Amino acid metabolism in intestinal bacteria and its potential implications for mammalian reproduction

Reproduction is vital for producing offspring and preserving genetic resources. However, incidences of many reproductive disorders (e.g. miscarriage, intrauterine growth restriction, premature delivery and lower sperm quality) have either increased dramatically or remained at high rates over the last decades. Mounting evidence shows a strong correlation between enteral protein nutrition and reproduction. Besides serving as major nutrients in the diet, amino acids (AA) are signaling molecules in the regulation of diverse physiological processes, ranging from spermatogenesis to oocyte fertilization and to embryo implantation. Notably, the numbers of bacteria in the intestine exceed the numbers of host cells by 10 times. Microbes in the small-intestinal lumen actively metabolize large amounts of dietary AA and, therefore, affect the entry of AA into the portal circulation for whole-body utilization. Changes in the composition and abundance of AA-metabolizing bacteria in the gut during pregnancy, as well as their translocation to the uterus, may alter uterine function and epigenetic modifications of maternal physiology and metabolism, which are crucial for pregnancy recognition and fetal development. Thus, the presence of the maternal gut microbiota and AA metabolites in the intrauterine environments (e.g. endometrium and placenta) and breast milk is likely a unique signature for the programming of the whole-body microbiome and metabolism in both the fetus and infant. Dietary intervention with functional AA, probiotics and prebiotics to alter the abundance and activity of intestinal bacteria may ameliorate or prevent the development of metabolic syndrome, while improving reproductive performance in both males and females as well as their offspring.

Solexa sequencing of novel and differentially expressed microRNAs in testicular and ovarian tissues in Holstein cattle

The posttranscriptional gene regulation mediated by microRNA plays an important role in the development and function of male and female reproductive organs and germ cells in mammals, including cattle. In the present study, we identified novel and differentially expressed miRNAs in the testis and ovary in Holstein cattle by combining the Solexa sequencing with bioinformatics. In total 100 and 104 novel pre-miRNAs were identified in testicular and ovarian tissues, encoding 122 and 136 mature miRNAs, respectively. Of these, 6 miRNAs appear to be bovine-specific. A total of 246 known miRNAs were co-expressed in the testicular and ovarian tissues. Of the known miRNAs, twenty-one testis-specific and nine ovary-specific (1-23 reads) were found. Approximately 30.5% of the known bovine miRNAs in this study were found to have >2-fold differential expression within the two respective reproductive organ systems. The putative miRNA target genes of miRNAs were involved in pathways associated with reproductive physiology. Both known and novel tissue-specific miRNAs are expressed by Real-time quantitative PCR analysis in dairy cattle. This study expands the number of miRNAs known to be expressed in cattle. The patterns of miRNAs expression differed significantly between the bovine testicular and ovarian tissues, which provide important information on sex differences in miRNA expression. Diverse miRNAs may play an important regulatory role in the development of the reproductive organs in Holstein cattle.

Identification of splice variants, targeted microRNAs and functional single nucleotide polymorphisms of the BOLA-DQA2 gene in dairy cattle

Major histocompatibility complex, class II, DQ alpha 2, also named BOLA-DQA2, belongs to the Bovine Leukocyte Antigen (BOLA) class II genes which are involved in the immune response. To explore the variability of the BOLA-DQA2 gene and resistance to mastitis in cows, the splice variants (SV), targeted microRNAs (miRNAs), and single nucleotide polymorphisms (SNPs) were identified in this study. A new SV (BOLA-DQA2-SV1) lacking part of exon 3 (195 bp) and two 3'-untranslated regions (UTR) (52 bp+167 bp) of the BOLA-DQA2 gene was found in the healthy and mastitis-infected mammary gland tissues. Four of 13 new SNPs and multiple nucleotide polymorphisms resulted in amino acid changes in the protein and SNP (c. +1283 C>T) may affect the binding to the seed sequence of bta-miR-2318. Further, we detected the relative expressions of two BOLA-DQA2 transcripts and five candidated microRNAs binding to the 3'-UTR of two transcripts in the mammary gland tissues in dairy cattle by using the quantitative real-time polymerase chain reaction. The result showed that expression of the BOLA-DQA2-SV1 mRNA was significantly upregulated 2.67-fold (p<0.05) in mastitis-infected mammary tissues (n = 5) compared with the healthy mammary gland mammary tissues (n = 5). Except for bta-miR-1777a, miRNA expression (bta-miR-296, miR-2430, and miR-671) was upregulated 1.75 to 2.59-fold (p<0.05), whereas miR-2318 was downregulated in the mastitis cows. Our findings reveal that BOLA-DQA2-SV1 may play an important role in the mastitis resistance in dairy cattle. Whether the SNPs affect the structure of the BOLA-DQA2 gene or association with mastitis resistance is unknown and warrants further investigation.

One SNP in the 3'-UTR of HMGB1 gene affects the binding of target bta-miR-223 and is involved in mastitis in dairy cattle

High-mobility group box protein 1 (HMGB1) gene has a universal sentinel function for nucleic acid-mediated innate immune responses and acts as a pathogenic mediator in the inflammatory disease. In an effort to identify the functional single-nucleotide polymorphism (SNP) in the 3'-untranslated region (UTR) of the bovine HMGB1 gene that affects the binding to its target microRNA, first, the expression of HMGB1 mRNA in different genotypes and its candidate bta-miR-223 was investigated. Quantitative real-time polymerase chain reaction results showed that the relative expression of HMGB1 mRNA in cows with the genotype GG is significantly higher than those in cows with the genotype AA (P < 0.05). The expression of bta-miR-223 was significantly upregulated by 1.95-fold (P < 0.05) in the bovine mastitis-infected mammary gland tissues compared with that in the healthy tissues. Subsequently, luciferase assay indicated that the HMGB1 expression was directly targeted by bta-miR-223 in human embryo kidney 293 T (HEK 293T) cells. One novel SNP (g. +2776 A > G) in the HMGB1 3'-UTR, altering the binding of HMGB1 and bta-miR-223, was found to be associated with somatic count scores in cows. Taken together, the g. +2776 A > G-GG was an advantageous genotype which can be used as a candidate functional marker for mastitis resistance breeding program.

Effects of low-protein diet on the intestinal morphology, digestive enzyme activity, blood urea nitrogen, and gut microbiota and metabolites in weaned pigs

This study investigated the effects of low-protein diet supplemented with Lysine (Lys), Methionine (Met), Threonine (Thr), and Tryptophan (Trp) on small intestine morphology, enzyme activity, blood urea nitrogen, and gut microbiota and metabolites in weaned piglets. Eighteen weaned pigs weighing an average of 9.57 kg received one of three treatments: a normal protein diet with 20% crude protein (CP, diet [NP]), a moderately reduced protein diet with 17% CP (MP), or a low-protein diet with 14% CP (LP). All three diets were supplemented with Lys, Met, Thr and Trp to meet essential amino acid requirements for post-weaned piglets according to the NRC (2012). Following a 45 d study period, piglets on the LP and MP diets demonstrated atrophic small intestinal morphology, with decreased villus heights and lower ratios of villus height to crypt depth (p < 0.05); pepsin activity in the stomach was also reduced in these two groups (p < 0.05). Increased plasma cholesterol and decreased blood urea nitrogen presented in the MP and LP groups compared with the NP group (p < 0.05). Overall, gastrointestinal hormones were not affected by dietary protein levels with the exception of reduced somatostatin levels in the MP and LP groups. Jejunum and colon microbiota were not affected at either the phyla or genera level in any of the diets. Colonic ammonia nitrogen concentration was reduced in MP and LP groups. Dietary protein level had no effect on short chain fatty acids or biogenic amines. Our data suggest that reducing dietary protein levels by 3% (MP) or 6% (LP) in weaned pigs has the potential to decrease nitrogen emissions and impaired digestive capacity. Therefore, dietary protein level cannot be reduced by more than 3% in consideration of maladaptive changes to small intestinal morphology and pepsin activity in weaned piglets.

Progressive response of large intestinal bacterial community and fermentation to the stepwise decrease of dietary crude protein level in growing pigs

The study aimed to determine the effects of reduction of dietary crude protein (CP) level with balanced essential amino acids (EAA) on intestinal bacteria and their metabolites of growing pigs. Forty pigs (initial BW 13.50 ± 0.50 kg, 45 ± 2 days of age) were randomly assigned to four dietary treatments containing CP levels at 20.00% (normal crude protein, NP); 17.16% (medium crude protein, MP); 15.30% (low crude protein, LP); and 13.90% (extremely low crude protein, ELP), respectively. Crystalline AAs were added to meet the EAA requirement of pigs. After 4-week feeding, eight pigs per treatment (n = 8) were randomly selected and slaughtered for sampling of ileal, cecal, and colonic digesta and mucosa. Pigs with moderately reduced CP level had increased bacterial diversity, with the Shannon diversity indices for the colon digesta in the LP group and mucosa in the MP and LP groups significantly (P < 0.05) higher than those in the NP and ELP groups. As the CP level reduces, the Bifidobacterium population were linearly decreased (P < 0.05) both in ileum, cecum, and colon, and the ELP group had the lowest Bifidobacterium population in the cecum and colon, with its value significantly lower than NP and MP groups (P < 0.05). However, the ELP group had the highest population of Escherichia coli in the colon, with its value significantly higher than the LP group (P < 0.05). For bacterial metabolites, as CP level decreased, total short-chain fatty acid (T-SCFA), acetate, and butyrate were linearly increased (linear, P < 0.05) in the ileum, while all SCFAs except formate in the cecum and T-SCFA and acetate in the colon, were linearly decreased (P < 0.05). Reducing CP level led to a linear decrease of microbial crude protein (MCP) in the ileum (P < 0.05) and ammonia in all intestine segments (P < 0.05). The spermidine in cecum and total amines, cadaverine, methylamine, and spermidine in colon were shown a quadratic change (P < 0.05) as dietary CP decreases, with the highest concentration in LP group. These findings suggest that moderate reduction of dietary CP level may benefit large intestinal bacterial community and its fermentation, which was negatively affected by extremely low CP diet.

Effects of low dietary protein on the metabolites and microbial communities in the caecal digesta of piglets

Thirty-six healthy piglets (weighing 10 ± 1 kg; three animals per pen) were randomly allocated to two treatments: (i) a low protein diet (14% crude protein [CP]) supplemented with lysine, methionine, threonine and tryptophan (Group LP) and (ii) a normal protein diet (20% CP, Group NP), resulting in six replicate pens per treatment. One piglet from each pen was slaughtered at days 10, 25 and 45 of the experiment. For the whole experimental period of 45 d, Group LP had lower feed intake and daily gain and a higher feed-to-gain ratio compared with Group NP. At day 10, no effects on measured caecum metabolites were observed, but at days 25 and 45 in Group LP the concentration of ammonia-N, cadaverine, branched chain fatty acids and acetate were reduced. This was also true for the concentration of short chain fatty acids at day 45. The results of denaturing gradient gel electrophoresis showed that microbial diversity in Group LP was less abundant at day 25, but there was no difference at days 10 and 45. An unweighted pair group mean average analysis showed that the similarities were lower between Groups LP and NP at day 10 and higher at days 25 and 45. Quantitation results indicated that the numbers of Firmicutes and Clostridium cluster IV were lower in Group LP than in Group NP at day 25, but there were no differences at days 10 and 45. In conclusion, the low protein diet markedly reduced the metabolites of protein and carbohydrate fermentation and altered microbial communities in the caecal digesta of piglets.

Calcium-sensing receptor-mediated L-tryptophan-induced secretion of cholecystokinin and glucose-dependent insulinotropic peptide in swine duodenum

This study aimed to elucidate the effect of tryptophan (Trp) on gut hormone secretion as well as the roles of the calcium-sensing receptor (CaSR) and its downstream signaling pathway in gut hormone secretion by assessing swine duodenal perfusion in vitro. Swine duodenum was perfused with Krebs-Henseleit buffer as a basal solution. Various concentrations (0, 10, and 20 mM) of Trp were applied to investigate its effect on gut hormone secretion. A CaSR antagonist was used to detect the involvement of CaSR and its signal molecules. The 20 mM Trp concentration promoted the secretion of cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP), elevated the mRNA level of CaSR, and upregulated the protein levels of CaSR, protein kinase C (PKC), and inositol trisphosphate receptor (IP3R). However, NPS 2143, an inhibitor of CaSR, attenuated the CCK and GIP release, reduced the mRNA level of CaSR, and decreased the protein levels of CaSR, PKC, and IP3R with 20 mM Trp perfusion. The results indicate that CCK and GIP secretion can be induced by Trp in swine duodenum in vitro, and the effect is mediated by CaSR and its downstream signal molecules PKC and IP3R.

Multiple promoters and targeted microRNAs direct the expressions of HMGB3 gene transcripts in dairy cattle

HMGB3 (high-mobility group box 3) is an X-linked member of a family of sequence-independent chromatin-binding proteins and functions as a universal sentinel for nucleic acid-mediated innate immune responses. The splice variant expression, promoter characterization and targeted microRNAs of the bovine HMGB3 gene were investigated to explore its expression pattern and possible regulatory mechanism. The results revealed that the expression of HMGB3 transcript variants 1 and 2 (HMGB3-TV1 and HMGB3-TV2) mRNA in the mastitis-infected mammary gland tissues was up-regulated by 8.46- and 5.31-fold respectively compared with that in healthy tissues (P < 0.05). HMGB3-TV1 was highly expressed in the mammary gland tissues, whereas HMGB3-TV2 was expressed primarily in liver. Functional analyses indicated that HMGB3 transcription is regulated by three distinct promoters - promoters 1, 2 and 3 (P1, P2 and P3) - resulting in two alternative transcripts with the same 3'-untranslated region. Promoter luciferase activity analysis suggested that the core sequences of P1 and P2 were mapped in the region of g.1535 to ~g.2076 and g.2074 to ~g.2491 respectively. The g.5880C>T SNP in P3 affected its base promoter activity, and different genotypes were associated with the bovine somatic count score. The expression of targets bovine miR-17-5p, miR-20b and miR-93 of the HMGB3 gene was down-regulated 1.56-, 1.72- and 2.94-fold respectively in mammary gland tissues as compared with that in healthy tissues (P < 0.05). The findings suggest that HMGB3 expression is under complex transcriptional and post-transcriptional control by alternate promoter usage, alternative splicing mechanism and microRNAs in dairy cattle.

Sensing of L-Arginine by Gut-Expressed Calcium Sensing Receptor Stimulates Gut Satiety Hormones Cholecystokinin and Glucose-Dependent Insulinotropic Peptide Secretion in Pig Model

Nutrients regulate the secretion of gut satiety hormones, which is related to the modulation of food intake and blood glucose levels. Calcium-sensing receptor (CaSR) is involved in regulating gut hormone secretion in response to l-amino acids and multivalent cations. Rodents are often used to investigate the effect of nutrients on these hormonal release. However, results obtained using rodent models are difficult to be applied in humans, we used pigs as a model in this study because their physiology is similar to that of humans. In this study, we investigated whether l-Arginine (l-Arg) could induce gut hormones cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP) secretion in the porcine duodenum and if so, whether CaSR mediated l-Arg-regulated gut satiety hormone secretion. Our data showed that treatment with 20 and 50 mM l-Arg induced CCK and GIP secretion compared with 0 mM l-Arg. However, treatment with d-Arg (an inactive isomer) failed to elicit this response. The potency of l-Arg to induce CCK and GIP secretion was enhanced in the presence of extracellular Ca²⁺ and CaSR agonist cinacalcet. However, the effect of Arg on CCK and GIP secretion was attenuated by blocking CaSR and its downstream signaling molecules adenylate cyclase (AC) and phospholipase C (PLC). Taken all together, pig duodenum provides an appropriate model to explore the effects of l-Arg on the secretion of the satiety-related gut hormones CCK and GIP and the role of CaSR in this effect. Further investigations are needed to verify the effect of l-Arg on food intake and blood glucose in human study. PRACTICAL APPLICATION: l-Arginine is able to modulate cholecystokinin and glucose-dependent insulinotropic peptide secretion through the CaSR in pig model, which has a potential role in regulating food intake and blood glucose levels.

Phenylalanine and tryptophan stimulate gastrin and somatostatin secretion and H+-K+-ATPase activity in pigs through calcium-sensing receptor

In rodents and humans, aromatic amino acids increase gut hormone secretion and H⁺-K⁺-ATPase activity by modulating calcium-sensing receptor (CaSR). However, the role of CaSR and its related signaling molecules in amino acid-induced gut hormone secretion in swine has not been investigated. Here, we examined whether a CaSR-dependent pathway modulated gastrin and somatostatin (SS) secretion and H⁺-K⁺-ATPase activity in pigs. Perfusion of pig stomach tissues in the presence of extracellular 80 mM l-phenylalanine (Phe) or 20 mM l-tryptophan (Trp) and a CaSR agonist cinacalcet triggered gastrin and SS secretion and H⁺-K⁺-ATPase activity (P < 0.05) and increased CaSR expression (P < 0.05). This effect of Phe and Trp was dependent on Ca²⁺ (P < 0.05) and was abolished after treatment with NPS 2143, an inhibitor of CaSR, and 2-aminoethyl diphenyl borinate, an inhibitor of CaSR downstream signaling molecule inositol 1,4,5-triphosphate receptor (IP₃R). These findings indicate that Phe and Trp induce Ca²⁺-dependent gastrin and SS secretion and H⁺-K⁺-ATPase activity through CaSR and its downstream signaling molecule IP₃R.

Toxicity of 6PPD-quinone to four freshwater invertebrate species

The antioxidant N-(1,3-Dimethylbutyl)-N'-phenyl-p- phenylenediamine (6PPD) is used to protect the rubber in tires from oxidation, which extends the life of the tire. When oxidized, 6PPD is transformed into 6PPD-quinone (6PPDQ). 6PPDQ, along with other tire ingredients, can enter aquatic ecosystems through the transport of tire wear particles in runoff during a precipitation event. The mass mortality of coho salmon following precipitation events in urban areas lead to the discovery that 6PPDQ is the likely cause due to coho salmon's relatively high sensitivity to 6PPDQ. The assessment of 6PPDQ toxicity to other aquatic species has expanded, but it has focused on fish. This study investigated the toxicity of 6PPDQ to four freshwater invertebrate species, larval burrowing mayfly (Hexagenia spp.), juvenile cladoceran (Daphnia magna), file ramshorn snail embryo (Planorbella pilsbryi), and adult washboard mussel (Megalonaias nervosa). For all four species, the highest concentration of 6PPDQ tested did not result in significant mortality. This translated into the determination of the highest concentration that did not cause significant mortality (NOEC) for Hexagenia spp., D. magna, P. pilsbryi, and M. nervosa of 232.0, 42.0, 11.7, and 17.9 μg/L, respectively. The data from this study indicate that freshwater invertebrates are not as sensitive to 6PPDQ as some salmonid species (e.g., coho salmon Oncorhynchus kisutch). This study also analyzed 6PPDQ in road runoff from around the city of Guelph in Ontario, Canada. 6PPQ was detected in all samples but the concentration was two orders of magnitude lower than the NOECs for the four tested species of freshwater invertebrate.

Soybean protein hydrolysate stimulated cholecystokinin secretion and inhibited feed intake through calcium-sensing receptors and intracellular calcium signalling in pigs

Although soybean protein is the major component in livestock feeds, its effect on pigs' appetites is largely unknown. Recently, the importance of gut nutrient-sensing for appetite modulation by regulating anorectic gut hormone release has been recognised. This study investigates the roles of soybean proteins in appetite regulation, anorectic gut hormone secretion, and underlying mechanisms. The duodenal-cannulated piglets were used to evaluate the effects of soybean protein hydrolysate (SPH) on feed intake and anorectic hormone release, including cholecystokinin (CCK), peptide YY (PYY), glucagon-like peptide 1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) in the hepatic vein by infusing SPH. Identifying which nutrient-sensing receptor in pig duodenum response to SPH stimulation for gut hormone release was conducted. Using its antagonist, the role of the identified receptor in feed intake and anorectic hormone release was also investigated. Combination with an ex vivo perfusion system, the possible mechanism by which SPH exerts the effects in porcine duodenum was further illustrated. Results in vivo showed that intraduodenal infusion of SPH inhibited short-term feed intake in pigs and promoted CCK, PYY, and GIP secretion in the hepatic vein. SPH also increased duodenum calcium-sensing receptor (CaSR) expression. Pre-treated with CaSR antagonist NPS 2143, the feed intake of pigs tended to be attenuated by SPH (P = 0.09), and CCK release was also suppressed (P < 0.05), indicating that CaSR was involved in SPH-stimulated CCK release and inhibited feed intake in pigs. The ex vivo perfused duodenum tissues revealed that SPH-triggered CCK secretion was likeliest due to the activation of the intracellular Ca²⁺/TRPM5 pathway. Overall, this study's result illustrates that the diet soybean protein might decrease appetite in pigs by triggering duodenum CCK secretion by activating CaSR and the intracellular Ca²⁺/TRPM5 pathway.

Oral administration of Moringa oleifera leaf powder relieves oxidative stress, modulates mucosal immune response and cecal microbiota after exposure to heat stress in New Zealand White rabbits

Background

Heat stress (HS) disrupts the gut barrier allowing the uptake of lipopolysaccharide (LPS) and leads to an inflammatory response and changes in gut microbiota composition. Moringa oleifera leaf powder (MOLP) has been proposed to combat HS, yet its alleviate role is currently under investigation. The current study investigated the effects of chronic HS and MOLP supplementation on changes in redox status and immune response of cecal mucosa along with alteration in cecal microbiota.

Methods

A total of 21 young New Zealand White (NZW) rabbits (male) about 32 weeks old (mean body weight of 3318 ± 171 g) reared on a commercial pelleted diet were employed; divided into three groups (n = 7): control (CON, 25 °C), heat stress (HS, 35 °C for 7 h daily), and HS supplemented orally with MOLP (HSM, 35 °C) at 200 mg/kg body weight per day for 4 weeks.

Results

The results demonstrated that MOLP supplementation increased organ index of cecal tissue compared with the HS group (P > 0.05). Levels of malonaldehyde (MDA) and activity of superoxide dismutase (SOD) as well as lactate dehydrogenase (LDH) were reduced in the cecal mucosa of the HSM group compared with the HS group. MOLP downregulated the contents of cecal mucosa LPS, several inflammatory markers (TNF-α/IL-1α/IL-1β), and myeloperoxidase (MPO) in the HSM group (P < 0.05). Secretory immunoglobulin A (SIgA) was increased in the HSM group compared with the HS group (P < 0.05). The transcriptome of cecal mucosa showed that MOLP reduced gene expression relative to several immune factors, including IL-10, IFNG, and RLA, whereas both HS and MOLP increased the gene expression of fat digestion and absorption pathway, including APOA1, FABP1, FABP2, MTTP, and LOC100344166, compared to the CON group (P < 0.001). At the phylum level, the relative abundance of Proteobacteria was increased by HS, while Actinobacteria was significantly increased by HSM compared to other groups (P < 0.05). At genus level, Papillibacter was higher in abundance in HSM groups compared to CON and HS groups (P < 0.05). Higher butyrate concentrations were observed in the HSM group than HS and CON groups (P < 0.05).

Conclusion

In conclusion, HS in growing rabbits resulted in alteration of cecal microbiota at phyla level as well as increased oxidative stress and expression of mucosal inflammatory genes. Whereas, oral MOLP supplementation elevated the relative weight of cecum, affected their immunological and cecal micro-ecosystem function by improving antioxidant status and down-regulating mucosal tissue inflammatory response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00586-y.

Behavior of 14C-atrazine in Argentinean topsoils under different cropping managements

Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) behavior was studied in four surface soils during incubations in laboratory conditions. Soils were chosen in relation to their cropping management (tillage and no tillage) and crop rotation system (continuous soybean [Glycine mar (L.) Merr.] and maize (Zea mays L.)-soybean rotation). A natural soil under brushwood was sampled as a reference. Atrazine use in field conditions was associated with maize cropping, thus only one soil received atrazine every other year. Atrazine behavior was characterized through the balance of 14C-U-ring atrazine radioactivity among the mineralized fraction, the extractable fraction, and the nonextractable bound residues. Soil organic matter capacity to form bound residues was characterized using soil size fractionation. Accelerated atrazine mineralization was only observed in the soil receiving atrazine in field conditions. Atrazine application every other year was enough to develop a microflora adapted to triazine ring mineralization. Bound residue formation was rapid and increased with soil organic matter content. The coarsest soil size fractions (2000-200 and 200-50 microm) containing the nonhumified organic matter presented the highest capacity to form bound residues. No effect of tillage system was observed, probably because of the uniform sampling depth at 20 cm, hiding the stratification pattern of soil organic matter in non-tilled soils.

Diversity of butyrivibrio group bacteria in the rumen of goats and its response to the supplementation of garlic oil

This study aimed to investigate the diversity of the Butyrivibrio group bacteria in goat rumen and its response to garlic oil (GO) supplementation as revealed by molecular analysis of cloned 16S rRNA genes. Six wethers fitted with ruminal fistulas were assigned to two groups for a cross-over design with 28-d experimental period and 14-d interval. Goats were fed a basal diet without (control) or with GO ruminal infusion (0.8 g/d). Ruminal contents were used for DNA extraction collected before morning feeding on d 28. A total bacterial clone library was firstly constructed by nearly full-length 16S rRNA gene cloned sequences using universal primers. The resulting plasmids selected by Butyrivibrio-specific primers were used to construct a Butyrivibrio group-specific bacterial clone library. Butyrivibrio group represented 12.98% and 10.95% of total bacteria in control and GO group, respectively. In libraries, clones were classified to the genus Pseudobutyrivibrio, Butyrivibrio and others within the family Lachnospiraceae. Additionally, some specific clones were observed in GO group, being classified to the genus Ruminococcus and others within the family Ruminococcaceae. Based on the criterion that the similarity was 97% or greater with database sequences, there were 29.73% and 18.42% of clones identified as known isolates (i.e. B. proteoclasticus and Ps. ruminis) in control and GO groups, respectively. Further clones identified as B. fibrisolvens (5.41%) and R. flavefaciens (7.89%) were specifically found in control and GO groups, respectively. The majority of clones resembled Ps. ruminis (98% to 99% similarity), except for Lachnospiraceae bacteria (87% to 92% similarity) in the two libraries. The two clone libraries also appeared different in Shannon diversity index (control 2.47 and GO group 2.91). Our results indicated that the Butyrivibrio group bacteria had a complex community with considerable unknown species in the goat rumen.

Effects of garlic oil on milk fatty acid profile and lipogenesis-related gene expression in mammary gland of dairy goats

BACKGROUND

Garlic oil (GO) has blood lipid-lowering effects. Milk fatty acid (FA) originates partly from plasma, and can be affected by the mammary lipogenesis. This study aimed to investigate GO effects on milk FA profile and mammary lipogenesis-related gene expression. Early-lactation goats were randomly allocated to four treatments with six goats each, and offered corn silage ad libitum and fixed amount of 0.79 kg day(-1) dry matter (DM) concentrate mixed with GO (0, 0.57, 1.14, 1.71 g kg(-1) DM) for 30 days consisting of 26-day adaptation.

RESULTS

Intake of corn silage reduced (P≤0.05) as GO level increased in the concentrate. Lipase activity and lactose content linearly increased, while non-esterified FA concentration quadratically decreased with increasing GO level (P≤0.05). The proportions of short- and medium-chain (C14:0, C15:0 and C16:0) and saturated FA decreased, whereas C18, cis9 trans11 conjugated linoleic acid (c9t11 CLA), t10c12 CLA, monounsaturated and polyunsaturated FA, and some ≥ C20 FA proportions increased in a linear manner with increasing GO level (P≤0.05). The mRNA abundance of genes remained unchanged (P > 0.1) as GO level increased.

CONCLUSION

Garlic oil altered milk FA profile and these effects may not be related to the mammary lipogenesis-related genes expression.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Supplementation of Moringa oleifera leaf powder orally improved productive performance by enhancing the intestinal health in rabbits under chronic heat stress

Heat stress jeopardizes animal's growth and health mainly through induction of oxidative stress and inflammation. The current study investigated the effects of Moringa oleifera leaf powder (MOLP) supplementation on productive performance and intestinal health of rabbits under chronic heat stress (HS). Young New Zealand White rabbits (male) at the age of 32 weeks (n = 21, mean body weight of 3318 ± 171 g) for four weeks' period were reared on commercial pelleted diet and divided into three groups: control (CON, 25 °C), HS (35 ± 1 °C) and HS (35 ± 1 °C) with MOLP (HSM) supplemented orally (200 mg/kg body weight). The results demonstrated that rabbits in the HSM group had reduced rectal temperature, respiration rate and improved FCR due to improved daily gain and better crude fiber (NDF) digestibility (P < 0.05) compared with HS group. MOLP improved intestinal integrity and function as indicated by lower serum diamine oxidase level and increased jejunal weight, length, villus height and ratio of villus height to crypt depth than heat-stressed rabbits. MOLP reversed the increased levels of serum cortisol, metabolic indicators i.e. glucose, insulin, and reduced concentrations of serum triiodothyronine. MOLP supplementation also significantly down-regulated the mRNA expression of tumor necrosis factor alpha (α), heat shock protein A2, glutathione peroxidase-1, interleukin (IL)-1α and increased the expression of IL-6. In conclusion, MOLP supplementation could enhance intestinal health along with production and metabolic indicators by alleviating the oxidative stress and inflammatory response in small intestine of hyper-thermic rabbits.

Dietary Moringa oleifera leaf powder improves jejunal permeability and digestive function by modulating the microbiota composition and mucosal immunity in heat stressed rabbits

Heat stress (HS) has detrimental effects on intestinal health by altering digestive and immune responses in animals. Dietary Moringa oleifera leaf powder (MOLP) has been implicated in ameliorating the impact of HS, but its effects in terms of intestinal function improvement under HS remain poorly characterized. Therefore, the current study investigated the impact of HS and MOLP supplementation on tight junction barriers, intestinal microbiota (jejunal digesta), and differentially expressed genes (DEGs) in jejunal mucosa of heat-stressed rabbits by using the next-generation sequencing techniques. A total of 21 male New Zealand White rabbits (32 weeks old mean body weight of 3318 ± 171 g) were divided into three groups (n = 7/group) as control (CON, 25 °C), heat stress (HS, 35 °C for 7 h daily), and HS with MOLP supplementation (HSM, 35 °C for 7 h daily) gavage at 200 mg/kg body weight per day for 4 weeks. The results indicated that MOLP supplementation increased mRNA expression of tight junction proteins and glutathione transferase activity, while the malonaldehyde concentration was decreased in the jejunal mucosa compared to HS group (P < 0.05). Furthermore, MOLP decreased the concentrations of lipopolysaccharide, pro-inflammatory cytokines, and myeloperoxidase compared with HS group (P < 0.05). Intestinal microbiota analysis revealed that at phyla level, the relative abundance of Bacteroidetes was higher in HSM group compared to CON and HS groups. MOLP supplementation also resulted in higher abundance of putatively health-associated genera such as Christensenellaceae R-7 gut group, Ruminococcaceae NK4A214 group, Ruminococcus 2, Lachnospiraceae NK4A136 group, and Lachnospiraceae unclassified along with higher butyrate levels in HSM group as compared to HS group. The analysis of DEGs revealed that MOLP reversed inflammatory response by downregulation of genes, such as TNFRSF13C, LBP, and COX2 in enriched KEGG pathway of NF-kβ pathway. MOLP supplementation also significantly upregulated the expression of genes in protein digestion and absorption pathway, including PRSS2, LOC100349163, CPA1, CPB1, SLC9A3, SLC1A1, and SLC7A9 in HSM group. Three genes of fibrillar collagens, i.e., COL3A1, COL5A3, and COL12A1 in protein digestion were also down-regulated in HSM group. In conclusion, MOLP supplementation could improve jejunal permeability and digestive function, positively modulate microbiota composition and mucosal immunity in heat-stressed rabbits.

Effects of the increased protein level in small intestine on the colonic microbiota, inflammation and barrier function in growing pigs

Background

An increased level of the dietary protein alters the colonic microbial community and metabolic profile of pigs, but it remains unclear whether this leads to colonic inflammation and impairs barrier function in growing pigs.

Results

Sixteen pigs (35.2 ± 0.3 kg) were infused with sterile saline (control) or soy protein hydrolysate (SPH) (70 g/day) through a duodenal fistula twice daily during a 15-day experimental period. The SPH treatment did not affect their average daily feed intake and daily weight gain (P > 0.05), but reduced colon index and length (P < 0.05). Illumina MiSeq sequencing revealed that species richness was increased following SPH intervention (P < 0.05). Furthermore, SPH reduced the abundance of butyrate- and propionate-producing bacteria—such as Lachnospiraceae NK4A136 group, Lachnospiraceae_uncultured, Coprococcus 3, Lachnospiraceae UCG-002, and Anaerovibrio—and increased the abundance of potentially pathogenic bacteria and protein-fermenting bacteria, such as Escherichia-Shigella, Dialister, Veillonella, Prevotella, Candidatus Saccharimonas, Erysipelotrichaceae UCG-006, Prevotellaceae_uncultured, and Prevotellaceae UCG-003 (P < 0.05). In addition, a lower content of total short-chain fatty acids, propionate, and butyrate and a higher concentration of cadaverine, putrescine, total biogenic amines, ammonia, and isovalerate were observed following SPH infusion (P < 0.05). Further analysis revealed that SPH increased the concentration of tumour necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-8 in the colonic mucosa (P < 0.05). Interestingly, SPH intervention increased the expression of occludin, zonula occludens (ZO)-1, and claudin-1 in colonic mucosa (P < 0.05). Correlation analysis showed that different genera were significantly related to the production of metabolites and the concentrations of pro-inflammatory cytokines.

Conclusion

An increased soy protein level in the small intestine altered the colonic microbial composition and metabolic profile, which resulted in the secretion of colonic proinflammatory cytokines and the increased expression of tight junction proteins.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02498-x.

l-Glutamate stimulates cholecystokinin secretion via the T1R1/T1R3 mediated PLC/TRPM5 transduction pathway

BACKGROUND

It is known that cholecystokinin (CCK) plays an essential role in reducing food intake and driving weight loss. Previous studies demonstrated that amino acids were capable of triggering CCK release through G protein-coupled receptors, but the sensing mechanism remains obscure, especially the intracellular signaling pathway.

RESULTS

l-Glu, rather than its d-isomer, robustly stimulated CCK secretion in a porcine duodenal model, and the secretory response was augmented by incubation with the allosteric ligand of T1R1, while T1R3 antagonist attenuated it. Upon inhibiting phospholipase C (PLC) or transient receptor potential M5 (TRPM5) activity, l-Glu failed to increase CCK release. Oral administration of monosodium glutamate in rats also suppressed food intake and increased plasma CCK levels, accompanied by elevated expression of T1R1, PLCβ2 and TRPM5 in the duodenum.

CONCLUSION

These data demonstrated that l-Glu stimulated CCK secretion through the activation of T1R1/T1R3 in a PLC/TRPM5-dependent manner. © 2020 Society of Chemical Industry.

Combination of fermentation and enzymolysis enhances bioactive components and function of de-oiled rice bran

BACKGROUND

De-oiled rice bran (DORB), a substantial yet underutilized byproduct of rice processing, boasts a rich composition of active ingredients but suffers from limited application. Previous studies have indicated that enzymatic or fermentation treatments enhanced these active components. In this study, lactobacilli and complex enzymes were employed to co-treat DORB, involving the determination of the changes in active components and functionalities of DORB extract (DORBE) before and after this treatment.

RESULTS

Following fermentation-enzymolysis, the total phenol and total flavonoid contents in DORBE were significantly increased by 43.59% and 55.10%, reaching 19.66 and 34.34 g kg-1, respectively. Antioxidant tests in vitro demonstrated that the co-treatment enhanced the scavenging activities of DPPH, hydroxyl and ABTS radicals. Porcine intestinal epithelial cell experiments revealed that, compared to DORBE, the fermentation and enzymolysis DORBE (FDORBE) exhibited significantly improved cell viability and catalase activity as well as scavenging capacity for reactive oxygen species and malondialdehyde after induction by H2O2. Furthermore, FDORBE restored the decreased mRNA expression levels of Nrf2, HO-1 and NQO1 in the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway stimulated by H2O2.

CONCLUSION

Fermentation-enzymolysis co-treatment increases the contents of bioactive components of DORBE and enhances its antioxidant capacity, leading to a better protection against intestinal disorders induced by oxidative stress, suggesting that this co-treatment is a rational and effective strategy to increase the value of grains and promotes the use of DORB as a functional feed in animal production. © 2024 Society of Chemical Industry.