Morphogene substanzen ausHydra

We use hydra as a model system to understand how growth and differentiation and, as a consequence of this, pattern formation are controlled at the molecular level. We have found that four substances control head and foot formation in hydra: an activator and an inhibitor of head formation and an activator and an inhibitor of foot formation. The two activators are peptides with molecular weights around 1000 daltons, the inhibitors are smaller in molecular weight (<500), have an overall positive charge and do not contain peptide bonds. In normal animals all four substances are present and most likely produced by nerve cells. We hope to understand how these substances act and interact to create the spatial and temporal pattern of growth and differentiation typical for hydra.     

新疆煤田火灾的成因、危害及综合治理

新疆是世界上煤田火灾最严重的地区,原因主要是新疆地处欧亚大陆腹地,具典型的大陆性干旱气候;新疆地区煤系为中下侏罗纪,地质活动较为剧烈;小煤窑的乱采滥挖等.新疆煤田火灾带来巨大危害:损失煤炭资源、污染环境、引发地质灾害、破坏生态平衡及危害生物健康等.对煤田火灾进行综合治理已经成为当务之急.为了有效灭火,应先对火区进行探测.探测方法有磁异常探测法、自然电场法和红外地面测温法等.然后因地制宜地选择适当的灭火技术进行灭火.灭火之后还应利用地理信息系统等方法对火区进行动态监测.     

The importance of glutathione and phytochelatins on the selenite and arsenate detoxification in Arabidopsis thaliana

We investigated the role of glutathione(GSH) and phytochelatins(PCs) on the detoxification of selenite using Arabidopsis thaliana. The wild-type(WT) of Arabidopsis thaliana and its mutants(glutathione deficient Cad 2–1 and phytochelatins deficient Cad 1–3) were separately exposed to varying concentrations of selenite and arsenate and jointly to both toxicants to determine their sensitivities. The results of the study revealed that, the mutants were about 20-fold more sensitive to arsenate than the WT, an indication that the GSH and PCs affect arsenate detoxification. On the contrary, the WT and both mutants showed a similar level of sensitivity to selenite, an indication that the GSH and PCs do not significantly affect selenite detoxification. However, the WT is about 8 times more sensitive to selenite than to arsenate, and the mutants were more resistant to selenite than arsenate by a factor of 2. This could not be explained by the accumulation of both elements in roots and shoots in exposure experiments. The co-exposure of the WT indicates a synergistic effect with regards to toxicity since selenite did not induce PCs but arsenic and selenium compete in their PC binding as revealed by speciation analysis of the root extracts using HPLC–ICP–MS/ESI–MS. In the absence of PCs an antagonistic effect has been detected which might suggest indirectly that the formation of Se glutathione complex prevent the formation of detrimental selenopeptides. This study, therefore, revealed that PC and GSH have only a subordinate role in the detoxification of selenite.     

Heavy metals and arsenic fixation into freshwater organic matter under Gammarus pulex L. influence

Organic sediments are a main sink for metal pollutants in aquatic systems. However, factors that make sediments a sink of metals and metalloids are still not clear. Consequently, we investigate the role of invertebrate shredders (Gammarus pulex L.) on quality of metal and arsenic fixation into organic partitions of sediment in the course of litter decay with laboratory microcosm experiments. During the decomposition of leaf litter, G. pulex significantly facilitated the development of small particles of organic matter. The capacity of metal fixation was significantly higher in smaller particles than leaf litter and litter residuals. Thus, G. pulex enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount smaller particles in the aquatic system. Furthermore, invertebrates have a significant effect on formation of dissolved organic matter and remobilization of cobalt, molybdenum and cesium, but no significant effect on remobilization of all other measured elements.     

Enhanced metal and metalloid concentrations in the gut system comparing to remaining tissues of Gammarus pulex L

Invertebrate shredders such as Gammarus pulex are key species in contaminated stream ecosystems. Although a number of previous studies examining differences in metal accumulation between the gut system and remaining tissues of invertebrates exist, few focus on wide range of metals and metalloids that are relevant to contaminated systems. This study compared accumulation of the commonest (at study site) 15 metals and metalloids between the gut system including feces and remaining tissues of G. pulex. All metals and metalloids measured were significantly higher (p<0.001, except Cu p<0.005) in the gut system including feces than remaining tissues of G. pulex. Metals and metalloids in body tissues without the gut system including feces were significantly lower (Al, Cr, Fe and Mn (p<0.005), Sr and U (p<0.01), Co (p<0.05)) in content for a number of elements when compared to washed, whole G. pulex specimens. As well, all elements measured were significantly higher (all elements (p<0.005) except Cu and Co (p<0.05)) in gut system including feces than washed, whole G. pulex specimens. These results indicate that in G. pulex the uptake of all 15 metals and metalloids examined across the gut epithelium is minimalized or that sequestration of these elements in gut epithelial cells may occur.