Evaluation of 16 loci to examine the cross-species utility of single nucleotide polymorphism arrays.

Large collections of single nucleotide polymorphisms (SNPs) have recently been identified from a number of livestock genomes. This raises the possibility that SNP arrays might be useful for analysis in related species for which few genetic markers are currently available. To address the likely success of such an approach, the aim of this study was to examine the threshold number and position of flanking mutations which act to prevent genotype calls being produced. Sequence diversity was measured across 16 loci containing SNPs known either to work successfully between species or fail between species. In pairwise comparisons between domestic and wild sheep, sequence divergence surrounding working SNP assays was significantly lower than that surrounding non-functional assays. In addition, the location of flanking mismatches tended to be closer to the target SNP in loci that failed to generate genotype calls across species. The magnitude of sequence divergence observed for both working and non-functional assays was compared with the divergence separating domestic sheep from European Mouflon, African Barbary, goat and cattle. The results suggest that the utility of SNP arrays for analysis of shared polymorphism will be restricted to closely related pairs of species. Analysis across more divergent species will, however, be successful for other objectives, such as the identification of the ancestral state of SNPs.

Identifying native animals in crossbred populations: the case of the Sardinian goat population.

The aim of this work was to develop a strategy for using a genetic analysis for identifying native animals in regions where local breeds have been crossed with improved breeds and then compare that strategy to the overall morphology and breeding histories of the herds for identifying these animals. The experiment included the Sardinian goat population, which is a crossbred of native animals with the Maltese breed. Whole herds were assigned to Maltese (five herds; 49 animals), crossbred (18 herds; 117 animals) or Sardinian (12 herds; 164 animals) groups. For the genetic analysis, genotypes of 22 microsatellites were determined on 330 animals, and basic measurements of genetic diversity were calculated. Genetic variability in the microsatellites was different in the three groups. High positive F(IS) showed that inbreeding existed in the subpopulations. The index of genetic differentiation, Nei's standard genetic distance and Reynolds' genetic distance were calculated and found to be significantly different between the three groups. The Sardinian and Maltese groups were the most distant whereas the crossbred group was closer to the Sardinian group. The proportion of the genome derived from two ancestral populations (native Sardinian and Maltese) was assessed using the structure software. Animals were assigned to three clusters on the basis of native Sardinian thresholds. A good correspondence between the empirical (morphology and breeding histories) and the objective genetic analysis was found. Both approaches indicate the presence of three different subpopulations in the Sardinian goat population.

Employment of terbinafine against Pneumocystis carinii infection in rat models.

The anti-Pneumocystis carinii response of terbinafine together with that of three other compounds, trimethoprim sulphamethoxazole (TMP-SMX), atovaquone (ATQ) and albendazole (ALB), has been investigated in immunosuppressed Sprague-Dawley rats with established pneumocystosis. Drugs were administered orally (terbinafine in dosages of 40 and 80 mg/kg per day, TMP 12.5 mg/kg per day plus SMX 62.5 mg/kg per day, ATQ 100 mg/kg per day and ALB 600 mg/kg per day) to six rat groups except one which served as a control. P. carinii pneumonia (PCP) was identified post-mortem in nine (90%) of the control rats which exhibited a marked P. carinii burden, and mean lung weights were higher with respect to the other treatment groups. During treatment, five rats in the control group died, whereas between 11 and 13 rats in all treatment groups survived. In the terbinafine groups (40 mg and 80 mg/kg per day), a mild P. carinii infection developed in three and two rats (27.2 and 18%), respectively, and almost the same infectivity score was obtained for those treated with 40 mg and 80 mg/kg per day. Histological changes in the lungs in animals receiving terbinafine treatment were minimal. Among the remaining compounds the rate of infection was seven (58.3%) for the ALB treatment group and five (45.4%) for the ATQ group (mean score 19.4 +/- 7.1 and 23 +/- 2.1, respectively). In the TMP-SMX treatment group, there were 13 surviving rats and P. carinii organisms were found in two (15.3%, mean infection score 8 +/- 1.1).