A Candidate Subspecies Discrimination System Involving a Vomeronasal Receptor Gene with Different Alleles Fixed in M. m. domesticus and M. m. musculus

Assortative mating, a potentially efficient prezygotic reproductive barrier, may prevent loss of genetic potential by avoiding the production of unfit hybrids (i.e., because of hybrid infertility or hybrid breakdown) that occur at regions of secondary contact between incipient species. In the case of the mouse hybrid zone, where two subspecies of Mus musculus (M. m. domesticus and M. m. musculus) meet and exchange genes to a limited extent, assortative mating requires a means of subspecies recognition. We based the work reported here on the hypothesis that, if there is a pheromone sufficiently diverged between M. m. domesticus and M. m. musculus to mediate subspecies recognition, then that process must also require a specific receptor(s), also sufficiently diverged between the subspecies, to receive the signal and elicit an assortative mating response. We studied the mouse V1R genes, which encode a large family of receptors in the vomeronasal organ (VNO), by screening Perlegen SNP data and identified one, Vmn1r67, with 24 fixed SNP differences most of which (15/24) are nonsynonymous nucleotide substitutions between M. m. domesticus and M. m. musculus. We observed substantial linkage disequilibrium (LD) between Vmn1r67 and Abpa27, a mouse salivary androgen-binding protein gene that encodes a proteinaceous pheromone (ABP) capable of mediating assortative mating, perhaps in conjunction with its bound small lipophilic ligand. The LD we observed is likely a case of association rather than residual physical linkage from a very recent selective sweep, because an intervening gene, Vmn1r71, shows significant intra(sub)specific polymorphism but no inter(sub)specific divergence in its nucleotide sequence. We discuss alternative explanations of these observations, for example that Abpa27 and Vmn1r67 are coevolving as signal and receptor to reinforce subspecies hybridization barriers or that the unusually divergent Vmn1r67 allele was not a product of fast positive selection, but was derived from an introgressed allele, possibly from Mus spretus

Identification of ejaculated proteins in the house mouse (Mus domesticus) via isotopic labeling

<p>Abstract</p> <p>Background</p> <p>Seminal fluid plays an important role in successful fertilization, but knowledge of the full suite of proteins transferred from males to females during copulation is incomplete. The list of ejaculated proteins remains particularly scant in one of the best-studied mammalian systems, the house mouse (<it>Mus domesticus</it>), where artificial ejaculation techniques have proven inadequate. Here we investigate an alternative method for identifying ejaculated proteins, by isotopically labeling females with ¹⁵N and then mating them to unlabeled, vasectomized males. Proteins were then isolated from mated females and identified using mass spectrometry. In addition to gaining insights into possible functions and fates of ejaculated proteins, our study serves as proof of concept that isotopic labeling is a powerful means to study reproductive proteins.</p> <p>Results</p> <p>We identified 69 male-derived proteins from the female reproductive tract following copulation. More than a third of all spectra detected mapped to just seven genes known to be structurally important in the formation of the copulatory plug, a hard coagulum that forms shortly after mating. Seminal fluid is significantly enriched for proteins that function in protection from oxidative stress and endopeptidase inhibition. Females, on the other hand, produce endopeptidases in response to mating. The 69 ejaculated proteins evolve significantly more rapidly than other proteins that we previously identified directly from dissection of the male reproductive tract.</p> <p>Conclusion</p> <p>Our study attempts to comprehensively identify the proteins transferred from males to females during mating, expanding the application of isotopic labeling to mammalian reproductive genomics. This technique opens the way to the targeted monitoring of the fate of ejaculated proteins as they incubate in the female reproductive tract.</p

Preventive palliation in the elderly - Organizing health camps for the rural aged

Most of the needs of elders for support and assistance in the later stages of life are fulfilled by informal helpers. The position of a large number of older persons has become vulnerable due to which it cannot be taken for granted that their children will be able to look after them when they need care in old age, specially in view of the longer life span implying an extended period of dependency and higher costs to meet health and other needs. The condition of the rural elderly is even more pitiable, contrary to our beliefs, as availability, affordability and accessibility to medicare facilities are poor. We undertook the task of organizing a health camp in a rural set-up with the idea of implementing our concept of "preventive palliation" in which excellent palliative care was coupled with a pinch of prevention, like routine checks of blood pressure, routine physical check-ups, etc, so that any aberration can be detected early and necessary rectification measures can be implemented. These periods of routine check-ups can also be used to assess the psycho-social, cultural and emotional problems, if any. Such an approach, say every monthly, gives the elderly something to look forward to and ensures a high degree of customer satisfaction and greatly reduces the burden on the current health system. The challenges faced and the data obtained from this study were shocking. The elderly living in rural areas of the tribal state of Jharkhand suffer from poor physical and mental health, a factor which was rather unexpected in the Indian cultural system in the rural setting. Simple strategies like implementing routine health check ups with provision of "nutritious meal program" can go a long way in mitigating these problems in a cost-effective and simple manner. To make the government-based programs accessible and available to the end-users, participation of local bodies like NGOs is mandatory. Preventive palliation, a concept introduced by Kosish, is the way forward for providing palliative care to the rural-based elderly in most parts of India. This concept takes into account the local cultural, social, financial and long term feasibility and sustainability aspects of the care process

Growth rate and heterozygosity in the plaice, Pleuronectes platessa

Samples of young plaice were examined to see if there was any relationship between growth rate and individual heterozygosity, screened across five polymorphic enzyme loci (Pgm-1, Ada, Mdh-2, Pgi-2, Gpdh-l). Two out of 46 samples showed a significant negative correlation between growth rate and multi-locus heterozygosity; none showed a significant positive correlation. There was no overall tendency to negative or positive correlations. The largest sample (N=689) showed no relationship between multi-locus heterozygosity and growth rate, although one of the five loci, Gpdh-1, showed a significant positive correlation. The only significant correlation in the next largest sample (N= 248) was between multi-locus heterozygosity and growth rate, and that was negative. Fish of intermediate growth rate were not significantly different in heterozygosity from faster or slower growing fish. There was no relationship between variability in growth rate and multi-locus heterozygosity. These findings are discussed in the context of similar surveys from other species, and the conclusion drawn that the universality of a positive relationship between growth rate and multi-locus heterozygosity remains to be established