The influence of dietary fatty acid and fasting on the hepatic lipid metabolism of barramundi (Lates calcarifer)

For many fish species, dietary fish oil (FO) has been substituted with other oils such as poultry oil (PO) without affecting growth performance. However, in barramundi, the mechanisms by which fatty acid metabolism is regulated are poorly understood, and the effects of FO substitution are unknown. This study defined changes in the expression of genes controlling the metabolism of fatty acids in barramundi over a 24‐h time period after a single meal. From one to 12 h after a single feeding event, the expression of fatty acid synthesis genes in the liver was upregulated, while genes involved in the β‐oxidation showed minimal alteration. However, the expression of β‐oxidation genes was significantly correlated with the expression of genes regulating fatty acid synthesis. In a second experiment, the changes in liver fatty acid composition and gene expression were defined after FO was substituted with PO. Liver fatty acid profile reflected the diet composition, with some subtle exceptions supporting the enrichment of certain long‐chain polyunsaturated fatty acids in the liver. The fish from all experimental groups preferentially retained more docosahexaenoic acid than eicosapentaenoic acid in the liver, suggesting a bioconversion of this fatty acid to intermediate fatty acids. Replacement of FO with PO significantly regulated genes controlling both fatty acid synthesis and catabolism pathways, potentially related to a higher percentage of monounsaturated fatty acids, in the livers of fish fed these diets. The results demonstrated that diet composition significantly altered the lipid metabolism in barramundi and that there was a balance between direct dietary effects and endogenous synthetic capacity.     

Physiological metabolism of Haliotis discus hannai Ino under different light qualities and cycles

The goal of this experiment was to examine the effects of different light qualities (red, white, blue) and cycles (12L:12D, 8L:16D, 4L:20D, 0L:24D, 16L:8D) on the survival, growth, metabolism and antioxidant defence system of Haliotis discus hannai Ino. Under red and white light at 4L:20D, the body weight‐specific growth rate of abalones was significantly higher than that of the 0L:24D group (P < 0.05). At 16L:8D, succinate dehydrogenase activity decreased and lactate dehydrogenase and alanine aminotransferase activity and the lactic acid content significantly rose (P < 0.05) in the red and white light groups. Under blue light, reactive oxygen species and malondialdehyde content for each light cycle were significantly higher than those of the red and white groups (P < 0.05). Under blue, white and red light, total antioxidant capacity (T‐AOC), superoxide dismutase (SOD) activity, glutathione peroxidase (GP_X) activity and reduced glutathione (GSH) content gradually rose with increased duration of light exposure. Under red light, significant differences in these parameters were detected between the 4L:20D and 16L:8D groups (P < 0.05). Under blue and white light at 16L:8D, values of T‐AOC, SOD, GP_X activity and GSH content were significantly lower than those of the 12L:12D group (P < 0.05). Overall, these results indicate that red light at light cycles of 4L:20D and 8L:16D is optimal for the culture and production of H. discus hannai, as these conditions promoted food intake, growth and health maintenance as well as normal physiological metabolism of the organism.     

茄子反向温敏雄性不育系可溶性糖含量及相关基因表达分析

为揭示茄子反向温敏核雄性不育(rTGMS)发生与糖类代谢的关系,以茄子rTGMS系‘05ms’及温度不敏感系‘S63’为试材,对不育期和可育期的叶片及花蕾的可溶性糖含量进行比较,结果表明,‘05ms’在不育和可育时期叶片和花蕾中的可溶性糖含量均显著低于‘S63’;进一步对‘05ms’花蕾进行转录组测序及对其糖类代谢相关途径进行分析,发现差异表达基因主要富集在3个通路:淀粉和蔗糖代谢、糖酵解/糖异生和氨基糖和核苷酸糖代谢,其中淀粉和蔗糖代谢通路的差异基因最多且大部分在低温条件表达下调,主要影响了葡萄糖和半乳糖醛酸的合成。此结果初步揭示了茄子反向温敏雄性不育系中糖类代谢响应温度变化的特点,为茄子雄性不育杂交育种提供理论依据。     

两个褐飞虱海藻糖转运蛋白基因的结构及调控海藻糖代谢功能

【目的】海藻糖是昆虫中的主要血糖物质,在昆虫的发育及生理活动中发挥重要功能。其中,海藻糖转运蛋白（Tret）在将海藻糖从其生成组织（例如脂肪体）运输到其消耗组织的过程中起着重要作用。本研究通过分析褐飞虱（Nilaparvata lugens）两条Tret1的序列结构,进一步抑制NlTret1的表达,探讨这两个NlTret1在褐飞虱体内的生物学功能。【方法】以褐飞虱两条Tret1序列为研究对象,利用生物信息学技术分析其蛋白结构以及与其他昆虫之间的同源性。采用RNAi（RNA interference）技术将合成的外源dsRNA（double-stranded RNA）注射到实验室饲养褐飞虱种群体内,抑制其体内NlTret1的表达,分别在注射48 h后取材,抽取总RNA并用反转录试剂盒合成第一链cDNA,采用qRT-PCR（quantitative real-time PCR）技术检测dsNlTret1的干扰效果以及RNAi后褐飞虱体内海藻糖代谢通路中相关基因的表达,最后测定葡萄糖、海藻糖和糖原含量以及海藻糖酶活性。【结果】生物信息学分析表明,NlTret1-like X1和NlTret1-2 X1的开放阅读框长度分别为1 920和1 578 bp,分别编码639和525个氨基酸,预测蛋白分子量分别为69.29和58.71 kD,等电点分别为8.32和8.36;NlTret1-like X1和NlTret1-2 X1的二级结构主要包含螺旋和卷曲;保守结构域分析显示它们均属于MFS家族。进化分析结果显示,不同昆虫的Tret1蛋白具有较高的同源性,且褐飞虱与其他半翅目昆虫具有较近的亲缘关系;与注射dsGFP组相比,注射靶标基因的dsRNA后均能够显著沉默本基因的表达;褐飞虱体内糖原、葡萄糖在注射dsNlTret1-like X1和dsNlTret1-2 X1后,其含量均无显著变化,然而不同于注射dsNlTret1-2 X1组,在注射dsNlTret1-like X1后褐飞虱体内海藻糖含量极显著升高;干扰NlTret1-like X1 48 h后褐飞虱体内TPS1、TPS2、TRE1-1、TRE1-2和TRE2的表达均极显著下调;而干扰NlTret1-2 X1 48 h后褐飞虱体内TPS1、TPS2和TRE1-1的表达虽也极显著下降,但TRE1-2和TRE2极显著上调;在注射dsNlTret1-like X1后,试虫可溶性海藻糖酶和膜结合型海藻糖酶的活性均极显著降低,而在注射dsNlTret1-2 X1后无显著变化。【结论】褐飞虱的两个Tret1在不同组织间发挥着不同的功能,其中NlTret1-like X1在特异性转运海藻糖参与能量供应中起到更为显著的作用。研究结果有助于探索Tret1在昆虫或无脊椎动物中调控海藻糖代谢平衡的调节机制,可为将来通过调控血糖平衡来控制褐飞虱等害虫提供理论依据。     

涝渍对Bt棉棉蕾杀虫蛋白表达含量及氮代谢影响

以Bt棉常规种泗抗1号和杂交种泗抗3号为材料,于盛蕾期设计不同程度涝渍(土壤持水量为最大持水量的90%、100%,渍水2 cm)胁迫4 d以及土壤持水量为最大持水量90%逆境下持续胁迫24~120 h的试验,探讨棉蕾中Bt杀虫蛋白表达量变化及相关氮代谢生理机制。结果表明,土壤不同涝渍程度影响棉蕾Bt蛋白含量。土壤持水量为最大持水量的90%、100%和渍水2 cm处理胁迫后,常规种泗抗1号棉蕾中Bt蛋白含量分别下降36.5%、42.1%和51.4%,杂交种泗抗3号分别下降19.2%、57.2%和64.5%。90%的土壤持水量持续胁迫96 h使棉蕾Bt蛋白含量开始显著下降,泗抗1号和泗抗3号分别下降20.8%和17.6%。随着胁迫时间延长下降幅度增大。不同涝渍程度或水渍持续胁迫条件下,棉蕾中可溶性蛋白含量,硝酸还原酶(NR)、谷氨酸草酰乙酸转氨酶(GOT)、谷氨酸丙酮酸转氨酶(GPT)、谷氨酰胺合成酶(GS)和谷氨酸合成酶(GOGAT)活性下降,游离性氨基酸含量,肽酶、蛋白酶活性增加。说明涝渍逆境下,棉蕾中蛋白质合成能力下降、分解能力增强,引起可溶性蛋白包括Bt杀虫蛋白含量下降,导致棉蕾抗虫性下降。     

烟草氨基酸代谢及其调控机制

综述了植物氨同化以及烟草中苯丙氨酸代谢、脯氨酸代谢、美拉德反应及其与烟叶风味和品质关系的研究进展,并分析了环境因素对烟草氨基酸代谢的影响,为深入研究氨基酸对烟叶品质和风味影响的机制奠定了基础。