Lysionotus fengshanensis Yan Liu & D. X. Nong sp. nov. (Gesneriaceae) from Guangxi,China

Lysionotus fengshanensis Yan Liu & D. X. Nong, a new species of Gesneriaceae from Guangxi, China, is described and illustrated. Lysionotus fengshanensis is very similar to L. longipedunculatus (W. T. Wang) W. T. Wang, but differs by the peduncle being 2–4 cm long and purple, corolla campanulate, 2.5–3.0 cm long, 1.5–1.7 cm in diameter at the mouth, filaments slightly geniculate near the middle, apex of filaments with gland and staminodes 3.     

BenA3基因双元载体的初步构建及转化绿僵菌189的初步研究

用XholⅠ和SalⅠ分别双酶切植物表达载体pCAMB IA1300和含有目的基因的pMD19-T-BenA3,定向连接得到重组质粒pCAMB IA1300-BenA3,将其导入农杆菌AGL-1。经PCR鉴定后,得到可用于绿僵菌转化的农杆菌双元载体。采用的预培养时间、菌液浓度、共培养时间、乙酰丁香酮浓度的条件下,进行农杆菌介导绿僵菌的遗传转化,得到可以稳定性遗传的绿僵菌转化子,随机挑选转化子进行苯菌灵抗性基因的PCR扩增表明,绿僵菌转化子含有了苯菌灵抗性基因。该转化体系的建立,将有利于绿僵菌生防功能基因的克隆和作用机制的研究。     

Characterization of a novel β-thioglucosidase CpTGG1 in Carica papaya and its substrate-dependent and ascorbic acid-independent O-β-glucosidase activity

Plant thioglucosidases are the only known S-glycosidases in the large superfamily of glycosidases.These enzymes evolved more recently and are distributed mainly in Brassicales.Thioglucosidase research has focused mainly on the cruciferous crops due to their economic importance and cancer preventive benefits.In this study,we cloned a novel myrosinase gene,CpTGG1,from Carica papaya Linnaeus.and showed that it was expressed in the aboveground tissues in planta.The recombinant CpTGG1 expressed in Pichia pastoris catalyzed the hydrolysis of both sinigrin and glucotropaeolin(the only thioglucoside present in papaya),showing that CpTGG1 was indeed a functional myrosinase gene.Sequence alignment analysis indicated that CpTGG1 contained all the motifs conserved in functional myrosinases from crucifers,except for two aglycon-binding motifs,suggesting substrate priority variation of the non-cruciferous myrosinases.Using sinigrin as substrate,the apparent Km and Vmax values of recombinant CpTGG1 were 2.82 mM and 59.9 μmol min-1 mg protein-1,respectively.The Kcat IKm value was 23 s-1 mM-1.O-β-glucosidase activity towards a variety of substrates were tested,CpTGG1 displayed substrate-dependent and ascorbic acid-independent O-β-glucosidase activity towards 2-nitrophenyl-βD-glucopyranoside and 4-nitrophenyl-β-D-glucopyranoside,but was inactive towards glucovanillin and n-octyl-β-D-glucopyranoside.Phylogenetic analysis indicated CpTGG1 belongs to the MYR II subfamily of myrosinases.     

The Effects of Palmitate on Hepatic Insulin Resistance Are Mediated by NADPH Oxidase 3-derived Reactive Oxygen Species through JNK and p38MAPK Pathways

Elevated plasma free fatty acid (FFA) levels in obesity may play a pathogenic role in the development of insulin resistance. However, molecular mechanisms linking FFA to insulin resistance remain poorly understood. Oxidative stress acts as a link between FFA and hepatic insulin resistance. NADPH oxidase 3 (NOX3)-derived reactive oxygen species (ROS) may mediate the effect of TNF-α on hepatocytes, in particular the drop in cellular glycogen content. In the present study, we define the critical role of NOX3-derived ROS in insulin resistance in db/db mice and HepG2 cells treated with palmitate. The db/db mice displayed increased serum FFA levels, excess generation of ROS, and up-regulation of NOX3 expression, accompanied by increased lipid accumulation and impaired glycogen content in the liver. Similar results were obtained from palmitate-treated HepG2 cells. The exposure of palmitate elevated ROS production and NOX3 expression and, in turn, increased gluconeogenesis and reduced glycogen content in HepG2 cells. We found that palmitate induced hepatic insulin resistance through JNK and p38^MAPK pathways, which are rescued by siRNA-mediated NOX3 reduction. In conclusion, our data demonstrate a critical role of NOX3-derived ROS in palmitate-induced insulin resistance in hepatocytes, indicating that NOX3 is the predominant source of palmitate-induced ROS generation and that NOX3-derived ROS may drive palmitate-induced hepatic insulin resistance through JNK and p38^MAPK pathways.     

低龄儿童龋病牙菌斑的菌群结构分析

目的通过低龄龋齿儿童与口腔健康儿童的微生物组检测,探讨低龄儿童龋病牙菌斑的菌群组成特征。方法在深圳地区招募轻度龋齿、重度龋齿及口腔健康儿童共100名,采集其牙菌斑或健康牙齿表面微生物样本,采用MiSeq测序平台进行16S V4-V5区域的高通量测序。同时,通过生物信息分析方法,对低龄龋齿儿童的牙菌斑的微生物组成的特征进行挖掘分析。结果相对口腔健康儿童,重度龋齿患儿的牙菌斑微生物多样性增加,轻度龋齿患儿则减少,但变化不显著。门水平的优势菌主要为放线菌门、变形菌门及拟杆菌门,虽有相对丰度变化但差异无统计学意义。前10位的优势菌属中,轻度及重度龋齿儿童的最高丰度优势菌属为棒状杆菌属,重度龋齿儿童与健康儿童中的棒状杆菌丰度差异有统计学意义(t=-2.195 5, P=0.028 1)。健康儿童口腔的优势菌属包含了卟啉单胞菌属,但在轻度及重度龋齿儿童的优势菌属则替换为月形单胞菌属。种水平的菌群结构分析显示,前10位的优势菌丰度变化差异无统计学意义,而低丰度的致病菌如变异链球菌(H=27.302 1, P<0.000 1)、Atopobium parvulum(H=17.418 2, P=0.000 2)、栖牙普氏菌(H=10.598 9, P=0.005 0)、唾液普氏菌(H=10.035 0, P=0.006 6)等则在重度龋齿儿童中显著富集。结论低龄龋齿儿童的牙菌斑微生物结构发生了改变,部分口腔有害菌的丰度显著增加与龋病严重程度密切相关。