Transport of 5-hydroxytryptamine by dense granules from porcine platelets

A method is described for the isolation of a homogeneous preparation of dense granules from procine platelets. The purified dense granule fraction contained approximately 400 nmol of 5-hydroxytryptamine/mg of protein and appeared to be homogeneous when examined by electron microscopy. Isolated dense granules transport exogenously added 5-hydroxytryptamine via two mechanisms: 1) a carrier-mediated process predominating at low substrate concentrations and 2) a diffusion-controlled process predominating at high substrate concentrations. Temperature studies revealed an apparent energy of activation of 14.9 kcal/mol for the carrier-mediated transport. Kinetic data yielded a Km of 3.3 micron and a Vmax of 0.79 nmol/min/mg of protein for the mediated transport process. Steady state uptake was sensitive to changes in medium osmotic pressure and a decline in uptake below 300 mosM was correlated with release of endogenous 5-hydroxytryptamine. The transport was inhibited by a number of structural analogs of 5-hydroxytryptamine. These results demonstrate the existence of a carrier-mediated transport system for 5-hydroxytryptamine in the membranes of the platelet dense granules.     

Lipases in the storage tissues of peanut and other oil seeds during germination

The castor-bean endosperm-the best-studied material of reserve lipid hydrolysis in seed germination-was previously shown to have an acid lipase and an alkaline lipase having reciprocal patterns of development during germination. We studied oil seeds from 7 species, namely castor bean (Ricinus communis L.), peanut (Arachis hypogaea L.), sunflower (Helianthus annus L.), cucumber (Cucumis sativus L.), cotton (Gossypisum hirsutum L.), corn (Zea mays. L.) and tomato (Lycopersicon esculentum Mill.). The storage tissues of all these oil seeds except castor bean contained only alkaline lipase activity which increased drastically during germination. The pattern of acid and alkaline lipases in castor bean does not seem to be common in other oil seeds. The alkaline lipase of peanut cotyledons was chosen for further study. On sucrose gradient centrifugation of cotyledon homogenate from 3-d-old seedlings, about 60% of the activity of the enzyme was found to be associated with the glyoxysomes, 15% with the mitochondria, and 25% with a membrane fraction at a density of 1.12 g cm^-3. The glyoxysomal lipase was associated with the organelle membrane, and hydrolyzed only monoglyceride whereas the mitochondrial and membrane-fraction enzymes degraded mono-, di- and triglycerides equally well. Thus, although the lipase in the glyoxysomes had the highest activity, it had to cooperate with lipases in other cellular compartments for the complete hydrolysis of reserve triglycerides.     

Intracellular recording of cerebral cortical actions of prostaglandin F2α (PGF2α)

Our reported data on the cortical inhibitory actions of prostaglandin F_2α (PGF_2α) and the diversity of data in the literature on cerebral PG actions are examined here in the light of intracellular recording which provides the requisite membrane data for the first time. Thus, 1) intracellular recording from the cat cerebral cortex is obtained for the actions of PGF_2α and for norepinephrine (NE) and serotonin (5HT). 2) The parallel changes in firing and polarization and the simultaneous transmembrane conductance changes are qualitatively identical for PGF_2α, NE and 5HT. 3) The reduction in firing accompanied by hyperpolarization indicates that PGF_2α, NE and 5HT all inhibit these cells. 4) The ionic species responsible for this inhibition is such that it increased the transmembrane resistance, and this was true for all three. 5) The changes in membrane parameters, identical in direction for PGF_2α and NE, but stronger for the latter, constitute conditions that can lead to competitive inhibition and therefore conote, presumably, actions at the same or related receptors. Such competition with evoked cortical field potentials is shown in the preceding paper.     

实验室内从幼年群体中培养出家白蚁短翅补充型

白蚁是多形态昆虫,一般每一家族可分为两大类型:生殖类型(繁殖蚁)和非生殖类型(不育蚁)。在两大类型中,一般又可分化为若干品级;非生殖类型中有工蚁和兵蚁等品级。对品级分化、生成及调节,近年来已做了很多工作。总的说来,白蚁品级分化不能单用遗传来解释。因为新孵化的幼蚁(若蚁)可以分化为各个品级的成员。多种因素,例如外激素及激素(内分泌)在品级分化上起到重要作用。     

Evidence for two conformational forms of monhistone protein BA which differ in their affinity for DNA

Nonhistone protein BA_free was purified from the 0.075 M NaCl/0.025 M $\text{EDTA}\text{pH}$ 8 extract of whole rat liver nuclei while protein BA_bound was isolated from the 0.05 M Na₂HPO₄/8 M urea/1% β-mercaptoethanol/pH 7.6 extract of dehistonized rat liver chromatin. Chromatin associated protein BA_bound was able to bind 60% of the [³H] DNA in a nitrocellulose filter binding assay while nucleoplasmic protein BA_free showed essentially no DNA binding activity. Circular dichroism analysis of the two forms of protein BA revealed substantial differences in their conformations. Protein BA_free was found to have an α-helix content of 41% while protein BA_bound displayed a spectrum more typical of unordered or β-turn structures.     

龙牙百合3个地方品种的形态特征及核型分析

采用经典测量和染色体常规压片法,对龙牙百合（Lilium brownii var.viridulum Baker）3个地方品种的形态特征及核型进行研究。植株形态分析结果显示：‘江西’龙牙的株高、开花口径、种球重量和周长、中外层鳞片重量和长度以及鳞片扦插产生小鳞茎数等指标均显著大于‘大叶’龙牙和‘平头’龙牙;‘大叶’龙牙的叶片最长,均值为14.54 cm。花粉、叶表皮气孔及鳞片淀粉粒的微形态特征分析结果显示：‘江西’龙牙的花粉粒径最大,均值达111.76 μm;‘平头’龙牙的叶表皮气孔最长,气孔密度也最大（约47.6个/mm²）;‘大叶’龙牙的淀粉粒径最大,均值为47.61 μm;‘江西’龙牙的淀粉粒大小分布更集中,差异性小。染色体核型分析结果显示：龙牙百合3个品种的染色体数目均为2n=2x=24,为二倍体,其中‘江西’龙牙核型公式为2n=2x=24=2m（2SAT）+6sm（2SAT）+12st（4SAT）+4t;‘平头’龙牙核型公式为2n=2x=24=4m+8sm+10st（4SAT）+2t;‘大叶’龙牙核型公式为2n=2x=24=2m（2SAT）+6sm+14st（4SAT）+2t,三者核型均为3B型。     

中国柯属5种资源植物潜在地理分布及其对气候变化的响应

利用最大墒模型和地理信息系统软件对柯属（Lithocarpus）5种资源植物在我国的适宜分布区进行了定量预测,并对未来不同气候情景下其分布区的变化进行了分析。结果显示：木姜叶柯（L.litseifolius（Hance）Chun.）在我国秦岭淮河以南广泛分布,短尾柯（L.brevicaudatus（Skan）Hay.）主要分布在我国亚热带中东部区域;木姜叶柯在未来气候（2061-2080年）RCP2.6、RCP8.5两种情景下适生区面积分别减少了5.1%和3.0%,而短尾柯却分别增加了0.5%和1.5%。白柯（L.dealbatus（Hook.f.et Thoms.ex DC.）Rehd.）适宜区主要分布在云南北部、四川南部,烟斗柯（L.corneus（Lour.）Rehd.）主要分布在两广省份的南亚热带地区。白柯和烟斗柯在RCP2.6情景下适生区面积分别减少了12.1%和17.8%,在RCP8.5情景下分别减少了3.5%和15.9%,这两个种的适宜区面积减少较多。厚斗柯（L.elizabethae（Tutch.）Rehd.）主要分布于广西,在两种情景下适宜区面积分别增加了7.3%和6.3%。研究结果表明,由于分布区存在差异,同属不同物种的未来分布对气候变化的响应不同。