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[
Nature,
1996]
Springtime finds hopeful anglers baiting hungry fish with twitching worms, both live and artificial. Fish prefer the large annelids, but Kemp and coworkers have knotted on their lines the small, alluring nematode Caenorhabditis elegans, which twitches spasmodically when the aptly named protein twitchin goes missing from its muscle cells. And they've caught a big one! On page 636 of this issue, these authors report that the giant protein kinase twitchin, which has a relative molecular mass of 750K and is found in nematode muscle cells, and the protein S100A1(2), a member of the S100 family of calcium-binding proteins, make up a third new calcium-regulated system in muscle which may be of great importance in organizing muscle structure and maintaining its resting tension. They show that a fragment of twitchin containing the autoinhibited kinase domain is specifically activated in a calcium-dependent and zinc-enhanced manner by S100A1(2), but not by the S100B(2) isoform with which it shares 60 percent homology....
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[
Dev Biol,
1979]
Two-dimensional gel electrophoresis has been used to analyze proteins synthesized during postembryonic development of the nematode Caenorhabditis elegans. This organism is favorable for these studies because it has a limited number of cells, it is genetically well-defined, and its development is currently under investigation in several laboratories. 35S-labeled E. coli was used for continuous and pulse labeling of C. elegans during its four juvenile larval stages and as a gravid adult. After continuous labeling or pulse labeling for 1 hr, 600-800 individual spots can be resolved on a 2D gel using fluorography and 2 weeks of exposure. Proteins that represent 0.0017% of the total sample can be detected. Exposure for 12 weeks reveals only 100 additional spots even though the films are not saturated. It therefore appears that the frequency distribution of proteins decreases significantly beyond these 800 most abundant proteins that can be frationated on an O'Farrell gel. When the patterns of pulse-labeled proteins of the five developmental stages were compared, 113 proteins could be seen to undergo modulation at one or more of the developmental stages. A maximum number of changes was seen in the transition from the L4 to the adult stages when 11% of the total spots either appeared, disappeared, or changed in intensity. As controls, different preparations of the same developmental stage were compared and revealed considerable fluctuation, 2.6-4.8%. These fluctuations are presumed to be due to variations in growth conditions during culture of the organism. Continuous label experiments reveal a distinct set of proteins that undergo turnover and/or modification during development. Some of these proteins are absent in only one stage, indicating that stable proteins are also modulated. But nearly all of the proteins seen in a continuous label are also seen in a pulse label indicating that most of the major proteins are
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[
MicroPubl Biol,
2021]
For Johnson, CK; Miller, DD; Bianchi, L (2021). Effect of the protease plasmin on C. elegans hyperactive DEG/ENaC channels MEC-4(d) and UNC-8(d). microPublication Biology. 10.17912/micropub.biology.000412.
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[
Worm Breeder's Gazette,
1976]
Zyg mutants fail to hatch at restrictive temperature. The end of their temperature sensitive periods can be defined relative to hatching. Late L4's and gravid adults are allowed to lay eggs overnight at permissive temperature. By the next day a heterogeneous population of eggs at all stages of embryogenesis is obtained. Only newly hatched L's are removed from the plate which is then shifted to 25 C. In subsequent 1-2 hour intervals newly hatched L's are removed and counted. Hatching rates of 50 to 200 L's per hour are obtained for plates containing 40-50 gravid adults. This rate is dependent, however, on individual mutant egg production. The removal of L's continues until no further hatching is observed. The end of the tcrit is defined to be when the hatching rate is reduced 50%. This method allows us to measure any tcrits that end during gonadogenesis and before egg laying since no adults need be removed. The tcrits in hours before hatching are tabulated below. The maternal versus the non-maternal mode of inheritance for the listed zyg mutants was determined earlier (Boulder Worm Group, 1976). Most of the true maternals (M,M) exhibited tcrits at 11-17 hours before hatching, while the non-maternals (N,N) exhibited tcrits at later times in embryogenesis. Even for mutants that were rescued by wild type sperm (M,N), if the rescue was by a cytoplasmic factor, the tcrit was earlier in embryogenesis compared to the rescue by a zygotic function of normal sperm. To determine more exactly the embryonic stage at the end of the tcrit, individual zygotes were released from gravid adults by dissection and then transferred to plates at 25 C (Hirsh and Vanderslice, 1976). Using a stereomicroscope at 50X magnification, one to sixteen cell stages can be readily distinguished prior to their transfer to restrictive temperatures. For some of the mutants (tsB1 and tsB10) all their 1-16 cell stage embryos hatched. This means that these embryos were past their tcrits, or, their tcrits were before the one cell stage. If the gravid tsB10 mutant for example was initially raised to 25 C for one hour before dissection, 50% of the two cell embryos died. The tcrits for tsB1 and tsB10 were just before and after fertilization respectively, since it takes about two hours for the fertilized egg in C. elegans to reach the two cell stage (Hirsh et al., 1976). Other mutants exhibited temperature sensitive periods during the one to sixteen cell stages. For example, tsB211 failed to hatch if the 1- 4 cell stage embryos were raised to the restrictive temperature while six cell stage embryos or later ones did hatch. Lastly, many of the mutant embryos failed to hatch if any of their 1-16 cell stage embryos were raised to the restrictive temperature, i.e., the end of their tcrit was at a later stage but 6- 9 hours before hatching. As noted above, all the true maternals exhibited early tcrits that were around the time of fertilization and before the 16 blastomere stage. The non-maternals or those that were dependent on zygotic expression for normal embryogenesis exhibited tcrits beyond the 16 cell stage. In conclusion, when a mutation alters a zygotic function necessary for normal embryogenesis, its function is required later in embryogenesis compared to those mutants that require a cytoplasmic factor. [See Figure 1]
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[
J Gerontol A Biol Sci Med Sci,
2005]
The 2002 Kleemeier Award from the Gerontological Society of America was awarded to Thomas E. Johnson, PhD, of the University of Colorado at Boulder. Dr. Johnson was the pioneer who first applied genetic analyses to the study of the aging processes in Caenorhabditis elegans and who introduced the nematode as an aging model. Longer life span was chosen as a surrogate marker for slowed aging. Here Dr. Johnson describes his role(s) in the isolation of
age-1, the first longevity mutant, which can more than double the life span and which slows the rate of aging more than twofold. He also reviews research suggesting conservation of function and applicability to intervention by pharmacological targeting of the Age-1 pathway. Current work by biotechnology companies targets this and other basic discoveries in an attempt to postpone human aging.
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[
BMC Evol Biol,
2011]
BACKGROUND: Genome wide analysis of variation within a species can reveal the evolution of fundamental biological processes such as mutation, recombination, and natural selection. We compare genome wide sequence differences between two independent isolates of the nematode Caenorhabditis elegans (CB4856 and CB4858) and the reference genome (N2). RESULTS: The base substitution pattern when comparing N2 against CB4858 reveals a transition over transversion bias (1.32:1) that is not present in CB4856. In CB4856, there is a significant bias in the direction of base substitution. The frequency of A or T bases in N2 that are G or C bases in CB4856 outnumber the opposite frequencies for transitions as well as transversions. These differences were not observed in the N2/CB4858 comparison. Similarly, we observed a strong bias for deletions over insertions in CB4856 (1.44: 1) that is not present in CB4858. In both CB4856 and CB4858, there is a significant correlation between SNP rate and recombination rate on the autosomes but not on the X chromosome. Furthermore, we identified numerous significant hotspots of variation in the CB4856-N2 comparison.In both CB4856 and CB4858, based on a measure of the strength of selection (ka/ks), all the chromosomes are under negative selection and in CB4856, there is no difference in the strength of natural selection in either the autosomes versus X or between any of the chromosomes. By contrast, in CB4858, ka/ks values are smaller in the autosomes than in the X chromosome. In addition, in CB4858, ka/ks values differ between chromosomes. CONCLUSIONS: The clear bias of deletions over insertions in CB4856 suggests that either the CB4856 genome is becoming smaller or the N2 genome is getting larger. We hypothesize the hotspots found represent alleles that are shared between CB4856 and CB4858 but not N2. Because the ka/ks ratio in the X chromosome is higher than the autosomes on average in CB4858, purifying selection is reduced on the X chromosome.
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[
International C. elegans Meeting,
1979]
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[
West Coast Worm Meeting,
1996]
Life extension is conferred either by mutants extending adult life (Age), including
age-1,
daf-2,
daf-23,
daf-28,
spe-26, and an allele of
clk-1. Another mode of life extension is conferred by mutants delaying developmental stage (Clk), including
clk-1,
clk-2,
clk-3,
gro-1(Wong et al., 1995; Lakowski and Hekimi, 1996). Three groups have identified a life-extension pathway formed by some Daf mutations (Dorman et al., 1995; Larsen et al., 1995; Murakami and Johnson, 1996). We found that the pathway is not limited to Daf mutations but includes other types of the Age mutants (Murakami and Johnson, 1996). Interestingly, the pathway confers UV resistance, suggesting that UV resistance is a good indicator of Age. It is also consistent with the hypothesis that stress resistance is a rate limiting factor determining longevity. We are also testing whether the Age-pathway can confer other types of stress such as H2O2 and heat.
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[
The Journal of NIH Research,
1991]
Cowabugna, dudes! Those lean, gene-revealing machines have scored a most totally excellent victory in the battle to understand aging. We are, of course, talking about mutant ninja nematodes here. At a conference on aging in January at Cold Spring Harbor's Banbury Center, Thomas Johnson of the Institute for Behavioral Genetics at the University of Colorado in Boulder brought some dudes and dudettes from Capitol Hill up to date on the latest awesome achievements of the bodacious beasts know as Caenorhabditis elegans.
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[
Worm Breeder's Gazette,
1986]
Our aim is to obtain peptides of known sequence from Ascaris in order to determine their mode of action using electrophysiological methods. Since McIntire and Horvitz (C. elegans CSH Abstracts 1985) showed that cholecystokinin-like immunoreactivity (CCK-LI) is present in certain neurons in C. elegans, we are initially investigating the role of a CCK-like peptide (CCK-LP) in the nervous system of Ascaris using anti-CCK8 antisera to detect and localize CCK-LI. Using the methods developed by Johnson (see Johnson and Stretton, Soc. Neurosci. Abstr. 9: 302; Sithigorngul, Johnson and Stretton, C. elegans CSH Abstracts 1985) we find that in Ascaris, CCK-LI is concentrated in 2 cells (AVF cells) in the ventral nerve cord, in 3 cells in the ventral ganglion, in 4 processes in the ventral cord, and in 2 processes in the lateral line. Thus the CCK-LP is concentrated in a small minority of the 180 neurons present in the anterior region of adult Ascaris.We have developed a procedure for extracting the CCK- LP from C. elegans and fractionating the extract on a C18 cartridge. High voltage paper electrophoresis shows that added radioiodinated CCK8 is chemically intact after this extraction and after fractionation. The CCK-LP was separated from more hydrophilic components with a 20-40% gradient of acetonitrile on reversed phase HPLC. RIA's detected CCK-LI associated with a peak of optical density. Addition of authentic CCK8 (non-sulfated) to the sample showed that the RIA-positive peak was close to, but distinctly separate from, CCK8. Assuming that the specific immunoreactivity of nematode CCK-LP and mammalian CCK8 is the same, we can obtain 100 pmoles from 60g of C. elegans. From this crude estimate, it seems that the levels of recoverable peptide are sufficient for amino acid sequence determination which is now our top priority.