Polka dot grouper Cromileptes altivelis fingerlings require high protein and moderate lipid diets for optimal growth and nutrient retention

An 8‐week comparative slaughter experiment was carried out to determine the effect of dietary protein and lipid on growth, apparent digestibility (AD) and nutrient retention of polka dot grouper Cromileptes altivelis. Fingerlings were fed diets that varied in crude protein (CP) at 55 g kg^?1 increments between 410 and 630 g kg^?1 dry matter (DM) and at either a moderate (150 g kg^?1 DM) or high (240 g kg^?1DM) lipid concentration. Each diet was fed to satiety twice daily to four replicate tanks (110 L) of fish. One replicate block of tanks comprised 150 fish of mean (±SD) initial weight of 9.6 ± 0.29 g, which were distributed equally to 10 tanks. The other three replicate blocks of tanks comprised 300 fish of 12.6 ± 0.45 g, which were distributed equally to 30 tanks. Tanks were provided with filtered and heated (29 ± 0.5 °C) seawater in a flow‐through system within a laboratory where photoperiod was maintained at 12 : 12 h light–dark cycle. Voluntary food intake was not significantly affected by either the CP or lipid concentration of the diet (mean ± SD of 1.93 ± 0.146 g week^?1) but there was a trend for intake to be higher on the moderate compared with the high lipid diets (mean ± SEM of 1.97 versus 1.89 ± 0.033 gweek^?1, respectively). Daily growth coefficient (DGC) and food conversion ratio (FCR) improved linearly (P < 0.01) with increasing dietary CP (from 0.94 to 1.35% day^?1 for DGC and 1.58 to 1.00 g DM g^?1 wet gain for FCR) and these responses were almost coincident for each of the lipid series. The AD of CP increased linearly with increasing dietary CP (from 46.8 to 74.1%) and was independent of dietary lipid. Apparent digestibility of energy increased curvilinearly with increasing dietary CP, with the quadratic component being more prominent for the high‐lipid series. Increasing the amount of lipid in the diet markedly increased the lipid content of the fish from an initial composition (mean ± SD) of 173 ± 7.3 g kg^?1 to a final composition (mean ± SEM) of either 217 or 250 ± 5.9 g kg^?1 for moderate and high‐lipid series, respectively. Total body lipid content tended to increase linearly with increasing dietary CP for the high‐lipid series but with an opposite effect for the moderate‐lipid series. The retention of digestible nitrogen decreased linearly with increasing dietary CP but at a steeper rate for the moderate, compared with the high, lipid series (from 62.7 to 35.7%, slope ?0.115 for moderate‐lipid and 54.6 to 41.9%, slope ?0.050 for high‐lipid). A quadratic function of dietary CP concentration best explained the retention of digestible energy with the curvilinearity being more marked for the high, compared with the moderate, lipid diet series. While there was some indication that ingested lipid spared dietary protein, the results showed a far greater propensity of polka dot grouper fingerlings to use protein as the prime dietary energy source. Diets for juvenile polka dot grouper should contain not less than 440 g digestible protein kg^?1 DM and at least 150 g lipid kg^?1 DM.     

Minimising aerobic respiratory demands could form the basis to sub-lethal copper tolerance by rainbow trout gill epithelial cells in vitro

Mechanisms of Cu tolerance were investigated in respiratory epithelial cell cultures, from rainbow trout gills, by studying O₂ consumption and protein synthesis rates, intracellular Na concentration and TER. The lowest concentration found to reduce O₂ consumption was 25 M Cu. This did not affect either protein synthesis rate or intracellular Na concentration and was interpreted in terms of copper tolerance; i.e., how these two energetically demanding processes are maintained despite a reduction in aerobic ATP supply. The relationship between protein synthesis rate and synthesis cost is exponential and the cost of protein synthesis in gill cells was found to be minimal (i.e., this cell occupies a position on the asymptotic section of the protein synthesis rate/synthesis cost model) and unaffected by 25 M Cu. Thus protein synthesis rates could be maintained since any reduction would represent an insignificant energy saving. Intracellular Na concentrations and O₂ consumption rates were linearly correlated suggesting reducing intracellular maintenance costs would have a greater significance in terms of overall energetic conservation. Intracellular Na maintenance costs, calculated from O₂ consumption rates and intracellular Na concentrations, were found to decline after exposure to 25 M Cu. Since TER was unaffected this implied the reduced costs arose from membrane `channel arrest'. Thus the Na/K ATPase energy demands, associated with maintaining intracellular Na concentration, could be reduced by decoupling metabolic demand and membrane function. Therefore this study may demonstrate how the flexibility of cellular energetics enables gill epithelial cells to tolerate sub-lethal Cu.     

Characterization of a cDNA encoding a homolog of actin-related protein 4 from a marine red alga Porphyra yezoensis

ABSTRACT:   A cDNA ( PyARP4 ) containing an open reading frame for a protein of 573 amino acids was identified in the marine red alga Porphyra yezoensis . The conceptual PyARP4 protein exhibits significant similarity to actin-related protein (ARP) 4 in the terrestrial plant Arabidopsis . Comparison of the deduced amino acid sequence showed moderate sequence identity (30%) to a conventional actin in P. yezoensis , as seen in comparisons between ARP and conventional actins of other organisms. A putative bipartite nuclear localization signal and an actin motif were found within the PyARP4 amino acid sequence. In a phylogenetic analysis, the PyARP4 was found to cluster with the ARP4 of other organisms. The expression level of PyARP4 did not change significantly among four developmental stages of life cycle and was lower than that of a conventional actin. This cDNA therefore may serve as a useful internal standard in gene expression analyses of differentially expressed genes in P. yezoensis .     

Sunflower seed meal as a protein source in diets for Tilapia rendalli (Boulanger, 1896) fingerlings

This study tested the use of sunflower seed meal as a dietary protein replacement for fishmeal in practical diets for tilapia fingerlings. In order to determine the optimum substitution level for this species, sunflower seed meal was used to replace 10%, 20%, 30%, 40% and 50% of the fishmeal protein in diets containing 40% protein overall. During a 70‐day feeding period, diets containing 10% and 20% plant protein provided the best growth and feeding efficiency results, with values statistically similar to those of the control diet based on fishmeal as the sole protein. The unitary feeding cost index showed the highest profit with diets containing 20% sunflower seed meal. Growth depletion observed with diets containing higher sunflower seed meal percentages is explained by increasing Phe and Met deficiencies, and high non‐digestible fibre content. It was concluded that sunflower seed meal is a suitable feed ingredient for tilapia complete diets when it constitutes up to 20% of the dietary protein.     

Dynamics of plasma free amino acids in rainbow trout (Oncorhynchus mykiss under variety of dietary conditions

Plasma amino acid profiles in the systemic circulation of rainbow trout acclimated to diets containing different protein sources, with and without supplementation with free amino acids, were monitored for up to 120 hours after consumption of the diets. Plasma concentrations of lysine, methionine, and isoleucine increased more rapidly after feeding a diet supplemented with these amino acids in free form and, depending upon the increase in plasma concentration, remained at concentrations above those in fish fed the basal diet for at least 24h after feeding. Dietary supplementation with isoleucine increased plasma concentrations of leucine and valine as well as of isoleucine. Maximum plasma concentrations for most amino acids were attained between 12 and 24h postprandial. Dietary inclusion of gelatin caused more rapid elevations in plasma glycine and serine than did free glycine. Feeding at three hour intervals resulted in stable plasma concentrations of individual amino acids in contrast to the fluctuations occurring when fish were fed once daily. Frequent feeding favoured a higher proportion of protein to lipid in body composition.     

Effect of shrimp head protein hydrolysates on the state of water and denaturation of fish myofibrils during dehydration

ABSTRACT:   To utilize fisheries waste products as food materials with functional properties, shrimp head protein hydrolysates (SHPH) from three species of shrimp, that is, Northern pink shrimp ( Pandalus eous ), Endeavour shrimp ( Metapenaeus endeavouri ) and Black tiger shrimp ( Penaeus monodon ), were produced by enzymatic hydrolysis using endopeptidase derived from Bacillus subtilis and exopeptidase derived from Aspergillus oryzae at a level of 0.1% (w/w). SHPH were rich in protein (90–91%) and amino acids (71–84%) but little fat (0.01–0.02%). The average molecular weight of SHPH was 300–1400. The effect of 5% SHPH (dry basis) addition on the state of water and denaturation of lizard fish myofibrils (Mf) during the dehydration process was evaluated by the desorption isotherm and the Ca-ATPase activity, and compared with the effect of sodium glutamate (Na-Glu). SHPH decreased the water activity and the Ca-ATPase inactivation, and increased monolayer sorbed water and multilayer sorbed water of Mf, although these effects of SHPH were smaller than those of Na-Glu. These findings suggest that the SHPH suppressed dehydration-induced denaturation of myofibrillar protein by stabilizing the hydrated water surrounding myofibrils.     

中华绒螯蟹血淋巴和肝胰腺的总蛋白含量与性早熟的关系

中华绒螯蟹扣蟹性腺发育与肝胰腺和血淋巴的蛋白质浓度相关.性早熟前后,雌雄扣蟹肝胰腺总蛋白浓度分别由(121.17±44.50)mg@g-1和(89.43±21.86)mg@g-1下降至(81.08±5.84)mg@g-1和(70.58±9.90)mg@g-1,雌性扣蟹的肝胰腺占体重的比值也由8.18%降至3.90%.血淋巴总蛋白浓度正常发育的雌性扣蟹为(99.55±12.06)mg@mL-1,明显高于性早熟雌性扣蟹的(72.26±17.87)mg@mL-1;而雄性扣蟹性早熟前后的血淋巴总蛋白浓度无显著差异.肝胰腺总蛋白浓度二秋龄雌蟹高于性早熟雌性扣蟹,但它们之间的血淋巴总蛋白浓度没有显著差异.二秋龄雄蟹的血淋巴和肝胰腺总蛋白浓度与性早熟雄性扣蟹相当,差异不显著.     

甘露青鱼肌肉营养分析和评价

取材太湖流域无锡甘露水产公司养殖的大青鱼,采用化学及仪器分析手段,对青鱼含肉率及肌肉营养成分进行了分析测定,含肉率为71 08%,肌肉中蛋白质含量为16 56%,脂肪含量为14 08%,其中70 73%为不饱和脂肪酸,18种氨基酸总量为14 91%,8种人体必需氨基酸的含量为6 07%,4种鲜味氨基酸的含量为5 62%,还含有多种微量元素,通过大量基础数据综合评价甘露青鱼的营养价值。     

巴西橡胶树橡胶粒子中2个含RicinB_Lectin_2结构域蛋白质研究初报

采用不同提取液,从洗涤过的巴西橡胶树橡胶粒子中提取蛋白质,并对其进行电泳分离与质谱鉴定。分离鉴定了2个含RicinB_Lectin_2结构域的糖基识别蛋白质,分别命名为HbRBLLP-1和HbRBLLP-2。这2个蛋白质可能是橡胶粒子膜蛋白质或是与橡胶粒子有较强的相互作用的蛋白质。对HbRBLLP-1及HbRBLLP-2进行生物信息学分析,结果表明它们的RicinB_Lectin_2结构域均仅有1个Q-x-W模体,而非蓖麻毒素B链所具有的(Q-x-W)3模体。