Transcriptome analysis reveals differentially expressed genes associated with high rates of egg production in chicken hypothalamic-pituitary-ovarian axis

Abstract

The hypothalamic-pituitary-ovarian (HPO) axis regulates the breeding process cycle of laying hens. However, the key regulatory genes of the HPO axis and pathways that drive chicken egg laying performance remain elusive. A total of 856 Chinese Luhua chicken was raised and the highest two hundred and the lowest two hundred chicken egg production were considered as high egg production (HEP) and low egg production (LEP) according to the total egg number at 300 days of age, respectively. RNA-seq sequencing (RNA-Seq) was conducted to explore the chicken transcriptome from the hypothalamus, pituitary gland and ovary tissue of 6 Chinese Luhua chicken with 3 high and low-rate egg production. In total, 76.09 Gb RNA-seq sequences were generated from 15 libraries with an average of 5.07 Gb for each library. Further analysis showed that 414, 356 and 10 differentially expressed genes (DEGs) were identified in pituitary gland, ovary and hypothalamus between HEP and LEP chickens, respectively. In pituitary gland, DEGs were involve in regulation of cellular glucose homeostasis, Ras protein signal transduction, negative regulation of hormone secretion. In Ovary DEGs were mainly involved in embryonic organ development, regulation of canonical Wnt signaling, response to peptide hormone. Our study identified DEGs that regulate mTOR signaling pathway, Jak-STAT signaling pathway, Tryptophan metabolism and PI3K-Akt signaling pathways at HPO-axis in laying hens. These important data contribute to improve our understanding of reproductive biology of chicken and isolating effective molecular markers that can be used for genetic selection in Chinese domestic Luhua chicken. Traditional breeding strategies aimed to improve the chicken egg production are based on long term selection of egg number and laying rate, which are often laborious and time consuming 1. For practical breeding, quality chickens were primitively produced by indigenous chicken breeds, which are generally low egg production and slowly-growing with poor feed conversion. In certain regions of the world, there is a growing demand for slow-growing and colour-feathered quality chickens. Among them, the 'Label Rouge' in France and 'Three Yellow' in China are two famous examples. In terms of nutrition and management of chickens, rapid genetic selection can improve economic efficiency. Currently, the breeding for quality chickens in China is characterized with crossbreeding between native breeds and highly-selected lines with relatively high egg production or rapid growth rate.

Comparative Transcriptome Profiling of Ovary Tissue between Black Muscovy Duck and White Muscovy Duck with High- and Low-Egg Production

“…Recent studies have shown that the follicular development and granulosa cell survival and proliferation can be improved by regulating the expression of PI3K/Akt signaling pathway [ 65 ]. Mishra et al (2020) found that DEGs associated with high rates of egg production regulate PI3K-Akt signaling pathway at hypothalamic-pituitary-ovarian axis in laying hens [ 66 ]. The ovaries with reproductive activity are composed of small pre-hierarchical and maturing preovulatory follicles showing a hierarchy according to their size [ 67 ].…”

Transcriptome Analysis of Ovarian Follicles Reveals Potential Pivotal Genes Associated With Increased and Decreased Rates of Chicken Egg Production

“…There are five differentially expressed genes (DEGs) that were identified in the ovaries of Jinghai Yellow chickens related to egg production including ZP2 , WNT4 , AMH , IGF1 , and CYP17A1 , which serve as potential candidate genes for improving egg production ( Zhang et al, 2019 ). It was reported that 414, 356, and 10 DEGs from the hypothalamus, pituitary gland, and ovary, respectively, of the Chinese domestic Luhua chicken were potentially associated with greater rates of egg production ( Mishra et al, 2020 ). These results provided valuable information for understanding the reproductive biology of chicken and identifying effective molecular markers for genetic improvement of the domestic chicken breed.…”

Transcriptome Analysis of Ovary Tissues From Low- and High-yielding Changshun Green-shell Laying Hens

“…Improving the genetic potential of chickens is one of the most important strategies utilized to increase egg production. However, conventional breeding techniques, that are based on long-term selections using egg number and laying rate, are usually laborious and time consuming [2]. Currently, various high-throughput techniques that can identify genes at the genomic and transcriptomic levels have been increasingly employed when studying poultry reproduction.…”