Linum mucronatum: organ to organ lignan variations

The percentage of podophyllotoxin (PTOX) and its congener lignans were measured by HPLC in Linum mucronatum ssp. mucronatum (Linaceae) fresh plant organs. The highest amounts of PTOX (0.595 +/- 0.060% g/g dry wt) and 6-methoxypodophyllotoxin (MPTOX) (1.491 +/- 0.125% g/g dry wt) were found in the plant sexual organs. Whereas, the highest levels of beta-peltatin, 5'-demethoxy-MPTOX and yatein were found in not developed buds, petals and sepals, respectively.     

Molecular detection and isolation from antarctica of methylotrophic bacteria able to grow with methylated sulfur compounds

This study is the first demonstration that a diverse facultatively methylotrophic microbiota exists in some Antarctic locations. PCR amplification of genes diagnostic for methylotrophs was carried out with bacterial DNA isolated from 14 soil and sediment samples from ten locations on Signy Island, South Orkney Islands, Antarctica. Genes encoding the mxaF of methanol dehydrogenase, the fdxA for Afipia ferredoxin, the msmA of methanesulfonate monooxygenase, and the 16S rRNA gene of Methylobacterium were detected in all samples tested. The mxaF gene sequences corresponded to those of Hyphomicrobium, Methylobacterium, and Methylomonas. Over 30 pure cultures of methylotrophs were isolated on methanesulfonate, dimethylsulfone, or dimethylsulfide from ten Signy Island lakes. Some were identified from 16S rRNA gene sequences (and morphology) as Hyphomicrobium species, strains of Afipia felis, and a methylotrophic Flavobacterium strain. Antarctic environments thus contain diverse methylotrophic bacteria, growing on various C1-substrates, including C1-sulfur compounds.     

Effect of Mixed Cultures on Antibiotic Susceptibility Testing

Careful studies of the antibiotic susceptibilities of mixtures of bacteria likely to be encountered in clinical cultures have shown that the results obtained are completely unreliable. Mixtures of resistant and sensitive species appeared either as "resistant" or "sensitive" depending upon the organisms and the drug. A number of sensitive species gave reactions interpreted as resistant when tested in combination. Since reactions of bacterial mixtures are completely unpredictable, the authors emphasize that antibiotic susceptibility testing be limited to pure cultures.     

Morphological and physiological response of tomato (Solanum lycopersicum L.) to natural and synthetic cytokinin sources: a comparative study

Among the natural plant growth stimulants, moringa has attained enormous attention due to its leaf composition being enriched with cytokinin, antioxidants and minerals. Exogenous application of moringa leaf extract (MLE) improves productivity in many crops. This study investigated the potential of MLE with different dilutions, i.e., MLE0, MLE10, MLE20 and MLE30 (0, 10, 20 and 30 times diluted in water, respectively) to improve the performance of tomato. Foliage-applied water and benzylaminopurine (BAP, 50 mg L^?1) were taken as controls. Among treatments, foliar-applied MLE30 produced maximum vegetative and flowering branches, number of flowers and heaviest fruits per plant of tomato in comparison with synthetic BAP and other treatments. A similar increase in vegetative and flowering branches was recorded for root-applied MLE20 including BAP. Foliage-applied MLE30 also increased chlorophyll (a) pigments and leaf total soluble proteins than other stimulants used. This increase was followed by enhanced antioxidant activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), total phenolics in leaves and fruit lycopene contents of tomato. In general, foliar application of MLE30 was more effective as natural biostimulant to improve growth, productivity and fruit quality of tomato as compared to synthetic BAP and its root application.     

Aldrin Epoxidation in Flathead Mullet (Mugil cephalus): Possible Involvement of CYP1A and CYP3A

The primary objective of this study was to determine specific cytochrome P450 isozyme(s) involved in the metabolism of aldrin to its toxic metabolite dieldrin in flathead mullet (Mugil cephalus) liver microsomes. To identify the cytochrome P450 isozyme responsible for the aldrin metabolism in mullet liver, the effects of mammalian‐specific cytochrome P450 inhibitors and substrates were determined in the epoxidation reaction of aldrin. CYP3A‐related inhibitors, ketoconazole, SKF‐525A, and cimetidine, inhibited the metabolism of aldrin. The contribution of CYP1A to the aldrin metabolism was shown by the inhibition of 7‐ethoxyresorufin‐O‐deethylase activity in the presence of aldrin. The results indicate that CY1A and CYP3A are the cytochrome P450s involved in aldrin epoxidase activity in mullet. In addition, the suitability of aldrin epoxidase activity for monitoring of environmental pollution was also assessed in the fish samples caught from four different locations of the West Black Sea coast of Turkey.     

Comparative Genomics and Transduction Potential of Enterococcus faecalis Temperate Bacteriophages

To determine the relative importance of temperate bacteriophage in the horizontal gene transfer of fitness and virulence determinants of Enterococcus faecalis, a panel of 47 bacteremia isolates were treated with the inducing agents mitomycin C, norfloxacin, and UV radiation. Thirty-four phages were purified from culture supernatants and discriminated using pulsed-field gel electrophoresis (PFGE) and restriction mapping. From these analyses the genomes of eight representative phages were pyrosequenced, revealing four distinct groups of phages. Three groups of phages, ΦFL1 to 3, were found to be sequence related, with ΦFL1A to C and ΦFL2A and B sharing the greatest identity (87 to 88%), while ΦFL3A and B share 37 to 41% identity with ΦFL1 and 2. ΦFL4A shares 3 to 12% identity with the phages ΦFL1 to 3. The ΦFL3A and B phages possess a high DNA sequence identity with the morphogenesis and lysis modules of Lactococcus lactis subsp. cremoris prophages. Homologs of the Streptococcus mitis platelet binding phage tail proteins, PblA and PblB, are encoded on each sequenced E. faecalis phage. Few other phage genes encoding potential virulence functions were identified, and there was little evidence of carriage of lysogenic conversion genes distal to endolysin, as has been observed with genomes of many temperate phages from the opportunist pathogens Staphylococcus aureus and Streptococcus pyogenes. E. faecalis JH2-2 lysogens were generated using the eight phages, and these were examined for their relative fitness in Galleria mellonella. Several lysogens exhibited different effects upon survival of G. mellonella compared to their isogenic parent. The eight phages were tested for their ability to package host DNA, and three were shown to be very effective for generalized transduction of naive host cells of the laboratory strains OG1RF and JH2-2.Enterococcus faecalis is a member of the natural flora of humans and colonizes the gastrointestinal and vaginal tracts and the oral cavity. In recent years it has emerged as an important opportunistic nosocomial pathogen and is a causative agent of bacteremia, infective endocarditis, and surgical wound and urinary tract infections. The accumulation of acquired antibiotic resistance determinants, in addition to its intrinsic resistance and tenacity, has given rise to the evolution of clinical isolates of E. faecalis that are therapeutically problematic (19). Greater notoriety was afforded to this species following the observed transfer of the conjugative transposon Tn1546 to Staphylococcus aureus, imparting vancomycin resistance (11). Subsequent analysis has revealed that multiple independent E. faecalis-dependent vanA transfers had occurred in the United States prior to 2007 (50). This places enterococci in an important and dynamic position within the health care system, warranting their increased study.The specific determinants that are proposed to contribute to the virulence of E. faecalis are not universally present, and expression of the cognate genes is variable (21, 37). For example, in a recent study of 106 clonally diverse strains of E. faecalis the metallopeptidase gelatinase (GelE) was shown to be expressed in less than 60% of 106 genotypically positive isolates, whereas expression of cytolysin was less frequently observed (expression in ∼25% of isolates, with 30% being genotypically positive) (33). A proposed pathogenicity island identified with E. faecalis V583 (49) is composed of a variable gene set encoding the virulence determinants enterococcal surface protein, cytolysin, and aggregation substance. This highly variable 150-kb mobile element contains many components of unknown function that are hypothesized to facilitate survival and/or transmission in the health care setting (34, 40, 49).Two sequenced and annotated genomes of E. faecalis have been completed and published to date. These are the blood isolate and first-observed vancomycin-resistant strain V583 (40) and the oral isolate OG1RF, used as a common laboratory strain (8). A major difference between these genomes is the presence in V583 of seven regions containing phage-associated sequences. In contrast, OG1RF contains only one phage remnant, which was proposed by McBride et al. (33) to form part of the core genome, a theory supported by the presence in OG1RF of this phage remnant region together with two CRISPR loci. CRISPR sequences provide sequence-specific resistance to bacteriophages via the assembly of phage DNA sequences interspersed as spacers between repeats, in concert with associated cas genes, which collectively operate as an RNA-based gene silencing mechanism (5, 6, 28, 30, 36, 42). This elegant heritable mechanism is proposed to limit horizontal gene transfer of bacteriophage, transposable elements, and conjugative plasmids (9, 10, 32).Within the firmicute division of Gram-positive bacteria, temperate bacteriophages are key vectors for the horizontal transfer of virulence genes. In Staphylococcus aureus, bacteriophages encode and mobilize an impressive array of immune evasion genes (54, 55) and Panton-Valentine leukocidin (43). Several bacteriophage-encoded virulence determinants also contribute to pathogenesis in group A Streptococcus (2, 3, 4).The role of bacteriophages in the virulence of E. faecalis is not clear. Encoded within seven phage-related sequences of strain V583, there are multiple reported homologs of the Streptococcus mitis platelet-binding proteins PblA and PblB (7) and a ferrochelatase (40). In contrast, the absence of mobile genetic elements (MGEs) in strain OG1RF led Bourgogne et al. (8) to speculate that they did not engender virulence in E. faecalis.In this study we determined the morphology and complete genome sequences of eight induced bacteriophages purified from clinical isolates of E. faecalis. We sought to determine the potential carriage of genes that might contribute to the virulence or fitness of this organism and characterize the capacity of these phages to participate in transduction.     

Protective Efficacy of Intermittent Preventive Treatment of Malaria in Infants (IPTi) Using Sulfadoxine-Pyrimethamine and Parasite Resistance

Background

Intermittent Preventive Treatment of malaria in infants using sulfadoxine-pyrimethamine (SP-IPTi) is recommended by WHO for implementation in settings where resistance to SP is not high. Here we examine the relationship between the protective efficacy of SP-IPTi and measures of SP resistance.

Methods and Results

We analysed the relationship between protective efficacy reported in the 7 SP-IPTi trials and contemporaneous data from 6 in vivo efficacy studies using SP and 7 molecular studies reporting frequency of dhfr triple and dhps double mutations within 50km of the trial sites. We found a borderline significant association between frequency of the dhfr triple mutation and protective efficacy to 12 months of age of SP-IPTi. This association is significantly biased due to differences between studies, namely number of doses of SP given and follow up times. However, fitting a simple probabilistic model to determine the relationship between the frequency of the dhfr triple, dhps double and dhfr/dhps quintuple mutations associated with resistance to SP and protective efficacy, we found a significant inverse relationship between the dhfr triple mutation frequency alone and the dhfr/dhps quintuple mutations and efficacy at 35 days post the 9 month dose and up to 12 months of age respectively.

Conclusions

A significant relationship was found between the frequency of the dhfr triple mutation and SP-IPTi protective efficacy at 35 days post the 9 month dose. An association between the protective efficacy to 12 months of age and dhfr triple and dhfr/dhps quintuple mutations was found but should be viewed with caution due to bias. It was not possible to define a more definite relationship based on the data available from these trials.     

Studies on the superoxide anion production and peroxidase activity in potato leaf cell suspension exposed to salicylic acid

It is now widely accepted that salicylic acid (SA) signaling is mediated by reactive oxygen species (ROS) production. We have studied the effect of SA on peroxidase activity and superoxide anion production in potato leaf cell suspension. The results show that potato cells are insensitive to low concentrations of exogenous SA (< 1 mM) and the effect is observed at 1–5 mM SA. The cells exposed to SA exhibit higher peroxidase activity and show different peroxidase pattern when analyzed on native gels compared to the control. Superoxide anion production is enhanced after two hours of treatment and 2.5 mM SA gives the highest value. The results suggest peroxidase-mediated detoxification of ROS elicited by SA.