利用DNA片段测序方法探究枳属和富民枳的分类地位

富民枳(Poncirus polyandra)属于芸香科(Rutaceae)枳属(Poncirus Raf.)。自发表以来,分类地位一直备受争议,其中在Flora of China中认为富民枳为柑橘杂交种(Poncirus polyandra),把枳属归并于柑橘属(Citrus)。该研究选取枳属的富民枳、枳(Poncirus trifoliata)及柑橘属下8个种共10个种47个个体作为研究材料,以九里香(Murraya exotica)为外类群,利用3个叶绿体片段(trn L-trn F、trn S-trn G、rbc L)、ITS片段和1个单拷贝核基因(Chr 5)数据构建系统发育树,探究枳属和富民枳的分类地位。结果表明:基于3个叶绿体片段数据构建的最大似然树(ML)和贝叶斯树(BI)的拓扑结构基本一致,10个物种聚为两大分支,即柑橘属的8个物种聚为一大分支,富民枳和枳聚为另一大分支。其中,富民枳所有个体聚为一小单系分支,枳的所有个体聚为一小单系分支,支持枳属和富民枳独立存在。2个核DNA片段数据结果显示,枳属的两个种与柑橘属的8个物种聚在一个大分支里,无法确立枳属的单系地位,但富民枳的9个个体聚在一起,暗示富民枳在遗传上是一个独立的类群。综上研究认为,无论是叶绿体DNA数据还是核DNA数据均支持富民枳是一个独立的物种,但核DNA数据不支持枳属成立。     

白噪声对听觉脑干电反应(ABR)和耳蜗电图(ECochG)的影响

本文通过20例听力正常人和10例听力正常豚鼠研究了白噪声对耳蜗电图(ECochG)和听觉脑干电反应(ABR)的干涉作用。实验结果表明,白噪声比短声(信号)的声强级低30dB(SL)以上时,ECochG和ABR的振幅仅轻微减小。白噪声与短声的声强级相等时,ECochG与ABR的振幅和出现率会明显受到干涉而减小,甚至完全消失。但是,此时的耳蜗微音器电位(CM)并未观察到有明显的变化。这意味着白噪声对ECochG和ABR的干涉作用主要与围绕毛细胞基底部的突触产生的抑制密切相关。由于白噪声对ABR各波的干涉有些差异,所以认为这种抑制,可能既包括脑中抑制也包括侧方抑制。     

农业系统中磷肥残效及磷循环研究Ⅱ.磷及其他养分在作物体内分配

土壤P供应状况及作物生长好坏可明显影响高粱、玉米、大豆籽实及秸秆中的P浓度、P在籽实及秸秆中的分配比和形成单位籽实产量的P收获量。P供应充分,作物生长良好(产量高),籽实中的P浓度高,籽实P/秸秆P的分配比大,每形成单位籽实消费的P量高。     

农业生态系统养分循环再利用作物产量增益的地理分异

通过４个地点中长期田间试验联网比较获得以下结果,农业生态系统养分循环再利用的作物产量增益受气候的热量因素、化肥施用和养分循环再利用持续时间的长短等因素影响．在不施化肥情况下,保持０．８循环率养分循环再利用的平均粮食增产量自北向南分别是：温带黑龙江海伦２５３ｋｇ·ｈｍ－２（１０年平均）、暖温带辽宁沈阳１１２２ｋｇ·ｈｍ－２（６年）和喀左１３３２ｋｇ·ｈｍ－２（８年）、亚热带湖南桃源２８８４ｋｇ·ｈｍ－２（７年）;在施用ＮＰ化肥基础上保持养分循环再利用则分别为海伦２２５、沈阳６９４、喀左７８６、桃源１３２１ｋｇ·ｈｍ－２．循环回田的农家肥养分对作物增产有着明显的残效叠加作用,在施用ＮＰＫ化肥基础上保持养分循环再利用的作物增产率在试验期间的前３年平均为５％,后３年平均可上升至１４％．     

Structural determinants underlying constitutive dimerization of unoccupied human follitropin receptors

The human follitropin receptor (hFSHR) is a G protein-coupled receptor (GPCR) central to reproductive physiology that is composed of an extracellular domain (ECD) fused to a serpentine region. Using bioluminescence resonance energy transfer (BRET) in living cells, we show that hFSHR dimers form constitutively during their biosynthesis. Mutations in TM1 and TM4 had no effect on hFSHR dimerization, alone or when combined with mutation of Tyr¹¹⁰ in the ECD, a residue predicted to mediate dimerization of the soluble hormone-binding portion of the ECD complexed with FSH (Q. Fan and W. Hendrickson, Nature 433:269–277, 2005). Expressed individually, the serpentine region and a membrane-anchored form of the hFSHR ECD each exhibited homodimerization, suggesting that both domains contribute to dimerization of the full-length receptor. However, even in the context of only the membrane-anchored ECD, mutation of Tyr¹¹⁰ to alanine did not inhibit dimerization. The full-length hFSHR and the membrane-anchored ECD were then each engineered to introduce a consensus site for N-linked glycosylation at residue 110. Despite experimental validation of the presence of carbohydrate on residue 110, we failed to observe disruption of dimerization of either the full-length hFSHR or membrane-anchored ECD containing the inserted glycan wedge. Taken altogether, our data suggest that both the serpentine region and the ECD contribute to hFSHR dimerization and that the dimerization interface of the unoccupied hFSHR does not involve Tyr¹¹⁰ of the ECD.     

LOC100996425 acts as a promoter in prostate cancer by mediating hepatocyte nuclear factor 4A and the AMPK/mTOR pathway

The involvement of long non-coding RNAs (lncRNAs), differentially expressed genes and signals in prostate cancer (PCa) continues to be a subject of investigation. This study determined effects of LOC100996425 on human PCa by targeting hepatocyte nuclear factor 4A (HNF4A) via the AMPK/mTOR pathway. PCa and adjacent normal tissues were obtained to characterize expression pattern of LOC100996425, HNF4A and the AMPK/mTOR pathway-related genes. Then, the target gene of LOC100996425 was determined with lncRNA target prediction website and further verification was obtained through luciferase assay and ribonucleoprotein immunoprecipitation. After that, PCa cells were introduced with LOC100996425, HNF4A, siLOC100996425 or siHNF4A to explore the specific significance of LOC100996425 and HNF4A in PCa. The mechanism associated with AMPK/mTOR pathway was investigated using AMPK inhibitor or activator. LOC100996425 was up-regulated, while HNF4A was down-regulated in the PCa tissues. HNF4A was a target gene of LOC100996425. PCa cells transfected with either siLOC100996425 or HNF4A displayed reduced rates of PCa cell proliferation and migration while elevating cell apoptosis. HNF4A overexpression reversed the promotive effect of LOC100996425 overexpression on PCa. The activation of AMPK pathway involved in the cancer progression mediated by LOC100996425. Down-regulation of LOC100996425 retards progression of PCa through HNF4A-mediated AMPK/mTOR pathway.     

细菌分解代谢转座子研究

近年来 ,随着人工合成化学物质大量进入环境 ,现已在环境中发现了新的适应性的细菌对有机污染物的代谢机制。许多分解代谢基因与插入元件或转座子相连 ,因此 ,分解代谢基因可以在细菌间快速传播。这种快速传播有利于新的降解途径的产生。因此 ,这种代谢全能性可以被开发并在生物修复污染环境中起到关键作用     

The distribution,diversity, and conservation status of Cycas in China

As ancient gymnosperm and woody plants, cycads have survived through dramatic tectonic activities, climate fluctuation, and environmental variations making them of great significance in studying the origin and evolution of flora biodiversity. However, they are among the most threatened plant groups in the world. The principal aim of this review is to outline the distribution, diversity, and conservation status of Cycas in China and provide suggestions for conservation practices. In this review, we describe the taxonomy, distribution, and conservation status of Cycas in China. By comparing Chinese Cycas species with its relatives worldwide, we then discuss the current genetic diversity, genetic differentiation of Cycas, and try to disentangle the potential effects of Quaternary climate changes and topographical events on Cycas. We review conservation practices from both researchers and practitioners for these rare and endangered species. High genetic diversity at the species level and strong genetic differentiation within Cycas have been observed. Most Cycas species in southwest China have experienced population retreats in contrast to the coastal Cycas's expansion during the Quaternary glaciation. Additionally, human activities and habitat fragmentation have pushed these endangered taxa to the brink of extinction. Although numerous efforts have been made to mitigate threats to Cycas survival, implementation and compliance monitoring in protection zones are currently inadequate. We outline six proposals to strengthen conservation measures for Cycas in China and anticipate that these measures will provide guidelines for further research on population genetics as well as conservation biology of not only cycads but also other endangered species worldwide.     

Influence of Carbon Monoxide on Growth and Apoptosis of Human Umbilical Artery Smooth Muscle Cells and Vein Endothelial Cells

Carbon monoxide (CO) is a vasoactive molecule that is generated by vascular cells as a byproduct of heme catabolism and it plays an important physiological role in circulation system. In order to investigate whether exogenous CO can mediate the growth and proliferation of vascular cells, in this study, we used 250 parts per million (ppm) of CO to treat human umbilical artery smooth muscle cell (hUASMC) and human umbilical vein endothelial cell (HuVEC) and further evaluated the growth and apoptosis status of SMC and HuVEC. After SMC and HuVEC were exposed to CO for 7-day, the growth of SMC and HuVEC was significantly inhibited by CO in vitro on day 5 of CO exposure. And CO blocked cell cycle progress of SMC and HuVEC, more SMC and HuVEC stagnated at G0/G1 phase by flow cytometric analysis. Moreover, CO treatment inhibited SMC and HuVEC apoptosis caused by hydrogen peroxide through decreasing caspase 3 and 9 activities. To confirm the molecular mechanism of CO effect on SMC and HuVEC growth, we compared the gene expression profile in SMC and CO-treated SMC, HuVEC and CO-treated HuVEC. By microarray analysis, we found the expression level of some genes which are related to cell cycle regulation, cell growth and proliferation, and apoptosis were changed during CO exposure. We further identified that the down-regulated CDK2 contributed to arresting cell growth and the down-regulated Caspase 3 (CASP3) and Caspase 9 (CASP9) were associated with the inhibition of cell apoptosis. Therefore, CO exerts a certain growth arrest on SMC and HuVEC by inhibiting cell cycle transition from G0/G1 phase to S phase and has regulatory effect on cell apoptosis by regulating the expression of apoptosis-associated genes.     

WNK4 inhibits NCC protein expression through MAPK ERK1/2 signaling pathway

WNK [with no lysine (K)] kinase is a subfamily of serine/threonine kinases. Mutations in two members of this family (WNK1 and WNK4) cause pseudohypoaldosteronism type II featuring hypertension, hyperkalemia, and metabolic acidosis. WNK1 and WNK4 were shown to regulate sodium chloride cotransporter (NCC) activity through phosphorylating SPAK and OSR1. Previous studies including ours have also shown that WNK4 inhibits NCC function and its protein expression. A recent study reported that a phorbol ester inhibits NCC function via activation of extracellular signal-regulated kinase (ERK) 1/2 kinase. In the current study, we investigated whether WNK4 affects NCC via the MAPK ERK1/2 signaling pathway. We found that WNK4 increased ERK1/2 phosphorylation in a dose-dependent manner in mouse distal convoluted tubule (mDCT) cells, whereas WNK4 mutants with the PHA II mutations (E562K and R1185C) lost the ability to increase the ERK1/2 phosphorylation. Hypertonicity significantly increased ERK1/2 phosphorylation in mDCT cells. Knock-down of WNK4 expression by siRNA resulted in a decrease of ERK1/2 phosphorylation. We further showed that WNK4 knock-down significantly increases the cell surface and total NCC protein expressions and ERK1/2 knock-down also significantly increases cell surface and total NCC expression. These data suggest that WNK4 inhibits NCC through activating the MAPK ERK1/2 signaling pathway.