生态旅游区的景观生态问题及其调控

目前,在生态旅游开发过程中存在着许多生态破坏现象,严重影响生态旅游的可持续发展,是生态旅游区建设中亟待重视的问题。本文总结了当前我国生态旅游区在发展生态旅游过程中存在的生态破坏问题,并运用景观生态学、旅游生态学的原理和方法提出了解决生态旅游区生态问题的景观生态调控对策和措施,包括进行旅游景观生态规划、设计合理的旅游生态管理容量、对旅游景观结构进行生态化设计、构建景观生态安全格局、加强旅游生态教育和旅游环境监测等方面。     

昆虫抗菌肽基因工程及其分子设计研究进展(英文)

昆虫抗菌肽是昆虫免疫后存在于血淋巴中的一类活性肽,具有广谱抗菌的生物活性,因而昆虫抗菌肽基因工程迅速成为生命科学领域的研究热点之一.介绍了昆虫抗菌肽的基因结构和表达,综述了昆虫抗菌肽的人工合成与改造以及转基因工程的研究成果,概述了昆虫抗菌肽的分子设计方法和现状,并展望了昆虫抗菌肽的应用前景.     

Stenotrophomonas maltophilia Gd2: A potential and novel isolate for fibrinolytic enzyme production

The bacterium with an ability to produce extracellular fibrinolytic protease was isolated and identified as Stenotrophomonas maltophilia Gd2 based on ribotyping. The in-vitro fibrinolytic profile of this enzyme depicted 73% of fibrin clot dissolution within 4 h. Fibrinolytic enzyme yield influenced by different physiological (incubation time, temperature, agitation and pH), nutritional (macronutrients such as carbon and nitrogen sources) and biological (inoculums age and inoculums concentration) parameters of fermentation which were optimized based on one-factor-at-a-time (OFAT) approach. The enzyme yield improved from 886 to 1795 FU ml⁻¹ upon OFAT; optimized conditions include temperature – 33 °C, pH – 8.0, incubation time – 36 h, agitation – 150 RPM, 3% v/v inoculums and age of inoculum – 18 h. Further optimization of enzyme production was achieved with implementation of Plackett-Burman media designing where the production levels increased to 3411 FU ml⁻¹ and noticed that peptone, pH, dextrose and K₂HPO₄ was found to be significant factor. This ms reports the highest fibrinolytic enzyme yield with S. maltophilia to that of literature reports.     

图位克隆技术新型遗传学实验教学项目的设计与实践

染色体重组与连锁互换是遗传学教学的重点和难点。为使学生更好地理解此方面知识, 我们课题组前期利用图位克隆(map-based cloning)技术, 克隆了1个调控水稻(Oryza sativa)类病变表型的基因SPL5, 并基于此设计了一个新的综合型遗传学实验, 即利用DNA分子标记对基因进行定位。实验中学生利用水稻spl5突变体与野生型杂交获得的F₂代定位群体和多态性分子标记, 对spl5突变进行染色体连锁分析、初步定位和遗传作图。该教学实验不仅可有效促进学生对遗传学三大定律的理解, 而且对其开阔视野、提高解决问题和团队协作的能力也有促进作用。     

Gene Expression Analysis with No Sequence Data: Study on Reeves’s Muntjac (Muntiacus reevesi)

Despite scientific progress, the gene sequences for many species not commonly used in research have not yet been analyzed. This makes it difficult to carry out molecular studies on such animals, as the sequence of genes is the basic information used in many techniques. In this study, we attempt to design primers for a real-time PCR analysis, basing on a comparative analysis of selected gene sequences of species related to Reeves’s muntjac (Muntiacus reevesi) and by identifying highly conservative regions. Results of PCR products sequencing and their alignment with the GenBank collection show that all selected primers gave products highly similar (> 90%) to the intended target (among compared species), which led us to the conclusion that our primers may be used for further analyses of gene expression.     

Molecular epidemiology of antibiotic-resistant genes and potent inhibitors against TEM,CTX-M-14, CTX-M-15, and SHV-1 proteins of Escherichia coli in district Peshawar,Pakistan

The Extended Spectrum Beta-Lactamases (ESBLs) producing bacteria is an issue of concern for clinicians resulting in minimize the treatment options. To overcome resistance mechanisms, novel inhibitors with good Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties must inhibit the ESBLs resistant genes. The current study aimed to identify the antibiotic resistance genes of ESBLs producing E. coli and a single inhibitor was designed to inhibit all the resistant proteins. The results showed that 42.9% ESBL producers had CTX-M (69.9%), TEM (63.4%), SHV (34.5%) and CTX-M-14 (17.5%) genes. The ESBLs producing isolates were resistant to cephalosporins, quinolones, and sulfonamide with Minimum Inhibitory Concentration (MICs) ranging from 64 to >256 μg/ml. To design multi inhibitory ligands, RECAP synthesis was used for the de-novo discovery of 1000 inhibitors database. Protein crystal structures were retrieved from Protein Data Base (PDB). Lipinski’s rules of five were applied to the novel inhibitors database to improve the ADMET properties. The novel inhibitors database was selected for docking simulations. Placement of the ligand was used by the London dG algorithm implemented in Molecular Operating Environment (MOE), while GBVI/WSA dG algorithm was used for final refinement. Based on docking score, visual inspection of ligands interaction with key residues, binding affinity, and binding energy of ligands with proteins, ten compounds were selected for ESBLs proteins with best ADMET properties, binding energy, and binding affinity the reported ones. These hits compounds have unique scaffolds and are predicted to be a starting point for developing potent inhibitors against antibiotic-resistant proteins.     

Design,synthesis, in vitro Evaluation and docking studies on dihydropyrimidine-based urease inhibitors

In our previous report, we have identified 3,4-dihydropyrimidine scaffold as promising class of urease inhibitor in a structure based virtual screen (SBVS) experiment. In present study, we attempted to optimize the scaffold by varying C-5 substituent. The elongation of the C-5 chain was achieved by the reaction of C-5 ester with hydrazine leading to C-5 carbohydrazides which were further used as building blocks for the synthesis of fifteen new compounds having diverse moieties. A significantly higher in vitro urease inhibitory activity with IC₅₀ values in submicromolar range was observed for semithiocarbazide derivatives (4a-c, 0.58–0.79 µM) and isatin Schiff base derivative 5a (0.23 µM). Docking analysis suggests that the synthesized compounds were anchored well in the catalytic site and extending to the entrance of binding pocket and thus restrict the mobility of the flap by interacting with its key amino acid residues. The overall results of urease inhibition have shown that these compounds can be further optimized and developed as lead urease inhibitors.     

Modeling of human M1 aminopeptidases for in silico screening of potential Plasmodium falciparum alanine aminopeptidase (PfA-M1) specific inhibitors

Plasmodium falciparum alanine M1-aminopeptidase (PfA-M1) is a validated target for anti-malarial drug development. Presence of significant similarity between PfA-M1 and human M1-aminopeptidases, particularly within regions of enzyme active site leads to problem of non-specificity and off-target binding for known aminopeptidase inhibitors. Molecular docking based in silico screening approach for off-target binding has high potential but requires 3D-structure of all human M1-aminopeptidaes. Therefore, in the present study 3D structural models of seven human M1-aminopeptidases were developed. The robustness of docking parameters and quality of predicted human M1-aminopeptidases structural models was evaluated by stereochemical analysis and docking of their respective known inhibitors. The docking scores were in agreement with the inhibitory concentrations elucidated in enzyme assays of respective inhibitor enzyme combinations (r2≈0.70). Further docking analysis of fifteen potential PfA-M1 inhibitors (virtual screening identified) showed that three compounds had less docking affinity for human M1-aminopeptidases as compared to PfA-M1. These three identified potential lead compounds can be validated with enzyme assays and used as a scaffold for designing of new compounds with increased specificity towards PfA-M1.     

Developing Hispolon-based novel anticancer therapeutics against human (NF-κβ) using in silico approach of modelling,docking and protein dynamics

Abstract

Hispolon is a polyphenolic compound derived from black hoof mushroom (Phellinus linteus) or shaggy bracket mushroom (Inonotus hispidus) which induces the inhibition of cancer-promoting nuclear factor-kappa beta (NF-κβ) complex. To develop more potent lead molecules with enhanced anticancer efficiency, the mechanism of hispolon-mediated nuclear factor-κβ inhibition has been investigated by molecular modelling and docking. Ten derivatives of hispolon (DRG1-10) have been developed by pharmacophore-based design with a view to enhance the anticancer efficacy. Hispolon and its derivatives were further screened for different pharmacological parameters like binding free energy, drug likeliness, absorption–digestion–metabolism–excretion (ADME), permeability, mutagenicity, toxicity and inhibitory concentration 50 (IC50) to find a potent lead molecule. Based on pharmacological validation, comparative molecular dynamics (MD) simulations have been performed for three lead molecules: Hispolon, DRG2 and DRG7 complexed with human NF-κβ up to 50?ns. By analysing different factors like root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA) and principal component analysis (PCA), Gibb’s free energy plots DRG2 have more binding efficiency compared to hispolon and DRG7. In RMSD plot, hispolon-bound NF-κβ has the most deviation within a range between 0.125 and 0.45?nm, and DRG2-bound complex showed the range between 0.125 and 0.25?nm. The residues of NF-κβ responsible for hydrophobic interactions with ligand, e.g. Met469, Leu522 and Cys533, have the lowest fluctuation values in DRG2-bound complex. The average Rg fluctuation for DRG2-bound NF-κβ has been recorded under 2.025?nm for most of the simulation time which is much less compared to hispolon and DRG7. Gibb’s free energy plots also define the highest stability of DRG2-bound NF-κβ.

Communicated by Ramaswamy H. Sarma