No abstract

The effects of the anti-methanogenic compound, bromochloromethane (BCM), on rumen microbial fermentation and ecology were examined in vivo. Japanese goats were fed a diet of 50 % Timothy grass and 50 % concentrate and then sequentially adapted to low, mid and high doses of BCM. The goats were placed into the respiration chambers for analysis of rumen microbial function and methane and H 2 production. The levels of methane production were reduced by 5, 71 and 91 %, and H 2 production was estimated at 545, 2941 and 3496 mmol/head per d, in response to low, mid and high doses of BCM, respectively, with no effect on maintenance feed intake and digestibility. Real-time PCR quantification of microbial groups showed a significant decrease relative to controls in abundance of methanogens and rumen fungi, whereas there were increases in Prevotella spp. and Fibrobacter succinogenes, a decrease in Ruminococcus albus and R. flavefaciens was unchanged. The numbers of protozoa were also unaffected. Denaturing gradient gel electrophoresis and quantitative PCR analysis revealed that several Prevotella spp. were the bacteria that increased most in response to BCM treatment. It is concluded that the methane-inhibited rumen adapts to high hydrogen levels by shifting fermentation to propionate via Prevotella spp., but the majority of metabolic hydrogen is expelled as H 2 gas.Key words: Rumen: Methane: Hydrogen: Bromochloromethane: Goats Enteric fermentation in livestock accounts for 19 % of anthropogenic sources of methane, a potent greenhouse gas (1) , for which rumen fermentation is the largest source of methane production. In rumen fermentation, several pathways involving both hydrogen-producing and -consuming steps are involved in the conversion of feedstuffs into various fermentation end products such as SCFA (2,3) . Although metabolic hydrogen in the rumen is incorporated in fermentation end products by bacteria, methanogenic archaea (methanogens) consume the greater majority of metabolic hydrogen to obtain energy for their metabolism and finally release methane, which accounts for 2 -12 % loss of the metabolic energy from feed (1,3,4) . Therefore, management of metabolic hydrogen and methane production in the rumen is an important factor to be considered, when developing strategies to reduce greenhouse gas emissions and improve efficiency of energy utilisation from feed.It is known that many chemical agents such as ionophores (e.g. monensin), unsaturated fatty acids, sulphate, nitrate, fumarate and halogenated methane analogues (e.g. bromochloromethane (BCM)) are able to reduce methane production from ruminants (1,4 -6) . BCM is one of the most effective inhibitors and apparently reduces methane production by interfering with the cobamide-dependent methyl transferase step of methanogenesis (7,8) . BCM complexed in cyclodextrin (CD; BCM-CD) results in the sustained inhibition of methane production when fed to ruminants (9 -11) . Moreover, an in vitro continuous fermentation system simulating rumen fermentation demon...

Mammalian forkhead members of the class O (FOXO) transcription factors, including FOXO1, FOXO3a, and FOXO4, are implicated in the regulation of a variety of cellular processes, including the cell cycle, apoptosis, DNA repair, stress resistance, and metabolism. FOXO proteins are negatively regulated by the phosphatidylinositol 3-kinase-Akt signaling pathway, which is activated by growth factors and cytokines. Recent studies indicate that the activities of FOXO proteins are also regulated by oxidative stress, which induces their phosphorylation, translocation to the nucleus, and acetylation-deacetylation. Similar to the tumor suppressor p53, FOXO is activated by stress and induces the expression of genes that contribute to cell-cycle arrest, suggesting that it also functions as a tumor suppressor.

Studies on the ability of multicellular organisms to tolerate specific environmental extremes are relatively rare compared to those of unicellular microorganisms in extreme environments. Tardigrades are extremotolerant animals that can enter an ametabolic dry state called anhydrobiosis and have high tolerance to a variety of extreme environmental conditions, particularly while in anhydrobiosis. Although tardigrades have been expected to be a potential model animal for astrobiological studies due to their excellent anhydrobiotic and extremotolerant abilities, few studies of tolerance with cultured tardigrades have been reported, possibly due to the absence of a model species that can be easily maintained under rearing conditions. We report the successful rearing of the herbivorous tardigrade, Ramazzottius varieornatus, by supplying the green alga Chlorella vulgaris as food. The life span was 35 +/- 16.4 d, deposited eggs required 5.7 +/- 1.1 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90 degrees C and -196 degrees C, and exposure to 99.8% acetonitrile or irradiation with 4000 Gy (4)He ions. Based on their life history traits and tolerance to extreme stresses, R. varieornatus may be a suitable model for astrobiological studies of multicellular organisms.