Pulvinus activity,leaf movement and leaf water-use efficiency of bush bean (<Emphasis Type="Italic">Phaseplus vulgaris</Emphasis> L.) in a hot environment

Pulvinus activity of Phaseolus species in response to environmental stimuli plays an essential role in heliotropic leaf movement. The aims of this study were to monitor the continuous daily pulvinus movement and pulvinus temperature, and to evaluate the effects of leaf movements, on a hot day, on instantaneous leaf water-use efficiency (WUE_i), leaf gas exchange, and leaf temperature. Potted plants of Phaseolus vulgaris L. var. Provider were grown in Chicot sandy loam soil under well-watered conditions in a greenhouse. When the second trifoliate leaf was completely extended, one plant was selected to measure pulvinus movement using a beta-ray gauging (BRG) meter with a point source of thallium-204 (²⁰⁴Tl). Leaf gas exchange measurements took place on similar leaflets of three plants at an air temperature interval of 33–42°C by a steady-state LI-6200 photosynthesis system. A copper-constantan thermocouple was used to monitor pulvinus temperature. Pulvinus bending followed the daily diurnal rhythm. Significant correlations were found between the leaf-incident angle and the stomatal conductance (R ² = 0.54; P < 0.01), and photosynthesis rate (R ² = 0.84; P < 0.01). With a reduction in leaf-incidence angle and increase in air temperature, WUE_i was reduced. During the measurements, leaf temperature remained below air temperature and was a significant function of air temperature (r = 0.92; P < 0.01). In conclusion, pulvinus bending followed both light intensity and air temperature and influenced leaf gas exchange.     

Differential protein synthesis after red light illuminations in germinating fern spores

The effects of red and far red illuminations were studied in spores of the dark germinatingPteridium aquilinum and that of the light dependently germinatingDryopteris filix-mas. Proteins were analysed by electrophoresis according to their molecular weights. The isoesterases were separated by gel electrofocusing. In both species we found two newly synthesized protein bands, probably controlled by the presence of active phytochrome. One of these seems to be identical, the other is different in the two species. Phytochrome control was also detected in the esterase isoenzyme pattern.     

Urethane and hydroxyurethane induce sister-chromatid exchanges in cultured human lymphocytes.

Both urethane and hydroxyurethane induced sister-chromatid exchanges (SCE) in cultured human lymphocytes. Aroclor-induced rat-liver microsome fraction deactivated rather than activated these two agents in the lymphocyte system.     

Temporal variation in juvenile fish communities of Kaunas reservoir littoral zone,Lithuania

The aim of this study was to assess juvenile fish communities in terms of species composition, fish diversity and density in the littoral zone of the Kaunas reservoir before (in 1989–1990, period I) and after (in 1999–2000, period II, and in 2006–2007, period III) launching the Kruonis hydroelectric pumped plant (Kruonis HPP). During the whole research period, 20 fish species were caught. According to the frequency of occurrence, the three-spined stickleback Gasterosteus aculeatus, European perch Perca fluviatilis and roach Rutilus rutilus were regarded as constant species in all investigated periods. Significant differences were established in juvenile fish community density between period I and periods II and III, whereas species richness (S) and species diversity indices (H′, J′) did not change significantly. The density of the shoreline community in period III was more than two times lower than in period I, probably due to higher fluctuations in water level of the reservoir, resulting from the Kruonis HPP operation.     

Probing the conformational changes and peroxidase-like activity of cytochrome c upon interaction with iron nanoparticles

Herein, the interaction of iron nanoparticle (Fe-NP) with cytochrome c (Cyt c) was investigated, and a range of techniques such as dynamic light scattering (DLS), zeta potential measurements, static and synchronous fluorescence spectroscopy, near and far circular dichroism (CD) spectroscopy, and ultraviolet–visible (UV–vis) spectroscopy were used to analyze the interaction between Cyt c and Fe-NP. DLS and zeta potential measurements showed that the values of hydrodynamic radius and charge distribution of Fe-NP are 83.95 ± 3.7 nm and 4.5 ± .8 mV, respectively. The fluorescence spectroscopy results demonstrated that the binding of Fe-NP with Cyt c is mediated by hydrogen bonds and van der Waals interactions. Also Fe-NP induced conformational changes in Cyt c and reduced the melting temperature value of Cyt c from 79.18 to 71.33°C. CD experiments of interaction between Fe-NP and Cyt c revealed that the secondary structure of Cyt c with the dominant α-helix structures remained unchanged whereas the tertiary structure and heme position of Cyt c are subjected to remarkable changes. Absorption spectroscopy at 695 nm revealed that Fe-NP considerably disrupt the Fe…S(Met80) bond. In addition, the UV–vis experiment showed the peroxidase-like activity of Cyt c upon interaction with Fe-NP. Hence, the data indicate the Fe-NP results in unfolding of Cyt c and subsequent peroxidase-like activity of denatured species. It was concluded that a comprehensive study of the interaction of Fe-NP with biological system is a crucial step for their potential application as intracellular delivery carriers and medicinal agents.