Influence of dietary zinc on growth, zinc bioaccumulation and expression of genes involved in antioxidant and innate immune in juvenile mud crabs (Scylla paramamosain)

Abstract

The aim of the present study was to investigate the effects of dietary Zn level on growth performance, Zn bioaccumulation, antioxidant capacity and innate immunity in juvenile mud crabs (Scylla paramamosain). Six semi-purified diets were formulated to contain dietary Zn levels of 44·5, 56·9, 68·5, 97·3, 155·6 or 254·7 mg/kg. Dietary Zn level significantly influenced percentage weight gain (PWG), with the highest observed in crabs fed the diet containing 97·3 mg/kg Zn. Tissue Zn concentrations significantly increased as dietary Zn levels increased from 44·5 to 254·7 mg/kg. Retention of Zn in hepatopancreas increased with dietary Zn levels up to 68·5 mg/kg and then significantly decreased. Moreover, inadequate dietary Zn (44·5 and 56·9 mg/kg) reduced antioxidation markers including total superoxide dismutase (SOD) and Cu/Zn SOD activities and total antioxidant level. Crabs fed the diet with 44·5 mg/kg Zn also showed significantly lower expression of genes involved in antioxidant status, such as Cu/Zn SOD, glutathione peroxidase, catalase and thioredoxin than those fed diets containing 68·5 and 97·3 mg/kg Zn. The highest activities of phenoloxidase and alkaline phosphatase were recorded in crabs fed the diets containing 68·5 and 97·3 mg/kg Zn. Expression levels of prophenoloxidase and toll-like receptor 2 were higher in crabs fed the 97·3 mg/kg Zn diet compared with crabs fed the other diets. Based on PWG alone, the optimal dietary Zn level was estimated to be 82·9 mg/kg, with 68·5 to 97·3 mg/kg recommended for maintaining optimal Zn bioaccumulation, oxidation resistance and innate immune response of juvenile mud crabs.

Environmental salinity and dietary lipid nutrition strategy: Effects on flesh quality of the marine euryhaline crab Scylla paramamosain

“…The formulations and proximate compositions of the experimental diets are shown in Table S1, and the fatty acid compositions of lipid sources and diets are presented in Tables S2 and S3, respectively. The diets, formulated to satisfy the nutrient requirements of mud crab (NRC, 2011), were prepared following the protocol described in detail previously (Luo et al, 2020). Briefly, all dry ingredients were ground into fine powder with particle size < 177 μm, and micronutrients including minerals and vitamin premixes were added by the progressive enlargement method.…”

“…RNA extraction, reverse transcription and quantitative real-time PCR were conducted according to methods described in detail by Luo et al (2020). Briefly, total RNA was extracted from hepatopancreas and muscle samples using Trizol reagent (Vazyme, China), with quality and concentration confirmed by agarose gel electrophoresis and ultra-micro spectrophotometer (Nanodrop 2000, Thermo Fisher Scientific), respectively.…”

Dietary manganese levels influence growth, manganese bioaccumulation and expression of genes involved in antioxidant response of swimming crab ( Portunus trituberculatus )

“…Six isonitrogenous (~450.0 g/kg crude protein) and isolipidic (~100.0 g/kg crude lipid) experimental diets were formulated to contain different Mn levels (MnSO 4 •H 2 O as Mn source, Sinopharm Chemical Reagent Co., Ltd, Shanghai, China); the dietary Mn concentrations were analysed to be 9.8 (basal diet), 20.2, 29.7, 38.2, 65.6 and 123.6 mg/ kg (Table 1). The experimental diets were produced according to the method described in detail previously (Luo et al, 2020). Briefly, the ground ingredients were blended in a Hobart-type mixer and cold-extruded pellets produced (F-26, Machine factory of South China University of Technology) with pellet strands cut into two uniform sizes (3-and 5-mm diameter pellets) (G-250, Machine factory of South China University of Technology).…”

“…Gene expression was determined by reverse-transcriptase quantitative polymerase chain reaction (qPCR). RNA extraction, reverse transcription and real-time qPCR were carried according to methods described in detail previously (Luo et al, 2020). Briefly, total RNA of hepatopancreas were extracted by using TRIzol Reagent (Vazyme, China) according to manufacturer's instructions.…”

“…As a commercially typical marine crab species, swimming crab is widely distributed in the Pacific and Indian oceans (Hamasaki et al, 2011). Due to the success of artificial propagation, intensive artificial aquaculture has become the main mode of culture in swimming crab (Jin et al, 2013;Luo et al, 2020). However, feeding with trash fish or shellfish for swimming crabs may result in environmental damage and spread of infectious diseases (Jin et al, 2013).…”