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The Mongolian gerbil has become a model organism of increasing importance for the understanding of aging, epilepsy, the process of domestication or sociobiological questions. We report the development and characterization of the first nine polymorphic dinucleotide repeat loci in this species. Average observed heterozygosity and allele number of laboratory animals measured 0.136 (SE = +/-0.065) and 1.78 (SE = +/-0.278) compared to 0.761 (SE = +/-0.025) and 9.2 (SE = +/-0.57) found for a reference group of wild gerbils. The extreme low genetic variation observed in laboratory animals is caused by several severe population size bottlenecks due to the initial founder event and the later establishment of subpopulations. Reduced levels of allelic polymorphism in experimental animals hamper genetic mapping or parental studies. Therefore experiments relying on kinship analyses have to be carried out on wild animals. Estimates of genetic identity and parental exclusion were calculated as Pid = 2.8 x 10(-12) and Pex > 0.999 in wild gerbils. Laboratory gerbil strains show the expected high degree of genetic similarity. However, significant allele frequency differences (P < .001) between American and European gerbils at some microsatellite loci may still allow discrimination between breeding lines.

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1. The effect of long-term, moderate heat stress (30 to 32 degrees C) on heat shock protein 70 (Hsp70) concentration in mononuclear blood cells and plasma concentrations of 3,5,3'-triiodothyronine (T3) and corticosterone in laying hens was investigated. 2. Three groups of 48 hens each (Ethopian line [Angete Melata, Na], New Hampshire [NH], F1 cross [Na x NH]) were divided into an experimental group (24 each) and a control group (24 each, ambient temperature 18 to 20 degrees C), respectively. All hens were kept in individual cages up to an age of 68 weeks and performance data were recorded. 3. Blood samples were taken from the wing vein of 12 hens from each group at weeks 22, 38, 51 and 65 (12 hens x 3 lines x 2 treatments). Mononuclear blood cells were isolated and Hsp70 concentrations were determined by Western Blot analysis with a monoclonal anti-Hsp70 antibody. T3 and corticosterone were measured with commercially available ELISA and RIA kits, respectively. 4. The moderate heat stress caused significantly increased Hsp70 levels compared with the control groups in weeks 51 and 65. However, the responses of the lines were not uniform at different ages. 5. In contrast, T3 levels were significantly decreased in stressed birds regardless of line and age. There was no effect of treatment and line on corticosterone levels during the experimental period. 6. Our results indicate that Hsp70 and T3 levels are affected by mild heat stress applied over a long period but are both involved in independent mechanisms of acquisition of thermotolerance. Further investigations are necessary to clarify whether the observed differences in Hsp70 response between the genotypes are indicators for differences in thermotolerance.

We have isolated 14 differentially displayed and 10 further expressed sequence tags (ESTs) from Musculus biceps femoris of newborn healthy and splay leg piglets. By comparison with EMBL/GenBank data we could identify nine porcine homologues to human genes (TATA box binding protein associated factor B TAF1B; B-cell CLL/lymphoma 7B BCL7B; pyruvate dehydrogenase kinase, isoenzyme 4 PDK4; ribosomal protein S10 RPS10; SPARC-like 1 SPARCL1; epithelial protein lost in neoplasm beta EPLIN; N-myc downstream-regulated gene 2 NDRG2; pleiomorphic adenoma gene like 2 PLAGL and, BCL-2 associated transcription factor short form BTFS). Eight fragments correspond to uncharacterized ESTs and 7 ESTs had no significant match with database sequences. These data provide the first expression profiles in skeletal muscle of neonatal piglets and are a basis for candidate gene investigations for congenital splay leg in piglets. Eleven ESTs were physically mapped to porcine chromosomes 1, 3, 4, 5, 7, 8, 9 and 10 and contribute to the comparative map of humans and pigs.