马来西来番荔枝科紫玉盘属(Uvaria Linn.)、杯冠木属(Cyathostemma Griff.)和Ellipeia Hook.f.et Thomson叶的比较解剖学

对紫玉盘属8种,杯冠木属3种和Ellipeia属1种进行了叶的比较研究,以调查不同种之间解剖学的不同点,这对种的鉴别和了解它们的分类学意义可能是有用的.有意义的解剖学特征是末端石细胞,表皮细胞的晶簇,毛状体,在中脉和叶柄的薄壁组织内的短石细胞以及中脉和叶柄横切面的形状.有某些特征仅出现在某些种中,这对种的鉴别是有用的.结果亦显示这三个属的联系十分紧密.     

Medium optimization for chitinase production from Trichoderma virens using central composite design

Medium development for chitinase production by Trichoderma virens was first carried out using conventional method of one-factor-at-a-time. The medium was further optimized using Central Composite Design in which response surface was generated later from the derived model. An experimental design of four variables including various initial pH values, chitin, ammonium sulphate, and methanol concentrations were created using Design Expert® Software, Version 6.0. The design consists of 30 experiments, which include 6 replicates at center points. The optimal value for each variable are 3.0 g/L, chitin; 0.1 g/L, ammonium sulphate; 0.4% (v/v), methanol; and initial pH, 4.0 with predicted chitinase activity of 0.1495 U/mL. These predicted parameters were tested in the laboratory and the final chitinase activity obtained was 0.1471 U/mL, which is almost reaching the predicted value. The optimal medium design showed an improvement of chitinase activity of 80.9% compared to activity obtained from the original Absidia medium composition.     

Screening and identification of extracellular lipase-producing thermophilic bacteria from a Malaysian hot spring

Seven lipase-producing thermophilic bacteria (ST 1, ST 4, ST 6, ST 7, ST 8, ST 9 and ST 10) were isolated from the Setapak hot spring in Malaysia. The crude extracellular lipases recovered by ultrafiltration of cell-free culture supernatant were reacted in an olive oil mixture and their lipolytic activities were compared. Identification of the bacteria was carried out using the Biolog system and biochemical tests. Strain ST 7 that exhibited the highest lipolytic activity of 4.58 U/ml was identified as belonging to the Bacillus genus. Strain ST 6 with an activity of 3.51 U/ml, was identified as Ralstonia paucula. The lipolytic activities of strains ST 1, ST 4, ST 8, ST 9 and ST 10 were 2.39, 1.84, 2.38, 1.80 and 2.62 U/ml respectively. Strains ST 1, ST 4, and ST 10 were identified as Ralstonia paucula while strains ST 8 and ST 9 were Bacillus spp. Strains ST 7 and ST 9 were tentatively identified as Bacillus thermoglucosidasius, Bacillus stearothermophilus or Bacillus coagulans, whereas strain ST 8 was tentatively identified as Bacillus subtilis.     

Database and tools for metabolic network analysis

Metabolic network analysis has attracted much attention in the area of systems biology. It has a profound role in understanding the key features of organism metabolic networks and has been successfully applied in several fields of systems biology, including in silico gene knockouts, production yield improvement using engineered microbial strains, drug target identification, and phenotype prediction. A variety of metabolic network databases and tools have been developed in order to assist research in these fields. Databases that comprise biochemical data are normally integrated with the use of metabolic network analysis tools in order to give a more comprehensive result. This paper reviews and compares eight databases as well as twenty one recent tools. The aim of this review is to study the different types of tools in terms of the features and usability, as well as the databases in terms of the scope and data provided. These tools can be categorised into three main types: standalone tools; toolbox-based tools; and web-based tools. Furthermore, comparisons of the databases as well as the tools are also provided to help software developers and users gain a clearer insight and a better understanding of metabolic network analysis. Additionally, this review also helps to provide useful information that can be used as guidance in choosing tools and databases for a particular research interest.     

Light as a key driver of freshwater biofouling surface roughness in an experimental hydrocanal pipe rig

Biofouling in canals and pipelines used for hydroelectric power generation decreases the flow capacity of conduits. A pipeline rig was designed consisting of test sections of varying substrata (PVC, painted steel) and light levels (transparent, frosted, opaque). Stalk-forming diatoms were abundant in both the frosted and transparent PVC pipes but negligible in the painted steel and opaque PVC pipes. Fungi were slightly more abundant in the painted steel pipe but equally present in all the other pipes while bacterial diversity was similar in all pipes. Photosynthetically functional biofouling (mainly diatoms) was able to develop in near darkness. Different biological fouling compositions generated differing friction factors. The highest friction factor was observed in the transparent pipe (densest diatom fouling), the lowest peak friction for the opaque PVC pipe (lowest fouling biomass), and with the painted steel pipe (high fouling biomass, but composed of fungal and bacterial crusts) being intermediate between the opaque and frosted PVC pipes.     

Analysis of Comparative Sequence and Genomic Data to Verify Phylogenetic Relationship and Explore a New Subfamily of Bacterial Lipases

Thermostable and organic solvent-tolerant enzymes have significant potential in a wide range of synthetic reactions in industry due to their inherent stability at high temperatures and their ability to endure harsh organic solvents. In this study, a novel gene encoding a true lipase was isolated by construction of a genomic DNA library of thermophilic Aneurinibacillus thermoaerophilus strain HZ into Escherichia coli plasmid vector. Sequence analysis revealed that HZ lipase had 62% identity to putative lipase from Bacillus pseudomycoides. The closely characterized lipases to the HZ lipase gene are from thermostable Bacillus and Geobacillus lipases belonging to the subfamily I.5 with ≤ 57% identity. The amino acid sequence analysis of HZ lipase determined a conserved pentapeptide containing the active serine, GHSMG and a Ca²⁺-binding motif, GCYGSD in the enzyme. Protein structure modeling showed that HZ lipase consisted of an α/β hydrolase fold and a lid domain. Protein sequence alignment, conserved regions analysis, clustal distance matrix and amino acid composition illustrated differences between HZ lipase and other thermostable lipases. Phylogenetic analysis revealed that this lipase represented a new subfamily of family I of bacterial true lipases, classified as family I.9. The HZ lipase was expressed under promoter P_lac using IPTG and was characterized. The recombinant enzyme showed optimal activity at 65°C and retained ≥ 97% activity after incubation at 50°C for 1h. The HZ lipase was stable in various polar and non-polar organic solvents.     

Proteins involved in biophoton emission and flooding-stress responses in soybean under light and dark conditions

To know the molecular systems basically flooding conditions in soybean, biophoton emission measurements and proteomic analyses were carried out for flooding-stressed roots under light and dark conditions. Photon emission was analyzed using a photon counter. Gel-free quantitative proteomics were performed to identify significant changes proteins using the nano LC–MS along with SIEVE software. Biophoton emissions were significantly increased in both light and dark conditions after flooding stress, but gradually decreased with continued flooding exposure compared to the control plants. Among the 120 significantly identified proteins in the roots of soybean plants, 73 and 19 proteins were decreased and increased in the light condition, respectively, and 4 and 24 proteins were increased and decreased, respectively, in the dark condition. The proteins were mainly functionally grouped into cell organization, protein degradation/synthesis, and glycolysis. The highly abundant lactate/malate dehydrogenase proteins were decreased in flooding-stressed roots exposed to light, whereas the lysine ketoglutarate reductase/saccharopine dehydrogenase bifunctional enzyme was increased in both light and dark conditions. Notably, however, specific enzyme assays revealed that the activities of these enzymes and biophoton emission were sharply increased after 3 days of flooding stress. This finding suggests that the source of biophoton emission in roots might involve the chemical excitation of electron or proton through enzymatic or non-enzymatic oxidation and reduction reactions. Moreover, the lysine ketoglutarate reductase/saccharopine dehydrogenase bifunctional enzyme may play important roles in responses in flooding stress of soybean under the light condition and as a contributing factor to biophoton emission.