A conductometric enzymatic methanol sensor based on polystyrene - PAMAM dendritic polymer electrospun nanofibers.

Methanol (MeOH) is a solvent and cleaning agent used in industry, but it is poisonous when ingested. The recommended release threshold for MeOH vapor is 200 ppm. We present a novel sensitive micro-conductometric MeOH biosensor created by grafting alcohol oxidase (AOX) onto electrospun polystyrene-poly(amidoamine) dendritic polymer blend nanofibers (PS-PAMAM-ESNFs) on interdigitated electrodes (IDEs). The analytical performance of the MeOH microsensor was evaluated using gaseous MeOH, ethanol, and acetone samples collected from the headspace above aqueous solution with known concentration. The sensor's response time (tRes) fluctuates from 13 s to 35 s from lower to higher concentrations. The conductometric sensor has a sensitivity of 150.53 µS.cm-1 (v/v) for MeOH and a detection limit of 100 ppm in the gas phase. The MeOH sensor is 7.3 times less sensitive to ethanol and 136.8 times less sensitive to acetone. The sensor was verified for detecting MeOH in commercial rubbing alcohol samples.

Induction of PR-10 genes and metabolites in strawberry plants in response to Verticillium dahliae infection.

BACKGROUND: The soil-borne vascular pathogen Verticillium dahliae causes severe wilt symptoms in a wide range of plants including strawberry (Fragaria × ananassa). To enhance our understanding of the effects of V. dahliae on the growth and development of F. × ananassa, the expression patterns of 21 PR-10 genes were investigated by qPCR analysis and metabolite changes were determined by LC-MS in in vitro F. × ananassa plants upon pathogen infection. RESULTS: The expression patterns of the 21 isoforms showed a wide range of responses. Four PR-10 genes were highly induced in leaves upon pathogen infection while eight members were significantly up-regulated in roots. A simultaneously induced expression in leaves and roots was detected for five PR-10 genes. Interestingly, two isoforms were expressed upon infection in all three tissues (leaves, roots and stems) while no induction was detected for two other members. Accumulation of antifungal catechin and epicatechin was detected upon pathogen infection in roots and stems at late stages, while caffeic acid and citric acid were observed only in infected roots. Production of abscisic acid, salicylic acid, jasmonic acid (JA), gibberellic acid and indole acetic acid (IAA) was induced in infected leaves and stems at early stages. IAA and JA were the sole hormones to be ascertained in infected roots at late stages. CONCLUSIONS: The induction of several PR-10 genes upon infection of strawberry plants with V. dahliae suggest a role of PR-10 genes in the defense response against this pathogen. Production of phytohormones in the early stages of infection and antifungal metabolites in late stages suppose that they are implicated in this response. The results may possibly improve the control measures of the pathogen.

Phosphorylation-dependent ribonuclease activity of Fra a 1 proteins.

Abiotic and biotic stress situations cause the upregulation of the transcription of a number of plant defence genes. They code for so-called pathogenesis-related (PR) proteins such as PR proteins of class-10 (PR-10), whose biological functions are still unclear. PR10 proteins are members of the Bet v 1 (major birch pollen allergen) superfamily including related proteins from the cultivated strawberry Fragaria × ananassa (Fra a 1 proteins). Here, we analyzed the expression of 21 Fra a 1 genes in different tissues of the strawberry plant by quantitative real-time PCR. Thirteen members were mainly expressed in roots, three in stems, two in red fruits and leaves, and one in flowers. Five genes (Fra a 1.04-1.08) were selected based on their expression profiles, heterologously expressed in Escherichia coli, and their recombinant proteins functionally characterized. Ribonuclease activity, demonstrated by in-solution and in-gel RNA degradation assays, indicated complete hydrolysis of RNA only by Fra a 1.06. Moreover, phosphorylation assays showed that except for Fra a 1.06, the remaining four recombinant proteins were phosphorylated. Consequently, we investigated whether the phosphorylation status of the proteins affects their ribonuclease activity. Using an in-solution as well as an in-gel RNase activity assay, results demonstrated that the four recombinant proteins, dephosphorylated with phosphatases, exhibited ribonucleolytic activity against total RNA. Thus, the PR10 related proteins characterized in this study harbour a phosphorylation-dependent RNase activity. The results shed new light on the assumed function of PR10 proteins in plant defence.

Fra a 1.02 Is the Most Potent Isoform of the Bet v 1-like Allergen in Strawberry Fruit.

The strawberry fruit proteins Fra a 1.01E-1.08 are homologues of the major birch pollen allergen Bet v 1. Three of the proteins are known to have essential biological functions in pigment formation during fruit ripening and seem to be responsible for allergic reactions to strawberry fruit. We evaluated the cross-reactive allergenic potential of these putative strawberry allergens in patients allergic to birch pollen. Activation of basophils of eight atopic patients was studied using different concentrations of Fra a 1 isoforms. Bet v 1a was used as control and as atopic patient selection criterion. Although Fra a 1.01E-1.08 have amino acid sequence identities of 74.5-97.5% with Fra a 1.02, the basophil activation mediated by the eight Fra a 1 proteins differed substantially. Fra a 1.03 and Fra a 1.02 showed the highest activation of basophils, 73 and 66% of total basophils, respectively. On the basis of the high relative expression of the gene Fra a 1.02 in ripe strawberry fruits of allergenic varieties, Fra a 1.02 was identified as the main strawberry allergen of the Bet v 1 superfamily. Knowledge of the allergenic potential of Fra a 1.02/1.03 will help to improve food safety and can serve as a valuable marker for the development of red-fruited hypoallergenic strawberry cultivars.

Chlamydia trachomatis genovar distribution in clinical urogenital specimens from Tunisian patients: high prevalence of C. trachomatis genovar E and mixed infections.

BACKGROUND: This epidemiological study was carried out in Sfax (south of Tunisia) and focused on genital Chlamydia trachomatis (C. trachomatis) genovar distribution. METHODS: One hundred and thirty seven genital samples from 4067 patients (4.2%) attending the Habib Bourguiba University hospital of Sfax over 12 years (from 2000 to 2011) were found to be C. trachomatis PCR positive by the Cobas Amplicor system. These samples were genotyped by an in house reverse hybridization method. RESULTS: One hundred and eight (78.8%) samples contained only one genovar and 29 (21.2%) samples contained two or three genovars. Genovar E was the most prevalent (70.8%) single genovar and it was detected in 90.6% of all the cases. Genovars J, C and L1-L3 were not detected in our samples whereas ocular genovars A and B were in 5 cases. All the five cases were mixed infections. Men had more mixed infections than women (p=0.02) and were more frequently infected by genovars F and K (p<0.05). No associations between current infection, infertility and the genovar distribution were observed. Patients coinfected with Neisseria gonorrhoeae were also significantly more frequently infected with mixed genovars (p=0.04). CONCLUSIONS: In conclusion, we have reported a high prevalence of genovar E and of mixed infections in our study population. Such data could have implications for the control and vaccine development of C. trachomatis in Tunisia.