三七重茬根际土壤中化感物质的测定及其对三七根腐菌的生长作用

目的 研究三七重茬根际土壤中化感物质的组成及其对病原微生物的化感作用。方法 采用乙酸乙酯提取三七重茬根际土壤中的化感物质,利用GC-MS对萃取液进行物质组成分析,并研究检测中出现的特征性化感物质对羟基苯甲酸、邻苯二甲酸二异丁酯对三七根腐病菌（F.oxysporum Schlecht）的化感作用。结果 采集的三七重茬土壤中共检测到29种化感物质,其中2种特征性化感物质对羟基苯甲酸、邻苯二甲酸二异丁酯对三七病原菌的生长呈现低促高抑的现象,且当对羟基苯甲酸浓度为5 mmol/L时能促进病菌小孢子的产生。结论 检测到的化感物质组分为苯甲酸及其衍生物类、酚类、酯类、饱和烃类等物质。这些物质在低浓度时有利于病原菌的生长,对病害的发生具有促进作用。     

Synthesis and biological evaluation of benzo[4,5]imidazo[1,2-c]pyrimidine and benzo[4,5]imidazo[1,2-a]pyrazine derivatives as anaplastic lymphoma kinase inhibitors

Chromosomal translocations involving anaplastic lymphoma kinase (ALK) are the driving mutations for a range of cancers and ALK is thus considered an attractive therapeutic target. We synthesized a series of functionalized benzo[4,5]imidazo[1,2-c]pyrimidines and benzo[4,5]imidazo[1,2-a]pyrazines by an aza-Graebe–Ullman reaction, followed by palladium-catalyzed cross-coupling reactions. A sequential regioselective cross-coupling route is reported for the synthesis of unsymmetrically disubstituted benzo[4,5]imidazo[1,2-a]pyrazines. The inhibition of ALK was evaluated and compound 19 in particular showed good activity against both the wild type and crizotinib-resistant L1196M mutant in vitro and in ALK-transfected BaF3 cells.     

Circadian effect of ACTH 1-17 on mitotic index of the corneal epithelium of BALB/C mice

The objective was to determine the effect of ACTH 1-17, an adrenocorticotropin analogue, on the mitotic index in the corneal epithelium of mice standardized in 12 hr of light alternating with 12 hr darkness. A question asked was whether the time of administration along the 24-hr time scale influenced any response found. The findings showed that ACTH 1-17 could, depending upon when it was administered, bring about a statistically significant decrease, an increase or even no such change in the mitotic index. The greatest responses found were increases, especially when ACTH 1-17 was administered during the dark span. Also the time after injection when the responses occurred varied. The greatest response recorded was at 12 hr after injection when ACTH 1-17 was given at 2 hr into the dark with a 641% and a 718% increase with a low (0.02 IU/kg) and a higher (20 IU/kg) dose, respectively. A 3-way analysis of variance supported the conclusion that the kind-of-treatment, time-of-treatment and treatment-to-kill interval (sampling time) are important factors when determining any response to ACTH 1-17 on the mitotic index.     

Isozyme analysis of intercontinental disjuncts within Styrax (Styracaceae): implications for the Madrean —Tethyan hypothesis

Various hypotheses have been put forward to explain the presence of sclerophyllous plant disjuncts between western North America and the Mediterranean region. The Madrean–Tethyan hypothesis postulates that the two regions were floristically connected in the Early to Middle Tertiary by way of a low-latitude migration route. Others deny the possibility of such a route, and instead postulate convergence to xerophytic conditions from more widespread mesophytic ancestors, or suggest long-distance dispersal scenarios. One example of a “Madrean–Tethyan link” between the two regions is composed of four species within the genus Styrax: S. officinalis subsp. officinalis from the Mediterranean region, S. officinalis subsp. redivivus and subsp. fulvescens from California, and three closely related species in Texas and northeastern Mexico (S. texanus, S. platanifolius, and S. youngiae). This group was examined with isozymes to assess whether patterns of genetic variation are consistent with those predicted by the Madrean–Tethyan hypothesis. Ten populations from California, six from the Mediterranean region, and three from Texas were sampled. Pairwise comparisons revealed mean genetic identity (I) estimates of 0.581 between Mediterranean and California populations, 0.470 between Mediterranean and Texas populations, and 0.640 between California and Texas populations. Two populations of a species thought by many to be the closest relative of S. officinalis on morphological grounds (S. jaliscanus) exhibited low I (0.299–0.321) relative to all other group comparisons. Intercontinentally disjunct populations of S. officinalis possessed an I value that warrants species status for the Californian and Mediterranean groups. Divergence time estimates between Madrean and Tethyan Styrax range from 5.0 to 13.8 Mya, too recent to be consistent with the Madrean–Tethyan hypothesis. However, alternative explanations for this disjunction are suboptimal in that they require the invocation of either long-distance dispersal, which appears unlikely in this group, or extinction. Nonetheless, the evidence presented here and in other recent studies casts substantial doubt on the Madrean–Tethyan hypothesis as a general explanation for the presence of Madrean and Tethyan taxa similar in overall appearance. More plants with Madrean–Tethyan distributions must be sampled before definitive conclusions regarding this aspect of Madrean and Tethyan vegetation can be reached.     

Programming microbial population dynamics by engineered cell-cell communication

A major aim of synthetic biology is to program novel cellular behavior using engineered gene circuits. Early endeavors focused on building simple circuits that fulfill simple functions, such as logic gates, bistable toggle switches, and oscillators. These gene circuits have primarily focused on single-cell behaviors since they operate intracellularly. Thus, they are often susceptible to cell-cell variations due to stochastic gene expression. Cell-cell communication offers an efficient strategy to coordinate cellular behavior at the population level. To this end, we review recent advances in engineering cell-cell communication to achieve reliable population dynamics, spanning from communication within single species to multispecies, from one-way sender-receiver communication to two-way communication in synthetic microbial ecosystems. These engineered systems serve as well-defined model systems to better understand design principles of their naturally occurring counterparts and to facilitate novel biotechnology applications.     

Synthesis of phosphatidylglycerol by chloroplasts from leaves of Spinacia oleracea L. (spinach)

Purified chloroplasts from leaves of Spinacia oleracea L. (spinach) incorporated glycerol 3-phosphate into diacylglycerol, monoacylglycerol, phosphatidylglycerol, phosphatidic acid, and lysophosphatidic acid. The omission of ATP or CTP, CoA or illumination decreased the incorporation markedly. The fraction of incorporated glycerol 3-phosphate found in phosphatidylglycerol was greatly reduced by the omission of bicarbonate, acetate, and ATP, or in darkness, low-osmolarity medium, or high magnesium ion concentration (10 mM). Incorporation of glycerol 3-phosphate into lipid and specifically into phosphatidylglycerol was optimal at a $\text{Mg}{}^{\mathrm{2+}}\text{CTP}$ ratio of 1, whereas the optimal ratio for $\text{Mg}{}^{\mathrm{2+}}\text{ATP}$ was closer to 2. The $\text{Mg}{}^{\mathrm{2+}}\text{CTP}$ gave lower total incorporation but a higher fraction of incorporation in phosphatidylglycerol. Triton X-100 inhibited incorporation of glycerol 3-phosphate into lipid, especially into phosphatidylglycerol.     

Testing four proposed barcoding markers for the identification of species within Ligustrum L. (Oleaceae)

DNA barcoding is a biological technique that uses short and standardized genes or DNA regions to facilitate species identification. DNA barcoding has been used successfully in several animal and plant groups. Ligustrum (Oleaceae) species occur widely throughout the world and are used as medicinal plants in China. Therefore, the accurate identification of species in this genus is necessary. Four potential DNA barcodes, namely the nuclear ribosomal internal transcribed spacer (ITS) and three chloroplast (cp) DNA regions (rbcL, matK, and trnH–psbA), were used to differentiate species within Ligustrum. BLAST, character-based method, tree-based methods and TAXONDNA analysis were used to investigate the molecular identification capabilities of the chosen markers for discriminating 92 samples representing 20 species of this genus. The results showed that the ITS sequences have the most variable information, followed by trnH–psbA, matK, and rbcL. All sequences of the four regions correctly identified the species at the genus level using BLAST alignment. At the species level, the discriminating power of rbcL, matK, trnH–psbA, and ITS based on neighbor-joining (NJ) trees was 36.8%, 38.9%, 77.8%, and 80%, respectively. Using character-based and maximum parsimony (MP) tree methods together, the discriminating ability of trnH–psbA increased to 88.9%. All species could be differentiated using ITS when combining the NJ tree method with character-based or MP tree methods. Overall, the results indicate that DNA barcoding is an effective molecular identification method for Ligustrum species. We propose the nuclear ribosomal ITS as a plant barcode for plant identification and trnH–psbA as a candidate barcode sequence.     

Optimization of Chlorpyrifos Degradation by Assembled Bacterial Consortium Using Response Surface Methodology

Chlorpyrifos is a commonly used organophosphate pesticide. Its extensive use and associated serious soil and water contamination have gained increasing environmental concern. Biodegradation is a promising way to remediate chlorpyrifos contamination. There are many reports on various chlorpyrifos degrading microorganisms, but only a few on biodegradation of chlorpyrifos by consortia. Hence, the present study attempted to assemble a novel bacterial consortium C5 for the biodegradation of chlorpyrifos. The 16S rRNA gene-based molecular analysis revealed that the bacterial consortium consisted of Staphylococcus warneri CPI 2, Pseudomonas putida CPI 9 and Stenotrophomonas maltophilia CPI 15. Optimization of chlorpyrifos degradation by the consortium C5, using a Box–Behnken design, was carried out taking into account four important variables: temperature, pH, the initial concentration of chlorpyrifos and time of incubation. C5 is capable of giving 90% degradation of chlorpyrifos (125 ppm) in 8 days of incubation under optimized conditions of pH (7) and temperature (30°C). Growth curve and degradation study under optimized conditions confirmed that consortium could improve the biodegradation potential. From these results, we conclude that the novel consortium C5 of three species can be used to eliminate chlorpyrifos from various environmental compartments and can be implemented in bioreactors in a cost-effective, safe and environmentally friendly manner.     

Recent advances in biocatalyst discovery,development and applications

Enzymes catalyze a wide range of biotransformations and have a great potential as environmentally friendly alternatives to classical chemical catalysts in various industrial applications. Recently, advanced techniques and strategies in enzyme discovery and engineering have led to the significant expansion of the quantity and functional diversity of biocatalysts, which has further allowed broader uses of biocatalysts in new processes, especially those traditionally enabled only by chemical catalysts. Here we highlight some of these recent advances with the focus on new approaches in biocatalyst discovery and development, and discuss new applications of selected biocatalysts including transaminases, cytochrome P450s, and Baeyer–Villiger monooxygenases.