Abundantly expressed hepatic genes and their differential expression in liver of prelaying and laying geese

Comparative liver transcriptome analysis of duck reveals potential genes associated with egg production

BACKGROUND

Molecular studies on egg production in ducks were mostly focused on brain and ovaries as they are directly involved in egg production. Liver plays a vital role in cellular lipid metabolism. It also plays a decisive role in reproductive organ development, including yolk generation in laying ducks at sexual maturity. However, the precise molecular mechanism involved in the liver-blood-ovary axis in ducks remains elusive.

METHODS AND RESULTS

In this study, we analysed the liver transcriptome of laying (LA), immature (IM) and broody (BR) ducks using RNA sequencing to understand the role of genes expressed in the liver. The comparative transcriptome analysis revealed 82 DEGs between LA and IM ducks, 47 DEGs between LA and BR ducks and 51 DEGs between IM and BR ducks. GO analysis of DEGs, showed that DEGs were mainly involved in cellular anatomical entity, intracellular, metabolic process, and binding. Furthermore, pathway analysis indicated the important role of Wnt signaling pathway in egg formation and embryo development. Our study showed several candidate genes including vitellogenin-1, vitellogenin-2, riboflavin binding protein, G protein subunit gamma 4, and fatty acid binding protein 3 that are potentially related to egg production in ducks.

CONCLUSIONS

The study provides valuable information on the genes responsible for egg production and thus, pave the way for further investigation on the molecular mechanisms of egg production in duck.

Intestinal Mucosal Immunity-Mediated Modulation of the Gut Microbiome by Oral Delivery of Enterococcus faecium Against Salmonella Enteritidis Pathogenesis in a Laying Hen Model

Enterococcus faecium (E. faecium) is a protective role that has crucial beneficial functions on intestinal homeostasis. This study aimed to investigate the effects of E. faecium on the laying performance, egg quality, host metabolism, intestinal mucosal immunity, and gut microbiota of laying hens under the Salmonella Enteritidis (S. Enteritidis) challenge. A total of 400 45-week-old laying hens were randomly divided into four treatments (CON, EF, SCON, and SEF groups) with five replicates for each group and 20 hens per replicate and fed with a basal diet or a basal diet supplemented with E. faecium (2.5 × 10⁸ cfu/g feed). The experiment comprised two phases, consisting of the pre-salmonella challenged phase (from day 14 to day 21) and the post-salmonella challenged phase (from day 21 to day 42). At day 21 and day 22, the hens in SCON and SEF groups were orally challenged with 1.0 ml suspension of 10⁹ cfu/ml S. Enteritidis (CVCC3377) daily, whereas the hens in CON and EF groups received the same volume of sterile PBS. Herein, our results showed that E. faecium administration significantly improved egg production and shell thickness during salmonella infection. Also, E. faecium affected host lipid metabolism parameters via downregulating the concentration of serum triglycerides, inhibited oxidative stress, and enhanced immune functions by downregulating the level of serum malondialdehyde and upregulating the level of serum immunoglobulin G. Of note, E. faecium supplementation dramatically alleviated intestinal villi structure injury and crypt atrophy, and improved intestinal mucosal barrier injuries caused by S. Enteritidis challenge. Moreover, our data revealed that E. faecium supplementation ameliorated S. Enteritidis infection-induced gut microbial dysbiosis by altering the gut microbial composition (reducing Bacteroides, Desulfovibrio, Synergistes, and Sutterella, and increasing Barnesiella, Butyricimonas, Bilophila, and Candidatus_Soleaferrea), and modulating the gut microbial function, such as cysteine and methionine metabolism, pyruvate metabolism, fatty acid metabolism, tryptophan metabolism, salmonella infection, and the PI3K-Akt signaling pathway. Taken together, E. faecium has a strong capacity to inhibit the S. Enteritidis colonization of hens. The results highlight the potential of E. faecium supplementation as a dietary supplement to combat S. Enteritidis infection in animal production and to promote food safety.

Monitoring aging of hen egg by integrated quantitative peptidomic procedures

Environmental conditions and timing of egg storage highly affect raw material quality. Aging and endogenous processing of constituent proteins can determine important changes in specific functions and technological properties of inner egg compartments. We here used integrated peptidomic procedures to identify peptide markers of egg freshness. At first, peptides extracted from egg white and yolk plasma taken from eggs stored for different times were subjected to a label-free untargeted quantitation procedure based on nanoLC-ESI-Q-Orbitrap-MS/MS, which identified 836 and 1974 unique variable molecules, respectively. By applying stringent criteria for filtering data, 30 and 66 putative egg aging markers were selected for egg white and yolk plasma, respectively. Proposed molecules were then validated through a targeted label-free parallel reaction monitoring procedure based on nanoLC-ESI-Q-Orbitrap-MS/MS, confirming quantitative trends for 19 and 25 peptides in egg white and yolk plasma, respectively, and generating a robust panel of egg storage markers. Quantitative results reflected physico-chemical phenomena occurring in egg compartments during storage and offered essential information for the development of novel control procedures to assess quality features of fresh/stored raw material.

Green Tea Powder Decreased Egg Weight Through Increased Liver Lipoprotein Lipase and Decreased Plasma Total Cholesterol in an Indigenous Chicken Breed

Simple Summary

Tons of green tea powder (GTP) are produced and cast off during green tea processing. It is suggested that GTP could increase immunity and health, and so improve animal production performance. We demonstrated that one percent of GTP supplemented in the diet did not affect egg production. However, long time GTP inclusion resulted in decreased egg weight and increased feed-to-egg ratio. Combined with plasma lipid concentration, the decreased egg weight might be because of lower plasma lipid concentration, increased plasma orexin A, and liver lipoprotein lipase expression in chickens fed a diet containing GTP.

Abstract

Whether or not green tea promotes egg production is unclear. Huainan partridge chickens at 20 weeks of age were divided into two groups, with one group fed a basal diet (control) and one fed a basal diet plus 10 g/kg green tea powder (GTP) for 12 weeks. Egg production (EP) and feed intake (FI) were recorded daily. Plasma lipid parameters, and apolipoprotein-B (Apo-B), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), and lipoprotein lipase (LPL) expression were determined every four weeks. Egg production and FI showed no significant difference between the two groups (p > 0.05). Egg weight was 47.58 g in the control group, which was higher than that of the GTP group, and the feed-to-egg ratio (FCR) was 4.62 in the control group, which was lower than that of the GTP group after 12 weeks feeding. Compared with the control group, plasma orexin A (p < 0.05), high-density lipoprotein (HDL), apolipoprotein A (Apo A), and very high-density lipoprotein (VHDL) (p < 0.01, respectively) were increased. Plasma glucose (Glu), free fatty acid (FFA), apolipoprotein B (Apo B), triglyceride (TG), total cholesterol (TC) (p < 0.01, respectively), and low density lipoprotein (LDL) (p < 0.05) were decreased in the GTP group after 8 weeks feeding. The LPL expression in the liver was increased in the GTP group after 8 to 12 weeks feeding when compared to the control group (p < 0.05). Chickens fed GTP did not affect EP, but decreased egg weight, which might be because of lower plasma lipid concentration, increased plasma Orexin A, and liver LPL expression.

Protein Deimination and Extracellular Vesicle Profiles in Antarctic Seabirds

Pelagic seabirds are amongst the most threatened of all avian groups. They face a range of immunological challenges which seem destined to increase due to environmental changes in their breeding and foraging habitats, affecting prey resources and exposure to pollution and pathogens. Therefore, the identification of biomarkers for the assessment of their health status is of considerable importance. Peptidylarginine deiminases (PADs) post-translationally convert arginine into citrulline in target proteins in an irreversible manner. PAD-mediated deimination can cause structural and functional changes in target proteins, allowing for protein moonlighting in physiological and pathophysiological processes. PADs furthermore contribute to the release of extracellular vesicles (EVs), which play important roles in cellular communication. In the present study, post-translationally deiminated protein and EV profiles of plasma were assessed in eight seabird species from the Antarctic, representing two avian orders: Procellariiformes (albatrosses and petrels) and Charadriiformes (waders, auks, gulls and skuas). We report some differences between the species assessed, with the narrowest EV profiles of 50-200 nm in the northern giant petrel Macronectes halli, and the highest abundance of larger 250-500 nm EVs in the brown skua Stercorarius antarcticus. The seabird EVs were positive for phylogenetically conserved EV markers and showed characteristic EV morphology. Post-translational deimination was identified in a range of key plasma proteins critical for immune response and metabolic pathways in three of the bird species under study; the wandering albatross Diomedea exulans, south polar skua Stercorarius maccormicki and northern giant petrel. Some differences in Gene Ontology (GO) biological and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for deiminated proteins were observed between these three species. This indicates that target proteins for deimination may differ, potentially contributing to a range of physiological functions relating to metabolism and immune response, as well as to key defence mechanisms. PAD protein homologues were identified in the seabird plasma by Western blotting via cross-reaction with human PAD antibodies, at an expected 75 kDa size. This is the first study to profile EVs and to identify deiminated proteins as putative novel plasma biomarkers in Antarctic seabirds. These biomarkers may be further refined to become useful indicators of physiological and immunological status in seabirds-many of which are globally threatened.

Transcriptome analysis of follicles reveals the importance of autophagy and hormones in regulating broodiness of Zhedong white goose

Broodiness, a maternal behavior and instinct for natural breeding in poultry, inhibits egg production and affects the poultry industry. Phenotypic and physiological factors influencing broodiness in poultry have been extensively studied, but the molecular regulation mechanism of broodiness remains unclear. Effective research strategies focusing on broodiness are hindered by limited understanding of goose developmental biology. Here we established the transcriptomes of goose follicles at egg-laying and broody stages by Illumina HiSeq platform and compared the sequenced transcriptomes of three types of follicles (small white, large white and small yellow). It was found that there were 92 up-regulated and 84 down-regulated transcription factors and 101 up-regulated and 51 down-regulated hormone-related genes. Many of these genes code for proteins involved in hormone response, follicular development, autophagy, and oxidation. Moreover, the contents of progesterone and estradiol in follicles were altered, and the autophagy levels of follicles were enhanced during the broody stage. These results suggest that hormone- and autophagy-signaling pathways are critical for controlling broodiness in the goose. We demonstrated that transcriptome analysis of egg-laying and broody Zhedong white goose follicles provided novel insights into broodiness in birds.

Transcriptome Analysis and Identification of Differentially Expressed Transcripts of Immune-Related Genes in Spleen of Gosling and Adult Goose

The goose (Anser cygnoides), having high nutritional value, high-quality feathers and high economic benefit, is an economically important poultry species. However, the molecular mechanisms underlying the higher susceptibility to pathogens in goslings than in adult geese remains poorly understood. In this study, the histological sections of spleen tissue from a two-week-old gosling and an adult goose, respectively, were subjected to comparative analysis. The spleen of gosling was mainly composed of mesenchyma, accompanied by scattered lymphocytes, whereas the spleen parenchyma was well developed in the adult goose. To investigate goose immune-related genes, we performed deep transcriptome and gene expression analyses of the spleen samples using paired-end sequencing technology (Illumina). In total, 50,390 unigenes were assembled using Trinity software and TGICL software. Moreover, these assembled unigenes were annotated with gene descriptions and gene ontology (GO) analysis was performed. Through Kyoto encyclopedia of genes and genomes (KEGG) analysis, we investigated 558 important immune-relevant unigenes and 23 predicted cytokines. In addition, 22 immune-related genes with differential expression between gosling and adult goose were identified, among which the three genes showing largest differences in expression were immunoglobulin alpha heavy chain (IgH), mannan-binding lectin serine protease 1 isoform X1 (MASP1) and C–X–C chemokine receptor type 4 (CXCR4). Finally, of these 22 differentially expressed immune-related genes, seven genes, including tumor necrosis factor receptor superfamily member 13B (TNFRSF13B), C-C motif chemokine 4-like (CCL4), CXCR4, interleukin 2 receptor alpha (IL2RA), MHC class I heavy chain (MHCIα), transporter of antigen processing 2 (TAP2) IgH, were confirmed by quantitative real-time PCR (qRT-PCR). The expression levels of all the candidate unigenes were up-regulated in adult geese other than that of TNFRSF13B. The comparative analysis of the spleen transcriptomes of gosling and adult goose may promote better understanding of immune molecular development in goose.

Antimicrobial potential of egg yolk ovoinhibitor, a multidomain Kazal-like inhibitor of chicken egg

Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis . The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs).