Effects of dietary starch levels on the growth,plasma metabolites and expression of genes involved in glucose transport and metabolism in Pelodiscus sinensis juveniles

A 10‐week feeding trial was conducted to evaluate the growth performance, glucose transport and metabolism of Chinese soft‐shelled turtles (Pelodiscus sinensis) exposure to graded levels of dietary starch (0.52%, 7.43%, 14.74%, 22.99% and 31.38%). The 360 turtles (initial body weight, 12.94 ± 0.50 g) with 12 replicates were randomly assigned to five experimental diets. The highest weight gain and specific growth rate (SGR) were observed in 7.43% group and the lowest in 31.38% group. The protein efficiency ratio, whole‐body lipid contents, hepatic glycogen contents and the 4‐hr postprandial plasma glucose levels were significantly increased with the increment of starch levels (p < .05). In contrast, the daily feed intake and feed conversion ration were significantly declined (p < .05). The mRNA levels of glucose transporter 2, glucokinase, pyruvate kinase, malic enzyme and acetyl‐CoA carboxylase alpha genes in the liver significantly increased as the increase in starch levels at 4‐hr and 24‐hr post feeding (p < .05). No significant differences were observed in the expression of gluconeogenesis genes at each time point (p > .05). These results suggested that dietary addition of starch up‐regulated hepatic glycolysis, glycogenesis and lipogenesis genes expression, but the deficient response of gluconeogenesis to dietary starch might be part of the causes limited the starch utilization. Based on the secondary polynomial regression of SGR, y = ?0.0011x² + 0.028x + 1.63 (R² = 0.9292), the 12.73% inclusion level of dietary starch was recommended in juvenile turtles.     

不同雌雄配比对中华鳖人工繁殖受精率的影响

研究了中华鳖(Pelodiscus sinensis)人工繁殖不同雌雄配比的受精率差异,结果显示:在放养密度3750~4500 kg/hm2,亲鳖规格♀1.5 kg/只、♂2.0 kg/只条件下,雌雄配比可达8∶1。在不增加水体面积和投资情况下,雌雄比8∶1与5∶1相比多产受精卵13500~18000枚/hm2,可增加纯利润27000~30000元/hm2。     

复方中草药对中华鳖营养免疫及抗氧化功能的影响

为研究复方中草药对中华鳖营养免疫及抗氧化功能的影响,试验在水温27~29℃时,将体质量25~35g的中华鳖(Pelodiscus sinensis)幼鳖饲养在池底铺10cm细沙的1.0m×0.8m×0.8m水泥池中,分别投喂添加0%(对照组)、1%、3%和5%复方中草药(芹菜籽粉∶葡萄籽粉∶薏仁粉=1:1:1)的饲料。养殖60d后主要测定幼鳖血液中的抗氧化指标。结果表明:1%、3%、5%中草药组血清谷胱甘肽活性(GSH-Px)均显著高于对照组,剂量效应规律较为明显。5%中草药组血清总抗氧化能力(T-AOC)显著高于对照组。1%中草药组血清过氧化氢酶(CAT)活性显著高于对照组,剂量效应规律不明显。1%、3%和5%中草药组血清丙二醛(MDA)含量均显著低于对照组。3%和5%中草药组幼鳖血清尿素氮(BUN)水平显著低于对照组,表明中草药可提高中华鳖幼鳖蛋白质利用效率。综上所述,从中华鳖幼鳖血清T-AOC活性、MDA含量以及BUN水平等指标来看,结合经济性原则,该复方中草药添加量以3%较为适宜。另外,该复方中草药对于中华鳖幼鳖整个机体的免疫状态的影响规律不明显,其改善中华鳖抵抗力的内在机制还有待深入研究。     

中华鳖对嗜水气单胞菌粗脂多糖(LPS)的免疫应答

将采用温酚法从嗜水气单胞菌(Aeromonas hydrophila)、柱状嗜纤维菌(Cytophaga columnaris)和叉尾鮰爱德华菌(Edwardsiella ictaluri)中提取的粗脂多糖(crude lipopolysaccharide,LPS)作为免疫原,注射接种中华鳖(Pelodiscus sinensis)后,通过测定受免鳖的交叉凝集抗体效价、肾脏和血液中吞噬细胞的吞噬活性和对A.hydrophila活菌细胞内杀菌活性,比较了3种致病菌的粗LPS对中华鳖的免疫原性。试验结果表明,从3种致病菌中提取的粗LPS对中华鳖均具有较强的免疫原性,受免鳖的血清中存在对3种致病菌的交叉凝集抗体,与对照鳖相比,肾脏和血液中吞噬细胞对吞噬原的吞噬活性和对A.hydrophila活菌杀菌活性明显上升。说明在3种供试菌的粗LPS上不同程度地存在3种致病菌的共同保护性抗原。     

Effects of dietary vitamin E level on growth and tissue lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis (Wiegmann)

A feeding trial was conducted to determine the effect of dietary vitamin E supplementation on growth, liver lipid peroxidation and liver and muscle vitamin E level of soft‐shelled turtle, Pelodiscus sinensis. Eight experimental diets analysed to contain 0–457 IU vitamin E kg^?1 were fed to juvenile soft‐shelled turtle of 4.8 g initial body weight for 12 weeks. Weight gain (WG) of the turtles fed the diet containing no vitamin E was significantly lower than those fed diets containing 83–457 IU vitamin E kg^?1 (P<0.05). Feed conversion ratio and protein efficiency ratio showed similar trends to that of WG. No significant difference (P>0.05) was found in whole‐body composition among turtles fed the different diets. Dietary vitamin E requirement using WG as the response and estimated using the broken‐line regression model is approximately 88 IU kg^?1. Liver and muscle vitamin E content increased when dietary vitamin E level increased. Ascorbate‐induced lipid peroxidation in liver tissue of turtles fed diets containing 0 and 17 IU vitamin E kg^?1 was significantly (P<0.05) greater than those fed diets containing high vitamin E (≥35 IU kg^?1).     

The effects of vitamin E on non-specific immune response of the juvenile soft-shelled turtle <Emphasis Type="Italic">Pelodiscus sinensis</Emphasis>

ABSTRACT:   This study was conducted to determine the effect of dietary vitamin E supplements on non-specific immune responses in juvenile soft-shelled turtles. Turtles were fed diets supplemented with vitamin E at 0 (control), 50, 250, 500, 1000 and 5000 mg/kg, respectively, for 4 weeks. Results showed that blood cell phagocytosis and serum bactericidal activity were significantly improved in turtles from two diets (250 and 500 mg/kg vitamin E supplementation), while had no significant improvement in turtles from the three remaining diets (50, 1000 and 5000 mg/kg vitamin E supplementation) when compared to turtles from the control group. Serum bacteriolytic activity in turtles from diets with 50, 250, 500 and 1000 mg/kg vitamin E supplementation were higher than activity levels quantified for the control group, but no significant difference was observed between the 5000 mg/kg vitamin E supplementation diet and the control diet. The results suggest that vitamin E has an upper and lower threshold for improving non-specific immune function in soft-shelled turtles, and the optimal supplementation may be between 250 and 500 mg/kg.     

中华鳖胚胎发育与胚胎分期

孵化第1天开始进行拍照记录,从第7天开始连续解剖研究中华鳖胚胎发育的整个过程,分析孵化过程中胚胎的器官变化。结果表明：中华鳖孵化周期平均为46天,以胚胎的日龄、形态特征和内部结构的变化为主要依据,从中华鳖卵产出到稚鳖的孵出,将整个胚胎的发育过程分为26期,第2~13期依据卵黄囊血管区、眼睛、心脏等形态变化进行分期,14~26期是以四肢、背甲及腹甲的变化特征为主要分期依据,详细描述了每一期的形态特征,并对具有典型特征的各期配以周详的图片进行比较。描述中华鳖胚胎发育不同时期的关键表型特征,有利于对中华鳖的整个孵化过程有更加全面的认识。     

Newly identified C‐type lysozyme in Chinese soft‐shelled turtle (Pelodiscus sinensis) exhibits potent antimicrobial activity

Lysozymes play vital roles in humoural immune response against bacterial invasion by its lytic activity. In the present study, a new C‐type lysozyme was identified and characterized from Chinese soft‐shelled turtle Pelodiscus sinensis. The full‐length cDNA of PslysC was of 923 bp, encoding a polypeptide of 148 amino acid residues. The multiple alignments and phylogenetic relationship analysis revealed the highly enzyme‐related conserved residues. The real‐time PCR analysis suggested that PslysC was constitutively expressed in a wide range of tissues with highest level in blood cells and liver. The expression of PslysC could be significantly up‐regulated under Aeromonas jandaei infection and ammonia exposure, while no significant changes were found under Poly I:C infection. The rPslysC protein was expressed in E. coli and purified by Ni‐NTA. The optimal pH and temperature for rPslysC protein lytic activities were determined at pH 7 and 30℃. rPslysC can inhibit the growth of eight kinds of Gram‐negative bacteria, and three kinds of Gram‐positive bacteria. The binding activity of rPslysC to different microbial polysaccharides and microorganism was analysed. The results showed that rPslysC could bind to selected bacteria, and exhibit a strong binding activity to lipopolysaccharide and peptidoglycan, but a weak binding activity to β‐glucan. This suggests that the binding activity might be the major mechanism of action to realize the antibacterial activity. The present study will provide helpful evidence to further understand the innate immunity of P. sinensis, and the interaction mechanisms of C‐type lysozymes with bacterial membranes.     

中华鳖弗氏柠檬酸杆菌的鉴定及病理组织观察

为了确定重庆地区仿生态养殖中华鳖(Pelodiscus sinensis)患病死亡的原因,从患病鳖的肠道分离得到一株优势菌PS01,对该菌进行了形态学观察、人工感染、生理生化特性测定、16S rRNA和gyrB基因序列分析、病理切片观察以及药敏试验。结果表明:人工感染中华鳖患病症状同自然发病症状;16S rRNA和gyrB序列构建的进化树表明,该菌与弗氏柠檬酸杆菌(Citrobacter freundii)同为一枝,相似性分别为99.7%、98.7%;病理组织观察发现,患病中华鳖的肝、脾、肾、胰和肠均有不同程度病变,其中以肠、肝脏、脾脏3个组织病变最为严重,肠绒毛大部分坏死脱落、肝细胞肿胀、胞核空泡化、脾脏红白髓混合分布、胰脏和肾脏轻度病变、胰腺细胞与肾小管上皮细胞肿大,其余组织未观察到明显变化。药敏试验表明,菌株PS01对多西环素等18种抗菌药物高度敏感,对氟苯尼考等3种抗菌药物中度敏感,对复方新诺明等18种抗菌药物表现为耐药。研究结果表明,弗氏柠檬酸杆菌为中华鳖的致病菌,其对30 g左右的中华鳖半致死浓度为9.3×10⁴ CPU·g^-1,有较强的致病性,可造成中华鳖多个组织病变。