尖尾藻的染色质碱性蛋白研究

利用“先固定后抽提”的方法,从尖尾藻细胞中提取出染色质碱性蛋白。经ＳＤＳ－ＰＡＧＥ分析,结果显示此染色质碱性蛋白含有八个组分（记为１＇、１″、２ａ、２ｂ、３＇、３″、４＇、４″）,它们像小牛胸腺组蛋白一样形成两个分子量区域,即一为对应组蛋白Ｈ１的分子量区域,另一对应于核心组蛋白（即Ｈ２Ａ,Ｈ２Ｂ,Ｈ３,Ｈ４）的分子量区域;其与组蛋白各组分的具体对应关系大致为：对应于小牛胸腺组蛋白Ｈ１两亚带区域有两     

CONSPIRATORIAL WHISPERS AND CONSPICUOUS DISPLAYS: GAMES OF SIGNAL DETECTION

Recent models of signaling have assumed that the expenditure required to ensure detection of a display is negligible and have concentrated instead on the costs that may be necessary to maintain honesty. Such models predict that individuals who share the same interests are likely to communicate using “conspiratorial whispers,” signals that are cheap and inconspicuous. Here, I present a game-theoretical model of signal detection (in a noisy environment, in the presence of potential eavesdroppers), which demonstrates that the idea of conspiratorial whispers is far too simplistic. It is true that in “cooperative” signaling systems (where signalers attempt to elicit responses that are beneficial for receivers), signal cost is not required to maintain honesty. However, some level of expenditure is still needed to ensure that a signal is reliably detected. Moreover, there exists a conflict of interest between signalers and receivers over the division of this expenditure. To predict the stable level of display in such cases, one needs to know how this conflict of interest will be resolved. The model reveals that the outcome may range from a whisper to a conspicuous and costly (though still conspiratorial) display. The more closely related the receiver is to the signaler, the greater the level of signal exaggeration that is expected—the opposite prediction to that of honest signaling models.     

6种1变种猕猴桃植物染色体数目的研究

报道了猕猴桃属６种１变种细胞染色体数目,表明湖北猕猴桃、激光猕猴桃、黄毛猕猴桃为二倍体,２ｎ＝２ｘ＝５８;大花猕猴桃为四倍体,２ｎ＝４ｘ－１１６,绿果猕猴桃（美味猕猴桃的１个变种）为种倍体,染色体数目２ｎ＝４ｘ－１１６,以上均为首次报道。并再次证实ｘ＝２９应是本属染色体数目的基础,狗枣猕猴桃和阔叶猕猴桃二倍体类型２＝５８。     

异叶苣苔属(苦苣苔科)的核型研究

本文首次报道了中国特有异叶苣苔属的染色体数目及核型。该属所研究种类的染色体数目均为 2n＝18,染色体长度在2.0µm以上,在尖舌苣苔族所报道的染色体中显示出较原始的性状。尖舌苣苔 族的染色体基数可能是x=9。异叶苣苔属的间期核均为复杂型;前期染色体呈渐变型。核型从对称型 向不对称型的演化主要表现在近中部着丝粒,尤其是近端部着丝粒染色体比例的增大。毕节异叶苣苔 W．bljieensis和峨眉异叶苣苔W．tsiangiana var．wilsonii的核型分别为2n=2m＋8m＋8sm(1sat)和 2n=2m＋8m(1sat)＋8sm(2sat),较为对称。紫红异叶苣苔W．purpurascens和白花异叶苣苔W. tsiangiana var. tsiangiana的核型分别为2n=4m＋6sm＋8st(1sat)和2n=4m＋8sm(2sat)＋6st,比较 特化。河口异叶苣苔W．hekouensis的核型是2n=4m+10sm(1sat)+4st,处于二者之间。峨眉异叶苣 苔和原变种白花异叶苣苔的核型差异较大,在外部形态方面二者之间的性状变异也间断较大。本文建 议将该变种从白花异叶苣苔W．tsiangiana中移出自成一种,并和毕节异叶苣苔近缘。     

Blood cell induction in Xenopus animal cap explants: Effects of fibroblast growth factor, bone morphogenetic proteins, and activin

 Cultures of Xenopus blastula animal caps were used to explore the haematopoietic effects of three candidate inducers of mesoderm: basic fibroblast growth factor (bFGF), bone morphogenetic proteins (BMPs) and activin A. In response to either bFGF or activin A, explants expanded into egg-shaped structures, and beneath an outer layer of epidermis, a ventral mesodermal lining surrounded a fluid-filled cavity containing ”blood-like cells”. Immunocytochemistry identified some of these cells as early leukocytes, but erythrocytes were rare. BMP-2 or BMP-4 induced primitive erythrocytes as well as leukocytes, and a high concentration was required for these cells to differentiate in only a small proportion of explants. BMP-2 but not BMP-4 induced ventral mesoderm concomitantly. High concentrations of activin A dorsalized explants, which contained infrequent leukocytes, and an optimal combination of activin A and bFGF caused differentiation of muscle with few blood cells. By contrast, BMP-2 or BMP-4 plus activin A synergistically increased the numbers of both leukocytes and erythrocytes. Explants treated with BMPs plus activin contained a well organized cell mass in which yolk-rich cells mixed with blood cells and pigmented cells did not. BMP-2 plus bFGF also induced numerous leukocytes and fewer erythrocytes, but BMP-4 antagonized the leukopoietic effect of bFGF. The data suggest that the signalling pathways these three factors use to induce leukopoiesis overlap and that erythropoiesis may be activated when inducers are present in combination. Received: 3 August 1998 / Accepted: 7 October 1998     

Scintigraphic detection of xenografted tumors producing human basic fibroblast growth factor

A murine monoclonal antibody 3H3 recognizes the basic fibroblast growth factor (FGF) and inhibits the growth of human glioblastoma cells both in vitro and in vivo. We studied the potential of a scintigraphic technique using the 3H3 antibody to detect tumors that produce basic FGF.¹²⁵I- and¹¹¹In-labeled 3H3 bound to U87MG human glioblastoma cells in vitro. U87MG cells were inoculated subcutaneously into nude mice. After development of the tumor, radiolabeled 3H3 was injected into the subcutaneous space surrounding the tumor. A high level of radioactivity from 3H3 was retained at the tumor, whereas an irrelevant antibody cleared rapidly from the injected site. Radiolabeled 3H3 was not retained in tumors that did not produce basic FGF. Scintigraphic detection of tumors expressing basic FGF would be valuable for the therapeutic application of the antibody.     

Basic fibroblast growth factor in rat salivary glands

We studied the occurrence and localization of basic fibroblast growth factor (bFGF) in rat salivary glands using a specific monoclonal antibody. It was shown that the extract of rat salivary glands has a pronounced stimulatory activity on the growth of bovine capillary endothelial cells, which is blocked by the addition of an antibody against bFGF. The concentration of bFGF in the submandibular/sublingual gland, as determined by radioimmunoassay, was 80% that in the brain. Immunocytochemistry revealed bFGF-immunoreactivity localized primarily in the epithelial cells lining the striated ducts and excretory ducts of the parotid, sublingual and submandibular glands. In addition, intense bFGF-immunoreactivity was observed in the granular convoluted tubule of the submandibular gland, localized predominantly in the agranular pillar cells, which lay in small numbers among the majority of weakly immunostained cells containing many apical secretory granules. At the electron-microscopic level, the immunoreactive material was distributed diffusely in the cytoplasmic matrix and nuclei of all immunoreactive cells, whereas it was absent from all cytoplasmic organelles including the secretory granules. These results indicate that bFGF is localized in different cellular and subcellular compartments from those of other growth factors in the duct system of rat salivary glands.     

Antipredator behavior and the asset-protection principle

Many species of animals face the continual problem of balancingthe trade-off between reducing predation risks and maintainingor increasing their reproductive fitness. The terms of the trade-offare often asymmetric: each separate behavioral decision maylead to only a marginal increase in fitness, but may place theorganism's entire future reproduction in jeopardy. Consequently,the organism's reproductive value is an important componentof most antipredator decision problems. In this paper reproductivevalue is considered as an asset in need of protection. The "asset-protectionprinciple" states that the larger the current reproductive asset,the more important it becomes to protect it. Because reproductivevalue is usually age and condition dependent, optimal antipredatorbehavior also often depends on these variables. I use a uniformmodeling technique (dynamic programming) to address a varietyof issues related to antipredator behavior     

模块神经网络及其性能

提出一个不同于实现ｙ＝ｆ（ｘ）的ＢＰ网络的神经网络模型,给出了网络的结构及并行动力学方程,证明了其动力学的稳定性。通过学习算法的建立,证明网络能精确实现输入矢量对（ｘ,ｙ）映入成相联系的输出矢量ｚ,最重要的是网络能同时存诸依时变化的时序模式与静态模式。此外并给出动力学学习算法,证明此学习算法的收敛性,计算机仿真证实理论结果,最后讨论了某些可能的应用。     

Basic fibroblast growth factor can induce exclusively neural tissue in Triturus ectoderm explants

Ectoderm was isolated from early gastrulae of Triturus alpestris and induced with recombinant basic fibroblast growth factor (b-FGF). Neural tissue differentiated in about 38% of the explants which were induced by 2,5 g/ml FGF. These explants do not contain other tissues, or contain only small amounts of mesenchyme and melanophores which are probably derived from induced neural crest. It is therefore unlikely that these neural tissues are secondarily induced. The other explants contain predominantly blastema tissue, endothelium/ mesothelium, small amounts of skeletal muscle and, rarely, notochord besides neural tissues. The mitotic rate was enhanced in about 20% of the induced explants. Possible mechanisms for the unexpected neural-inducing activity of b-FGF in Triturus ectoderm are discussed.