Bean lectins

Summary Single seeds of over 100 bean cultivars were analyzed by two-dimensional electrophoresis. The cultivars could be classified into eight groups by virtue of their G2/albumin electrophoretic patterns: T_G2, S_G2, V_G2, Pr_G2, B_G2, M_G2, P_G2, and Pi_G2, The polypeptide compositions of these types were largely inter-related having particular polypeptides in common. It was possible to correlate the G2/albumin patterns with agglutinating activity of cow and rabbit blood cells as measured by the agglutination ratio (minimum concentration of extract required to agglutinate cow blood cells: minimum concentration of extract required to agglutinate rabbit blood cells). The active lectin polypeptides were identified by extracting lectins from agglutinated erythrocytes and by comparing the qualitative similarities and differences of the G2/albumin patterns and their agglutination activities. A reference catalogue of over 100 bean cultivars giving their phaseolin and G2/albumin electrophoretic patterns, and agglutination ratios is presented.     

Follicle cell regulation of protein synthesis and developmental competence in sheep oocytes

The developmental capacity of sheep oocytes cultured outside the follicle was greatly increased by the presence of high concentrations of gonadotrophins (10 micrograms/ml) in the medium. However, even under these conditions, the developmental capacity of the oocytes was only half that of oocytes cultured within the intact follicle. The presence of the cumulus was essential for development; nearly all denuded oocytes failed to undergo cleavage. Maturational changes in the oocyte involving increased amino acid uptake increased incorporation and specific changes in protein synthesis were inhibited by the follicle cells; this suppression was alleviated by gonadotrophic hormones. The cumulus cells suppressed amino acid incorporation and, to some extent, the changes in protein synthesis. However, the suppression of amino acid uptake required the presence of the whole follicle. Patterns of protein synthesis by oocytes cultured outside the follicle differed from those in oocytes cultured within the follicle, irrespective of the presence of the cumulus or gonadotrophins. Analysis of single oocytes cultured outside the follicle showed that the protein profiles varied markedly even under identical culture conditions.     

The growth of rhododendrons in containers in soil,treated with either CaCO3, Ca(OH)2 or CaSO4

Summary Rhododendrons were grown in containers for a period of six and a half years (six growth cycles) in soil mixes which contained liberal amounts of either CaCO₃, Ca(OH)₂ or CaSO₄.No evidence was obtained to suggest that the plants were sensitive to liming of the soil or to excessive applications of calcium. The only reaction observed was a leaf chlorosis and veinal necrosis which developed for a brief period following the heavy application of CaSO₄ in the fifth season. The application of Ca(OH)₂ raised the pH throughout the soil profile to over 7, and CaSO₄ induced a consistent increase in leaf calcium.     

Contraction of isolated airway smooth muscle by synthetic leukotrienes C4 and D4

The pharmacology of leukotrienes (LT) C4 and D4 in isolated airway smooth muscle was investigated. In rat trachea, neither LTC4 or D4 elicited a response. In contrast, LTC4 was a potent contractile agonist in guinea-pig trachea, bronchus and parenchymal lung strip. Similar effects were obtained with LTD4 in trachea and parenchyma. In trachea and bronchus, the concentration-response curve to LTC4 was biphasic: indomethacin converted the biphasic response curve to a simple sigmoidal shape and enhanced the maximum contractile response. The SRS-A antagonist FPL 55712 antagonized the effect of LTD4 in both trachea and parenchyma. As regards LTC4-induced contraction of trachea and bronchus, FPL 55712, depending on concentration, either antagonized, or antagonized and enhanced the maximum contractile response. The enhancement of the maximum contractile response by FPL 55712 was not apparent when indomethacin was present. FPL 55712 failed to antagonize the effect of LTC4 in parenchyma.     

Serum lipoproteins and albumin in the lecithin: Cholesterol acyltransferase reaction

The unique features of pig ovarian follicular fluids, i.e., presence of high density lipoprotein (HDL) only and lecithin: cholesterol acyltransferase (EC 2.3.1.43; LCAT) activity, provides a good model to study the effect of serum lipoproteins and serum albumin on the LCAT reaction. $\text{In}\text{vitro}$ cholesterol esterification is enhanced when very low density lipoprotein (VLDL) and low density lipoprotein (LDL) fractions are added, but is inhibited when one or the other of these lipoproteins is absent. High concentrations of HDL₂ result in decreased activation which can be compensated for by the addition of the VLDL-LDL mixture. These findings suggest that the rate of cholesterol esterification in ovarian follicular fluid may be enhanced by providing the exogenous VLDL and LDL as the recipients of HDL-cholesteryl ester. The inhibition of LCAT activity caused by free fatty acid and lysophosphatidylcholine can be partially reversed by the addition of serum albumin, suggesting that serum albumin may regulate the LCAT reaction.     

Analysis of actin and microfilament-associated proteins in the mitotic spindle and cleavage furrow of PtK2 cells by immunofluorescence microscopy: A critical note

The distribution of actin and the microfilament-associated proteins myosin and tropomyosin was studied in mitotic PtK2 cells. Using fluorescent heavy meromyosin and two different antibodies against actin we have found no evidence for increased accumulations of actin in the mitotic spindle but have found increased levels of actin in the cleavage furrow and the contractile ring. Short, thin microfilament pieces remain detectable in the cytoplasm throughout mitosis. Purified antibodies against myosin and tropomyosin also revealed no increased levels of these proteins in the spindle region, although both proteins were found in the contractile ring and areas of the cytoplasm close to the intercellular bridge. These data are in agreement with functional and ultrastructural studies involving a role for actin and microfilament-related proteins in cytokinesis. They do not support models in which microfilament-related proteins are assumed to be a major constituent of the mitotic spindle.     

Quantitative aspects of RNA synthesis in normal and lithium-treated embryos ofXenopus laevis

Summary The treatment ofXenopus early embryos with lithium chloride produces exogastruale — embryos which fail to gastrulate normally and in which the rates of cell division are reduced. In the present study estimations of incorporations of (5-³H) uridine and the specific activities of the 5-ribonucleotide precursor pools showed that exogastrulae have higher rates of RNA synthesis per cell than control neurulae. Sub-cellular fractionations showed that a greater proportion of labelled RNA was retained in the nuclei of exogastrulae than of neurulae, while neurulae showed a greater incorporation into polysomes.     

Rapid and efficient separation and identification of the two molecular forms of human adenosine deaminase by thin-layer gel filtration chromatography

Two molecular forms of adenosine deaminase have been found in human tissues. The column gel filtration method has been used for the separation of the two enzyme forms. Routine separation and analysis of the enzyme forms based on the molecular size difference can be achieved by thin-layer gel filtration on Sephadex G-200 superfine gel. The thin-layer method has been found to be more rapid and efficient than the column method. Enzymes in crude preparations can be studied effectively with the thin-layer method.     

Intracellular localization of GDP-l-fucose: Glycoprotein and CMP-sialic acid: Apolipoprotein glycosyltransferases in rat and pork livers

A GDP-l-fucose:glycoprotein fucosyltransferase which transfers l-fucose to terminal β-N-acetyl-d-glucosaminyl residues of sialidase-, β-galactosidase-treated α₁-acid glycoprotein and a CMP-sialic acid:glycoprotein sialyltransferase acting on sialidase-treated apolipoprotein-Ala₁ from human very low density lipoprotein have been shown to be concentrated in rat liver Golgi apparatus preparations at enrichments of 40- and 45-fold, respectively, and in pork liver Golgi-rich fractions at enrichments of 35- and 20-fold, respectively. A second fucosyltransferase acting on sialidase-treated α₁-acid glycopretein was absent from rat liver and was enriched only 13-fold in a pork liver Golgi-rich fraction. The smooth-surfaced microsome fraction was the only other rat liver subcellular fraction with appreciable levels of the GDP-l-fucose: β-N-acetyl-d-glucosaminide fucosyltransferase and the lipoprotein sialyltransferase (enrichments of 2.6- and 5.2-fold, respectivley). This enrichment could not be attributed to the plasma membrane content of the smooth microsome fraction since plasma membrane fractions from rat liver were shown to have relatively low concentrations of these two transferases (enrichments of 0.3 or less). Rat liver plasma membrane was also shown to have similarly low relative specific activities for three other glycosyltransferases (sialyl-, galactosyl-, and N-acetylglucosaminyl-). The accurate determination of the glycosyltransferase activities of the plasma membrane fraction required the use of relatively low concentrations of plasma membrane and relatively high concentrations of nucleotide-sugars in order to avoid interference by the high nucleotide-sugar pyrophosphatase and hydrolase activities of this fraction.     

Distribution of actin and tubulin in cells and in glycerinated cell models after treatment with cytochalasin B (CB)

The organization of microfilaments and microtubules in cultured cells before and after the addition of cytochalasin B (CB) was studied both by electron microscopy and immunofluorescence microscopy using antibodies specific for actin, tubulin and tropomyosin. CB induces a rapid disorganization of normal microfilament bundles. Star-like patches of actin and tropomyosin are visualized in immunofluorescence microscopy and dense aggregates of condensed microfilaments are seen in electron microscopy. The integrity of the microtubules is not changed by CB treatment. Addition of CB to glycerinated cells, in contrast to normal cells, does not result in the disorganization of microfilament bundles. CB-treated glycerinated models can still contract upon addition of ATP. Thus the CB-induced rearrangement of microfilament bundles occurs only in vivo and not in glycerinated cell contractility models.