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As a region with one of the most important terrestrial ecosystems, the Tibetan plateau is both sensitive to and vulnerable to climate warming. Locusta migratoria tibetensis Chen, an endemic species on the Tibetan plateau, is likely to be affected by climatic warming. In our studies, accumulated degree-days (ADD) of L. Migratoria T.C. were calculated based on data from 90 weather stations over the Tibetan plateau from 1961 to 2005. Trend lines show that across weather stations, ADD increased at a rate of 1.17 DD/a during climate warming. The majority of weather stations (82.2%) showing increases in ADD were located towards the west of the Tibetan plateau. At higher elevations, the increase in the ratio of annual ADD to the station mean ADD was higher relative to those at lower elevations. A linear regression model between ADD and geographical position was established to create raster maps of ADD in ArcGIS 9.2. The area of potential locust distribution (APD) was estimated to be 42 420 km2, mostly distributed along major rivers on the Tibetan plateau. In warmer years, the APD increased sharply over study periods. A new area of potential distribution would appear in the north Tibetan plateau if the climate warming continued. In the south-east Tibetan plateau, the locust would expand its range northwards or westwards along the river valleys, and the locust APD would also rise in elevation. [ABSTRACT FROM AUTHOR]

Mitochondria are crucial to the hypoxia response of aerobic organisms. However, mitochondrial mechanisms for hypoxia adaptation remain largely unknown. We conducted a comparative study on the mitochondrial hypoxia response and adaptation of the Tibetan Plateau and North China lowland populations of migratory locusts, Locusta migratoria. Compared with lowland locusts, Tibetan locusts presented significantly higher hypoxia tolerance and a better-maintained mitochondrial structure in flight muscles under oxygen partial pressure of 1.6 kPa. The hypoxic treatment inhibited the NADH-linked oxidative phosphorylation (OXPHOS) significantly in both locust populations, but to a less extent in Tibetan locusts. Among the critical components of OXPHOS, only cytochrome c oxidase (COX) exhibited significantly higher activity in Tibetan locusts under normoxia and hypoxia. Pharmacological interventions using NaN3 confirmed that COX activity inhibition reduced hypoxia tolerance by downregulating OXPHOS in both locust populations. The enhanced COX activity was caused not by protein content, but by elevated catalytic efficiency resulting from the increased ferrocytochrome c affinity of COX and the increased electron transport rate via catalytic redox centres. These findings reveal a novel mechanism that confers mitochondrial robustness against hypoxia by modulating the COX activity, which represents an adaptation to permanent hypoxia in the Tibetan Plateau. [ABSTRACT FROM AUTHOR]