Ritch, James J. et al. (2011) International Worm Meeting "Hunting for new genes that function in neuronal maintenance."

Ritch, James J., Thackeray, Andrea, DeGroot, Steven, Benard, Claire

[International Worm Meeting, 2011]

Maintenance factors ensure that neuronal structures, connectivity and function are preserved throughout life, well after their establishment earlier during development. A number of molecules are dedicated to maintain the precise position of neuronal soma, axons and dendrites in the face of the wear and tear of body movements. Two of these molecules are ZIG-5 and ZIG-8, which are secreted two-Ig domain proteins that we have found to function redundantly in maintenance. Numerous related molecules exist in mammals, many of which are expressed in the adult mouse brain, but their function is not understood. While zig-5 zig-8 double mutant animals develop normally, they later exhibit progressive displacement of head neurons ASH and ASI from the L4 stage onwards, and axon flip-over defects in the ventral nerve cord. The biochemical role of ZIG-5 and ZIG-8 is unknown, but our genetic analysis indicates that they interact with SAX-7, the C. elegans ortholog of the L1CAM family of vertebrate adhesion molecules that have been implicated in multiple human neurological disorders. The phenotype of zig-5 zig-8 is very similar to that of sax-7 null mutants, suggesting they may have related roles in maintenance. Moreover, loss of the sax-7 long isoform suppresses the zig-5 zig-8 mutant phenotypes. To elucidate the roles of zig-5 zig-8 in neuronal maintenance, we are hunting for additional genes that interact with zig-5 and zig-8. We are carrying out a modifier screen to identify genes involved in promoting neuronal maintenance (enhancers) as well as those that antagonize it (suppressors). Progress on the screen will be presented.

James J Collins et al. (2005) International Worm Meeting "A genetic screen to characterize anticonvulsant mediated lifespan extension in C. elegans"

Kerry Kornfeld, James J Collins, Kimberley J Evason

[International Worm Meeting, 2005]

The succinimide based anticonvulsant compounds ethosuximde and trimethadione are capable of extending C. elegans lifespan and delaying aging related functional declines. These compounds were able to extend the lifespan of daf-16 mutants, suggesting a daf-16 independent mechanism of lifespan extension. To further analyze how these drugs extend lifespan, we are identifying genes that mediate the effects of these drugs. Ethosuximide and trimethadione cause optimal lifespan extension at external concentrations of about 2 mg/ml, and cause a fully penetrant lethal phenotype at about 12 mg/ml. We screened for chemically induced mutations that enable animals to survive exposure to toxic doses of ethosuximide and trimethadione. We screened about 270,000 haploid genomes and identified 52 resistant mutants. Several of these mutants have now been backcrossed and analyzed for lifespan in the presence and absence of the drugs. Some of these mutants are partially or completely resistant to the lifespan extension caused by the drugs, indicating that the effected gene plays a role in regulating lifespan.

Doyle, James J. et al. (2019) International Worm Meeting "Muscle degeneration precedes neurodegeneration in a C. elegans models of spinal muscular atrophy."

Doyle, James J., Maios, Claudia, Parker, J. Alex, Patten, Shunmoogum, Vrancx, Celine, Labarre, Audrey

[International Worm Meeting, 2019]

Spinal muscular atrophy is (SMA) is a devastating, autosomal recessive neuromuscular disease resulting in muscle atrophy and neurodegeneration, and it is the leading genetic cause of infant death. SMA arises when there are homozygous deletion mutations in the human SMN1 gene, leading to a decrease in corresponding SMN1 protein. Although SMN1 is expressed across multiple tissue types, much of the previous research into SMA focused on the neuronal aspect of the disease, overlooking many of the potential non-neuronal aspects of the disease. Therefore, we sought to address this gap in knowledge by modeling SMA in the nematode Caenorhabditis elegans. We used a previously uncharacterized allele which resulted in the onset of mild SMA-like phenotypes allowing us to monitor the onset of phenotypes at different stages. We observed that these mutant animals recapitulated many key features of the human disease, and most importantly, we observed that muscle dysfunction precedes neurodegeneration. Furthermore, we tested the therapeutic efficacy of targeting endoplasmic reticulum (ER) stress in non-neuronal cells and found it to be more effective than targeting ER stress in neuronal cells. We also found that the most potent therapeutic potential came from a combination of ER- and neuromuscular junction (NMJ)-targeting drugs. Together, our results suggest an important non-neuronal component of SMA pathology and highlights new considerations for therapeutic intervention.

James J Moresco et al. (2001) International C. elegans Meeting "EGL-47 is a putative G protein-coupled receptor that controls egg-laying behavior"

James J Moresco, Michael R Koelle

[International C. elegans Meeting, 2001]

A screen to identify mutations that effect the functioning of the neurons that control egg-laying identified five genes, egl-10, egl-42, egl-47, egl-49 and egl-50 (Desai and Horviz, 1989). Mutants in these genes are egg-laying defective and insensitive to the serotonin reuptake inhibitor imiprimine, while having an anatomically normal egg-laying system, and normal sensitivity to serotonin. These characteristics are thought to result from functional defects in the HSN neurons that control egg laying. EGL-10 has been identified as a regulator of G protein signaling (RGS) protein, while the remaining genes have not been cloned. We chose to focus on egl-47 as it has the strongest egg laying defective phenotype. egl-47 is defined by two independently isolated dominant alleles n1081dm and n1082dm . Two intragenic revertents of n1082dm have a wild-type phenotype. High resolution mapping using single nucleotide polymorphisms (SNPs) from the strain CB4856 identified a 97 kb interval on chromosome V containing egl-47 . A PCR product generated from n1081dm from within this interval and containing only one predicted ORF, C50H2.2, was able to confer the Egl phenotype when transformed into wild-type worms, suggesting C50H2.2 is egl-47 . Comparable PCR products generated from wild-type worms and injected at higher concentrations were also able to confer the Egl phenotype to wild-type worms. This demonstrates that the dominant egl-47 alleles cause a gain of normal EGL-47 function. 5' RACE revealed that egl-47 uses two promoters and generates transcripts encoding proteins with different N termini and a common C terminus. The common C terminus appears to contain seven transmembrane spanning domains, suggesting egl-47 encodes two G protein-coupled receptors. Sequencing of the dominant alleles revealed an alanine to valine mutation in a putative transmembrane domain. The same base change is present in both dominant alleles. The two revertant alleles contain additional missense mutations. An Alanine to Valine mutation in a transmembrane domain of a G protein-coupled receptor commonly constitutively activates the receptor. Perhaps constitutively active EGL-47 leads to an increase in signaling through the G alpha protein GOA-1, which inhibits egg laying. We have isolated a null allele of egl-47 by screening a library of deletion mutants. We are currently characterizing egl-47 , using both gain and loss of function alleles in epistasis experiments with known G protein signaling mutants. We are analyzing the localization of EGL-47 to determine if this protein is involved in the function of the HSN. Reference Desai, C. and Horvitz, H.R. (1989). Genetics, 121:703-721.

Collins, James J. et al. (2009) International Worm Meeting "The anticonvulsant ethosuximide disrupts sensory function to extend C. elegans life span."

Kornfeld, Kerry, Collins, James J., Pickett, Christopher L., Schneider, Daniel L., Evason, Kimberley

[International Worm Meeting, 2009]

Ethosuximide is a medication used to treat seizure disorders in humans. We previously demonstrated that ethosuximide could delay age-related changes and extend the life span of C. elegans. The mechanism of action of ethosuximide in life span extension is unknown, and elucidating how ethosuximide functions is important for defining endogenous processes that influence life span and for exploring the potential of ethosuximide as a therapeutic for age-related diseases. To identify factors that mediate the activity of ethosuximide, we conducted a genetic screen and identified mutations in two genes, che-3 and osm-3, that confer resistance to ethosuximide-mediated toxicity. Mutations in che-3 and osm-3 cause defects in an overlapping set of chemosensory neurons, resulting in defective chemosensation and life span extension. These findings suggest that ethosuximide extends life span by inhibiting the function of specific chemosensory neurons. This model is supported by the observation that ethosuximide treated animals displayed numerous phenotypic similarities with mutants that have chemosensory defects. Furthermore, long-lived osm-3 animals were resistant to the life span extension caused by ethosuximide, suggesting the drug extends life span by inhibiting chemosensation. These studies demonstrate a novel mechanism of action for a life span extending drug and indicate that sensory perception has a critical role in controlling life span. Sensory perception also influences the life span of Drosophila, suggesting that sensory perception has an evolutionarily conserved role in life span control. These studies highlight the potential of ethosuximide and related drugs that modulate sensory perception to extend life span in diverse animals.

Christopher J James et al. (2009) European Worm Neurobiology Meeting "On tracking the behaviour of C. elegans using a novel GMM based video analysis algorithm"

Christopher J James, James Dillon, Vincent OConnor, Lindy Holden-Dye

[European Worm Neurobiology Meeting, 2009]

Tracking the behaviour of C. elegans through the analysis of video recordings provides an objective technique to define the impact of mutations and experimental paradigms on patterns of locomotor activity. We introduce a novel technique to detect and track single worms from digitised videos on a frame by frame basis. The system first isolates and detects the presence of a worm on a single digitised frame. A parameterised worm is then obtained by identifying N nodes, the co-ordinates of which are such that they align themselves to the midline along the worm. The N node centres together form a Gaussian Mixture Model (GMM) and are obtained following an adaptive process using the Expectation Maximisation (EM) algorithm. The whole process is repeated on each new frame, where the final positions of the nodes in the previous frame are used to initialise the EM algorithm for the new frame, and so on. As a consequence of the small number of nodes needed to parameterise the worm, the algorithm converges in around 20 iterations on average for each frame, making the algorithm extremely efficient. Once the entire video of T frames is processed it is then possible to assess worm behaviour through analysing the N.T dimensional worm time-series. The method has been trialled on worms subjected to different ethanol-induced behavioural states and provides parameters that robustly distinguish between behaviour in intoxication and ethanol withdrawal. Further refinement of the approach is in progress to enable the parameterisation of distinct behavioural subroutines underpinned by defined neural microcircuits, thus facilitating the genetic dissection of the neural substrates of behaviour.

Butler JA et al. (1994) Worm Breeder's Gazette "Looking For Extracellular Matrix Proteinases in C. elegans"

Kramer JM, Butler JA

[Worm Breeder's Gazette, 1994]

LOOKING FOR EXTRACELLULAR MATRIX PROTEINASES IN C. ELEGANS. James A. Butler and James M. Kramer, Northwestern University Medical School. Department of CMS Biology, Chicago IL 60611

Wissmann AK et al. (1994) Worm Breeder's Gazette "Characterization of the let-502 Gene"

Mains PE, Wissmann AK, McGhee JD

[Worm Breeder's Gazette, 1994]

Characterization of the let-502 gene Andreas Wissmann, James D. McGhee and Paul E. Mains, Dept. of Medical Biochemistry, University of Calgary, Calgary, Alberta, Canada T2N 4N1

McGhee JD (1987) Biochemistry "Purification and characterization of a carboxylesterase from the intestine of the nematode Caenorhabditis elegans."

McGhee JD

[Biochemistry, 1987]

The major intestinal esterase from the nematode Caenorhabditis elegans has been purified to essential homogeneity. Starting from whole worms, the overall purification is 9000-fold with a 10% recovery of activity. The esterase is a single polypeptide chain of Mr 60,000 and is stoichiometrically inhibited by organophosphates. Substrate preferences and inhibition patterns classify the enzyme as a carboxylesterase (EC 3.1.1.1), but the physiological function is unknown. The sequence of 13 amino acid residues at the esterase N- terminus has been determined. This partial sequence shows a surprisingly high degree of similarity to the N-terminal sequence of two carboxylesterases recently isolated from Drosophila mojavensis [Pen, J., van Beeumen, J., & Beintema, J. J. (1986) Biochem. J. 238, 691-699].

Murakami S et al. (1999) Curr Biol "Life extension and stress resistance in Caenorhabditis elegans modulated by the tkr-1 gene."

Johnson TE, Murakami S

[Curr Biol, 1999]

In this Brief Communication, which appeared in the 14 September 1998 issue of Current Biology, the UV dose was reported erroneously. The dose reported was 20 J/m2 but the actual dose used was 0.4 J/cm2. Also, the gene formally referred to as tkr-1 has since been renamed old-1 (overexpression longevity determination).