Alkaline phosphatase in shrimp Artemesia Longinaris: Response to feed

Abstract

Abstract: The purpose of this study was to evaluate the alkaline phosphatase activity in haemocytes and midgut gland of the argentine shrimp Artemesia longinaris in relationship with different doses of vitamin D3 in feed and to estimate its potential use as biomarker for nutritional stress. A nine-week trial was carried out with juvenile shrimps in aquaria. Animals were fed on semipurified feeds with different levels of vitamin D3 (0; 0.2; 0.375; 0.75 and 1 mg vitamin D3 kg-1 feed). Treatments without vitamin D in haemocytes revealed the significantly highest protein content (P<0.05), as the lowest values were recorded on 0.2 and 1 mg vitamin D kg-1 treatments. The analysis of protein content of midgut glands revealed a maximum content for diets containing 0.2 and 0.75 mg Vitamin D kg-1. The optimum pH value for alkaline phosphatase in midgut gland of A. longinaris was 9.5. The results show the occurrence of alkaline phosphatase activity in the tissues of shrimp A. longinaris being studied, describing higher enzymatic activity values in haemocytes than midgut gland. The highest enzyme activity in haemocytes was observed on shrimps fed without vitamin D (1.235 abs min-1 mg protein-1), however, in midgut gland, the activity varied from 0.141 to 0.297 abs min-1 mg protein-1, with the highest values on 0 and 1 mg vitamin D kg-1. On the other hand, histological analysis of the midgut gland confirmed a good health of the shrimp fed 0.375 and 0.750 mg vitamin D kg-1 that is why they were used as optimal values for determining enzymatic activity, shrimp fed diets without vitamin D or 1 mg kg-1 showed signs of malnourishment. The results indicate that alkaline phosphatase activity in A. longinaris was influenced by vitamin D in feed and may be used as a biomonitor of nutritional stress.