2-(Bipiperidin-1-yl)-5-(nitroaryl)-1,3,4-thiadiazoles: Synthesis,evaluation of in vitro leishmanicidal activity,and mechanism of action

The development of novel leishmanicidal agents that are capable of being replaced by the available therapeutic options has become a priority. In the present study, the synthesis and leishmanicidal activity of a series of 5-(nitroheteroaryl-2-yl)-1,3,4-thiadiazole derivatives are described. All compounds appeared to be potent anti-leishmanial agents against both promastigote and amastigote forms of Leishmania major (L. major). Amongst the synthesized compounds, 2-([1,4′-bipiperidin]-1′-yl)-5-(5-nitrofuran-2-yl)-1,3,4-thiadiazole (IIa) and 1-(5-(1-methyl-5-nitro-1H-imidazole-2-yl)-1,3,4-thiadiazol-2-yl)-4-(piperidine-1-yl) piperidine (IIc) are the most effective. Infection index was statistically declined in the presence of all compounds. The analysis of redox-related factors revealed that exposure of L. major cells to IIa and IIc led to an increase in reactive oxygen species (ROS). Furthermore, two compounds were able to increase ROS and NO levels in infected macrophages in a dose-independent manner. In addition, we showed that these compounds induced cell death in promastigotes. Altogether, our results indicated the anti-leishmanial potential of IIa and IIc is mediated by apoptosis through an imbalance in the redox system resulting in the elevation of ROS. This new class of compound seems to hold great promise for the development of new and useful anti-leishmanial agents.     

Social contact and hormonal changes predict post-conflict cooperation between friends

Long-term cooperation between individuals necessitates repairing damage arising from inevitable competing interests. How two members of a valuable relationship switch from competing to cooperating constitutes an important problem for any social species. Observations of non-human animals suggest that affiliative contact immediately following a contest facilitates continued cooperation. Behavioral studies further indicate that winners and losers frequently differ in hormonal changes following a competition. We tested the hypothesis that immediate contact with increases in cortisol (and testosterone for men) for winners following competition would facilitate subsequent cooperation between adult same-sex friends. Results show that contact (versus no contact) immediately following competition enhanced subsequent cooperation between female friends. During contact, increases in winner's cortisol for both sexes, and in testosterone for men, predicted future cooperation. Our results suggest two mechanisms that maintain social bonds following competition between established allies.     

Riparian zone as a main determinant of the structure of lizard assemblages in upland Amazonian forests

The use of lizards as model organisms in ecological studies is based on their success in occupying a great diversity of habitats, and some species are closely tied to the environment, which is disadvantaged by the legislation of several countries concerning land use. Our aim was to relate lizard species distribution patterns in rainforest environments to variation in environmental gradients, and provide ecologically based metrics for establishing buffer zones around streams. Lizards were sampled three times in 41 standardised transects near Manaus, Brazil, only in dry season, with Time Limited Visual Search associated with raking through leaf litter. We recorded 20 species from 10 families and used non‐metric multidimensional scaling to reduce the dimensionality of quantitative and qualitative compositions of species. Multiple linear regression models indicated that the environmental gradients distance to nearest stream, extent of canopy openness, vegetation density and slope did not significantly influence assemblage species distribution, with an indication of effect of litter depth. By means of piecewise linear regression, the use of riparian zone was estimated at ~190 m from quantitative species composition and ~211 m from qualitative species composition. Five species occurred only in the riparian zone. Our results suggest that conservation of the entire riparian lizard assemblage in Amazonian rainforest is likely to require protection of at least a 211 m buffer on either side of streams.     

粤东亚热带森林群落树种组成对苔藓植物分布的影响

为探究森林群落树种组成对苔藓植物分布的影响,利用多元统计方法研究粤东亚热带地区苔藓植物的组成和分布对林分类型的响应。根据森林乔木层的树种组成划分为翻白叶树(Pterospermum heterophyllum)、木荷(Schima superba)+米锥(Castanopsis carlesii)和米锥3种森林类型。结果表明,3种森林类型中苔类(liverworts)和藓类(mosses)植物群落组成特征总体上存在显著差异;双齿裂萼苔(Chiloscyphus latifolius)和细指苔(Kurzia gonyotricha)在3种类型林分中的重要值变化指示了苔类植物群落的差异。3种类型林分中,均以东亚拟鳞叶藓(Pseudotaxiphyllum pohliaecarpum)为优势种。不同林分中藓类植物种类组成主要表现为亚优种分布的不同。这表明森林群落树种组成作为重要的生物因子,对林内苔藓植物的分布和种类组成有重要影响。     

小鼠休眠胚胎与正常胚胎冻融后体内外发育潜力的比较

目的检验小鼠休眠胚胎冻融后的质量及体内外发育潜力,为胚胎休眠技术的生产应用提供必要的参考。方法采用常规冷冻方法将正常孵化期胚胎和休眠胚胎进行冷冻,之后分别进行体外复苏培养实验和胚胎移植实验。随后利用双重荧光染色的方法分别对冻融前后的小鼠休眠胚胎与正常孵化期胚胎进行细胞计数,观察两种胚胎冻融前后的质量变化。结果休眠胚胎的冷冻解冻回收率、发育率均极显著高于孵化期胚胎(72.1%vs 50.2%,P<0.01;94.2%vs 73.9%,P<0.01)。休眠胚胎的移植妊娠率显著高于孵化期胚胎(40.8%vs 30.1%,P<0.05)。休眠胚胎的内细胞团细胞数显著高于孵化期胚胎(27.83 vs 19.53,P<0.05),滋养层细胞数差异不显著。冻融培养后休眠胚胎的内细胞团数,滋养层细胞数均显著高于孵化期胚胎(25.18 vs 14.68,P<0.05;114.09 vs 73.88,P<0.05)。结论小鼠休眠胚胎冻融后胚胎质量及体内外发育潜力均优于小鼠正常孵化期胚胎。     

CONTAMINATED LEVEL AND RISK ASSESSMENT OF PAES IN THE UPPER REACHES OF THE YANGTZE RIVER北大核心CSCD

PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

RELATIONSHIPS BETWEEN REPRODUCTION ACTIVITIES OF FISHES WITH DRIFTING EGGS AND ENVIRONMENTAL FACTORS IN THE CHISHUI RIVER北大核心CSCD

The Chishui River is the only undammed first-order tributary of the upper Yangtze River Basin. It is an important part of the “National Nature Reserve for Rare and Endemic Fishes of the Upper Yangtze River”, which plays important roles in fish conservation. To determine main environmental factors that affect the breeding activities of fishes with drifting eggs in this river, investigations on fish resources of early life stages were carried out in Chishui Reach from March to July in 2015 and April to August in 2016. A total of 27 species of fish early resources, belonging to 3 orders, 7 families and 22 genera, were collected during the investigation period. Nine of these species Pseudolaubuca engraulis, Squalidus argentatus, Gobiobotia filifer, Botia superciliaris, Parabotia fasciata, Parabotia bimaculata, Leptobotia elongate, Leptobotia taeniops and Lepturichthys fimbriata laid drifting eggs in the running water. Canonical Correspondence Analysis (CCA) revealed various breeding environmental requirements for these species. Specially, B. superciliari, P. fasciata, P. bimaculata, L. elongate, L. taeniops and L. fimbriata tended to lay eggs when the water discharge was increasing, while P. engraulis and S. argentatus showed an opposite trend. Additionally, G. filifer preformed differently between 2015 and 2016. In the low flow year, their reproductive activities were positively associated with the water discharge. However, in the high flow year, no significant relation between the reproduction activities and water discharge was observed. These results strengthen our understanding of reproductive behavior of different fish species and provide valuable insights into fish conservation. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

THE YANGTZE RIVER-FLOODPLAIN ECOSYSTEM: MULTIPLE THREATS AND HOLISTIC CONSERVATION北大核心CSCD

The Yangtze (Changjiang) river-floodplain is one of the most important ecosystems in China and the world, but is seriously threatened by multiple stresses. Thus, it is crucial and urgent to rehabilitate and conserve the river-floodplain. This paper reviews ecological studies conducted on the Yangtze river-floodplain, and presents suggestions for conservation and rehabilitation. First, basic concepts and research advances of riverscape and hydrological connectivity are introduced. Second, the history and current status of the Yangtze River system are summarized. Before 23 Ma, the Yangtze River cut through the Three Gorges, forming the river much like the modern one. Numerous rivers, streams, lakes (the total area 15770 km2 at present) and wetlands are distributed in the mid-lower Yangtze river-flood-plain. Such a river-lake complex ecosystem holds a unique and diverse biota, and is the most important fishery area of China. Third, main threats to the Yangtze river-floodplain ecosystem are identified, i.e., a) habitat loss, including river channelization, sharp shrinkage of lake area (ca. 10000 km2 since the 1950s), degradation of lakeshore zones and sand over-mining; b) alternations of hydrological regimes, including construction of ca. 47000 reservoirs and disconnection of most lakes from the mainstem; c) water pollution, including eutrophication, heavy metals, organic pollutants and microplastic; d) overexploitation of biological resources, including overfishing and intensive pen culture. Fourth, effects of river-lake disconnection on lake ecosystems are summarized. It was found that a) disconnection is one of the main causes of lake eutrophication; b) species diversity, biomass, production of macrophytes and macrobenthos reach maxima at some levels of intermediate river connectivity; c) disconnection greatly reduces fish species richness of each habitat guild, and natural fish larvae is severely depleted; d) disconnection simplifies macroinvertebrate food web structure, and trophic basis is more heavily relied on detritus in disconnected lakes. Last, conservation strategies are proposed. Since the Yangtze river-floodplain is a huge integrated system, the biodiversity conservation must be conducted on the whole basin scale. By establishing species-area models of fishes, the minimum protected area of Yangtze-connected lakes is estimated to be ca. 14400 km2. It means that at least 8900 km2 of disconnected lakes should be reconnected with the Yangtze mainstem, and ecohydrological operation of dams and sluices is the feasible approach. Based upon our studies on environmental flow requirements, the following measures are suggested: a) lower water levels during spring to improve germination of macrophytes, and control rising rates of water levels during spring-summer to ensure development of macrophytes; b) open sluice gates to restore migration routes for juveniles migrating into lakes during April-September, and for adults migrating back to the Yangtze mainstem during November-December. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.