Comparative Analysis of a Mitochondrial DNA Control Region Fragment Amplified from Three Adriatic Flatfish Species and Molecular Phylogenesis of Pleuronectiformes

The 5′-end of the mitochondrial control region of three Pleuronectiformes from the Adriatic Sea, Platichthys flesus italicus (Adriatic flounder), Solea vulgaris (common sole), and Solea kleini (Klein's sole), was sequenced and compared with that of six other flatfish species from the families Pleuronectidae and Bothidae. The sequence structures of all flatfishes appear very similar and consist of alternate short segments with low, medium, and high rates of nucleotide substitution. Four conserved 19-bp repeats occur at the beginning of the European and Adriatic flounder sequences. The common occurrence of tandem arrays in fish control regions could be related to a stable secondary structure. Molecular phylogenetic relationships among Pleuronectiformes agree well with previous morphologic data at all taxonomic levels. Molecular analyses could therefore contribute to resolving phylogenetic and taxonomic debates within the Pleuronectiformes. Received December 1, 1997; accepted June 30, 1998.     

Population dynamics of three Neotropical small mammals: Time series models and the role of delayed density-dependence in population irruptions

It is widely believed that only precipitation levels (through increased primary production) determine irruptions of small mammals in semi-arid areas of western South America. Nevertheless, density-dependent factors may also drive population fluctuations. To test statistically these putative effects we analysed 11 years of population records on three sympatric species of small mammals at two different habitat types in north central Chile. We applied the classical diagnostic tools of time series analysis (the autocorrelation function: ACF) to the observed time series of three neotropical small mammals. We also used simple linear autoregressive time series models to reconstruct the endogenous dynamics of these populations. The analysis strongly suggests that population fluctuations of the three species have an important density-dependent component, with the most irruptive species (Phyllotis darwini, Waterhouse 1837) displaying stronger second order population feedbacks than the other two (Akodon olivaceus, Waterhouse 1837 and Thylamys elegans, Waterhouse 1839). The latter two species showed direct density-dependent feedbacks. We hypothesize that the frequent population outbreaks of P. darwini (and perhaps of other species) in semi-arid regions of western South America, may be the result of population-level (direct density- dependence) and community-level processes (delayed density-dependence), interacting with exogenous perturbations (rainfall and associated primary production).     

芜湖地区青少年儿童皮下脂肪及身体围度发育规律初探

分析了安徽省芜湖地区1217名城乡在校中小学生四项皮褶厚度及四项身体围度随年龄变化的规律,尤其是青春期的变化;以及营养、气候等环境因素对儿童青少年身体发育的影响。结果表明：在即将进入青春发育期时,男性四肢部皮下脂肪迅速减少;女性皮下脂肪在青春期迅速增厚;身体围度则随年龄增长而增加,在青春后期,围度保持在一定水平。     

In Vitro Divisions of Unfertilized Central Cells and Other Embryo Sac Cells in Nicotiana tabacum var macrophylla

The embryo sacs and female cells could be isolated from the unfertilized ovules of Nicotiana tabacum L. var. macrophylla which were treated in a solution containing 1.5 % cellulase R- 1O, 1% macerozyme R-10, 10% mannitol, 10 mmol/L CaCI:, pH 5.8 for 3 h followed by given slight pressure with a micropipette. The central cells could be kept viable for 10 h and the egg cells for 3 h in 10% mannital. Sometimes, the in situ fusion products of egg cell and synergid protoplasts could be obtained and kept viable for at least 5 h. The high concentration (20 mg/L) of 2, 4-D was used in enzyme solution to induce the division of the unfertilized central cells and other megagametophytic cells in subsequent culture. Treatment of 2,4-D together with enzymatic maceration of ovules was proved to be better than its direct treatment of isolated embryo sac or its component cells. Isolated embryo sacs were cultured in microchambers (Millicell-CM PICM 012 50 MILLIPORE) feeded with divided mesophyll protoplasts of Nicotiana rustica L. The medium was KMSp medium supple- mented with 1% glucose, 0.1 mol/L mannitol, 0.1 mol/L sorbitol, 0.25 mol/L sucrose, 1 mg/L BA, 6% to 10% coconut water, and 0.15% low gelling agarose. Division of central cells, antipodal cells and the in situ fusion products of egg cell and synergid protoplasts were induced. The unfertilized central cell was for the first time to be induced in vitro to develop into small cell clusters.     

东北水生植物区系与周缘地区水生植物区系关系的分析

本文在野外采集、查阅标本和文献考证的基础上,对东北地区水生植物区系与周缘地区水生植物区系的关系进行了初步分析。由于日本在地史起源上曾与大陆相连,且现代气候环境与东北地区的相似,故两者间水生植物的相似性系数最高O在更新世前古嫩辽河与结雅河相连通,使东北与远东地区间的水生植物得以相互交流,同时两区还保存有一些第三纪植物于遗种类,但因远东地区缺少东北暖温带气候,故一些东北产的暖温带种类未能分布该区,使其与东北水生植物种类相似性系数位于第二位。印度次大陆、澳大利亚、东南亚和非洲因与东北地区位于不同的气候带中,故水生植物种类相似性系数较低。在国内各地区中,以华北地区与东北地区水生植物的相似性系数最高,因两者过去同属古黄河水系,近代又接壤;相反,以与华南、台湾和海南岛的水生植物种类相似性系数最低。因相互间即存地理隔离,又无水系相通。     

Fossil wood charcoal assemblages from Elands Bay Cave, South Africa: implications for Late Quaternary vegetation and climates in the winter-rainfall fynbos biome

Aim The aim of this paper is to analyse fossil charcoal deposits, largely identified to the species level and spanning a sequence from the late Holocene to < 40,000 BP , in order to reconstruct Late Quaternary vegetation and climatic patterns in the western (winter-rainfall) fynbos biome of South Africa. Location The charcoals were excavated from the Elands Bay Cave (32°19S, 18°20E) on the semiarid (200–250 mmyr^?1), winter-rainfall coastline of the western fynbos biome. Methods Patterns in the charcoal data set over time were sought by manual sorting of the charcoal×sample matrix, as well as by subjecting the data to multivariate analysis. Palaeoclimatic reconstruction was attempted by comparing the climatic controls on contemporary vegetation communities that resembled the fossil assemblages. Charcoal diversity was modelled using sample age and number of charcoal fragments as explanatory variables. Results The fossil assemblages ranged from xeric communities (similar to those presently occurring at the site) during the Holocene, to more mesic thicket and fynbos vegetation in the terminal Pleistocene, to Afromontane forest and riverine woodland communities after about 18,000 BP . Diversity of the charcoal samples increased monotonically with increasing sample age. Main conclusions The results suggest that, unlike the eastern fynbos biome, which is under fundamentally different climatic controls, soil moisture conditions in the western part of the biome were higher in the Last Glacial than during the Holocene. This scenario may help to explain the higher regional richness and associated diversification in the western than eastern part of the biome.     

Effects of central administration of lead, cadmium and other divalent cations on body temperature in mice

The intracerebroventricular administration of lead or cadmium to mice produced a marked decrease in body temperature. The maximum decreases in body temperature produced by the central administration of the heavy metals (1.97±0.3°C for lead and 2.87±0.6°C for cadmium) were similar to those obtained after acute peripheral administration of these compounds. The decreases in body temperature obtained after central administration of calcium, magnesium or zinc were significantly smaller than those produced by the heavy metals. The results indicate that the central nervous system is implicated in the hypothermia induced by these divalent cations and suggest that the alteration of membrane ionic permeability by these substances at hypothalamic sites may be related to the control of body temperature.     

滇西横断山地区云南蝗属一新种（直翅目：瘤锥蝗科）

本文记述滇西横断山地区云南蝗属１新种,即白边云南蝗Ｙｕｎｎａｎｉｔｅｓａｌｂｏｍａｒｇｉｎａ,ｓｐ．ｎｏｖ,模式标本保存于陕西师范大学动物研究所。     

草鱼(Ctenopharyngodon idellus)线粒体DNA控制区及其两侧tRNA基因的克隆与结构分析

动物线粒体ＤＮＡ控制区是线粒体基因组复制与基因表达的最主要的调控区．采用杂交和测序的方法对草鱼线粒体ＤＮＡ控制区进行定位、克隆并测定了控制区及其旁侧的ｔＲＮＡＰｈｅ、ｒＲＮＡＰｒｏ和ｒＲＮＡＴｈｒ三个基因的序列,与多种脊椎动物的相应序列进行了比较,并进行了结构分析．草鱼线粒体控制区全长９２７ｂｐ,含有与酵母和爪蟾线粒体启动子相似的序列,其ＣＳＢⅠ、ＣＳＢⅡ和ＣＳＢⅢ序列与其他几种动物的ＣＳＢ比较相当保守,ＴＡＳ与其回文基序可形成稳定的茎环结构,成为Ｈ－链复制的终止信号．草鱼线粒体ｔＲＮＡＰｈｅ、ｔＲＮＡＰｒｏ和ｔＲＮＡＴｈｒ可折叠成三叶草形二级结构,其基因具有许多不同于细胞质ｔＲＮＡ基因的结构特点,可能反映了线粒体ｔＲＮＡ与线粒体核糖体具有不寻常的作用方式