Gut microbiota affects the host's metabolism, and it is suggested that there are differences in gut microbiota composition between patients with type 2 diabetes and healthy individuals. Additionally, dysbiosis may increase the concentration of lipopolysaccharides (LPS), causing metabolic endotoxemia, which induces impaired glucose tolerance. Several studies have reported relationships between metabolic diseases and the gut microbiota; and prebiotics, such as oligosaccharides, are commonly consumed to regulate gut microbiotas in healthy individuals. Galacto-oligosaccharides (GOS) are a major prebiotic, which specifically increase Bifidobacteriaceae abundance. Recent studies have reported that Bifidobacteriaceae improved metabolic endotoxemia or impaired glucose tolerance. However, there are few studies reporting the effects of GOS on patients with type 2 diabetes. In the current study, we compared clinical parameters, faecal gut microbiota, their associated metabolic products and their components such as LPS, and LPS-binding protein (LBP) produced by the host, between patients with diabetes and healthy controls. We then assessed the effects of GOS on glycaemic control, and gut microbiotas and metabolites in patients with type 2 diabetes in a double-blind controlled manner. LBP levels were significantly higher in patients with diabetes than those of healthy subjects, which was consistent with previous reports. The abundance of Bifidobacteriaceae and the diversity of intestinal microbiota were significantly lower in patients with diabetes than in healthy subjects. Interestingly, Bifidobacteriaceae was markedly restored in patients with diabetes after consumption of GOS, whereas LBP and glucose tolerance did not improve during this short-term trial period. In the present study, we demonstrated that GOS can ameliorate dysbiosis in patients with diabetes, and continuous intake of GOS may be a promising method for managing type 2 diabetes.

We report here a functional analysis of spo5 ؉ (mug12 ؉ ) of Schizosaccharomyces pombe, which encodes a putative RNA-binding protein. The disruption of spo5 ؉ caused abnormal sporulation, generating inviable spores due to failed forespore membrane formation and the absence of a spore wall, as determined by electron microscopy. Spo5 regulates the progression of meiosis I because spo5 mutant cells display normal premeiotic DNA synthesis and the timely initiation of meiosis I but they show a delay in the peaking of cells with two nuclei, abnormal tyrosine 15 dephosphorylation of Cdc2, incomplete degradation of Cdc13, retarded formation and repair of double strand breaks, and a reduced frequency of intragenic recombination. Immunostaining showed that Spo5-green fluorescent protein (GFP) appeared in the cytoplasm at the horsetail phase, peaked around the metaphase I to anaphase I transition, and suddenly disappeared after anaphase II. Images of Spo5-GFP in living cells revealed that Spo5 forms a dot in the nucleus at prophase I that colocalized with the Mei2 dot. Unlike the Mei2 dot, however, the Spo5 dot was observed even in sme2⌬ cells. Taken together, we conclude that Spo5 is a novel regulator of meiosis I and that it may function in the vicinity of the Mei2 dot.

AbstractsTubulointerstitial injury is central to the progression of end‐stage renal disease. Recent studies have revealed that one of the most investigated uremic toxins, indoxyl sulfate (IS), caused tubulointerstitial injury through oxidative stress and endoplasmic reticulum (ER) stress. Because indole, the precursor of IS, is synthesized from dietary tryptophan by the gut microbiota, we hypothesized that the intervention targeting the gut microbiota in kidney disease with galacto‐oligosaccharides (GOS) would attenuate renal injury. After 2 weeks of GOS administration for 5/6 nephrectomized (Nx) or sham‐operated (Sham) rats, cecal indole and serum IS were measured, renal injury was evaluated, and the effects of GOS on the gut microbiota were examined using pyrosequencing methods. Cecal indole and serum IS were significantly decreased and renal injury was improved with decreased infiltrating macrophages in GOS‐treated Nx rats. The expression levels of ER stress markers and apoptosis were significantly increased in the Nx rats and decreased with GOS. The microbiota analysis indicated that GOS significantly increased three bacterial families and decreased five families in the Nx rats. In addition, the analysis also revealed that the bacterial family Clostridiaceae was significantly increased in the Nx rats compared with the Sham rats and decreased with GOS. Taken altogether, our data show that GOS decreased cecal indole and serum IS, attenuated renal injury, and modified the gut microbiota in the Nx rats, and that the gut microbiota were altered in kidney disease. GOS could be a novel therapeutic agent to protect against renal injury.

Arabinoxylan hydrolysates (AXH) are the hydrolyzed products of the major components of dietary fibers, arabinoxylan. AXH include diverse oligosaccharides varying in xylose polymerization and side residue modifications with arabinose at the O-2 and/or O-3 positions of the xylose unit. Previous studies have reported that AXH exhibit prebiotic properties on gut bifidobacteria; moreover, several adult-associated bifidobacterial species (e.g., Bifidobacterium adolescentis and Bifidobacterium longum ssp. longum) are known to utilize AXH. In this study, we tried to elucidate the molecular mechanisms of AXH utilization by Bifidobacterium pseudocatenulatum, which is a common bifidobacterial species found in adult feces. We performed RNA-seq transcriptomic analysis of B. pseudocatenulatum YIT 4072T, which identified three up-regulated gene clusters during AXH utilization. The gene clusters encoded three sets of ATP-binding cassette (ABC) transporters and five enzymes belonging to the glycoside hydrolase family 43 (GH43). By characterizing the recombinant proteins, we found that three solute-binding proteins of ABC transporters showed either broad or narrow specificity: two arabinofuranosidases hydrolyze either single- or double-decorated arabinoxylooligosaccharides: three xylosidases exhibited functionally identical activity. These data collectively suggest that the transporters and glycoside hydrolases, encoded in the three gene clusters, work together to utilize AXH of different sizes and side residue modifications. Thus, our study sheds light on the overall picture of how these proteins collaborate for utilization of AXH in B. pseudocatenulatum, and may explain the predominance of this symbiont species in the adult human gut. Importance Bifidobacteria commonly reside in the human intestine and possess abundant genes involved in carbohydrate utilization. Arabinoxylan hydrolysates (AXH) are hydrolyzed products of arabinoxylan, one of the most abundant dietary fibers, and they include xylooligosaccharides and those decorated with arabinofuranosyl residues. The molecular mechanism by which B. pseudocatenulatum, a common bifidobacterial species found in adult feces, utilizes structurally and compositionally variable AXH is yet to be extensively investigated. In this study, we identified three gene clusters (encoding five GH43 enzymes and three solute-binding proteins of ABC transporters) that were up-regulated in B. pseudocatenulatum YIT 4072T during AXH utilization. By investigating their substrate specificities, we revealed how these proteins are involved in the uptake and degradation of AXH. These molecular insights may provide a better understanding of how resident bifidobacteria colonize the colon.

Objectives To evaluate the efficacy of fermented milk containing Lactobacillus casei strain Shirota (LcS) on the incidence of constipation, diarrhea, acute respiratory infections (ARI), and nutritional status of young Vietnamese children. Methods A controlled field trial was conducted with 1003 children (3–5 years old) in Thanh Hoa province in Vietnam. The probiotic group (n = 510) consumed fermented milk 65 mL/day containing 108 CFU/mL of LcS for the 12-week intervention period, whereas the control group (n = 493) was not given any. The incidence of constipation, diarrhea, ARI, and anthropometry in children was determined at baseline, after 4, 8, and 12-week intervention, and after the 4-week follow-up period. Results Probiotic drink decreased the incidence of constipation after the 12-week intervention period (12.0% vs. 32.0%, OR = 0.28 (95% CI: 0.21–0.40), p < 0.001), tended to decrease the incidence of diarrhea (4.9% vs. 7.9%, OR = 0.60 (95% CI: 0.35–1.01), p = 0.068), and prevented the occurrence of ARI (15.9% vs. 24.5%, OR = 0.58 (95% CI: 0.42–0.79), p < 0.001), when compared with the control group. In contrast, no probiotic effects were observed for the duration of diarrhea or ARI. Weight gain was higher in the probiotic group than in the control group after 4, 8, and 12-week intervention and after the 4-week follow-up period (p < 0.05). Conclusions Daily intake of fermented milk containing LcS strongly prevented the incidence of constipation and ARI in Vietnamese children. This study also revealed the potential effects of the use of a probiotic drink on diarrhea prevention as well as nutritional status improvement.

Galactooligosaccharides (GOS) are mixed oligosaccharides that are mainly composed of galactosyllactoses (GLs), which include 3¢-GL, 4¢-GL, and 6¢-GL. Data from numerous in vitro and in vivo studies have shown that GOS selectively stimulate the growth of bifidobacteria. Previously, we identified the gene locus responsible for 4¢-GL utilization, but the selective routes of uptake and catabolism of 3¢-and 6¢-GL remain to be elucidated. In this study, we used differential transcriptomics to identify the utilization pathways of these GLs within the Bifidobacterium breve YIT 4014 T strain. We found that the BBBR_RS 2305-2320 gene locus, which includes a solute-binding protein (SBP) of an ATP-binding cassette (ABC) transporter and bgalactosidase, were up-regulated during 3¢-and 6¢-GL utilization. The substrate specificities of these proteins were further investigated, revealing that b-galactosidase hydrolyzed both 3¢-GL and 6¢-GL efficiently. Our surface plasmon resonance results indicated that the SBP bound strongly to 6¢-GL, but bound less tightly to 3¢-GL. Therefore, we looked for the other SBPs for 3¢-GL and found that the BBBR_RS08090 SBP may participate in 3¢-GL transportation. We also investigated the distribution of these genes in 17 bifidobacterial strains, including 9 B. breve strains, and found that the b-galactosidase genes were present in most bifidobacteria. Homologues of two ABC transporter SBP genes were found in all B. breve strains and in some bifidobacteria that are commonly present in the human gut microbiota. These results provide insights into the ability of human-resident bifidobacteria to utilize the main component of GOS in the gastrointestinal tract.

The galacto-oligosaccharide (GOS) OLIGOMATE 55N (Yakult) is a mixture of oligosaccharides, the main component of which is 4′-galactosyllactose (4′-GL). Numerous reports have shown that GOSs are non-digestible, reach the colon and selectively stimulate the growth of bifidobacteria. The product has been used as a food ingredient and its applications have expanded rapidly. However, the bifidobacterial glycoside hydrolases and transporters responsible for utilizing GOSs have not been characterized sufficiently. In this study, we aimed to identify and characterize genes responsible for metabolizing 4′-GL in Bifidobacterium breve strain Yakult. We attempted to identify B. breve Yakult genes induced by 4′-GL using transcriptional profiling during growth in basal medium containing 4′-GL with a custom microarray. We found that BbrY_0420, which encodes solute-binding protein (SBP), and BbrY_0422, which encodes β-galactosidase, were markedly upregulated relative to that during growth in basal medium containing lactose. Investigation of the substrate specificity of recombinant BbrY_0420 protein using surface plasmon resonance showed that BbrY_0420 protein bound to 4′-GL, but not to 3′-GL and 6′-GL, structural isomers of 4′-GL. Additionally, BbrY_0420 had a strong affinity for 4-galactobiose (4-GB), suggesting that this SBP recognized the non-reducing terminal structure of 4′-GL. Incubation of purified recombinant BbrY_0422 protein with 4′-GL, 3′-GL, 6′-GL and 4-GB revealed that the protein efficiently hydrolysed 4′-GL and 4-GB, but did not digest 3′-GL, 6′-GL or lactose, suggesting that BbrY_0422 digested the bond within Gal1,4-β-Gal. Thus, BbrY_0420 (SBP) and BbrY_0422 (β-galactosidase) had identical, strict substrate specificity, suggesting that they were coupled by co-induction to facilitate the transportation and hydrolysis of 4′-GL.

The meiosis-specific mug28+ gene of Schizosaccharomyces pombe encodes a putative RNA-binding protein. mug28Δ cells generated spores with low viability, due to the aberrant FSM formation. Meu14-GFP in mug28Δ cells showed that the FSM formed extra membranes with buds. We conclude that Mug28 is essential for the proper maturation of the FSM and the spore wall.