A chromosome-level genome assembly for the Silkie chicken resolves complete sequences for key chicken metabolic, reproductive, and immunity genes.

A set of high-quality pan-genomes would help identify important genes that are still hidden/incomplete in bird reference genomes. In an attempt to address these issues, we have assembled a de novo chromosome-level reference genome of the Silkie (Gallus gallus domesticus), which is an important avian model for unique traits, like fibromelanosis, with unclear genetic foundation. This Silkie genome includes the complete genomic sequences of well-known, but unresolved, evolutionarily, endocrinologically, and immunologically important genes, including leptin, ovocleidin-17, and tumor-necrosis factor-α. The gap-less and manually annotated MHC (major histocompatibility complex) region possesses 38 recently identified genes, with differentially regulated genes recovered in response to pathogen challenges. We also provide whole-genome methylation and genetic variation maps, and resolve a complex genetic region that may contribute to fibromelanosis in these animals. Finally, we experimentally show leptin binding to the identified leptin receptor in chicken, confirming an active leptin ligand-receptor system. The Silkie genome assembly not only provides a rich data resource for avian genome studies, but also lays a foundation for further functional validation of resolved genes.

[The concepts and research progress: from heritability to microbiability].

Heritability, one of the central quantitative genetic parameters, is critically important to measure the genetic variation of traits, especially in the studies of the response to selection in evolutionary biology and agriculture, and the prediction of disease risks in medicine. The statistical model and method for estimating heritability have been continually developed and improved, since the genetic variance components was first proposed by Fisher in 1918. Recently, the term "microbiability" (m 2), an analogous concept and estimated method to heritability, was introduced in gut microbiome research for evaluating the effect of entire microbiota on a host phenotype. In this review, we summarize the progress of statistical methods in the heritability estimation, as well as the current state of gut microbiome associations with the host genome, with a particular focus on the concept and estimated methods of microbiability. Our review will provide a reference for the future study of host phenotypic variation that can be inferred by the gut microbiota.

Transcriptome sequencing identifies potential regulatory genes involved in chicken eggshell brownness.

Brown eggs are popular in many countries, and consumers regard eggshell brownness as an important indicator of egg quality. Brown eggshell color is controlled by polygene. However, the responsible genes and detailed molecular mechanisms regulating eggshell brownness have not been defined. In the present study, we applied the RNA-seq technology to analyze the transcriptome data of the shell gland epithelium of hens and investigated the candidate genes associated with eggshell brownness. The results indicated that 8461 genes were expressed in the shell gland epithelium, of which 34 genes were differentially expressed in hens laying dark vs. light brown eggs. Functional analysis revealed that two genes, ovotransferrin (TF) and heat-shock protein 70 (HSP70), as well as the oxidative phosphorylation pathway were involved in the synthesis and transport of protoporphyrin Ⅸ, which might influence the formation of eggshell brownness and result in different shades of brown.