Lipoprotein lipase activity of rat cardiac muscle. The intracellular distribution of the enzyme between fractions prepared from cardiac muscle and cells isolated from the hearts of fed and starved animals.

1. Subcellular fractions, characterized by using morphological, compositional and enzymic markers, were prepared from rat heart tissue and cells isolated from the hearts of fed and 24 h-starved rats. 2. The lipoprotein lipase activity of fractions from whole tissue and isolated cells was determined in either fresh fractions or in acetone/diethyl ether powders of the fractions. 3. Lipoprotein lipase activity was present in all the fractions from tissue and cells, but was found to be of highest relative specific activity in the microsomal () fractions. 4. In fractions prepared from the isolated cells of hearts from starved rats the proportion of the total lipoprotein lipase present and its relative specific activity in the microsomal fraction were greater than in the equivalent fractions from fed animals. 5. The enhancement of lipoprotein lipase activity as a result of the acetone/diethyl ether powder preparation of fractions was most extensive in the microsomal fractions. 6. Investigation of the microsomal fraction showed that the lipoprotein lipase activity present was in two pools, one of which was within endoplasmic-reticulum vesicles. 7. The observations were consistent with the possibility that the cardiac-muscle cell could be the origin of the lipoprotein lipase activity functional in triacylglycerol uptake by the heart.     

Countercurrent-distribution studies on histones

1. The possibilities of fractionating histones and histone fractions by means of countercurrent distribution between two phases formed by water and butan-2-ol, in the presence of various concentrations of trichloroacetic acid, have been examined. 2. Although the principal histone fractions differ considerably in their partition ratios, a satisfactory resolution of the principal histone fractions from the whole histone has not been achieved. 3. The histone fractions obtained by other methods can be resolved with suitable concentrations of trichloroacetic acid. Besides the main peak several subsidiary peaks are obtained in most cases, the composition of which corresponds with others of the main fractions. 4. The method is therefore capable of removing from the principal fractions as previously prepared contamination by other fractions. 5. Except in one case, no fraction with composition unlike other fractions has been obtained. In several cases the material isolated from the principal peak behaves as a single component on running again. In two cases fractions with similar compositions were distinguished by countercurrent distribution.     

Heterogeneity of pig plasma amine oxidase: molecular and catalytic properties of chromatographically isolated forms

Pig plasma amine oxidase was resolved into several fractions by ion-exchange and hydroxyapatite chromatography. These fractions were separately purified, and each fraction was analyzed for catalytic and structural properties. The relative amount of these fractions varied between preparations. Each fraction was composed of a unique set of bands on isoelectric focusing, as revealed by activity and protein staining. All the fractions contained 2 mol of Cu2+ and one "active-carbonyl" cofactor per 195 000 g of protein. There was no detectable difference in the amino acid contents of the fractions. The fractions all had similar catalytic properties using benzylamine as the substrate. The chromatographically resolved fractions had differing carbohydrate contents as revealed by gas chromatographic analysis and interaction with lectins. Further, some of the isoelectric focusing bands interacted with lectins of differing affinities. The results suggest that the heterogeneity may be due to variable carbohydrate content. Further, the practice of pooling the various chromatographic fractions may yield misleading results under certain circumstances.     

Fractionation of Chromatin Depleted of Histone H1

Chromatin depleted of histone HI was prepared after extraction with 0.6 M NaCl. The salt-extracted chromatin was mechanically fragmented, then fractionated on sucrose gradients in two fractions, the fast migrating (heavy) and the slow migrating (light) fractions. The average sizes of the ONA-moieties from heavy and light fractions were found to be similar. However, heavy fractions were enriched in high temperature melting populations, whereas, light fractions exclusively included low temperature melting populations, not seen in the heavy fractions. Comparison of the derivative plots of thermally denatured whole and salt-extracted chromatin as well as heavy and light fractions of salt-extracted chromatin suggests that the DNA regions associated with histone HI in intact chromatin may be co-isolated with the light fraction.     

Uridine Transport and Metabolism in the Central Nervous System

Myelin and myelin-containing (P3) fractions were prepared from human white matter by discontinuous sucrose gradient centrifugation. The myelin isolated from each of the fractions of different densities was morphologically and biochemically distinct. Light myelin fractions consisted of compact, multilamellar myelin, whereas the denser fractions consisted predominantly of loose myelin with fewer lamellae. The amounts of both basic protein and lipophilin (proteolipid protein) were reduced in the denser fractions. In contrast, the high-molecular-weight components were elevated in the dense fractions. The lipid composition was similar in all the fractions studied. Analysis of basic protein by gel electrophoresis at pH 10.6 revealed differences in basic protein microheterogeneity among the fractions. The light myelin fraction was enriched in the more positively charged basic protein components (components 1, 2, and 3), whereas these components were reduced in the denser fractions. Myelin in the dense fractions was enriched in the more modified forms of basic protein (components 6, 7, and 8). The pattern of microheterogeneity was different for basic protein isolated from myelins of a 2-year-old and an adult brain; the former showed fewer components and mainly the most cationic species. On the other hand, the pattern of microheterogeneity of basic protein isolated from the different density gradient fractions was similar for both ages.     

Some features of the bacterial membrane studied with the aid of a new fractionation technique

Membranes of Bacillus megaterium and other bacteria were bound to crystals of cadmium lauroylsarcosinate and were resolved into nine lipoprotein fractions by elution with potassium chloride and sodium deoxycholate solutions. The fractions differed widely in protein/lipid ratio. Some major protein species were probably common to all the fractions, but the phospholipid composition showed some variation. Electron-microscopic examination after negative staining revealed that material in certain fractions was in the form of particles of diameter about 12nm, and other fractions consisted of amorphous aggregates. The composition of the membrane in terms of the nine fractions was influenced markedly by the conditions of culture of the bacteria. Radioactive-labelling experiments suggested that some fractions served as precursors of others, and one fraction appeared to contain the attachment points of the DNA.     

Effect of cations on the reconstitution of heavy subchloroplast fractions (grana) in disorganized low-salt agranal chloroplasts

The disorganization of grana in spinach chloroplasts and their reconstitution has been studied by varying their ionic environment. Dissociation in low-salt media and reconstitution by added cations (monovalent or divalent) was correlated with the formation in high yield of light or heavy subchloroplast membrane fractions, respectively, produced after digitonin treatment of chloroplasts. The formation of heavy subchloroplast fractions was dependent on cation concentration and reached a plateau at 0.1 m monovalent cation or 0.002 m divalent cation. The cation reconstituted fractions recovered the composition and activities of the respective fractions obtained from control chloroplasts. Cation addition to light subchloroplast fractions isolated from low-salt agranal chloroplasts after digitonin disruption also produced heavy fractions. Divalent cations were more effective than monovalent. The heavy fractions produced were enriched in Chlorophyll b and photosystem II activity while the light fractions were enriched in Chlorophyll a and photosystem I activity. The mechanism by which cations induce formation of heavy subchloroplast fractions is not osmotic. Upon reconstitution, stacking of thylakoids seems to occur at specific membrane binding sites.     

Amino acid composition and affinity to oxygen of domestic duck hemoglobins

The method of disk-electrophoresis in PAAG has shown that hemoglobin of domestic ducks is heterogeneous and consists of four electrophoretically homogeneous fractions: two fractions with high content of protein and two minor fractions. They differ in the content of lysine, histidine, serine, glycine, glutamic acid, tyrosine and phenyl alanine as well as in affinity to molecular oxygen. The minor fractions are characterized by low and high affinity to oxygen and fractions with high content of protein occupy an intermediate position.     

Enzyme distribution and transport activities in electrophoretically isolated fractions of the muscle sarcotubular system

A simple electrophoretic method is introduced allowing to isolate five fractions of skeletal muscle ST-system vesicles. In a previous study differences in lipid content, 3H-ouabain binding and in presence of triads in individual fractions (Lehotsky et. al. 1986) were analysed. In the present study biochemical characterization was extended, and (in accordance with previous results) major differences were observed to exist between fraction 1 and fractions 3 and 4. SDS-PAGE showed that fractions 3 and 4 were enriched in a protein with m.w. 100 kD, these fractions showing the highest specific activities of (Mg2+ + Ca2+)-ATPase and oxalate-supported Ca2+-uptake; activities of Mg2+-ATPase and surface membrane marker enzymes were the lowest in these fractions. On the other hand, in fraction 1 the highest activities of Mg2+-ATPase and marker enzymes of the surface membrane were observed together with a decreased content of the 100 kD protein and activities of Ca2+ transport. It could be concluded that the method is suitable to differentiate between relatively pure SR (fractions 3 and 4) and fractions rich in sarcolemma or T-tubules components (fractions 1 and 5).     

Distribution of phosphatidylinositol biosynthetic activities among cell fractions from rat liver.

The distribution of activities for synthesis of phosphatidylinositol among cell fractions from rat liver was determined. Activity was concentrated in endoplasmic reticulum; rough and smooth fractions were nearly equal. Golgi apparatus exhibited a biosynthetic rate 44% that of endoplasmic reticulum. Plasma membranes and mitochondrial fractions were only 6% as active as endoplasmic reticulum. Thus, endoplasmic reticulum and Golgi apparatus fractions from rat liver catalyze the net synthesis of phosphatidylinositol in vitro, whereas plasma membrane and mitochondrial fractions do not.     

Uptake of taurine into subcellular fractions of C-6 glioma cells.

Subcellular fractions from cultured C-6 glioma cells prepared by methods similar to those for crude synaptosomal fractions of rat cerebral cortex accumulated [³⁵S]taurine as did intact glioma cells. Thus, the accumulation of taurine was dependent on temperature and sodium concentration and sensitive to osmotic shock. The kinetic properties of this uptake are characterized by an apparent K_m, of about 25 μm, The properties of taurine uptake into subcellular fractions from C-6 glioma cells were compared with those of crude synaptosomal fractions and differences could be observed in temperature sensitivity and with metabolic inhibitors, which were less potent in the glioma preparation. Equilibrium density gradient centrifugation of subcellular fractions from glioma cells revealed that particles containing [³⁵S]taurine sediment to a lower buoyant density than mitochondria. But on co-sedimentation of subcellular fractions from glioma cells with synaptosomal fractions derived from cerebral cortex, differences in the buoyant density between these two preparations could be found. The findings support the possibility of a contamination of synaptosomal fractions with subcellular fractions derived from glial origin.     

山鸡椒植物源抑菌成分的筛选研究

以山鸡椒为植物材料,以活性追踪的方法测定了不同组分对几种植物病原菌的抑制活性,并从中分离纯化出一种有效抗菌物质L1。实验结果表明:粗提物不同萃取相中,乙酸乙酯相的抑制作用最好,其对杨树溃疡病菌和苹果霉心病菌抑制率达到75%以上;乙酸乙酯相各个组分对几种植物病原真菌均有一定的抑制活性,其中组分6和组分7抑菌效果强,组分6对苹果霉心病菌抑制率达到100%,组分7对番茄灰霉病菌抑制率达到100%;而对抑菌活性物质L1的抑菌活性研究中,随着L1浓度逐渐升高,对几种病原菌的抑制作用也依次增强,尤其是对苹果霉心病菌的抑制效果更加明显,在供试浓度为0.1 mg/mL时,抑制率达到100%;活性成分L1最终通过波谱学方法和文献对比确定为5,8-二羟基-67,-二甲氧基黄酮。     

The fractional precipitation of soil humic acid by ammonium sulphate

Summary A number of fractions have been obtained from a soil humic acid by salting-out and by leaching with ammonium sulphate. The fractions obtained are characterised by infra-red and ultra-violet spectroscopy and osmometry. The fractions removed at relatively low saturation with ammonium sulphate are less highly charged and contain more aliphatic hydrocarbon groups per unit weight than the fractions precipitated at high concentrations of salt. In addition, the number average molecular weight of successive fractions precipitated with ammonium sulphate decreases significantly.     

Membrane-free scrapie activity.

Determinations of scrapie activity in subcellular fractions from infected hamster brains through the asymptomatic and symptomatic course of infection revealed the presence of substantial amounts of scrapie infectivity in the 100,000 X g supernatant fractions, indicating that association with physically discernible membrane structures is not necessary for the transmission of the scrapie agent. An increase of scrapie infectivity in the 100,000 X g supernatant fractions after vigorous homogenization of infected membrane-rich fractions suggests that the agent is identical in membrane-rich and 100,000 X g supernatant fractions.     

SUBCELLULAR LOCALIZATION OF PROTEIN CARBOXYL-METHYLASE AND ITS SUBSTRATES IN RAT PITUITARY LOBES

Subcellular distribution of protein carboxyl-methylase (PCM) and its endogenous substrates the methyl acceptor proteins (MAP) have been studied in the anterior, the posterior and the intermediate lobes of the rat pituitary gland. In all three lobes, PCM was found to be a cytosolic enzyme whereas the highest MAP specific capacity was observed in the lysate of the granular fractions. The methylated proteins from the lysates of the granular fractions and the cytosolic fractions were analyzed with a novel electrophoretic system which prevents the hydrolysis of the protein-methyl esters. Gel electrophoretic profiles from the lysates of the granular fractions were different from those of the cytosolic fractions. In the lysatcs of the granular fractions. the MAP had a molecular weight of less than 25,000 suggesting that the methylated polypeptides in these fractions were the pituitary peptide hormones (and their subunits) and neurophysins.     

Metabolism of tritiated water in the cell nucleus and intracellular substances of the rat

Tritiated water was given to rats in single oral doses, and the cell fractions for each organ were prepared by ultracentrifugation for measurement of the concentration of tissue-bound tritium. The concentration of tissue-bound tritium reached a peak relatively soon after intubation, 1-4 days after administration. The initial concentration of tissue-bound tritium in liver and kidney was high in the mitochondrial and microsomal fractions but low in the nuclear and cytosol fractions. The initial tissue-bound tritium concentration in the brain was high in the mitochondrial and microsomal fractions but low in the nuclear and cytosol fractions. The initial concentration of tissue-bound tritium in the testes was high in the mitochondrial, microsomal, and cytosol fractions but low in the nuclear fraction. The half-life for the long component was larger in the nuclear, mitochondrial, and microsomal fractions of the brain than in the other organs according to an interorgan comparison of each fraction. As for the testes, the values for the mitochondrial and microsomal fractions were larger than those for the other organs.     

Studies on the proteins of Poekilocerus pictus. II--changes taking place in the haemolymph protein during maturation of female

In all, 7 protein fractions have been detected in the haemolymph of Poekilocerus pictus by the polyacrylamide gel disc electrophoresis. Out of seven protein fractions, four fractions i.e.3,4,5 and 6 take major role in the vitellogenesis. These fractions are accumulated in the ovariectomised female insect. No yolk is deposited in the allatectomised female ovary. The protein fractions 4, 5 and 6 show high concentration of protein in the allatectomised female as compared to the show operated female. It is concluded that the synthesis of protein fraction 3 is controlled by the corpora allata while the fractions 4, 5 and 6 are controlled by the neurosecretory cells.     

An ERP Study of the Processing of Common and Decimal Fractions: How Different They Are

This study explored event-related potential (ERP) correlates of common fractions (1/5) and decimal fractions (0.2). Thirteen subjects performed a numerical magnitude matching task under two conditions. In the common fraction condition, a nonsymbolic fraction was asked to be judged whether its magnitude matched the magnitude of a common fraction; in the decimal fraction condition, a nonsymbolic fraction was asked to be matched with a decimal fraction. Behavioral results showed significant main effects of condition and numerical distance, but no significant interaction of condition and numerical distance. Electrophysiological data showed that when nonsymbolic fractions were compared to common fractions, they displayed larger N1 and P3 amplitudes than when they were compared to decimal fractions. This finding suggested that the visual identification for nonsymbolic fractions was different under the two conditions, which was not due to perceptual differences but to task demands. For symbolic fractions, the condition effect was observed in the N1 and P3 components, revealing stimulus-specific visual identification processing. The effect of numerical distance as an index of numerical magnitude representation was observed in the P2, N3 and P3 components under the two conditions. However, the topography of the distance effect was different under the two conditions, suggesting stimulus specific semantic processing of common fractions and decimal fractions.     

Ivermectin resistant and susceptible third-stage larvae of Haemonchus contortus: cholinesterase and phosphatase activities

Cholinesterase and acid phosphatase (AP), but not alkaline phosphatase activities, were detected in cytosolic and membrane-bound fractions of ivermectin resistant and susceptible Haemonchus contortus infective-stage larvae. Some differences in acetylcholinesterase activity of cytosolic fractions and in the AP activity of these fractions as well as in the response to AP inhibitors by membrane-bound fractions were detected. Data are discussed.     

A method for estimating the nearest neighbor base-pair content of RNAs using CD and absorption spectroscopy.

CD and absorption spectra are sensitive to the secondary structure of RNAs. By fitting the spectra contained in our basis set to the CD and absorption spectra of an RNA of known sequence, we could determine the fractions of base pairs, the fractions of each of the nearest neighbor base pairs, and the fractions of the single-stranded nucleotides in that RNA. The basis set included 58 CD and 58 absorption spectra. The fitting was done with a guided selection routine. The estimated error was about 0.05 for predicting the fractions of the nearest neighbor base pairs, 0.06 for predicting the fractions of A.U, G.C, and G.U base pairs, and 0.04 for predicting the fractions of the single-stranded nucleotides.