Functional characterization of a novel, highly expressed ion-driven sugar antiporter in the thoracic muscles of Helicoverpa armigera.

Sugar transporters (STs), which mainly mediate cellular sugar exchanges, play critical physiological roles in living organisms, and they may be responsible for sugar exchanges among various insect tissues. However, the molecular and physiological functions of insect STs are largely unknown. Here, 16 STs of Helicoverpa armigera were identified. A phylogenetic analysis classified the putative HaSTs into 12 sub-families, and those identified in this study were distributed into 6 sub-families. Real-time polymerase chain reaction indicated that the 16 HaSTs had diverse tissue-specific expression levels. One transporter, HaST10, was highly expressed in thoracic muscles. A functional study using a Xenopus oocyte expression system revealed that HaST10 mediated both H+ -driven trehalose and Na+ -driven glucose antiport activities with high transport efficiency and low affinity levels. A HaST10 knockout clearly impaired the performance of H. armigera. Thus, HaST10 may participate in sugar-supply regulation and have essential physiological roles in H. armigera.

[Forest soil organic carbon density and its distribution characteristics along an altitudinal gradient in Lushan Mountains of China].

To understand the spatial distribution characteristics of organic carbon in northern subtropical forest soils along an altitudinal gradient in Lushan Mountains of China, six and five sampling plots with a 200-m interval of elevation and covered by different vegetation types were installed on the southern and northern slopes, respectively in July-August in 2010 to collect soil profiles, with the soil thickness, bulk density, organic carbon content, and organic carbon density of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and >40 cm layers measured. The soil organic carbon density was significantly affected by altitude and slope. On northern slope, soil organic carbon content increased with increasing altitude, and had significant negative correlations with soil bulk density and pH value. On southern slope, soil organic carbon content had no obvious variation pattern along the altitudinal gradient and had less correlation with soil bulk density and pH value, but soil organic carbon density decreased with increasing soil depth. The soil organic carbon density on northern and southern slopes was within the range of 7.07 - 10. 34 kg x m(-2) and 6.03 - 12.89 kg x m(-2), respectively. The larger variation of soil organic carbon density along altitudinal gradient and soil depth on southern slope suggested that the destruction of original vegetation and the establishment of forest plantation could be one of the important factors affecting the spatial distribution of soil organic carbon.