Identification and isolation of vinculin from platelets

A vinculin-like protein was identified in chicken as well as in bovine platelets by ELISA competitive binding assay using antibodies against vinculin from chicken gizzard. By a modified procedure (J. Biol. Chem. (1980) 255, 1194–1199) we succeeded in isolating bovine platelet vinculin to apparent homogeneity. The structural identity of platelet and chicken gizzard vinculin was demonstrated by circular dichroism analysis. It was also shown that platelet vinculin induces a significant decrease in the low shear viscosity of F-actin. Vinculin, in all probability, plays an important role in the organization of actin filaments in platelets, especially in the linkages of microfilaments to the membrane.     

Isolation and characterization of lipophorin from Drosophila melanogaster larvae

The hemolymph lipoprotein lipophorin has been isolated from third-instar Drosophila melanogaster larvae by a technique that involves homogenization of whole larvae in a medium containing protease inhibitors and purification of the lipoprotein by density gradient centrifugation. Drosophila lipophorin has a density of 1.16 g/ml and is composed of 62.5% protein, 23.1% phospholipid, 7.4% diacylglycerol, 5.4% triacylglycerol, 0.9% hydrocarbon, and 0.7% sterol. As is the case with other insect lipophorins, Drosophila lipophorin contains two apolipoproteins, apolipophorin-I (M_r ≈ 275,000) and apolipophorin-II (M_r ≈ 76,000). Drosophila apolipophorin-I does not crossreact with antibodies prepared against apolipophorin-I from Manduca sexta.     

A comparative study of pheromone perception in two species of Noctuid moths

The electrical activity of single olfactory receptor neurons in male soybean looper (SBL) Pseudoplusia includens(Walker) and cabbage looper (CL) Trihoplusia ni(Hübner) moths was evaluated in response to stimulation with fixed amounts of the individual components of their respective pheromone blends. In common with earlier observations in the CL, there are at least two classes of morphologically distinct pheromone sensitive sensilla on the antenna of male SBL, each of which contains two olfactory receptor neurons. In both species, one class of sensilla contains an olfactory receptor neuron sensitive to (Z)-7-dodecen-1-ol acetate (Z-7, 12:AC), the major component in each insect's blend, and a companion receptor neuron which is sensitive to (Z)-7-dodecen-1-ol (Z7,12: OH). In both species the second class of sensilla contains an olfactory receptor neuron which is sensitive to one of the minor components of the pheromone blend. (Z)-5-dodecen-1-ol acetate (Z-5,12:AC) is an effective stimulus in SBL, whereas (Z)-7-tetradecen-1-ol acetate (Z-7,14:AC) is an effective stimulus in CL. However, these two stimulatory compounds have been identified only in the female CL gland; neither has been found in the SBL gland. Thus, in contrast to the CL, which has receptor neurons which are responsive exclusively to conspecific pheromone components, the SBL has a class of receptor neurons which is responsive to a minor component of another species' pheromone blend. Field-trapping assays in which Z-5,12:AC is added to the SBL blend suggest that this single CL component is a powerful inhibitor of male SBL behavioral responses to conspecific pheromone blends. The difference observed in the specificity of the receptor neurons in this second class of sensilla are thus believed to play an integral role in the isolation processes that are maintained between these two species and may well account for the observed behavioral differences in their responses to heterospecific pheromone blends.     

The isolation of large quantities of undamaged cellular organelles and cytosolic enzymes using a low-shear continuous tissue homogenizer

There is often a need to isolate large quantities of subcellular components such as membrane-coated organelles (e.g., nuclei, lysosomes, and mitochondria), cell membranes, and soluble (cytosolic) proteins. Instruments which can homogenize relatively large masses of tissue, primarily those with rapidly rotating blades and cylinders, are excessively vigorous, often resulting in damaged and/or low yields of the subcellular components. This paper describes procedures for obtaining high yields of undamaged subcellular components using a continuous bulk tissue homogenizer which performs with low shear (the low-shear continuous homogenizer or LSC). This homogenizer is simple in operation, durable and can be used with a variety of tissues. Fibrous tissues are more difficult to homogenize using this instrumentation and require a premincing to small pieces (0.2 to 1.0-cm diam) followed by filtration through 2-4 mesh (two to four apertures per inch). Methods for bulk preparations with enhanced recoveries of undamaged nuclei, and a typical soluble multimeric enzyme, phosphofructokinase, are presented. Electron microscope views of the homogenates show the preserved state of the other subcellular components. The LSC homogenizer requires less physical effort with no "hands on" operation and thus is safer. This homogenizer requires less homogenization time compared to the smaller, hand-held Potter-Elvehjem-type homogenizers. Operations requiring low temperature can be performed at room temperature as long as the continuously passing homogenate solutions are kept chilled.     

Highly enriched,minimally disrupted plasma membrane vesicles from aortic myocytes grown in primary culture

A plasma membrane-enriched fraction (fraction 1B) has been obtained from rat aortic myocytes grown in primary culture. Plasma membrane markers, 5′-nucleotidase and ouabain-sensitive (Na⁺ + K⁺)-ATPase, are enriched 4.1- and 8.7-fold, respectively, in this fraction. Although endoplasmic reticulum marker NADPH-cytochrome c reductase is the most enriched in mitochondrial and heavy sucrose density gradient fractions, substantial enrichment of this marker is also observed in membrane fraction 1. This membrane preparation therefore contains a certain quantity of endoplasmic reticulum. Cytochrome c oxidase is de-enriched by a factor of 0.04 in fraction 1, indicating that it is essentially clear of mitochondrial contamination. Homogenization of aortic media-intima layers using a whole-tissue technique induces greater disruption of mitochondria and subsequent contamination of membrane fractions than does the procedure for cell disruption. Analysis of electrophoretic gels, vesicle density distribution and electron micrographs of enriched membrane fractions provide evidence that plasma membrane enriched from cultured myocytes is less traumatized than comparable fractions obtained from intact tissue. The potential value of such a highly enriched, minimally disrupted plasma membrane preparation is discussed.     

Hydrogen turnover by psychrotrophic homoacetogenic and mesophilic methanogenic bacteria in anoxic paddy soil and lake sediment

Abstract The effect of temperature on CH₄ production, turnover of dissolved H₂, and enrichment of H₂-utilizing anaerobic bacteria was studied in anoxic paddy soil and sediment of Lake Constance. When anoxic paddy soil was incubated under an atmosphere of H₂/CO₂, rates of CH₄ production increased 25°C, but decreased at temperatures lower than 20°C. Chloroform completely inhibited methano-genesis in anoxic paddy soil and lake sediment, but did not or only partially inhibit the turnover of dissolved H₂, especially at low incubation temperatures. Cultures with H₂ as energy source resulted in the enrichment of chemolithotrophic homoacetogenic bacteria whenever incubation temperatures were lower than 20°C. Hydrogenotrophic methanogens could only be enriched at 30°C from anoxic paddy soil. A homoacetogen     

Evidence for O-acetylserine in Nicotiana tabacum

O-Acetylserine, a precursor of cysteine in plants, was isolated from cells of Nicotiana tabacum cultured in liquid medium.     

黔产大青化学成分及其抗菌活性研究

大青(Clerodendrum cyrtophyllum)是苗族地区常用的药用植物。为研究黔产大青的化学成分及其抗菌活性，该研究采用大孔吸附树脂、反相柱色谱、硅胶柱色谱、Sephadex LH-20柱色谱、半制备高效液相色谱等方法对大青95%乙醇提取物进行分离和纯化，并根据波谱数据鉴定所得化合物结构，采用MTT法评价其抗菌活性。结果表明：从大青中分离得到18个化合物，分别鉴定为木栓酮(1)、α-amyrin palmitate(2)、sambuculin A(3)、22-dehydroclerosterol(4)、isopetasin(5)、taraxasteryl palmitate(6)、豆甾醇(7)、22-dehydroclerosterol-3-O-β-D-(6′-O-margaroyl)-glucopyranoside(8)、3-O-β-D-galactopyranosyl-(24β)-ethylcholesta-5,22,25-trien(9)、肉苁蓉苷D(10)、tortoside F(11)、balanophonin(12)、木犀草苷(13)、类叶升麻苷(14)、木犀草...     

Strong genetic differentiation and postglacial origin of populations in the marine midge Clunio marinus (Chironomidae,Diptera)

The marine midge Clunio marinus (Chironomidae, Diptera) is characterized by a one‐dimensional distribution along the European Atlantic coast, where its lunar and circadian emergence rhythms are genetically adapted to the local tidal regimes, resulting in a series of ‘temporal races’. Clunio marinus is restricted to rocky coasts and thus the temporal races occur in different rocky patches. We studied 10 populations of Clunio marinus from five different regions, spanning the major rocky mainland coasts from Spain to Norway, using amplified fragment length polymorphisms (AFLP), microsatellites and mitochondrial cytochrome oxidase I (COI) sequences. Star‐like patterns of COI haplotypes within regions indicate postglacial colonization. A high degree of shared polymorphisms in AFLP markers suggests colonization from a single source, implying postglacial evolution of timing adaptations in relation to the local tidal regime. In contrast, no COI haplotypes are shared among regions. We hypothesize that different levels of differentiation of nuclear vs. mitochondrial markers in the source region were carried forward during postglacial expansion. Despite the recent origin of populations, all markers reveal distinct genetic differentiation between rocky coasts on a scale of 650–1150 km. Differentiation between rocky coasts is not correlated to timing adaptations, suggesting that geographic isolation is prevalent between rocky coasts and that this facilitated the evolution of local timing adaptations. At the same time there is little genetic differentiation within rocky coasts on a scale of 2–6 km; leaving open the possibility that within rocky coasts with large variation in tidal regimes, temporal adaptations evolved in the face of gene flow.     

Adaptive radiation through phenological shift: the importance of the temporal niche in species diversification

Abstract 1. Phenological shift in oviposition in seed predators may be a key factor for adaptive radiation if temporal differences lead to less intense competition. 2. This hypothesis was tested at two sites in the French Alps in three sympatric species of larch cone flies grouped into two phenological groups (early and late) differing in adult emergence and oviposition timing by approximately 2 weeks. The present study assessed the intensity of competition within and between groups by measuring four larval traits. Cone traits were measured, and the impact of early species parasitism on cone development was assessed. 3. The occupation of the central axis of a developing cone by one early larva has a strong detrimental effect on cone growth and seed production. However, there was almost no correlation between the variables measured on the cones and on the larvae, suggesting that the resources available were not limiting. 4. Inter‐group competition had no significant effect on early larvae. In contrast, both inter‐ and intra‐group competition had a significant negative effect on late larvae length (–11% and –16% respectively), dry mass (–8% and –23%), and lipid mass (–15% and –26%). The intensity of competition was stronger among larvae in the same phenological group, which is consistent with the hypothesis that shifts in oviposition promote adaptive radiation in larch cone flies by reducing competition among larvae.