Expression Profiles and Response to Exogenous Hormones of β-Fructofuranosidase Gene BmSuc1 in Silkworms(Bombyx mori)

[Objectives]In order to clarify the regulatory effects of insect hormones on the expression of BmSuc1 and provide a reference for further analysis of the function and expression regulation mechanism of BmSuc1,this study explored the expression profiles of BmSuc1 in different tissues and periods of silkworm larvae and the expression changes of BmSuc1 after treatment with exogenous hormones.[Methods]By using the real-time fluorescence quantitative PCR technique,the expression characteristics of BmSuc1 were detected in different periods,different tissues and after treatment with exogenous hormones during the development of silkworm larvae.The expression of BmSuc1 and 20E receptor gene USP was detected after RNA interference with double-stranded RNA(dsRNA)of USP.[Results]The relative expression of BmSuc1 gene in the midgut was the highest,followed by the silk glands,epidermis and hemolymph.However,there was much lower or almost no expression in other tissues.In addition,the BmSuc1 expression profile exhibited a pulse-like pattern in silkworm larvae.The expression level of BmSuc1 was higher at each instar stage before molting,late fifth instar before cocooning and prepupal stage.Silkworm larvae at day 2 of the fifth instar were treated with 20-hydroxyecdysone(20E)and juvenile hormone(JH).It was found that the expression of BmSuc1 was extremely significantly higher at 12 and 18 h after 20E treatment than the control group injected with 0.1%dimethyl sulfoxide(DMSO)(P<0.01,the same below).But there were no significant difference in BmSuc1 expression between the JH treatment and the control group during the measurement time range(P>0.05).The dsRNA of USP was synthesized in vitro and injected into silkworm larvae at day 3 of the fifth instar.It was showed that the USP relative expression was extremely significantly down-regulated at 24 and 36 h after injection,which indicated that dsRNA interference was successful.RNAi of USP would block 20E signal transduction,and the expression of BmSuc1 was inhibited and significantly down-regulated at 24 and 36 h after injection of dsRNA of USP(P<0.05).[Conclusions]The BmSuc1 expression peaks appeared in the molting of silkworm larvae and the metamorphosis of larvae to pupae,which suggests that BmSuc1 may be involved in the metamorphic development process of silkworms.Treatment with exogenous ecdysone 20E can activate the expression of BmSuc1,but blocking the 20E signal transduction pathway may suppress expression of BmSuc1.It indicates that BmSuc1 as a downstream target gene in the 20E signal transduction pathway is directly or indirectly regulated by 20E signals.

Differential accumulation mechanisms of purine alkaloids and catechins in Camellia ptilophylla,a natural theobromine-rich tea

Tea is consumed worldwide due to its charming flavor and the refreshing effects conferred by caffeine.Caffeine however has undesirable side effects,such as sleep disturbance.Camellia ptilophylla is known for its low caffeine content,and the biosynthesis of purine alkaloids in this species has become a hot topic.In this study,the accumulation of purine alkaloids in a natural C.ptilophylla population(32 plants)was analyzed,and the results showed that 81.25%of this population were caffeine-free,containing only theobromine(TB),while six plants contained both theobromine and caffeine(CAF).RNA-seq analysis of two C.ptilophylla plants with contrasting purine alkaloid contents(TB and CAF)revealed that xanthosine synthesis genes of the SAM cycle and AMP pathway were significantly related to the differential accumulation of purine alkaloids between TB and CAF.The high theobromine content in TB was attributed to the significantly higher expression of TCS-2,TCS-3 and MXMTs and downregulation of the xanthosine degradation pathway in comparison to CAF.Additionally,CsMYB184 was significantly upregulated in TB,opposing the expression pattern of TCS1,but consistent with that of other TCSs and MXMTs.Furthermore,the upregulated expression of catechin biosynthesis genes,F3'H,F3'5'H and SCPLs in TB corresponded to a higher gallocatechin gallate(GCG)content.Overall,these findings provide new insights into the accumulation of theobromine and GCG,which may facilitate the development of tea plant cultivars with low-caffeine or high GCG to meet the diverse demands of consumers.

用于生物医学应用的基于微藻的生物杂化材料的合理设计和开发

微藻是一种体积微小的真核生物,可通过叶绿素a的光合作用将二氧化碳转化为多种生物活性物质。在过去的十年中,有关活体微藻和其他生物相容性成分组成的生物杂化材料在解决许多医学难题中显示出巨大的潜力,如肿瘤治疗、组织重建和药物输送。固定在常规生物材料中的微藻可以长时间维持其光合活性从而在局部提供氧气,同时也可作为调节细胞活性的生物相容性界面材料。微藻的运动性还激发了生物杂交机器人的发展,其中药物分子可通过非共价键吸附结合至微藻表面,并通过精确控制其运动轨迹将药物输送到目标区域。此外,微藻的自发荧光、趋光性和生物质生产可以整合到具有多种功能的新型生物杂化材料的设计中;通过基因工程改造的微藻可以赋予生物杂交材料新的特性,如特异性细胞靶向能力和从藻类细胞中局部释放重组蛋白——这些技术技术有望促进微藻基生物杂交材料(MBBM)在多个生物医学领域的临床应用。本文总结了MBBM的制造、生理学和运动能力;然后,回顾了MBBM近年来在生物医学领域的典型应用报告;最后,对MBBM的挑战和未来前景进行了讨论。