Ovine X-chromosome microsatellites at the OarAE25 and OarAE133 loci

Genome-wide cross-amplification of domestic sheep microsatellites in bighorn sheep and mountain goats

We tested for cross-species amplification of microsatellite loci located throughout the domestic sheep (Ovis aries) genome in two north American mountain ungulates (bighorn sheep, Ovis canadensis, and mountain goats, Oreamnos americanus). We identified 247 new polymorphic markers in bighorn sheep (≥ 3 alleles in one of two study populations) and 149 in mountain goats (≥ 2 alleles in a single study population) using 648 and 576 primer pairs, respectively. Our efforts increased the number of available polymorphic microsatellite markers to 327 for bighorn sheep and 180 for mountain goats. The average distance between successive polymorphic bighorn sheep and mountain goat markers inferred from the Australian domestic sheep genome linkage map (mean ± 1 SD) was 11.9 ± 9.2 and 15.8 ± 13.8 centimorgans, respectively. The development of genomic resources in these wildlife species enables future studies of the genetic architecture of trait variation.

Microsatellite variation in Scandinavian Cervidae using primers derived from Bovidae

The possibility of using microsatellite primers developed in Bovidae to amplify microsatellite markers in Cervidae was surveyed by using 75 microsatellite primer sets of bovine, ovine or caprine origin to analyse DNA from moose, red deer, reindeer and roe deer from Scandinavia. On average for the four cervids, approximately 50% of the ovine/caprine primer pairs amplified a specific PCR product, compared to only 16% of the bovine primers. Approximately 50% of both ovine/caprine and bovine primers that amplified a specific product were polymorphic, giving 15 polymorphic microsatellite markers in moose, 11 in red deer, 21 in reindeer and 10 in roe deer. Reindeer had a higher proportion of polymorphic loci, more alleles per locus and higher mean heterozygosity than the other cervids.

In vitro and early in vivo development of sheep gynogenones and putative androgenones

Genomic imprinting, where only one of the two parental genes is expressed, occurs in many phyla. In mammals, however, this phenomenon has been primarily studied in mice, and to a lesser extent, in humans. To understand how genomic imprinting may affect development in other species, particularly those with a different mode of placental development from mice and humans, 339 sheep zygotes were micromanipulated to contain either 2 large (presumptive male) or 2 small (presumptive female) pronuclei. One hundred and twenty-seven of these embryos and 86 manipulated and nonmanipulated control embryos were transferred to recipient ewes over 3 breeding seasons. Twenty-one control and 7 experimental conceptuses were recovered on day 21. Four of these conceptuses derived from zygotes with 2 small pronuclei were identified by karyotyping to be gynogenones (maternal-derived genome). While the gross morphology of the embryos appeared no different to those of normal controls, the extra-embryonic tissue from the conceptuses showed some hypertrophy and hypervascularization. Preliminary Northern blots of mRNA from allantoic and trophoblast tissue showed an overexpression of H19 and an underexpression of IGF2. Although the sheep gynogenetic phenotype contrasts with that seen in mice, these two genes appear to be similarly differentially expressed.