Etude du polymorphisme inter et intraspécifique chez les nématodes parthénogénétiques du genre Meloidogyne. Application à l'analyse comparative de lignées quasi-isogéniques avirulentes et virulentes de Meloidogyne incognita

*INRA Laboratoire de santé végétale et environnement BP 2078 06606 Antibes Cedex (FRA) Diffusion du document : INRA Laboratoire de santé végétale et environnement BP 2078 06606 Antibes Cedex (FRA) Diplôme : Dr. d'Universit

High‐resolution DNA fingerprinting of parthenogenetic root‐knot nematodes using AFLP analysis

International audienceAmplified fragment length polymorphism (AFLP) analysis has been used to characterize 15 root‐knot nematode populations belonging to the three parthenogenetic species Meloidogyne arenaria , M. incognita and M. javanica. Sixteen primer combinations were used to generate AFLP patterns, with a total number of amplified fragments ranging from 872 to 1087, depending on the population tested. Two kinds of polymorphic DNA fragments could be distinguished: bands amplified in a single genotype, and bands polymorphic between genotypes (i.e. amplified in not all but at least two genotypes). Based on presence/absence of amplified bands and pairwise similarity values, all the populations tested were clustered according to their specific status. Significant intraspecific variation was revealed by AFLP, with DNA fragments polymorphic among populations within each of the three species tested. M. arenaria appeared as the most variable species, while M. javanica was the least polymorphic. Within each specific cluster, no general correlation could be found between genomic similarity and geographical origin of the populations. The results reported here showed the ability of the AFLP procedure to generate markers useful for genetic analysis in root‐knot nematodes

Effects of irradiation on Plasmodium falciparum sporozoite hepatic development: implications for the design of pre-erythrocytic malaria vaccines.

Immunization with irradiation-attenuated Plasmodium sporozoites confer protection against live sporozoite challenge. Protection relies primarily on cytotoxic lymphocyte activity against infected hepatocytes, and is suppressed when sporozoites are over-irradiated. Here, we demonstrate that over-irradiated (25-30 krad) Plasmodium falciparum sporozoites invade human hepatocytes and transform into uninucleate liver-trophozoites with the same efficiency as non-irradiated and irradiation-attenuated (12-15 krad) sporozoites. Since hepatocytes infected with over-irradiated non-protective sporozoites are likely to express sporozoite-derived peptide/major histocompatibility complex class I molecules on their surface, our results strongly suggest that sporozoite proteins are not the main immunogens involved in protection, and thus may not per se constitute proper malaria vaccine candidates

Molecular cloning of a cDNA encoding an amphid-secreted putative avirulence protein from the root-knot nematode Meloidogyne incognita

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Virulence and molecular diversity of parthenogenetic root-knot nematodes Meloidogyne spp.

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