Nathalie Pujol et al. (2001) Worm Breeder's Gazette "Ver midi IV"

Jonathan Ewbank, Nathalie Pujol

[Worm Breeder's Gazette, 2001]

La quatrieme reunion annuelle des equipes francaises ayant un interet pour C. elegans se tiendra le Vendredi 23 fevrier 2001 a Luminy, Marseille. Contact: pujol@ibdm.univ-mrs.fr ewbank@ciml.univ-mrs.fr

Felix MA et al. (2002) Hermann, Editeurs des Sciences et des Arts. Paris, France. "Caenorhabditis elegans. Un organisme modele en biologie."

Labouesse M, Segalat L, Felix MA

[Hermann, Editeurs des Sciences et des Arts. Paris, France., 2002]

L'espce Caenorhabditis elegans fut dcrite en 1900 Alger par E. Maupas, qui s'intressait son mode de reproduction hermaphrodite. Plus tard, vers le milieu du vingtime sicle, V. Nigon et ses collaboratuers Lyon tudirent les reorganizations cellulaires accompagnant la fecundation et les premiers clivages. J. Brun isola les preiers mutants morpholgiques.

Goldstein P (1987) Cell Biol Int Rep "Multiple synaptonemal complexes (polycomplexes): origin, structure and function."

Goldstein P

[Cell Biol Int Rep, 1987]

Multiple synaptonemal complexes (polycomplexes) (PC) are similar in structure to synaptonemal complexes (SC) and are also highly conserved through evolution. They have been described in over 70 organisms throughout all life forms. The appearance of PCs are restricted to meiotic and germ-line derived tissues and are most commonly present after SC formation. However, in a number of animals and plants, both extra- and intranuclear PCs are present during premeiotic and pre-pachytene stages. The structure and biochemical composition of PCs is similar to SCs that the basic unit is tripartite, consisting of two lateral elements and a central region (in which transverse elements are located), and the dimensions of such structures are equivalent. Stacking of SC subunits, while still maintaining equivalent SC dimensions, creates a problem since the lateral elements (LE) would then be twice as thick in the PC as compared to the SC. Recently, it has been shown that the LE of the SC is actually multistranded, thus the LE of each subunit of the PC is half as thick as its counterpart in the SC.

Fan PC et al. (1985) Southeast Asian J Trop Med Public Health "Experimental infection of subperiodic Brugia malayi in laboratory rats with emphasis on evaluation by four techniques."

Hsu YP, Huang CM, Wu CC, Ho CM, Fan PC

[Southeast Asian J Trop Med Public Health, 1985]

Infective larvae of subperiodic B. malayi from South Kalimantan (Borneo), Indonesia collected from laboratory-raised Ae. togoi mosquitoes after feeding on infected mongolian gerbils (Meriones unguiculatus) were inoculated subcutaneously into the groin areas of 15 SD and 36 LE rats. Blood was examined weekly by membrane filtration and thick smears starting 10 weeks post-infection. Microfilariae were found in 3 SD and 4 LE rats, the mf infection rate of 20% and 11% respectively. The prepatent period was significantly shorter in the SD rats (99-112 days) than those in the LE rats (110-153 days). The patent period was longer in the LE rats (208-703 days) than in the SD rats (236-543 days), and the mf density was similar (17.5 mf/20 c.mm blood against 16 mf/20 c.mm blood). At necropsy, 6 (3 female and 3 male) adult worms were recovered from 3 of 6 SD rats and 12 (9 female and 3 male) adult worms from 4 of 20 LE rats; all worms were found in the testes. The results of xenodiagnostic, histochemical staining and measuring spicules and protuberances, demonstrated clearly the difference between both species of Brugia. All dissected Ar. subalbatus mosquitoes exposed to B. pahangi became infected (100%), but none of those to subperiodic B. malayi were infected (0%). The mf of both species of Brugia in thick films stained with naphthol-AS-TR-phosphate showed that the excretory and anal pores of subperiodic B. malayi mf exhibited acid phosphatase activity and only a little activity was seen in other parts; while B. pahangi mf showed heavy diffuse acid phosphatase activity along the entire length of the body.(ABSTRACT TRUNCATED AT 250 WORDS)

Frezal, Lise et al. (2015) International Worm Meeting "Caenorhabditis briggsae and its two natural viruses, coevolution in a 'menage a trois'."

BRESARD, Gautier, Felix, Marie-Anne, Frezal, Lise

[International Worm Meeting, 2015]

We study the natural coevolution between Caenorhabditis briggsae and its two recently described RNA viruses called Santeuil and Le Blanc (1, 2). The main advantage of this system is to combine the access to wild host and virus populations with powerful molecular tools and experimental evolution designs. We characterized the incidence of the two C. briggsae viruses in France and found that they are found in sympatry. By monitoring the viral RNAs in wild-caught C. briggsae isolates using Fluorescent In Situ Hybridization, we demonstrated that the Le Blanc and Santeuil viruses could coexist in one host population, one animal and one intestinal cell. Molecular variation of the wild-caught viruses was assessed by sequencing their two RNA molecules. While both viruses' diversities are geographically structured, we detected balancing selection on the RNA-dependent RNA polymerase (RdRp) locus in one local Santeuil population. Despite the frequent incidence of coinfection in the wild, we found no evidence for genetic exchange (recombination or RNA reassortment) between the Santeuil and Le Blanc viruses. However, we found clear evidence for RNA reassortment between different Santeuil virus variants. Finally, we investigated natural variation in C. briggsae resistance to each virus. We tested a set of wild isolates -representative of C. briggsae worldwide diversity- for their sensitivity to the Santeuil and Le Blanc viruses. While temperate C. briggsae genotypes are generally susceptible to both viruses, the tested tropical C. briggsae genotypes are resistant to both viruses. Most interestingly, two Japanese C. briggsae genotypes show specific resistance to the Le Blanc virus. To understand the genetic basis of the general and virus-specific resistances of C. briggsae, we carried out a QTL-mapping approach using recombinant inbred lines between AF16 and HK104 (3) and identified a main QTL region on chromosome IV responsible for the variation in resistance to Santeuil virus infection.(1) Felix, Ashe, Piffaretti et al. 2011 PloS Biology. (2) Franz et al. 2012 Journal of Virology. (3) Ross et al. 2011 PLoS Genetics..

Pfarr KM et al. (2009) Parasite Immunol "Filariasis and lymphoedema."

Pfarr KM, Specht S, Debrah AY, Hoerauf A

[Parasite Immunol, 2009]

Among the causes of lymphoedema (LE), secondary LE due to filariasis is the most prevalent. It affects only a minority of the 120 million people infected with the causative organisms of lymphatic filariasis (LF), Wuchereria bancrofti and Brugia malayi/timori, but is clustered in families, indicating a genetic basis for development of this pathology. The majority of infected individuals develop filarial-specific immunosuppression that starts even before birth in cases where mothers are infected and is characterized by regulatory T-cell responses and high levels of IgG4, thus tolerating high parasite loads and microfilaraemia. In contrast, individuals with this pathology show stronger immune reactions biased towards Th1, Th2 and probably also Th17. Importantly, as for the aberrant lymph vessel development, innate immune responses that are triggered by the filarial antigen ultimately result in the activation of vascular endothelial growth factors (VEGF), thus promoting lymph vessel hyperplasia as a first step to lymphoedema development. Wolbachia endosymbionts are major inducers of these responses in vitro, and their depletion by doxycycline in LF patients reduces plasma VEGF and soluble VEGF-receptor-3 levels to those seen in endemic normals preceding pathology improvement. The search for the immunogenetic basis for LE could lead to the identification of risk factors and thus, to prevention; and has so far led to the identification of single-nucleotide polymorphisms (SNP) with potential functional relevance to VEGF, cytokine and toll-like receptor (TLR) genes. Hydrocele, a pathology with some similarity to LE in which both lymph vessel dilation and lymph extravasation are shared sequelae, has been found to be strongly associated with a VEGF-A SNP known for upregulation of this (lymph-)angiogenesis factor.

Alkan , Cigdem et al. (2017) International Worm Meeting "Interactions between Caenorhabditis nematodes and viruses infecting them naturally."

Ruaud, Albane, Alkan , Cigdem, BRESARD, Gautier, Felix, Marie-Anne

[International Worm Meeting, 2017]

The discovery of RNA viruses that naturally infect C. elegans and C. briggsae serves as an ideal model system to study antiviral immunity and host-pathogen co-evolution. The Orsay virus only infects C. elegans whereas Santeuil and Le Blanc viruses only infect C. briggsae. Intraspecifically, within both species we found a wide variation in viral sensitivity, as well as a positive correlation among wild isolates in sensitivity to both viruses in C. briggsae. An exception to this correlation is the C. briggsae strain HK104, which is specifically resistant to Le Blanc virus but sensitive to Santeuil virus. Taking advantage of this natural variation in the host, we use a genetic approach from the host side and use Recombinant Inbred Lines (RILs) to first map the recombinant genomic regions participating to the resistance/sensitivity in a general and/or specific manner. The RILs were phenotyped for the sensitivity to the relevant viruses using Fluorescent In Situ Hybridization (FISH). The genotype (SNP markers from pool sequencing) and phenotype (resistance/sensitivity from FISH) data were used to perform QTL analysis. Several Near Isogenic Lines (NILs) were created by introgressing the candidate regions. C. briggsae AF16 is resistant to both Santeuil and Le Blanc viruses while C. briggsae HK104 is specifically sensitive to the Santeuil virus. Using AF16xHK104 Advanced Intercrossed RILs (AIRILs) (Ross et al. 2011), two QTLs were detected on chromosomes III and IV for Santeuil virus sensitivity. The NILs in the AF16 background confirm both candidate regions. C. briggsae JU1498 is sensitive to both Santeuil and Le Blanc viruses. Using JU1498xHK104 RILs, a QTL on chromosome II was detected and is being introgressed. Once candidate polymorphisms associated with the virus sensitivity/resistance are identified, we will test them by RNAi knockdown, transformation rescue and/or CRISPR-mediated gene replacement.

BRESARD, Gautier et al. (2013) International Worm Meeting "Specificity of interaction between Caenorhabditis and their natural viruses."

Felix, Marie-Anne, BRESARD, Gautier

[International Worm Meeting, 2013]

Species involved in host-pathogen relationships exert selective pressures on each other. This co-evolution situation results in an arms race between host and pathogen, which may lead to specialisation of their interactions. We recently found three related horizontally-transmitted RNA viruses that naturally infect C. elegans or C. briggsae, called Orsay, Santeuil and Le Blanc viruses (Felix et al. 2011, Franz et al. 2012). Here we study their specificity for C. elegans vs. C. briggsae, and at the intraspecific level in C. briggsae. We first used viral filtrates to infect a set of C. elegans and C. briggsae isolates, and measured by RT-PCR the virus ability to replicate. We find that the Orsay virus can infect C. elegans but not C. briggsae, whereas Santeuil and Le Blanc viruses infect C. briggsae, but not C. elegans. Thus, each virus shows specificity toward one of these two Caenorhabditis species. Given that C. briggsae can be infected by two viruses, we then measured viral replication after infection of C. briggsae isolates by either Santeuil or Le Blanc viruses, using RT-qPCR. We observed 1) wide variation among C. briggsae isolates; 2) correlation between the sensitivities to each virus; 3) an exception to the correlation. Schematically, C. briggsae isolates can be separated into two groups: sensitive isolates, in which the viruses replicate efficiently; and resistant ones, in which the viruses either disappear or are barely maintained. Strikingly, all sensitive strains belong to the temperate C. briggsae clade, raising the possibility that sensitivity is derived within this clade. The exception to the correlation in sensitivity is HK104, a temperate-clade isolate from Japan. HK104 is sensitive to the Santeuil virus, but resistant to Le Blanc. This result opens the possibility to study specificity of host-pathogen interactions through genetic analysis.

Duerr JS et al. (1997) International C. elegans Meeting "COLOCALIZATION OF TWO VESICULAR NEURO-TRANSMITTER TRANSPORTERS IN IDENTIFIED NEURONS"

Erickson JD, Eiden LE, Gaskin J, Rand JB, Frisby DL, Duke A, Duerr JS

[International C. elegans Meeting, 1997]

We have previously shown that unc-17 encodes the C. elegans vesicular acetylcholine transporter (VAChT), and that it is an excellent marker for cholinergic neurons. We have now identified the vesicular monoamine transporter (VMAT) in C. elegans. VMATs are required for the loading of synaptic vesicles with dopamine, serotonin, and other biogenic amine transmitters. When C. elegans VMAT is expressed in mammalian cells, it has serotonin transport activity. The C. elegans VMAT gene appears to be cat-1; cat-1(e1111) animals are deficient for dopamine-mediated behaviors and are totally deficient for VMAT immuno-staining, and these phenotypes can be rescued (at least partially) by a mammalian VMAT transgene. C. elegans VMAT is associated with synaptic vesicles in approximately 25 neurons. These include all of the cells thought to contain dopamine and serotonin, plus a few others. Although, in general, the immuno-reactivity specific for VAChT and VMAT identify different sets of cells, there appear to be a few neurons that express both transporters: these cells contain serotonin, suggesting that they are both cholinergic and serotonergic. These include the 2 HSN cells and VC4 and VC5. The VC cells are of interest because, although all 6 VC neurons have strong expression of VAChT, only VC4 and VC5 appear to express VMAT. The HSN cells are of interest because not only are they known to contain serotonin, but previous genetic and pharmacological studies suggested that they utilize another neurotransmitter (thought to be acetylcholine) in addition to serotonin (Weinshenker et al., 1995). These data are supported and extended by our results: the demonstration of 2 gene products in these mature, fully differentiated neurons, each essential for the release of a neurotransmitter, strongly suggests that these cells use 2 classical neurotransmitters. (Supported by grants from NIGMS and OCAST.)

Frezal, Lise et al. (2013) International Worm Meeting "Microevolution and coexistence of Santeuil and Le Blanc viruses in Caenorhabditis briggsae. ."

Frezal, Lise, Felix, Marie-Anne

[International Worm Meeting, 2013]

We recently found three viruses, Orsay, Santeuil and Le Blanc, which naturally infect Caenorhabditis nematodes (1,2). These ss(+)RNA viruses cause intestinal cell symptoms and are horizontally transmitted. Whereas C. elegans can so far only be infected by the Orsay virus, European C. briggsae genotypes are susceptible to both Santeuil and Le Blanc viruses, and both viruses have been found in the same locations. This vulnerability of C. briggsae to two viruses enables studies of in vivo viral competition and of the mechanisms driving their short-term evolution, as well as the impact of their competition on worm fitness. RNA viruses may evolve rapidly through both high mutation rates and recombination events. The impact of recombination widely varies from one viral species to another but in all cases, for recombination to occur, different virus types have to infect the same host cell. The first step is thus to assess whether different virus species can co-infect the same worm population, the same animal and the same cell. By using quantitative RT-PCR, we demonstrate that the Le Blanc and Santeuil viruses can coexist in a worm population, even when originally introduced at widely different concentrations. The two viruses are jointly maintained over 10 worm generations. We presently investigate the co-infection at the whole organism and single cell levels by tracking the viral RNAs in co-infected worms using Fluorescent In Situ Hybridization. 1- Felix, Ashe, Piffaretti et al. 2011 PloS biology. 2- Franz et al. 2012 Journal of virology.