| The amount of dissolved oxygen in water is one of the important indicators to measure the quality of water,and it is also one of the important factors for water purification.Scylla paramamosain(Scylla paramamosain)is one of the important aquatic products in South China.Affected by various factors such as transportation and breeding density,the oxygen content in the environment of Scylla paramamosain varies greatly,whether it is factoryized Cultivation is still pond culture.The aquaculture water body is affected by various factors such as weather,water flow,temperature and aquaculture density.The dissolved oxygen content will always fluctuate greatly.Hypoxia in the water body occurs from time to time,which will affect the growth and development of cultured organisms.This has greatly hindered and greatly affected the economic income of breeders.Most aquatic animals have a good ability to adapt to the fluctuation of dissolved oxygen in the water body in a short period of time,but if the dissolved oxygen remains at a very low level for a long time,it will cause irreversible damage to their body and even cause death.The main contents of this research are as follows:(1)When organisms are under hypoxic stress,the activity of antioxidant enzymes in the body will change,breaking the original redox balance and causing oxidative stress.The level of SOD in organisms is not stable,and environmental changes will affect the synthesis of SOD.From the experimental results,in the hypoxic stress stage,the SOD activity of the two hypoxic experimental groups was always lower than the SOD activity of the normoxic group,which means that the SOD activity of the hepatopancreas of Scylla sinensis would be inhibited in the hypoxic environment.During the hypoxia stress stage,the MDA content of the hepatopancreas of the scylla crabs in the experimental group was always higher than that of the control group,indicating that the scylla crabs were in a hypoxic environment,which would cause oxidative damage to the cell membrane.Compared with the control group,the ACP and AKP activities of the hypoxia group increased first and then decreased,indicating that hypoxia stress can stimulate the body to produce a non-specific immune response.Hypoxia stress causes the scylla’s body to produce immune stress in a short period of time,which consumes NOS in the body.Under normoxia,after a long period of time in the experiment,the body’s metabolic wastes and the body’s immune regulation mechanism play a role.Effect,a part of NOS is consumed.(2)The full length of Cyclin E gene was cloned.Cyclin E has a total length of 2681 bp,an open reading frame(Open Reading Frame,ORF)length of1008 bp,258 bp 5’non-coding region(5’-UTR)and 1415 bp 3’non-coding region(3’-UTR);ORF encodes a total of 335 amino acids,the theoretical molecular weight of the encoded protein is 220.98 k Da,and the theoretical isoelectric point is 4.65.The results of multiple amino acid comparisons and phylogenetic trees showed that the Cyclin E gene of Scylla sinensis is the closest to Portunus trituberculatus and the roundhead whale in terms of evolutionary relationship.Fluorescence quantitative PCR experiment results show that Cyclin E has the characteristics of extensive expression,and it is expressed in each selected tissue.But the expression in different organizations is different.Cyclin E has the highest expression in the intestine,followed by hepatopancreas and heart,and the least in muscle.The results of fluorescence quantitative PCR showed that the expression level of Cyclin E gene changed the most in the gill tissues of Scylla sinensis after hypoxia stress.After 24 hours of hypoxia stress,the expression level of Cyclin E in the gill tissue of the hypoxia group was significantly reduced,about 1/2 of that of the control group,and the expression level in the hepatopancreas tissue was significantly lower than that in the control group(P<0.01).In muscle tissue,the expression level of Cyclin E in the hypoxia stress group and the control group did not change significantly.(3)The full length of Cyclin G gene was cloned.Cyclin G has a total length of 2277 bp,an open reading frame(ORF)length of 1044 bp,360 bp5′ non-coding region(5′-UTR)and 873 bp 3′ non-coding region(3′-UTR);ORF encodes a total of 347 amino acids,and the encoded protein has a theoretical molecular weight of 190.79 k Da and a theoretical isoelectric point of 4.61.The results of multiple comparisons of amino acids and phylogenetic tree showed that the Cyclin G gene of Scylla sinensis is the most similar in evolutionary relationship with roundhead whale and American crayfish.Fluorescence quantitative PCR experiment results show that Cyclin G is the highest in the intestine,followed by the hepatopancreas,and the least in the stomach.Hypoxia stress has an effect on the expression level of Cyclin G gene.In gill tissues,the expression level of Cyclin G gene was significantly reduced after hypoxia stress(P<0.05),which was about 1/2 of the control group’s expression level;in hepatopancreas tissues,the expression level of Cyclin G gene after hypoxia stress A slight increase.The expression level of Cyclin G gene in muscle tissue did not change significantly compared with the control group. |
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