Primary Studies On Physiological Mechanisms Of Temperature And Salinity Resistance Of An Intertidal Limpet Cellana Toreuma

The intertidal ecosystem is one of the most threatened ecosystems in the scenario of global change. Variation in physical environmental conditions plays an important role in regulating the distribution and abundance of natural population. Such stressors can cause heavy mortality and limit the distribution of species when extreme events occur, particularly high temperature, are commonly invoked to explain the upper distribution of rocky intertidal species. In tropical monsoonal areas, intertidal animals can face hot desiccation conditions during emersion preceded, or followed by, intense rainfall, then the physical stress on such shores is likely to be a combination of exposure to rainfall and heat stress, a combination of exposure to desiccation and heat stress. The multiple environmental factors change can influence biological behavior, physiological and evolutionary adaptation, and then change the population dynamics and community structure. Physiological adaptation is one of the main response options for organisms facing environmental change. Intertidal limpets(Cellana toreuma) provide an excellent study system for examining this type of interspecific variation in sensitivity to environmental change.The research on physiological parameters and molecular markers changes should be very useful for elucidating physiogical responses and mechanism adaptation during environmental stresses and is to clearly know the environmental stresses impact on species’ dynamics underlying physiological mechnisms. The principal results include:(1) High temperature can lead to the accumulation of protein carbonyl groups, and significantly increased the protein oxidative damage. The process was energy-consumptive.(2) All the physiological parameters were sensitive to temperature and duration of heat stress and were energy-consumptive, as indicated by the upregulation of metabolic sensors mRNA. The significant increase of protein carbonyl groups at34℃after4h exposure indicated that the increase of anaerobic metabolism lead to the accumulation of protein carbonyl groups. When the temperature returned to16℃for12h, the overall physiological performance returned to the level before heat stress, indicating that the physiological adaptation of this species was rapid and effective at the transcriptional level.(3) Low salinity would be a variety of physiological as well as biochemical changes, When returned to seawater for12h, the overall physiological performance returned to the level before heat stress, indicating that the physiological adaptation of this species was rapid and effective at the transcriptional level. Although freshwater posed potential threat to the survival of limpets, it would not be the key factor responsible for high mortality.(4) Through the change of HSPs encoding gene and energy metabolism factor, a combination of temperature and desiccation posed a grave threat to the survival of limpets. Double stimulation of both temperature and desiccation resulted in the change of physiological, the degree of third stimulation was significant.(5) The whole transcriptome of C. toreuma under sublethal stress was examined using the454sequencing technology.(6) The upregualtion of genes were concentrate in energy metabolism, protein folding, cytoskeletal structure etc. The upregulation of alanopine dehydrogenase indicated that metabolism thus switched to anaerobiosis to compensate for insufficient aerobic energy supply for the progressive increasing costs in maintenance, and the process of anaerobiosis was opine-producing pathway, Most importantly, hypoxic activation of HIF-1promotes ATP production through increased anaerobic glycolysis.(7) The up-regulation of collagen could reduce growth, more energy would be allocated to fuel stress responses. The decrease of cdo indicated the growth might be inhibition(8) BIRC3are necessary for promoting cell survival through to be a direct inhibitor of apoptotic proteases called Caspases. which could be one of reasons why C. toreuma still be alive a long time in condition of ambient temperature above ABT, namely enhanced cellular survival near ABT. We testified that our gene expression data were reliable through the experimental validation of14randomly selected genes using real time PCR, providing good reference to studies on molecular mechanism during sublethal stess of limpets in the intertidal zone.In the context of climate warming, many intertidal individuals may suffer frequent and extreme thermal stress in summer, and may be living very close to their thermal limit for survival and reproduction. Limpets in the subtropical rocky shore will have to invest more energy for maintenance, which should result in less energy being available for growth and reproduction, placing a constraint on ecological fitness and affecting population dynamics.