安徽发现腹侧颈部白化的几内亚长翼蝠

2006年10月24日,在安徽省六安市金寨县响洪甸水库附近的矿洞中捕捉到1只腹侧颈部白化的雌性几内亚长翼蝠(Miniopterus magnater:Chiroptera,Vespertilionidae),该只白化个体的体重、头体长、前臂长、胫骨长、后足长、尾长、耳长和耳宽分别为14.4g、50.1mm、48.2mm、20.7mm、9.3mm、51.2mm、10.7mm和8.8mm,均在正常个体数据范围之内。     

樟芝菌丝体的氨基酸成分分析

测定了樟芝发酵菌丝体中游离氨基酸和结合氨基酸的含量。结果表明,樟芝菌丝体中含有丰富的8种人体必需氨基酸、支链氨基酸和谷氨酸,其中8种必需氨基酸含量是FAO(联合国粮农组织)标准的5.55倍,而芳香族氨基酸的含量却很低。在测定过程中,由于采用了酸水解,菌丝体中的色氨酸被破坏,而其余17种氨基酸均被测出,含量极其丰富。尤其是支链氨基酸的含量远大于α-酪蛋白、卵蛋白和大豆球蛋白。     

Reagentless amperometric immunosensor for human chorionic gonadotrophin based on direct electrochemistry of horseradish peroxidase

A novel amperometric immunosensor for determination of human serum chorionic gonadotrophin (HCG) was constructed by immobilization of HCG with titania sol-gel on a glassy carbon electrode and the direct electrochemistry of horseradish peroxidase (HRP) labeled to HCG antibody (HRP-anti-HCG). The morphologies of the HCG membrane were characterized to be chemically clean, porous and homogeneous. HRP-anti-HCG was functionally conjugated with the immobilized HCG after incubation in phosphate buffer (PBS) containing HRP-anti-HCG. A direct electron transfer of HRP with a rate constant of 1.35+/-0.40 s(-1) was observed at the HRP-anti-HCG-HCG/titania sol-gel membrane modified electrode in 0.1 M PBS pH 7.0. With a competitive mechanism the differential pulse voltammetric peak current of the immobilized HRP decreased linearly with an increasing HCG concentration from 2.5 to 12.5 mIU/ml in the incubation solution. The HCG immunosensor showed a detection limit of 1.4 mIU/ml, a good accuracy and acceptable precision and reproducibility with an intra-assay CV of 4.7% at 5.0 mIU/ml and an inter-assay precision of 8.1% obtained at 10 mIU/ml. The biosensor displayed a good stability in a storage period of 30 days.     

Methylation protects miRNAs and siRNAs from a 3'-end uridylation activity in Arabidopsis

Small RNAs of 21-25 nucleotides (nt), including small interfering RNAs (siRNAs) and microRNAs (miRNAs), act as guide RNAs to silence target-gene expression in a sequence-specific manner. In addition to a Dicer homolog, DCL1, the biogenesis of miRNAs in Arabidopsis requires another protein, HEN1. miRNAs are reduced in abundance and increased in size in hen1 mutants. We found that HEN1 is a miRNA methyltransferase that adds a methyl group to the 3'-most nucleotide of miRNAs, but the role of miRNA methylation was unknown. Here, we show that siRNAs from sense transgenes, hairpin transgenes, and transposons or repeat sequences, as well as a new class of siRNAs known as trans-acting siRNAs, are also methylated in vivo by HEN1. In addition, we show that the size increase of small RNAs in the hen1-1 mutant is due to the addition of one to five U residues to the 3' ends of the small RNAs. Therefore, a novel uridylation activity targets the 3' ends of unmethylated miRNAs and siRNAs in hen1 mutants. We conclude that 3'-end methylation is a common step in miRNA and siRNA metabolism and likely protects the 3' ends of the small RNAs from the uridylation activity.     

扎龙湿地白鹤春季停歇地昼间行为时间分配及活动规律

在2004年4～5月,采用瞬时扫描取样法对扎龙国家级自然保护区林甸芦苇沼泽区的野生白鹤(Grusleucogeranus)在春季迁徙停歇地的昼间各种行为进行了研究。结果表明,在整个观察时期内白鹤各种行为具有较强的规律性,活动时间分配比例为:觅食31%、游走27%、静栖19%、警戒17%、修饰6%。白鹤觅食行为在一天中有两个高峰,分别为早晨和黄昏;游走行为基本上与觅食行为呈正相变化,并且几乎每个游走高峰及低潮相应地伴随着觅食的高峰和低潮;由于渔民清晨下苇塘收鱼和放牧,在5:30～6:30和6:30～7:30两个时间段警戒行为比例最高;静栖行为基本与游走及觅食行为呈负相关,对比发现,静栖行为比例低于觅食行为,与笼养鹤类的情况存在一定的差异,原因可能是食物丰富度影响了野生状态下行为的时间分配;修饰行为所占比例较小,是由于修饰行为是非主要行为,其发生是随机的。天气状况对白鹤数量变化有一定影响,阴雨和大风天气,白鹤数量明显减少,鹤群转移。与正常天气情况相比,阴雨和大风对白鹤觅食、静栖和游走行为时间分配影响显著(P阴雨=0·000<0·05,P大风=0·000<0·05),觅食时间缩短,游走行为减少,静栖时间变长。     

碳氮比和光强对小球藻合成虾青素的影响

本文研究了碳氮比和光强对小球藻Chlorella zofingiensis合成虾青素的影响。结果表明,随着碳氮比的增加,虾青素含量提高,但是过高的碳氮比限制藻细胞的生长,当碳氮比为133时,虾青素的产量最大,达到9.19mg／L。高光诱导在高碳氮比基础上进一步提高虾青素的含量及产量。200μmol／m^2.S光强在没有严重影响小球藻生长的同时,明显提高虾青素含量,最大虾青素产量达到12.52mg／L。文章对不同诱导条件下虾青素的合成机理以及利用异养自养相结合的方法提高虾青素产量的可能性进行了讨论。     

光敏掩蔽基团在化学生物学中的应用

光敏掩蔽基团技术是通过运用一种由光子控制的光敏化合物,在光子激发后,被该化合物掩蔽处于惰性状态的生物活性分子重新被激活、释放以调节生理功能的化学生物学研究方法,它对生命活动的控制具有实时、原位、精确、快速的优势。该文综述了不同光敏基团的结构与功能,包括硝基苄基类、香豆素类、喹啉类、吲哚类、硝基二苯并呋喃类等,它们通过掩蔽神经递质、钙离子、蛋白质、缩氨酸、核苷酸、遗传物质等重要的生理活性物质来高选择性地调控不同的生物学过程。     

Variation in the significant environmental factors affecting larval abundance of four major Chinese carp species: fish spawning response to the Three Gorges Dam

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