Spondylitic changes in long-finned pilot whales (Globicephala melas) stranded on Cape Cod, Massachusetts, USA, between 1982 and 2000.

The primary bone pathology diagnoses recognized in cetacea are osteomyelitis and spondylosis deformans. In this study, we determined the prevalence, type, and severity of vertebral pathology in 52 pilot whales, a mass stranding species that stranded on Cape Cod, Massachusetts, between 1982 and 2000. Eleven whales (21%) had hyperostosis and ossification of tendon insertion points on and between vertebrae, chevron bones, and costovertebral joints, with multiple fused blocks of vertebrae. These lesions are typical of a group of interrelated diseases described in humans as spondyloarthropathies, specifically ankylosing spondylitis, which has not been fully described in cetacea. In severe cases, ankylosing spondylitis in humans can inhibit mobility. If the lesions described here negatively affect the overall health of the whale, these lesions may be a contributing factor in stranding of this highly sociable species.

Preimplantation embryo development (Ped) gene copy number varies from 0 to 85 in a population of wild mice identified as Mus musculus domesticus.

The preimplantation embryo development (Ped) gene regulates the rate of preimplantation embryonic cleavage division and subsequent embryo survival. In the mouse, the Ped gene product is Qa-2 protein, a nonclassical MHC class I molecule encoded by four tandem genes, Q6/Q7/Q8/Q9. Most inbred strains of mice have all four genes on each allelic chromosome, making a total of eight Qa-2 encoding genes, but there are a few strains that are missing all eight genes, defining a null allele. Mouse strains with the presence of the Qa-2 encoding genes express Qa-2 protein and produce embryos with a faster rate of preimplantation embryonic development and a greater chance of embryo survival compared to mouse strains with the null allele. There is extensive evidence that the human homolog of Qa-2 is HLA-G. HLA-G in humans, like Qa-2 in mice, is associated with enhanced reproductive success. The human population is an outbred population. Therefore, for a better comparison to the human population, we undertook an investigation of the presence of the genes encoding Qa-2 in an outbred population of mice. We used Real-Time Quantitative PCR to quantify the number of Qa-2 encoding genes in a population of 32 wild mice identified as Mus musculus domesticus both by morphologic assessment and by PCR analysis of their DNA. We found great variability in the number of Qa-2 encoding genes in the wild mice tested. The wild mouse with the highest number of Qa-2 encoding genes had 85 such genes, whereas we discovered one wild mouse without any Qa-2 encoding genes. Evolutionary implications of a range of Qa-2 encoding gene numbers in the wild mouse population are discussed, as well as the relevance of our findings to humans.

Ped gene deletion polymorphism frequency in wild mice.

The Ped gene influences the rate of cleavage of preimplantation embryos and their subsequent survival. Embryos that express the product of the Ped gene, Qa-2 protein, cleave at a faster rate than embryos with an absence of Qa-2 protein. In addition, the Ped gene has pleiotropic effects on reproduction. Thus, there is a reproductive advantage to those mouse strains that are Qa-2 positive. The presence or absence of Qa-2 is reflected at the DNA level by the presence or absence (deletion polymorphism) of the gene(s) encoding Qa-2 protein. Many inbred and wild-derived mouse strains have been characterized as Qa-2 positive or negative, but no previous studies have looked at the distribution of the Ped gene in a population of free-living wild mice. The purpose of this study was to determine the Ped gene deletion polymorphism frequency in a sample of free-living wild mice. Twenty-nine mice were collected and identified as Mus musculus. Genomic DNA extraction was performed on tail tips, and PCR was used to amplify a region from the Ped gene. Known Qa-2 positive and negative mice were used as controls. Results showed that all 29 wild mice were positive for the Ped gene. Since the Ped gene is dominant and provides a reproductive advantage, it is not surprising that all of the wild mice were Qa-2 positive. However, our assay could not distinguish homozygous from heterozygous mice. It is possible that the Qa-2 deletion polymorphism is segregating in the population, and a larger sample size would identify some Qa-2 negative mice.