Selection forMeloidogyne incognita virulence against resistance genes from tomato and pepper and specificity of the virulence/resistance determinants

Experiments were designed to analyze the relationships between the root-knot nematodeMeloidogyne incognita and resistant tomato and pepper genotypes. From a natural avirulent isolate, near-isogenic nematode lineages were selected with virulence either against the tomatoMi resistance gene or the pepperMe3 resistance gene. Despite the drastic selection pressure used, nematodes appeared unable to overcome the pepperMe1 gene, therefore suggesting some differences in the resistance conferred byMe1 andMe3 in this species. Nematodes virulent onMi-resistant tomatoes were not able to reproduce onMe1-resistant nor onMe3-resistant peppers, and nematodes virulent onMe3-resistant peppers were not able to reproduce onMi-resistant tomatoes nor onMe1-resistant peppers. These results clearly demonstrate the specificity ofM. incognita virulence against resistance genes from both tomato and pepper, and indirectly suggest that gene-for-gene relationships could occur between these two solanaceous crops and the nematode.     

Animal species identification in food products: evolution of biomolecular methods

Species identification in food has increasingly acquired importance due to public health, economic and legal concerns. Traditional methods have relied on the identification of morphological traits, but this does not lead to accurate identification of those species used in many types of processed food. As a result, laboratory techniques have been devised using electrophoretic and immunological methods focussing on protein profiles and, more recently, biomolecular techniques have been developed. However, these techniques also present problems and difficulties, especially in the case of matrices that are heterogeneous or have been subjected to severe treatments during processing.     

La reproduction et la notion d'espece chez le genre Meloidogyne

La présente étude met en relief la difficulté de définir des unités taxino-miques claires et valables chez les Meloidogyne. Dans ce contexte, les études caryo-logiques devraient apporter une meilleure précision. Le mode de reproduction par parthénogenése contribue à isoler de multiples clones aux comportements encore mal connus. Il existe de ce fait certains risques d'enrichissement de la faune locale par des populations étrangéres, même lorsqu'il s'agit d'une espéce déjà présente dans le biotope considéré. Les mécanismes de la reproduction et leurs altérations méritent une grande attention en raison des répercussions qu'ils peuvent provoquer sur les autres facultés biologiques de ces nématodes.     

Biomolecular Approaches for the Identification of Tuna Species

Veterinary Research Communications -     

Polymorphisme génétique chez Heterodera avenae1

On a étudié par l'électrophorèse la variabilityé de certains enzymes avec l'idée de trouver des caractéres plus commodes pour la distinction des pathotypes. Les premiers resultats font apparaître qu' Heterodera avenae , contrairement à ce qui a été observé chez le genre voisin Meloidogyne , est très polymorphe pour les quatre premiers enzymes déjà analyses, soit: deux estérases, la malate déhydrogénase (MDH) et les phosphatases acides. Les differences d'une population à l'autre semblent pour l'instant plutôt se situer au niveau du nombre d'allèles presents et de leurs fréquences respectives dans chacune d'elles. Différents phénomènes biologiques ont été parallèlement mis en évidence comme l'≪ inbreeding ≫à faible densité de population ou la fécondation effective d'une femelle par plusieurs mâles.     

Contribution of human alpha-defensin 1, 2, and 3 to the anti-HIV-1 activity of CD8 antiviral factor

It has been known since 1986 that CD8 T lymphocytes from certain HIV-1-infected individuals who are immunologically stable secrete a soluble factor, termed CAF, that suppresses HIV-1 replication. However, the identity of CAF remained elusive despite an extensive search. By means of a protein-chip technology, we identified a cluster of proteins that were secreted when CD8 T cells from long-term nonprogressors with HIV-1 infection were stimulated. These proteins were identified as alpha-defensin 1, 2, and 3 on the basis of specific antibody recognition and amino acid sequencing. CAF activity was eliminated or neutralized by an antibody specific for human alpha-defensins. Synthetic and purified preparations of alpha-defensins also inhibited the replication of HIV-1 isolates in vitro. Taken together, our results indicate that alpha-defensin 1, 2, and 3 collectively account for much of the anti-HIV-1 activity of CAF that is not attributable to beta-chemokines.