Phototropism in Dunaliella and its application in a harvesting device.

Summary The influence of wavelength, light intensity and algal concentration on the phototropism of Dunaliella sp. is described. A practical device for harvesting the alga, based in this effect is shown.     

Littoral diatoms as indicators for the eutrophication of shallow lakes

The littoral zone of shallow water bodies in the Czech Republic has been studied quite consistently at several fishponds. The use of algae, especially diatoms, for the monitoring of the state of lotic freshwater also has a long tradition. The main objective of the presented paper is to validate the feasibility of the use of littoral periphyton comunities for the biomonitoring of standing waters. At the investigated sites, littoral periphytic diatoms were studied together with selected enviromental variables (pH, conductivity, nutrients – especially total phosphorus) on three types of natural substrates (epilithon, epiphyton, epipelon). The evaluation of the diatom community was performed on the basis of the checklists of algal indicator species published by authors from the Czech Republic, Austria and the Netherlands. The data were subjected to statistical software NCCS 2000 (GLM Anova and ``Ward's minimum'' variance cluster analysis). Littoral periphytic diatoms appear to be good indicators of the fishpond water quality. The selected substrates show non-significant differences therefore the average values from all substrates were used. The best indicatory system for evaluation of Czech fishponds was van Dam's index.

     

Crustaceans as biological indicators of heavy metal pollution in Lake Balaton (Hungary)

Hydrobiologia - Trace metals (Cd, Cu, Pb, Zn) were measured in mixed zooplankton samples collected from the open water of Lake Balaton (Hungary) in order to assess spatial and seasonal changes in...     

Zinc content of Escherichia coli-expressed constitutive isoforms of nitric-oxide synthase. Enzymatic activity and effect of pterin.

Recently, we obtained x-ray crystallographic data showing the presence of a ZnS4 center in the structure of Escherichia coli-expressed bovine endothelial nitric-oxide synthase (eNOS) and rat neuronal nitric-oxide synthase (nNOS). The zinc atom is coordinated by two CXXXXC motifs, one motif being contributed by each NOS monomer (cysteine 326 through cysteine 331 in rat nNOS). Mutation of the nNOS cysteine 331 to alanine (C331A) results in the loss of NO. synthetic activity and also results in an inability to bind zinc efficiently. Although prolonged incubation of the C331A mutant of nNOS with high concentrations of L-arginine results in a catalytically active enzyme, zinc binding is not restored. In this study, we investigate the zinc stoichiometry in wild-type nNOS and eNOS, as well as in the C331A-mutated nNOS, using a chelation assay and electrothermal vaporization-inductively coupled plasma-mass spectrometry. The data reveal an approximate 2:1 stoichiometry of heme to zinc in (6R)-5,6,7,8-tetrahydro-L-biopterin-replete, wild-type nNOS and eNOS and show that the reactivated C331A mutant of nNOS has a limited ability to bind zinc. The present study substantiates that the zinc in NOS is structural rather than catalytic and is important for maintaining optimally functional, enzymatically active, constitutive NOSs.     

Overall assessment of Monodus subterraneus cultivation and EPA production in outdoor helical and bubble column reactors

The outdoor production of Monodus subterraneus wasstudied in bubble column and helical reactors, mainly analysing the influenceofdilution rate, air flow rate and solar irradiance on growth rate andbiochemicalcomposition. Photoinhibition and photo-oxidation phenomena were also analysed.The cultures were stressed at high solar irradiance and dissolved oxygenconcentrations. A clear relationship between stress of the cultures and thefluorescence from PSII measurements was observed, the Fv/Fm ratio being lowerinthe helical reactor than in the bubble column. Growth rate and biomassproductivity were both a function of the average irradiance and the Fv/Fmratio;maximum values of 0.040 h^–1 and 0.54 gL^–1 d^–1 were measured. The influenceofphotoinhibition and average irradiance was modelled, the model also fitting theexperimental data reported by another author. The chlorophyll contenthyperbolically decreased, whereas the carotenoid content decreased linearlywiththe average irradiance. The higher the dilution rate the higher the protein andcarbohydrate content of the biomass, and the lower the lipid content. Theeicosapentaenoic acid (EPA) content ranged from 2.3 to 3.2% d.wt, the higherthe dilution rate, the lower EPA content, although the higher the EPAproportion. Maximum EPA productivity was only 9 mg L^–1d^–1, due to the stress to which the cultures wereexposed.     

Genome-wide methylation profiling identifies hypermethylated biomarkers in high-grade cervical intraepithelial neoplasia

Epigenetic modifications, such as aberrant DNA promoter methylation, are frequently observed in cervical cancer. Identification of hypermethylated regions allowing discrimination between normal cervical epithelium and high-grade cervical intraepithelial neoplasia (CIN2/3), or worse, may improve current cervical cancer population-based screening programs. In this study, the DNA methylome of high-grade CIN lesions was studied using genome-wide DNA methylation screening to identify potential biomarkers for early diagnosis of cervical neoplasia. Methylated DNA Immunoprecipitation (MeDIP) combined with DNA microarray was used to compare DNA methylation profiles of epithelial cells derived from high-grade CIN lesions with normal cervical epithelium. Hypermethylated differentially methylated regions (DMRs) were identified. Validation of nine selected DMRs using BSP and MSP in cervical tissue revealed methylation in 63.2–94.7% high-grade CIN and in 59.3–100% cervical carcinomas. QMSP for the two most significant high-grade CIN-specific methylation markers was conducted exploring test performance in a large series of cervical scrapings. Frequency and relative level of methylation were significantly different between normal and cancer samples. Clinical validation of both markers in cervical scrapings from patients with an abnormal cervical smear confirmed that frequency and relative level of methylation were related with increasing severity of the underlying CIN lesion and that ROC analysis was discriminative. These markers represent the COL25A1 and KATNAL2 and their observed increased methylation upon progression could intimate the regulatory role in carcinogenesis. In conclusion, our newly identified hypermethylated DMRs represent specific DNA methylation patterns in high-grade CIN lesions and are candidate biomarkers for early detection.