During early mammalian embryo development, different epigenetic marks undergo reprogramming and play crucial roles in the mediation of gene expression. Currently, several databases provide multi-omics information on early embryos. However, how interconnected epigenetic markers function together to coordinate the expression of the genetic code in a spatiotemporal manner remains difficult to analyze, markedly limiting scientific and clinical research. Here, we present dbEmbryo, an integrated and interactive multi-omics database for human and mouse early embryos. dbEmbryo integrates data on gene expression, DNA methylation, histone modifications, chromatin accessibility, and higher-order chromatin structure profiles for human and mouse early embryos. It incorporates customized analysis tools, such as "multi-omics visualization," "Gene&Peak annotation," "ZGA gene cluster," "cis-regulation," "synergistic regulation," "promoter signal enrichment," and "3D genome." Users can retrieve gene expression and epigenetic profile patterns to analyze synergistic changes across different early embryo developmental stages. We showed the uniqueness of dbEmbryo among extant databases containing data on early embryo development and provided an overview. Using dbEmbryo, we obtained a phase-separated model of transcriptional control during early embryo development. dbEmbryo offers web-based analytical tools and a comprehensive resource for biologists and clinicians to decipher molecular regulatory mechanisms of human and mouse early embryo development.

A cattle pangenome representation was created based on the genome sequences of 898 cattle representing 57 breeds. The pangenome identified 83 Mb of sequence not found in the cattle reference genome, representing 3.1% novel sequence compared with the 2.71-Gb reference. A catalog of structural variants developed from this cattle population identified 3.3 million deletions, 0.12 million inversions, and 0.18 million duplications. Estimates of breed ancestry and hybridization between cattle breeds using insertion/deletions as markers were similar to those produced by single nucleotide polymorphism-based analysis. Hundreds of deletions were observed to have stratification based on subspecies and breed. For example, an insertion of a Bov-tA1 repeat element was identified in the first intron of the APPL2 gene and correlated with cattle breed geographic distribution. This insertion falls within a segment overlapping predicted enhancer and promoter regions of the gene, and could affect important traits such as immune response, olfactory functions, cell proliferation, and glucose metabolism in muscle. The results indicate that pangenomes are a valuable resource for studying diversity and evolutionary history, and help to delineate how domestication, trait-based breeding, and adaptive introgression have shaped the cattle genome.

Teleost fishes are ancient tetraploids descended from an ancestral whole-genome duplication that may have contributed to the impressive diversification of this clade. Whole-genome duplications can occur via self-doubling (autopolyploidy) or via hybridization between different species (allopolyploidy). The mode of tetraploidization conditions evolutionary processes by which duplicated genomes return to diploid meiotic pairing, and subsequent genetic divergence of duplicated genes (cytological and genetic rediploidization). How teleosts became tetraploid remains unresolved, leaving a fundamental gap in the interpretation of their functional evolution. As a result of the whole-genome duplication, identifying orthologous and paralogous genomic regions across teleosts is challenging, hindering genome-wide investigations into their polyploid history. Here, we combine tailored gene phylogeny methodology together with a state-of-the-art ancestral karyotype reconstruction to establish the first high-resolution comparative atlas of paleopolyploid regions across 74 teleost genomes. We then leverage this atlas to investigate how rediploidization occurred in teleosts at the genome-wide level. We uncover that some duplicated regions maintained tetraploidy for more than 60 million years, with three chromosome pairs diverging genetically only after the separation of major teleost families. This evidence suggests that the teleost ancestor was an autopolyploid. Further, we find evidence for biased gene retention along several duplicated chromosomes, contradicting current paradigms that asymmetrical evolution is specific to allopolyploids. Altogether, our results offer novel insights into genome evolutionary dynamics following ancient polyploidizations in vertebrates.

Gene retrocopies arise from the reverse transcription and insertion into the genome of processed mRNA transcripts. Although many retrocopies have acquired mutations that render them functionally inactive, most mammals retain active LINE-1 sequences capable of producing new retrocopies. New retrocopies, referred to as retro copy number variants (retroCNVs), may not be identified by standard variant calling techniques in high-throughput sequencing data. Although multiple functional FGF4 retroCNVs have been associated with skeletal dysplasias in dogs, the full landscape of canid retroCNVs has not been characterized. Here, retroCNV discovery was performed on a whole-genome sequencing data set of 293 canids from 76 breeds. We identified retroCNV parent genes via the presence of mRNA-specific 30-mers, and then identified retroCNV insertion sites through discordant read analysis. In total, we resolved insertion sites for 1911 retroCNVs from 1179 parent genes, 1236 of which appeared identical to their parent genes. Dogs had on average 54.1 total retroCNVs and 1.4 private retroCNVs. We found evidence of expression in testes for 12% (14/113) of the retroCNVs identified in six Golden Retrievers, including four chimeric transcripts, and 97 retroCNVs also had significantly elevated F ST across dog breeds, possibly indicating selection. We applied our approach to a subset of human genomes and detected an average of 4.2 retroCNVs per sample, highlighting a 13-fold relative increase of retroCNV frequency in dogs. Particularly in canids, retroCNVs are a largely unexplored source of genetic variation that can contribute to genome plasticity and that should be considered when investigating traits and diseases.

In eukaryotes, capped RNAs include long transcripts such as messenger RNAs and long noncoding RNAs, as well as shorter transcripts such as spliceosomal RNAs, small nucleolar RNAs, and enhancer RNAs. Long capped transcripts can be profiled using cap analysis gene expression (CAGE) sequencing and other methods. Here, we describe a sequencing library preparation protocol for short capped RNAs, apply it to a differentiation time course of the human cell line THP-1, and systematically compare the landscape of short capped RNAs to that of long capped RNAs. Transcription initiation peaks associated with genes in the sense direction have a strong preference to produce either long or short capped RNAs, with one out of six peaks detected in the short capped RNA libraries only. Gene-associated short capped RNAs have highly specific 3' ends, typically overlapping splice sites. Enhancers also preferentially generate either short or long capped RNAs, with 10% of enhancers observed in the short capped RNA libraries only. Enhancers producing either short or long capped RNAs show enrichment for GWAS-associated disease SNPs. We conclude that deep sequencing of short capped RNAs reveals new families of noncoding RNAs and elucidates the diversity of transcripts generated at known and novel promoters and enhancers.

Competing endogenous RNAs (ceRNAs) are vital regulators of gene networks in mammals. The involvement of noncoding RNAs (ncRNAs) as ceRNA in genotypic sex determination (GSD) and environmental sex determination (ESD) in fish is unknown. The Chinese tongue sole, which has both GSD and ESD mechanisms, was used to map the dynamic expression pattern of ncRNAs and mRNA in gonads during sex determination and differentiation. Transcript expression patterns shift during the sex differentiation phase, and ceRNA modulation occurs through crosstalk of differentially expressed long ncRNAs (lncRNAs), circular RNAs (circRNAs), microRNAs (miRNAs), and sex-related genes in fish. Of note was the significant up-regulation of a circRNA from the sex-determining gene dmrt1 (circular RNA dmrt1) and a lncRNA, called AMSDT (which stands for associated with male sex differentiation of tongue sole) in Chinese tongue sole testis. These two ncRNAs both share the same miRNA response elements with gsdf, which has an up-regulated expression when they bind to miRNA cse-miR-196 and concurrent down-regulated female sex-related genes to facilitate testis differentiation. This is the first demonstration in fish that ceRNA crosstalk mediated by ncRNAs modulates sexual development and unveils a novel regulatory mechanism for sex determination and differentiation.

Cattle are an important livestock species, and mapping the genomic architecture of agriculturally relevant traits such as disease susceptibility is a major challenge in the bovine research community. Lineage-specific transposable elements (TEs) are increasingly recognized to contribute to gene regulatory evolution and variation, but this possibility has been largely unexplored in ruminant genomes. We conducted epigenomic profiling of the type II interferon (IFN) response in bovine cells and found thousands of ruminant-specific TEs including MER41_BT and Bov-A2 elements predicted to act as IFN-inducible enhancer elements. CRISPR knockout experiments in bovine cells established that critical immune factors including IFNAR2 and IL2RB are transcriptionally regulated by TE-derived enhancers. Finally, population genomic analysis of 38 individuals revealed that a subset of polymorphic TE insertions may function as enhancers in modern cattle. Our study reveals that lineage-specific TEs have shaped the evolution of ruminant IFN responses and potentially continue to contribute to immune gene regulatory differences across modern breeds and individuals. Together with previous work in human cells, our findings demonstrate that lineage-specific TEs have been independently co-opted to regulate IFN-inducible gene expression in multiple species, supporting TE co-option as a recurrent mechanism driving the evolution of IFN-inducible transcriptional networks.

The preconceptual, intrauterine, and early life environments can have a profound and long-lasting impact on the developmental trajectories and health outcomes of the offspring. Given the relatively low success rates of assisted reproductive technologies (ART; ∼25%), additives and adjuvants, such as glucocorticoids, are used to improve the success rate. Considering the dynamic developmental events that occur during this window, these exposures may alter blastocyst formation at a molecular level, and as such, affect not only the viability of the embryo and the ability of the blastocyst to implant, but also the developmental trajectory of the first three cell lineages, ultimately influencing the physiology of the embryo. In this study, we present a comprehensive single-cell transcriptome, methylome, and small RNA atlas in the day 7 human embryo. We show that, despite no change in morphology and developmental features, preimplantation glucocorticoid exposure reprograms the molecular profile of the TE lineage, and these changes are associated with an altered metabolic and inflammatory response. Our data also suggest that glucocorticoids can precociously mature the TE sublineages, supported by the presence of extravillous trophoblast markers in the polar sublineage and presence of X Chromosome dosage compensation. Further, we have elucidated that epigenetic regulation-DNA methylation and microRNAs (miRNAs)-likely underlies the transcriptional changes observed. This study suggests that exposures to exogenous compounds during preimplantation may unintentionally reprogram the human embryo, possibly leading to suboptimal development and longer-term health outcomes.

Understanding the genetic mechanisms of phenotypic variation in hybrids between domestic animals and their wild relatives may aid germplasm innovation. Here, we report the high-quality genome assemblies of a male Pamir argali (O ammon polii, 2n = 56), a female Tibetan sheep (O aries, 2n = 54), and a male hybrid of Pamir argali and domestic sheep, and the high-throughput sequencing of 425 ovine animals, including the hybrids of argali and domestic sheep. We detected genomic synteny between Chromosome 2 of sheep and two acrocentric chromosomes of argali. We revealed consistent satellite repeats around the chromosome breakpoints, which could have resulted in chromosome fusion. We observed many more hybrids with karyotype 2n = 54 than with 2n = 55, which could be explained by the selfish centromeres, the possible decreased rate of normal/balanced sperm, and the increased incidence of early pregnancy loss in the aneuploid ewes or rams. We identified genes and variants associated with important morphological and production traits (e.g., body weight, cannon circumference, hip height, and tail length) that show significant variations. We revealed a strong selective signature at the mutation (c.334C > A, p.G112W) in TBXT and confirmed its association with tail length among sheep populations of wide geographic and genetic origins. We produced an intercross population of 110 F2 offspring with varied number of vertebrae and validated the causal mutation by whole-genome association analysis. We verified its function using CRISPR-Cas9 genome editing. Our results provide insights into chromosomal speciation and phenotypic evolution and a foundation of genetic variants for the breeding of sheep and other animals.