Loose, Julia et al. (2019) International Worm Meeting "Impact of Meiotic-Gene Mutations on Lifespan and Health Span."

Ghazi, Arjumand, Yanowitz, Judith, Patil, Thayjas, Loose, Julia

[International Worm Meeting, 2019]

While the connection between increased maternal age and fertility loss is well established, it is unclear how the decline in germline integrity impacts aging. In addition, the mechanisms governing how germline fidelity impacts fertility loss and somatic aging have not been elucidated. These questions are challenging to address through human studies and vertebrate models. We are utilizing Caenorhabditis elegans to address this relationship. We screened 35 mutants impacting genes involved in different stages of meiosis, a germline-restricted phenomenon, for lifespan phenotypes. We found 24 mutants to be significantly short lived. To analyze the impact of meiotic fidelity on health span, the qualitative measure of rate of aging, we are assessing various physiological and behavioral parameters that decline with age, including neural deficits, in meiotic-gene mutants. We employed a widely-used chemotaxis assay to measure how short-term associative memory (STAM) changes with age and in the presence of various meiotic mutations. Compared to the wild type, all meiotic mutants showed a decreased ability to retain STAM from young adulthood (Day 1) to middle age (Day 5). Overall, our data indicates that mutations that govern meiotic fidelity in the germline impact health span, specifically, cognitive performance with age. Future studies will examine the specific mechanisms by which meiotic integrity influences somatic aging.

Loose, Julia et al. (2021) International Worm Meeting "Meiotic mutations impact lifespan and healthspan in C. elegans"

Patil, Thayjas, Loose, Julia, Yanowitz, Judith, Ghazi, Arjumand

[International Worm Meeting, 2021]

Meiotic chromosomal defects increase with age and are a major cause of miscarriages and age-related fertility loss in women. The link between maternal age and fertility has been well studied, however it is unknown if, and, how germline integrity impacts the rate of aging of the whole organism. We are utilizing the nematode model Caenorhabditis elegans to address the causative role of germline health on somatic aging. Specifically, we have examined genes that govern meiotic fidelity in the germline and addressed their role in somatic aging. C. elegans is uniquely suited to address this question as the somatic cells in the adult organism are post mitotic, allowing us to selectively disrupt germline integrity through meiotic gene mutations. We found that 14 of the 38 mutations we examined, in genes that govern different steps of meiosis, significantly reduced the lifespan of the animal. We also found that germline-specific RNAi knockdown of selected meiotic gene candidates, spo-11, dsb-2, and htp-3, also reduced lifespan. These genes have roles throughout meiosis including double strand break formation during the process of meiotic recombination (spo-11 and dsb-2) and the formation of the synaptonemal complex (htp-3). We also examined how meiotic gene disruption impacts the rate of aging by measuring healthpsan parameters. We found mutations in all of the selected candidate meiotic genes, exhibited deficits in at least one, and often more than one, healthspan feature, including loss of mobility, diminished pharyngeal muscle pumping, tissue integrity and neurological function. Overall, our data demonstrate that genes that govern meiotic fidelity in the C. elegans germline impact the physiological health of the somatic tissues and aging of the whole organism.

Amrit, Francis RG et al. (2021) International Worm Meeting "TCER-1-regulated alternative splicing promotes stress resilience"

Ghazi, Arjumand, Amrit, Francis RG, KUROYANAGI, Hidehito, Loose, Julia, Pfenning, Andreas

[International Worm Meeting, 2021]

Alternative RNA splicing augments proteomic biodiversity in eukaryotes, and has an emerging role in regulating longevity. This process has been shown to have various roles based on physiological demands including those in response to external stimuli. Here, we show that in the nematode Caenorhabiditis elegans, exposure to the Gram-negative pathogen, Pseudomonas aeruginosa, induces a shift in alternative splicing. In vivo analysis of transgenic reporters of splicing fidelity showed significant splicing changes in multiple tissues. Based on our recent discovery that TCER-1, worm homolog of the human transcription elongation and splicing factor, TCERG1, represses innate immunity in worms, we examined the role of TCER-1 in the modulation of splicing upon pathogen exposure. tcer-1 mutants exhibited aberrant splicing regulation in multiple tissues, and transcriptomic analysis identified 54 exon-skipping and 468 intron retention events upon tcer-1 inactivation. In vivo analyses of these events revealed a TCER-1 dependent splicing pattern that correlated with our stress resilience phenotypes. Further, CRISPR-mediated recreation of alternative splicing observed in tcer-1 mutants enhanced immunoresistance and motor function. Together our findings bring to the forefront the important role of alternative splicing in stress resilience and healthspan, and reveal TCER-1- to be a major regulator of this process.

(2019) Development "The people behind the papers - Julia Brandt, Mary Rossillo and Niels Ringstad."

[Development, 2019]

A fundamental aim in developmental biology is to understand how the various cell types of the body are specified by differential gene regulation. <i>Caenorhabditis</i><i>elegans</i> nervous system development provides a powerful system for studying this, as exemplified by a new Development paper reporting on how the BAG neurons that help the worm sense oxygen and carbon dioxide are specified. We caught up with first authors Julia Brandt and Mary Rossillo and their supervisor Niels Ringstad (Associate Professor at the Skirball Institute of Biomolecular Medicine and Department of Cell Biology at New York University) to find out more about the story.

Kreis HA et al. (1933) Trans Am Microsc Soc "Two new species of Rhabditis (R macrocerca & R clavopapillata) assoc with dogs and monkeys in experimental Strongyloides studies."

Faust EC, Kreis HA

[Trans Am Microsc Soc, 1933]

From time to time during our studies on experimental Strongyloides infections, freshly passed stools of dogs have been contaminated with species of Rhabditis. At first it was believed that the contaminations resulted from improper sterilization of the Petri dishes used in collecting the feces, but after this possibility was eliminated the worms appeared with equal consistency. Sterilization of the cages in which the animals were housed also failed to reduce the contamination. Studies were then made of the animals themselves and it was found that the worms were developing in abundance among the perianal hairs, particularly in those dogs which had loose bowel movements. To a lesser extent the hairs of the abdomen, legs and even the face were also discovered to be favorable breeding places for these rhabditids. Thorough cleansing of the dogs externally with cresol solutions reduced the contamination appreciably but did not completely eliminate

Fields SD et al. (1998) J Cell Sci "The S. cerevisiae CLU1 and D. discoideum cluA genes are functional homologues that influence mitochondrial morphology and distribution."

Fields SD, Conrad MN, Clarke M

[J Cell Sci, 1998]

The cluA gene, encoding a novel 150 kDa protein, was recently characterized in Dictyostelium discoideum; disruption of cluA impaired cytokinesis and caused mitochondria to cluster at the cell center. The genome of Saccharomyces cerevisiae contains an open reading frame (CLU1) that encodes a protein that is 27% identical, 50% similar, to this Dictyostelium protein. Deletion of CLU1 from S. cerevisiae did not affect cell viability, growth properties, sporulation efficiency, or frequency of occurrence of cells lacking functional mitochondria. However, in clu1Delta cells the mitochondrial reticulum, which is normally highly branched, was condensed to one side of the cell. Transformation of cluA- Dictyostelium mutants with the yeast CLU1 gene yielded amoebae that divided normally and had dispersed mitochondria. The mitochondria in cluA- Dictyostelium cells complemented with CLU1 were not as widely scattered as in cluA+ Dictyostelium cells, but formed loose clusters throughout the cytoplasm. These results indicate that the products of the CLU1 and cluA genes, in spite of their limited homology, are functional homologues.

Peixoto CA et al. (1995) Tissue Cell "Freeze-fracture and deep-etched view of the cuticle of Caenorhabditis elegans."

Peixoto CA, DeSouza W

[Tissue Cell, 1995]

At ultrastructural level, the Caenorhabditis elegans (C. elegans) cuticle shows the presence of well-defined layers, one of them is a membrane-like structure designated as epicuticle, always present on the outermost surface of nematodes. Freeze-fracture replicas revealed the existance of two faces of the epicuticle: a inner face containing numerous particles, and a almost smooth outer face. Deep etching replicas confirmed the existance of these two faces of the epicuticle showing in some replicas two particle populations on the outer face of L4 and adult forms of C. elegans. Also a previously unrecognized structure was noted in the cuticle of C. elegans, a matrix composed by network of globular and filamentous structures, leaving in between them spaces, which probably are occupied by water in the living adult and L4 larvae specimen. This network demonstrates either a compact nature or loose nature according to their cuticle location. Deep etching replicas of the adults nematode revealed large spaces between the cortical and basal layers which are regularly interrupted by struts connecting each other by fibers in a particular arrangement.

Cordeddu V et al. (2009) Nat Genet "Mutation of SHOC2 promotes aberrant protein N-myristoylation and causes Noonan-like syndrome with loose anagen hair."

Tartaglia M, Cordeddu V, Tenconi R, Schackwitz W, Bazzicalupo P, Iyengar R, Cardinale A, Pennacchio LA, Bartholdi D, Ma'ayan A, Rossi C, Martinelli S, Selicorni A, Flex E, Cecchetti S, Zampino G, Digilio MC, Kutsche K, Lipzen A, Zenker M, Lepri F, Anichini C, Di Schiavi E, Dallapiccola B, Fodale V, Ferrero GB, Martin J, Sarkozy A, Gelb BD, Merlo D, Mazzanti L

[Nat Genet, 2009]

N-myristoylation is a common form of co-translational protein fatty acylation resulting from the attachment of myristate to a required N-terminal glycine residue. We show that aberrantly acquired N-myristoylation of SHOC2, a leucine-rich repeat-containing protein that positively modulates RAS-MAPK signal flow, underlies a clinically distinctive condition of the neuro-cardio-facial-cutaneous disorders family. Twenty-five subjects with a relatively consistent phenotype previously termed Noonan-like syndrome with loose anagen hair (MIM607721) shared the 4A&gt;G missense change in SHOC2 (producing an S2G amino acid substitution) that introduces an N-myristoylation site, resulting in aberrant targeting of SHOC2 to the plasma membrane and impaired translocation to the nucleus upon growth factor stimulation. Expression of SHOC2(S2G) in vitro enhanced MAPK activation in a cell type-specific fashion. Induction of SHOC2(S2G) in Caenorhabditis elegans engendered protruding vulva, a neomorphic phenotype previously associated with aberrant signaling. These results document the first example of an acquired N-terminal lipid modification of a protein causing human disease.

Ben Lehner et al. (2006) European Worm Meeting "Systematic Mapping of Genetic Interactions in C. elegans Suggests a New Paradigm for Human Genetic Disease"

Catriona Crombie, Andrew G. Fraser, Ben Lehner, Angelo Fortunato, Julia Tischler

[European Worm Meeting, 2006]

Ben Lehner, Catriona Crombie, Julia Tischler, Angelo Fortunato and Andrew G. Fraser Most heritable traits, including disease susceptibility, are affected by the interactions between multiple genes. However, we still understand very little about how genes interact since only a minute fraction of possible genetic interactions have been explored experimentally. To begin to address this, we are using RNA interference to identify genetic interactions in C. elegans, focussing on genes in signalling pathways that are mutated in human diseases. We tested ~65,000 pairs of genes for possible interactions and identify ~350 genetic interactions. This is the first systematically constructed genetic interaction map for any animal. We successfully rediscover most components of previously known signalling pathways; furthermore, we verify 9 novel modulators of EGF signalling. Crucially, our dataset also provides the first insight into the global structure of animal genetic interaction maps. Most strikingly, we identify a class of highly connected ''hub'' genes: inactivation of these genes greatly enhances phenotypes resulting from mutations in many different pathways. These hub genes all encode chromatin regulators, and their activity as genetic hubs appears conserved across metazoans. We propose that these genes function as general buffers of genetic variation and that these hub genes will act as modifier genes in multiple, mechanistically unrelated genetic diseases in humans.

Donnelly J L et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "Tyraminergic Inhibition of GABA Release Facilitates Turning Behavior in the C. elegans Escape Response"

Donnelly J L, Pirri J K, Alkema M J, Clark C M

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

Gentle anterior touch induces an escape response in which the nematode reverses, suppresses head oscillations, and is often followed by a deep ventral bend (omega turn), and reinitiation of forward locomotion in the opposite direction. Tyramine plays a key role in the C. elegans escape response. We have shown that the tyramine-gated chloride channel, LGC-55, coordinates the suppression of head oscillations and the long reversal during the initial phase of the escape response. In a genetic screen for mutants that are resistant to the paralytic effects of exogenous tyramine, we isolated alleles of the G&alpha;o signaling pathway, dgk-1 and goa-1. We therefore tested mutants for the three G-protein coupled tyramine receptors: SER-2, TYRA-2, and TYRA-3. Whereas lgc-55 mutants are resistant to the paralytic effects of exogenous tyramine on head movements, we found that ser-2 mutants are resistant to the paralytic effects on body movements. Genetic and pharmacological analysis indicates that SER-2 is coupled to the G&alpha;o (GOA-1) pathway, which has been shown to inhibit neurotransmission. We found that SER-2 is expressed in the VD GABAergic motor neurons, indicating that SER-2 might inhibit GABA release onto the ventral body muscles. Omega turns are central to the escape response and may require the asymmetric contraction of ventral and dorsal muscle quadrants. Upon anterior touch ser-2 mutants initiate the escape response normally, but fail to fully contract the ventral side of their body, resulting in a loose omega turn. We further analyzed the role of GABAergic VD and DD motor neurons in locomotion and turning by laser ablation. Animals lacking VD motor neurons moved with a ventral bias and were able to fully contract the ventral musculature during an omega turn, while animals lacking DD motor neurons moved with a dorsal bias and could not relax the dorsal musculature, resulting in a loose omega turn. Our results indicate that the tyraminergic inhibition of GABA release on the ventral side allows the animal to engage in an efficient escape and steer away from the stimulus. This suggests that tyramine plays an essential role in the temporal control of the escape response through the synaptic activation of fast acting ionotropic receptor, LGC-55, and extra synaptic activation of slow acting metabotropic receptor, SER-2.