Genome-wide variation study and inter-tissue communication analysis unveil regulatory mechanisms of egg-laying performance in chickens.

Egg-laying performance is of great economic importance in poultry, but the underlying genetic mechanisms are still elusive. In this work, we conduct a multi-omics and multi-tissue integrative study in hens with distinct egg production, to detect the hub candidate genes and construct hub molecular networks contributing to egg-laying phenotypic differences. We identifiy three hub candidate genes as egg-laying facilitators: TFPI2, which promotes the GnRH secretion in hypothalamic neuron cells; CAMK2D, which promotes the FSHß and LHß secretion in pituitary cells; and OSTN, which promotes granulosa cell proliferation and the synthesis of sex steroid hormones. We reveal key endocrine factors involving egg production by inter-tissue crosstalk analysis, and demonstrate that both a hepatokine, APOA4, and an adipokine, ANGPTL2, could increase egg production by inter-tissue communication with hypothalamic-pituitary-ovarian axis. Together, These results reveal the molecular mechanisms of multi-tissue coordinative regulation of chicken egg-laying performance and provide key insights to avian reproductive regulation.

The role of AdipoQ on proliferation, apoptosis, and hormone Secretion in chicken primary adenohypophysis cells.

Adiponectin (AdipoQ), an adipokine secreted by adipocytes, has been reported to exist widely in various cell types and tissues, including the adenohypophysis of chickens. However, the molecular mechanism by which AdipoQ regulates the function of chicken adenohypophysis remains elusive. In this study, we investigated the effects of AdipoQ on proliferation, apoptosis, secretion of related hormones (FSH, LH, TSH, GH, PRL and ACTH) and expression of related genes (FSHß, LHß, GnRHR, TSHß, GH, PRL and ACTH) in primary adenohypophysis cells of chickens by using real-time fluorescent quantitative PCR (RT-qPCR), cell counting kit-8 (CCK-8), flow cytometry, enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) assays. Our results showed that AdipoQ promoted the proliferation of chicken primary adenohypophysis cells, up-regulated the mRNA expression of proliferation-related genes CDK1, PCNA, CCND1 and P21 (P < 0.05), as well as the increased protein expression of CDK1 and PCNA (P < 0.05). Furthermore, AdipoQ inhibited apoptosis of chicken primary adenohypophysis cells, resulting in down-regulation of pro-apoptotic genes Caspase3, Fas, and FasL mRNA expression, and decreased Caspase3 protein expression (P < 0.05). Moreover, there was an up-regulation of anti-apoptotic gene Bcl2 mRNA and protein expression (P < 0.05). Additionally, AdipoQ suppressed the secretion of FSH, LH, TSH, GH, PRL, and ACTH (P < 0.05), as well as the mRNA expression levels of related genes (P < 0.05). Treatment with AdipoRon (a synthetic substitute for AdipoQ) and co-treatment with RNA interference targeting AdipoQ receptors 1/2 (AdipoR1/2) had no effect on the secretion of FSH, LH, TSH, GH, PRL, and ACTH, as well as the mRNA expression levels of the related genes. This suggests that AdipoQ's regulation of hormone secretion and related gene expression is mediated by the AdipoR1/2 signaling axis. Importantly, we further demonstrated that the mechanism of AdipoQ on FSH, LH, TSH and GH secretion is realized through AMPK signaling pathway. In conclusion, we have revealed, for the first time the molecular mechanism by which AdipoQ regulates hormone secretion in chicken primary adenohypophysis cells.

Dynamic alternations of three-dimensional chromatin architecture contribute to phenotypic characteristics of breast muscle in chicken.

Breast muscle growth rate and intramuscular fat (IMF) content show apparent differences between fast-growing broilers and slow-growing indigenous chickens. However, the underlying genetic basis of these phenotypic characteristics remains elusive. In this study, we investigate the dynamic alterations of three-dimensional genome architecture and chromatin accessibility in breast muscle across four key developmental stages from embryo to starter chick in Arbor Acres (AA) broilers and Yufen (YF) indigenous chickens. The limited breed-specifically up-regulated genes (Bup-DEGs) are embedded in breed-specific A compartment, while a majority of the Bup-DEGs involving myogenesis and adipogenesis are regulated by the breed-specific TAD reprogramming. Chromatin loops allow distal accessible regions to interact with myogenic genes, and those loops share an extremely low similarity between chicken with different growth rate. Moreover, AA-specific loop interactions promote the expression of 40 Bup-DEGs, such as IGF1, which contributes to myofiber hypertrophy. YF-specific loop interactions or distal accessible regions lead to increased expression of 5 Bup-DEGs, including PIGO, PEMT, DHCR7, TMEM38B, and DHDH, which contribute to IMF deposition. These results help elucidate the regulation of breast muscle growth and IMF deposition in chickens.

A Bidirectional Quasi-Endfire Patch Antenna with Low Elevation Angle.

A bidirectional quasi-endfire patch antenna with a low elevation angle has promising applications for wireless communication systems that are vehicle-based, airborne, and shipborne. In this paper, the shortened patch resonators and open patch resonator are integrated to form a bidirectional quasi-endfire patch antenna with low elevation angle. The open patch resonator operates with a TM20 mode to realize bidirectional radiation. The two shortened patch resonators operate with a TM01 mode coupled with a TM20 mode to control the phase difference between them at a suitable angle, so that the shortened patch resonators act as directors to tilt the dual beams toward the endfire direction and achieve low elevation angle. Compared with reported patch antennas with dual beams, the proposed antenna has the lowest elevation angle and a compact structure. For demonstration purposes, an antenna prototype operating at 3.5 GHz is fabricated and measured, exhibiting a low elevation angle of ±28°, a -10 dB impedance matching bandwidth from 3.44 GHz to 3.61 GHz, and a size of 1.36 λ0 × 0.57 λ0 with a profile of 0.036 λ0. A prototype with two pair of shortened patch directors further reduces the elevation angle to ±19° with the size of 2.3 λ0 × 0.57 λ0.

Duck pan-genome reveals two transposon insertions caused bodyweight enlarging and white plumage phenotype formation during evolution.

Structural variations (SVs) are a major source of domestication and improvement traits. We present the first duck pan-genome constructed using five genome assemblies capturing ∼40.98 Mb new sequences. This pan-genome together with high-depth sequencing data (∼46.5×) identified 101,041 SVs, of which substantial proportions were derived from transposable element (TE) activity. Many TE-derived SVs anchoring in a gene body or regulatory region are linked to duck's domestication and improvement. By combining quantitative genetics with molecular experiments, we, for the first time, unraveled a 6945 bp Gypsy insertion as a functional mutation of the major gene IGF2BP1 associated with duck bodyweight. This Gypsy insertion, to our knowledge, explains the largest effect on bodyweight among avian species (27.61% of phenotypic variation). In addition, we also examined another 6634 bp Gypsy insertion in MITF intron, which triggers a novel transcript of MITF, thereby contributing to the development of white plumage. Our findings highlight the importance of using a pan-genome as a reference in genomics studies and illuminate the impact of transposons in trait formation and livestock breeding.

Fasting-Induced Molting Impacts the Intestinal Health by Altering the Gut Microbiota.

Fasting-induced molting (FIM) is a common method used to improve the laying performance of aged laying hens. Nevertheless, this approach may impose various stresses on chickens, such as disruptions in intestinal flora and inflammation issues within the intestines. However, the impact of an imbalance in intestinal flora on intestinal health during the FIM process remains elusive. Therefore, intestinal injury, the microbiome, and the metabolome were analyzed individually and integrated to elucidate the impact of the intestinal flora on intestinal health during the FIM process. The findings indicated that fasting resulted in a notable reduction in villus height and villus/crypt ratio, coupled with elevated levels of intestinal inflammation and permeability. During the fasting period, microbiota compositions changed. The abundance of Escherichia_Shigella increased, while the abundance of Ruminococcaceae_UCG-013 and Lactobacillus decreased. Escherichia_Shigella was positively correlated with Citrinin and Sterobilin, which lead to intestinal inflammation. Ruminococcaceae_UCG-013 and Lactobacillus exhibited positive correlations with Lanthionine and reduced Glutathione, thereby reducing intestinal inflammation. This study screened the intestinal probiotics, Ruminococcaceae UCG-013 and Lactobacillus, that influence gut health during the fasting period, providing an experimental basis for improving gut microbiota and reducing intestinal inflammation during the FIM process.

Estrogen promotes gonadotropin-releasing hormone expression by regulating tachykinin 3 and prodynorphin systems in chicken.

The "KNDy neurons" located in the hypothalamic arcuate nucleus (ARC) of mammals are known to co-express kisspeptin, neurokinin B (NKB), and dynorphin (DYN), and have been identified as key mediators of the feedback regulation of steroid hormones on gonadotropin-releasing hormone (GnRH). However, in birds, the genes encoding kisspeptin and its receptor GPR54 are genomic lost, leaving unclear mechanisms for feedback regulation of GnRH by steroid hormones. Here, the genes tachykinin 3 (TAC3) and prodynorphin (PDYN) encoding chicken NKB and DYN neuropeptides were successfully cloned. Temporal expression profiling indicated that TAC3, PDYN and their receptor genes (TACR3, OPRK1) were mainly expressed in the hypothalamus, with significantly higher expression at 30W than at 15W. Furthermore, overexpression or interference of TAC3 and PDYN can regulate the GnRH mRNA expression. In addition, in vivo and in vitro assays showed that estrogen (E2) could promote the mRNA expression of TAC3, PDYN, and GnRH, as well as the secretion of GnRH/LH. Mechanistically, E2 could dimerize the nuclear estrogen receptor 1 (ESR1) to regulate the expression of TAC3 and PDYN, which promoted the mRNA and protein expression of GnRH gene as well as the secretion of GnRH. In conclusion, these results revealed that E2 could regulate the GnRH expression through TAC3 and PDYN systems, providing novel insights for reproductive regulation in chickens.

Whole-transcriptome sequencing reveals a melanin-related ceRNA regulatory network in the breast muscle of Xichuan black-bone chicken.

The economic losses incurred due to reduced muscle pigmentation highlight the crucial role of melanin-based coloration in the meat of black-bone chickens. Melanogenesis in the breast muscle of black-bone chickens is currently poorly understood in terms of molecular mechanisms. This study employed whole-transcriptome sequencing to analyze black and white breast muscle samples from black-bone chickens, leading to the identification of 367 differentially expressed (DE) mRNAs, 48 DElncRNAs, 104 DEcircRNAs, and 112 DEmiRNAs involved in melanin deposition. Based on these findings, a competitive endogenous RNA (ceRNA) network was developed to better understand the complex mechanisms of melanin deposition. Furthermore, our analysis revealed key DEmRNAs (TYR, DCT, EDNRB, MLPH and OCA2) regulated by DEmiRNAs (gga-miR-140-5p, gga-miR-1682, gga-miR-3529, gga-miR-499-3p, novel-m0012-3p, gga-miR-200b-5p, gga-miR-203a, gga-miR-6651-5p, gga-miR-7455-3p, gga-miR-31-5p, miR-140-x, miR-455-x, novel-m0065-3p, gga-miR-29b-1-5p, miR-455-y, novel-m0085-3p, and gga-miR-196-1-3p). These DEmiRNAs competitively interacted with DElncRNAs including MSTRG.2609.2, MSTRG.4185.1, LOC112530666, LOC112533366, LOC771030, LOC107054724, LOC121107411, LOC100859072, LOC101750037, LOC121108550, LOC121109224, LOC121110876, and LOC101749016, as well as DEcircRNAs, such as novel_circ_000158, novel_circ_000623, novel_001518, and novel_circ_003596. The findings from this study provide insight into the mechanisms that regulate lncRNA, circRNA, miRNA, and mRNA expression in chicken melanin deposition.