Genetic diversity in 10 populations of domestic Turkeys by using microsatellites markers.

The domestic turkey is a native breed in danger of extinction due to the introduction of new breeds specializing in meat production and yield. Turkeys have lost some prominence in urban areas, and only certain breeds of turkeys are preserved in rural areas. Wild and domestic turkeys are different; rural or indigenous turkeys, with black plumage, were domesticated from Mexican turkeys and have been reproduced throughout Latin America. Some of them were taken to Europe in the 16th century and later arrived in North America, where they crossed with another wild species, from which the bronze turkey emerged: the ancestor of all commercial turkeys. The objective of the present work was to evaluate the genetic diversity in 10 populations of domestic turkeys worldwide by using breeds from Europe: Spain and Italy; America: Mexico, United States and Brazil; and the Near East: Iran and Egypt. A total of 522 blood samples of both sexes were collected from domestic turkey populations. Thirty-four microsatellites were used to obtain genetic parameters, and genetic diversity was evaluated. All microsatellites used were polymorphic, and a total of 427 alleles were detected across the 34 markers investigated. In this study, a mean number of 13.44 alleles was found. The four most diverse breeds were from the Andalusia, Mexico, United States, and wild populations, which had the highest mean heterozygosity expected (0.619, 0.612, 0.650, and 0.773) and heterozygosity observed (0.422, 0.521, 0.429, and 0.627), respectively. The MNT348 marker deviated from the HWE in all populations. Our study has shown that the populations close to the species origin are more diverse than those resulting from posterior expansions. Mexican birds were the most diverse, followed by the Spanish populations because Spain imported a large number of turkeys coming from America. Such information can be complementary to other genotypic data required to validate the evolutionary relationships among turkey populations.

Vitrification induces critical subcellular damages in ram spermatozoa.

The aim of the present study was to analyse morphological variations in ovine spermatozoa subjected to different cryopreservation protocols using high resolution imaging techniques. Ejaculates were pooled and diluted in Tris-based extender. Aliquots containing 300 × 106 spz/ml were prepared and evaluated a) after the semen collection and pooling, b) after conventional freezing, c) after vitrification of samples maintained at room temperature (22 °C) prior to vitrification, and d) after vitrification of samples maintained at 5 °C prior to vitrification. Sperm motility, acrosome integrity, DNA fragmentation and morphology were assessed. Subcellular sperm changes were assessed and described by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The maintenance of spermatozoa at 5 °C prior to vitrification and the use of 0.4 M sucrose pointed out lower dimensions of area, length and width than fresh, frozen and sperm maintained at 22 °C prior to vitrification. It was observed that the head width and length are significantly higher (P < 0.0001) in fresh spermatozoa than in the vitrified sperm samples. It could be hypothesized that greater intracellular fluid loss during vitrification could prevent damages in the spermatozoon throughout the reduced ice crystals formation, but mainly by the reduction of extracellular ice crystals due to the physical properties modification obtained when high concentrations of sugars are added. This is the first ultramicroscopic study carried out in ovine vitrified spermatozoa, which confirms the functional sperm alterations previously detected.

The Southwestern fringe of Europe as an important reservoir of caprine biodiversity.

BACKGROUND: Portugal and Spain, with six and 22 officially recognized caprine breeds, encompass 25 % of the European Union goat census. Many of these populations have suffered strong demographic declines because of competition with exotic breeds and the phasing-out of low income rural activities. In this study, we have investigated the consequences of these and other demographic processes on the genetic diversity, population structure and inbreeding levels of Iberian and Atlantic goats. METHODS: A sample of 975 individuals representing 25 officially recognized breeds from Portugal and Spain, two small populations not officially recognized (Formentera and Ajuí goats) and two ecotypes of the Tinerfeña and Blanca Celtibérica breeds were genotyped with a panel of 20 microsatellite markers. A wide array of population genetics methods was applied to make inferences about the genetic relationships and demography of these caprine populations. RESULTS: Genetic differentiation among Portuguese and Spanish breeds was weak but significant (FST = 0.07; P < 0.001), which is probably the consequence of their short splitting times and extensive gene flow due to transhumance. In contrast, Canarian goats were strongly differentiated because of prolonged geographic isolation. Most populations displayed considerable levels of diversity (mean He = 0.65). CONCLUSIONS: High diversity levels and weak population structures are distinctive features of Portuguese and Spanish breeds. In general, these local breeds have a reduced census, but are still important reservoirs of genetic diversity. These findings reinforce the need for the implementation of management and breeding programs based on genetic data in order to minimize inbreeding, maintain overall genetic and allelic diversities and breed identities, while at the same time taking into account the within-breed genetic structure.

Genetic structure, relationships and admixture with wild relatives in native pig breeds from Iberia and its islands.

BACKGROUND: Native pig breeds in the Iberian Peninsula are broadly classified as belonging to either the Celtic or the Mediterranean breed groups, but there are other local populations that do not fit into any of these groups. Most of the native pig breeds in Iberia are in danger of extinction, and the assessment of their genetic diversity and population structure, relationships and possible admixture between breeds, and the appraisal of conservation alternatives are crucial to adopt appropriate management strategies. METHODS: A panel of 24 microsatellite markers was used to genotype 844 animals representing the 17 most important native swine breeds and wild populations existing in Portugal and Spain and various statistical tools were applied to analyze the results. RESULTS: Genetic diversity was high in the breeds studied, with an overall mean of 13.6 alleles per locus and an average expected heterozygosity of 0.80. Signs of genetic bottlenecks were observed in breeds with a small census size, and population substructure was present in some of the breeds with larger census sizes. Variability among breeds accounted for about 20% of the total genetic diversity, and was explained mostly by differences among the Celtic, Mediterranean and Basque breed groups, rather than by differences between domestic and wild pigs. Breeds clustered closely according to group, and proximity was detected between wild pigs and the Mediterranean cluster of breeds. Most breeds had their own structure and identity, with very little evidence of admixture, except for the Retinto and Entrepelado varieties of the Mediterranean group, which are very similar. Genetic influence of the identified breed clusters extends beyond the specific geographical areas across borders throughout the Iberian Peninsula, with a very sharp transition from one breed group to another. Analysis of conservation priorities confirms that the ranking of a breed for conservation depends on the emphasis placed on its contribution to the between- and within-breed components of genetic diversity. CONCLUSIONS: Native pig breeds in Iberia reveal high levels of genetic diversity, a solid breed structure and a clear organization in well-defined clusters.

Genetic footprints of Iberian cattle in America 500 years after the arrival of Columbus.

BACKGROUND: American Creole cattle presumably descend from animals imported from the Iberian Peninsula during the period of colonization and settlement, through different migration routes, and may have also suffered the influence of cattle directly imported from Africa. The introduction of European cattle, which began in the 18th century, and later of Zebu from India, has threatened the survival of Creole populations, some of which have nearly disappeared or were admixed with exotic breeds. Assessment of the genetic status of Creole cattle is essential for the establishment of conservation programs of these historical resources. METHODOLOGY/PRINCIPAL FINDINGS: We sampled 27 Creole populations, 39 Iberian, 9 European and 6 Zebu breeds. We used microsatellite markers to assess the origins of Creole cattle, and to investigate the influence of different breeds on their genetic make-up. The major ancestral contributions are from breeds of southern Spain and Portugal, in agreement with the historical ports of departure of ships sailing towards the Western Hemisphere. This Iberian contribution to Creoles may also include some African influence, given the influential role that African cattle have had in the development of Iberian breeds, but the possibility of a direct influence on Creoles of African cattle imported to America can not be discarded. In addition to the Iberian influence, the admixture with other European breeds was minor. The Creoles from tropical areas, especially those from the Caribbean, show clear signs of admixture with Zebu. CONCLUSIONS/SIGNIFICANCE: Nearly five centuries since cattle were first brought to the Americas, Creoles still show a strong and predominant signature of their Iberian ancestors. Creole breeds differ widely from each other, both in genetic structure and influences from other breeds. Efforts are needed to avoid their extinction or further genetic erosion, which would compromise centuries of selective adaptation to a wide range of environmental conditions.

Estimation of the genetic admixture composition of Iberian dry-cured ham samples using DNA multilocus genotypes.

Under current Spanish regulations, the pigs that provide the raw material for the preparation of the country's most appreciated meat-derived product, dry-cured Iberian ham, must be of a specific genetic composition. Only the Duroc breed is accepted for crossing with Iberian pigs, and a maximum of 50% of the Duroc genome is permitted in the animals used to make this ham. This paper describes a set of statistical procedures for detecting the 'breed composition' of Iberian ham via the use of multilocus genotypes obtained by the amplification of 25 microsatellite markers. The proposed procedure detected up to 20% of ham samples with a genetic composition incompatible with present legislation - either because the Duroc genome was present in a percentage greater than that permitted, or because of the significant presence (>25%) of white coat pig genomes. The probability of finding an illegal cured ham was greater in restaurants than in retail grocery stores, and in medium-low category restaurants or stores than in higher category establishments.