ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE : II. The Giant Ameba Pelomyxa carolinensis

Dividing nuclei from the giant ameba Pelomyxa carolinensis were fixed in osmium tetroxide solutions buffered with veronal acetate to pH 8.0. If divalent cations (0.002 M calcium, magnesium, or strontium as chlorides) were added to the fixation solution, fibrils that are 14 mµ in diameter and have a dense cortex are observed in the spindle. If the divalent ions were omitted, oriented particles of smaller size are present and fibrils are not obvious. The stages of mitosis were observed and spindle components compared. Fibrils fixed in the presence of calcium ions are not so well defined in early metaphase as later, but otherwise have the same diameter in the late metaphase, anaphase, and early telophase. Fibrils are surrounded by clouds of fine material except in early telophase, when they are formed into tight bundles lying in the cytoplasm unattached to nuclei. Metaphase and anaphase fibrils fixed without calcium ions are less well defined and are not observably different from each other. The observations are consistent with the concept that spindle fibrils are composed of polymerized, oriented protein molecules that are in equilibrium with and bathed in non-oriented molecules of the same protein. Partially formed spindle fibrils and ribosome-like particles were observed in the mixoplasm when the nuclear envelope had only small discontinuities. Remnants of the envelope are visible throughout division and are probably incorporated into the new envelope in the telophase. Ribosome-like particles are numerous in the metaphase and anaphase spindle but are not seen in the telophase nucleus, once the envelope is reestablished, or in the interphase nucleus.     

广西金钟山鸟类保护区鸟类多样性初步研究

本文共记录到金钟山鸟类274种,分别隶属于18目57科,其中陆生鸟类251种,水鸟23种;以留鸟为主,共157种;候鸟、旅鸟分别为104种、13种;东洋种为优势类群,共有171种,古北种和广布种分别为4种、27种。这些鸟类中有国家重点保护鸟类39种,中国特有种鸟类3种,列入世界自然保护联盟红皮书名录中的鸟类5种,列入中国濒危动物红皮书名录中的鸟类20种,列入CITES附录中的鸟类34种。本文还对金钟山鸟类保护区的5种不同生境类型的鸟类种类组成作了比较,结果表明灌丛＋农田的鸟种多样性指数最高,为3．04;水域的鸟种多样性指数最低,为2．14。     

Studies on the morphology of the gills and gill arches with reference to the blood supply in Notopterus motopterus and Colisa fasciatus.

The morphology of the gills, with their blood supply have been described in Notopterus notopterus and Colisa fasciatus in some detail. Gills are curved and perforated on the dorsolateral and ventrolateral wall of the pharynx. The gills consist of 2 rows of filaments which are stacked one above the other to form a space. The gill filaments are smaller on both the ends and larger in middle. The gill filaments are of pink colour as they are supplied with blood. Gill rakers are large in size in Notopterus notopterus while they are small in Colisa fasciatus. 3 pairs of basibranchials are present in Notopterus notopterus which are covered by median membranous bony plate while 2 basibranchials are present in Colisa fasciatus. 3 pairs of hypobranchials are present in both fishes. 5 pairs of ceratobranchials are present in which Vth ceratobranchial bears teeth. 4 pairs of epibranchials are present. 3 pairs of pharyngobranchials are present in which the tip of the IVth pharyngobranchial bears minute teeth in Notopterus notopterus while in Colisa fasciatus IInd and IIIrd pharyngobranchial bear minute ones. One afferent branchial vessel is present in Notopterus notopterus and Colisa fasciatus in each gill like in other teleostean fishes. One efferent branchial vessel is present in each gill of Notopterus notopterus while in Colisa fasciatus 2 efferent are represented in each gill.     

新疆蝗总科区系研究

新疆现有蝗虫１５７种,它们分别隶属于８科６２属。在１５７种蝗虫中,古北种占绝对优势,有１２０种,其次为特有种,有３５种,广布种甚少,仅２种。在古北种中,中亚种最多,其次为泛古北种,而欧洲西伯利亚种、地中海种和东北种均很少。在８个科中,泛古北种在网翅蝗科中占优势,中亚种在班翅蝗科中占优势,斑腿蝗科在蝗总科中是相当大的一个科,在我国也占有很大优势,但在新疆其属种数量却很少。     

Hydrogen bonding in DNA base complexes.

Experimental intermolecular frequencies in the DNA base complexes 1-methylthymine (1-MT) and cytosine monohydrate (CMH) are analyzed in terms of simple analytic interatomic potentials. Calculations with two different values for the constants of the nonbonded interactions are considered, and the hydrogen bond potentials are determined for each of these models. The observed frequencies in 1-MT are reasonably well described, although corresponding potentials are very different in the two models. The observed frequencies in CMH are less well described, although corresponding hydrogen bond potentials are similar in the two models. Hydration interactions are found to be important in CMH and the role of the water molecule is discussed. Possible reasons for the shortcomings of this simple analysis are considered.     

Cotton embryogenesis: The sperm

Summary The sperm of cotton were observed in the pollen tube in the style. They are true cells but relatively simple in organization. The nuclei are small and each contains a single, very small nucleolus. Nuclear pores are common and heterochromatin lines the nuclear membrane. The plastids and mitochondria are so reduced in internal structure that it is impossible to separately identify them. The suggestion is put forward that only mitochondria are present in the sperm. Dictyosomes are few but appear to be producing large numbers of vesicles. Single membrane vesicles of a large range of sizes are common. ER is scarce but polysomes are numerous.     

潮汕地区农药植物资源初探

潮汕地区农药植物资源十分丰富。初步调查统计共有 88科 2 39种 ,其中蕨类植物 4种 ,裸子植物 6种 ,被子植物2 2 9种 ,这些农药植物均具有杀虫作用。本文对潮汕地区农药植物的研究和合理开发利用提出了若干建议     

江西木兰科植物的初步整理

通过野外采集及标本的整理鉴定, 确认江西产木兰科植物7 属22 种1 亚种, 其中3 种为江西特有种, 5 种为江西地理新分布。对各分类群进行了分类检索, 记载了其地理分布, 并列出凭证标本。     

深圳塘朗山郊野公园的植物资源

广东深圳塘朗山郊野公园共有野生维管植物144科423属611种,分别占广东省维管植物280科1589属5737种的51.4%、26.7%和10.65%;其中蕨类省植物21科29属33种,裸子植物3科3属4种,被子植物120科391属574种,被子植物占绝对优势。国家重点保护野生植物共计7科7属7种,占广东省国家重点保护野生植物的10.9%;珍稀濒危植物有4科5属5种,占广东省珍稀濒危植物67种的7%。公园中经济植物可分为12类,分别是药用植物321种,用材树种65种,观赏植物60种,纤维植物41种,野生水果33种,油脂植物38种,饲料植物42种,鞣料植物42种,野菜植物25种,农药植物27种,芳香植物26种,淀粉植物23种,保健植物19种,染料植物13种,有毒植物10种,蜜源植物5种。     

东北地区蒙古栎群落区系成分

根据吴征镒、王荷生区系分析方法, 分析了东北地区蒙古栎群落中２６１ 种维管植物的区系成分, 其中温带成分占４７－４７ ％ , 东亚成分占４２－０２ ％ , 中国特有成分占１０－５１ ％ （ 世界分布不统计在内） 。并分析了种所在属的分布区类型, 温带分布属占９０－３％ 。还分别分析了蒙古栎群落的乔木层、灌木层、草本层以及层间植物的区系成分。     

浙江磐安种子植物区系的特征分析

磐安约有野生种子植物 1 44科 ,62 7属 ,1 2 98种 (包括种以下分类单位 )。其中世界成分的属 67个 ,占总属数的 1 0 .69% ,热带属 2 2 7个 ,占 36.2 0 % ,温带属 32 1个 ,占 5 1 .2 0 % ,中国特有属 1 2个 ,占 1 .91 %。磐安气候温暖湿润 ,植物种类丰富 ,古老、孑遗、珍稀植物多 ,单种属和少种属占有较大比重 ;优势科、优势属明显 ,优势科 34个 ,共含有 393属 ,776种 ,分别占总属数总种属的 62 .7% ,70 .3% ,优势属 1 0个 ,共含有 1 44种 ,分别占总属数总种数的 1 .6% ,1 1 .1 % ,其中樟科、壳斗科等是该区系的表征科 ;植物分布类型多样 ,地理成分复杂 ,温带成分和热带成分占优势 ,是亚热带分布的北缘 ,与世界各地有广泛的联系     

沙冬青冬季叶绿体的超微结构特征

沙冬青在冬季的叶肉细胞中有丰富的叶绿体,经常聚集在一起,相互重叠,相互嵌合,有的还相互融合。大部分叶绿体为凸透镜形,多余叶绿体主要为V形、蝶形、连婴形和哑铃形。它们的被膜不光滑,常凹凸不平,甚至出现突起和内陷。类囊体十分发达,质体小球很多,但淀粉粒缺乏。大部分叶绿体形态结构正常,有的还在出芽和分裂。少数叶绿体与此不同,它们已经衰老,其中一些正在解体或已经解体。     

桂西北典型喀斯特区生态服务价值的环境响应及其空间尺度特征

Study on ecosystem service values (ESVs) is the bridge of understanding ecosystem and economic decision-making. To investigate the response of ESVs to ambient environment and their spatial scales is an urgent work in the process of ecological restoration and sustainable development in southwest China. Based on the previous research results, the remote images, and weather data of 31 years (1975-2005), the response of ESVs to ambient environment and their spatial scales in a typical karst area of northwest Guangxi, China were evaluated with the method of empirical mode decomposition (EMD) in this paper. The results showed that ESVs had obvious variations with changes in elevation, rocky types and soil types, and had corresponding characteristics of spatial scales. The ESVs in middle and low elevation areas were higher, but they decreased due to human activities such as deforestation. The ESVs in peak-cluster depression areas were lower, and they would increase as influenced by policies such as returning farmland to forestland. The ESVs were influenced by rocky types, showing lower values but an increasing trend in the typical karst regions while higher values but a decreasing trend in non-karst regions. The average ESVs in the west part of the study region, which is not only the main nature reserve for rare wildlife species in Guangxi, but also one of the best preserved natural vegetation regions in China, were more than 15,000 RMB Yuan ha-1,. Comparatively, the ESVs were less than 10,000 Yuan ha-1 in the middle part of the region attributed to low vegetation coverage, serious peak-cluster depression and karst rocky desertification. After about 20 years, that is from 1985 to 2005, the ecosystem conditions had been improved and the ESVs had increased in the middle and eastern part of this study region. On the contrary, in most western part, which was dominated by subtropical evergreen broad-leaved forest, they had been worsened, and the balance values of ESVs were negative. As for the relationships of ESVs with rocky types and soil types, lime soil and red soil were the two main soil types that contributed to ESVs (The total contribution was above 60%, and it is 63.77%,64.37%,64.56%,64.91% respectively in the four years of 1985, 1990, 2000 and 2005.). The variance contribution of intrinsic mode function (IMF) and trend (R) showed that there were obvious special sales for ESVs in this study area, and the main spatial scales were about 2.7 km, 5.5 km, and 11.6 km. The variance contribution ratio was 12.29%, 11.26%, 11.49% respectively, and the trend (R) was high (17.74%). In conclusion, this study indicated that ecosystem conditions in the typical karst area were improved owing to the application of rocky desertification control policies, such as ecological migration and returning farmland to forestland. Besides, the main spatial scales of ESVs in the study area were the interactions of terrain, physiognomy, land use / land cover and human activities.     

Compatibility and the genesis of residual stress by volumetric growth

The equations of compatibility which are pertinant for growth strain fields are collected and examples are given in simply-connected and multiply-connected regions. Compatibility conditions for infinitesimal strains are well known and the possibilities of Volterra dislocations in multiply-connected regions are enumerated. For finite growth strains in a multiply-connected regions, each case must be examined individually and no generalizations in terms of Volterra dislocations are available. Any incompatible growth strains give rise to residual stresses which are known to occur in many tissues such as the heart, arterial wall, and solid tumors.     

云南小孢发属地衣的分类

报道了云南小孢发属地衣１３种,其中中国新记录种６个,它们是：喜马拉雅小孢发,尼泊尔小孢发,光滑小孢发,光亮小孢发,多叉小孢发,波氏小孢发,另外７种的形态及分布也在文中进行了讨论。     

π–π Interactions in Structural Stability: Role in RNA Binding Proteins

RNA binding proteins play significant roles in many bio-macromolecular systems. Aromatic amino acid residues are vital for several biological functions. In the present work, the influences of π–π interactions in RNA binding proteins are analyzed. There are a total of 3,396 π-residues in RNA binding proteins out of which 1,547, 1,241, and 608 are phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), respectively. Among these 945, 634, and 356 Phe, Tyr, and Trp residues, respectively, are involved in π–π interactions. The observations indicate that majority of the aromatic residues in RNA binding proteins are involved in π–π interactions. Side chain–side chain π–π interactions are the predominant type of interactions in RNA binding proteins. These π–π interactions stabilize the core regions within RNA binding proteins. π–π interacting residues are evolutionary conserved. Residue-wise analysis indicates that π–π interacting residues have higher long-range contacts and hence they are important in the global conformational stability of these proteins.     

Wood, bark and stem anatomy of New World species of Gnetum

Quantitative and qualitative data are presented for 11 collections of six species. The wide range of character states for the species is presented in the form of a key to emphasize their potential systematic correlations. Distinctive among these are phcllem characteristics. Fibre-tracheids are newly reported for lianoid Gnetum species. Cells previously thought to be like companion cells in secondary phloem are shown to be uniseriate rays, counterparts to uniseriate xylem rays. Laticifers are abundant in most of the species, and are newly described for secondary tissues of Gnetum. Presence of tyloses in laticifers of two species is apparently a new report for vascular plants. Tori are present in two New World Gnetum species, adding to the report in African species. Perforation plates are simple except near or in primary xylem, where they are simple or foraminate. Torus presence and foraminate perforation plate presence are features more reminiscent of Ephedra and other gymnosperms than of angiosperms. The bark of Gnetum is also very similar to that of Ephedra.