DNA binding studies of antibiotic drug cephalexin using spectroscopic and molecular docking techniques

The purpose of this study was to explore an accurate characterization of the binding interaction of antibiotic drug cephalexin with calf thymus DNA (CT-DNA) as a relevant biological target by using UV absorption, fluorescence spectroscopy and circular dichroism (CD) in vitro under simulated physiological conditions (pH = 7.4) and also through a molecular modeling study. The results showed that the drug interacts with the DNA helix via a minor groove binding mode. The thermodynamic parameters were calculated and showed that the reaction between the drug and CT-DNA was exothermic. In addition, the drug enforced traceable changes in the viscosity of DNA. The molecular modeling results indicated that cephalexin forcefully binds to the minor groove of DNA with a relative binding energy of ?21.02?kJ mol^?1. The obtained theoretical results were in good agreement with those obtained from experimental studies.     

Targeting human telomeric DNA quadruplex with novel berberrubine derivatives: insights from spectroscopic and docking studies

Study on bioactive molecules, capable of stabilizing G-Quadruplex structures is considered to be a potential strategy for anticancer drug development. Berberrubine (BER) and two of its analogs bearing alkyl phenyl and biphenyl substitutions at 13-position were studied for targeting human telomeric G-quadruplex DNA sequence. The structures of berberrubine and analogs were optimized by density functional theory (DFT) calculations. Time-dependent DFT (B3LYP) calculations were used to establish and understand the nature of the electronic transitions observed in UV–vis spectra of the alkaloid. The interaction of berberrubine and its analogs with human telomeric G-quadruplex DNA sequence 5′-(GGGTTAGGGTTAGGGTTAGGG)-3′ was investigated by biophysical techniques and molecular docking study. Both the analogs were found to exhibit higher binding affinity than natural precursor berberrrubine. 13-phenylpropyl analog (BER1) showed highest affinity [(1.45 ± 0.03) × 10⁵ M^?1], while the affinity of the 13-diphenyl analog (BER2) was lower at (1.03 ± 0.05) × 10⁵ M^?1, and that of BER was (0.98 ± 0.03) × 10⁵ M^?1. Comparative fluorescence quenching studies gave evidence for a stronger stacking interaction of the analog compared to berberrubine. The thiazole orange displacement assay has clearly established that the analogs were more effective in displacing the end stacked dye in comparison to berberrubine. Molecular docking study showed that each alkaloid ligand binds primarily at the G rich regions of hTelo G4 DNA which makes them G specific binder towards hTelo G4 DNA. Isothermal titration calorimetry studies of quadruplex–berberrubine analog interaction revealed an exothermic binding that was favored by both enthalpy and entropy changes in BER in contrast to the analogs where the binding was majorly enthalpy dominated. A 1:1 binding stoichiometry was revealed in all the systems. This study establishes the potentiality of berberrubine analogs as a promising natural product based compounds as G-quadruplex-specific ligands.     

Landscape structural analysis of the Lençóis Maranhenses national park: implications for conservation

Our work evaluated the anthropic effects on the landscape structure of the Lençóis Maranhenses National Park (LMNP) and its Buffer Zone, and proposed strategies for the region’s conservation. LMNP is an important protected area in Brazilian north coast which protects a unique wetland ecosystem composed of sand dunes fields and a coastal vegetation called restinga. Supervised mapping of LMNP and a surrounding buffer of 3 km was carried out through high resolution and fine scale (1:5000) satellite images. The mapped area was subdivided in 1000 ha hexagonal Analysis Units (AU) and the following landscape metrics were calculated for each one of them: cover area (CA) of each soil cover class - dune fields (CA-DUNES), water bodies (CA-WATER), dense restinga (CADENSE), scattered restinga (CA-SCATTER), grassland (CA-SANDY), mangroves (CA-MANG), anthropogenic activity (CA-ANTRO) and, secondary vegetation (CA-SECOND); Landscape Shannon Diversity Index (SHDI), and; percentage of native vegetation cover (NV−COV). Pearson correlations were performed between the CA of each class and SHDI to identify the classes most correlated to CA-ANTRO. Our results showed that anthropic classes (crops, trails, and villages) had a stronger correlation (Pearson Correlation, r ≈ 0.65) with phytophysiognomies of dense restinga, secondary vegetation and SHDI, thus indicating that the land use conversion occurs in dense restinga areas and promotes vegetation secondarization, as well as increasing fragmentation. At least, 42% of the dense restinga habitats was destroyed due to human activities. Five conservation and restoration strategies were proposed in a local scale depending on the percentage of native vegetation cover on each AU, from the most to less conserved: (a) only conservation; (b) conservation with management; (c) management; (d) management and restoration; and, (e) restoration. The implementation of Agroforestry Systems with agro-successional restoration goals was recommended as an alternative for land use.     

Genetic resources of Tunisian Artemisia arborescens L. (Asteraceae), pattern of volatile metabolites concentration and bioactivity and implication for conservation

Artemisia arborescens L. (Asteraceae) is an endemic and a valuable medicinal and ornamental species in the Mediterranean regions. Despite the interest given to A. arborescens L. as promising medicinal crop, this species is becoming threatened of extinction in Tunisia as a result of the fragmentation of its habitat and the absence of any specific measures for its conservation and valorisation. Based on the last considerations, extent information about their volatile metabolites profiling, contents and antimicrobial potential were undertaken based on fourteen populations originated from various geographical and bioclimatic habitats of Tunisia. The obtained results reveal an essential oil content mean value of 1.47%. The leaves of Tunisian tree wormwood populations were dominated by camphor (15.05–58.05%), chamazulene (11.72–45.26%) and β-thujone (0–36.53%). Based on the three first major compounds detected for each population, four different oil types were defined (Oil type I: camphor-chamazulene-β-thujone; Oil type II: camphor-chamazulene-terpinen-4-ol; Oil type III: camphor-chamazulene-bornyl acetate; Oil type IV: camphor-chamazulene-linalool). PCA, HCA and Heatmap chemometric analyses revealed three classification clusters defined mainly by minor compounds. These minor volatile metabolites succeed to discriminate among the fourteen studied populations which promote their chemotaxonomic interest. Our findings confirm previous reports concerning this species in the world and show chamazulene, camphor and β-thujone as the major compounds of this species which define their well known chemotypes independently of the geographical, bioclimatic and genotypic factors. This makes of these three components promising chemosystematic tool for the discrimination of A. arborescens L. in the genus Artemisia. The results showed that the four tested oils were effective against the nine tested microbial strains. The highest antimicrobial potential was revealed for the population AAr_MB characterized by camphor, chamazulene and β-thujone as the dominant components. The pattern of essential oils concentration offers wide range of possibilities for the initiation of breeding programs according to the desired bioactive compounds. Both in situ and ex situ conservation strategies were suggested for the maintenance of the highest chemical polymorphism of this valuable medicinal species.     

Exploring the protein–protein interaction landscape in plants

Protein–protein interactions (PPIs) represent an essential aspect of plant systems biology. Identification of key protein players and their interaction networks provide crucial insights into the regulation of plant developmental processes and into interactions of plants with their environment. Despite the great advance in the methods for the discovery and validation of PPIs, still several challenges remain. First, the PPI networks are usually highly dynamic, and the in vivo interactions are often transient and difficult to detect. Therefore, the properties of the PPIs under study need to be considered to select the most suitable technique, because each has its own advantages and limitations. Second, besides knowledge on the interacting partners of a protein of interest, characteristics of the interaction, such as the spatial or temporal dynamics, are highly important. Hence, multiple approaches have to be combined to obtain a comprehensive view on the PPI network present in a cell. Here, we present the progress in commonly used methods to detect and validate PPIs in plants with a special emphasis on the PPI features assessed in each approach and how they were or can be used for the study of plant interactions with their environment.     

Laser chasing behaviour of wild fishes exploited as a tool to compare space use between size,sex and species

The spatial extent of animal movement is a key consideration when designing conservation measures, such as marine protected areas. Methods to assess territory size in the marine environment, however, are labour intensive and/or expensive. Here, we explore a novel method to investigate the spatial ecology of territorial fishes by examining their reactions to an artificial light stimulus. During benthic towed video surveys conducted in Lyme Bay, southwest England, several species of wrasse (Labridae) have frequently been observed pursuing a laser projected onto the seabed. While the motivation behind ‘laser‐chasing’ is unclear, we quantified the spatial aspects of this behaviour by comparing chase distance and chase likelihood between and within species, to determine the potential utility of this method for investigating space use and aggression in wild fishes. Cuckoo wrasse (Labrus mixtus) were significantly more likely to display agonistic behaviour towards the laser than Goldsinny wrasse (Ctenolabrus rupestris). Goldsinny wrasse displayed a positive relationship between total length and chase‐distance, but not Cuckoo wrasse. The observed species differences may relate to behavioural factors affecting the motivation behind ‘laser‐chasing’, which is discussed. Chases by the cuckoo wrasse were significantly longer than those by Goldsinny wrasse, and these chase distances were used to estimate theoretical territory sizes for each species. To our knowledge, this is the first study to explore the spatial aspects of the reactions to an artificial stimulus by wild fishes. The potential to develop the method to directly investigate aspects of territoriality and aggression in wild fishes is discussed, including necessary further refinements and testing. Wild wrasses are increasingly exploited in Europe to provide cleaner fish for salmonid aquaculture, and we encourage the development of methods to inform spatial conservation measures for these ubiquitous and iconic species.     

不同含水量大葱种子贮藏后的脂肪代谢研究

将大葱种子干燥成1．8％-10．5％的不同含水量后。在50℃、35℃、20℃和-18℃条件下密闭贮存16个月。通过对棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸含量的研究,结果表明,随着贮存温度的升高,种子中棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸含量不断升高,但在20℃和-18℃的差异不明显。在50℃下含水量为1．8％～6．6％的种子。5种脂肪酸含量明显大于含水量为7．4％-10.5％的种子。     

基于醇溶蛋白的20份小麦种质遗传完整性分析

采用醇溶蛋白电泳技术对同一品种不同繁殖年份的20份小麦种质进行遗传完整性分析。结果表明：供试种质中有10份具有一种醇溶蛋白谱带带型的同质性种质;另外10份具有2～4种醇溶蛋白谱带带型的异质性种质,其中6份为地方品种。表明地方品种具有较高的遗传多样性。在10份异质性种质中,两个繁殖年份种质之间的醇溶蛋白带型频率变化差异不显著的有5份,其第一繁殖年份的种质发芽率均高于75％,而另外5份存在显著差异的种质,第一年份的发芽率都低于66％。进一步分析表明,这10份异质性种质在两个繁殖年份之间,其发芽率差值与带型频率差值之间呈极显著正相关,相关系数为0．8665。上速结果表明,小麦更新时较高的发芽率是维持异质性种质遗传完整性的关键因素。     

Genetic diversity within and among populations of Shorea leprosula Miq. and Shorea parvifolia Dyer (Dipterocarpaceae) in Indonesia detected by AFLPs

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPL_p) of 53.32% and an expected heterozygosity (H _ep) of 0.16 in comparison with S. parvifolia showing PPL_p of 51.79% and H _ep of 0.14. At the species level, S. leprosula showed PPL_s of 92.86% and H _es of 0.21, while S. parvifolia showed PPL_s of 85.71% and H _es of 0.21. Genetic differentiation (G _st) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions.