A novel method of producing the pharmaceutical intermediate (R)-2-chloromandelic acid by bioconversion

(R)-2-Chloromandelic acid (R­CM) is one of the chiral building blocks used in the pharmaceutical industry. As a result of screening for microorganisms that asymmetrically hydrolyze racemic 2­chloromandelic acid methyl ester (CMM), Exophiala dermatitidis NBRC6857 was found to produce R­CM at optical purity of 97% ee. The esterase that produces R­CM, EstE, was purified from E. dermatitidis NBRC6857, and the optimal temperature and pH of EstE were 30°C and 7.0, respectively. The estE gene that encodes EstE was isolated and overexpressed in Escherichia coli JM109. The activity of recombinant E. coli JM109 cells overexpressing estE was 553 times higher than that of E. dermatitidis NBRC6857. R­CM was produced at conversion rate of 49% and at optical purity of 97% ee from 10% CMM with 0.45 mg-dry-cell/L recombinant E. coli JM109 cells. Based on these findings, R­CM production by bioconversion of CMM may be of interest for future industrial applications.     

Did the house mouse (Mus musculus L.) shape the evolutionary trajectory of wheat (Triticum aestivum L.)?

Wheat (Triticum aestivum L.) is one of the most successful domesticated plant species in the world. The majority of wheat carries mutations in the Puroindoline genes that result in a hard kernel phenotype. An evolutionary explanation, or selective advantage, for the spread and persistence of these hard kernel mutations has yet to be established. Here, we demonstrate that the house mouse (Mus musculus L.) exerts a pronounced feeding preference for soft over hard kernels. When allele frequencies ranged from 0.5 to 0.009, mouse predation increased the hard allele frequency as much as 10‐fold. Studies involving a single hard kernel mixed with ~1000 soft kernels failed to recover the mutant kernel. Nevertheless, the study clearly demonstrates that the house mouse could have played a role in the evolution of wheat, and therefore the cultural trajectory of humankind.     

草菇乙酰木聚糖酯酶的生物信息学分析

以草菇（Volvariella volvacea）乙酰木聚糖酯酶AXE、AXEII为研究对象,采用生物信息学方法对其核苷酸及编码的蛋白氨基酸序列、组成成分、信号肽、跨膜结构域、疏水性/亲水性、蛋白质三级结构等进行预测和分析,并构建了乙酰木聚糖酯酶蛋白家族的系统进化树。结果表明,草菇的AXE蛋白由349个氨基酸残基组成,编码蛋白质的分子量为37.55 ku,等电点为8.58,属稳定性蛋白质。AXEII由253个氨基酸残基组成,编码蛋白质的分子量为27.70 ku,等电点为5.82,属稳定性蛋白质。两者均为亲水性蛋白,存在信号肽,AXE与AXEII的潜在磷酸化位点总数分别为15个和11个。草菇的AXE与灰盖鬼伞（Coprinopsis cinerea）亲缘关系较近,AXEII与裂褶菌（Schizophyllum commune）亲缘关系较近。     

Differences in esterase isozymes between Panonychus citri populations infesting citrus and Osmanthus

Gene frequencies were investigated in the -Est1 locus between Japanese populations of Panonychus citri occurring on some fruit trees and on the garden trees, Osmanthus trees and Ilex crenata. A new allele, A ₃, was found in the -Est1 of populations collected on Osmanthus trees. Populations on I. crenata, Citrus unshiu and Pyrus serotina had one or both A ₁ and A ₂ alleles. However, the populations on Osmanthus trees had only the A ₃ allele and did not vary geographically.     

Enhancement of acetyl xylan esterase activity on cellulose acetate through fusion to a family 3 cellulose binding module

The current study investigates the potential to increase the activity of a family 1 carbohydrate esterase on cellulose acetate through fusion to a family 3 carbohydrate binding module (CBM). Specifically, CtCBM3 from Clostridium thermocellum was fused to the carboxyl terminus of the acetyl xylan esterase (AnAXE) from Aspergillus nidulans, and active forms of both AnAXE and AnAXE–CtCBM3 were produced in Pichia pastoris. CtCBM3 fusion had negligible impact on the thermostability or regioselectivity of AnAXE; activities towards acetylated corncob xylan, 4-methylumbelliferyl acetate, p-nitrophenyl acetate, and cellobiose octaacetate were also unchanged. By contrast, the activity of AnAXE–CtCBM3 on cellulose acetate increased by two to four times over 24 h, with greater differences observed at earlier time points. Binding studies using microcrystalline cellulose (Avicel) and a commercial source of cellulose acetate confirmed functional production of the CtCBM3 domain; affinity gel electrophoresis using acetylated xylan also verified the selectivity of CtCBM3 binding to cellulose. Notably, gains in enzyme activity on cellulose acetate appeared to exceed gains in substrate binding, suggesting that fusion to CtCBM3 increases functional associations between the enzyme and insoluble, high molecular weight cellulosic substrates.     

普通小麦-冰草6P染色体中间插入易位系的鉴定

远缘杂交技术是将小麦野生近缘植物的染色体片段导入小麦的有效途径。通过这种方法可以拓宽小麦的遗传基础,导入携带控制优异性状的基因从而达到改良小麦的目的。为了获得在小麦遗传及育种中具有较高研究利用价值的纯合的小麦-冰草小片段异源染色体易位系,我们利用细胞学手段对普通小麦-冰草的远缘杂交后代进行鉴定。本研究以小麦-冰草二体代换系4844-8、二体附加系4844-12与普通小麦杂交后辐照产生的易位系为材料,利用基因组原位杂交（GISH）技术从中鉴定出了2个具有冰草染色体小片段的纯合中间插入易位系。其中1个纯合中间插入易位系（104-3）具有高抗小麦白粉病和高千粒重的特性。另1个纯合中间插入易位系（19-2）具有较高的穗粒数和较高的千粒重的特性。本研究鉴定出的2个小麦-冰草6P小片段纯合中间插入易位系的优异农艺性状表明,它们是丰富小麦基因资源的优异的遗传材料,具有很高的研究利用价值。     

对家鸡血清酯酶发育调控的初步研究

采用垂直平板聚丙烯酰胺凝胶电泳方法跟踪测定了 １０ 羽优黄 ３８０ 商品蛋鸡血清酯酶的遗传表现型,结果表明：血清酯酶（ Ｅｓ１）的遗传表达具有明显的发育阶段差异性,开产前均为有带类型,并表现出遗传多态现象,开产后 Ｅｓ１ 酶带消失,表现为无活性 Ｏ 型⒚对 Ｉ Ｓ Ａ Ｂ３８０ 父母代 Ｃ Ｄ 母鸡的扩大抽样测定结果验证了上述的结论⒚由此我们推测,母鸡产蛋期 Ｅｓ１ 区无活性“ Ｏ 型”可能是基因表达在不同发育阶段调控（抑制）的结果,因此不存在“ Ｅｓ１基因座位上决定 Ｏ 型的等位基因 Ｅｓ１ｏ ⒚ Ｅｓ１ 基因在开产前处于转录活跃状态,开产后基因转录就被抑制,以维持产蛋期母鸡体内所需较高的血脂水平⒚母鸡血清酯酶表达发育遗传学规律可能广泛存在于家禽各种群体之中⒚如果该推测成立的话,家鸡酯酶的生物合成就可能成为研究禽类基因表达和调控的理想模型⒚     

Stability and catalytic properties of chemically modified pig trypsin

Pig trypsin was chemically modified with the bifunctional compound ethylene glycol-bis(succinic acid N-hydroxysuccinimide ester) to yield EG-trypsin. EG-trypsin showed greater thermal stability (100% active beyond 100 min at 55°C; native only 53% active at 100 min) together with slightly increased tolerance toward some organic solvents. Arg/Lys hydrolysis ratio changed little. Esterase/amidase activity ratio of EG-trypsin in buffer was 11-fold greater than that of native pig trypsin, but 5-fold less in 30% v/v acetonitrile. In buffer, EG-trypsin synthesized the dipeptide benzoyl-Arg-Leu-NH₂ at a 3-fold higher rate than native trypsin, but native trypsin outperformed EG-trypsin in 30% v/v acetonitrile.     

不同育秧方式和插植密度下早籼稻群体动态结构的研究

于1996年早季研究了湿润与旱育秧方式在稀植(2苗/科)和多植(4苗/科)情况下超高产早籼品种特三矮2号在本田生长期的群体动态结构与产量表现。与多植比较,稀植的比叶重较大,中期叶面积系数较小,每穗颖花数较多;但有效分蘖数较少。与湿润育秧比较,旱育秧每科穗数较多,抽穗后群体保持较高的叶面积系数和干物质生产力;但生育期较长。旱育稀植的谷草比较高。     

Catalytic role of conserved HQGE motif in the CE6 carbohydrate esterase family

An acetylxylan esterase (R.44), belonging to the carbohydrate esterase family 6 (CE6), retrieved from bovine rumen metagenome was analyzed. Molecular modelling and site-directed mutagenesis indicated that the enzyme possesses a catalytic triad formed by Ser(14), His(231) and Glu(152). The catalytic Ser and His have been identified in highly conserved sequences GQSX and DXXH in the CE6 family, respectively, and the active-site glutamate was part of a highly conserved sequence HQGE. This motif is situated near to the so-called Block III in the CE6 family and its role in catalysis has not been identified so far.