Hemoglobin Kinetics of the Galapagos Rift Vent Tube Worm Riftia pachyptila Jones (Pogonophora; Vestimentifera)

Kinetics of the reactions of Riftia pachyptila hemoglobin with oxygen were followed spectrophotometrically by stopped-flow and laser flash photolysis techniques. The rate of oxygen dissociation increases eightfold over the range of 5 degrees to 20 degrees C (k = 2.2 sec(-1)at 10 degrees C). Oxygen recombination after flash photolysis was biphasic. The rates of both slow and fast phases of the reaction were independent of temperature from 0 degrees to 20 degrees C(k'fast = 7 x 10(6); k'slow = 1 x 16(6) liter mole (-1) sec(-1)). As the oxygen affinity is relatively temperature independent, analysis in terms of the two-state model of cooperativity requires that the conformational equilibrium constant L decrease by about 50-fold between 3 degrees and 15 degrees C.     

Dissociation of gp120 from HIV-1 virions induced by soluble CD4

The CD4 antigen is the high affinity cellular receptor for the human immunodeficiency virus type-1 (HIV-1). Binding of recombinant soluble CD4 (sCD4) or the purified V1 domain of sCD4 to the surface glycoprotein gp120 on virions resulted in rapid dissociation of gp120 from its complex with the transmembrane glycoprotein gp41. This may represent the initial stage in virus-cell and cell-cell fusion. Shedding of gp120 from virions induced by sCD4 may also contribute to the mechanism by which these soluble receptor molecules neutralize HIV-1.     

Abnormal hemoglobin studies in Taiwan aborigines

No abnormal hemoglobins were detected in a survey of blood samples from three of the largest aboriginal tribes of Taiwan. Samples from 655 individuals of the Ami, Paiwan, and Atayal tribes were examined by Smithies' method of vertical starch gel electrophoresis at pH 9.0. Only the A hemoglobins were found.     

V型小麦细胞质雄性不育“三系”及杂交种线粒体DNA的比较研究

以V型小麦细胞质雄性不育系及相应的保持系、恢复系以及其杂种F1为材料,用ISSR、SRAP、RAPD分子标记技术对它们的线粒体DNA进行了比较分析。结果如下:(1)153个SRAP引物组合中139个组合扩增出了多态性,9个组合扩增出不育系特有而保持系、恢复系、F1均缺失的片段,3个组合扩增出不育系特异缺失的片段。(2)92个ISSR引物中45个扩增出了多态性,筛选到了6个不育系特有而保持系、恢复系及杂种F1均缺失的片段。(3)288个RAPD引物中281个扩增出了多态性,4个引物扩增出不育系特有的片段,3个引物扩增出不育系特异缺失的片段。在对线粒体DNA进行分析时,SRAP比ISSR多态性好,比RAPD稳定性好。     

豆油脱臭馏出物中α-VE的超临界CO2萃取研究

以甲酯化豆油脱臭馏出物为原料 ,利用超临界 CO2 萃取技术浓缩 α- VE,探讨萃取条件对 α- VE和豆油脱臭馏出物中油脂萃取效果的影响。结果表明 ,萃取压力和萃取温度对 α- VE和脂肪酸在超临界二氧化碳中的萃取效果有非常显著的影响 ,而二氧化碳流量对萃取效果影响较小。在萃取温度 30 8K,萃取压力 18MPa,二氧化碳流量 6～ 12 L/ m in条件下 ,可以获得较高的萃取得率和 α- VE含量。     

Directed assembly of one-dimensional nanostructures into functional networks

One-dimensional nanostructures, such as nanowires and nanotubes, represent the smallest dimension for efficient transport of electrons and excitons and thus are ideal building blocks for hierarchical assembly of functional nanoscale electronic and photonic structures. We report an approach for the hierarchical assembly of one-dimensional nanostructures into well-defined functional networks. We show that nanowires can be assembled into parallel arrays with control of the average separation and, by combining fluidic alignment with surface-patterning techniques, that it is also possible to control periodicity. In addition, complex crossed nanowire arrays can be prepared with layer-by-layer assembly with different flow directions for sequential steps. Transport studies show that the crossed nanowire arrays form electrically conducting networks, with individually addressable device function at each cross point.     

Climate Change During the Last Deglaciation in Antarctica

Greenland ice core records provide clear evidence of rapid changes in climate in a variety of climate indicators. In this work, rapid climate change events in the Northern and Southern hemispheres are compared on the basis of an examination of changes in atmospheric circulation developed from two ice cores. High-resolution glaciochemical series, covering the period 10,000 to 16,000 years ago, from a central Greenland ice core and a new site in east Antarctica display similar variability. These findings suggest that rapid climate change events occur more frequently in Antarctica than previously demonstrated.     

Cell recognition during neuronal development

Insect embryos, with their relatively simple nervous systems, provide a model system with which to study the cellular and molecular mechanisms underlying cell recognition during neuronal development. Such an approach can take advantage of the accessible cells of the grasshopper embryo and the accessible genes of Drosophila. The growth cones of identified neurons express selective affinities for specific axonal surfaces; such specificities give rise to the stereotyped patterns of selective fasciculation common to both species. These and other results suggest that early in development cell lineage and cell interactions lead to the differential expression of cell recognition molecules on the surfaces of small subsets of embryonic neurons whose axons selectively fasciculate with one another. Monoclonal antibodies reveal surface molecules in the Drosophila embryo whose expression correlates with this prediction. It should now be possible to isolate the genes encoding these potential cell recognition molecules and to test their function through the use of molecular genetic approaches in Drosophila.