The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens

The potential influence of genome-wide adaptive divergence on conservation translocation outcome in an isolated greater sage-grouse population

Conservation translocations are an important conservation tool commonly employed to augment declining or reestablish extirpated populations. One goal of augmentation is to increase genetic diversity and reduce the risk of inbreeding depression (i.e., genetic rescue). However, introducing individuals from significantly diverged populations risks disrupting coadapted traits and reducing local fitness (i.e., outbreeding depression). Genetic data are increasingly more accessible for wildlife species and can provide unique insight regarding the presence and retention of introduced genetic variation from augmentation as an indicator of effectiveness and adaptive similarity as an indicator of source and recipient population suitability. We used 2 genetic data sets to evaluate augmentation of isolated populations of greater sage-grouse (Centrocercus urophasianus) in the northwestern region of the species range (Washington, USA) and to retrospectively evaluate adaptive divergence among source and recipient populations. We developed 2 statistical models for microsatellite data to evaluate augmentation outcomes. We used one model to predict genetic diversity after augmentation and compared these predictions with observations of genetic change. We used the second model to quantify the amount of observed reproduction attributed to transplants (proof of population integration). We also characterized genome-wide adaptive divergence among source and recipient populations. Observed genetic diversity (HO = 0.65) was higher in the recipient population than predicted had no augmentation occurred (HO = 0.58) but less than what was predicted by our model (HO = 0.75). The amount of shared genetic variation between the 2 geographically isolated resident populations increased, which is evidence of periodic gene flow previously assumed to be rare. Among candidate adaptive genes associated with elevated fixation index (FST) (143 genes) or local environmental variables (97 and 157 genes for each genotype-environment association method, respectively), we found clusters of genes with related functions that may influence the ability of transplants to use local resources and navigate unfamiliar environments and their reproductive potential, all possible reasons for low genetic retention from augmentation.

Integrating genomics and transcriptomics to identify candidate genes for high-altitude adaptation and egg production in Nixi chicken

1. This study combined genome-wide selection signal analysis with RNA-sequencing to identify candidate genes associated with high altitude adaptation and egg production performance in Nixi chickens (NXC).2. Based on the whole-genome data from 20 NXC (♂:10; ♀:10), the population selection signal was analysed by sliding window analysis. The selected genes were screened by combination with the population differentiation statistic (FST). The sequence diversity statistic (θπ). RNA-seq was performed on the ovarian tissues of NXC (n = 6) and Lohmann laying hens (n = 6) to analyse the differentially expressed genes (DEGs) between the two groups. The functional enrichment analysis of the selected genes and differentially expressed genes was performed.3. There were 742 genes under strong positive selection and 509 differentially expressed genes screened in NXC. Integrated analysis of the genome and transcriptome revealing 26 overlapping genes. The candidate genes for adaptation to a high-altitude environment, as well as for egg production, disease resistance, vision and pigmentation in NXC were preliminarily screened.4. The results provided theoretical guidance for further research on the genetic resource protection and utilisation of NXC.

Ovary metabolome and cecal microbiota changes in aged laying hens supplemented with vitamin E

This study was aimed to evaluate the effect of vitamin E (VE) on laying performance, VE deposition, antioxidant capacity, immunity, follicle development, estrogen secretion, ovary metabolome, and cecal microbiota of laying hens. One hundred and twenty XinYang Black-Feathered laying hens (70 wk old) were randomly assigned to 2 groups (6 replicates of 20 birds), and fed a basal diet (containing 20 mg/kg VE, control (CON) group) and a basal diet supplemented with 20 mg/kg VE (VE group). The experiment lasted for 10 wk. Results showed that VE supplementation increased laying performance, antioxidant capacity, and immunity, as evidenced by increased (P < 0.05) performance (laying rate), antioxidant (glutathione peroxidase, total superoxide dismutase, total antioxidant capacity, and catalase) and immune (immunoglobulins) parameters, and decreased (P < 0.05) feed/egg ratio and malondialdehyde. Meanwhile, VE group had higher (P < 0.05) pregrade follicles, ovary index and serum estrogen levels than CON group. 16S rRNA sequencing showed that VE supplementation altered the cecal microbiota composition by increasing Bacteroides, Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-001 and Megamonas abundances and reducing Christensenellaceae_R-7_group abundance (at genus level), which are mainly associated with the production of short-chain fatty acids. Metabolomic profiling of the ovary revealed that the major metabolites altered by VE supplementation were mainly related to follicle development, estrogen secretion, anti-inflammatory, antioxidant, phototransduction, bile acid synthesis, and nutrient transport. Furthermore, changes in cecal microbiota (at genus level) and ovary metabolites were highly correlated with laying performance, antioxidant, and immune parameters. In summary, VE contributed to the laying performance of aged laying hens by enhancing antioxidant, immune, and ovarian functions, promoting follicle development and estrogen secretion, and regulating gut microbiota and ovary metabolites. These findings will provide a new perspective on the mechanisms of egg production in aged poultry ovaries.

Effects of dietary supplementation of glycerol monolaurate on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens

The objective of this study was to evaluate the effects of different levels of glycerol monolaurate (GML) on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens. A total of 480 Hy-Line Variety Brown hens (age 54 wk) were randomly assigned to 5 treatments: the control group (basal diet) and 4 GML groups (basal diet supplemented with 100, 200, 300, and 400 mg/kg GML). Each treatment consisted of 8 replicates with 12 hens each and the trial lasted for 8 wk. The results showed that dietary inclusion of GML increased the ADFI in the entire experimental period and the average egg weight in wk 5 to 8 and wk 1 to 8 of the experiment (linear, P < 0.05). Dietary GML addition linearly increased albumen height, Haugh unit and yolk color, and quadratically increased eggshell thickness (P < 0.05). The serum SOD activity, T-AOC and IgG concentrations in the 200 mg/kg GML group, and GSH-Px activity in 200 and 300 mg/kg GML groups were increased, while the MDA concentration in 200 and 300 mg/kg GML groups was decreased than those in the control group (P < 0.05). The jejunal villus height and villus height: crypt depth in 300 mg/kg GML group were higher than that in the control group (P < 0.05). The mRNA expression of TLR4, IL-1β and TNF-α in spleen and jejunum decreased with the increase of dietary GML concentration (linear, P < 0.05). In conclusion, dietary GML supplementation could improve egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens, and dietary 300 mg/kg GML inclusion is suggested.

Strand-Specific RNA Sequencing Reveals Gene Expression Patterns in F1 Chick Breast Muscle and Liver after Hatching

Heterosis refers to the phenomenon where hybrids exhibit superior performance compared to the parental phenotypes and has been widely utilized in crossbreeding programs for animals and crops, yet the molecular mechanisms underlying this phenomenon remain enigmatic. A better understanding of the gene expression patterns in post-hatch chickens is very important for exploring the genetic basis underlying economically important traits in the crossbreeding of chickens. In this study, breast muscle and liver tissues (n = 36) from full-sib F1 birds and their parental pure lines were selected to identify gene expression patterns and differentially expressed genes (DEGs) at 28 days of age by strand-specific RNA sequencing (ssRNA-seq). This study indicates that additivity is the predominant gene expression pattern in the F1 chicken post-hatch breast muscle (80.6% genes with additivity) and liver (94.2% genes with additivity). In breast muscle, Gene Ontology (GO) enrichment analysis revealed that a total of 11 biological process (BP) terms closely associated with growth and development were annotated in the identified DEG sets and non-additive gene sets, including STAT5A, TGFB2, FGF1, IGF2, DMA, FGF16, FGF12, STAC3, GSK3A, and GRB2. Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation presented that a total of six growth- and development-related pathways were identified, involving key genes such as SLC27A4, GLUL, TGFB2, COX17, and GSK3A, including the PPAR signaling pathway, TGF-beta signaling pathway, and mTOR signaling pathway. Our results may provide a theoretical basis for crossbreeding in domestic animals.

Dietary restriction and life-history trade-offs: insights into mTOR pathway regulation and reproductive investment in Japanese quail

Resources are needed for growth, reproduction and survival, and organisms must trade off limited resources among competing processes. Nutritional availability in organisms is sensed and monitored by nutrient-sensing pathways that can trigger physiological changes or alter gene expression. Previous studies have proposed that one such signalling pathway, the mechanistic target of rapamycin (mTOR), underpins a form of adaptive plasticity when individuals encounter constraints in their energy budget. Despite the fundamental importance of this process in evolutionary biology, how nutritional limitation is regulated through the expression of genes governing this pathway and its consequential effects on fitness remain understudied, particularly in birds. We used dietary restriction to simulate resource depletion and examined its effects on body mass, reproduction and gene expression in Japanese quails (Coturnix japonica). Quails were subjected to feeding at 20%, 30% and 40% restriction levels or ad libitum for 2 weeks. All restricted groups exhibited reduced body mass, whereas reductions in the number and mass of eggs were observed only under more severe restrictions. Additionally, dietary restriction led to decreased expression of mTOR and insulin-like growth factor 1 (IGF1), whereas the ribosomal protein S6 kinase 1 (RPS6K1) and autophagy-related genes (ATG9A and ATG5) were upregulated. The pattern in which mTOR responded to restriction was similar to that for body mass. Regardless of the treatment, proportionally higher reproductive investment was associated with individual variation in mTOR expression. These findings reveal the connection between dietary intake and the expression of mTOR and related genes in this pathway.

A systematic review of potential productivity, egg quality, and animal welfare implications of extended lay cycles in commercial laying hens in Canada

Lay cycle lengths in the Canadian egg industry are currently 50 to 52 wk (68-70 wk of age). In light of increased productivity in commercial laying hens over the last few decades, the much longer lay cycle lengths already implemented in other countries, extending lay cycle lengths in Canada, should be considered with careful attention to potential environmental, economic, and animal welfare implications. However, there is a lack of information in the public domain that provides robust evidence of performance levels and potential trade-offs to support comprehensive consideration of the desirability of extending lay cycles beyond current Canadian norms. Hence, a systematic literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was undertaken. Data collection focused primarily on information related to feed-, flock management-, and hen genetics/physiology-related interventions that were studied in literature to support extension of lay cycles (review objective 1), and compiling and analyzing productivity, egg quality, and animal welfare outcomes reported at 70 wk of age or beyond (review objective 2). Several feed-related interventions such as high-protein diets, and probiotics supplements, and flock management interventions such split-feeding were found to potentially improve productivity, and especially egg quality, outcomes in the late laying phase. More studies with bigger flock sizes and in commercial lay facilities need to be undertaken before any of these interventions can be definitively recommended for commercial egg production. Under objective 2, productivity was found to be at acceptable levels well beyond 70 wk of age. Performance on most egg quality traits and animal welfare indicators were also at acceptable levels past 70 wk of age but increased variability was observed beyond ∼80 wk of age. There were also inconclusive indications on how hens in caged housing and white laying hens fare relative to hens in noncaged housing and brown-type layers during the late laying phase. Economic data were limited but suggested that lay cycle lengths beyond 90 wk might not generated net economic benefits.

Transcriptome Analysis of Granulosa Cells Reveals Regulatory Mechanisms Related to Chicken Follicle Development

In this study, we aimed to better understand the difference between the functions of the two types of granulosa cells and sought to discover more key genes involved in follicle development and follicle selection. Herein, we separately collected pre-hierarchical follicle granulosa cells (PHGCs) and preovulatory follicle granulosa cells (POGCs) for RNA extraction; the transcriptomes of the two groups were compared via RNA-seq. A total of 5273 differentially expressed genes (DEGs) were identified between the PHGCs and POGCs; 2797 genes were up-regulated and 2476 were down-regulated in the PHGCs compared with the POGCs. A qPCR analysis confirmed that the expression patterns of 16 randomly selected DEGs were highly consistent with the RNA-seq results. In the POGCs, many of the genes with the most significant increase in expression were related to steroid hormone synthesis. In addition, the genes with the most significant decline in expression, including AMH and WT1, were related to the inhibition of steroid hormone synthesis. These results suggest that steroid hormones play a key role in follicle development. Furthermore, a Gene Ontology (GO) analysis revealed that these DEGs were mainly involved in the primary metabolic process, the carbohydrate metabolic process, the cellular process, ribosomes, the cytoplasm, and intracellular processes. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEGs were mainly enriched in steroid biosynthesis, the cell cycle, ribosomes, the TGF-beta signaling pathway, focal adhesion, and so on. We also observed the morphology of the follicles at different developmental stages, and the results showed that the thickness of the granular layer of the small yellow follicles (SYFs) decreased significantly with further development. In addition, we also found that the thickness of the granulosa layer of hens over 300 days old was significantly lower than that of 200-day-old hens. In short, these data indicate that the tissue morphology and function of granulosa cells change throughout follicle development.

mTOR signalling pathway in stem cell bioactivities and angiogenesis potential

The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.

The improving effect of soybean isoflavones on ovarian function in older laying hens

Emerging evidence suggests an association between estrogen levels and reduced egg-laying performance as the layer became old. Since soy isoflavones (SF) have estrogen-mimic effects, whether it can enhance production performance and ovarian function of older layers is still not known. A total of 160 Lohmann pink layers (66-wk-old) were used in a 2 × 2 factorial design, which included 2 egg-laying levels [low (76.89 ± 1.65%; LOW) and normal (84.96 ± 1.01%; NOR)] and 2 different dietary groups [0 mg/kg SF, 20 mg/kg SF] were used. The results showed the NOR group had higher egg-laying rate, egg mass, and feed efficiency during the all phases (P(laying) < 0.05). The unqualified egg rate was lower in NOR group (9-12 wk, 1-12 wk) (P(laying) < 0.05). Dietary supplementation with SF increased the egg-laying rate and feed efficiency (5-8 wk, 9-12 wk, 1-12 wk), increased egg mass (9-12 wk, 1-12 wk) (P(SF) < 0.05). The NOR layers presented higher eggshell quality (redness, yellowness, brightness, eggshell ratio) at 12 wk (P(laying) < 0.05). Eggshell quality was found to be improved by SF (eggshell strength and eggshell thickness), egg albumen quality (higher albumen height and Haugh unit) at 12 wk (P(SF) < 0.05). Supplementing with SF led to an increase in eggshell strength in LOW group (P(laying*SF) < 0.05). The higher serum lever of glucose (GLU) and lower serum lever of follicle stimulating hormone (FSH) were in NOR group (P(laying) < 0.05). Supplementing SF in diets increased serum of estradiol (E2) and insulin-like growth factors-1 (IGF-1), decreased serum of FSH (P(SF) < 0.05). The NOR layers presented lower estrogen receptor α (ERα), estrogen receptor β (ERβ), B lymphoma 2 associated X protein (Bax), cytochrome c (Cytc), interleukin 6 (IL-6), caspase3, caspase9, IKKα, P50, and P65 expression in the ovary (P(laying) < 0.05). Dietary SF supplementation decreased the anti-Müllerian hormone receptor (AMHR), Bax, caspase3, caspase9, Cytc, IL-6, IKKα, P50, P65 expression in the ovary (P(SF) < 0.05). These findings indicated that layers with NOR group had higher production performance, egg quality, and ovarian function, while dietary supplementation with SF improved production performance and ovarian function by reducing inflammation and apoptosis-related genes expression in ovary.

Effects of Bacillus subtilis Natto NB205 and Its Mutant NBMK308 on Egg Quality in Aging Laying Hens

In aging laying hens, reproductive changes reduce egg quality. Bacillus subtilis natto (B. subtilis) is a versatile bacterium with high vitamin K2 content, providing health benefits for animals and humans. This study investigated the effect of B. subtilis natto NB205 and its mutant NBMK308 on egg quality in aging laying hens. Results showed that NB205 and NBMK308 supplementation significantly improved albumen height (p < 0.001), Haugh units (p < 0.05), and eggshell thickness (p < 0.001) compared to the control group. Supplementation also increased ovalbumin expression, regulated tight junction (TJ) proteins, reduced pro-inflammatory cytokine levels, and improved the health and productivity of aging laying hens by regulating key apoptosis-related genes in the magnum part of the oviduct. There were differences in the expression of vitamin K-dependent proteins (VKDPs) in the magnum between NB205 and NBMK308, but no significant differences in the improvement of egg quality. Supplementation with NB205 and NBMK308 can improve egg quality in aging laying hens.

Melatonin alleviates ovarian function damage and oxidative stress induced by dexamethasone in the laying hens through FOXO1 signaling pathway

Oxidative stress can trigger follicular atresia, and decrease follicles quantity in each development stage, thereby alleviating reproductive activity. The induction of oxidative stress in chickens through intraperitoneal injection of dexamethasone is a reliable and stable method. Melatonin has been shown to mitigate oxidative stress in this model, but the underlying mechanism remains unclear. Therefore, this study aimed to investigate whether melatonin can recover aberrant antioxidant status induced by dexamethasone and the specific mechanism behind melatonin-dependent protection. A total of 150 healthy 40-wk-old Dawu Jinfeng laying hens with similar body weights and laying rates were randomly divided into three groups, with five replicates per group and 10 hens per replicate. The hens in the control group (NS) received intraperitoneal injections of normal saline for 30 d, the dexamethasone group (Dex+NS) received 20 mg/kg dose of dexamethasone for the first 15 d, followed by the 15 d of normal saline treatment. While in the melatonin group (Dex+Mel), dexamethasone (20 mg/kg dose) was injected intraperitoneally in the first 15 d, and melatonin (20 mg/kg/d) was injected in the last 15 d. The results showed that dexamethasone treatment significantly enhanced oxidative stress (P < 0.05), while melatonin not only inhibited the oxidative stress but also notably enhanced the antioxidant enzymes superoxide dismutase (SOD), catalase activity (CAT), glutathione peroxidase (GSH-Px), and antioxidant genes CAT, superoxide dismutase 1 (SOD1), glutathione peroxidase 3 (GPX3), and recombinant peroxiredoxin 3 (PRDX3) expression (P < 0.05). Melatonin treatment also markedly reduced 8-hydroxy deoxyguanosine (8-OHdG), malondialdehyde (MDA), and reactive oxygen species (ROS) levels (P < 0.05) and apoptotic genes Caspase-3, Bim, and Bax in the follicle. In the Dex+Mel group, the Bcl-2 and SOD1 protein levels were also increased (P < 0.05). Melatonin inhibited the forkhead Box Protein O1 (FOXO1) gene and its protein expression (P < 0.05). In general, this investigation revealed that melatonin might decrease oxidative stress and ROS by enhancing antioxidant enzymes and genes, activating the antiapoptotic genes, and inhibiting the FOXO1 pathway in laying hens.

Dietary naringin supplementation on hepatic yolk precursors formation and antioxidant capacity of Three-Yellow breeder hens during the late laying period

In this study, the effects of naringin on hepatic yolk precursors formation and antioxidant capacity of Three-Yellow breeder hens during late laying period were evaluated. A total of 480 (54-wk-old) Three-Yellow breeder hens were randomly assigned to 4 groups (6 replicates of 20 hens): nonsupplemented control diet (C), and control diet supplemented with 0.1%, 0.2%, and 0.4% of naringin (N1, N2, and N3), respectively. Results showed that dietary supplemented with 0.1%, 0.2%, and 0.4% of naringin for 8 wk promoted the cell proliferation and attenuated the excessive fat accumulation in the liver. Compared with C group, increased concentrations of triglyceride (TG), total cholesterol (T-CHO), high-density lipoprotein cholesterol (HDL-C), and very low-density lipoprotein (VLDL), and decreased contents of low-density lipoprotein cholesterol (LDL-C) were detected in liver, serum and ovarian tissues (P < 0.05). After 8 wk of feeding with naringin (0.1%, 0.2%, and 0.4%), serum estrogen (E₂) level, expression levels of proteins and genes of estrogen receptors (ERs) increased significantly (P < 0.05). Meanwhile, naringin treatment regulated expression of genes related to yolk precursors formation (P < 0.05). Furthermore, dietary naringin addition increased the antioxidants, decreased the oxidation products, and up-regulated transcription levels of antioxidant genes in liver tissues (P < 0.05). These results indicated that dietary supplemented with naringin could improve hepatic yolk precursors formation and hepatic antioxidant capacity of Three-Yellow breeder hens during the late laying period. Doses of 0.2% and 0.4% are more effective than dose of 0.1%.

Effects of dietary theabrownins on production performance, egg quality and ovarian function of laying hens with different ages

This experiment was conducted to investigate the effect of theabrownins (TB) on production performance, egg quality, and ovarian function of laying hens at different ages. A total of 240 Lohmann laying hens were assigned in a 2 × 2 factorial design, which encompassed 2 layers ages (47-wk-old and 67-wk-old) and 2 dietary levels of TB (0 and 100 mg/kg) for 12 wk. Results showed that older layers had lower laying rate, egg mass, and higher feed-to-egg ratio (F/E), egg weight and unqualified egg rate than the younger layers (P_(AGE) < 0.01) during all the experimental period. The effect of TB was found to increase egg laying rate and feed efficiency during 5 to 8 wk, 9 to 12 wk and the overall phases and decreased unqualified egg rate during 1 to 4 wk and the overall phases (P_(TB) ≤ 0.05). The eggshell quality (strength, thickness), albumen quality (albumen height and Haugh unit) of eggs from older layers were decreased during overall phases (P_(AGE) ≤ 0.05). TB increased eggshell strength during all phases and enhanced eggshell thickness at the end of wk 4 and 8 and increased albumen height and Haugh unit at the end of wk 8 and 12 of older layers (P_{(Interaction)} ≤ 0.05). In addition, TB also increased egg quality of older layers after 14 d storage. A decrease in the serum concentration of progesterone, melatonin, follicle stimulating hormone, estradiol was observed in the older compared to the younger ones (P_(AGE) < 0.05), while the increase in serum concentration of progesterone, melatonin, anti-Müllerian hormone (AMH) were more emphasized when older hens received TB supplemented diet (P_{(Interaction)} < 0.05). The older layer demonstrated lower the concentration of glutathione (GSH) (P_(AGE) < 0.05). And the activity of glutathione-s-transferase (GST) was significantly decreased in layers under 67-wk-old (P_(AGE) <0.05). The increase in concentration of GSH and the decrease in concentration of malondialdehyde (MDA) were more pronounced when TB were supplemented in 67-wk-old layers (P_{(Interaction)} ≤ 0.05). Layers at 67-wk-old had lower mRNA expression of Heme oxygenase 1 (HO-1) (P_(AGE) < 0.01) in ovary. Dietary TB supplementation upregulated mRNA gene expression of HO-1, Nuclear factor E2 related factor 2 (Nrf2), Quinone oxidoreductase 1 (NQO1) (P_(TB) < 0.01). Dietary TB upregulated mRNA expression of ovarian reproductive hormone receptor (estrogen receptor 1 [ESR1] and steroidogenic acute regulatory protein 1 [StAR1]]; P_(TB) < 0.01). The results suggest feeding TB (100 mg/kg) could improve the egg production rate, egg quality, and antioxidant capacity of the ovary. Moreover, the effect of TB was more pronounced in older layers (64-wk-old vs. 47-wk-old).

Untargeted Metabolomics Revealed Potential Biomarkers of Small Yellow Follicles of Chickens during Sexual Maturation

Sexual maturation provides economically important traits in poultry production. Research on the initiation mechanism of sexual maturity is of great significance for breeding high-yield laying hens. However, the underlying mechanisms are not fully clear. Here, one hundred and fifty Chahua No. 2 laying hens (the CH2 group, which has precocious puberty) and one hundred and fifty Wu Liang Shan black-bone laying hens (the WLS group, a late-maturing chicken breed) with similar weights and ages were randomly selected. ELISA was used to determine the secretion levels of luteinizing hormone (LH), estradiol (E2), and progesterone (P4) in 150-day-old serum and small yellow follicle (SYF) tissues. A histology examination, immunohistochemistry, and quantitative real-time PCR (qPCR) were used to explore the molecular mechanism of how some genes related to oxidative stress affect sexual maturation. The results showed that the secretion levels of LH, E2, and P4 in the CH2 group serum and SYF were higher than those in the WLS group. The results of the real-time PCR of all genes showed that the expression levels of cytochrome P450 family 11 subfamily A member 1, steroidogenic acute regulatory protein, follicle-stimulating hormone receptor, and cytochrome P450 family 19 subfamily A member 1 in the CH2 group were significantly higher than those in the WLS groups (p < 0.001). Untargeted metabolomics combined with multivariate statistical analysis was used to identify biomarkers of SYF tissues in the CH2 and WLS groups. A trajectory analysis of the principal component analysis (PCA) results showed that the samples within the group were clustered and that the samples were dispersed between the CH2 and the WLS groups, indicating that the results of the measured data were reliable and could be used for further research. Further analysis showed that a total of 319 metabolites in small yellow follicles of the CH2 and WLS groups were identified, among which 54 downregulated differential metabolites were identified. These 54 metabolites were found as potential CH2 biomarkers compared with WLS at 150 days, and the different expressions of L-arginine, L-prolinamide, (R)-4-hydroxymandelate, glutathione, and homovanillic acid were more significant. Twenty metabolic pathways were found when significantly differential metabolites were queried in the KEGG database. According to the impact values of the metabolic pathways, eighteen differential metabolites belonged to the mTOR signaling pathway, glutathione metabolism, ABC transporters, the cell ferroptosis pathway, and D-arginine and D-ornithine metabolism. Interestingly, we identified that the cell ferroptosis pathway played an important role in chicken follicle selection for the first time. The histology and immunohistochemistry of SYF showed that the number of granulosa cells increased in the CH2 groups and the expression levels of glutathione peroxidase 4, tumor protein p53, ribosomal protein S6 kinase, and sterol regulatory element binding protein 1 in the granulosa cell layer were upregulated in the CH2 group at the time of sexual maturation. Furthermore, we also speculated that the antioxidant system may play an indispensable role in regulating sexual maturity in chickens. Overall, our findings suggest differentially expressed metabolites and metabolic pathways between CH2 and WLS chickens, providing new insights into the initiation mechanism of sexual maturation.

Dietary phytogenic inclusion level affects production performance and expression of ovarian cytoprotective genes in laying hens

A 12-wk study was conducted to investigate the effects of a phytogenic premix (PP) inclusion level on production performance, and the expression of genes relevant for detoxification (aryl hydrocarbon receptor; AhR) and antioxidant capacity (Nuclear factor erythroid 2-related factor 2; Nrf2) in the ovaries of laying hens. The PP consisted of bioactive substances derived from ginger, lemon balm, oregano, and thyme substances (Anco FIT-Poultry). Depending on PP inclusion level (i.e., 0, 500, 750, 1,000, and 1,500 mg/kg diet) in the basal diet, 385 laying hens Hy-Line Brown, 20-wk-old were assigned into 5 treatments: CON, P500, P750, P1000, and P1500, with 7 replicates of 11 hens with ad libitum access to feed and water. Performance parameters were closely monitored on a weekly basis and analyzed in the following 3 experimental periods: 1 to 4 wk, 5 to 8 wk, and 9 to 12 wk of treatment administration (i.e., 21-24, 25-28, and 29-32 wk of layers age, respectively). At the end of the 8th and 12th wk of the experiment (i.e., 28 and 32 wk of layers age), a layer from each replicate was selected, euthanized, the ovaries sampled and stored deep frozen until gene expression analysis. Data were analyzed by ANOVA and means compared using Tukey's honest significant difference test. Polynomial contrasts tested the linear and quadratic effect of PP inclusion levels. Results revealed that PP inclusion, improved (P < 0.05) laying rate and egg mass, compared to CON. Increasing PP inclusion level enhanced laying rate and egg mass, linearly and quadratically and peaked at P1000 (P < 0.05). In the ovaries, the AhR pathway genes assessed were down-regulated (P < 0.05) mainly at P1000 and P750 treatments. In addition, PP related cytoprotective potential was demonstrated via beneficial changes seen for the majority of the Nrf2-pathway genes assessed with the P1000 displaying most significant differences from CON. Conclusively, new data highlighted beneficial cytoprotective effects of PP inclusion on layer ovaries and documented further layer performance, with the inclusion level of 1000 mg PP/kg diet being the most prominent.

Interacting Networks of the Hypothalamic-Pituitary-Ovarian Axis Regulate Layer Hens Performance

Egg production is a vital biological and economic trait for poultry breeding. The 'hypothalamic-pituitary-ovarian (HPO) axis' determines the egg production, which affects the layer hens industry income. At the organism level, the HPO axis is influenced by the factors related to metabolic and nutritional status, environment, and genetics, whereas at the cellular and molecular levels, the HPO axis is influenced by the factors related to endocrine and metabolic regulation, cytokines, key genes, signaling pathways, post-transcriptional processing, and epigenetic modifications. MiRNAs and lncRNAs play a critical role in follicle selection and development, atresia, and ovulation in layer hens; in particular, miRNA is known to affect the development and atresia of follicles by regulating apoptosis and autophagy of granulosa cells. The current review elaborates on the regulation of the HPO axis and its role in the laying performance of hens at the organism, cellular, and molecular levels. In addition, this review provides an overview of the interactive network regulation mechanism of the HPO axis in layer hens, as well as comprehensive knowledge for successfully utilizing their genetic resources.

Ligusticum chuanxiong promotes the angiogenesis of preovulatory follicles (F1-F3) in late-phase laying hens

Ligusticum chuanxiong (CX) is a traditional Chinese medicine that is widely planted throughout the world. CX is one of the most important and commonly used drugs to enhance blood circulation. The preovulatory follicles in laying hens have a large number of blood arteries and meridians that feed the follicles' growth and maturation with nutrients, hormones, and cytokines. With the extension of laying time, preovulatory follicles angiogenesis decreased gradually. In this study, we studied the mechanism of CX on preovulatory follicles angiogenesis in late-phase laying hens. The results show that CX extract can increase the angiogenesis of preovulatory follicles (F1-F3) of late-phase laying hens. CX extract can promote vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation in preovulatory follicles theca layers, promote the proliferation, invasion and migration through PI3K/AKT and RAS/ERK signaling pathways in primary follicle microvascular endothelial-like cells (FMECs). In addition, CX extract can up-regulate the expression of hypoxia inducible factor α (HIF1α) in granulosa cells (GCs) and granulosa layers through PI3K/AKT and RAS/ERK signaling pathways, thereby promoting the secretion of vascular endothelial growth factor A (VEGFA). In conclusion, the current study confirmed the promoting effect of CX extract on the preovulatory follicles angiogenesis, which sets the stage for the design of functional animal feed for late-phase laying hens.

Effect of Angelica Sinensis extract on the angiogenesis of preovulatory follicles (F1-F3) in late-phase laying hens

In order to form follicles and ovulate normally, there must be abundant blood vessels. Angelica sinensis (Oliv.) Diels (AS), as a traditional Chinese medicinal herb, has the effects of tonifying the blood and activating the blood circulation. However, the effect of AS on angiogenesis in hen-follicles remains to be discovered. In this study, we identified vascular richness, granulosa layer thickness, expression of platelet endothelial cell adhesion molecule-1 (CD31) and the content of vascular endothelial growth factor A (VEGFA) in granulosa layers to elucidate the effect of AS extract on angiogenesis in preovulatory follicles (F1-F3) of late-phase laying hens (75 wk). Based on network pharmacology, we predicted beta-sitosterol, ferulic acid, and caffeic acid as the main active components of AS, and hypoxia-inducible factor-1α (HIF1α), vascular endothelial growth factor receptor 2 (VEGFR2) as hub targets of AS in angiogenesis. The intersection targets were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and the hub targets were verified by immunofluorescence and western blot. Molecular docking of active components with hub targets was performed and verified in vitro. The results showed that AS extract promoted angiogenesis in preovulatory follicles and increased granulosa cell layer thickness, CD31 expression and content of VEGFA. Experiments in vitro and in vivo demonstrated that AS extract promoted the expression of HIF1α and VEGFA, up-regulated the phosphorylation levels of VEGFR2. These results further demonstrated the reliability of molecular docking and network pharmacology findings. In summary, AS extract can promote angiogenesis in the preovulatory follicles in late-phase laying hens.

SIRT6 regulates SREBP1c-induced glucolipid metabolism in liver and pancreas via the AMPKα-mTORC1 pathway

The aim of this study was to determine the mechanism by which SIRT6 regulates glucolipid metabolism disorders. We detected histological and molecular changes in Sprague-Dawley rats as well as in BRL 3A and INS-1 cell lines subjected to overnutrition and starvation. SIRT6, SREBP1c, and glucolipid metabolism biomarkers were identified by fluorescence co-localization, real-time PCR, and western blotting. Gene silencing studies were performed. Recombinant SIRT6, AMPK agonist (AICAR), mTOR inhibitor (rapamycin), and liver X receptor (LXR) agonist (T0901317) were used to pre-treated in BRL 3A and INS-1 cells. Real-time PCR and western blotting were used to detect related proteins, and cell counting was utilized to detect proliferation. We obtained conflicting results; SIRT6 and SREBP1c appeared in both the liver and pancreas of high-fat and hungry rats. Recombinant SIRT6 alleviated the decrease in AMPKα and increase in mTORC1 (complex of mTOR, Raptor, and Rheb) caused by overnutrition. SIRT6 siRNA reversed the glucolipid metabolic disorders caused by the AMPK agonist and mTOR inhibitor but not by the LXR agonist. Taken together, our results demonstrate that SIRT6 regulates glycolipid metabolism through AMPKα-mTORC1 regulating SREBP1c in the liver and pancreas induced by overnutrition and starvation, independent of LXR.

Promotion Effect of Angelica Sinensis Extract on Angiogenesis of Chicken Preovulatory Follicles in Vitro

Preovulatory follicles need a network of blood vessels to growth and maturation in hens (Gallus gallus). Angelica sinensis (Oliv.) (AS), a traditional Chinese herb, displays a novel pro-angiogenic activity. The molecular mechanisms underlying AS promoting preovulatory follicles angiogenesis are poorly understand. Several recent studies investigated the expression of vascular endothelial growth factor A (VEGF-A) in angiogenesis. In order to explore the promotion effect of AS extract on angiogenesis of chicken preovulatory follicles, we studied the effect of AS extract on follicle microvascular endothelial-like cells of chicken (FMEC) and granulosa cells (GC). The current study indicated that AS extract could promote the proliferation of FMECs and GCs. The assays of wounding healing, transwell invasion and tube formation showed that AS extract could enhance the invasion and migration ability of FMECs in vitro. The results of western blot and RT-PCR showed that AS extract promoted the phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2) in FMECs by activating the PI3K/AKT signaling pathway. The AS extract activated PI3K/AKT signaling pathway and up-regulated the expressions of hypoxia-inducible factor 1-α (HIF1-α) and VEGF-A in GCs. In addition, treatment of FMECs and GCs with LY294002 (a PI3K inhibitor) significantly down-regulated the phosphorylation of VEGFR2, VEGF-A, and HIF1-α. The mRNA expression levels of PI3K, AKT, VEGF-A, VEGFR2, and HIF1-α were consistent with protein expression levels. In conclusion, our research showed that AS extract can promote the follicle angiogenesis in hens in vitro, providing a basis for application of the traditional Chinese herb AS in poultry production.

MHY1485 enhances X-irradiation-induced apoptosis and senescence in tumor cells

The mammalian target of rapamycin (mTOR) is a sensor of nutrient status and plays an important role in cell growth and metabolism. Although inhibition of mTOR signaling promotes tumor cell death and several mTOR inhibitors have been used clinically, recent reports have shown that co-treatment with MHY1485, an mTOR activator, enhances the anti-cancer effects of anti-PD-1 antibody and 5-fluorouracil. However, it remains unclear whether MHY1485 treatment alters the effects of radiation on tumor cells. In this study, the radiosensitizing effects of MHY1485 were investigated using murine CT26 and LLC cell lines. We examined mTOR signaling, tumor cell growth, colony formation, apoptosis, senescence, oxidative stress, p21 accumulation and endoplasmic reticulum (ER) stress levels in cells treated with MHY1485 and radiation, either alone or together. We found that MHY1485 treatment inhibited growth and colony formation in both cell lines under irradiation and no-irradiation conditions, results that were not fully consistent with MHY1485's known role in activating mTOR signaling. Furthermore, we found that combined treatment with MHY1485 and radiation significantly increased apoptosis and senescence in tumor cells in association with oxidative stress, ER stress and p21 stabilization, compared to radiation treatment alone. Our results suggested that MHY1485 enhances the radiosensitivity of tumor cells by a mechanism that may differ from MHY1485's role in mTOR activation.