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[
International Worm Meeting,
2019]
Human metabolic diseases are becoming increasingly common and understanding the role genetic mutation plays in these diseases is an important first step in treatment. Large GWAS studies conducted on the human metabolome have shown that only a small fraction of the heritability of metabolic traits can be explained by cumulative mQTL. The remainder of the heritability indicates that variation is either due to a few, relatively new, highly deleterious variants, which is unlikely because they would be quickly removed by natural selection, or by many small variants that are not likely to be removed via natural selection. Regardless of how many genes are causing this heritability, it implies that spontaneous mutations are playing a role. Here we will employ C. elegans to analyze the relationship between the cumulative effects of spontaneous mutation on adenosine metabolism and on the function of the associated enzymes. The goals of this project are (1) to associate the effects of spontaneous mutations with variation in the metabolome and (2) quantify the covariance between the activity and concentration of metabolic enzymes in the adenosine pathway and metabolic phenotypes. We will also attempt to correlate mutational and network statistics for those metabolites in the adenosine pathway. Pilot data from four mutation accumulation (MA) lines and their common ancestor (N2) show significant variance for adenosine deaminase activity and concentration, adenosine kinase activity and concentration, as well as concentration of several metabolites in the adenosine pathway.
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[
International Worm Meeting,
2017]
A functional metabolic network is key for an organism's survival, and thus for its fitness. Spontaneous mutations reduce fitness, so it stands to reason they affect metabolism in some way. However, not all metabolites are equally important in maintaining organismal function, and the relationship between mutation and an organism's metabolic network has rarely been investigated. By investigating a set of mutation accumulation(MA) lines of Caenorhabditis elegans, we aim to better understand the effect mutations have on the metabolic network. Using a set of 43 MA lines and their ancestor, a pool of 29 metabolites was measured for changes in mean metabolite concentration (?M) and mutational variance (VM). We constructed a metabolic network map of these metabolites for C. elegans from the KEGG database, with the aim of characterizing the relationship between VM, ?M, and heritability found for these 29 metabolites and features of the metabolic network. Initial analysis shows a positive association between the largest k-core grouping of a metabolite and ?M and VM.
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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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[
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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[
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.
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Sedore, Christine A, Phillips, Patrick C, Coleman-Hulbert, Anna L, Driscoll, Monica, Banse, Stephan A, Lithgow, Gordon J, Guo, Max, Johnson, Erik
[
MicroPubl Biol,
2019]
The authors, Coleman-Hulbert, AL; Johnson, E; Sedore, CA; Banse, SA; Guo, M2; Driscoll, M3; Lithgow, GJ; and Phillips, PC, submit the following correction.
The first reference in the methods paragraph should be (Lucanic et al., 2017; Plummer et al., 2017) and should not be letteredaccordingly.
We assayed lifespan in response to imatinib mesylate exposure in three Caenorhabditis species in triplicate using our previously published workflow (Lucanic et al. 2017a; b).
should be corrected to:
We assayed lifespan in response to imatinib mesylate exposure in three Caenorhabditis species in triplicate using our previously published workflow (Lucanic et al., 2017; Plummer et al., 2017).
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Johnson, Lindsay, Andersen, Erik, Saxena, Ayush, Baer, Charles, Tanny, Robyn, Crombie, Timothy, Ponciano, Jose Miguel, Rajaei, Moein
[
International Worm Meeting,
2021]
The distribution of fitness effects (DFE) of new mutations is a fundamental parameter in population genetics, and has practical application in the context of modeling the genetic basis of complex heritable disease in humans. However, the DFE is very difficult to estimate empirically. At present, nearly all estimates of the DFE rely on either statistical inference from the standing site-frequency spectrum or from laboratory estimates of fitness in mutation accumulation (MA) lines, with no reference to the underlying specific mutations. We report results from a new method to estimate the DFE from competitive fitness data from a set of recombinant inbred lines (RILs) derived from a cross between two C. elegans MA lines, combined with whole-genome sequence data from the set of >500 RILs and the parental lines, as well as from ~40 fully-sequenced MA lines. Of five distributions fit to the data, all produce similar results, but the best fit is to a normal distribution nearly centered at 0, with almost no weight beyond +/- 2%. Averaged over two fitness assays, nearly ten years apart, the average fitness effect of a new mutation is about -0.2%. These results are in strong contrast with estimates of the average mutational effect inferred from MA line fitness data not informed by sequence data, which are much larger. We suspect that a few mutations of large effect may have been lost during the inbreeding phase of the construction of the RILs.
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[
Exp Gerontol,
2013]
This communication will briefly review more than 30 years of research on aging using the nematode Caenorhabditis elegans ("The Worm") as carried out in the labs of Tom Johnson. We will highlight research directions initiated in the 1980's, which were exciting for those of us trying to turn over a new leaf in aging research. In this narrative, I will discuss primarily the science that I and my lab have been involved with for the last 30 years. This area has been fascinating to those studying the sociology of science as modern aging research has moved to replace the simplistic, poorly controlled and outright fictitious approaches seen in much of the previous aging research.