Seasonal regulations of energetics, serum concentrations of leptin, and uncoupling protein 1 content of brown adipose tissue in root voles (Microtus oeconomus) from the Qinghai-Tibetan plateau

Survival of small mammals in winter requires proper adjustments in physiology, behavior and morphology. The present study was designed to examine the changes in serum leptin concentration and the molecular basis of thermogenesis in seasonally acclimatized root voles (Microtus oeconomus) from the Qinghai-Tibetan plateau. In January root voles had lower body mass and body fat mass coupled with higher nonshivering thermogenesis (NST) capacity. Consistently, cytochrome c oxidase activity and mitochondrial uncoupling protein-1 (UCP1) protein contents in brown adipose tissues were higher in January as compared to that in July. Circulating level of serum leptin was significantly lower in winter and higher in July. Correlation analysis showed that serum leptin levels were positively related with body mass and body fat mass while negatively correlated with UCP1 protein contents. Together, these data provided further evidence for our previous findings that root voles from the Qinghai-Tibetan plateau mainly depend on higher NST coupled with lower body mass to enhance winter survival. Further, fat deposition was significantly mobilized in cold winter and leptin was potentially involved in the regulation of body mass and thermogenesis in root voles. Serum leptin might act as a starvation signal in winter and satiety signal in summer.

Effect of long-term grazing on soil organic carbon content in semiarid steppes in Inner Mongolia

To clarify the response of soil organic carbon (SOC) content to season-long grazing in the semiarid typical steppes of Inner Mongolia, we examined the aboveground biomass and SOC in both grazing (G-site) and no grazing (NG-site) sites in two typical steppes dominated by Leymus chinensis and Stipa grandis, as well as one seriously degraded L. chinensis grassland dominated by Artemisia frigida. The NG-sites had been fenced for 20 years in L. chinensis and S. grandis grasslands and for 10 years in A. frigida grassland. Above-ground biomass at G-sites was 21-35% of that at NG-sites in L. chinensis and S. grandis grasslands. The SOC, however, showed no significant difference between G-site and NG-site in both grasslands. In the NG-sites, aboveground biomass was significantly lower in A. frigida grassland than in the other two grasslands. The SOC in A. frigida grassland was about 70% of that in L. chinensis grassland. In A. frigida grassland, aboveground biomass in the G-site was 68-82% of that in the NG-site, whereas SOC was significantly lower in the G-site than in the NG-site. Grazing elevated the surface soil pH in L. chinensis and A. frigida communities. A spatial heterogeneity in SOC and pH in the topsoil was not detected the G-site within the minimal sampling distance of 10 m. The results suggested that compensatory growth may account for the relative stability of SOC in G-sites in typical steppes. The SOC was sensitive to heavy grazing and difficult to recover after a significant decline caused by overgrazing in semiarid steppes.

Post-grafting preparation of large-pore mesoporous materials with localized high content titanium doping

A new post-grafting process, consisting of two steps of substrate preparation and sol - gel post-grafting, has been developed to prepare titanium-doped mesoporous SBA-15 material with a double-layered structure and locally concentrated titanium content at the inner pore surface. With this novel technique, the single phased and originally ordered mesostructures can be well conserved; in the conventional direct synthesis they can be partially damaged when the frameworks are doped with high content heteroatoms. Titanium species exist in an isolated, tetrahedral structure and are localized at the pore surface; this is beneficial to both reactant access and product release. Characterization with XRD, N-2 adsorption/desorption isotherms, HREM/ EDS, ICP, UV - Vis, and the newly developed UV - Raman spectroscopy confirm these results. Preliminary catalytic tests with the selective epoxidation of cyclohexene show good catalytic activity. Among them, sample TiSBA-15-10 with a Si : Ti molar ratio of 10 shows a TON value of 75 and a highest product ( epoxide) yield of 55%.