Alterations in rumen epithelial tight junctions (TJs) at the tissue and molecular levels during high-grain (HG) diet feeding are unknown. Here, 10 male goats were randomly assigned to either a hay diet (0% grain; n ϭ 5) or HG diet group (65% grain; n ϭ 5) to characterize the changes in ruminal epithelial structure and TJ protein expression and localization using scanning and transmission electron microscopy, quantitative real-time PCR, Western blot analysis, and immunofluorescence. After 7 wk of feeding, ruminal free LPS in HG group increased significantly (P Ͻ 0.001) compared with the hay group, and free LPS in the peripheral blood was detectable with concentrations of 0.8 Ϯ 0.20 EU/ml, while not detectable in the control, suggesting a leakage of LPS into the blood in the HG group. Correspondingly, the HG-fed goats showed profound alterations in ruminal epithelial structure and TJ proteins, depicted by marked epithelial cellular damage and intercellular junction erosion, down-regulation of TJ proteins claudin-4, occludin, and zonula occludens-1 mRNA and protein expression, as well as redistribution of claudin-1, claudin-4, and occludin. Furthermore, these changes in TJ proteins in the HG group were coupled with the upregulation of mRNA levels for the cytokines TNF-␣ and IFN-␥ in the ruminal epithelia. These results demonstrated for the first time that the HG diet feeding caused disruption of ruminal epithelial TJs that was associated with a local inflammatory response in the rumen epithelium. These findings may provide new insights into understanding the role of TJ proteins in the ruminal epithelial immune homeostasis of ruminants. rumen epithelium; high-grain diet; tight junction protein; lipopolysaccharide; inflammation IN CURRENT INTENSIVE RUMINANT production system, it has become common to use high-concentrate diets (high-grain, HG) to maximize energy intake and to improve milk production or daily weight gain, but highly fermentable diets can put the animal at risk. Rapidly fermentable nonstructural carbohydrates increase the rate of fermentation acid production in the rumen, and the accumulation of the acids leads to a decrease in ruminal pH, hyperosmolarity, and an increase in ruminal toxin concentration (2, 29). Previous studies have investigated the specific effect of low pH (9, 26), hyperosmolarity (20, 34), or an exposure to toxins (7) on ruminal epithelial barrier function in vitro. It should be acknowledged that any one or the combination of these factors may affect epithelial barrier function. In addition, the prominent histological alterations during HG feeding strongly suggest an impaired barrier function (35-37) that may provide the opportunity for the translocation of toxins and bacteria from the rumen into the blood, ultimately affecting animal health and productivity (28). Although there is fundamental knowledge about the consequences of HG feeding on ruminal epithelial barrier function, remarkably little information is currently available about the underlying molecular changes in ruminal epi...

High-grain (HG) feeding used in intensive goat production can affect the physiology of the rumen wall, but the changes induced in the epimural bacterial community and host Toll-like receptors (TLRs) are not well understood. In this study, 10 male goats were randomly allocated to two groups and fed either a hay diet (0% grain; n = 5) or an HG diet (65% grain; n = 5). The changes in the ruminal epithelial bacterial community and expression of TLRs during long-term (7 weeks) HG feeding were determined using pyrosequencing and quantitative real-time polymerase chain reaction. Principal coordinate analysis and analysis of molecular variance (AMOVA) results showed that HG feeding caused a strong shift in bacterial composition and structure. At the genus level, our data revealed that it increased the relative abundance of taxa Butyrivibrio, unclassified Clostridiales, Mogibacterium, unclassified Anaerolineaceae, and Succiniclasticum, and decreased the proportion of unclassified Ruminococcaceae, unclassified Rikenellaceae, unclassified Erysipelotrichaceae, Howardella, and unclassified Neisseriaceae. The HG-fed goats also exhibited upregulation of the relative mRNA expression of TLR2, TLR3, and TLR5 in the rumen epithelium (P < 0.05). Correlation analysis revealed that the increase in TLR expression was associated with changes in the relative abundance of ruminal epithelial bacteria. This study provides a first insight into the adaptive response of ruminal epithelial bacterial populations to HG feeding in goats and shows that these changes were associated with alterations in TLR expression. These findings provide new insight into understanding of host–microbial relationships in ruminants.

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Volatile compounds in the three Longjing tea were analyzed by gas chromatography-mass spectrometry with method of solid phase microextraction-gas chromatography. Furthermore, aroma-active compounds of three Longjing tea were analyzed by gas chromatography-olfactometry and odor activity value. However, the kinds of aroma-active compounds identified from those two methods were different. The results showed that dihydroactinidiolide (aroma intensity = 9.1-9.2), (Z)-nerolidol (aroma intensity = 8.4-8.8), benzyl alcohol (aroma intensity = 8.1-8.4), and epoxylinalool (aroma intensity = 8.1-8.5) presented the highest aroma intensity in three green tea samples. While geraniol (422.4-2508.3), epoxylinalool (601.5-1033.9), (Z)-nerolidol (235.5-559.3), 2-ethyl-3,5-dimethylpyrazine (328.0-420.6), β-ionone (227.7-387.3) presented higher odor activity values than other compounds. Thus, this study uses recombination aroma models to identify selected important aroma-active compounds from gas chromatography-olfactometry and odor activity value and verifies their effectiveness to identify the aroma profile characterization of three Longjing tea samples using electronic nose analysis and sensory evaluation. The radar plot of electronic nose analysis tallied with sensory evaluation indicated that the odor activity value-based aroma models were more similar to the original Longjing tea aroma than gas chromatography-olfactometry-based models.

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Classical major histocompatibility complex (MHC) class I, first identified in the immune system, is also expressed in the developing and adult central nervous system (CNS). Although the MHC class I molecules have been found to be expressed in the CNS of different species, a necessary step to elucidate the temporal and spatial expression patterns of MHC class I molecules in the brain development has never been taken. Frozen sections were made from the brains of embryonic and postnatal C57BL/6 J mice, and the expression of H-2D(b) mRNA was examined by in situ hybridization. Immunofluorescence was also performed to define the cell types that express H2-D(b) in P15 mice. At E10.5, the earliest stage we examined, H2-D(b) was expressed in neuroepithelium of the brain vesicles. From E12.5 to P0, H2-D(b) expression was mainly located at cerebral cortex, neuroepithelium of the lateral ventricle, neuroepithelium of aquaeductus and developing cerebellum. From P4 to adult, H2-D(b) mRNA was detected at olfactory bulb, hippocampus, cerebellum and some nerve nuclei. The major cell types expressing H-2D(b) in P15 hippocampus, cerebral cortex and olfactory bulb were neuron. H2-K(b) signal paralleled that of H2-D(b) and the expression levels of the two molecules were comparable throughout the brain. The investigation of the expression pattern of H-2D(b) at both embryonic and postnatal stages is important for further understanding the physiological and pathological roles of H2-D(b) in the developing CNS.

Sodium bicarbonate supplementation has beneficial effects in the reduction of bioamine levels and the increase in ruminal pH, and in modifying the microbial ecology of the rumen; however, it results in an accumulation of LPS under high-grain diet conditions. © 2016 Society of Chemical Industry.