response to NaCl was maximal throughout the temperature range 15 to 25C and the pH range 3.0 to 9.0. Acid was avoided and base was attractive from concentrations of 0.1 to 1 mM. Dissolved CO2 in the concentration range 0.1 to 1 mM was attractive in 10 mM sodium borate buffer, pH 8.8, but avoided in 25 mM potassium phosphate, pH 6.0. All these responses are likely to affect the distribution of C. elegans in nature and they also provide a tool for promising studies in
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Genome,
1993]
A genetic approach was taken to identify new transposable element Tc1-dependent polymorphisms on the left end of linkage group III in the nematode Caenorhabditis elegans. The cloning of the genomic DNA surrounding the Tc1 allowed the selection of overlapping clones (from the collection being used to assemble the physical map of the C . elegans genome). A contig of approximately 600-800 kbp in the re-ion has been identified, the genetic map of the region has been refined, and 10 new RFLPs as well as at least four previously characterized genetic loci have been positioned onto the physical map. to the resolution of a few cosmids. This analysis demonstrated the ability to combine physical and genetic mapping for the rapid analysis of large genomic regions (0.5-1 Mbp) in genetically amenable eukaryotes.