Gwilym S. Jones

The domain model for eukaryotic DNA organization 2: A molecular basis for constraints on development and evolution

A model for eukaryotic DNA organization has been proposed in which DNA regulatory processes depend on multiple site-specific DNA-nuclear matrix interactions throughout a DNA domain. In this model gene regulation depends on combinations of a few control factors in a cell to activate cell type-specific genes. This model suggests simple molecular mechanisms for organismal development which can account for sequential activation of appropriate groups of genes throughout development and for specific constraints on developmental pathways. Additionally, these suggested developmental pathways are consistent with mechanisms of evolution in which gradualism and punctuated equilibrium are not exclusive of one another and are interrelated mechanisms of evolution that are both induced by specific chromosomal mutations.

Ectoparasites from beavers from Massachusetts and Maine

Abstract Seven species of beaver mites, Schizocarpus paramingaudi Fain & Whitaker, indianensis Fain et al, postannulatus Fain & Whitaker, virgulatus Fain et al, subvirgulatus Fain et al, inversus Fain et al and spinifer Fain et al were found on three beavers from Massachusetts. Twelve were found on five beavers from Maine, S. mingaudi Trouessart, paramingaudi, alaskensis Fain & Whitaker, reductus Fain & Whitaker, indianensis, tetrapilis Fain et al, postannulatus, distinctus Fain & Whitaker, subvirgulatus, inversus, posticus Fain & Whitaker, protinus Fain & Whitaker, and spinifer. Beaver mites are normally restricted to specific parts of the beaver, and 93.3% of 1162 male adult mites identified were found on the expected part of the beaver as hypothesized. The beaver mite communities from Maine and Alaska, and also from Maine and Indiana were the most similar of four compared, whereas those from Massachusetts and Maine were the least similar. This departure from the expected may have been due to transplant...

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.

DYNAMICS OF TERRITORIAL BEHAVIOR BY COMMON NIGHTHAWKS

Abstract We describe the aggressive defense of a territory by a male Common Nighthawk against a migrating flock of conspecifics in Boston, Massachusetts. This observation is compared with those of Rust (1947) to illustrate the dynamics of territorial behavior in the Common Nighthawk.