A new genus and species of freshwater monostiliferous hoplonemertean (Nemertea, Enopla) from the People's Republic of China

A new genus and species of freshwater monostiliferous hoplonemertean, Limnemertes poyangensis gen. et sp. nov., from Poyang Lake, People's Republic of China, is described and illustrated. The taxon is compared and contrasted with previously described freshwater hoplonemerteans. This is the fourth species of freshwater nemertean to be described from China and the first recorded from Poyang Lake.     

In vitro induction of multiple shoots and plant regeneration inVigna

Summary Cotyledonary nodes, excised cotyledons, and hypocotyl segments of six varieties ofVigna mungo andV. radiata have been tested for their morphogenic potential on media containing a range of hormonal combinations including benzyladenine, kinetin, thidiazuron (TDZ), and zeatin. Multiple shoots developed on cotyledonary node explants in all varieties tested on basal medium containing cytokinin. Presence of both the cotyledons, either full or half, resulted in a maximum number of shoots produced. Shoot bud regeneration was achieved via meristem formation on excised cotyledons on Murashige-skoog basal medium with B₅ vitamins supplemented with TDZ. Mature plants had normal phenotypes.V. mungo var. PS1 andV. radiata var. Pusa 105 were found to be the most responsive varieties for shoot regneration. The histology ofin vitro organogenesis was studied.     

一株沙门氏菌拮抗菌的筛选及其在污染土壤原位修复中的应用

利用无菌滤纸片平板法从沙门氏菌(Salmonella)污染土壤中筛选到一株有效拮抗沙门氏菌的细菌A45,通过形态学、革兰氏染色和16SrDNA序列同源性分析鉴定为产碱杆菌(Alcaligenes sp.)。温室土培试验和田间原位试验结果都发现,利用该菌株制备的沙门氏菌拮抗菌剂能显著降低土壤中沙门氏菌数量(P0.05),与对照相比土壤中沙门氏菌数量下降2-3个数量级,表明该拮抗细菌可应用于沙门氏菌污染土壤的修复。     

Genomic Analysis of the Mycoparasite Pestalotiopsis sp. PG52

Pestalotiopsis sp. is a mycoparasite of the plant pathogen Aecidium wenshanense. To further understand the mycoparasitism mechanism of Pestalotiopsis sp., we assembled and analyzed its genome. The genome of Pestalotiopsis sp. strain PG52 was assembled into 335 scaffolds and had a size of 58.01 Mb. A total of 20,023 predicted genes and proteins were annotated. This study compared PG52 with the mycoparasites Trichoderma harzianum, Trichoderma atroviride, and Trichoderma virens. This study reveals the entirely different mycoparasitism mechanism of Pestalotiopsis compared to Trichoderma and reveals this mycoparasite’s strong ability to produce secondary metabolites.     

Structure and characterization of amidase from Rhodococcus sp. N-771: Insight into the molecular mechanism of substrate recognition

In this study, we have structurally characterized the amidase of a nitrile-degrading bacterium, Rhodococcus sp. N-771 (RhAmidase). RhAmidase belongs to amidase signature (AS) family, a group of amidase families, and is responsible for the degradation of amides produced from nitriles by nitrile hydratase. Recombinant RhAmidase exists as a dimer of about 107 kDa. RhAmidase can hydrolyze acetamide, propionamide, acrylamide and benzamide with kcat/Km values of 1.14 ± 0.23 mM^− 1s^− 1, 4.54 ± 0.09 mM^− 1s^− 1, 0.087 ± 0.02 mM^− 1s^− 1 and 153.5 ± 7.1 mM^− 1s^− 1, respectively. The crystal structures of RhAmidase and its inactive mutant complex with benzamide (S195A/benzamide) were determined at resolutions of 2.17 Å and 2.32 Å, respectively. RhAmidase has three domains: an N-terminal α-helical domain, a small domain and a large domain. The N-terminal α-helical domain is not found in other AS family enzymes. This domain is involved in the formation of the dimer structure and, together with the small domain, forms a narrow substrate-binding tunnel. The large domain showed high structural similarities to those of other AS family enzymes. The Ser-cis Ser-Lys catalytic triad is located in the large domain. But the substrate-binding pocket of RhAmidase is relatively narrow, due to the presence of the helix α13 in the small domain. The hydrophobic residues from the small domain are involved in recognizing the substrate. The small domain likely participates in substrate recognition and is related to the difference of substrate specificities among the AS family amidases.     

湖北长阳上泥盆统一种石松植物

描述一种采自湖北上泥盆统弗拉阶黄家蹬组中的石松植物。该植物茎轴纤细。叶基纺锤形,螺旋排列。叶线形,叶缘具刺。具顶生的孢子叶球。其孢子叶匙状或披针形,边缘具刺。孢子囊呈圆形或椭圆形。植物茎具原生中柱。原生木质部呈小脊状位于中柱边缘。后生木质部管胞由梯纹分子组成,在加厚棒之间没有类似“威廉姆逊纹”的连接物。该植物与采自湖南中泥盆统基维特阶的Longostachys(Zhu,Huand Feng) Caiand Chen可比较。它们在茎轴、线形和具刺的叶、纺锤形和螺旋排列的叶基、匙状披针形的孢子叶,以及叶、叶基和孢子叶的度量等特征方面均非常相似。两者在解剖特征上存有差别,即当前植物不具次生木质部,不具髓,后生木质部加厚棒之间不具连接物。考虑到现有特征并不足以建立新属种,暂归入cf.Longostachyssp.     

Crystal structures of beta-galactosidase from Penicillium sp. and its complex with galactose

Beta-galactosidases catalyze the hydrolysis of beta(1-3) and beta(1-4) galactosyl bonds in oligosaccharides as well as the inverse reaction of enzymatic condensation and transglycosylation. Here we report the crystallographic structures of Penicillium sp. beta-galactosidase and its complex with galactose solved by the SIRAS quick cryo-soaking technique at 1.90 A and 2.10 A resolution, respectively. The amino acid sequence of this 120 kDa protein was first assigned putatively on the basis of inspection of the experimental electron density maps and then determined by nucleotide sequence analysis. Primary structure alignments reveal that Penicillium sp. beta-galactosidase belongs to family 35 of glycosyl hydrolases (GHF-35). This model is the first 3D structure for a member of GHF-35. Five distinct domains which comprise the structure are assembled in a way previously unobserved for beta-galactosidases. Superposition of this complex with other beta-galactosidase complexes from several hydrolase families allowed the identification of residue Glu200 as the proton donor and residue Glu299 as the nucleophile involved in catalysis. Penicillium sp. beta-galactosidase is a glycoprotein containing seven N-linked oligosaccharide chains and is the only structure of a glycosylated beta-galactosidase described to date.     

克雷伯氏菌甘油脱氢酶dhaD的克隆表达、纯化及酶学性质研究

以克雷伯氏菌基因组DNA为模板,扩增得到编码甘油脱氢酶（GDH）的基因dhaD,将其克隆到大肠杆菌表达载体pET-28a(+)上,在E.coliBL21（DE3）中诱导表达,利用表达载体pET-28a(+)上的6·His-Tag标记选用Ni柱亲和层析法纯化表达具有活性的甘油脱氢酶(GDH),纯化后比酶活达到156U/mg,纯化倍数达4.6倍,回收率为67.4%。并初步研究了该酶的酶学性质,酶反应的最适pH为11.0,在pH7.0～12.0范围内稳定;酶反应的最适温度为30℃,稳定范围为25～45℃; 酶动力学参数以甘油为底物的Km为0.54 mmol/L, Vmax为0.49 μmol/(mL·min)。     

Xenoestrogenic short ethoxy chain nonylphenol is oxidized by a flavoprotein alcohol dehydrogenase from <Emphasis Type="Italic">Ensifer</Emphasis> sp. strain AS08

The ethoxy chains of short ethoxy chain nonylphenol (NPEO_av2.0, containing average 2.0 ethoxy units) were dehydrogenated by cell-free extracts from Ensifer sp. strain AS08 grown on a basal medium supplemented with NPEO_av2.0. The reaction was coupled with the reduction in 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and phenazine methosulfate. The enzyme (NPEO_av2.0 dehydrogenase; NPEO-DH) was purified to homogeneity with a yield of 20% and a 56-fold increase in specific activity. The molecular mass of the native enzyme was 120 kDa, consisting of two identical monomer units (60 kDa). The gene encoding NPEO-DH was cloned, which consisted of 1,659 bp, corresponding to a protein of 553 amino acid residues. The deduced amino acid sequence agreed with the N-terminal amino acid sequence of the purified NPEO-DH. The presence of a flavin adenine dinucleotide (FAD)-binding motif and glucose–methanol–choline (GMC) oxidoreductase signature motifs strongly suggested that the enzyme belongs to the GMC oxidoreductase family. The protein exhibited homology (40–45% identity) with several polyethylene glycol dehydrogenases (PEG-DHs) of this family, but the identity was lower than those (approximately 58%) among known PEG-DHs. The substrate-binding domain was more hydrophobic compared with those of glucose oxidase and PEG-DHs. The recombinant protein had the same molecular mass as the purified NPEO-DH and dehydrogenated PEG400-2000, NPEO_av2.0 and its components, and NPEOav10, but only slight or no activity was found using diethylene glycol, triethylene glycol, and PEG200. English edition: The paper was edited by a native speaker through American Journal Experts ().     

Biodegradation and detoxification of nicotine in tobacco solid waste by a Pseudomonas sp.

A Pseudomonas sp. grew with nicotine optimally 3 g l^–1 and at 30 °C and pH 7. Nicotine was fully degraded within 10 h. The resting cells degraded nicotine in tobacco solid waste completely within 6 h in 0.02 m sodium phosphate buffer (pH 7) at maximally 56 mg nicotine h^–1 g dry cell^–1.