Starch hydrolysis by gut microbiota involves a diverse range of different enzymatic activities. Glucan-branching enzyme GlgB was identified as the most abundant glycosidase in Firmicutes in the swine intestine. GlgB converts α-(1→4)-linked amylose to form α-(1→4,6) branching points. This study aimed to characterize GlgB cloned from a swine intestinal metagenome and to investigate its potential role in formation of α-(1→4,6)-branched α-glucans from starch. The branching activity of purified GlgB was determined with six different starches and pure amylose by quantification of amylose after treatment. GlgB reduced the amylose content of all 6 starches and amylose by more than 85% and displayed a higher preference towards amylose. The observed activity on raw starch indicated a potential role in the primary starch degradation in the large intestine as an enzyme that solubilizes amylose. The oligosaccharide profile showed an increased concentration of oligosaccharide introduced by GlgB that is not hydrolyzed by intestinal enzymes. This corresponded to a reduced in vitro starch digestibility when compared to untreated starch. The study improves our understanding of colonic starch fermentation and may allow starch conversion to produce food products with reduced digestibility and improved quality.
Abstract Objective The gut microbiota is a complex ecosystem that shapes host metabolism, especially in early life. Maternal vaginal and gut microbiota is vertically transmitted to offspring during natural birth. Offspring born by cesarean section (CS) do not receive these bacteria and exhibit higher obesity risk later in life. The objective of this study was to examine differences in obesity risk between offspring born naturally (NB) or by CS to lean/obese dams. Methods Lean and obese rat dams gave birth to offspring naturally or by CS. Offspring obesity risk was analyzed via body weight/composition, food intake, sucrose preference, gut microbiota, and gene expression in gut and brain tissues. Results Obese (O)+CS offspring showed greater weight gain and caloric intake but a reduction in hypothalamic agouti related neuropeptide, neuropeptide Y, and interleukin 1β expression compared with O+NB offspring. Lean (L)+CS offspring had higher serum corticosterone concentration and reduced liver peroxisome proliferator‐activated receptor γ expression compared with L+NB. O+CS offspring had long‐term alterations to gut microbiota, including increased relative abundance of Faecalibaculum and reduced Muribaculaceae. Conclusions Overall, CS alters obesity risk differentially based on maternal obesity status. Further studies looking at the risks of obesity associated with CS are needed, with special attention paid to maternal obesity status and gut microbiota.
We thank Tabibian and Lindor for their comments on our article.1, 2 There are multiple challenges for establishing a pathogenic role for human betaretrovirus (HBRV) in primary biliary cirrhosis (PBC). Immune-based diagnostics are clearly required for conducting large-scale epidemiological studies, for example. Also, methods to measure low-level viral infection are necessary to link clinical improvement with diminished viral load in clinical trials of combination anti-viral therapy in PBC.3 Digital droplet PCR has shown promise in this area but linker-mediated PCR and next generation sequencing methods used in this study are too expensive and cumbersome.2 The concern that HBRV infection may just be an epiphenomenon is lessened somewhat by the association of viral infection with the mitochondrial phenotype observed in patients with PBC. The aberrant mitochondrial protein expression in virally infected biliary epithelium and lymph nodes has been documented in PBC patients4 and mouse models of autoimmune biliary disease.5 We agree that genetic susceptibility is probably a major factor that impacts on the development and extent of disease following infection. Indeed, the related agent, mouse mammary tumour virus (MMTV) is associated with a variety of inflammatory and neoplastic disorders in mice (lymphoma, breast and renal cancer) manifesting in different genetic backgrounds.5 Of relevance to detecting HBRV in normal individuals, diverse strains of mice have developed various mechanisms to control MMTV infection. For example, I/LnJ mice produce robust and sustained interferon-γ responses following MMTV infection and make neutralising antibodies that prevent viral spread.6 This may be of relevance to the viral hypothesis of PBC, as many genes within the IL-12 axis upstream of interferon-γ production have been implicated in genome-wide association studies as providing risk for the development of disease.7 Thus, further examination of the interaction of betaretrovirus infection with specific disease associated alleles is warranted to provide mechanistic insight how HBRV may become pathogenic in PBC patients. The authors’ declarations of personal and financial interests are unchanged from those in the original article.1
This study reports the development of a real time in situ analyzer for solids content measurement at different depths in oil sands tailings ponds. The analyzer uses an optical light scattering technique for the measurements and a low-level source (below license limits) gamma-ray transmission technique for in situ calibration. The technology has been successfully demonstrated at laboratory-scale, and a prototype is currently being developed for large-scale testing.
Early-life nutrition fundamentally influences newborn development and health. Here, we present a protocol for nutritional intervention in neonatal rats using the "pup-in-a-cup" artificial rearing system. We describe steps for rat milk substitute preparation, cheek cannulation and maintenance, and nutritional manipulation during the suckling period. This protocol enables investigation into the role of nutritional factors in newborns by artificially rearing rats away from the mother with experimental diets starting at postnatal day 4 for up to 18 days. For complete details on the use and execution of this protocol, please refer to Wang et al.,1 Choudhary et al.,2 and Mu et al.3,4
This study aimed to determine whether host-adapted lactobacilli exhibit superior survival during intestinal transit relative to nomadic and free-living organisms, and to characterize the impact of probiotic lactobacilli on autochthonous lactobacilli.Mixed cultures of Lactobacillus casei K9-1 and Lactobacillus fermentum K9-2, or reutericyclin producing Lactobacillus reuteri and its isogenic mutant were fed to piglets as freeze-dried culture, or as part of fermented feed. Lactobacilli in digesta and faecal samples were quantified by strain-specific quantitative PCR (qPCR), high-resolution-melting curve qPCR, and high-throughput sequencing of 16S rRNA gene sequence tags. The abundance of the host adapted L. reuteri in digesta and faeces was higher (P < 0·05) when compared to L. casei or L. fermentum. Feed fermentation or chemical acidification of feed reduced (P < 0·05) cell counts of Lactobacillus salivarius in colonic digesta. The reutericyclin producing L. reuteri TMW1.656 transiently reduced (P < 0·05) the faecal abundance of lactobacilli. However, the overall impact of probiotic intervention on autochthonous lactobacilli was minor.The vertebrate host-adapted L. reuteri survives better during intestinal transit of piglets compared to L. casei and L. fermentum.Ecology and lifestyle of Lactobacillus strains may be suitable criteria for selection of probiotic strains for use in swine production.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Water addition to natural-zeolite-catalyzed reactions significantly improves cracking of oilsands bitumen compared to analogous reactions in the absence of water. We report that the addition of 3% water to the catalyzed cracking reactions results in samples with lower viscosities and average molecular weights, less residue, olefin, and coke formation, and higher C2+ gas production compared to analogous reactions in the absence of water. Our study suggests that untreated natural zeolites undergo self-acidification by hydrolysis reactions in the presence of water. Fourier transform infrared spectroscopy and solid-state NMR analyses detected the presence of acid −OH groups on the raw untreated chabazite and clinoptilolite surfaces that are capable of supplying protons to initiate carbocation reactions. Stable isotopic mass spectrophotometric analyses on bitumen on D2O-doped catalytic reactions confirm up to ∼56% hydrogen incorporation from added water to the liquid products. Aromaticity and proton and deuterium distribution of products by liquid NMR indicate the occurrence of a number of catalytic reactions, including aromatization, rearrangement and substitution in the aliphatic chains, β-scission, dehydrogenation, and increased hydrogen enrichment at β- and γ-positions. On the basis of our findings, we postulate that water addition to natural zeolites generates catalytic reactions that involve carbocation on acid sites. Studies with model compounds such as cumene and hexadecane also demonstrated significant cracking activity with water addition.
Summary Background A human betaretrovirus (HBRV) has been linked with primary biliary cirrhosis ( PBC ) following the detection of viral particles in biliary epithelium by electron microscopy and cloning of the betaretrovirus genome from biliary epithelium and peri‐hepatic lymph nodes. Evidence for viral infection was found in the majority of PBC patients' peri‐hepatic lymph node samples. However, less than a third of the liver samples had detectable HBRV, whereas others were unable to detect betaretrovirus infection or noted the presence of virus in the liver of patients with other diagnoses. Aims To address the hypothesis that the betaretrovirus may be below the limits of detection in the liver, biliary epithelial cells (BEC) were investigated for the evidence of infection. Methods Ligation‐mediated PCR and next generation sequencing were used to detect proviral integrations in liver, lymph nodes and BEC isolated from liver transplant recipients. Hybridisation‐based assays were used to detect betaretroviral RNA in BEC. Results Unique HBRV integrations and betaretrovirus RNA were detected in the majority of biliary epithelia derived from patients with PBC , autoimmune hepatitis and cryptogenic liver disease but rarely in other liver transplant recipients with primary sclerosing cholangitis and other hepatic disorders. HBRV integrations were commonly found in PBC patients' lymph nodes but rarely in whole liver samples. Conclusions Human betaretrovirus infection is frequently observed at the site of disease in patients with primary biliary cirrhosis and also in biliary epithelium of patients with autoimmune hepatitis and cryptogenic liver disease.
Prenatal hair cortisol concentration is inconsistently associated with maternal psychological distress. However, prior studies have not often measured hair cortisol and maternal psychological distress prospectively over time, examined within-person associations, nor concurrently considered the complex hormonal milieu in which cortisol operates during pregnancy. We addressed these limitations and tested associations against a similar non-pregnant comparison group. Participants included 68 women (34 pregnant and 34 non-pregnant; Mage = 29.14 and 83 % White) from the Midwestern United States. Pregnant women were assessed each trimester, at 12, 26, and 38 weeks and non-pregnant women were assessed three times on the same schedule. At each assessment, participants completed measures of psychological distress and provided hair samples. The first 3 cm (from the scalp) of hair was assayed using enzyme immune-assay kits to reflect cumulative levels within the given trimester/3-month time period of cortisol, dehydroepiandrosterone (DHEA) and testosterone. Within-person associations of hair cortisol and ratio of hair cortisol-to-DHEA and cortisol-to-testosterone with psychological distress were assessed using multilevel models. There were positive within-person associations of hair cortisol with cumulative psychological distress (γ = 0.01, s.e. = 0.003, p = .049), anxiety (γ = 0.09, s.e. = 0.04, p = .046), and pregnancy-related anxiety symptoms (γ = 0.10, s.e. = 0.05, p = .041) in the pregnant sample such that on occasions when hair cortisol was higher than average so were psychological distress symptoms. No within-person associations of hair cortisol were supported in non-pregnant women although there was a negative within-person association, such that on occasions of having lower testosterone level than typical, depression symptoms were higher. There were no within-person associations of psychological distress and cortisol-to-DHEA ratio or cortisol-to-testosterone ratio in either the pregnant or non-pregnant sample. At the between person-level for pregnant women, lower cortisol levels were associated with higher perceived stress (γ = -0.28, s.e. = 0.09, p = .003) and depression symptoms (γ = -0.11, s.e. = 0.06, p = .039), whereas higher cortisol levels were associated with higher psychological distress (γ = 0.03, s.e. = 0.01, p = .010), state anxiety (γ = 0.33, s.e. = 0.13, p = .010), and depression symptoms (γ = 0.23, s.e. = 0.09, p = .017) in non-pregnant women. Modeling hair cortisol at the within-person and between-person level revealed differential findings in pregnant and non-pregnant women. Hair cortisol concentration, psychological distress, pregnancy, hormone coupling, within-person associations.
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