Maternal exercise before and during pregnancy alleviates metabolic dysfunction associated with high-fat diet in pregnant mice, without significant changes in gut microbiota.

Although maternal exercise before and during pregnancy is beneficial, the effects of exercise on microbiota changes during pregnancy are unknown. Here we tested the hypothesis that maternal exercise before and during pregnancy would positively affect glucose homeostasis, pancreatic cell function, and gut microbiota dysbiosis in high-fat diet (HFD) fed dams. Female C57BL/6 mice were fed either a HFD or a low-fat diet (LFD) for 12 weeks. The HFD mice were split into two groups for 4 weeks prior to pregnancy initiation and throughout the pregnancy: sedentary (HFD) or exercised (HFD + Ex). Food intake, body weight, body composition, and glucose and insulin tolerance were measured. At gestation day 19, blood, pancreas, gonadal visceral and subcutaneous fat, plantaris muscle, and cecum were collected for analysis. Both HFD and HFD + Ex mice had impaired glucose clearance compared to LFD mice at 15 days of gestation. No changes were found in pancreatic α- or ß-cell health. HFD + Ex mice had significantly reduced visceral fat mass, serum insulin, and leptin levels and increased high-density lipoprotein levels, compared to HFD-fed mice. In contrast to our hypothesis, microbiota diversity and composition were not different among groups. The relative abundance of five bacterial phyla, such as Firmicutes, Bacteroidetes, Verrucomicrobia, Deferribacteres, and Actinobacteria, were not significantly altered with diet or exercise during pregnancy. Our findings suggest that maternal exercise prevents excess visceral fat accumulation, hyperinsulinemia, and hyperleptinemia associated with a HFD, but not through the alterations of gut microbiota composition or diversity during pregnancy.

A comparison of methods used to unveil the genetic and metabolic pool in the built environment.

BACKGROUND: A majority of indoor residential microbes originate from humans, pets, and outdoor air and are not adapted to the built environment (BE). Consequently, a large portion of the microbes identified by DNA-based methods are either dead or metabolically inactive. Although many exceptions have been noted, the ribosomal RNA fraction of the sample is more likely to represent either viable or metabolically active cells. We examined methodological variations in sample processing using a defined, mock BE microbial community to better understand the scope of technique-based vs. biological-based differences in both ribosomal transcript (rRNA) and gene (DNA) sequence community analysis. Based on in vitro tests, a protocol was adopted for the analysis of the genetic and metabolic pool (DNA vs. rRNA) of air and surface microbiomes within a residential setting. RESULTS: We observed differences in DNA/RNA co-extraction efficiency for individual microbes, but overall, a greater recovery of rRNA using FastPrep (> 50%). Samples stored with various preservation methods at - 80°C experienced a rapid decline in nucleic acid recovery starting within the first week, although post-extraction rRNA had no significant degradation when treated with RNAStable. We recommend that co-extraction samples be processed as quickly as possible after collection. The in vivo analysis revealed significant differences in the two components (genetic and metabolic pool) in terms of taxonomy, community structure, and microbial association networks. Rare taxa present in the genetic pool showed higher metabolic potential (RNA:DNA ratio), whereas commonly detected taxa of outdoor origins based on DNA sequencing, especially taxa of the Sphingomonadales order, were present in lower relative abundances in the viable community. CONCLUSIONS: Although methodological variations in sample preparations are high, large differences between the DNA and RNA fractions of the total microbial community demonstrate that direct examination of rRNA isolated from a residential BE microbiome has the potential to identify the more likely viable or active portion of the microbial community. In an environment that has primarily dead and metabolically inactive cells, we suggest that the rRNA fraction of BE samples is capable of providing a more ecologically relevant insight into the factors that drive indoor microbial community dynamics.

The time course of short-term hypertrophy in the absence of eccentric muscle damage.

BACKGROUND: It has been proposed that the increase in skeletal muscle mass observed during the initial weeks of initiating a resistance training program is concomitant with eccentric muscle damage and edema. PURPOSE: We examined the time course of muscle hypertrophy during 4 weeks of concentric-only resistance training. METHODS: Thirteen untrained men performed unilateral concentric-only dumbbell curls and shoulder presses twice per week for 4 weeks. Sets of 8-12 repetitions were performed to failure, and training loads were increased during each session. Subjects consumed 500 ml of whole milk during training. Assessments of soreness, lean mass, echo intensity, muscle thickness, relaxed and flexed arm circumference, and isokinetic strength were performed every 72 or 96 h. RESULTS: Soreness, echo intensity, relaxed circumference, and peak torque data did not significantly change. Significant increases in lean mass, muscle thickness, and flexed circumference were observed within seven training sessions. Lean mass was elevated at tests #7 (+109.3 g, p = .002) and #8 (+116.1 g, p = .035), with eight different subjects showing changes above the minimal difference of 139.1 g. Muscle thickness was elevated at tests #6 (+0.23 cm, p = .004), #7 (+0.31 cm, p < .001), and #8 (+0.27 cm, p < .001), with ten subjects exceeding the minimal difference of 0.24 cm. There were no changes for the control arm. CONCLUSION: In individuals beginning a resistance training program, small but detectable increases in hypertrophy may occur in the absence of eccentric muscle damage within seven training sessions.