Functional ecology of growth in seedlings versus root sprouts of Fagus grandifolia Ehrh.

We assessed growth differences and the foliar traits underpinning production in paired samples of juvenile American beech (Fagus grandifolia Ehrh.) that originated from seed versus root sprouts. Root sprouts had significantly greater relative extension growth rate and slightly greater leaf mass per unit area compared to seed-derived individuals, but neither light-saturated net photosynthetic rate nor foliar chlorophyll and nitrogen concentrations differed significantly between paired seedlings and sprouts. The greater height growth rate of saplings originating as root sprouts does not result from differing foliar function, but rather depends on translocation of assimilates from the parent tree to sustain this unusual and ecologically important dual regeneration strategy in American beech.     

Synthesis and antiprotozoal activity of 2,5-bis[amidinoaryl]thiazoles

Seven novel diamidino 2,5-bis(aryl)thiazoles (5a–g) were synthesized and evaluated against Trypanosoma brucei rhodensiense (T. b. r.) and Plasmodium falciparum (P. f.). The diamidines were obtained directly from the corresponding bis-nitriles (4a–g) by the action of lithium bis(trimethylsilyl)amide. The bis-nitriles 4a–f were synthesized in four steps starting with the Stille coupling of 2-tributyltinthiazole with the appropriate cyanoaryl halide. The bis-nitrile 5g was obtained by the palladium facilitated coupling of the mixed tin-silyl reagent 2-trimethylsilyl-5-trimethyltinthiazole with 2-bromo-5-cyanopyridine. The amidoxime potential prodrugs 6a–e, 6g were obtained by the reaction of hydroxylamine with the bis-nitriles. O-Methylation of the amidoximes gave the corresponding N-methoxyamidines 7a–c, 7e, 7g. The diamidines showed strong DNA binding affinity as reflected by ΔT_m measurements. Four of the diamidines 5a, 5b, 5d and 5e were highly active in vitro against P. f. giving IC₅₀ values between 1.1 and 2.5 nM. The same four diamidines showed IC₅₀ values between 4 and 6 nM against T. b. r. The selectivity indices ranged from 233 to 9175. One diamidine 5a produced one of four cures at an ip dose of 4 × 5 mg/kg in the STIB900 mouse model for acute African trypanosomiasis. The amidoxime and N-methoxyamidine of 5a were the only produgs to provide cures (1/4 cures) in the same mouse model on oral dosage at 4 × 25 mg/kg.     

HCV infection among Saudi population: high prevalence of genotype 4 and increased viral clearance rate

HCV is a major etiological agent of liver disease with a high rate of chronic evolution. The virus possesses 6 genotypes with many subtypes. The rate of spontaneous clearance among HCV infected individuals denotes a genetic determinant factor. The current study was designed in order to estimate the rate of HCV infection and ratio of virus clearance among a group of infected patients in Saudi Arabia from 2008 to 2011. It was additionally designed to determine the genotypes of the HCV in persistently infected patients. HCV seroprevalence was conducted on a total of 15,323 individuals. Seropositive individuals were tested by Cobas AmpliPrep/Cobas TaqMan HCV assay to determine the ratio of persistently infected patients to those who showed spontaneous viral clearance. HCV genotyping on random samples from persistently infected patients were conducted based on the differences in the 5'untranslated region (5'UTR). Anti-HCV antibodies were detected in 7.3% of the totally examined sera. A high percentage of the HCV infected individuals experienced virus clearance (48.4%). HCV genotyping revealed the presence of genotypes 1 and 4, the latter represented 97.6% of the tested strains. Evidences of the widespread of the HCV genotype 4 and a high rate of HCV virus clearance were found in Saudi Arabia.     

Ethanol production by Kluyveromyces lactis immobilized cells in copolymer carriers produced by radiation polymerization

The conditions for batch and continuous production of ethanol, using immobilized growing yeast cells of Kluyveromyces lactis, have been optimized. Yeast cells have been immobilized in hydrogel copolymer carriers composed of polyvinyl alcohol (PVA) with various hydrophilic monomers, using radiation copolymerization technique. Yeast cells were immobilized through adhesion and multiplication of yeast cells themselves. The ethanol production of immobilized growing yeast cells with these hydrogel carriers was related to the monomer composition of the copolymers and the optimum monomer composition was hydroxyethyl methacrylate (HEMA). In this case by using batch fermentation, the superior ethanol production was 32.9 g L(-1) which was about 4 times higher than that of cells in free system. The relation between the activity of immobilized yeast cells and the water content of the copolymer carriers was also discussed. Immobilized growing yeast cells in PVA: HEMA (7%: 10%, w/w) hydrogel copolymer carrier, were used in a packed-bed column reactor for the continuous production of ethanol from lactose at different levels of concentrations (50, 100 and 150) g L(-1). For all lactose feed concentrations, an increase in dilution rates from 0.1 h(-1) to 0.3 h(-1) lowered ethanol concentration in fermented broth, but the volumetric ethanol productivity and volumetric lactose uptake rate were improved. The fermentation efficiency was lowered with the increase in dilution rate and also at higher lactose concentration in feed medium and a maximum of 70.2% was obtained at the lowest lactose concentration 50 g L(-1).     

Exploration of larger central ring linkers in furamidine analogues: synthesis and evaluation of their DNA binding, antiparasitic and fluorescence properties

The effects of replacing the central furan ring of furamidine with indole and benzimidazole on their DNA binding affinity, antiparasitic activity and fluorescence are reported. The bis-cyanophenylindoles required to make the corresponding amidines were prepared by sequential Stille and/or Suzuki coupling reactions. The bis-cyanophenylbenzimidazoles were obtained by coupling 4-cyanobenzaldehydes with the appropriate cyano substituted phenylenediamine. The bis-nitriles were converted to the diamidines by reaction with LiN[Si(CH(3))(3)](2) or by Pinner methodology. Specifically, we have prepared new series of 2,6- and 2,5-diaryl indoles (6a,b, 12 and 17a-d) and the related benzimidazoles (24, 30 and 35). The new compounds bind in the DNA minor groove in DNA AT base pair sequences and eight of the ten new analogues exhibit ΔT(m) values comparable to or higher than that of furamidine. Six of ten of the new compounds exhibit lower IC(50) values against Trypanosoma brucei rhodesiense (T. b. r.) and eight of ten exhibit lower IC(50) values against Plasmodium falciparum (P. f.) than furamidine. Four of the ten show greater efficacy than furamidine in the rigorous T. b. r. STIB900 mouse model for African trypanosomiasis. Generally, the fluorescence properties of the new analogues are similar to that of DAPI.     

Bioaccumulation and translocation of nine heavy metals by Eichhornia crassipes in Nile Delta,Egypt: perspectives for phytoremediation

Abstract

The current research was carried out to estimate the potential of water hyacinth (WH) for removal of nine heavy metals (HMs) from three irrigation canals in Nile Delta. Sampling was achieved in monospecific and homogeneous WH stands at three irrigation canals in the study area, and WH biomass was sampled at monthly intervals from April 2014 to November 2014 using five randomly distributed quadrats (each 0.5?×?0.5?m) at each canal. All HM concentrations were significantly higher in the roots compared with the other WH organs. The WH was recognized by a bioaccumulation factor >1.0 for all HMs. The WH was recognized by translocation factor <1.0 for all HMs (except Pb). In many cases, the concentrations of the HMs in the different organs of WH were correlated with the same HMs in the water. Such correlations indicate that WH reflects the cumulative influences of environmental pollution from the water, and thereby suggesting its potential use in the bio-monitoring of most examined HMs. In conclusion, WH is a promising macrophyte for remediation of irrigation canals polluted with Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn.     

Ecological impacts of desert plantation forests on biodiversity

This investigation involves the comparison of the diversity of understorey vegetation of four desert planted forests with the adjacent desert areas. Spatial and temporal variations in species composition and structure were compared, and alpha and beta diversities were compared for the field data collected from sampled sites. The diversity of native desert species decreased from 66% in desert areas to 44% of the total recorded plants inside the forests. Meanwhile, the percentage of agricultural weed species increased in forests to >twofold more than that recorded in desert areas. Plant communities in forest stands shared <50% of their species with adjacent vegetation in desert stands. The percentage of variation in species composition was >340% in some forests compared with the desert areas. Alpha diversity and β‐diversity were significantly higher in forest stands than in the desert. Spatial and temporal variations in species diversity were correlated with type of tree canopy and irrigation system. Planted forests had significant negative effects on the diversity of native desert shrubs and trees. Using flood irrigation and more spacing between trees might help in conserving the floristic diversity of desert shrubs and trees at the forest floor.