Effects Of Light On Physiological Process In Plasma Of Crassostrea Gigas

For marine organisms,especially those living in mudflats and intertidal areas,they are likely to be affected by light radiation.Sunlight mainly includes photosynthetically active radiation(PAR),UVA and UVB wavelengths.Compared with PAR and UVA,UVB radiation(280-320 nm)has higher intensity and stronger penetrating power,and the increasing UVB radiation in the earth’s environment will cause long-lasting potential disturbance to organisms.Crassostrea gigas is an important cultured shellfish in China,and its whole life history,whether wild or cultured,is likely to be influenced by solar light,especially UVB radiation.In this study,we used the value behavioral tests and combined multi-omics analysis techniques to deeply explore the effects of different simulated light conditions on the substances in the plasma of C.gigas.The specific results are as follows:1.In this study,a bivalve shell valve detection system was established based on the Hall effect,and the behavioral characteristics of C.gigas.under different light conditions were analyzed by comparing the induced voltage,calculating the curve fitting equation,and recording the valve opening amplitude(VOA)and the valve opening duration(VOD).The results showed that the behavioral changes of C.gigas.were divided by 10 days,and the VOA showed an overall trend from smooth to drastic,while the trend of VOD was the opposite of VOA,indicating that the overall adaptation trend of C.gigas to different light conditions was adjusted.Compared with PAR and the dark control group(Dark),the light radiation group with compound UVB(PAR+UVB)had more serious effects on the behavior of C.gigas.Therefore,simulated light conditions containing UVB were selected as the treatment conditions for subsequent histological analysis of the effects of light on physiological processes in the plasma of C.gigas.2.The complex composition of plasma substances in the open-tubular hemolymph of shellfish can be an important object of study to show the extent of disturbance of their homeostasis by external environment.In this study,we analyzed the effects of UVB-containing simulated light exposure on plasma substances in C.gigas by multi-omics integration of transcriptome,proteome and metabolome.The results showed that,firstly,plasma phospholipase class activity and PE/LPE content were significantly up-regulated and PC/LPC content showed significant down-regulation after exposure,indicating that dynamic regulation of membrane lipid composition occurred in C.gigas.Secondly,C.gigas may activate the synthesis of dTMP,dATP and dGTP by upregulating NDPK as the core nucleotide metabolism-related enzymes to compensate for the impaired nucleotide metabolism throughout the body.Finally,C.gigas increased lipid catabolism while reducing sugar hydrolysis to meet normal energy supply.In conclusion,UVB-simulated light disrupts cell membranes,promotes nucleotide metabolism,and inhibits energy metabolism.In addition,DEPs and DEGs in plasma(Nucleoside diphosphate kinase,Malate dehydrogenase,Hydroxyacyl-coenzyme A dehydrogenase)and metabolites(Uridine,Adenine,Deoxyguanosine,Guanosine,Xylitol)can be used as biomarkers of changes in shellfish response to UVB radiation to assess the effects of environmental UVB on shellfish.In summary,the results of this study enrich the evaluation of the effects of light on shellfish.Using the valve behavior test system and plasma light response markers established in this study,we can conduct light response "physical examination" of the ecosystem and shellfish in the farm,analyze the impact of the culture environment on them,and further optimize the culture management to help upgrade and improve the quality of shellfish culture technology.