Hypothalamic and pituitary transcriptome profiling using RNA-sequencing in high-yielding and low-yielding laying hens

Abstract

The reproductive physiology and laying performance of laying hens are regulated by the hypothalamus and pituitary. To understand the mechanism of egg laying regulation, we sequenced and analysed the hypothalamus and pituitary expression profiles in high- and low-yielding laying Chinese Dagu Chickens (CDC) using RNA-seq. More than 46 million clean reads and 24,873 tentative genes were obtained using the Gallus gallus genome as a reference. Transcriptome analysis in hypothalamus and pituitary revealed seven and 39 differentially expressed genes (DEGs) between high- and low-yielding CDC hens, respectively. A total of 24 and 22 DEGs were up-regulated and down-regulated, respectively, and 13 novel genes were identified. Functional annotation and pathway enrichment analysis showed that DEGs in the hypothalamus were mainly enriched in glycosaminoglycan biosynthesis. DEGs significantly enriched in the pituitary primarily affected the extracellular matrix, the protein extracellular matrix, and the extracellular space. Pathways involving phenylalanine metabolism, 2-oxocarboxylic acid metabolism, the glycosphingolipid biosynthesis-ganglion series, and local adhesion were significantly enriched in the pituitary. Eight DEGs, PRDX6 , TRIB2 , OVCH2 , CFD , Peptidase M20 , SLC7A10 , and two other amino acid transporters, are involved in the metabolism and transport of amino acids. To our knowledge, this is the first study comparing the hypothalamus and pituitary transcriptomes of high- and low-yielding laying hens. Our findings suggest that putative differences in gene expression can provide a base for further research in this field. Moreover, we identified increased expression of genes involved in amino acid metabolism, glycosaminoglycan biosynthesis, and oestrogen negative feedback systems in low-yielding laying hens, highlighting their potential as biomarkers of egg production.

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

“…In this process, the hypothalamus produces gonadotropin-releasing hormone-I (GnRH-I) which triggers pituitary gland (adenohypophysis) to release FSH and LH, and stimulates the secretion of estradiol (E2) and progesterone (P4) in ovary while ovulation 19 . Hitherto, several studies have focused to uncover the molecular mechanism associated with egg production performance in chicken 10,20,21 . However, the differential gene expression and key pathways mediating the egg production process across hypothalamic-pituitary-ovarian (HPO) axis are yet to be uncovered.…”

“…In down-regulated DEGs, significant GO terms for biological processes were response to lipid catabolic process phospholipid metabolic process, embryonic organ development, and response to extracellular stimulus. Due to the smaller number of DEGs (10) identified in thalamus tissue between HEP versus LEP chicken group, the GO term could not be assigned.…”

“…In chicken, nine transcripts expressed specifically in the hypothalamus and pituitary gland have been identified that are associated to high egg production, providing a valuable resource as molecular markers of high egg production in poultry 9 . More recently, a transcriptome study on Chinese Dagu Chickens (CDC) reported putative differences in gene expression by comparing the hypothalamus and pituitary gland 10 . However, the chicken ovarian transcriptome has not yet been completely defined, and the major regulatory genes governing oogenesis and follicle development still remain unidentified 11 .…”

Diving into the brain: deep-brain imaging techniques in conscious animals

“…This insular approach has led to an inevitable bottleneck where data on cellular and biochemical processes within specific cell types or nuclei have multiplied without a clear/tangible link to physiological function. Similarly, recent efforts in single-cell transcriptomics of the hypothalamus ( Romanov et al 2017 , Wang & Ma 2019 ) have documented a highly complex heterogenous hypothalamus, but the implication of neuropeptide expression for physiological function remains difficult to interpret without appropriate tools. Nevertheless, technological developments in genetics and systems neuroscience have enabled specific neurons to be manipulated in vivo .…”

Cuticle Secretion Duration in the Uterus Is One of the Major Factors Affecting Eggshell Cuticle Deposition in White Leghorn Laying Hens

“…PRL is generally considered to be a key factor in the onset and maintenance of broody behaviour in birds, and it has been well established that the elevated plasma PRL inhibits gonadotropin release, ovum development and ovulation, resulting poor laying performance and even complete cessation of egg production in laying hens [59][60][61][62]. Transcriptome studies have also revealed PRL is associated with egg production performance in chicken hypothalamic-pituitary-ovarian axis [63,64]. Therefore, the signi cant difference in eggshell quality (EST, ESS, eggshell weight, and cuticle opacity) and egg production performance between GC and PC group hens may be related to the different expression patterns of PRLR gene in the uterus.…”