Studies On Life History And The Expression Of Heat Shock Protein Of Rotaria Rotatoria

The Bdelloid rotifer,an important components of freshwater zooplankton,is the largest Metazoan group reproduced only in parthenogenesis.The higher potentially genetic diversity known up to now is that of bdelloid species,with their worldwide distribution and distinct lineage differentiation of traditional species.Using the individual culture method,we compared the responses of life table parameters to increasing temperature among the three rotifer evolving entities,and then explored the expression regulation of HSP70 in rotifers exposed to high temperature.The main contents and results were presented as following:1.Three clones(HX4,HX8 and HX19)of Bdelloidea Rotaria rotatoria were selected to be the representatives of three sympatric putative cryptic taxa for detecting the effects of temperature(24,28 and 32?)on their life history traits.The results showed that the responses of life table parameters to increasing temperature were different among the three rotifer evolving entities.Evolutionary species,temperatures,and their interaction significantly affected the all life history parameters except that evolutionary species did not significantly affect the durations of post-reproductive period(PP)and mean lifespan(ML),as well as the interaction of evolutionary species and temperatures did not significantly affect the durations of post-reproductive period(PP),offspring production(OP)and net reproductive rate(R0),respectively.Temperature significantly affected all the life history parameters unexceptionally.For the clone HX4,the durations of juvenile period(JP),reproductive period(RP),post-reproductive period(PP),mean lifespan(ML),offspring production(OP),life expectancy at hatching(e0)and generation time(GT)significantly shortened or decreased with increasing temperature.On the contrary,its intrinsic rate of population growth(rm)increased with increasing temperature.For HX8,the durations of juvenile period(JP),reproductive period(RP),post-reproductive period(PP),mean lifespan(ML),life expectancy at hatching(e0)and generation time(GT)were the longest at24?,while the intrinsic rate of population growth(rm)and age-specific fecundity(mx)were the smallest.As far as the clone HX19 was concerned,the duration of post-reproductive period(PP),mean lifespan(ML)and life expectancy at hatching(e0)significantly shortened with increasing temperature,while there were no significant difference in net reproductive rate(R0),generation time(GT)and age-specific fecundity(mx)among three temperatures.No matter what the evolutionary species was,the age-specific survival curves tended to decrease earlier and more quickly with the increasing of temperature.The age-specific survival curve of HX8 at 24? decreased most slowly and that of HX4 at32? decreased most fast.And the peak of age-specific fecundity curves appeared earlier with the increasing of temperature.No matter what the evolutionary species was,the peak appeared earliest at 32? and latest at 24?.The three potential cryptic R.rotatoria taxa adopted variable life history strategies,low reproduction and high survivorship at low temperature as well as high reproduction and low survivorship at high temperature.The similar adaptation abilities of the HX4,HX8 and HX19 to water temperatures could be the best explanation for their coexistence in the subtropical shallow pond at a high temperature.2.The expression of HSP70 in rotifers under different stress conditions were detected using western blot technique and immunofluorescence staining method.(1)When rotifers were stressed at 40? for different time,the HSP70 increased markedly after a heat shock,and the expression level elevated with the increasing of stress time.(2)We detected HSP70 in rotifers under different temperatures and discovered that besides the high temperature(40?),low temperature(16?)could also induce the expression of HSP70.The expression level significantly increased compared to the control group.(3)The expression level of HSP70 in heat shock treated rotifers was investigated after different recovery time.After we removed the heat shock,expression level continue to rise for a period of time and reached the peak level in 12 h,then declined slowly.In summary,these results showed that the change of temperature could induce the expression of HSP70,and the expression level is correlated with the intensity of stimulation.High and low temperature stress can both promote the expression of HSP70,and they have the similar stress intensity for rotifers.HSP70 expression dynamics is rapid and transient.HSP70 increased markedly after a heatshock and reached the peak level in a short time,then declined slowly.HSP70 can help maintain the stability of cell structure and function and enhance the heat resisting ability of the rotifers.In the face of unstable living environment,such as temperature fluctuation,rotifers could adapt to it by adjusting the expression of HSP70.