Abstract
Temperature is a significant environmental factor in aquaculture. To investigate the physiological responses during temperature fluctuation (28~13°C), experimental shrimps (Litopenaeus vannamei) were treated with gradual cooling from acclimation temperature (AT, 28°C) to 13°C with a cooling rate of 7.5°C/day and rose back to 28°C at the same rate after 13°C for 24 h. Hepatopancreas histological changes, plasma metabolites concentrations, relative mRNA expression of unfolded protein response (UPR) pathway and apoptosis in hepatopancreas and hemocyte were investigated. The results showed that with the decline of temperature, the number and volume of the secretory cells in hepatopancreas increased significantly, the tubule lumen appeared dilatated, and the epithelial cell layer became thinner. The contents of glucose (Glu) significantly decreased to the minimum value of 13°C for 24 h. The contents of triglyceride (TG), total cholesterol (TC), and total protein (TP) increased and reached the peak of 13°C for 24 h. Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities in plasma reached the lowest and highest value in 13°C, respectively. The expressions of all genes related to UPR and apoptosis in the hepatopancreas and hemocytes were significantly changed during the cooling process and reached the highest level of 13 and 13°C for 24 h, respectively. During re-warming stage, the histopathological symptoms got remission and each of the plasma metabolite concentrations and gene expressions returned to AT levels. These results revealed that pacific white shrimp can adapt to a certain level of temperature fluctuation by self-regulation.
Highlights
The pacific white shrimp Litopenaeus vannamei, with a wide range of salt-tolerance, rapid growth, and other characteristics suitable for intensive aquaculture, has become one of the most important aquaculture shrimps in the world
Previous studies have indicated that many extreme weather events which were associated with drastic temperature fluctuation can directly affect the growth, physiological performance, and survival of animals (He et al, 2018; Zhang et al, 2019)
The results showed that lipids (TC, the major components of lipids, supply and store energy) and protein (TP provides energy and transports various metabolites) in plasma responded more rapidly to temperature fluctuation, while Glu remained stable before 13°C and recovered to AT levels after temperature rose back to 28°C
Summary
The pacific white shrimp Litopenaeus vannamei, with a wide range of salt-tolerance, rapid growth, and other characteristics suitable for intensive aquaculture, has become one of the most important aquaculture shrimps in the world. A variety of environmental stimuli affect the growth of shrimp, such as changes in pH (Han et al, 2018a), salinity Previous studies have indicated that many extreme weather events which were associated with drastic temperature fluctuation can directly affect the growth, physiological performance, and survival of animals (He et al, 2018; Zhang et al, 2019). Our previous study has indicated that glucose-regulated protein 78 kDa (GRP78) was significantly up-regulated in the hepatopancreas of L. vannamei under 13°C for 24 h cold-stress (Fan et al, 2016). GRP78, known as immunoglobulin-binding protein (BIP), is a central regulator of endoplasmic reticulum stress (ERS) and regulated the process of unfolded protein response (UPR) and apoptosis (Dejean et al, 2006; Nakka et al, 2010). Studies on ERS are mainly focused on mammals and the UPR pathway (Cao and Kaufman, 2012)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call