Biology subjects

Bista, B.

Publications and source records attributed to Bista, B..

4 recordsLinked to original sources

bioRxiv2026

X-Y divergence of house fly (Musca domestica) proto-sex chromosomes follows distinct evolutionary trajectories despite residing in the same genome

Sex determination systems and sex chromosomes frequently differ between species. One cause of these differences is new sex determining genes that drive evolutionary turnover of sex chromosomes. At the earliest stages of this turnover, X and Y (or Z and W) chromosomes start out as nearly identical homologs, and they can diverge via chromosomal rearrangements (e.g., inversions) that suppress X-Y recombination. However, multiple examples from across animals and plants provide exceptions to this canonical model of sex chromosome evolution. For example, some X-Y pairs remain undifferentiated for long evolutionary time periods, while other sex chromosomes become differentiated without chromosomal rearrangements. How or why these non-canonical trajectories occur remains elusive, despite increasing evidence of their pervasiveness. The house fly, Musca domestica, is a well-suited system to address this gap because all six chromosomes can be a Y, providing multiple replicates of a natural experiment within a single genomic environment. To test for canonical and non-canonical evolutionary trajectories, we generated haplotype-resolved chromosome-level assemblies from five strains of the house fly, each of which carries a different Y chromosome (IM, IIM, IIIM, VM, and YM). We identified an inversion on only one of the sex chromosomes (IIM), which was associated with elevated X-Y divergence but did not capture the male-determining locus. In contrast, there was X-Y divergence across almost the entire length of the IM, IIIM, and VM sex chromosomes, despite no detectable inversions. YM was the only sex chromosome to contain substantial Y-specific sequences, which were limited to a segment on one end of the chromosome containing the male-determining gene. This YM chromosome, and its corresponding X, were highly diverged from the X chromosome found in many other flies (Muller element F), despite a strong cytological resemblance. This study highlights how multiple different canonical and non-canonical modes of sex chromosome evolution can co-exist within a single genome.

genomics↗

bioRxiv2023

Characterization of the First Turtle Organoids: A Model for Investigating Unique Adaptations with Biomedical Potential

Painted turtles are remarkable for their well-developed freeze tolerance and associated resilience to hypoxia/anoxia, oxidative stress, and ability to supercool. They are, therefore, an ideal model for biomedical research on hypoxia-induced injuries (including strokes), tissue cooling during extensive surgeries, and organ cryopreservation. Yet, the seasonal reproduction and slow maturation of turtles hinder basic and applied biomedical research. To overcome these limitations, we developed the first adult stem cell-derived turtle hepatic organoids, which provide 3D self-assembled structures that mimic their original tissue and allow for in vitro testing and experimentation without constantly harvesting donor tissue and screening offspring. Our pioneering work with turtles represents the first for this vertebrate Order and complements the only other organoid lines from non-avian reptiles, derived from snake venom glands. Here we report the isolation and characterization of hepatic organoids derived from painted, snapping, and spiny softshell turtles spanning [~]175 million years of evolution, with a subset being preserved in a biobank. Morphological and transcriptomics revealed organoid cells resembling cholangiocytes, which was then compared to the tissue of origin. Deriving turtle organoids from multiple species and life stages demonstrates that our techniques are broadly applicable to chelonians, permitting the development of functional genomic tools currently missing in most herpetological research. When combined with genetic editing, this platform will further support studies of genome-to-phenome mapping, gene function, genome architecture, and adaptive responses to climate change, among others. We discuss the unique abilities of turtles, including their overwintering potential, which has implications for ecological, evolutionary, and biomedical research. SIGNIFICANCEHere we developed the first turtle-derived organoid biobank from the liver of multiple chelonians with a subset characterized via histology, RNA sequencing transcriptomics, single-nuclei RNA sequencing, and transmission electron microscopy. Furthermore, we discuss the potential of the 3D organoid model to investigate unique physiological adaptations of turtles which could unravel the molecular mechanisms underlying their overwintering capacity, opening the door for in vitro biomedical studies relevant to hepatic ischemia-reperfusion injury to organ cryopreservation, beyond fundamental ecology and evolution. This organoid biobank represents a novel resource for the scientific community to support research regarding the unique adaptations of this understudied Order of vertebrates.

genetics↗

bioRxiv2019

Socio-demographic correlates and clustering of Non-Communicable Diseases risk factors among reproductive aged women of Nepal: Results from Nepal Demographic Health Survey 2016

Globally, Non Communicable Diseases (NCDs) are the major killer diseases, majority of which are attributable to common risk factors like smoking, alcohol intake, physical inactivity and low fruits/vegetable consumption. Clustering of these risk factors increases the risk of developing NCDs. The occurrence of NCDs among women is alarmingly high, and this invites impact on upcoming generation too. So, this study aimed to assess the prevalence and clustering of selected risk factors and their socio-demographic determinants in Nepalese women using Nepal Demographic and Health Survey (NDHS) 2016 data.\n\nNDHS applied stratified multi-stage cluster sampling to reach to the individual respondent for representing the whole nation. This study included analysis of data of 6,396 women of age 15 to 49 years. Chi-square test for bivariate analysis and multiple poisson regression to calculate adjusted prevalence ratio was applied.\n\nA total of 8.91% participants were current smoker. Similarly, 22.19% and 11.45% of participants were overweight and hypertensive respectively. Around 6.02% of participants had a co-occurrence of two NCDs risk factors. Smoking, overweight and hypertension were significantly associated with age, education, province, wealth index and ethnicity. Risk factors were more likely to cluster in women aged 40-49 years (APR=2.95, CI: 2.58-3.38), widow/separated (APR=3.09, CI: 2.24-4.28) and Dalit) (APR=1.34, CI: 1.17-1.55).\n\nThis study found that NCD risk factors were disproportionately distributed by age, education, socio-economic status and ethnicity and clustered in more vulnerable groups such as widow/separated, Dalit and Janajati.

epidemiology↗

bioRxiv2019

Factors Associated with Suicidal Ideation and Suicidal Attempts among Adolescent Students in Nepal: Findings from Global School Based Students Health Survey

IntroductionSuicide has been recognized as a public health problem with high burden in low and middle income countries. Suicide has long lasting psychological trauma on friends and relatives in addition to loss of economic productivity. Although the need of high quality evidence is acknowledged for designing suicide prevention program, Nepal lacks evidence from reliable and nationally representative data. In this context, this study aimed to estimate the prevalence of suicidal ideation and attempt and identify the factors associated with them.\n\nMaterials and MethodsTotal of 6,531 students of grade 7 to 11 from 74 schools representing all three ecological belts and five development regions participated in this cross sectional study. To select the representative sample from study population, we used the two stage cluster sampling method. The respondents filled the self-administed standardized questionnaire. We carried out a Complex survey analysis for adjusting the selection probability of each research participants.\n\nResultsNearly 14% had considered suicide while 10.33% had attempted suicide. Factors associated with suicidal ideation were the food insecurity (OR=2.31, CI=1.64-3.27), anxiety (OR=2.53, CI=1.48-4.30), loneliness (OR=2.50, CI=1.41-4.44) and gender (OR=1.38, CI=1.03, 1.88) as risk factors of suicidal ideation and anxiety (OR=2.99, CI=1.18-7.64), loneliness (OR=2.19, CI=1.28-3.74) truancy(OR= 1.99, CI=1.39-2.87), cigarette use(OR=3.06, CI=1.32-7.09) and gender (OR=1.60, CI=1.07-2.39) as risk factors of suicidal attempt. Having 3 or more close friends was found to have protective effect (OR=0.35, CI=0.16-0.74) against suicidal attempt.\n\nConclusionsStudy reveals the relatively high prevalence of suicidal ideation and suicidal attempt among school-going adolescents in Nepal. Appropriate coping strategies for factors like anxiety, loneliness seem could be useful for preventing both suicidal ideation and attempt.

epidemiology↗