Search

In this study, three genes associated with the metabolism of Pampus argenteus, namely dehydropeptidase (dp), carboxypeptidase A (cpa), and sulfotransferase (sult), were cloned and evaluated using transcriptomics analysis, and their functions in the digestion and absorption of jellyfish were discussed. First, full-length cDNA sequences for dp1, cpa2l, and sult2 were cloned using RACE and confirmed using sequencing. The total length of the dp1 was 2 522 bp, with this transcript including an open reading frame (ORF) of 1 272 bp, a signal peptide composed of 23 amino acids, and an amide hydrolase superfamily domain. The cpa2l transcript was 1 421 bp long and encoded a 1 260 bp ORF. This protein consisted of a signal peptide of 16 amino acids and was characterized by a typical M14 metal carboxypeptidase family domain. sult2 was 1 834 bp in length, producing an ORF of 714 bp, which included a typical sulfatase domain. In addition, homology evaluations of these three P. argenteus genes revealed that they were most similar to the bluefin tuna (Thunnus maccoyii), and phylogenetic tree analysis showed that dp1, cpa2l, and sult2 were all closely related to their corresponding genes from T. maccoyii. RT-qPCR was then used to evaluate the expression levels of these three genes in different tissues and the changes in expression patterns in response to jellyfish ingestion. These experiments revealed that dp1 expression was naturally the highest in the liver (P < 0.05) and significantly increased in the brain, gills (P < 0.01), midgut, and kidney (P < 0.05), but significantly decreased in the muscle (P < 0.05) when compared to that in the non-feeding control. cpa2l expression was highest in the middle intestine in the non-jellyfish feeding group and the kidney in the jellyfish feeding group (P < 0.05) and was shown to be significantly increased in the liver (P < 0.01) but significantly decreased in the midgut and muscle (P < 0.01) when compared to that in the non-feeding group. sult2 expression was highest in the liver (P < 0.05) and significantly increased in the midgut, brain, gill, liver, and kidney in the feeding group compared to that in the non-feeding group (P < 0.05). Taken together, these results suggest that dp1, cpa2l, and sult2 play important roles in nutrient digestion, absorption, and metabolism in P. argenteus, especially in response to jellyfish feeding. In addition, the results of the tissue expression patterns for each of these genes following jellyfish ingestion suggest that dp1 is primarily involved in the regulation of digestion, absorption, and nutrient deposition; cpa2l is involved in the regulation of nutrient metabolism in the liver; and sult2 may play an important role in the overall process of digestion, absorption, and metabolism.

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By decreasing water salinity gradually, the Pampus argenteus juveniles were cultured at water salinity 25, 20, 15 and 10 , for 24 h, 48 h, 96 h and 120 h, respectively, with the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione鄄S-transferase (GST), and glutathione reductase (GR) in liver and the activities of Na+ / K+鄄and Ga2+ / Mg2+鄄ATPase in gill and kidney determined. With the lowering of water salinity and the elongation of treated time, the liver SOD and GST activities had a trend of decreasing after an initial increase (P<0郾05), while the CAT activity was lower than the control except that it had a slight increase at salinity 20 cultured for 24 h and at salinity 15 cultured for 48 h (P<0郾05). The liver GPX activity had an increasing trend (P<0郾05), while the GR activity at salinity 15 cultured for 24 h increased first and then fell down to a relatively low level (P<0郾05). The Na+ / K+鄄and Ga2+ / Mg2+鄄ATPase activities in the gill and kidney also decreased after an initial increase (P<0郾05), only the increase of ATPase activity at the thresholds of water salinity and treated time differed between the two organs. The results indicated that the decrease of water salinity could effectively stimulate and enhance the antioxidant enzyme activities in juvenile P. argenteus liver and the ATPase activities in its gill and kidney, and thereby, could effectively eliminate the excessive reactive oxygen species (ROS), sustain the intracellular homeostasis, and minimize the body damage. However, characterized by certain specificity and time sequentiality, the activation of test enzymes could also be inhibited when the salinity varied beyond the tolerance range of the body. [ABSTRACT FROM AUTHOR]