DNA probes to identify members of the Anopheles farauti complex

DNA probes have been constructed to distinguish between the members of the Anopheles farauti complex of mosquitoes known as species numbers 1, 2 and 3. Partial genomic libraries of the three known species were exposed to labelled total genomic DNA from each species. Colonies showing differential hybridization were selected for further testing. These probes were found which allow identification of the three known species: probe pAf1 (160 bp fragment) hybridizes to DNA from An. farauti nos. 1 and 2; probe pAf2 (95 bp fragment) hybridizes to DNA from An. farauti no. 2 only; and probe pAf3 (1.3 kb fragment) hybridizes strongly to DNA from An. farauti no. 3, less to no. 1 and faintly to no. 2. Increasing the stringency of hybridization reduced the cross-hybridization of probes pAf1 and pAf3. Only radioactively labelled probes were tested. Males and females and individuals from diverse habitats and localities showed the same species/probe hybridization characteristics. This technique allows faster identification of the sibling species than previous methods, and has the added advantage that it allows air-dried and alcohol stored specimens to be identified.     

Plant community structure in relation to grazing and environmental changes along a north-south transect in the western Kalahari

Sixteen vegetation types were described from a north-south transect in the western Kalahari. Pronounced differences were found between communities on the nutrient poor red Kalahari sand, covering most of the area and those on fine soils and white calcareous sand. Syntaxa resulting from severe overgrazing by livestock were in most cases clearly distinguished from the less disturbed vegetation. The communities on red sand consisted mainly of shrub savanna dominated by perennial tufted grasses, whereas in the vegetation on calcareous material and on overgrazed land, forbs, dwarf shrubs and shrubs played a more important role. The major communities on red sand showed a clear geographical zonation roughly corresponding to the gradient in mean annual rainfall and its interannual variation. In the northern and central Kalahari these syntaxa were dominated by species of Sudano-Zambezian origin and in the southern Kalahari by species showing Karoo-Namib affinities.     

Differential heat shock gene expression in chick blastula

Summary The component areas of chick blastula show differential expression of heat shock genes. The area opaca (ao), marginal zone (mz) and central area (ca) components of the epiblast display distinct quantitative and minor qualitative differences in the heat-induced and heat-repressible proteins, but are clearly different from the primary hypoblast (endoderm) in their expression of a given stress protein (hsp) as a response to heat shock. The major proteins synthesized in the component areas of epiblast in response to heat shock include hsp 18, 24, 70 and 89 Kd. Two-dimensional electrophoresis shows that each of these proteins consists of multiple charged species. The hypoblast expresses only hsp 70 Kd at non-significant levels and shows marked inhibition in the level of synthesis of heat-shock-repressible proteins. Heat shock during the blastula stage results in an increase in the size of the blastoderm and disrupts normal embryonic development. The heat shock genes provide an important molecular marker, which attests to regional specification in the chick blastula.     

武陵山地区鱼类寄生杆咽属线虫两新种

本文报道在武陵山地区的白甲鱼［（Ｖａｒｉｃｏｒｋｉｎｕｓ（Ｏｎｙｃｈｏｓｔｏｍａ）ｓｉｍｕｓ（ＳａｕｖａｇｅｅｔＤａｂｒｙ）］和沪溪直口峻（ＲｅｃｔｏｒｉｓｌｕｘｉｅｎｓｉｓＷｕｅｔＹａｏ）中发现的两种杆咽属（Ｒｈａｂｄｏｃｈｏｎａ）线虫新种,定名为白甲鱼杆咽线虫,新种（ＲｈａｂｄＯｃｈｏｎａｏｎｙｒｋｏｓｔｏｍｉｓｐ．ｎｏｖ．）和短咽杆咽线虫,新种（ＲｈａｂｄＯｃｈｏｎａｂｒｅｖｉｃｈｏｎａｓｐ．ｎｏｖ．）,并对两新种进行了测量和详细的描述。     

Outgroup heteroduplex analysis using temperature gradient gel electrophoresis: high resolution, large scale, screening of DNA variation in the mitochondrial control region

The ability of DNA screening techniques such as Temperature Gradient Gel Electrophoresis (TGGE) and Heteroduplex Analysis to provide resolution approaching that provided by DNA sequencing for a fraction of the time, effort and expense point to them as the logical successor to allozyme electrophoresis for population genetics. Here we present a novel alternative to the standard TGGE/Heteroduplex Analysis protocol - Outgroup Heteroduplex Analysis (OHA). We assess this technique's sensitivity in comparison to previous screening approaches using a known hierarchy of sequence differences. Our data show that Outgroup Heteroduplex Analysis has greatly increased sensitivity for screening DNA variants from that of TGGE used alone and is easily applicable to large numbers of samples. Using this technique we can consistently detect differences of as small as one base change in a 433-base-pair fragment of Control Region mitochondrial DNA from Melomys cerbinipes (an Australian rodent). The approach should easily be extendable to nuclear loci and is not necessarily dependent on the use of a denaturing gradient When combined with a targeted sequencing effort, OHA provides a sensitive and simple means of obtaining allele/haplotype frequencies and their phylogenies for population and phylogeographic studies in molecular ecology.     

Middle Ordovician reefs of Norway

The Middle Ordovician reefs of Norway were the first to develop in the western part of the Balto-scandian epicontinental sea and are the earliest coral-stromatoporoid reefs so far reported in Europe. Small patch reefs in the Steinvika Limestone, Langesund-Skien district, consist mainly of algae, echinoderms, corals and stromatoporoids. Bryozoans, molluscs, arthropods and brachiopods are also present. The reefs developed on pelmatozoan-rich substrates and are organically zoned, consisting of a pioneer community of stemmed echinoderms and sheet algae, a high-diversity intermediate community dominated by fasciculate corals and a low diversity climax community of massive corals and stromatoporoids. These communities are interpreted as the seral stages of an autogenic ecological succession. Small patch reefs are also present in the laterally equivalent Mjøsa Limestone, Toten and Nes-Hamar districts. These are organically very similar to those in the Steinvika Limestone and developed in an identical way. A large complex, consisting of several reefs, is also present in the Mjøsa Limestone. Unlike the reefs elsewhere, which developed within shallow inshore areas, this complex developed at the outer edge of the inshore shelf. The outstanding feature of the complex is the main reef forming the offshore limit which is totally dominated by stromatoporoids and lacks a sequential development. This is due to the influence of the harsher environment at the shelf edge.     

新疆植被生产力与叶面积指数的变化及其对气候的响应

利用美国探路者卫星遥感资料AVHRR LAI和全球生态模式CASA给出的植被净初级生产力资料(NPP)对新疆地区1982~2000年的植被时空变化进行了定量分析,结果表明新疆地区的LAI和NPP的空间分布严格受水分的制约,与气温呈负相关,表现出干旱内陆地区植被受降水控制的地带特征。相对于20世纪80年代,90年代整个新疆出现了变暖的趋势,降水基本也呈现增加的趋势,在42°N以北地区暖湿转型尤其明显,与这种气候型相对应,植被出现了明显的增加趋势,NPP最大增幅可达45gCm-2a-1。但植被对气温和降水的年际变化响应不一样,降水主要是影响植被峰值的起落,而植被在总体演变趋势上却主要受气温控制,3个分区1984~2000年的气温明显上升,而降水变化趋势不明显,植被受气温控制出现了显著的上升趋势(P<0.01)。     

RCPs气候情景下珠江三角洲地区城市用地扩展的预测与模拟

随着社会经济的快速发展,中国城市规模和数量不断扩大,城市土地利用系统内部变化错综复杂.本研究以珠江三角洲地区城市群为例,研究了在自然环境条件和社会经济条件共同作用下城市化进程中城市用地动态变化的驱动机制,并设计了规划情景和RCPs气候情景,运用决策树元胞自动机模型对这几种情景下珠江三角洲地区城市用地的动态变化进行预测模拟.结果表明: 非农业人口和社会经济的增长对城市化过程起着决定性的推动作用,交通干线在整个城市化进程中始终起着重要的基础性作用,高程较高和坡度较大的区域制约了该地区的城市化进程.随着时间的推移,无论哪种情景,城市用地扩张的态势不变,但扩张速度到一定时间节点将会减缓,不同情景下减缓的时间点不同;规划情景、MESSAGE模式和AIM模式下的城市用地发展速度依次增加,但MESSAGE气候模式下的城镇发展较符合当前的城镇发展态势;城市用地扩张的区域主要集中在广州、东莞、佛山、珠海、深圳、湛江和潮汕等城市化相对较高的区域.