Comparative iTRAQ Proteomics Reveals Multiple Effects of Selenium Yeast on Dairy Cows in Parturition.

The effects of prepartum dietary supplementation with selenium yeast on low abundant plasma proteins in postpartum dairy cows are not known. In this study, 24 healthy parturient dairy cows were divided into two groups (group C, a control group, and group T, a selenium treatment group). Low abundance proteins were extracted from plasma samples of calving cows, and 542 proteins were identified by isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis. Dietary supplementation with selenium yeast caused differential abundance of 48 proteins with a fold change of more than 1.2 or less than 0.83 (p < 0.05); 14 proteins were upregulated and 34 were downregulated. The top five gene ontology (GO) enrichment terms for the differentially expressed proteins were protein homotetramerization (or tetramerization), defense response to bacteria or fungus, acute-phase reactions, nucleotide catabolic process, and positive regulation of lipid metabolic process. All proteins involved in acute-phase reactions were downregulated, indicating that selenium ameliorates systemic inflammation. The vast majority of proteins involved in the defense response to microorganisms were downregulated, thereby affecting innate immunity. The decreased abundance of apolipoprotein A-I and apolipoprotein C-II, critical proteins for positive regulation of lipid metabolism, indicated that selenium may optimize lipid metabolism. The iTRAQ results showed that prenatal supplementation with yeast selenium can relieve systemic inflammation after parturition. Moreover, selenium may reduce the effects of metabolic diseases, which can improve glyconeogenesis and prevent ketosis and fatty liver.

Responses in ileal and cecal bacteria to low and high amylose/amylopectin ratio diets in growing pigs.

Dietary starch that escapes digestion in the small intestine may serve as a carbon source for bacterial fermentation in the distal intestine. This study aimed to compare the bacterial community in the ileal and cecal digesta of growing pigs fed diets with low (0.14, LR pigs) and high (0.43, HR pigs) amylose/amylopectin ratio. Pyrosequencing based on MiSeq 2000 platform showed that in ileum digesta, Bacteroidetes of LR pigs was markedly higher than that in HR pigs (P < 0.05). Megasphaera and Prevotella were the two most predominant genera in LR pigs, and Prevotella was significantly higher in LR pigs than in HR pigs (P < 0.05). Prevotella was predominant in cecal samples from both LR and HR pigs, although no significant differences were found between the two groups. In the ileum, Megasphaera elsdenii and Mitsuokella multacida were significantly (P < 0.01) higher in LR pigs along with an increase of acetate and butyrate concentrations. Halomonas pacifica, Escherichia fergusonii, and Actinobacillus minor which belong to class Gammaproteobacteria were significantly lower (P < 0.01) in HR pigs with a significant increase (P < 0.01) of Lactobacillus acetotolerans-like bacteria. Therefore, the changed bacterial community may lead to a transformation of microbial function, such as the alteration of fermentation mode which is showed on the change of microbial metabolites like the concentration of short-chain fatty acids (SCFAs), to a response to the switch of dietary composition, and in turn, to help host absorb and utilize nutrients efficiently. The increase of dietary amylose induced the reduction of conditioned pathogens which may probably be due to the increase of some probiotics such as Lactobacillus, thus reducing the risk of intestinal disease.

Responses in gut microbiota and fat metabolism to a halogenated methane analogue in Sprague Dawley rats.

Recent studies on germ-free mice show that intestinal methanogens may be closely associated with host's adipose metabolism. The present study aimed to investigate effects of inhibition of intestinal methanogen populations on host fat metabolism by establishing a healthy Sprague Dawley (SD) rat model through the intragastric administration of bromochlordomethane (BCM). Forty-five 8-week old healthy male SD rats were randomly divided into five groups including one control and four BCM treatments. The experiment lasted 60 days with two separate 30-day experimental periods. At the end of first period, three BCM treatment groups were further used: one group continued with BCM treatment, one group stopped with BCM treatment, and the other one inoculated with faecal mixture of methanogens from rats. Results showed that the methanogen population in feces was reduced sixfold with no effect on the bacterial community by daily dosing with BCM. Daily gain, epididymal fat pad weight, levels of plasma low-density lipoprotein and cholesterol were significantly higher in the BCM-treated animals, while the high-density lipoprotein was lower than that of the control. The expression of PPARγ, LPL, PP2A, SREBP-1c, ChREBP, FASN and adiponectin genes in BCM treatment group was universally upregulated, while the expression of Fiaf gene was downregulated. After termination of BCM treatment and followed either with or without re-inocubation with faecal methanogen mixture, the rats had their faecal methanogen populations, blood parameters and gene expression returned to the original level. Results suggest that regulation of gut methanogens might be a possible approach to control host body weight.

Diversity of methanogens in the hindgut of captive white rhinoceroses, Ceratotherium simum.

BACKGROUND: The white rhinoceros is on the verge of extinction with less than 20,200 animals remaining in the wild. In order to better protect these endangered animals, it is necessary to better understand their digestive physiology and nutritional requirements. The gut microbiota is nutritionally important for herbivorous animals. However, little is known about the microbial diversity in the gastrointestinal tract (GIT) of the white rhinoceros. Methanogen diversity in the GIT may be host species-specific and, or, function-dependent. To assess methanogen diversity in the hindgut of white rhinoceroses, an archaeal 16S rRNA gene clone library was constructed from pooled PCR products obtained from the feces of seven adult animals. RESULTS: Sequence analysis of 153 archaeal 16S rRNA sequences revealed 47 unique phylotypes, which were assigned to seven operational taxonomic units (OTUs 1 to 7). Sequences assigned to OTU-7 (64 out of 153 total sequencs - 42%) and OTU-5 (18%, 27/153) had 96.2% and 95.5% identity to Methanocorpusculum labreanum, respectively, making Methanocorpusculum labreanum the predominant phylotype in these white rhynoceroses. Sequences belonging to OTU-6 (27%, 42/153) were related (97.6%) to Methanobrevibacter smithii. Only 4% of the total sequences (6/153) were assigned to Methanosphaera stadtmanae (OTU-1). Sequences belonging to OTU-2 (4%, 6/153), OTU-3 (3%, 5/153) and OTU-4 (2%, 3/153) were distantly related (87.5 to 88,4%) to Methanomassiliicoccus luminyensis and were considered to be novel species or strains that have yet-to-be cultivated and characterized. CONCLUSION: Phylogenetic analysis indicated that the methanogen species in the hindgut of white rhinoceroses were more similar to those in the hindgut of horses. Our findings may help develop studies on improving the digestibility of forage for sustainable management and better health of these endangered animals.

Broilers fed dietary vitamins harbor higher diversity of cecal bacteria and higher ratio of Clostridium, Faecalibacterium, and Lactobacillus than broilers with no dietary vitamins revealed by 16S rRNA gene clone libraries.

Research on the interaction between dietary vitamins and intestinal bacteria is poorly understood. To investigate the effect of dietary vitamins on the cecal bacterial communities, 2 bacterial 16S rRNA gene clone libraries were constructed from pooled PCR products obtained from the cecal digesta of 28-d broilers fed diets with vitamins (V) at the NRC level or with no vitamins (NV). The results showed that BW gain and average feed intake of V broilers was significantly higher (P < 0.01) than NV broilers, whereas the feed/gain ratio was significantly lower (P < 0.01) in V broilers. A total of 188 and 185 clones were sequenced for the NV and V broilers, respectively. Sequence identity criterion of 98% was used to assign sequences to operational taxonomic units (OTU). Clones from the NV group broilers were assigned to 14 OTU, with 33% clones affiliated with the genus Clostridium, 19% affiliated with the genera Escherichia/Shigella, 14% affiliated with the genus Bacteroides, and the remaining clones (34%) affiliated with 5 other bacterial genera (Faecalibacterium, Parasporobacterium, Ruminococcus, Streptococcus, and Subdoligranulum). Clones from the V group broilers were assigned to 23 OTU, with 46% of the clones affiliated with the genus Clostridium, 11% affiliated with the genus Fecalibacterium, and the remaining clones (43%) affiliated with 8 other genera (Anaerofilum, Lactobacillus, Anaerotruncus, Oscillibacter, Alistipes, Gracilibacter, Acetivibrio, and Haloplasma). Three OTU assigned to Clostridium, Faecalibacterium, and Ruminoccus were shared between the 2 libraries. Shannon diversity index showed the V broilers exhibited significantly higher bacterial diversity (P = 0.05), and Libshuff analysis indicated that the community structure between the 2 groups was significantly different (P < 0.0001). These results suggest that lack of dietary vitamins can increase the ratio of facultative pathogenic bacteria and decrease the diversity of bacteria in the cecum of broilers. Our results provide new leads for further investigations on the interaction between dietary vitamin additives and the gut health of broilers.

Lean breed Landrace pigs harbor fecal methanogens at higher diversity and density than obese breed Erhualian pigs.

The diversity of fecal methanogens of Erhualian (obese type) and Landrace (lean type) pigs was examined using separate 16S rRNA gene libraries for each breed. A total of 763 clones were analyzed; 381 from the Erhualian library and 382 from the Landrace library were identified belonging to the genus Methanobrevibacter. Others were identified belonging to the genus Methanosphaera. The two libraries showed significant differences in diversity (P < 0.05) and composition (P < 0.0001). Only two operational taxonomic units (OTUs) were found in both libraries, whereas six OTUs were found only in the Erhualian library and 23 OTUs were found only in the Landrace library. Real-time PCR showed that the abundance of fecal methanogens in Landrace pigs was significantly higher than that in Erhualian pigs (P < 0.05). Results showed that the Landrace pig (lean) harbored a greater diversity and higher numbers of methanogen mcrA gene copies than the Erhualian pig (obese). These differences may be related to the fatness or leanness in these two pig breeds. The results provide new leads for further investigations on the fat storage of pigs or even humans.

[The intestinal microbiota and obesity of the host].

The growing population of overweight humans threatens both industrialized and developing countries and has been accompanied by obesity-related disorders, including type II diabetes, hypertension, cardiovascular pathology and nonalcoholic fatty liver disease. Recent researches have demonstrated that intestinal microbiota may be associated with the host's obesity. There were researches on the interaction between Bacteroides thetaiotaomicron and the energy metabolism of the host. Methanobrevibacer smithii had been improved to impact the host's energy metabolism through modulating the gene transcription of B. thetaiotaomicron. The microbiota can direct the host to increase hepatic production of triglycerides, promote storage of triglycerides in adipocytes through suppression of intestinal expression of a circulating LPL inhibitor, and have an effect on the host's energy deposition through the interaction with host's hormones (eg. Leptin) . Some metabolic products of the microbiota like SCFAs, other organic acids, alcohols and gases can be used by the host directly. Researches mentioned above are just started. According to the results above, some key points remain unknown. For example, the underlying mechanism of the interaction between microbiota or some unique microbes and the host, the procedure of dietary polysaccharides degradation of the microbes, and the relationship between the microbiota and the host's hormones. In this paper, the corresponding research results of author' s lab has also been reviewed and the future research prospect s have been summarized.