Effect of 3-nitrooxypropanol on methane and hydrogen emissions, methane isotopic signature, and ruminal fermentation in dairy cows.

The objective of this crossover experiment was to investigate the effect of a methane inhibitor, 3-nitrooxypropanol (3NOP), on enteric methane emission, methane isotopic composition, and rumen fermentation and microbial profile in lactating dairy cows. The experiment involved 6 ruminally cannulated late-lactation Holstein cows assigned to 2 treatments: control and 3NOP (60 mg/kg of feed dry matter). Compared with the control, 3NOP decreased methane emission by 31% and increased hydrogen emission from undetectable to 1.33 g/d. Methane emissions per kilogram of dry matter intake and milk yield were also decreased 34% by 3NOP. Milk production and composition were not affected by 3NOP, except milk fat concentration was increased compared with the control. Concentrations of total VFA and propionate in ruminal fluid were not affected by treatment, but acetate concentration tended to be lower and acetate-to-propionate ratio was lower for 3NOP compared with the control. The 3NOP decreased the molar proportion of acetate and increase those of propionate, butyrate, valerate, and isovalerate. Deuterium-to-hydrogen ratios of methane and the abundance of (13)CH3D were similar between treatments. Compared with the control, minor (4‰) depletion in the (13)C/(12)C ratio was observed for 3NOP. Genus composition of methanogenic archaea (Methanobrevibacter, Methanosphaera, and Methanomicrobium) was not affected by 3NOP, but the proportion of methanogens in the total cell counts tended to be decreased by 3NOP. Prevotella spp., the predominant bacterial genus in ruminal contents in this experiment, was also not affected by 3NOP. Compared with the control, Ruminococcus and Clostridium spp. were decreased and Butyrivibrio spp. was increased by 3NOP. This experiment demonstrated that a substantial inhibition of enteric methane emission by 3NOP in dairy cows was accompanied with increased hydrogen emission and decreased acetate-to-propionate ratio; however, neither an effect on rumen archaeal community composition nor a significant change in the isotope composition of methane was observed.

Effect of platelet-rich plasma therapy associated with exercise training in musculoskeletal healing in rats.

BACKGROUND: Muscle healing is a time-dependent process associated with an increase in the total amount of local collagen fibers. Platelet-rich plasma therapy (PRPT) associated with exercise may improve this healing process. The aim of this study was to demonstrate the regenerative effect of PRPT in association with exercise training on musculoskeletal healing. METHODS: Male Wistar rats were submitted to an injury in the vastus lateralis muscle and randomly divided into 4 groups (n = 5/group): sedentary sham-operated (SSO); sedentary group submitted to PRPT (SPR); swim-trained (SWT); and swim-trained group submitted to PRPT (SWP). Serum lactate level was used to confirm the training protocol effectiveness to increase aerobic fitness. The collagen fiber concentration was measured by the polarization colors in picrosirius red-stained tissue sections. RESULTS: Lactate levels decreased in both training groups (SWT and SWP; P < .05) after training (SWT: from 6.2 ± 0.44 to 4.7 ± 0.22 mmol/L; SWP: from 5.5 ± 0.99 to 4.0 ± 0.78 mmol/L). There were less type 1 collagen fibers in SWP group compared with other groups (SSO = 31.8 ± 10.3, SSP = 32.3 ± 13.5, SWT = 14.6 ± 13.4, SWP = 5.7 ± 4.7, P < .05), while there were more type 3 collagen fibers on SWP (SSO = 68.7 ± 9.8, SSP = 71.2 ± 12.2, SWT = 85.4 ± 13.4, SWP = 94.4 ± 4.6, P < .05) in the injured region. CONCLUSION: Exercise in association with PRPT enhances the skeletal muscle-healing process.

Virulence evolution in a host-parasite system in the absence of viral evolution.

QUESTION: How does virulence evolve in the Drosophila melanogaster/sigma virus (DMelSV) system? ORGANISMS: Drosophila melanogaster (host) and DMelSV (parasite). EMPIRICAL METHODS: Artificial selection on whole-carcass viral titre of infected flies, including two selection regimes (maternal and biparental transmission) and three treatments within each regime (increased titre, decreased titre, and control). The maternal transmission selection regime lasted for six generations, while the biparental transmission selection regime lasted for twelve generations. We further quantified virulence by estimating the fecundity, viability, and development time of infected flies. Finally, we sequenced virus strains at the end of selection. PREDICTIONS AND CONCLUSIONS: Titre is defined here as the number of viral genomes inside a single fly, while virulence is defined as harm to host. We predicted that titre would respond to both increased and decreased selection, that virulence would evolve as a positively correlated response, and that sequence evolution in the viruses would be responsible for these changes. Titre did respond to selection in the biparental regime, although both high and control lines both demonstrated increased titre, while the titre of the low lines did not change. One component of virulence, development time, was positively correlated with titre in the biparental transmission lines (maternal transmission lines were not scored for virulence). However, we detected few (and in some cases, no) genomic changes in the virus, making viral evolution unlikely to be responsible for the response to selection and the association between development time and titre.