The Research Of LC₅₀ And Histopathology Of Gill And Hepatopancreas Tissue Of Macrobrachium Nipponense Stressed By Biogenic Amines Owing To Cannibalism During Ecdysis Of Growth

The macrobrachium nipponense,also called freshwater shrimp,is the significant freshwate r breeding species and the exclusive local varieties of freshwater shrimps which cultivated at large-scale in China.It has high economic value and edible value.In resent years,aquaculture environmental conditions,especially residual feeds and decomposed corpse which results from rivalrousness ingestion behavior,cannibalism behavior and holding pelleted feed behavior,ca n influence aquatic environment and intake growing rate,breeding efficiency and survival rate of M.nipponense.Furthermore,it has become one of the most critical negative facts that bring s about lower production,expensive price,notable difference of sizes and undersupplying de mand of market,and also impeded the expansion of market scale of M.nipponense.Biogenic a mines is one of indispensable components of biological active cells,which makes significant d ifference in the aspect of regulating nucleic acid and protein synthesis.However,excessive bio genic amines can produce toxic effects that generated negative or inhibitory effect towards gr owth,development and reproduction of organism.To provide preventive measures for prevention and control of biogenic amines for aquacul ture production and provide theory basis for the period of changing water,the thesis is to study key influence factors of cannibalism behavior,the main type and content change trend of biog enic amines during M.nipponense's ecdysis of growth,and acute toxicity test or sub-acute tox icity test of biogenic amines towards M.nipponense.What's more,its results are also used to p rovide water-quality guideline and target limit of biogenic amines for revision of Water Quali ty Standard for Fisheries?GB 11607-89?and lay a theory foundation for further study of bioge nic amines related resistance genes of M.nipponense.The study has determined that the soluble secretions of baring muscle of M.nipponense became direct factor to induce the same kinds to generate cannibalism behavior during ecdysis of growth;The greater the intensity of the light,the shorter of time,the higher of accuracy,the faster of attack speed,and the higher of lethal attack speed for M.nipponense to find ecdysis individual.M.nipponense can also find the position of the same kinds to generate cannibalism behavior by olfaction without vision.According to the main types and the physical and chemical properties?such as dissolving easily in water,having good stability in the condition of continuous aeration at 25 degrees Celsius?of biogenic amines and the main types existing in aquatic products,the study selected three types of typical biogenic amines included cadaverine,histamines and spermine to tests.We have determined that cadaverine is not only the most abundant type of biogenic amines within 72 hours,but changed most markedly with obvious in decomposed corpse of M.nipponense during ecdysis of growth by the method of HPLC.We have also determined that the medial lethal concentration of 24 hours is 371.733mg/L,and the medial lethal concentration of 48h LC₅₀,72h LC₅₀0 and 96h LC₅₀0 respectively are 218.191mg/L,250.735mg/L and 202.712mg/L under the stress of cadaverine for M.nipponense;According to the formula that MPC is equal to 96hLC₅₀/100 and taking 100 as a protective factor,the study has figured out that the safe concentration of cadaverine for M.nipponense is 2.02712mg/L,it belongs to moderately toxic poisons.Observation showed that M.nipponense has exerts the common behaviors that swimming around in circles,floating head for air,and the individual fightingat the200mg/l,350mg/l,500mg/l stressed levelafter acute poison attack within 2 hours.This phenomenon might be caused by cadaverine stressed,and it can result in difficulty in breathing and contend for the oxygen in water for M.nipponense.After 2 hours,M.Nipponense exerts obvious floating head,wild swimming around the surface of the water and occasional jumping out of the water.Furthermore,its exerts restoring calm,Sinking in the bottom and behaving slowly in the later stages,and several individuals have rolled over but still had vitality.This phenomenon indicated that M.nipponense have been in the verge of death.After15 days,sub-acute toxicity of cadaverine towards M.nipponense can lead to the pathologic changes of the cellular level and the microstructure level in the gill tissue and hepatic tissue under the 5%-20%concentration of 96hLC₅₀.The pancreas tube of hepatic tissue exerts swollen and has severe cavitation.The E-cell which is at the end of pancreas tube reduced gradually,it can hinder the regeneration of hepatopancreas related functional cells;The double biomass membrane of mitochondrion?Mi?has rupture,and the amount of lysosome?Ly?increased significantly.What's more,the rough endoplasmic reticulum?Rer?has swollen,and golgiosome has arranged more loose.These changes can lead to indirect damage of the functional construction of hepatopancreas and influence the biological functions of the organization.The gill membranes has broken,and the structure of chitin layer has also broken.The chrysanthemum structure of gill gland has changed and exerted that enlargement or swollen.The conical nephrocyte has enlarged and lost the original tapered structure;The granulosa cells?GC?of gill filaments and gill axis have also swelled,and the golgi lamella of golgiosome?Go?has occasionally connection fracture.A large number of ribosomes have fallen off rough endoplasmic reticulum?Rer?,and the amount of lysosome?Ly?increased significantly.These changes can inhibit the elimination function of the gill tissue and result in continuous accumulation of cadaverine which existed in the water;Finally,it can induced lesions.According to the conclusion of this study,we gives some suggestions.First of all,we should reduce the illumination effect or produce odor barrier and lower levels of stress to prevent cannibalism behavior effectively during aquaculture period especially ecdysis of growth of M.nipponense.And then we can reduces the amount of death and the water content of biogenic amines.In the second place,we commend that a small exchange water cycle is 3days and the quantity is not less than 1/3,a large exchange water cycle is 15 days to change water comprehensively.Thirdly,we suggest that it should consider putting biogenic amines indicators into Water Quality Standard for Fisheries?GB 11607-89?and set 2.02mg/L as maximum detectable quantity of cadaverine.Finally,we can also consider a more detailed exploration of functional genes that can enhance metabolism and immune at the biogenic amines resistance genes area.