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[
Mol Genet Genomics,
2002]
Mutations in the Drosophila miniature-dusky ( m-dy) gene complex were first reported by Morgan and Bridges about 90 years ago. m-dy mutants have abnormally small wings, a phenotype attributed to a cell-autonomous reduction in the size of the epidermal cells comprising the differentiated wing. Using a molecular genetic approach, we have characterized the m-dy chromosomal interval and identified a pair of adjacent transcription units corresponding to m and dy. A dy mutant known as dy (And) has a single base substitution within the protein-coding region that is predicted to result in an amber stop codon and premature translational termination. We show that dy mRNA is expressed at two discrete periods during the life cycle - one during embryonic development and early larval instars, the second during adult development, coincident with wing differentiation. In agreement with the phenotypic similarity of m and dy mutants, sequence comparisons reveal a similarity between the predicted MINIATURE and DUSKY proteins, and indicate that the m and dy genes are members of a larger Drosophila gene family. Both m and dy, as well as other members of this superfamily, are predicted to encode transmembrane proteins with similarity to C. elegans cuticle proteins known as cuticulins. We postulate that m, dy and other members of this protein superfamily function as structural components of the Drosophila cuticulin layer. Such a role for m and dy products in wing differentiation is sufficient to explain the morphological phenotypes associated with m-dy mutants.
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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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[
Development & Evolution Meeting,
2006]
Proper control of cell proliferation is critical for normal development. While the molecular basis for the proliferation/differentiation decision is relatively well-characterized in certain developmental contexts, less is known about cell-cell interactions that control of the extent of proliferation within a developing organ.
The C. elegans germ line offers a tractable model system for exploring this problem. Previous work (McCarter et al., 1997; Killian and Hubbard, 2005), indicates that the distal pair of somatic gonadal sheath cells (Sh1) promote robust larval germline proliferation. We are taking several approaches to identify the molecular basis for this interaction. Forward genetic screens, molecular analysis and directed RNAi studies identified a critical role for optimal ribosome biogenesis in the sheath (Killian and Hubbard, 2004; Voutev et al., submitted) for its germline proliferation-promoting activity. To identify additional players, a genome-wide RNAi screen and candidate screens are underway. One screening strategy is based on the observation that reduced larval germline proliferation inhibits gonad arm extension, delays meiotic entry, and thereby uncouples the coordination between somatic gonad and germline development. As a result, under certain conditions, reducing larval germline proliferation can enhance proximal germline tumor formation (Pro phenotype; Killian and Hubbard, 2005; see also abstract by Maciejowski and Hubbard). Thus we are screening for soma-autonomous RNAi-induced enhancers of Pro. In addition, candidate screens suggest that the insulin pathway contributes to robust larval germline proliferation.
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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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[
International Worm Meeting,
2011]
Cyclophilin D (CyPD), a mitochondrial matrix protein, has been widely studied for its diverse role in mitochondria physiological mechanism. We previously established in this laboratory that overexpression of CyPD in stable HEK cell lines, increased cell survival under oxidative stress conditions. For further investigation, integrated overexpression of CyPD was achieved in Caenorhabditis elegans and lifespan analysis has shown that they are long lived. To understand the mechanism of CyPD in longevity, ROS (reactive oxygen species) production and mitochondrial membrane potential (DY) were measured throughout the life of the animal using confocal microscopy. ROS was imaged using Mitosox (a superoxide indicator) and DY was imaged using TMRM (mitochondria potential indicator), in the mitochondria rich organ, the pharynx. Measurements, at various times in the worm's lifespan gave us surprising results. We found that transgenic long lived nematodes have higher rates of superoxide production and have higher mitochondrial membrane potentials. The oxidative stress theory of aging states that more ROS production would limit lifespan as a result of accumulation of damage over time. Our data speaks to the contrary and suggest that ROS production is not an appropriate indicator for lifespan. This new data about ROS corresponds with other aging researchers finding that ROS may have a more complex role in aging than previously suggested. More importantly, the functional consequences of CyPD overexpression in an organism, have never indicated a role in longevity. CyPD's role in aging pathology will add new understanding to CypD's unique role in the mitochondria.
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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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[
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.