Cloning, Phylogenetic Analysis, and Distribution of Free Fatty Acid Receptor GPR120 Expression along the Gastrointestinal Tract of Housing versus Grazing Kid Goats

The ileal microbiome and mucosal immune profiles in response to dietary supplementation of ultra-grinded Astragalus membranaceus in weaned goats

Weaning goats are susceptible to diarrhea and have weakened immune functions due to physiological, dietary and environmental stresses. Astragalus membranaceus (A. membranaceus), a traditional Chinese medicinal herb, has been shown to improve growth performance and immunity in weaned ruminants. However, the influence mechanism of A. membranaceus on intestinal microbiota and mucosal immunity in weaned goats is still unknown. This study investigated the effects of ultra-grinded A. membranaceus (UGAM) on the immune function and microbial community in the ileum of weaned goats. Eighteen healthy weaned Xiangdong black goats (BW, 5.30 ± 1.388 kg) were used in a study of completely randomized block design with 28 days long. The animals were randomly assigned to either a basal diet supplemented with 10 g/d of milk replacer (CON, n = 9) or the CON diet supplemented with 10 g/head UGAM (UGAM, n = 9). Supplementation of UGAM increased (p < 0.05) the plasma concentrations of total protein and albumin. Meanwhile, the addition of UGAM reduced (p < 0.05) the relative mRNA expression of the IL-6 gene (a marker of inflammation), indicating the potential immunomodulatory effect of UGAM. Moreover, the relative abundances of Verrucomicrobiota and Mycoplasma were lower (p < 0.05) in the ileum of goats supplemented with UGAM than CON. These findings suggest that dietary supplementation of UGAM may have enhanced the ileum health of weaned goats by reducing inflammation factor expression and reducing the relative abundance of pathogenic microbes. The observed beneficial effects of ultra-grinded A. membranaceus on ileal mucosal immune and the community of ileal microbiota indicate its potential to be used as a viable option for promoting the well-being of weaned goats under weaning stress.

Effect of alfalfa substituted with ramie on the expression of apoptotic genes in the gastrointestinal tracts of goats

The study investigated the effect of alfalfa hay substituted with ramie silage on the expression of apoptotic genes in the gastrointestinal tract of goats. Thirty‐two goats were randomly allocated into four groups, in which the alfalfa was substituted with ramie at 0%, 35%, 75%, and 100% levels, respectively. In the rumen, the mRNA expression of Bax was significantly up‐regulated (p = .0007) when alfalfa was 100% substituted by ramie; the mRNA expression of Bcl‐2/Bax was significantly down‐regulated (p = .02) when alfalfa was 100% substituted by ramie compared with the 75% substituted treatment; the protein expression of Bcl‐xl was significantly down‐regulated (p = .03) when alfalfa was 100% substituted by ramie compared with 35% and 75% substituted treatments, respectively. In the jejunum, the mRNA expression of p53 was significantly up‐regulated (p = .01) when alfalfa was 100% substituted by ramie compared with 0% and 35% substituted treatments; the protein expression of p53 was significantly up‐regulated (p = .001) when alfalfa was 35% substituted by ramie compared with 0% and 75% substituted treatments. However, the activity of Caspase‐3 was not affected by different substituting levels of ramie in the rumen and jejunum of goats (p > .05). In conclusion, ramie with high substitution had strong antinutritional effect, which might promote the apoptosis in the gastrointestinal tract of goats in a caspase‐independent manner, thus affecting the growth and development of goat. It was suggested that ramie should not replace alfalfa more than 35% in the process of goat feeding.

The expression of nutrient chemosensing gate molecules in the ileum and colon is altered for goats fed on a high-grain diet

Limited knowledge is clarified about alterations in the related expression of nutrient chemosensors in the distal small intestine and hindgut under a high-grain (HG) diet in small ruminants. Herein, this study was performed to investigate the expression changes related to nutrient sensing and transport in the ileal and colonic epithelium of goats in response to feeding an HG diet. Twelve Liuyang black goats (similar age and weight) were randomly assigned into two groups: an HG diet (concentrate: hay = 90:10) and a CON diet (concentrate: hay = 55:45). Immunohistochemistry was applied to detect morphological changes in the gut epithelium together with altered expression of chemosensors in the ileum and colon. The results showed that feeding an HG diet increased ileal villus height and depth and induced mucosal sloughing in the colon. The expressions of the nutrient transporters GLUT2, GLUT5, SGLT2, CD36, rBAT, EAAT3, and LAT2 and sensing receptors GPR43 and T1R1 were promoted in the ileum under HG conditions. Moreover, feeding an HG diet also enhanced the expression of GLUT2, SGLT2, CD36, and GPR43 in the colon. These findings indicate that adaptation of the gastrointestinal tract to the HG diet promoted the absorption of glucose, fatty acids, and amino acids in goats.

Multi-Omics Analysis of Mammary Metabolic Changes in Dairy Cows Exposed to Hypoxia

Hypoxia exposure can cause a series of physiological and biochemical reactions in the organism and cells. Our previous studies found the milk fat rate increased significantly in hypoxic dairy cows, however, its specific metabolic mechanism is unclear. In this experiment, we explored and verified the mechanism of hypoxia adaptation based on the apparent and omics results of animal experiments and in vitro cell model. The results revealed that hypoxia exposure was associated with the elevation of AGPAT2-mediated glycerophospholipid metabolism. These intracellular metabolic disorders consequently led to the lipid disorders associated with apoptosis. Our findings update the existing understanding of increased adaptability of dairy cows exposure to hypoxia at the metabolic level.

Cloning, phylogenetic analysis, and postnatal expression of oligopeptide transporter PepT1 in gastrointestinal tract of kid goats receiving supplemental feed or pasture

This study aimed to clone the cDNA of PepT1, an H+-dependent oligopeptide transporter, from kid goats and examine effects of physiological development (suckling, weaning, and post-weaning) of the animal and feeding system (supplemental feeding vs. grazing) on peptide transport capability. A 2395 bp cDNA sequence of pept1 (GenBank: MH308024) was cloned and phylogenetic analysis revealed a high homology and structure similarity with PepT1 of sheep and cattle. The pept1 was expressed throughout the gastrointestinal tract of kid goats immediately after birth and during development. Relative abundance of pept1 decreased in all segments except the middle-jejunum during suckling, whereas its expression in most segments of small intestine increased with age after weaning and remained stable thereafter. Middle-jejunum was the predominant expression site and probably the main peptide absorption site. Supplemental feeding enhanced pept1 expression because it increased protein intake compared with grazing. No feeding system × age interaction was observed in most segments; the expression was age related during suckling and diet related during weaning and post-weaning, indicating that feeding system and age had independent effects on pept1 expression. These results indicate that PepT1 plays an important role for protein nutrition in neonatal goats, and its expression can be affected by feeding system.

Comparison of the Effects of Nonprotein and Protein Nitrogen on Apoptosis and Autophagy of Rumen Epithelial Cells in Goats

Simple Summary

Proteins provide important raw materials for the self-renewal of cells in the gastrointestinal tract. Cell self-renewal is inseparable from the coordination between apoptosis and autophagy. Previous researchers have explored whether different nitrogen sources are linked to activation or inhibition of apoptosis/autophagy. However, information on the regulatory mechanism of apoptosis and autophagy induced by different nitrogen sources among cells in the gastrointestinal tract is limited. This study attempted to compare the effects of different nitrogen sources on apoptosis and autophagy of rumen epithelial cells in goats through molecular biology techniques such as flow cytometry, transmission electron microscopy, and fluorescence microscopy. On the basis of the obtained results, we found that autophagy had a less obvious ameliorative effect on ruminal epithelial cell apoptosis after treatment with protein nitrogen than after treatment with nonprotein nitrogen.

Abstract

Protein nutrition is particularly important for the self-renewal processes of gastrointestinal epithelial cells. The self-renewal of cells is inseparable from the interaction between apoptosis and autophagy. However, there are few reports on the relationship between different nitrogen sources and apoptosis/autophagy. In this study, the relative protein expression of Bcl-2-associated X protein(Bax), caspase-3, and p62 was significantly higher (p < 0.05), while that of Bcl-xl, Bcl-2, Beclin1, and Microtuble-associated protein light chain 3 (LC3-II) was significantly lower (p < 0.05), in the NH₄Cl group in comparison with the NH₄Cl + 4-phenylbutyric acid (4PBA) group. In addition, the relative protein expression of Bax and caspase-3 was significantly higher (p < 0.05), while that of Bcl-2 and Bcl-xl was decreased significantly (p < 0.05), in the NH₄Cl + 3-Methyladenine (3-MA) group and the methionine (Met) + 3-MA group in comparison with the NH₄Cl group. Furthermore, the relative protein expression of Beclin1 and LC3B-II was significantly lower (p < 0.05), while that of p62 was significantly higher (p < 0.05), in the NH₄Cl + Z-VAD-FMK group and the Met + Z-VAD-FMK group in comparison with the NH₄Cl group. In conclusion, our results suggested that endoplasmic reticulum (ER) stress played a critical role in the crosstalk between apoptosis and autophagy induced by NH₄Cl and Met. Autophagy had a more obvious ameliorative effect on ruminal epithelial cell apoptosis after treatment with nonprotein nitrogen than after treatment with protein nitrogen. These findings may reveal the molecular mechanism of apoptosis and autophagy induced by nonprotein nitrogen and protein nitrogen.

Characterization of Free Fatty Acid Receptor 4 and Its Involvement in Nutritional Control and Immune Response in Pacific Oysters (Crassostrea gigas)

Free fatty acid receptor 4 (FFAR4) has various physiological functions, including energy regulation and immunological homeostasis. We examined the only FFAR4 homologue in the Pacific oyster Crassostrea gigas (CgFFAR4), which functions as a sensor of long-chain fatty acids. CgFFAR4 is 1098 bp long and contains a seven-transmembrane G protein-coupled receptor domain. CgFFAR4 expression was high in the hepatopancreas, but it was downregulated after fasting, indicating that it plays an essential role in food digestion. Lipopolysaccharide stimulation downregulated CgFFAR4 level, probably as an immune response of the animal. Reduced glycogen level alongside decreased insulin receptor, insulin receptor substrate, and C. gigas glycogen synthase transcription levels after CgFFAR4 knockdown revealed that CgFFAR4 was involved in the regulation of fatty acid and glycogen levels via the insulin pathway. Accordingly, this is the first study on an invertebrate FFAR and provides new insights into the role of this receptor in immune response and nutritional control.

LPAR5, GNAT3 and partial amino acid transporters messenger RNA expression patterns in digestive tracts, metabolic organs and muscle tissues of growing goats

Sufficient amino acid (AA) transport is essential to ensure the normal physiological function and growth of growing animals. The processes of AA sensing and transport in humans and murine animals, but rarely in goats, have been arousing great interest recently. This study was conducted to investigate the messenger RNA expression patterns of lysophosphatidic acid receptor 5 (LPAR5), guanine nucleotide-binding protein α-transducing 3 (GNAT3) and important partial AA transporters in digestive tracts, metabolic organs and muscles of growing goats. The results showed that these genes were widely expressed in goats, and had different expression patterns. LPAR5, GNAT3, solute carrier (SLC38A2), SLC7A7, SLC7A1 and SLC3A1 were rarely expressed in the rumen, but were highly expressed in the abomasum and intestine which are the main sites of AA absorption. GNAT3, SLC38A1, SLC38A2, SLC6A19, SLC7A7 and SLC7A1 showed comparatively high expression in the pancreas and the vital digestive glands, and the relatively high expression of these nine genes were noted in the tibialis posterior, the active muscle in energy metabolism. The correlation analysis showed that there were certain positive correlation among most genes. The current results indicate that the AA sensing and transport occur extensively in the abomasum and small intestine, metabolic organs and muscle tissues of ruminants, and that related genes have tissue specificity.

Inferring the Skeletal Muscle Developmental Changes of Grazing and Barn-Fed Goats from Gene Expression Data

Thirty-six Xiangdong black goats were used to investigate age-related mRNA and protein expression levels of some genes related to skeletal muscle structural proteins, MRFs and MEF2 family, and skeletal muscle fiber type and composition during skeletal muscle growth under grazing (G) and barn-fed (BF) feeding systems. Goats were slaughtered at six time points selected to reflect developmental changes of skeletal muscle during nonrumination (days 0, 7, and 14), transition (day 42), and rumination phases (days 56 and 70). It was observed that the number of type IIx in the longissimus dorsi was increased quickly while numbers of type IIa and IIb decreased slightly, indicating that these genes were coordinated during the rapid growth and development stages of skeletal muscle. No gene expression was affected (P > 0.05) by feeding system except Myf5 and Myf6. Protein expressions of MYOZ3 and MEF2C were affected (P < 0.05) by age, whereas PGC-1α was linearly decreased in the G group, and only MYOZ3 protein was affected (P < 0.001) by feeding system. Moreover, it was found that PGC-1α and MEF2C proteins may interact with each other in promoting muscle growth. The current results indicate that (1) skeletal muscle growth during days 0-70 after birth is mainly myofiber hypertrophy and differentiation, (2) weaning affects the expression of relevant genes of skeletal muscle structural proteins, skeletal muscle growth, and skeletal muscle fiber type and composition, and (3) nutrition or feeding regimen mainly influences the expression of skeletal muscle growth genes.