Use of Random Amplified Polymorphic DNA (RAPD) for generating specific DNA probes for Oxyuroid species (Nematoda)

Random amplified DNA markers (RAPD ; Williams et al., 1990) were used to obtained specific RAPD fragments characterising different species of oxyuroids. We tested six species of worms parasitizing vertebrates or invertebrates: Passalurus ambiguus Rudolphi, 1819, parasite of Leporids ; Syphacia obvelata (Rudolphi, 1802) Seurat, 1916, a parasite of rodents; Blatticola blattae (Graeffe, 1860) Chilwood, 1932 parasite of the cockroach Blattella germanica ; Hammerschmidtiella diesingi (Hammerschmidt, 1838) Chitwood, 1932 and Thelastoma bulhoesi (Magalhaes, 1990) Travassos, 1929, parasites of the cockroach Periplaneta americana, and an undescribed parasite species of a passalid insect from New Caledonia. Among 15 oligonucleotides tested, nine produced several specific bands allowing the interspecific discrimination

Utilisation des RAPD (Random Amplified Polymorphic DNA) pour générer des marqueurs spécifiques d'especes d'oxyures (Nematoda)

WOS:000072659600006International audienceRandom amplified DNA markers (RAPD ; Williams et al., 1990) were used to obtained specific RAPD fragments characterising different species of oxyuroids. We tested six species of worms parasitizing vertebrates or invertebrates: Passalurus ambiguus Rudolphi, 1819, parasite of Leporids ; Syphacia obvelata (Rudolphi, 1802) Seurat, 1916, a parasite of rodents; Blatticola blattae (Graeffe, 1860) Chilwood, 1932 parasite of the cockroach Blattella germanica ; Hammerschmidtiella diesingi (Hammerschmidt, 1838) Chitwood, 1932 and Thelastoma bulhoesi (Magalhaes, 1990) Travassos, 1929, parasites of the cockroach Periplaneta americana, and an undescribed parasite species of a passalid insect from New Caledonia. Among 15 oligonucleotides tested, nine produced several specific bands allowing the interspecific discrimination.La technique du RAPD (Random Amplified Polymorphic DNA; William et al., 1990) a été utilisée pour caractériser différentes espèces d'oxyures. Nous avons testé six espèces d'oxyures de vertébrés ou d'invertébrés : Passalurus ambiguus Rudolphi, 1819, un parasite de léporidés ; Syphacia obvelata (Rudolphi, 1802) Seurat, 1916, un parasite de rongeurs ; Blatticola blattae (Graeffe, 1860) Chitwood, 1932, parasite de la blatte Blattella germanica (L.) ; Hammerschmidtiella diesingi (Hammerschmidt, 1838) Chitwood, 1932, et Thelastoma bulhoesi (Magalhaes, 1990} Travassos, 1929, parasites de la blatte Periplaneta americana, et une espèce non décrite d'un passalide de Nouvelle-Calédonie. Sur les 15 amorces testées, neuf ont produit plusieurs bandes spécifiques permettant la différenciation interspécifique

Characterization of a ribonuclease III-like protein required for cleavage of the pre-rRNA in the 3′ETS in Arabidopsis

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Comparative genetic diversity of parasites and their hosts: population structure of an urban cockroach and its haplo-diploid parasite (oxyuroid nematode)

WOS:000086284800010International audienceFew studies have investigated the genetic structure of both host and parasite populations at a level of populations and at a level of individuals. We investigated the genetic structure of the urban cockroach Blattella germanica and its oxyuroid parasite Blatticola blattae. Random amplified polymorphic DNA (RAPD) markers were used to quantify genetic diversity between and within four populations (from two cities in France) of the host and its parasite. Diversity based on phenotypic frequencies was calculated for each RAPD marker using Shannon-Wiener's index. We used multivariate analyses to test the significance of genetic differentiation between host and parasite populations. Analysis of molecular variance was also used. Both methods gave similar results. Diversity between pairs of individuals was estimated by Nei & Li's index. Genetic diversity was higher within host or parasite populations (80% and 82%, respectively, of explained diversity) than between host or parasite populations (20% and 18%, respectively, explained diversity). The genetic distances between pairs of parasite populations (or individuals) were not correlated with the genetic distances between the corresponding pairs of host populations (or individuals)

Characterization of a ribonuclease III-like protein required for cleavage of the pre-rRNA in the 3 ' ETS in Arabidopsis

Ribonuclease III (RNaseIII) is responsible for processing and maturation of RNA precursors into functional rRNA, mRNA and other small RNA. In contrast to bacterial and yeast cells, higher eukaryotes contain at least three classes of RNaseIII, including class IV or dicer-like proteins. Here, we describe the functional characterization of AtRTL2, an Arabidopsis thaliana RNaseIII-like protein that belongs to a small family of genes distinct from the dicer family. We demonstrate that AtRTL2 is required for 3external transcribed spacer (ETS) cleavage of the pre-rRNA in vivo. AtRTL2 localizes in the nucleus and cytoplasm, a nuclear export signal (NES) in the N-terminal sequence probably controlling AtRTL2 cellular localization. The modeled 3D structure of the RNaseIII domain of AtRTL2 is similar to the bacterial RNaseIII domain, suggesting a comparable catalytic mechanism. However, unlike bacterial RNaseIII, the AtRTL2 protein forms a highly salt-resistant homodimer that is only disrupted on treatment with DTT. These data indicate that AtRTL2 may use a dimeric mechanism to cleave double-stranded RNA, but unlike bacterial or yeast RNase III proteins, AtRTL2 forms homodimers through formation of disulfide bonds, suggesting that redox conditions may operate to regulate the activity of RNaseIII

Upon heat stress processing of ribosomal RNA precursors into mature rRNAs is compromised after cleavage at primary P site in Arabidopsis thaliana

International audienceTranscription and processing of 45S rRNAs in the nucleolus are keystones of ribosome biogenesis. While these processes are severely impacted by stress conditions in multiple species, primarily upon heat exposure, we lack information about the molecular mechanisms allowing sessile organisms without a temperature-control system, like plants, to cope with such circumstances. We show that heat stress disturbs nucleolar structure, inhibits pre-rRNA processing and provokes imbalanced ribosome profiles in Arabidopsis thaliana plants. Notably, the accuracy of transcription initiation and cleavage at the primary P site in the 5'ETS (5' External Transcribed Spacer) are not affected but the levels of primary 45S and 35S transcripts are, respectively, increased and reduced. In contrast, precursors of 18S, 5.8S and 25S RNAs are rapidly undetectable upon heat stress. Remarkably, nucleolar structure, pre-rRNAs from major ITS1 processing pathway and ribosome profiles are restored after returning to optimal conditions, shedding light on the extreme plasticity of nucleolar functions in plant cells. Further genetic and molecular analysis to identify molecular clues implicated in these nucleolar responses indicate that cleavage rate at P site and nucleolin protein expression can act as a checkpoint control towards a productive pre-rRNA processing pathway

Population dynamics of host-parasite interactions in a cockroach-oxyuroid system

WOS:000173729000008International audienceHost-parasite interactions of an urban cockroach, Blattella germanica, and its oxyuroid parasite, Blatticola blattae, were investigated. Life history data of host and parasites were collected under laboratory conditions. These data were used to model the effect of the parasite on the population dynamics of the host in order to understand the parasite's impact on the host population. The aggregation of parasites within a host was under-dispersed. Hosts normally mere found to be infected with only one male and one female and rarely two or three. However, the primary sex ratio after hatching was 1.1 (males/females). Female parasite longevity equalled the life span of its host. B. blattae had a significant impact on the survival rate of the cockroach larvae and their time to reach maturity, but no effect on the survival rate of the adults. Infected host females produced fewer first oothecae than uninfected ones. Using the population parameters a simple model was developed to estimate the parasite's effect on the population dynamics of its host. According to the model the parasite suppresses the cockroach populations by ca 11%. Hence, the effect of the parasite does not appear strong enough to be used as a biological control agent by itself