Stygiopontius senokuchiae is a hydrothermal-vent-specific copepod species (Dirivultidae, Siphonostomatoida) and abundantly distributes near vent orifices. This species is thought to have an early juvenile planktic stage, and previous studies using bulk tissue stable-isotope and radioisotope data suggest that adults ingest chemoautotrophic microbes growing on vent chimneys. However, ontogenetic changes in their diets have not been investigated. We analysed gut contents of copepodite I to adult stages of S. senokuchiae collected from a hydrothermal-vent chimney at the Izu-Ogasawara Arc to check for the presence of bacterial cells in oral tubes and guts. We compared these results with an unidentified co-occurring calanoid and a species of Ectinosoma (Harpacticoida) and to other Siphonostomatoid copepods, namely Hatschekia labracis (Hatschekiidae), which was attached to a scarbreast tuskfin (Choerodon azurio, Labridae), and Asterocheres sp. 1 (Asterocheridae), which was attached to a spirastrellid sponge. Carbon isotope ratios of S. senokuchiae at different stages and Ectinosoma were measured to complement the nutritional insights obtained from gut-content analysis. Our results clearly showed that most S. senokuchiae individuals possessed bacteria in the oral tube or gut regardless of growth stage, whereas the coexisting Ectinosoma and calanoid did not. The carbon isotopic compositions confirmed that S. senokuchiae gains its nutrition from chemoautotrophic bacteria that use the rTCA carbon-fixation pathway. Comparisons with other Siphonostomatoida copepods suggest that Dirivultidae are specifically adapted to feed on bacteria at hydrothermal-vent chimneys, allowing their high dominance and evolutionary success in these habitats.

Probiotic Lactobacillus gasseri SBT2055 (LG2055) reduces postprandial TAG absorption and exerts anti-obesity effects in rats and humans; however, the underlying mechanisms are not fully understood. In the present study, we addressed the mechanistic insights of the anti-obesity activity of LG2055 by feeding Sprague–Dawley rats diets containing skimmed milk fermented or not by LG2055 for 4 weeks and by analysing energy expenditure, glucose tolerance, the levels of SCFA in the caecum and serum inflammatory markers. Rats fed the LG2055-containing diet demonstrated significantly higher carbohydrate oxidation in the dark cycle (active phase for rats) compared with the control group, which resulted in a significant increase in energy expenditure. LG2055 significantly reduced cumulative blood glucose levels (AUC) compared with the control diet after 3 weeks and increased the molar ratio of butyrate:total SCFA in the caecum after 4 weeks. Furthermore, the LG2055-supplemented diet significantly reduced the levels of serum amyloid P component – an indicator of the inflammatory process. In conclusion, our results demonstrate that, in addition to the inhibition of dietary TAG absorption reported previously, the intake of probiotic LG2055 enhanced energy expenditure via carbohydrate oxidation, improved glucose tolerance and attenuated inflammation, suggesting multiple additive and/or synergistic actions underlying the anti-obesity effects exerted by LG2055.

The probiotic Lactobacillus gasseri SBT2055 (LG2055) has anti-obesity effects. Obesity is closely correlated with inflammation in adipose tissue, and maintaining adipose tissue in a less-inflamed state requires intestinal integrity or a barrier function to protect the intestine from the disruption that can be caused by a high-fat diet (HFD). Here, we examined the anti-inflammatory and intestinal barrier-protecting effects of LG2055 in C57BL/6 mice fed a normal-fat diet (NFD), HFD, or the HFD containing LG2055 (HFD-LG) for 21 weeks. HFD-LG intake significantly prevented HFD-induced increases in body weight, visceral fat mass, and the ratio of inflammatory-type macrophages to anti-inflammatory ones in adipose tissue. Mice fed the HFD showed higher intestinal permeability to a fluorescent dextran administered by oral administration and an elevated concentration of antibodies specific to lipopolysaccharides (LPS) in the blood compared with those fed the NFD, suggesting an increased penetration of the gut contents into the systemic circulation. These elevations of intestinal permeability and anti-LPS antibody levels were significantly suppressed in mice fed the HFD-LG. Moreover, treatment with LG2055 cells suppressed an increase in the cytokine-induced permeability of Caco-2 cell monolayers. These results suggest that LG2055 improves the intestinal integrity, reducing the entry of inflammatory substances like LPS from the intestine, which may lead to decreased inflammation in adipose tissue.

Consumption of fermented milk (FM) containing a probiotic, Lactobacillus gasseri SBT2055 (LG2055), previously showed a reduction in abdominal adiposity in a randomised controlled trial (RCT) using FM with 108 colony-forming units (cfu) of LG2055/g. However, whether the effectiveness is observed at lower concentrations, the recommended minimum or intermediate levels of probiotics (106 or 107cfu/g, respectively), remains to be examined. A multi-centre, double-blind, parallel-group RCT was conducted using 210 healthy Japanese adults with large visceral fat areas (80·2–187·8 cm2). They were balanced for their baseline characteristics and randomly assigned to three groups receiving FM containing 107, 106 or 0 (control) cfu LG2055/g of FM, and were asked to consume 200 g FM/d for 12 weeks. Abdominal visceral fat areas, which were determined by computed tomography, at week 12, changed from baseline by an average of − 8·5 % (95 % CI − 11·9, − 5·1; P< 0·01) in the 107 dose group, and by − 8·2 % (95 % CI − 10·8, − 5·7; P< 0·01) in the 106 dose group. Other measures including BMI, waist and hip circumferences, and body fat mass were also significantly decreased from baseline at week 12 in both groups; interestingly, the cessation of taking FM for 4 weeks attenuated these effects. In the control group, none of these parameters significantly decreased from baseline. These findings demonstrate that consumption of LG2055 at doses as low as the order of 108cfu/d exhibited a significant lowering effect on abdominal adiposity, and suggest that constant consumption might be needed to maintain the effect.

High-resolution angle resolved ultraviolet photoelectron spectroscopy measurements were conducted on rubrene single crystals successfully through relief of the sample charging assisted by a laser illumination. Significant dispersion of the valence band was clearly resolved. The band width W and the hole effective mass mh* were estimated to be 0.4 eV and 0.7m0, respectively, along the most conductive direction. The present results strongly suggest that the transport nature in rubrene single crystals should be described in the band transport framework of a delocalized charge carrier.