Biology subjects

Moran, B.

Publications and source records attributed to Moran, B..

4 recordsLinked to original sources

bioRxiv2021

Predictability and parallelism in the contemporary evolution of hybrid genomes

Hybridization between species is widespread across the tree of life. As a result, many species, including our own, harbor regions of their genome derived from hybridization. Despite the recognition that this process is widespread, we understand little about how the genome stabilizes following hybridization, and whether the mechanisms driving this stabilization tend to be shared across species. Here, we dissect the drivers of variation in local ancestry across the genome in replicated hybridization events between two species pairs of swordtail fish: Xiphophorus birchmanni x X. cortezi and X. birchmanni x X. malinche. We find unexpectedly high levels of repeatability in local ancestry across the two types of hybrid populations. This repeatability is attributable in part to the fact that the recombination landscape and locations of functionally important elements play a major role in driving variation in local ancestry in both types of hybrid populations. Beyond these broad scale patterns, we identify dozens of regions of the genome where minor parent ancestry is unusually low or high across species pairs. Analysis of these regions points to shared sites under selection across species pairs, and in some cases, shared mechanisms of selection. We show that one such region is a previously unknown hybrid incompatibility that is shared across X. birchmanni x X. cortezi and X. birchmanni x X. malinche hybrid populations.

evolutionary biology↗

bioRxiv2020

Two new hybrid zones expand the swordtail hybridization model system

Natural hybridization events provide unique windows into the barriers that keep species apart as well as the consequences of their breakdown. Here we characterize hybrid populations formed between the northern swordtail fish Xiphophorus cortezi and X. birchmanni from collection sites on two rivers. We develop sensitive and accurate local ancestry calling for this system based on low coverage whole genome sequencing. Strikingly, we find that hybrid populations on both rivers consist of two genetically distinct subpopulations: a cluster of nearly pure X. birchmanni individuals and one of phenotypically intermediate hybrids that derive ~85-90% of their genome from X. cortezi. Simulations and empirical data suggest that at both sites initial hybridization occurred ~150 generations ago, with little evidence for contemporary gene flow between subpopulations, likely due to strong assortative mating. The patterns of population structure uncovered here mirror those seen in hybridization between X. birchmanni and its sister species, X. malinche. Future comparisons will provide a window into the repeatability of the outcomes of hybridization not only across independent hybridization events between the same species but also across distinct species pairs.

evolutionary biology↗

bioRxiv2020

Optimisation and comparison of orthogonal methods for separation and characterisation of extracellular vesicles to investigate how representative infant milk formula is of milk

This study aimed to separate and characterise extracellular vesicles (EV) from infant milk formula (IMF) and skim milk (SM), to determine how representative the EV content of IMF is to SM. Contaminant casein micelles, due to their abundance and overlapping size, were removed followed by either differential ultracentrifugation (DUC) or gradient ultracentrifugation (GUC). Characterisation included BCA, SDS-PAGE, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), immunoblotting, and imaging flow cytometry (IFCM). NTA reported significantly reduced concentrations of EVs/particles in IMF versus SM; TEM showed intact SM-derived EVs to sparse and disrupted EV-like structures in IMF. Compared to IMF, noticeably stronger bands for EV biomarkers were observed by immunoblotting in SM, indicating compromised EV proteins in IMF; also supported by IFCM. Altogether, we established that EVs are substantially compromised during IMF processing. Furthermore, an optimised method combining acid pre-treatment and GUC for EV separation from milk products has been established.

molecular biology↗

bioRxiv2017

Comparison and Characterisation of Mutation Calling from Whole Exome and RNA Sequencing Data for Liver and Muscle Tissue in Lactating Holstein Cows Divergent for Fertility

Whole exome sequencing has had low uptake in livestock species, despite allowing accurate analysis of single nucleotide variant (SNV) mutations. Transcriptomic data in the form of RNA sequencing has been generated for many livestock species and also represents a source of mutational information. However, there is little information on the accuracy of using this data for the identification of SNVs. We generated a bovine exome capture design and used it to sequence and call mutations from a lactating dairy cow model genetically divergent for fertility (Fert+, n=8; Fert-, n=8). We compared mutations called from liver and muscle transcriptomes from the same animals. Our exome capture demonstrated 99.1% coverage of the exome design of 56.7MB, whereas transcriptomes covered 55 and 46.5% of the exome, or 24.4 and 20.7MB, in liver and muscle respectively after filtering. We found that specificity of SNVs in the transcriptome data is approximately 75% following basic hard-filtering, and could be increased to above 80% by increasing the minimum threshold of reads covering SNVs, but this effect was negated in more highly covered SNVs. RNA-DNA differences, SNVs found in transcriptome but not exome, were discovered and shown to have significantly increased levels of transition mutations in both tissues. Functional annotation of non-synonymous SNVs specific to the high and low fertility phenotypes identified immune response-related genes, supporting previous work that has identified differential expression in the same genes. Publically available RNAseq data may be analysed in a similar way to further increase the utility of this resource.\n\nSummaryThe exome and transcriptome both relate to the same protein-coding regions of the genome. There has been sparse research on characterising mutations in RNA and DNA within the same individuals. Here we characterise the similarities in our Holstein dairy cow animal model. We offer practical and biological results indicating that RNA sequencing is a useful proxy of exome sequencing, itself shown to be applicable to this livestock species using a previously untested commercial application. This potentially unlocks public RNA sequencing data for further analysis, also indicating that RNA-DNA differences may associate with transcriptomic divergence.

genomics↗