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51.
中国长臂猿的分布(英文) 总被引:5,自引:1,他引:4
中国南部分布着3种长臂猿,它们是白眉长臂猿(Hylobates hoolock)、白掌长臂猿(H.lar)和黑冠长臂猿(H.concolor)。黑冠长臂猿在我国境内有3个亚种:指名亚种(H.c.concolor),白颊亚种(H.c.leucogenys)和海南亚种(H.c.hainanus)。这些种类目前只分布在云南和广东的海南岛,但在五十年代初也生活在广西的西南部。这些地区是长臂猿属分布区的东北边界。 同它们在中南半岛的地理特征相一致,中国的3种长臂猿的分布区不相重迭,以两条大江为界。白眉长臂猿栖居在云南怒江以西,白掌长臂猿生活在怒江与澜沧江之间地带,黑冠长臂猿占据澜沧江以东。但是有一处,即黑冠长臂猿的云南保山瓦窑分布点例外,该地的标本收藏在动物研究所。 对于黑冠长臂猿海南亚种的文献记述存在不确切之处。现有较多的标本表明,海南亚种的雌性个体头冠部具有界限明显的黑色大斑块;成年雌性个体背毛呈浅棕灰色或较鲜亮的赭黄色;背中部毛较长,在40—75毫米之间。 我们所研究的标本收藏在以下单位:纽约美国自然历史博物馆,北京自然博物馆,芝加哥福地自然历史博物馆,复旦大学生物系,中国科学院动物研究所,广州华南濒危动物研究所,上海自然博物馆,上海动物园(活体),中山大学生物系。 相似文献
52.
G. Goldstein F. Rada L. Sternberg J. L. Burguera M. Burguera A. Orozco M. Montilla O. Zabala A. Azocar M. J. Canales A. Celis 《Oecologia》1989,78(2):176-183
Summary The gas exchange and water relations of the hemiparasite Pthirusa maritima and two its mangrove host species, Conocarpus erectus and Coccoloba uvifera, were studied in an intertidal zone of the Venezuelan coast. Carbon uptake and transpiration, leaf osmotic and total water potential, as well as nutrient content in the xylem sap and leaves of mistletoes and hosts were followed through the dry and wet season. In addition, carbon isotope ratios of leaf tissue were measured to further evaluate water use efficiency. Under similar light and humidity conditions, mistletoes had higher transpiration rates, lower leaf water potentials, and lower water use efficiencies than their hosts. Potassium content was much higher in mistletoes than in host leaves, but mineral nutrient content in the xylem sap of mistletoes was relatively low. The resistance of the liquid pathway from the soil to the leaf surface of mistletoes was larger than the total liquid flow resistance of host plants. Differences in the daily cycles of osmotic potential of the xylem sap also indicate the existence of a high resistance pathway along the vascular connection between the parasite pathway along the vascular connection between the parasite and its host. P. maritima mistletoes adjust to the different physiological characteristics of the host species which it parasitizes, thus ensuring an adequate water and carbon balance. 相似文献
53.
54.
Sulabha P Argade G Doyle Daves Jr Herman Van Halbeek Jack A Alhadeff 《Glycoconjugate journal》1989,6(1):45-56
The effects of treatments of the glycoprotein ribonuclease-B, the proteins ribonuclease-A and myoglobin, and the glyco-amino acid GlcNAc(1-N) Asn with alkalil alkaline sodium borohydride, and aqueous sodium borohydride were systematically studied as a function of the concentration of the reagents, the temperature, and the length of the treatment. High-field1H-NMR spectroscopy, chromatographic methods and amino-acid analysis were used to characterize products of the treatments of the various compounds. Our results indicate that mild alkaline borohydride treatment, as well as aqueous borohydride treatment alone, is capable of extensively degrading polypeptides and of partially releasing theN-linked glycans from ribonuclease-B. Initially, glycopeptides are produced, the peptide portion of which consists of several amino acids, which are further hydrolyzed to yield a mixture of glyco-asparagines and oligosaccharide-alditols in the ratio of 4:1. Strong alkaline borohydride treatment of ribonuclease-B is capable of completely releasing theN-linked carbohydrates as oligosaccharide-alditols.Abbreviation RNase
ribonuclease 相似文献
55.
Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus
because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species
and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with
human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to
these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques. 相似文献
56.
57.
Enhanced transfection efficiency and improved cell survival after electroporation of G2/M-synchronized cells and treatment with sodium butyrate. 总被引:10,自引:3,他引:7
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To achieve high transfection efficiency in human fibroblasts with good preservation of proliferative capacity we developed an electroporation procedure that combines two distinct modalities: use of recipient cells synchronized in the late G2/mitotic phase of the cell cycle and treatment of cells post-electroporation with 5 mM butyrate. This combination enabled reduction of plasmid DNA concentration and electroporation voltage, both associated with cytotoxicity, while greatly enhancing transfection efficiencies. Although the method was primarily developed for transient expression it was also found to improve stable expression. This procedure should have wide applicability, particularly in studies seeking to identify DNA sequences that lead to inhibition of DNA synthesis and proliferation in human fibroblasts and other cells refractory to transfection. 相似文献
58.
Competition between solution and cell surface receptors for ligand. Dissociation of hapten bound to surface antibody in the presence of solution antibody. 总被引:6,自引:5,他引:1
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B Goldstein R G Posner D C Torney J Erickson D Holowka B Baird 《Biophysical journal》1989,56(5):955-966
We present a joint theoretical and experimental study on the effects of competition for ligand between receptors in solution and receptors on cell surfaces. We focus on the following experiment. After ligand and cell surface receptors equilibrate, solution receptors are introduced, and the dissociation of surface bound ligand is monitored. We derive theoretical expressions for the dissociation rate and compare with experiment. In a standard dissociation experiment (no solution receptors present) dissociation may be slowed by rebinding, i.e., at high receptor densities a ligand that dissociates from one receptor may rebind to other receptors before separating from the cell. Our theory predicts that rebinding will be prevented when S much greater than N2Kon/(16 pi 2D a4), where S is the free receptor site concentration in solution, N the number of free surface receptor sites per cell, Kon the forward rate constant for ligand-receptor binding in solution, D the diffusion coefficient of the ligand, and a the cell radius. The predicted concentration of solution receptors needed to prevent rebinding is proportional to the square of the cell surface receptor density. The experimental system used in these studies consists of a monovalent ligand, 2,4-dinitrophenyl (DNP)-aminocaproyl-L-tyrosine (DCT), that reversibly binds to a monoclonal anti-DNP immunoglobulin E (IgE). This IgE is both a solution receptor and, when anchored to its high affinity Fc epsilon receptor on rat basophilic leukemia (RBL) cells, a surface receptor. For RBL cells with 6 x 10(5) binding sites per cell, our theory predicts that to prevent DCT rebinding to cell surface IgE during dissociation requires S much greater than 2,400 nM. We show that for S = 200-1,700 nM, the dissociation rate of DCT from surface IgE is substantially slower than from solution IgE where no rebinding occurs. Other predictions are also tested and shown to be consistent with experiment. 相似文献
59.
T W Martin D R Feldman K E Goldstein J R Wagner 《Biochemical and biophysical research communications》1989,165(1):319-326
Bovine pulmonary artery endothelial cells (BPAEC) were prelabeled with [3H]choline or [3H]myristic acid to selectively label endogenous phosphatidylcholine. BPAEC were stimulated with ATP and bradykinin (BK), and phospholipase D (PLD) activation was detected as a 4-fold increase in [3H]choline in cells prelabeled with [3H]choline or as a 2- to 3-fold increase in [3H]phosphatidylethanol in cells prelabeled with [3H]myristic acid and stimulated in the presence of ethanol. Pretreatment of BPAEC with 0.1 microM phorbol 12-myristate 13-acetate (PMA) for 22 hr completely inhibited agonist-induced PLD activation, whereas prostacyclin synthesis and [3H]phosphoinositide ([3H]PIns) hydrolysis were enhanced in pretreated cells. Long-term PMA treatment thus dissociates agonist-induced PLD activation from [3H]PIns hydrolysis, and agonist-induced prostacyclin synthesis is not dependent upon PLD activation. 相似文献
60.