| In this research,Lota lota with high value and broad development prospect was studied.Firstly,the flesh content of Lota lota and the nutrients in their muscles were determined,and its digestive system was studied with anatomical and histological methods.Then,the activity of digestive enzymes in the tissues and organs of Lota lota was studied.The study provides the theoretical basis for artificial breeding of Lota lota,enriches the basic digestive and physiological knowledge,and offers the theoretical reference for the further development and utilization of the superior species resources.The results are as follows:1.The flesh content of Lota lota was 74.26%,the moisture content 80.11%,the crude protein content 17.24%,crude fat content 0.58%,and ash content 1.09%.Altogether 17 amino acids were detected in the muscle,of which the total content of 7 essential amino acids was32.95%(dry sample),accounting for 40.74% of the total amino acids.The content of 4 delicious amino acids(DAA)was 29.63%(dry weight),accounting for 36.64% of the total amount of amino acids.The essential amino acids index(EAAI)was 73.01.The EPA content of the total fatty acids was 4.32% and the DHA content was 10.69%(dry weight),higher than a variety of economic fish.The ratios of n-6/n-3 and PUFA/SFA in muscle indicated that its food safety meets the requirements recommended by the UK Department of Health.The muscle of Lota lota was rich in K,Mg,Zn and other mineral elements,which indicates that Lota lota is a kind of fish with high nutritional value.2.The methods of histology and anatomy were utilized to study the digestive tract of Lota lota.The ratio of Lota lota to the intestine length was 0.82±0.13.The stomach of Lota lota has a strong elasticity,and when expanded,it shows a "U" shape.The gastric mucosa epithelium is a simple columnar cell,and a large number of gastric glands are distributed in the lamina propria between the mucosa epithelium.Intestinal mucosa epithelium is mainly made up of simple columnar cells and goblet cells.Intestinal mucosal fold number,height and width on the pipe wall,mucous membrane layer thickness reduce from the former to the latter,the number of goblet cells increases from the front to back in turn,the thickness of muscular and serosa layer shows a trend of the change of the high-low-high.The histology and morphology of the digestive system of Lota lota matched its feeding habits.3.The distribution order of protease activity in different organs and tissues of Lota lota was gastric,pylorus,anterior intestine,middle intestine,posterior intestine and liver in terms ofquantity from large to small,the activity of pepsin was significantly higher than that of other tissues(P< 0.05).The amylase activity in different organ tissues of Lota lota was highest in liver,followed by anterior intestine,pylorus,middle intestine,posterior intestine,and the lowest in stomach.The sequence of lipase activity in Lota lota was as follows: anterior intestine,middle intestine,posterior intestine,the pylorus liver and stomach,indicating that the digestion and absorption of proteins are mainly in the stomach,followed by the pylorus and the intestine.Liver,pylorus and intestine are the main organs of amylase production.The digestion and absorption of fat mainly concentrated in the intestine.Pepsin has the highest activity in strongly acidic condisions,gastric amylase has the highest activity when it is slightly acidic,and the optimal p H values of protease,amylase and lipase in other parts of the digestive tract are in the neutral or alkaline range. |
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