No abstract

Limited information is available about how mammalian browsing activity influences the dynamic defense mechanisms of plants. Here, we aimed to clarify the response mechanism of a herbaceous plant (Chinese lyme grass, Leymus chinensis) to browsing by a mammalian herbivore (Brandt's vole, Lasiopodomy brandtii). We used high-performance liquid chromatography and spectrophotometry to investigate changes in the concentrations of 6-MBOA, total phenol and condensed tannin in Chinese lyme grass seedlings with respect to its ontogeny and different types of damage treatments. 6-MBOA concentrations were higher on day 7 and day 8 than on days 12 and 17 after seedling germination. The concentrations of total phenol and condensed tannin were higher on day 12 than on days 7 and 8 after seedling germination. Compared to the control, higher 6-MBOA concentrations were obtained in the salivation, gnawing and artificial cutting treatment groups. The response of 6-MBOA was delayed in the artificial cutting group compared to the salivation and gnawing groups. In contrast, the concentrations of total phenol and condensed tannin were higher in the artificial cutting and control groups compared to the salivation and gnawing groups. 6-MBOA concentration was negatively correlated with total phenol concentration. The results indicated that 6-MBOA concentration decreased with seedling ontogeny, and that it could be induced by Brandt's vole saliva. In conclusion, our study verified the hypothesis that the browsing by Brandt's vole induces the dynamic defenses of L. chinensis.

No abstract

The effect of extrusion treatment on the mechanical, thermal and corrosion resistance of Mg–La–Zn–Zr alloys were presented. It is suggested that the amount of recrystallized grains played a major role in both mechanical properties and thermal properties. It should be noted the as-cast alloy shows the best thermal conductivity reached the value about 137.507 W/(m · K), however, the mechanical performance of magnesium alloys does not reach the expected results. The thermal properties of extruded alloys have slightly decreased and then increased with the increase of extrusion temperature. Then the tensile properties of Mg–La–Zn–Zr were significantly improved after extrusion treatment. Furthermore, with the increase of extrusion temperature, the elongation-to-fracture increased substantially. After extrusion treatment, the corrosion driving force of the alloy decreases, which reduces the corrosion tendency of the magnesium alloy. The alloy presented in this paper is expected to be applied in industry.

Tannins, which are polyphenols present in various plants, have anti-nutritional activity; however, their negative effects are mitigated by the presence of tannin-degrading microorganisms in the gastrointestinal tract of animals. This has never been investigated in the plateau zokor (Myospalax baileyi) À the predominant small herbivore in the alpine meadow ecosystem of Qinghai Province, China À which consumes tannin-rich herbaceous plants. Tannase activity in the feces of the plateau zokor increased from June to August corresponding to the increase in hydrolyzable tannin concentrations in plants during this period, and three tannin-degrading facultative anaerobic strains (designated as E1, E2, and E3) were isolated from the cecum of these animals. Sequencing of the 16S rDNA gene identified isolates of strain E1 as belonging to the genus Enterococcus, and E2 and E3 to the genus Bacillus. All of the bacteria had cellulose-degrading capacity. This study provides the first evidence of symbiotic bacterial strains that degrade tannic acid and cellulose in the cecum of plateau zokor.