Determination of sex of the dry skull using Interstyloid distance and its Medicolegal implications in Tamil Nadu population

Determination of sex using Skeletal remains is a challenging topic with so many tools being used for the sex determination of Skull in this study. The interstyloid process distance were studied in 64 Skulls and were tabulated and analysed. There is a significant difference between the distance in Female skull and Male skull, the former being lesser compared to the later. Further study in this regard may help using Interstyloid process distance as a important tool in identification of the Sex of the Skull.

A Forensic Autopsy Study of Dead Foetuses and Newborns

Background: The term abandonment refers to babies or foetuses which are found abandoned at various unwanted places such as gutter, rubbish dumps, railway tracts and bushes. It does not refer to live born babies left in places, such as hospitals where care can be given by someone other than the mother. Aims and Objectives: To find out the distribution of death cases of newborns/feotuses and to trace its probable reason and its relationship with female foeticide.Methods:A retrospective study of all the medico-legal autopsies of foetuses and newborns was conducted in Forensic medicine and Toxicology department, Government Medical College, Amritsar (Punjab) from Jan 1, 2014 to Jul 31, 2021. During this period, 46 cases of fetal and newborn deaths had been studied.Results:The dead bodies of known foetuses/newborns is 43.5% cases while total unknown cases were 56.5% cases. 32.6% cases were non viable foetuses while 10.8% cases died as a result of prematurity. All the unknown cases (56.5%) were found from the abandoned places like street, bushes, canal side, water bodies that mainly includes pond and railway tract.Conclusion:Despite, the problem is present in every corner of the nation, there is dearth of research studies on this issue. Stringent measures and strict checks are required against antenatal sex determination. The motive behind the abandonment of foetuses can be any, but this grave issue needs urgent attention.

An ancient truncated duplication of the anti-Mullerian hormone receptor type 2 gene is a potential conserved master sex determinant in the Pangasiidae catfish family

The evolution of sex determination (SD) mechanisms in teleost fishes is amazingly dynamic, as reflected by the variety of different master sex-determining genes identified, even sometimes among closely related species. Pangasiids are a group of economically important catfishes in many South-Asian countries, but little is known about their sex determination system. Here, we generated novel genomic resources for 12 Pangasiid species and provided a first characterization of their SD system. Based on an Oxford Nanopore long-read chromosome-scale high quality genome assembly of the striped catfish Pangasianodon hypophthalmus, we identified a duplication of the anti-Mullerian hormone receptor type II gene (amhr2), which was further characterized as being sex-linked in males and expressed only in testicular samples. These first results point to a male-specific duplication on the Y chromosome (amhr2by) of the autosomal amhr2a. Sequence annotation revealed that the P. hypophthalmus Amhr2by is truncated in its N-terminal domain, lacking the cysteine-rich extracellular part of the receptor that is crucial for ligand binding, suggesting a potential route for its neofunctionalization. Short-read genome sequencing and reference-guided assembly of 11 additional Pangasiid species, along with sex-linkage studies, revealed that this truncated amhr2by duplication is also conserved as a male-specific gene in many Pangasiids. Reconstructions of the amhr2 phylogeny suggested that amhr2by arose from an ancient duplication / insertion event at the root of the Siluroidei radiation that is dated around 100 million years ago. Altogether these results bring multiple lines of evidence supporting that amhr2by is an ancient and conserved master sex-determining gene in Pangasiid catfishes, a finding that highlights the recurrent usage of the transforming growth factor β pathway in teleost sex determination and brings another empirical case towards the understanding of the dynamics or stability of sex determination systems.

Transposon-induced epigenetic silencing in the X chromosome as a novel form of dmrt1 expression regulation during sex determination in the fighting fish

Background Fishes are the one of the most diverse groups of animals with respect to their modes of sex determination, providing unique models for uncovering the evolutionary and molecular mechanisms underlying sex determination and reversal. Here, we have investigated how sex is determined in a species of both commercial and ecological importance, the Siamese fighting fish Betta splendens. Results We conducted association mapping on four commercial and two wild populations of B. splendens. In three of the four commercial populations, the master sex determining (MSD) locus was found to be located in a region of ~ 80 kb on LG2 which harbours five protein coding genes, including dmrt1, a gene involved in male sex determination in different animal taxa. In these fish, dmrt1 shows a male-biased gonadal expression from undifferentiated stages to adult organs and the knockout of this gene resulted in ovarian development in XY genotypes. Genome sequencing of XX and YY genotypes identified a transposon, drbx1, inserted into the fourth intron of the X-linked dmrt1 allele. Methylation assays revealed that epigenetic changes induced by drbx1 spread out to the promoter region of dmrt1. In addition, drbx1 being inserted between two closely linked cis-regulatory elements reduced their enhancer activities. Thus, epigenetic changes, induced by drbx1, contribute to the reduced expression of the X-linked dmrt1 allele, leading to female development. This represents a previously undescribed solution in animals relying on dmrt1 function for sex determination. Differentiation between the X and Y chromosomes is limited to a small region of ~ 200 kb surrounding the MSD gene. Recombination suppression spread slightly out of the SD locus. However, this mechanism was not found in the fourth commercial stock we studied, or in the two wild populations analysed, suggesting that it originated recently during domestication. Conclusions Taken together, our data provide novel insights into the role of epigenetic regulation of dmrt1 in sex determination and turnover of SD systems and suggest that fighting fish are a suitable model to study the initial stages of sex chromosome evolution.

Discovery of Sex-Determining Genes in Portunus trituberculatus: A Comparison of Male and Female Transcriptomes During Early Developmental Stages

Portunus trituberculatus is one of the main mariculture crabs of high economic value. To identify genes involved in sex determination, we first performed sex-specific transcriptome sequencing at six larval development stages using a DNA/RNA co-extraction method. A total of 907,952,938 and 828,774,880 reads were obtained from female and male crabs, respectively. 2,379 differentially expressed genes (DEGs) were found between females and males, and were mainly enriched in DNA replication, folate biosynthesis, and retinol metabolism pathways. Furthermore, transcription patterns of genes in the sex-determining region (SD) were analyzed based on the transcriptome data, and one Dmrt gene (PtDMY) was found to be exclusively expressed in males during early developmental stages. Notably, some known sex-related genes, including IAG, Dmrt11E, DmrtB1, and DmrtC2 were significantly down-regulated after knocking down PtDMY. Our results suggested that PtDMY is involved in sex determination and may be one of the key upstream regulators of the sex determination pathway. In addition, the massive volume of transcriptome data obtained in this study provided an important basis for the systematic study of sex determination mechanisms in P. trituberculatus.