Impact of the toxicity of Cylindrospermopsis raciborskii (Woloszynska) Seenayya & Subba Raju on laboratory rats in vivo

In vivo laboratory studies of toxicity were performed on Wistar rats using a methanol extract produced by the natural population of Cylindrospermopsis raciborskii (abundance of 2.13 × 10⁵ trichomes mL⁻¹) collected at Aleksandrovac Lake (Serbia). HPLC analysis showed that the extract contains 6.65 μg cylindrospermopsin (CYN) mg⁻¹. The rats were killed 24 or 72 h after a single intraperitoneal injection of C. raciborskii extract in concentrations of 1500, 3000, 6000 and 12,000 μg kg⁻¹ body weight (bw) and an equivalent amount of CYN as present in the highest dose of the extract (79.80 μg CYN kg⁻¹ bw). The genotoxic effect on the livers treated with C. raciborskii was evaluated using comet assay and potential induction of oxidative stress as the toxicity mechanism associated with the presence of CYN in extract. The results from the analyses of DNA damage in the comet tail length, tail moment and percentage of DNA in the tail in the liver indicated that administration of extract and CYN present statistically significant difference when compared with the negative control group. Although an increase in the frequency of selected parameters induced by the CYN was observed in the liver, this damage was less than the damage resulting from the administration of the highest dose of extract. The changes in the biochemical parameters of the hepatic damage showed that the application of single doses of the extract and CYN did not cause serious liver damage in rats. The extract and CYN significantly increased oxidative stress in rats’ liver after a single exposure.

     

Linguistic diversity and conservation opportunities at UNESCO World Heritage Sites in Africa

Africa contains much of Earth's biological and cultural–linguistic diversity, but conserving this diversity is enormously challenging amid widespread poverty, expanding development, social unrest, and rapidly growing human population. We examined UNESCO (United Nations Educational, Scientific and Cultural Organization) Natural World Heritage Sites (WHSs) on continental Africa and nearby islands—48 protected areas containing globally important natural or combined natural and cultural resources—to gauge the potential for enlisting Indigenous peoples in their conservation. We used geographic information system technology to identify instances where Natural WHSs co-occur with Indigenous languages, a key indicator of cultural diversity. And, we compared the geographic ranges for 4 taxa and selected freshwater species with occurrence of all Indigenous languages within Natural WHSs and subsections of WHSs covered by the geographic extent of Indigenous languages to measure the correlation between linguistic and biological diversity. Results indicated that 147 languages shared at least part of their geographic extent with Natural WHSs. Instances of co-occurrence where a WHS, a language, or both were endangered marked localities particularly deserving conservation attention. We examined co-occurrence of all languages and all species, all languages and endangered species, and endangered languages and endangered species and found a correlation between linguistic and biological diversity that may indicate fundamental links between these very different measures of diversity. Considering only endangered species or endangered languages and species reduced that correlation, although considerable co-occurrence persisted. Shared governance of government-designated reserves is applicable for natural WHSs because it capitalizes on the apparent connection between culture and nature. Natural WHSs in Africa containing speakers of Indigenous languages present opportunities to conserve both nature and culture in highly visible settings where maintaining natural systems may rely on functioning Indigenous cultural systems and vice versa.     

An investigation of aqueous activity coefficients at low concentrations

The activity of a chemical in solution determines its tendency to move into other media. At low concentrations (<0.01M) it is generally considered to be linearly related to concentration. A hypothetical model based on the structure of liquid water is discussed which could cause deviations from this linearity in the ppb region, a concentration much lower than that normally investigated thermodynamically, but one of great importance environmentally. Headspace experiments are reported with carbon tetrachloride and chloroform in water at concentrations down to ～10^?3 ppb but no such deviations were discerned.     

油浸变压器排油注氮装置在500kV变电站的设计与应用

在分析500kV变电站主变压器消防系统的现状,比较3类消防系统优缺点的基础上,详细论述了主变排油注氮装置的结构组成、工作原理、参数计算、控制系统设计以及需要注意的事项等,为下一步排油注氮装置的推广应用打下基础.     

Agricultural capacity and conservation in high biodiversity forest ecosystems

Agricultural development is a leading cause of habitat destruction that increasingly threatens global biodiversity. To help understand the likelihood and implications of agricultural expansion in areas of high conservation importance, this article examines agricultural suitability in forested portions of biodiversity hotspots and tropical wilderness areas, regions with especially rich concentrations of species found nowhere else. The study employs geographic information system technology to examine suitability for six crop categories in selected conservation localities worldwide: those portions of regions containing high biodiversity, protected areas (e.g. national parks) within these regions, and 10-km bands around the protected areas that are dominated by forest. Analyses reveal low suitability for most crop categories under both commercial and subsistence scenarios, with a few exceptions. In most cases, adequate planning can enable the coexistence of agriculture and biodiversity without compromising either.