Members of a New Group of Chitinase-Like Genes are Expressed Preferentially in Cotton Cells with Secondary Walls

Two homologous cotton (Gossypium hirsutum L.) genes, GhCTL1 and GhCTL2, encode members of a new group of chitinase-like proteins (called the GhCTL group) that includes other proteins from two cotton species, Arabidopsis, rice, and pea. Members of the GhCTL group are assigned to family GH19 glycoside hydrolases along with numerous authentic chitinases (http://afmb.cnrs-mrs.fr/CAZY/index.html), but the proteins have novel consensus sequences in two regions that are essential for chitinase activity and that were previously thought to be conserved. Maximum parsimony phylogenetic analyses, as well as Neighbor-Joining distance analyses, of numerous chitinases confirmed that the GhCTL group is distinct. A molecular model of GhCTL2 (based on the three-dimensional structure of a barley chitinase) had changes in the catalytic site that are likely to abolish catalytic activity while retaining potential to bind chitin oligosaccharides. RNA blot analysis showed that members of the GhCTL group had preferential expression during secondary wall deposition in cotton lint fiber. Cotton transformed with a fusion of the GhCTL2 promoter to the beta -d-glucuronidase gene showed preferential reporter gene activity in numerous cells during secondary wall deposition. Together with evidence from other researchers that mutants in an Arabidopsis gene within the GhCTL group are cellulose-deficient with phenotypes indicative of altered primary cell walls, these data suggest that members of the GhCTL group of chitinase-like proteins are essential for cellulose synthesis in primary and secondary cell walls. However, the mechanism by which they act is more likely to involve binding of chitin oligosaccharides than catalysis.     

Regio- and stereo-selective synthesis of vinyl glucose ester catalyzed by an alkaline protease of Bacillus subtilis

The transesterification of -d-glucose with divinylsuccinate, divinyladipate and divinylsebacate in pyridine at 55 °C for 3 days was catalyzed by an alkaline protease from Bacillus subtilis to give corresponding 6-O-vinyl glucose esters at 30%, 53% and 35% yield, respectively. The stereo-selectivity of the alkaline protease toward the -anomer was affected by the acyl donor chain length. 6-O-Vinylsuccinyl-d-glucose was mixture of - and -anomers (/=44/56), the other two products were the pure -d-glucose derivatives.     

Facile synthesis of novel mutual derivatives of nucleosides and pyrimidines by regioselectively chemo-enzymatic protocol

We established a facile regioselectively chemo-enzymatic synthesis procedure for the preparation of mutual derivatives of nucleosides and pyrimidines by sequential Markovnikov addition and acylation. Firstly, pyrimidine derivatives containing vinyl ester group were synthesized from pyrimidines and divinyl esters through Markovnikov addition catalyzed by K₂CO₃ in DMSO at 80 °C, and the yields were ranged from 50% to 87%. Then regioselective acylation of ribavirin and cytarabine with pyrimidine vinyl ester was catalyzed by CAL-B (immobilized lipase from Candida antarctica) in anhydrous acetone. Reaction conditions of enzymatic acylation including enzyme resource and solvents were optimized. A series of mutual derivatives of nucleosides and pyrimidines were synthesized successfully and characterized with NMR, IR, and HRMS. This chemo-enzymatic protocol involving sequential Markovnikov addition and acylation provided a novel way of synthesizing complicated functional compounds regioselectively which was hard to be achieved either by chemical or by enzymatic methods.     

Modulating the synthetase activity of penicillin G acylase in organic media by addition of N-methylimidazole: using vinyl acetate as activated acyl donor

This paper reported the modulation of enzyme activity by organic small molecule. The esterification activity of Penicillin G acylase (PGA) was improved more than 70-fold by the addition of 10% N-methylimidazole. Some control experiments have been designed to demonstrate the catalytic specificity of PGA. The structure and the amount of additive were optimized to improve the product yield. The influence of N-methylimidazole on the PGA conformation was investigated by FTIR and autodock simulation. Seven substrates were used to evaluate the effect of structure on the PGA-catalyzed transesterification. A series of products were successfully synthesized with the yield ranged from 56% to 84% and PGA showed specific recognition on the substrate with phenyl group in the presence of 10% N-methylimidazole.     

一株尼古丁降解菌株Arthrobacter sp.D4的分离鉴定及其降解代谢途径

【背景】烟草在生产和加工中会产生高浓度的尼古丁废弃物,对环境造成较大的污染。【目的】筛选降解尼古丁的微生物菌种并解析其降解尼古丁的代谢途径,理解微生物如何降解尼古丁。【方法】用常规分离筛选方法、结合形态学观察和分子鉴定手段分离和鉴定菌株类别,进而利用单因素试验方法,通过设置不同的尼古丁浓度、温度和pH确定菌株降解尼古丁的最适发酵条件和降解率,利用气相色谱-质谱联用技术检测菌株在尼古丁降解过程中的主要代谢产物。【结果】获得一株以尼古丁为唯一碳源和氮源的节杆菌属(Arthrobacter)菌株,编号为D4;该菌株降解尼古丁的最适温度和pH分别为30.0℃和7.0;在1 g/L的尼古丁浓度下具备较快的尼古丁降解速率,培养18 h时尼古丁降解率可达到90%以上;尼古丁浓度≥4 g/L时菌株生长受到明显抑制;与目前报道的节杆菌属降解途径不同,该菌株降解尼古丁过程中产生了新的终产物N-甲基吡咯烷酮、可替宁及中间产物麦斯明。【结论】本研究分离鉴定到一株具有较快尼古丁降解速率的节杆菌,该菌株很可能存在新的尼古丁降解途径。     

双乙酰还原酶的分离纯化研究

比较了５种细菌、４种酵母菌和鸡肝中双乙酰还原酶含量,其中粪肠杆菌（Ｅｎｔｅｒｏ－ｃｏｃｃｕｓｆａｅｃａｌｉｓ）ＡＳ１．５９５中含量较高,为９．６ＩＵ／ｇ湿菌体。并对ＡＳ１．５９５菌酶和鸡肝酶进一步经ＳｅｐｈａｄｅｘＧ－１００和ＤＺＡＥ柱分离纯化,提纯倍数分别为４５、８９３,最后收率分别为１８．５％、５．１％。     

硫酸盐还原菌净化含铬电镀废水的中试研究

本文研究了硫酸盐还原菌在还原剂的参与下净化含铬电镀废水中间试验的工艺条件,通过净化措施,使废水中Cr(6 )含量由30～40mg／L,下降为0．1mg／L以下,达到了废水排放标准。去除率为99．67～99．97％。分批净化电镀废水103t,试验证明废水净化工艺具有良好的稳定性。而且消除了二次污染。     

党参的离体培养及植株再生的研究

在附加激素的MS培养基上,培养党参下胚轴和无菌芽切段,诱导产生愈伤组织并且再生植株。经过两年多(15个世代)的继代培养,建立了党参体细胞无性系。实验结果表明:(1)培养基MS 0.4mg/L 2,4-D 0.8mg/L Kt 2.0mg/L IAA对愈伤组织诱导及继代培养,MS 0.2mg/L 6-BA诱导外植体产生丛芽和愈伤组织再分化,MS 0.5mg/L NAA 0.2mg/L 6-BA及MS 0.2mg/L NAA诱导生根效果最好。(2)愈伤组织再分化经过胚状体途径。     

Enhancing the Thermotolerance of Isochrysis zhangjiangensis Through Co-culturing With Algoriphagus marincola

Marine Biotechnology - Isochrysis zhangjiangensis is an important microalgal species used as bait in aquaculture. However, its optimal cultivation temperature is around 25 °C,...     

Biotechnological improvement of cotton fibre maturity

This mini-review focuses on the prospects and tools for controlling cotton fibre secondary wall thickness. Cotton fibre secondary walls are composed of almost 100% cellulose, and are responsible for fibre maturity and a large component of fibre yield. Improved fibre yield and maturity would result from the ability to control secondary wall cellulose deposition quantitatively, including making the process less sensitive to environmental stress. Both genetic engineering and marker-assisted breeding are possible avenues for effecting such improvements, but first key genes that participate in the regulation and control of secondary wall cellulose biogenesis must be identified. Recent advances towards understanding and manipulating cotton fibre secondary wall deposition that are discussed here include: (i) experimental approaches to identify metabolic participants in cellulose biogenesis; (ii) isolation and characterization of promoters to drive foreign gene expression preferentially during secondary wall deposition; and (iii) a novel set of cDNA sequences representing genes that are differentially expressed during cotton fibre secondary wall deposition compared with primary wall deposition.