-
[
Med Sci (Paris),
2009]
Cell-cell signaling is essential for the development of multi-cellular organisms. Indeed, membrane traffic is required for the correct sorting and function of receptors and ligands. In the past decades, many genetic screens performed in C. elegans and Drosophila have been crucial to identify the role of intracellular traffic in signaling. In this review, we discuss recent work that led to the identification of Wntless, a sorting receptor for WNT, and of the retromer, a protein complex required for the recycling of Wntless from endosomes to the trans-Golgi network.
-
[
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
-
[
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.
-
[
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.
-
[
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)
-
[
J Parasitol,
1953]
The axenic cultivation (i.e., growth in the absence of other living organisms) of the free-living soil nematode, Rhabditis briggsae, requires a complex medium including one or more heat-labile, protein-like substances which have been termed "factor Rb". It has been shown that factor Rb can be provided by preparations from liver or chick embryo juice or by human plasma or certain of its fractions. Moreover, it has recently been reported in abstract that a dialysed fraction of buffered aqueous liver extract will support excellent growth of R. briggsae when supplemented with known substances only. The present paper reports the results of recent studies on the nature and properties of factor Rb in liver protein and on various supplementations of certain unheated liver preparations as media for R. briggsae. Aqueous, unheated horse liver extract (hereinafter referred to as LE), prepared by centrifuging liver homogenate and taking supernatant, has been treated in various ways to provide information on the properties of factor Rb. Such preparations have been variously supplemented and tested as media for the axenic cultivation of R. briggsae. The principle supplementation used has been the supernatant (ALE) from autoclaved LE. Both partly and completely defined supplementations have also been employed. From these studies some advance has been made in the direction of a completely defined medium for R.
-
[
Nat Commun,
2017]
During cell division, spindle microtubules ensure an equal repartition of chromosomes between the two daughter cells. While the kinetochore-dependent mechanisms that drive mitotic chromosome segregation are well understood, in oocytes of most species atypical spindles assembled in absence of centrosomes entail poorly understood mechanisms of chromosome segregation. In particular, the structure(s) responsible for force generation during meiotic chromosome separation in oocytes is unclear. Using quantitative light microscopy, electron tomography, laser-mediated ablation, and genetic perturbations in the Caenorhabditis elegans oocyte, we studied the mechanism of chromosome segregation in meiosis. We find spindle poles are largely dispensable, and in fact act as brakes for chromosome segregation. Instead, our results suggest that CLS-2-dependent microtubules of the meiotic central spindle, located between the segregating chromosomes and aligned along the axis of segregation, are essential. Our results support a model in which inter-chromosomal microtubules of the central spindle push chromosomes apart during meiotic anaphase in oocytes.
-
[
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..
-
[
Zootaxa,
2022]
Rhagovelia medinae sp. nov., of the hambletoni group (angustipes complex), and R. utria sp. nov., of the hirtipes group (robusta complex), are described, illustrated, and compared with similar congeners. Based on the examination of type specimens, six new synonymies are proposed: R. elegans Uhler, 1894 = R. pediformis Padilla-Gil, 2010, syn. nov.; R. cauca Polhemus, 1997 = R. azulita Padilla-Gil, 2009, syn. nov., R. huila Padilla-Gil, 2009, syn. nov., R. oporapa Padilla-Gil, 2009, syn. nov, R. quilichaensis Padilla-Gil, 2011, syn. nov.; and R. gaigei, Drake Hussey, 1947 = R. victoria Padilla-Gil, 2012 syn. nov. The first record from Colombia is presented for R. trailii (White, 1879), and the distributions of the following species are extended in the country: R. cali Polhemus, 1997, R. castanea Gould, 1931, R. cauca Polhemus, 1997, R. gaigei Drake Hussey, 1957, R. elegans Uhler, 1894, R. femoralis Champion, 1898, R. malkini Polhemus, 1997, R. perija Polhemus, 1997, R. sinuata Gould, 1931, R. venezuelana Polhemus, 1997, R. williamsi Gould, 1931, and R. zeteki Drake, 1953.
-
[
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.