Preparation of desulphated bovine fibrinopeptide B and demonstration of its sulphation in vitro by an enzyme system from neuroblastoma-glioma hybrid cells

A method is described for isolating bovine fibrinopeptide B (bFPB) in a highly purified form from crude bovine fibrinogen, using ion-exchange chromatography on DEAE cellulose. Desulphated bFPB (designated DSbFPB) was prepared by treatment of the product with acid. After incubating DSbFPB with [35S]PAPS, in the presence of a particulate preparation from neuroblastoma-glioma hybrid cells, radioactivity was incorporated into a product identified as [35S]bFPB from its position of elution on reverse-phase HPLC. The possible significance of this observation is discussed.     

Cytological studies of triploids and their progeny from male-sterile (ms1) soybean

Summary Triploids (2n=3X=60) were obtained from genetic male-sterile (ms1 ms1) soybean [Glycine max (L.) Merr.] plants. Meiosis, pollen fertility, and chromosome number of their progeny were studied. Studies of meiosis in fertile and sterile triploids revealed no distinguishable differences in chromosome associations. Male-sterile plants formed coenocytic microspores characteristic of the ms1 mutant. Restitution of some dyad and tetrad nuclei were observed in male-sterile plants. Chromosomes of the triploids tended to occur in trivalents during diakinesis and metaphase I (MI), but multivalents, bivalents, and univalents also were observed. Average types and frequencies of chromosome associations per cell in diakinesis and MI from 542 pollen mother cells were 0.004 IX + 0.06 VI + 0.002 V + 0.005 IV + 16.99 III + 1.79 II + 5.03 I. Some secondary associations, nonhomologous pairing, and aberrant nucleolar distributions occasionally were observed. Such behavior support the hypothesis of duplicated genomes and the polyploid origin of soybean. Pollen fertility in male-fertile triploid plants (Ms1 ms1 ms1) varied from 57% to 82%, with an average of about 71%. Chromosome numbers of progenies obtained from these fertile triploids varied from 2n=40 to 2n=71, and exhibited a near-random distribution, with the majority (about 60%) being between 56 and 65. Progenies of the fertile triploids gave segregation ratios for the ms1 allele, which confirmed the Ms1 ms1 ms1 genotype.Joint contribution: Agricultural Research Service, U.S. Department of Agriculture, and Journal Paper No. J-11672 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011, USA, Project 2471     

Alanine and inter-organ relationships in branched-chain amino and 2-oxo acid metabolism

Branched-chain amino acid metabolism in skeletal muscte promotes the production of alanine, an important precursor in hepatic gluconeogenesis. There is controversy concerning the origin of the carbon skeleton of alanine produced in muscle, specifically whether it is derived from carbohydrate via glycolysis (the glucose-alanine cycle) or from amino acid precursors (viz. glutamate, valine, isoleucine, methionine, aspartate, asparagine) via a pathway involving phosphoenolpyruvate (PEP) carboxykinase and pyruvate kinase, or NADP-malate dehydrogenase (malic enzyme). The relevant literature is reviewed and it is concluded that neogenic flux from amino acids is unlikely to be of major quantitative importance for provision of the carbon skeleton of alanine either in vitro or in vivo. Evidence is presented that branched-chain amino acid oxidation in muscle is incomplete and that the branched-chain 2-oxo acids and the products of their partial oxidation (including glutamine) are released. The role of these metabolites is discussed in the context of fuel homeostasis in starvation.     

The T cell receptor: the alpha and beta chains define idiotype, and antigen and MHC specificity

Three independent T cell hybridomas were isolated that have identical specificities for antigen and products of the major histocompatibility complex (MHC). All three react with the same clone-specific antireceptor antibody, and Southern blots show all three contain the same rearranged alpha and beta genes. Variants of one of these hybridomas, DO-11.10, were isolated that had lost the ability to respond to antigen plus MHC. These proved to have lost the DO-11.10-specific alpha or beta genes or both. Fusion of alpha-loss variants to beta-loss variants restored reactivity. These results indicate that the specific recognition of antigen plus MHC is determined solely by the alpha/beta-containing T cell receptor.     

Changes in lung volume and deflation stability in hyaline membrane disease

Total lung capacity (TLC), inspiratory capacity, functional residual capacity, and deflation stability of prematurely delivered Macaca nemestrina primates were measured serially during development of, and recovery from, hyaline membrane disease (HMD) to relate changes in lung volumes to changes in deflation stability. Gestational age-matched primates that did not develop HMD served as controls. TLC, measured by N2 washout, fell at 2-12 h of age (P less than 0.0001) in animals with HMD and remained lower than controls for at least 48 h (P less than 0.005). However, deflation stability, defined as the fraction of TLC remaining upon deflation to 10 cm H2O, improved from 2 to 12 h of age (P less than 0.001). Postmortem studies confirm the measurements of TLC and deflation stability and provide evidence that interstitial thickening and obstruction of air spaces with debris may be partially responsible for the observed changes in TLC in primates that develop HMD. It has been assumed that TLC is reduced in HMD because of atelectasis from elevated alveolar surface tension, but the sequential measurements in these animals suggest that other mechanisms also contribute.     

Time dependent effect of indomethacin on the stimulation of protein synthesis in isolated rabbit muscle by insulin

Insulin (100 U/ml) stimulated protein synthesis and PGF₂ release in isolated rabbit muscle, but had little effect on the rate of protein degradation. The effect of insulin persisted for at least 5 h after removal of the hormone. Indomethacin, added at the start of the incubation, inhibited the stimulatory effect of insulin on protein synthesis and PGF₂ release, but did not block the binding of iodinated insulin. When added 2 h after insulin, indomethacin did not inhibit the stimulation of protein synthesis but completely inhibited the increase in PGF₂ release. The results suggest that the stimulation of protein synthesis by insulin is mediated by metabolites of membrane phospholipids but that these changes are involved during the phase of response that immediately follows the binding of insulin to its receptor.     

Living Vessel Elements in the Late Metaxylem of Sheathed Maize Roots

The two types of nodal roots of field-grown maize, sheathedand bare, were found to have such different water conductivitiesthat an investigation of the anatomy of their large metaxylemvessels was made. While the vessels of the bare roots were openfor scores of centimetres, those of the sheathed roots werefound to be not vessels but developing vessel elements, withcross walls at 1 mm intervals, and protoplasts. The cross wallsbetween the elements had several unique histochemical properties.Previous investigators have often failed to find the cross wallsbecause they are very easily dislodged during the usual methodsof tissue preparation. They are best identified by microdissectionof fresh xylem. The living elements persist in the late metaxylemup to 20 – 30 cm from the tip. As the roots become longerthan this both the cross walls and the soil sheaths disappearand there is a transition to a bare root with open vessels inthe proximal region. The soil sheath persists a little longerthan the cross walls. The two types are thus stages in a developmentalsequence through which all nodal roots pass. A fundamental differencebetween the two types is in their water status, since the estimatedconductive capacity of a bare root is about 100 times greaterthan that of a sheathed root. These observations point to theneed for a reassessment of the published work on transport ofions into the xylem of grass roots through a reinvestigationof the ‘maturity’ of their xylem vessels. Grass roots, dimorphic roots, ion secretion to xylem, soil sheaths, xylem vessels, xylem differentiation, water conduction, Zea mays L     

Inhibition of exogenous NADH oxidation in plant mitochondria by chlorotetracycline in the presence of calcium ions

Chlorotetracycline inhibits the uncoupled oxidation of exogenous NADH by Jerusalem artichoke (Helianthus tuberosus L.) mitochondria extensively (over 80%) and rapidly (inhibition complete in 10 s) in the presence of added Ca²⁺. Half-maximal inhibition is observed at 15 μM chlorotetracycline in the presence of 2 mM Ca²⁺. The oxidation of succinate is only affected marginally by chlorotetracycline plus Ca²⁺. The inhibition of NADH oxidation and the fluorescence of CTC are well correlated. Mn²⁺ is the only other cation which shows an (increased) inhibition in the presence of chlorotetracycline. The inhibition by Ca²⁺ and chlorotetracycline disappears at acid pH, and the pH optimum in their presence is 6.4. The inhibition caused by other lipid-soluble Ca²⁺-chelators is not reversible or is enhanced by the addition of excess Ca²⁺. In contrast, inhibition caused by relatively water-soluble chelators is completely reversed by added Ca²⁺. It is suggested that a neutral 1:2 complex is formed between Ca²⁺ and chlorotetracycline which can substitute for Ca²⁺ bound at sites in the lipophilic phase of the inner mitochondrial membrane, which are essential for the activity of the external NADH dehydrogenase.