Current Status of Sex Sorted Semen and its Long Term effect on Population Dynamics and Y-Chromosome Degeneration of the Breed Among Dairy Animals in Jharkhand, India: A Review

Sex Sorted Semen gives the liberty of producing offspring of the desired sex - in farming animals by using it in conjunction with other assisted reproductive technologies such as Artificial Insemination and In-Vitro Fertilization after selecting the healthy sperm and separating into X-Female and Y-male Chromosome bearing populations based on their DNA content. It is an important biotechnological tool to increase the milk production and the profitability of Dairy Industry. Current study deals with the Principle, methods, main method, advantages, disadvantages and the current status of Sex sorted semen in India and Jharkhand. The main emphasis of this study is to draw the attention of Scientific fraternity towards the effect of Sex Sorted Semen on Population dynamics. The Sex Sorted semen increases the deviation of ratio between Male and Female Population from ideal 1:1, thereby decreasing the effective population size Ne and thus slowly reducing the viability and survivability of the population or breed concerned. Further the already depleting Y chromosomes will be reaped off all its genes in long run at a faster rate due to antagonistic selection pressure arising out of Artificial selection via Sex Sorted Semen acting against all the gene of Y chromosome of the breed or population concerned which might disturb many vital genes and the associated functions. The degeneration and extinction of scientists have been predicted long ago. The effect of Sex Sorted semen on Y- chromosome degeneration is yet to be pointed out, calculated and subsequently verified in any of the literatures. SSS is indeed a boon for India as well as Jharkhand. It might be too early to predict about the negative impact of SSS on population dynamics and Y-Chromosome degeneration. Further research work must be done to assess the extent and authencity of above mentioned impact( Predicted theoretically) by calculation as well as practical field based Experimentation.

Y recombination arrest and degeneration in the absence of sexual dimorphism

Current theory proposes degenerated sex chromosomes evolve via three successive steps: recombination arrest, which links male-beneficial alleles to the Y chromosome; degeneration of these regions due to the inefficacy of natural selection in the absence of recombination; and lastly, the evolution of dosage compensation to correct the resulting low expression of X-linked genes in males. Here we investigate new models of sex chromosome evolution incorporating the coevolution of cis- and trans-regulators of gene expression. We show that the early emergence of dosage compensation favors the maintenance of Y-linked inversions by creating sex-antagonistic regulatory effects. This is followed by inversion degeneration caused by regulatory divergence between the X and Y chromosomes. In stark contrast to the current theory, the whole process occurs without any selective pressure related to sexual dimorphism.

Enriched G-quadruplexes on the Drosophila Male X Chromosome Function as Insulators of Dosage Compensation Complex

The evolution of sex chromosomes has resulted in half X chromosome dosage in males as females. Dosage compensation, or the two-fold upregulation in males, was thus evolved to balance the gene expression between sexes. However, the step-wise evolutionary trajectory of dosage compensation during Y chromosome degeneration is still unclear. Here, we show that the specific structured elements G-quadruplexes (G4s) are enriched on the X chromosome in Drosophila melanogaster. Meanwhile, on the X chromosome, the G4s are underrepresented on the H4K16 acetylated regions and the binding sites of dosage compensation complex male-specific lethal (MSL) complex. Peaks of G4 density and potential are observed at the flanking regions of MSL binding sites, suggesting G4s act as insulators to precisely up-regulate certain regions in males. Thus, G4s may be involved in the evolution of dosage compensation process through fine-tuning one-dose proto-X chromosome regions around MSL binding sites during the gradual Y chromosome degeneration.One Sentence SummaryG-quadruplexes act as insulators to precisely up-regulate X chromosome in males.

Temporal Orders and Y Chromosome Futures: Of Mice, Monkeys, and Men

We bring together conceptual readings of time and temporality to discuss evolutionary theories of Y chromosome degeneration as they are spoken about in scientific and popular forums. In doing so, we suggest that debates over Y chromosome degeneration involve a form of abduction – tacking back and forth between different pasts, presents, futures – that frames templates for producing and securing sexed and gendered presents. Here we are using ‘sexed’ as a way of talking about physical bodies and ‘gendered’ as social ways of constructing those sexed bodies. We suggest that arguments over Y chromosome degeneration are as important for current debates surrounding sex, gender, science, molecular biology and a “crisis of masculinity” as they are for (ascertaining) the future of human evolution.

The Size and Content of the Sex-Determining Region of the Y Chromosome in Dioecious Mercurialis annua, a Plant with Homomorphic Sex Chromosomes

Many dioecious plants have sex chromosomes that are cytologically heteromorphic, but about half of species lack cytological differences between males and females and are thus homomorphic. Very little is known about the size and content of the non-recombining sex-determining region (SDR) in these species. Here, we assess the size and content of the SDR of the diploid dioecious herb Mercurialis annua, which has homomorphic sex chromosomes and shows signatures of mild Y-chromosome degeneration. We used RNAseq to identify new Y-linked markers for M. annua. Twelve of 24 transcripts with male-specific and male-biased expression could only be PCR-amplified from males and are thus Y-linked. We found a further six Y-linked sequences that were present in males but not females using genome capture data from multiple populations. We used the Y-linked sequences to identify and sequence 17 sex-linked bacterial artificial chromosomes (BACs), which form 11 groups of non-overlapping sequence, covering a total sequence length of about 1.5 Mb. Content analysis of this region suggests it is enriched for repeats, has a low gene density and contains few candidate sex-determining genes. The BACs map to a subset of the sex-linked region of the genetic map, which is estimated to be at least 14.5 Mb. This is substantially larger than estimates for other dioecious plants with homomorphic sex chromosomes, especially given the small genome size of M. annua. Our data provide a rare, high-resolution view of the homomorphic Y chromosome of a dioecious plant.