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Infectious pancreatic necrosis (IPN) is a well-known acute viral disease of salmonid species. We have identified quantitative trait loci (QTLs) associated with resistance to this disease in rainbow trout. We searched for linkage among 51 microsatellite markers used to construct a framework linkage map in backcross families of rainbow trout (Oncorhynchus mykiss), produced by crossing IPN-resistant (YN-RT201) and -susceptible (YK-RT101) strains. Two putative QTLs affecting disease resistance were detected on chromosomes A (IPN R S-1) and C (IPN R/S-2), respectively, suggesting that this is a polygenic trait in rainbow trout. These markers have great potential for use in marker-assisted selection (MAS) for IPN resistance and provide the basis for cloning of IPN resistance genes. Clarification of the genetic bases of complex traits has broad implications for fundamental research, but will also be of practical benefit to fish breeding.

Previous studies using methods varying from traditional serologic tests to molecular biology techniques have shown that in northeastern Brazil, Entamoeba dispar was more prevalent than E. histolytica. In this study, the prevalence was established by using E. histolytica stool antigen detection kits and a polymerase chain reaction (PCR) with genomic DNA extracted from cultured trophozoites in all four-nuclei, amoeba-positive samples from a population living in Macaparana in northeastern Brazil. Among 1,437 stool samples analyzed, only 59 (4.1%) were positive for four nuclei amoeba. However, all of these samples were negative in an immunoenzymatic assay for the presence of E. histolytica-specific galactose adhesin. Of 59 cultivated samples, only 31 showed trophozoites. Extraction of DNA from these 31 samples, followed by the PCR, showed that 23 samples (74.19%) were positive for E. dispar and no amplification was observed for pathogenic E. histolytica. The remaining eight samples were negative for both species. These findings are consistent with those previously reported.

This article documents the addition of 153 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Brassica oleracea, Brycon amazonicus, Dimorphandra wilsonii, Eupallasella percnurus, Helleborus foetidus, Ipomoea purpurea, Phrynops geoffroanus, Prochilodus argenteus, Pyura sp., Sylvia atricapilla, Teratosphaeria suttonii, Trialeurodes vaporariorum and Trypanosoma brucei. These loci were cross‐tested on the following species: Dimorphandra coccicinea, Dimorphandra cuprea, Dimorphandra gardneriana, Dimorphandra jorgei, Dimorphandra macrostachya, Dimorphandra mollis, Dimorphandra parviflora and Dimorphandra pennigera.

Fusarium solani fungus (teleomorph Haematonectria haematococca) is of relevance for agriculture, producing a disease that causes significant losses for many cultivars. Moreover, F. solani is an opportunistic pathogen to animals and humans. The complexity associated to its correct identification by traditional methods justifies the efforts of using molecular markers for isolates characterization. In this work, three PCR-based methods (one PCR-ribotyping and two PCR-fingerprinting) were used to investigate the molecular variability of eighteen F. solani isolates from four Brazilian States, collected from different substrates. Genetic analysis revealed the intraspecific variability within the F. solani isolates, without any correlation to their geographical origin and substrate. Its polymorphism was observed even in the very conserved sequence of rDNA locus, and the SPAR marker (GTG)5 showed the highest polymorphism. Together, those results may contribute to understand the relation between fungal genetic variability and cultivars resistance phenotypes to fungal-caused diseases, helping plant-breeding programs.

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