Influence of temperature on glutathione level and glutathione-related enzyme activities of Antarctic ice microalgae Chlamydomonas sp.ICE-L

GSH system plays a role in the control of the redox balance state, anti-oxidation and protecting life from injury of ROS （ reactive oxygen species）. In present paper, the possible GSH system of Chlamydomonas sp. ICE-L has been investigated by evaluating GSH and GSH-related enzymatic responses at different temperatures using spectrophotometer methods. The results showed that the GSH system is correlated positively to low temperature, and other factors but GR are correlated negatively to high temperature. So GSH and GSH-related enzymes play an important role in the adaptation of Antarctic ice microalgae to low temperature.

An Effective Method of Prompting Juvenile Rainbow Trout (Oncorhynchus mykiss) to Cope with Heat Stress

In the present study,juvenile rainbow trout(Oncorhynchus mykiss)were acclimated at 5 temperatures.Fish in the control group(C0)were reared at a constant temperature(16℃);trout in four other treatments(A0,A3,A6,and A9)were acclimated to a high temperature(22℃)for 0,3,6,and 9 d,respectively,and then returned to normal temperature(16℃)for 7d.The temperature was then raised to 20℃and the fish were cultured for 40 d.The results showed that the growth rates of A3,A6,and A9 were higher than that of A0 but lower than that of C0.The growth rate of A9 was the highest among the 4 acclimation groups.The activities of serum transaminase and liver antioxidant enzyme significantly increased during acclimation.At the beginning of growth,the activities of enzymes were lower in A3,A6,and A9 with the lowest in A9.In addition,the transcript abundance of heat shock protein(HSP)60 gene in A9 was not significantly different from that of C0 during growth.HSP70 in A9 significantly increased at the beginning and returned to that of C0 at the end.Our findings indicated that pre-acclimation improved the high temperature tolerance with the best effectiveness observed at 22℃for 9 d.A possible mechanism underlining such phenomenon is the improvement of antioxidant defense system.

Characteristics of pellets with immobilized activated sludge and its performance in increasing nitrification in sequencing batch reactors at low temperatures

Immobilized pellets obtained by means of entrapping activated sludge in waterborne polyurethane were successfully adapted in ammonium（NH4^＋–N）synthetic wastewater.Its physicochemical characteristics were determined using scanning electron microscope,pyrosequencing,and microelectrodes,and its influence on the nitrification process in sequencing batch reactors（SBRs）at low temperatures was evaluated.A large number of rod-shaped bacteria were observed on the surface of the immobilized pellet,in which Rudaea spp.（Xanthomonadaceae family）was an important bacterial component（23.44% of the total bacteria）.The oxygen uptake rate of immobilized pellets reached 240.83±15.59 mg O2/（L·hr）,and the oxygen was primarily consumed by the bacteria on the pellet surfaces（0–600μm）.The dosing of the pellets（30 m L/L）into an SBR significantly improved the nitrification efficiency at low temperatures of 7–11℃,achieving an average NH4^＋–N removal of 84.09%,which is higher than the removal of 67.46% observed for the control group.

Grazing alters warming effects on leaf photosynthesis and respiration in Gentiana straminea,an alpine forb species

Aims Vast grasslands on the Tibetan Plateau are almost all under livestock grazing.It is unclear,however,what is the role that the grazing will play in carbon cycle of the grassland under future climate warming.We found in our previous study that experimental warming can shift the optimum temperature of saturated photosynthetic rate into higher temperature in alpine plants.In this study,we proposed and tested the hypothesis that livestock grazing would alter the warming effect on photosynthetic and respiration through changing physical environments of grassland plants.Methods Experimental warming was carried by using an infrared heating system to increase the air temperature by 1.2 and 1.7℃ during the day and night,respectively.The warming and ambient temperature treatments were crossed over to the two grazing treatments,grazing and un-grazed treatments,respectively.To assess the effects of grazing and warming,we examined photosynthesis,dark respiration,maximum rates of the photosynthetic electron transport(J_(max)),RuBP carboxylation(V_(cmax))and temperature sensitivity of respiration Q_(10) in Gentiana straminea,an alpine species widely distributed on the Tibetan grassland.Leaf morphological and chemical properties were also examined to understand the physiological responses.Important findings 1)Light-saturated photosynthetic rate(A_(max))of G.straminea showed similar temperature optimum at around 16℃ in plants from all experimental conditions.Experimental warming increased A_(max) at all measuring temperatures from 10 to 25℃,but the positive effect of the warming occurred only in plants grown under the un-grazed conditions.Under the same measuring temperature,A_(max) was significantly higher in plants from the grazed than the un-grazed condition.2)There was significant crossing effect of warming and grazing on the temperature sensitivity(Q_(10))of leaf dark respiration.Under the un-grazed condition,plants from the warming treatment showed lower respiration rate but similar Q_(10) in comparison with plants from the ambient temperature treatment.However,under the grazed condition Q_(10) was significantly lower in plants from the warming than the ambient treatment.3)The results indicate that livestock grazing can alter the warming effects on leaf photosynthesis and temperature sensitivity of leaf dark respiration through changing physical environment of the grassland plants.The study suggests for the first time that grazing effects should be taken into account in predicting global warming effects on photosynthesis and respiration of plants in those grasslands with livestock grazing.