Expression of a barley cystatin gene in maize enhances resistance against phytophagous mites by altering their cysteine-proteases

Phytocystatins are inhibitors of cysteine-proteases from plants putatively involved in plant defence based on their capability of inhibit heterologous enzymes. We have previously characterised the whole cystatin gene family members from barley (HvCPI-1 to HvCPI-13). The aim of this study was to assess the effects of barley cystatins on two phytophagous spider mites, Tetranychus urticae and Brevipalpus chilensis. The determination of proteolytic activity profile in both mite species showed the presence of the cysteine-proteases, putative targets of cystatins, among other enzymatic activities. All barley cystatins, except HvCPI-1 and HvCPI-7, inhibited in vitro mite cathepsin L- and/or cathepsin B-like activities, HvCPI-6 being the strongest inhibitor for both mite species. Transgenic maize plants expressing HvCPI-6 protein were generated and the functional integrity of the cystatin transgene was confirmed by in vitro inhibitory effect observed against T. urticae and B. chilensis protein extracts. Feeding experiments impaired on transgenic lines performed with T. urticae impaired mite development and reproductive performance. Besides, a significant reduction of cathepsin L-like and/or cathepsin B-like activities was observed when the spider mite fed on maize plants expressing HvCPI-6 cystatin. These findings reveal the potential of barley cystatins as acaricide proteins to protect plants against two important mite pests

Seasonal variation of radon in the Bozkov cave

Measurement of the radon concentration has been performed in the Bozkov dolomite cave since 2002. Radon concentration was obtained by two means: continuous measurement by a Radim3 monitor at 30 min intervals and a 6 month average by LR115 solid-state nuclear track detector (SSNTD) in a diffusion chamber placed at 8 points along the cave tour path. The radon concentration shows diurnal, seasonal, and yearly variations. The concentration maximum in the cave, in contrast to the dwellings, occurs in the summer time and equals to thousands of Bq/m3. At the same time, high variability of radon concentration occurs. Statistical analysis of a long time series of radon concentration was performed and the meteorological data were taken into account. The annual effective dose from radon for the cave guide (2006 y, working time spent in the cave 414 h) was 3.05 mSv. The dose was calculated using the mean value of radon concentration obtained by SSNTD as written above

Environmental and radon measurements in the underground workplaces in the Czech Republic

Most of radon and other environmental measurements were carried out in connection with research focused on improvement of radon dose assessment in the underground workplaces in the Czech Republic. The following methods are very useful for the detection of radon sources: air flow measurement; continual and short volume activity of radon and its progeny measurement; volume activity of thoron measurement; mapping of radon level in all workplace areas including horizontal and vertical gradient; radon in water measurement; integral radon monitor RAMARN testing, etc. In conjunction with equilibrium radon concentration (ERC) monitoring studies were conducted of radiogenic characteristics of caves clastogene and carbonate sediments, and other rock formations present in the Czech Massif and Western Carpathian. Over 150 samples of cave sediments were collected, in which the mass activities of present radionuclides were determined. Spectrometric analysis of the sediments enabled monitoring of disturbance in secular radioactive equilibrium in the given geochemical systems, through evaluation of 238U/226Ra or 228Th/224Ra proportion. Ratio of 208Tl/226Ra was monitored for the rock groups from the origin point of view assessment. Typical values for such ratio for carbonate rocks (including amphibolite and erlan) varied between 0.2–0.5, while for clastogene sediments and crystalline limestone the typical values were in the range 1.4–1.6. Conclusions from measurements were implemented in the new methodology for radon dose assessment