Lemna minor is a species easy to collect and culture in laboratory, and can give rapid test results. However, in order to standardise toxicity tests using Lemna minor as test organism, it is important to find out what natural variability different populations might have. Five Lemna populations were used for comparison. It contained two standard cultures and three populations collected in natural habitats. Potassium dichromate was applied as test material. Lemna populations cultured under the same condi- tions showed different TD and LC50 values. There is an inverse relation between the sensitivity and TD of the strains. It is supposed that growth rate and sensitivity of Lemna populations depend on environmen- tal factors characterising the habitat in which the given popluation originally lives.
Authors:Nóra Kováts, L. Füle, I. Magyar, Tímea Szalay and I. Kiss
During the analysis of environmental risk posed by hazardous waste disposal sites, ecological impact on whole ecosystems should be assessed. It requires a complex testing scheme where surrogate species represent key elements of the ecosystem. However, different organisms are exposed to a differing degree, also, their sensitivity to the same contaminant may vary. A possible way to determine which test reflects most the actual toxic conditions, correlation can be calculated between the measured ecological parameter (such as growth inhibition, mortality, etc.) and a contaminant gradient. The basic aim of this study was to determine which ecotoxicological test shows the best correlation with the measured analytical parameters. The selected tests were Lemna minor (representing primary producers), Thamnocephalusplatyurus (a primary consumer organism) and Vibrio fischeri (decomposer). When testing soil samples, the Thamnocephalus test showed excellent consistency with most contaminants but was oversensitive in the case of groundwater samples. The Vibriofischeri bioluminescence inhibition test (ToxAlert) behaved in a different way, reflecting well the distribution of most contaminants in groundwater samples. Finally, Lemna test proved to be completely inadequate.
Sudan is suffering from harsh summers, but most of the modern buildings in urban areas are not compatible with the recent and future climate phenomena. Application of cooling devices is relatively expensive and therefore beyond reach. The main objective of this research is to give an overview on the overheating problem and the thermal comfort in buildings. A dynamic energy simulation has been performed for a selected case study using Design Builder Code. The results show that the share of discomfort hours for a typical modern building is 78% and 33% above 26 °C and 32 °C per year, respectively, but after using a combination of different ventilation, shading and building materials options the discomfort hours can be reduced to 77% and 26%, respectively.
Authors:Gábor Takács, Cs. Szalay, B. Nagy, I. Szabó, D. Simon, T. Berki and Z. Karádi
The nucleus accumbens (NAcc), an important basal forebrain structure, has a central integratory function in the control of feeding and metabolism. The primary cytokine interleukin-1β (IL-1β) exerts its neuromodulatory effects on the endocrine functions both centrally and peripherally. The present study was designed to elucidate the possible consequences of direct administration of IL-1β into the NAcc on the endocrine regulation of metabolism. Plasma concentrations of insulin and leptin, two key hormones in the homeostatic control were determined 15 minutes after a single bilateral microinjection of IL-1β into the NAcc of adult male Wistar rats, and the effects were compared with those found in vehicle treated control animals. Insulin plasma levels of the cytokine treated animals were significantly higher than those parameters of the control rats. No differences were found in leptin plasma concentrations between the two groups. Our findings show that IL-1β mediated processes in the NAcc have important roles in the central neuroendocrine control.