| Abalone farming is an important part of aquaculture in China.Hybrid breeding is widely used as a common breeding method in the breeding of abalone,which has become a practical way to improve the biological characteristics of abalone.In this paper,the influences of both temperature mutation and gradually temperature change on the expression of hsp70 and the activities of several enzymes(SOD,AKP,LZM)were studied.The temperature was set at 4?,90?,14?,19?,24?,29?,the determination time is 0 h,2 h,6 h,12 h,24 h,48 h after stimulation.The main results are as follows:1.Influence of temperature shock on hsp70 expression of hybrid abaloneThe results showed that the expression of hsp70 of hybrid abalone is low at 14?and 19?,and there was no significant difference between the two groups(P>0.05).We estimated that the 14? and 19? were still in the appropriate growth range of hybridization.Starting from 14? and 19?,with the decrease or increase of the stimulating temperature,the hybridized abalone could resist the environmental change by up-regulating the expression of hsp70.The relative expression of hsp70 in the high temperature test group(24?,28?)showed a time-dependent expression,and a high relative expression level of hsp70 was maintained at 0 h-12 h,decreased at 24 h,then increased at 48 h.In 4?and 9? groups,the relative expression of hsp70 significantly increased at 24 h,which indicated that hybridization could increase hsp70 expression to resist low temperature abrupt stimulation,But the reaction process is slower.2.Influence of temperature mutation on the activities of several immune enzymesSOD:4? group was stable at all time points,which indicated that the influence of low temperature on the activity of SOD was not significant.Stating from 19?,with the increase of temperature or decrease,SOD activity increased,but reduced at 29?.After the sudden change of temperature,the activity of SOD increased in 12 h,and then decreased gradually.The difference between the temperature groups gradually decreased.AKP:Putting 14? as the temperature base,AKP activity increased with the temperature rise or decrease gradually,but the difference between the temperature group was not significant(P>0.05).After the sudden change of temperature,the AKP activity of hybrid abalone was decreased slightly,then increased,then decreased,and higher than 0 h at 48 h.The activity of AKP in 29? group reached the highest at 12 h,and the other groups reached the highest at 24 h.In addition,4? group and 29?,respectively,the phenomenon of AKP surge occurred,we speculated that at 4? or 29?,hybrid abalone can still adapt to the temperature change within a short period of time,but can not adapt to long-term high temperature or low temperature environment.Then hybrid abalone improve AKP activity to enhance resistance.LZM:LZM activity increased first and then decreased,then increased with the change of time.In the early stage of stimulation,great difference of LZM activity exist in different temperature groups.In addition,we also found that the activity of LZM in the 14? group was higher than that in other temperature groups,which was consistent with the previous studies.The LZM activity was higher at the appropriate temperature,and decreased with the increase or decrease of temperature.The LZM activity in 29? group is lower than that in other temperature groups,and the gap getting bigger with time going on.We speculate that high temperature destroys the stability of the hybridization system and damages the normal immune system.3.Influence of gradually temperature change on hsp70 expression of hybrid abaloneThe expression of hsp70 was time-dependent.At the stimulation temperature of 4?,9?,14?,19?,24?,the expression of hsp70 showed a gradual increase in the short time.In 19? group LZM activity reached highest at 12 h,the other temperature group reached its highest at 6 h,then all temperature groups decreased and stabilized.The relative expression of hsp70 in 29? group was slightly decreased from 0 h,then reached the highest at 12 h,and then decreased.We speculated that 29? had a greater stimulus to hybrid abalone,and the up-regulation of hsp70 expression in hybrid abalone was instantaneous.In addition,we found that the relative expression of hsp70 at 48 h was significantly higher than that at 0 h in 4? and 9? group(P<0.05).In 14?,19? and 24? group,no difference of expression of hsp70 was found between 0 h and 48 h(P>0.05).In 29? group,the trend was decreased after 12 h,and significantly lower than that at 0 h(P<0.05).This is related to the suitable growth temperature of hybrid abalone.The hybrid abalone has a good adaptability to the water temperature of 14-24?,and it needs to adapt to the environment through the adaptation mechanism of hsp70 in low temperature environment.And when the long-term high temperature stimulation,the immune mechanism of hybrid abalone was damaged slightly,then hsp70 expression decreased.4.Influence of gradually temperature change on the activities of several immune enzymesSOD:SOD activity in different temperature groups was significantly different at 0 h,and the SOD activity was stable after 2 h expect 4? group,which was probably due to hybrid abalone has adapted to temperature changes.The activity of SOD was kept at a low level at 0 h,2 h and 6 h in the 4? group,and increased after 12 h,reaching the average level.At present,there is nearly no research on the influence of low temperature on the activity of SOD.It was probably because the SOD activity of hybrid abalone was related to its metabolism.The metabolism of abalone was decreased under low temperature environment,which affected the activity of SOD.With the prolongation of time,in low temperature environment,hybrid abalone began to increase the SOD activity to increase immunity.The activity of SOD in 14? group also kept low level and stable,which indicated that 14? was its suitable growth temperature.From 14?,SOD activity decreased when temperatire increased or decreased.But when reaching 29 ? or 4?,SOD activity decreased.We speculated that extreme high temperature or low temperature had a bad influence on the internal environment of hybrid abalone,reducing SOD activity.AKP:In addition to the 4? group,the AKP activity of each temperature group was increased,and then decreased to a low level at 48 h,lower than 0 h,which indicated that hybrid abalone was gradually adapted to the temperature after 48 h.The activity of AKP in 4? group increased continuously,and it was higher than that of other temperature groups at 48 h,with an continuously increasing trend.We speculated that hybrid abalone could enhance the immunity by increasing AKP activity at low temperature.In addition,the activity of AKP in 14? group was slightly fluctuated during the experiment,but it was at low level,which indicated that 14? was suitable for the growth of hybrid abalone.In 29? group,hybrid abalone did not appear obvious difference with other temperature groups.LZM:There no significant difference bettwen 19? and 24? groups(P<0.05).The activity of LZM increased with the temperature increased or decreased,but decreased at 4?,still higher than 19? and 24? group.At 28?,4? and 90?,LZM activity of hybrid abalone remained high level,indicating that hybrid abalone could be well adapted to high temperature or low temperature.The activity of LZM at 19?and 24? was lower than that of other temperature groups,and it was more stable.It indicated that temperature of 19? and 24? made little influence on the LZM activity,being the suitable temperature hybrid abalone. |
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