Stasiuk, Susan J et al. (2013) International Worm Meeting "Metabolism of benzimidazole anthelmintics in Caenorhabditis elegans, and the ruminant parasite, Haemonchus contortus."

Gilleard, John S, Ro, Dae-Qyun, Stasiuk, Susan J, MacNevin, Gillian

[International Worm Meeting, 2013]

Widespread anthelmintic resistance among animal parasites and concerns regarding its emergence among human parasites makes the understanding of how parasites metabolize and eliminate anthelmintics an important goal. We have previously shown that albendazole, an anthelmintic commonly used in humans and livestock, is metabolized to a glucoside derivative in C. elegans. Glycation of drugs is rare in mammals and had not been previously reported for the benzimidazoles. We have investigated whether other members of the benzimidazole (BZ) family were also glycosylated in C. elegans and in H. contortus, a parasitic nematode that is a model for anthelmintic drug discovery and resistance research. Using HPLC and LC/MS we have characterised the metabolites produced by C. elegans following exposure to albendazole, mebendazole, thiabendazole, oxfenbendazole, and fenbendazole. Each of the BZ were modified by the addition of a glucose ( plus or minus other) moiety. This glycation appears to be nematode specific, since mammals have been shown to metabolize these substances by sulfo-conjugation reactions only. Furthermore, the metabolites were found mainly in the media suggesting they are efficiently eliminated from the worms. We have shown that the parasite H. contortus metabolizes the BZs to the same glucoside derivatives as C. elegans. One approach to identifying the enzymes responsible for the metabolism is to examine the transcriptomic response. We have shown earlier that a small number of C. elegans genes are up-regulated in response to albendazole (including cyp-35C1, cyp-35A2, cyp-35A5, ugt-16, ugt-63 and gst-5). We have tested the specificity of this response using QRT-PCR and have found that these genes were up-regulated by the other BZs, although the relative levels of up-regulation differed between drugs. By manipulating the expression levels of these genes in C. elegans we will test the effect on BZ metabolism and potency. In summary, metabolism of BZs differ dramatically between mammals and nematodes but is very similar in C. elegans and H. contortus suggesting C. elegans is a valid model for the functional analysis of these processes in strongylid parasites.

Susan Stasiuk et al. (2007) First Australian C. elegans Meeting "The Insulin/IGF signalling transduction pathway in Parastrongyloides trichosuri, does it play a role in parasitism and ageing?"

Susan Stasiuk, Warwick Grant.

[First Australian C. elegans Meeting, 2007]

Parastrongyloides trichosuri is an intestinal parasite of the Australian brush-tailed possum (Trichosuris vulpecula). In the early L1 stage, P. trichosuri make a developmental choice to become either a short lived, free-living nematode or a long lived parasite. We show that this developmental choice appears to be triggered by environmental signals such as temperature, food availability and population density , all known to be factors which influence entry of C. elegans into the dauer pathway. (daumone). We also report that free-living P. trichosuri excrete a factor which is the primary mediator of the switch from free-living to parasitic development and that this factor most likely also influences the lifespan of the free-living form of this species. We hypothesise that this factor is analogous to C. elegans dauermone.. In C. elegans, daumone is believed to influence the signalling state of the Insulin/IGF signalling pathway, the end result of which is to initiate either normal adult development or diapause entry. Furthermore, mutation of some genes of the Insulin/IGF signal transduction pathway confer a 3-5 fold extension in C. elegans lifespan. The key genes involved in the Insulin/IGF pathway are the putative IGF-receptor, daf-2; the phosphatidylinositol 3-OH kinase, age-1 and the forkhead transcription factor, daf-16. We have cloned the putative orthologues of these components of the Insulin/IGF signalling pathway from P .trichosuri and aim to test the role that these Insulin/IGF signalling pathway gene orthologues may play in P. trichosuri ageing and development.. Since the unusual life history of P. trichosuri includes a completely free-living life cycle, we are able to maintain this species indefinitely in the laboratory as a free-living nematode. It is therefore amenable to manipulation using both classical genetic and molecular genetic techniques (see Grant et al., this meeting). Under the correct environmental conditions, it can then be switched into the parasitic life cycle. P. trichosuri therefore presents us with the opportunity to study an organism where aging and developmental plasticity are the result of a natural developmental choice and differential gene expression, rather then the result of knockdown or mutation of genes. This may allow for the opportunity to discover novel longevity genes that are silent in the model systems currently used.

Susan J. Stasiuk et al. (2007) International Worm Meeting "The Insulin/IGF signalling transduction pathway in Parastrongyloides trichosuri, does it play a role in parasitism and aging?"

Susan J. Stasiuk, Warwick Grant

[International Worm Meeting, 2007]

Parastrongyloides trichosuri is an intestinal parasite of the Australian brush-tailed possum (Trichosuris vulpecula). In the early L1 stage, P. trichosuri make a developmental choice to become either a short lived, free-living nematode or a long lived parasite. We show that this developmental choice appears to be triggered by environmental signals such as temperature, food availability and population density, all known to be factors which influence entry of C. elegans into the dauer pathway. (daumone). We also report that free-living P. trichosuri excrete a factor which is the primary mediator of the switch from free-living to parasitic development and that this factor most likely also influences the lifespan of the free-living form of this species. We hypothesise that this factor is analogous to C. elegans daumone. In C. elegans, daumone is believed to influence the signalling state of the Insulin/IGF signalling pathway, the end result of which is to initiate either normal adult development or diapause entry. Furthermore, mutations of some genes of the Insulin/IGF signal transduction pathway confer a 3-5 fold extension in C. elegans lifespan. The key genes involved in the Insulin/IGF pathway are the putative IGF-receptor, daf-2; the phosphatidylinositol 3-OH kinase, age-1 and the forkhead transcription factor, daf-16. We have cloned the putative orthologues of these components of the Insulin/IGF signalling pathway from P. trichosuri and aim to test the role that these Insulin/IGF signalling pathway gene orthologues may play in P. trichosuri ageing and development. Since the unusual life history of P. trichosuri includes a completely free-living life cycle, we are able to maintain this species indefinitely in the laboratory as a free-living nematode. It is therefore amenable to manipulation using both classical genetic and molecular genetic techniques (see Grant et al., this meeting). Under the correct environmental conditions, it can then be switched into the parasitic life cycle. P. trichosuri therefore presents us with the opportunity to study an organism where aging and developmental plascity are the result of a natural developmental choice and differential gene expression, rather then the result of knockdown or mutation of genes. This may allow for the opportunity to discover novel longevity genes that are silent in the model systems currently used.

Maartens A (2018) Development "An interview with Susan Strome."

Maartens A

[Development, 2018]

Susan Strome is Distinguished Professor of Molecular, Cell and Developmental Biology at the University of California, Santa Cruz, USA. Recently appointed an editor at Development, her lab studies the regulation of germ cell development in<i>C. elegans</i>, with a particular focus on the epigenetic transmission of chromatin states. We caught up with Susan to discuss her early career switch from prokaryotes to worms, her experiences of small and big science, and why teaching is so important to her.

Latheef, Sharmilah L.J. et al. (2013) International Worm Meeting "The use of C.elegans to identify novel mutations that confer benzimidazole resistance."

Latheef, Sharmilah L.J., Gilleard, John S., Stasiuk, Susan S.

[International Worm Meeting, 2013]

Parasitic nematodes are a huge threat to the livestock industry as well as human health. Livestock infections cause billions of dollars in production loss per annum whilst infections in humans are a leading cause of disability and poverty especially in the developing world. Intensive use of the limited number of anthelmintics available for the treatment of parasitic nematode infections in livestock has resulted in the widespread development of resistance in many regions of the world. The recent increase in community-wide anthelmintic treatment programs in humans in the developing world-using the same drug classes used in livestock- is raising concerns of similar emergence of resistance in human parasites. Hence, there is an urgent need to understand the causal mechanisms of resistance and develop new diagnostic tests and control measures. Benzimidazoles (BZ) are an important drug class for both human and animal parasite control. It is known that amino acid substitutions in the isotype-1 b-tubulin drug target at positions 167, 198 and 200 can prevent drug binding and lead to drug resistance in several parasitic livestock species. The major objective of this project is to identify additional novel causal mutations of BZ resistance using the natural genetic variation found in wild C.elegans populations. The effect of albendazole on the motility of 16 natural C.elegans isolates was tested and two strains were identified that had a high level of resistance compared to the N2 strain. The ben-1 locus was sequenced in these two strains and a novel mutation resulting in an Alanine to Proline substitution at amino acid position 185 was found in one strain and a frame-shift in the other. The functional significance of the identified non-synonymous polymorphisms was confirmed by genetic complementation studies with the ben-1(e1880) reference strain. Hence, we have identified naturally occurring strains with a high level of resistance to BZ drugs which leads to questions regarding the role of environmental pollution as a selective force. We've also identified a previously unreported amino acid substitution in the ben-1 locus that is capable of conferring resistance which has yet to be reported in parasitic nematodes.

Jean, Francesca et al. (2021) International Worm Meeting "Using WGS to identify intragenic suppressors of zyg-1 in Caenorhabditis elegans reveals the importance of genomic context in phenotypic interpretation"

Stasiuk, Susan, Tarailo-Graovac, Maja, Galbraith, Andrew, Jean, Francesca, Maroilley, Tatiana

[International Worm Meeting, 2021]

Intragenic modifiers can have dramatic effects on phenotypic outcomes, and in disease, can affect attributes such as severity or age of onset. However, the focus of many modifier screens in model systems is the identification and interpretation of extragenic variants rather than understanding the link between intragenic modifiers and phenotype. Accordingly, technological advances in the field, such as the use of whole-genome sequencing (WGS) or CRISPR, tend to be reserved for the discovery and interpretation of extragenic variants, whereas intragenic modifiers still rely on more traditional methods, such as PCR and Sanger sequencing. We demonstrate that intragenic modifier discovery and interpretation following modifier screens benefits greatly from WGS and CRISPR technologies by subjecting strains generated from a chemical mutagenesis suppressor screen using a temperature-sensitive zyg-1(it25) allele to WGS, filtering for intragenic variants using an in-house pipeline, and validating with CRISPR and homology-directed repair. Following this method, we rapidly identify that approximately 10% of our strains contain intragenic zyg-1 variants. By re-creating the intragenic variants in the parental strain, we show that most intragenic variants suppress the original phenotype, but this is not universal. Based on this, we encourage extending variant validation using CRISPR to intragenic variants to determine whether they are truly capable of modifying the original primary variant and to what extent. For those intragenic variants that are capable of suppressing, the position of the variant in comparison to the original primary variant matters; closer modifying variants are more likely to be true suppressors and have a higher suppression ability, which has important implications in understanding complex alleles in disease. Finally, genomic context, as provided by WGS, plays an important role in our interpretation of the contribution of the variant to suppression dynamics. For instance, several of the strains contain extragenic variants that, in addition to the intragenic variant, are proposed to enhance suppression. In contrast, we identified a strain with substantial genetic burden, dampening the suppression ability of the intragenic variant. Altogether, this work describes a methodology for the high-throughput identification of intragenic modifiers and highlights the importance of thoroughly understanding the phenotypic contribution of intragenic modifiers.

Maroilley, Tatiana et al. (2021) International Worm Meeting "Characterizing complex genomic rearrangements in C. elegans using short-read Whole Genome Sequencing"

Maroilley, Tatiana, Tarailo-Graovac, Maja, Li, Xiao, Oldach, Matthew, Jean, Francesca, Stasiuk, Susan

[International Worm Meeting, 2021]

Structural variants (SVs) and complex rearrangements are a significant, but understudied, part of genomic natural diversity. They can also result in various phenotypes in Caenorhabditis elegans. Additionally, certain strains, known as balancers, carry various types of spontaneous or induced (X-rays, gamma irradiation, chemical mutagens, or more recently CRISPR-Cas9) chromosomal rearrangements. Because those rearrangements abolish or reduce crossover events between large portions of the C. elegans genome, balancers have been used for decades to maintain lethal mutations, facilitate strain construction, or capture mutations. However, despite the advent of sequencing technologies, detecting SVs and complex rearrangements is challenging and thus, in most mutagen-induced balancers, the chromosomal rearrangements have not been characterized at the molecular level. High-throughput WGS sequencing, based on short-reads (srWGS), is the most economical, accurate, and widely supported technology at this time. Yet, the length of short-reads is often reported as limiting the detection of complex genetic events. Long-read technologies are then recommended as an alternative despite their increased costs. Here, we applied srWGS alongside tailored bioinformatics approaches to unravel complex genomic rearrangements in several C. elegans balancer genomes. Our method successfully identified complex balancer rearrangements such as reciprocal translocation (eT1), large deletion (eDf43), chromosome fusion (sC4), and free duplication (sDp3). We were also able to identify and experimentally confirm several chromoanagenesis events. Therefore, our results show that we can maximize the possibilities of srWGS by implementing meticulous analytical approaches. Higher confidence in complex variant calls from srWGS will help to molecularly characterize C. elegans balancers and in the future, to decipher the full spectrum of natural genetic variation in C. elegans.

Gasser SM (2022) Epigenomics "Lessons in chromatin organization and gender equity in research: an interview with Susan Gasser."

Gasser SM

[Epigenomics, 2022]

In this interview, Professor Susan Gasser speaks with Storm Johnson, commissioning editor for <i>Epigenomics</i>, on her research on genome stability, epigenetic regulation and chromatin organization, as well as her work supporting women in research. Susan Gasser completed her BA at the University of Chicago, with an honors thesis in biophysics, and her PhD in biochemistry at the University of Basel in 1982, with Gottfried Schatz. She was a postdoc with Ulrich Laemmli at the University of Geneva, which initiated her career-long interest in chromosomes and chromatin structure. She established her own laboratory at the Swiss Institute for Experimental Cancer Research (ISREC) in 1986, focusing on chromatin organization in budding yeast, combining genetics, microscopy and biochemical approaches to understanding silent chromatin and telomeres. In 2001, she was named professor of molecular biology at the University of Geneva and expanded her laboratory's pioneering use of high-resolution time-lapse fluorescence microscopy to study single locus dynamics in the nucleus. From 2004 to 2019, Susan was the Director of the Friedrich Miescher Institute for Biomedical Research in Basel, where she also led a research group until the end of 2020. In Basel, she extended her research interests into heterochromatin in <i>Caenorhabditiselegans</i>. Her laboratory identified the mechanisms that position tissue-specific genesin the nuclei ofembryos and ofdifferentiated tissues, combining high throughput molecular analyses with cell biology to determine structure-function relationships in chromatin. Since January 2021, Susan Gasser has been <i>professor invite</i> at the University of Lausanne and Director of the ISREC Foundation, where she is helping shape the new Agora Institute of Translational Cancer Research. She was elected to the Academie de France, Leopoldina, European Molecular Biology Organization (EMBO), American Association for the Advancement of Science and Swiss Academy of Medical Sciences, and she received the French National Institute of Health and Medical Research (INSERM) International Prize in 2011, the Federation of European Biochemical Societies | EMBO Women in Science Award in 2012, the Weizmann Institute Women in Science Award in 2013 and honorary doctorates from the University of Lausanne, the University of Fribourg and Charles University in Prague. In Switzerland, she was the recipient of the Friedrich Miescher Award, the National Latsis Prize and the Otto Naegeli Award for the promotion of medical research. She participates in numerous review boards and advisory committees in Switzerland, across Europe and in Japan; she currently serves on the governing board of the Swiss Federal Institutes of Technology and the Swiss Science Council. From 2000 to 2004, she was vice chairperson, then chairperson of the EMBO Council. Susan led the Gender Committee of the Swiss National Science Foundation from 2014 to 2019 and initiated the Swiss National Science FoundationPrima program for the Promotion of women in academia. She has actively promotedthe careers of women scientists in Europe and Japan.

Mango S (2009) Curr Biol "Q&A: Susan Mango."

Mango S

[Curr Biol, 2009]

Susan Mango is Benning Professor of Oncological Sciences at the University of Utah and an Investigator at the Huntsman Cancer Institute. She grew up in England and Washington D.C. before attending Harvard University. She received her Ph.D. from Princeton, where she studied the c-myc oncogene with Michael Cole. She was introduced to the nematode Caenorhabditis elegans as a postdoc with Judith Kimble at the University of Wisconsin - Madison, and moved to Utah in 1996 to start her own lab. After 13 years at the University of Utah, she will move to Harvard University in July 2009. Her principal focus is transcriptional strategies of organ development, using the C. elegans foregut as a model.

Morrison M et al. (1996) West Coast Worm Meeting "IDENTIFICATION OF POTENTIAL P-GRANULE COMPONENTS AND THEIR MOUSE HOMOLOGUES"

Morrison M, Roth MB

[West Coast Worm Meeting, 1996]

P-granules are cytoplasmic structures found in the germline. It has long been thought that p-granules may contain molecules important for germ cell function. To better understand the connection between p-granule components and germline function we have cloned and are characterizing gene products which are likely p-granule constituents. Using the monoclonal antibody k76 generated by Susan Strome and Bill Wood, which stains p-granules at all stages of germline development, we have identified cDNAs that encode potential antigens. Expression and reverse gentic analyses are in progress to learn whether the potential p-granule components play a role in germline function. In support of the idea that k76 antigens are involved in germline function we find that the antibody stains primary germ cells in the mouse testes. Mouse cDNAs isolated using the antibody show germline specific expression and homology with some of the worm cDNAs. These observations indicate that k76 antigens are conserved and perhaps share a common germline function in diverse animal species.