Radical Intermediates in the Redox Reactions of Tetrazolium Salts in Aprotic Solvents (Cyclovoltammetric, EPR and UV-VIS study)

Tetrazolium Blue (TBCl₂) and Nitrotetrazolium Blue (NTBCl₂) cathodically reduced in non aqueous solvents form radicals with the center of unpaired electron on the tetrazolyl ring (TBH₂, NTBH₂) as detected by EPR spectroscopy. After prolonged reduction, formazans (TBH₂, NTBH₂) are formed and are then further reduced to the nitro-centered anion radical (from NTBH₂) and the azogroup-centered anion radical (from TBH₂). The first cathodic peak in the cyclovoltammetric study in the region from -0.3 to -0.6 V vs. SCE (saturated calomel electrode) is irreversible and indicates an adsorption and diffusion process on the platinum and mercury electrodes. Formation of TBH⁺ and NTBH⁺ is assumed. The second peak, in the region from -0.8 to -1.3 V vs. SCE, is nearly reversible and coupled with the formation of TBH- and NTBH- radicals. UV-VIS spectra measured during the reduction show isosbestic points at the conversions: TB⁺⁺ → TBH⁺, NTB⁺⁺ - NTBH⁺; further, TBH⁺ → TBH₂ and NTBH⁺ → NTBH₂. The characteristic colours of the solutions observed can be used to characterise the reduction state of tetrazolium salts.     

Effects of diet and temperature on Morimus funereus larval hemolymph cation concentrations

The effects of diet and different constant temperatures on hemolymph cation concentrations (Na⁺, K⁺, Mg²⁺, Ca²⁺) have been studied in Morimus funereus larvae collected from natural habitat, fed natural (oak or beech bark) or artificial diet, as well as in larvae reared from hatching on an artificial diet. In the hemolymph of larvae maintained under natural conditions Mg²⁺ was dominant, whereas Na⁺ concentration was very low. In their natural diets concentrations of Na⁺ and K⁺ were very low, while those of Ca²⁺ and Mg²⁺ were high. In larvae continuously reared on an artificial diet, hemolymph Mg²⁺ concentration was significantly decreased and Na⁺ concentration increased more than fourfold compared to the results obtained in oak-fed larvae. Na⁺ and K⁺ are the dominant cations in the artificial diet. The concentrations of K⁺ and Ca²⁺ in the hemolymph of larvae fed natural or artificial diet are nearly identical, suggesting the existence of an internal regulatory mechanism in this insect for these cations. The hemolymph cation concentrations of M. funereus larvae are predominantly dependent upon the diet consumed, much less upon the environmental temperatures. The most stable concentrations of cations were observed in larvae continuously fed an artificial diet and exposed to different constant temperatures. There was much less stability in the hemolymph cation concentration in oak larvae fed either natural or artificial food after their transfer to constant temperatures. With respect to the response to the external factors studied, the most sensitive are the Na⁺ concentrations, the most stable seems to be K⁺. © 1992 Wiley-Liss, Inc.     

A reconstruction of the Late-Glacial and Early-Holocene evolution of forest vegetation in the Poprad Basin,Czechoslovakia

Jankovská V. (1988): A reconstruction of the Late-Glacial and Early-Holocene evolution of forest vegetation in the Poprad Basin, Czechoslovakia.—Folia Geobot. Phytotax., Praha, 23: 303–319. —A profile of a carbonate fen sediment coming from the vicinity of the village Hozelec (3 km SE of Poprad—High Tatra, in the Poprad Basin) was elaborated using pollen analysis. The Late Glacial and Early Holocene Periods were recorded in detail. Due to low pollen frequency and damaged pollen grains, the vegetation development in the Middle and Late Holocene Periods was recorded only in fragments. The estimated age of the samples, i.e. Alleröd, Pre-Boreal/Boreal and Boreal/Atlantic Period, was supported by radiocarbon (C-14) dating. The results represent an objective proof of the reafforestation of the area under study by stands ofLarix, Pinus cembra andP. sylvestris, at the end of the last Glacial Period as early as Older Dryas (Early Weichselian). The maximum development of theLarix stands took place in Alleröd. The early emergence ofPicea between the Younger Dryas (Late Weichselian) and Pre-Boreal Periods points to the existence of glacial refugia of this tree in the neighbourhood. Finds of the conches of molluscs were also determined. A survey of the results of pollen analyses from other pollenanalytically and macroacopically elaborated localities in the north-western part of the Carpathians is presented.     

Long-term vegetation dynamics and the infilling process of a former lake (Švarcenberk, Czech Republic)

Natural lakes are a rare phenomena within extraglacial areas of Central Europe. Almost all have been completely terrestrialized during the Holocene. This paper deals with one such former lake, located in southern Bohemia. Its extensive lacustrine and peat deposits were subjected to a multidisciplinary study that resulted in high-resolution pollen, macrofossil, algal and sediment-chemistry data interpreted in terms of past climate, geomorphology, soil, and regional vegetation development over the last 16,000 years. Against the background of these large-scale processes, local development took place, comprising the lake’s ontogeny from an arctic-type ecosystem hosting pioneer aquatic communities, through a highly diversified mosaic of eutrophic hydrosere habitats (shallow pools,Phragmites andCarex fen, alder carr), towards an oligotrophic mire that started to dome over the terrestrialized lake. At every individual development stage, specific processes characterized ecosystem function and composition: during the Late-Glacial with its rapid climatic changes, external forces induced the major stresses; while during the Holocene, autogenic changes of the wetland ecosystem played the most important role.     

Serum selenium in adult Czechoslovak (central bohemia) population

The serum selenium levels in 367 healthy adult (25–64 yr) Central Bohemia residents, 176 men and 191 women, were determined using atomic absorption spectrometry. An extremely wide range of values was found in the whole population sample (<20–296 μg/L) as well as in each sex or age category studied. The mean selenium concentration and 95% confidence interval calculated after logarithmic transformation of the data were 74 μg/L (71–77) for the whole population sample, 72 μg/L (67–76) for men, and 76 μg/L (72–81) for women. About 10% of the residents exhibited serum selenium level below 45 μg/L. There was no significant correlation between serum selenium and sex, age, or smoking status of participants. However, the lowest average level was found in the group of heavy smoking women: 66 μg/L. The selenium status of the Central Bohemia population seems to be below European average. Groups of residents having a very low nutritional selenium intake may be expected to occur in this population. Dedicated to the memory of Jiří Pařízek, former head of environmental physiology research group of the Institute of Nuclear Biology and Radiochemistry.     

The Croatian Adult Health Cohort Study (CroHort) --background, methodology & perspectives

Health interview surveys are important source of health information. All previous adult population-based health interview surveys in Croatia until CroHort, were one-off projects with very limited possibility of data comparison. CroHort enabled repeated survey of CAHS 2003 respondents with almost identical questionnaire, thus providing comparable data on trends of different risk factors as well as their relation to the specific outcomes. Next follow-up survey of the CroHort cohort is foreseen for 2013. Health interview survey according to Eurostat methodology (EHIS) on the new representative sample of adult Croatian population is planned for 2014. As the data from health interview surveys are valuable in health policy, efforts should be made to increase their use by policymakers in Croatia.     

Screening of mutant strain Streptomyces mediolani sp. AC37 for (−)-8-O-methyltetrangomycin production enhancement

Streptomyces mediolani sp. AC37 was isolated from the root system of higher plant Taxus baccata and produced metabolite identified as (?)-8-O-methyltetrangomycin according to LC/MS/MS analysis. In our screening program for improvements of bioactive secondary metabolites from plant associate streptomycetes, mutation was used as a tool for the induction of genetic variations for selection of higher (?)-8-O-methyltetrangomycin producers of isolates. S. mediolani sp. AC37 was treated with UV irradiation and chemical mutagenic treatment (N-nitroso-N-methyl-urea). The radical scavenging and antioxidant capacity of (?)-8-O-methyltetrangomycin and extracts isolated from mutants were tested using EPR spin trapping technique and ABTS^·+ assay. Comparison of electron microscopic images of Streptomyces sp. AC37 and mutant strains of Streptomyces sp. AC37 revealed substantial differences in morphology and ultrastructure.