Elaborations of the basal surface of the cells of the Malpighian tubules of an insect

Electrical measurements of membrane potential and resistance using intracellular microelectrodes showed that the fluid-secreting parts of the Malpighian tubules of Rhodnius have superficial regions different in electrical properties from the main body of the cell. The membrane potential in these superficial regions was smaller by 30-40 mV, but showed a standard depolarization on changing the potassium concentration of the bathing medium. The response to changes in the external chloride concentration also differed in the two regions, a finding that was reinforced by different responses to the drug, furosemide. Electron microscopy of the basal regions of the cells revealed many long cellular projections that run parallel to the cell surface and interdigitate with similar projections from neighbouring cells. The degree of interdigitation was examined by marking individual cells with alcian blue or by horseradish peroxidase injection. A survey of the published micrographs of insect Malpighian tubules shows that most have similar projections on their basal surfaces and not the simple basal infoldings previously supposed.     

九种蹄盖蕨科植物配子体的酯酶同工酶分析

本文培养了蹄盖蕨科９个种即中华蹄盖蕨（Ａｔｈｙｒｉｕｍｓｉｎｅｎｓｅ）带岭蹄盖蕨（Ａ．ｄａｌｉｎｇｅｎｓｅ）、多齿蹄盖蕨（Ａ．ｍｕｌｔｉｄｅｎｔａｔｕｍ）（包括青柄和紫柄２种带岭蹄蕨类型）、东北蛾眉蕨（Ｌｕｎａｔｈｙｒｉｕｍｐｙｃｎｏｓｏｒｕｍ）、朝鲜介蕨（Ｄｒｙｏａｔｈｙｒｉｕｍｃｏｒｅａｎｕｍ）、山冷蕨（Ｃｙｓｔｏｐｔｅｒｉｓｓｕｄｅｔｉｃａ）、假冷蕨（Ｐｓｅｕｄｏｃｙｓｔｏｐｔｅｒｉｓｓｐｉｎｕｌｏｓａ）、欧洲羽节蕨（Ｇｙｍｎｏｃａｒｐｉｕｍｄｒｙｏｐｔｅｒｉｓ）和黑鳞短肠蕨（Ａｌａｎｔｏｄｉａｃｒｅｎａｔａ）的配子体为材料,进行酯酶同工酶的分析,以表明它们的种间差异,其中多齿蹄盖蕨的青柄和紫柄两种类型的酶谱存在明显差异,应考虑紫柄为多齿蹄盖蕨的变型。     

中国生态环境区划初探

中国生态环境区划初探高密来（中国人民大学区域经济研究所北京１００８７２）ＡｎＡｐｐｒｏａｃｈｔｏｔｈｅＲｅｇｉｏｎａｌｉｚａｔｉｏｎｏｆＥｃｏｌｏｇｉｃａｌＥｎｖｉｒｏｎｍｅｎｔｉｎＣｈｉｎａ．￥ＧａｏＭｉｌａｉ（ＩｎｓｔｉｔｕｔｅｏｆＲｅｇｉｏｎａ...     

Hidden areas of endemism: Small units in the South-eastern Neotropics

This study aimed to establish if the Lower Río de la Plata Basin (LRPB) wetlands can be considered a biogeographic unit. The species of this area were compiled and segregated according to the habitat, selecting only 87 endemic taxa restricted to the LRPB and linked to wetlands. Distributional data of species obtained from the literature, web databases, biological collections, and field trips were georeferenced. The areas of endemism were established as those areas where the distribution of two or more taxa overlaps in groups of rivers’ sections with geographic continuity and were tested with a cluster analysis. This congruence is due to ecological, geomorphological, and historical factors. Four areas of endemism were found: a broad area that comprises the whole study area (Riverine district), which is divided into three nested smaller areas (Paraguay–Paraná Flooding Valleys, Uruguay Basin, and Paraná Delta subdistricts). Then, we analysed 170 taxa distributions to evaluate the relationship between the study area and the neighbouring biogeographic units. According to the results, the study area belongs to the Paraná biogeographic province. Some areas of endemism are hidden inside broader areas and are hardly detected with the currently used biogeographic grid-methods. We propose to combine the information about ecological requirements of each taxon with its georeferenced records to estimate their areas of distribution as a primary step for searching areas of endemism in intracontinental studies.     

中国地貌区划系统——以自然保护区体系建设为目标

地貌类型是重要的自然地理特征,是影响区域生物多样性空间格局变化的重要因子。地貌研究能使人们深入认识地理环境特点,有利于完善对区域自然环境和地域分异规律的认识,同时对生物地理区划和区域自然保护研究也具有很好的参考价值。采用"自上而下"的区域分割和"自下而上"的区域合并的区划方式,以中国地形DEM作为基础,使用GIS10.0对其进行高程重分类、坡度分析等量化分析,并结合现有气候区划、自然地理区划和地貌类型等资料,对中国地貌格局进行了分析。在考虑生物多样性保护过程中以地貌为主体的地理单元差异性基础上,根据分析结果,提出了以区域自然保护区体系构建为目标的中国地貌区划系统,该地貌区划系统包括了东部季风淋蚀地貌大区、西北干燥风蚀地貌大区、青藏高原高寒冻蚀地貌大区、南海诸岛地貌大区等4个地貌大区,大兴安岭、小兴安岭和内蒙古高原等40个地貌地区,完达山、老爷岭和张广才岭等127个地貌亚地区,以及473个地貌区。其地貌区划方案科学构建了区划等级系统,体现了中国地貌类型的基本特征和分布格局,其中地貌大区基本反映了中国大的地貌格局,地貌地区基本反映了高原、山地、平原等地貌特征的水平分异,地貌亚地区和地貌区基本反映了区域地貌特征。中国地貌区划系统为自然保护区体系构建提供了参考和依据,而且区划界线准确,便于使用。     

基于遥感和GIS的巢湖流域生态功能分区研究

生态功能分区是区域自然资源科学管理及可持续发展利用的基础。基于生态功能分区原则,考虑流域——子流域完整性进行巢湖流域生态功能分区。在综合分析巢湖流域生态环境基本特征的基础上,确定生态功能分区原则、依据、方法及命名,基于遥感与GIS在数据采集方面及多层面叠加功能的优势,通过遥感数据对研究区土地利用信息的提取以及利用DEM空间分析进行子流域划分等技术手段,探讨了遥感和GIS技术支持下的研究区子流域生态功能划分方法,形成了巢湖流域生态功能分区方案,将全流域分为5个生态功能区和12个生态功能亚区,并阐明了不同生态功能区的生态保护重点与经济社会发展约束。对于新调整行政区划的巢湖流域生态环境综合治理具有重要的现实意义,可为流域产业布局、生态防灾减灾、环境保护与建设规划等提供科学依据。     

Vertebral evolution and ontogenetic allometry: The developmental basis of extreme body shape divergence in microcephalic sea snakes

Snakes exhibit a diverse array of body shapes despite their characteristically simplified morphology. The most extreme shape changes along the precloacal axis are seen in fully aquatic sea snakes (Hydrophiinae): “microcephalic” sea snakes have tiny heads and dramatically reduced forebody girths that can be less than a third of the hindbody girth. This morphology has evolved repeatedly in sea snakes that specialize in hunting eels in burrows, but its developmental basis has not previously been examined. Here, we infer the developmental mechanisms underlying body shape changes in sea snakes by examining evolutionary patterns of changes in vertebral number and postnatal ontogenetic growth. Our results show that microcephalic species develop their characteristic shape via changes in both the embryonic and postnatal stages. Ontogenetic changes cause the hindbodies of microcephalic species to reach greater sizes relative to their forebodies in adulthood, suggesting heterochronic shifts that may be linked to homeotic effects (axial regionalization). However, microcephalic species also have greater numbers of vertebrae, especially in their forebodies, indicating that somitogenetic effects also contribute to evolutionary changes in body shape. Our findings highlight sea snakes as an excellent system for studying the development of segment number and regional identity in the snake precloacal axial skeleton.     

黄土高原生态分区及概况

黄土高原地域广阔,水土流失区域差异显著。为了有效治理水土流失,评估水土流失治理技术和模式及生态恢复建设工程的成效性,需要对黄土高原进行区域划分。依据自然条件、水土流失治理技术和模式的区域性特征及差异,基于国家基础地理信息系统数据的县级行政界,对其进行合并,进行生态分区的划分,并分别统计其气候、地形地貌、植被特征及水土流失现状,以期为黄土高原水土流失治理技术和模式的改良优化提供依据。主要结论如下:(1)黄土高原分为黄土高塬沟壑区,黄土丘陵沟壑区,沙地和农灌区,土石山区及河谷平原区。其中黄土高塬沟壑区和黄土丘陵沟壑区分别划分为两个副区。(2)黄土高原的气候、植被、水土流失具有明显的分区差异。降水和植被覆盖度自东南向西北递减,二者在空间分布上具有很好的一致性,降水量大的分区,植被覆盖度也高。在年际变化方面,丘陵沟壑区B2副区降水量呈增加趋势,其他分区呈减小趋势,变化均不显著。80年代以来,黄土高原和各生态分区的植被覆盖度均逐渐增加,黄土丘陵沟壑区的增加量最大。各分区的面平均气温均呈非显著增加趋势,90年代以来增温明显。(3)1970年以来,黄土高原侵蚀产沙强度减弱趋势显著,至2002—2015年,多年平均输沙模数在0.13—3924 t km~(-2) a~(-1)之间,侵蚀强度最大为中度侵蚀(2500—5000 t km~(-2) a~(-1)),但面积较小,主要分布于第二高塬沟壑区的泾河流域。