Interference of paratuberculosis with the diagnosis of tuberculosis in a goat flock with a natural mixed infection

Detection of infected animals is a key step in eradication programs of tuberculosis. Paratuberculosis infection has been demonstrated to compromise the specificity of the diagnostic tests. However, its effect on their sensitivity has not been clarified. In the present study, skin tests and the interferon-gamma (IFN-gamma) assay were evaluated in a goat flock (n=177) with a mixed tuberculosis-paratuberculosis infection in order to assess the possible effect of paratuberculosis on their sensitivity. Culture of mycobacteria was performed as the gold standard to determine the true infection status. All techniques showed lower sensitivities than previously described; the single intradermal tuberculin (SIT) test and the IFN-gamma assay detected 71% (62.4-78.6, 95% C.I.) of the infected animals; the single intradermal cervical comparative tuberculin (SICCT) test detected only 42.7% (34.1-51.7, 95% C.I.) of infected animals. The highest level of sensitivity was obtained when SIT test and IFN-gamma assay were combined in parallel (90.8%, 84.5-95.2, 95% C.I.). Sensitivities of the tests were also assessed by comparing animals suffering tuberculosis and animals with a mixed infection; tests were found to be more effective in the former group. Paratuberculosis seems to have a major effect in the sensitivity of the diagnostic tests under study, and therefore must be taken into account; in particular, the use of the SICCT test should be questioned when both tuberculosis and paratuberculosis are present.     

The concept of effective population size loses its meaning in the context of optimal management of diversity using molecular markers

Effective population size is a key parameter in conservation genetics. In the management of conservation programs using pedigree information, there is a consensus that the optimal method for maximizing effective population size is to calculate the contribution of each potential parent (the number of offspring that each individual leaves to the next generation) by minimizing the global pedigree-based coancestry between potential parents weighted by their contributions. When using molecular data, the optimal method for managing genetic diversity will remain the same but now the molecular coancestry calculated from markers will replace the pedigree-based coancestry. However, in this situation, the concept of effective population size loses its meaning because with optimal molecular management, genetic diversity increases in early generations and therefore effective population size takes negative values. Furthermore, in the long term, the molecular effective population size does not attain an asymptotic value but it shows an unpredictable behaviour.     

Genetic identification of horse mackerel and related species in seafood products by means of forensically informative nucleotide sequencing methodology

In the present study, a methodology based on the amplification of a fragment of mitochondrial cytochrome b and subsequent phylogenetic analysis (FINS: forensically informative nucleotide sequencing) to genetically identify horse mackerels have been developed. This methodology makes possible the identification of more than 20 species belonging to the families Carangidae, Mullidae, and Scombridae. The main novelty of this work lies in the longest number of different horse mackerel species included and in the applicability of the developed methods to all kinds of processed products that can be found by consumers in markets around the world, including those that have undergone intensive processes of transformation, as for instance canned foods. Finally, the methods were applied to 15 commercial samples, all of them canned products. Therefore, these methods are useful for checking the fulfillment of labeling regulations for horse mackerels and horse mackerel products, verifying the correct traceability in commercial trade, and fisheries control.