Genotype dependent variation in mycorrhizal colonization and response to inoculation of pearl millet

Summary Genotypes of pearl millet (Pennisetum americanum L. Leeke) were examined for differences in vesicular-arbuscular mycorrhizal (VAM) colonization and response to inoculation. For thirty genotypes tested across three field locations there was a range of mycorrhizal colonization intensity between 25 and 56%. In another experiment with two male-sterile lines, restorer lines and their derived crosses, grown in pots filled with non-sterilized soil there were significant differences between genotypes for colonization by mycorrhiza. This showed hostgenotype dependence for mycorrhizal colonization.Root growth rates, mycorrhizal root length, percentage root colonization and plant growth and P uptake were studied in ten genotypes. A set of 3 genotypes with similar root lengths varied significantly with regard to mycorrhizal root length and the percentage colonization. This supports the suggestion that VAM colonization and spread is dependent on the host genotype. The growth responses differed significantly between the genotypes and they also differed in their responses to P uptake and VAM inoculation. The utility of host-genotype dependent differences in VAM symbiosis in plant breeding is discussed.Journal Article No. 453     

Monoclonal antibodies to mitochondrial coupling factor B

Two monoclonal antibodies (MAb I and IV) have been prepared which showed high and specific reactions towards bovine heart mitochondrial coupling factor B (FB). Both have been identified as sub-type IgG1 of mouse immunoglobulins. MAb I reacts with purified and functionally active FB, alkylated or oxidized forms of FB and even with peptides formed on digestion of FB with trypsin. When used together, MAb I and IV reacted with FB in immunoblots of normal and urea treated samples of mitochondria, submitochondrial particles, ammonia-EDTA extracted particles, and H+-ATPase. Both MAbs inhibited FB-stimulated ATP-dependent reverse electron flow activity when FB was incubated with the antibody either before or after its addition to FB-deficient AE-particles. Reactivity of MAb I towards FB declined upon exposure of FB to guanidine HC1 while reactivity of MAb IV remained unaltered.     

Innervation of the limb accessory flexor muscle in several decapod crustaceans. II. Electrophysiology

The innervation of the distal and proximal heads of the accessory flexor muscle in three portunid crabs and two non-portunid decapods was studied electrophysiologically. In all species studied, the proximal head received only the two previously reported accessory flexor axons, an excitor and an inhibitor. The same two axons also innervated the distal head in all species, but in the portunids the distal head also received excitation from at least three, and probably sometimes four, of the main flexor excitor efferents. The accessory inhibitor exerted very strong effects in the tonic muscle fibers found in the proximal head and in the most proximal bundle of the distal head. The newly described inhibitory and excitatory distributions may have important implications for locomotory behavior.     

Prediction and comparison of the secondary structure of legume lectins

Secondary structure prediction for the 4 legume lectins: Concanavalin A, soybean agglutinin, favabean lectin and lentil lectin, was done by the method of Chou and Fasman. This prediction shows that these four lectins fall into a structurally distinct class of proteins, containing high amounts of β-sheet and β-turns. There is a notable similarity in the gross structure of these proteins; all four of them contain about 40–50% of β-sheet, 35–45 % β-turn and 0–10% of α-helix. When the secondary structure of corresponding residues in each pair of these lectins was compared, there was a striking similarity in the Concanavalin A-soybean agglutinin and favabean lectin-lentil lectin pairs, and considerably less similarity in the other pairs, suggesting that these legume lectins have probably evolved in a divergent manner from a common ancestor. A comparison of the predicted potential β-turn sites also supports the hypothesis of divergent evolution in this class of lectins.     

On control of the function of the sodium-potassium pump in malignant cells

This paper introduces a double-layer enzyme-membrane model representing the Na⁺−K⁺ pump in living cells. We present a mathematical solution to the problem of controlling the sodium flux in malignant cells, where an inhibitor exists in the outer layer of the membrane. We give an algorithm for the numerical resolution of this problem of optimal control with illustrations. Finally, we point out the biological importance of this study.     

Mycobacterium senegalense from bovines in Eastern Nigeria

M ohan , K. 1985. Mycobacterium senegalense from bovines in Eastern Nigeria. Journal of Applied Bacteriology 59 , 277–281.
Detailed characteristics of three mycobacterial strains sharing important properties of Mycobacterium senegalense are described. Their physiological properties were compared with those of a typical M. senegalense strain described by Chamoiseau (1979), six strains of M. senegalense and one typical strain of M. fortuitum from the culture collection of Institute of Microbiology, Rutgers. The three Nigerian strains exhibited minor variations in their physiological properties when compared with other strains of M. senegalense . Unlike the strain of Chamoiseau the Nigerian strains did not utilize benzoate or citrate. The strains were also different from the other six strains of M. senegalense by utilizing trehalose and in failing to produce acid in mannitol. Unlike earlier isolates of M. senegalense the Nigerian strains were not from cases of bovine farcy but from cases with pathological manifestations of pulmonary tuberculosis. They appeared to be intermediate strains between M. senegalense and M. fortuitum . These results raise doubts on the justification for giving specific rank to M. senegalense .     

Variation and inheritance of the arachin polypeptides of groundnut (Arachis hypogaea L.)

Summary Variation in the arachin polypeptides of groundnut genotypes was observed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Three regions could be observed on the electropherogram. Region 1, corresponding to conarachin, did not show any variation; region 2, consisting of arachin acidic subunits, showed variation; region 3, containing the arachin basic subunits, did not show any variation. There are four varietal classes of arachin polypeptide patterns: class A comprised three acidic subunits of arachin of molecular weights 47.5, 45.1 and 42.6 kd and a basic subunit of 21.4 kd; class B, with three acidic subunits of molecular weights 47.5, 45.1 and 41.2 kd and a basic subunit of 21.4 kd; class C of an additive pattern of class A and class B; class D, of two acidic polypeptides of 47.5, 45.1 kd and the basic 21.4 kd subunit. Of the 90 genotypes studied, 73% belong to class A, 15% to class B and 6% each to class C and D. Analysis of F₂ seeds from a cross between class A and class B genotypes showed that the two polypeptides (42.6 kd and 41.2 kd) are coded by nonallelic genes and also revealed that class C and class D patterns arose as a result of hybridisation between class A and class B. A. monticola, the progenitor of A. hypogaea, showed a pattern similar to the additive pattern of class A and class B while some diploid Arachis species had the 41.2 kd polypeptide. Based on arachin polypeptide patterns the probable origin of A. hypogaea has been suggested.     

Nucleotide sequences of transfer RNA genes in the Pisum sativum chloroplast DNA

Summary Eight transfer RNA (tRNA) genes which were previously mapped to five regions of the Pisum sativum (pea) chloroplast DNA (ctDNA) have been sequenced. They have been identified as tRNA^Val(GAC), tRNA^Asn(GUU), tRNA^Arg(ACG), tRNA^Leu(CAA), tRNA^Tyr(GUA), tRNA^Glu(UUC), tRNA^His(GUG), and tRNA^Arg(UCU) by their anticodons and by their similarity to other previously identified tRNA genes from the chloroplast DNAs of higher plants or from E. gracilis. In addition,two other tRNA genes, tRNA^Gly (UCC) and tRNA^Ile(GAU), have been partially sequenced. The tRNA genes are compared to other known chloroplast tRNA genes from higher plants and are found to be 90–100% homologous. In addition there are similarities in the overall arrangement of the individual genes between different plants. The 5 flanking regions and the internal sequences of tRNA genes have been studied for conserved regions and consensus sequences. Two unusual features have been found: there is an apparent intron in the D-loop of the tRNA^Gly(UCC), and the tRNA^Glu(UUC) contains GATTC in its T-loop.     

Prevention of aortic lesions and hyperlipidaemia by alfalfa seed extract in cholesterol fed rabbit

Extract of alfalfa seed (ethanolic 50 % v/v) prevents the development of plaque formation and hyperlipidaemia in cholesterol fed rabbits. It inhibits the elevation of serum total cholesterol, triglycerides, phospholipids, LDL-cholesterol and total cholesterol/phospholipid ratio, while HDL-cholesterol/total cholesterol ratio increases, which is associated with a reduced incidence of atherosclerosis. Further reduction in total cholesterol and phospholipid contents of liver and heart muscle are suggestive of a beneficial role of the seed extract. The possible mechanisms of action are discussed.     

Correlation between nuclear glucocorticoid receptor levels and casein gene expression in murine mammary gland in vitro

The relationship between nuclear binding of glucocorticoid-receptor complex and casein gene expression was studied in organ culture of the whole mammary gland of the mouse. Pyridoxal 5'-phosphate was used as a modulatory agent for measuring nuclear binding of the receptor complex. Addition of 2 mM and 5mM pyridoxal-5'-P in the medium (Waymouth's MB752/1) resulted in 4- and 12-fold increase of its concentration in the glands incubated with insulin, prolactin, and hydrocortisone. Pyridoxal-5'-P also caused a 52% and 92% inhibition of nuclear binding of [3H]dexamethasone in the glands at 2 mM and 5 mM concentration in the presence of the same hormones in the medium. Corresponding to the reduced nuclear binding of the receptor complex casein mRNA levels, measured by a specific cDNA probe was reduced 86% and over 90% in the glands exposed to 2 mM and 5 mM pyridoxal-5'-P, respectively, in presence of insulin, prolactin, and hydrocortisone in the medium. Withdrawal of pyridoxal-5'-P from the medium restored nuclear binding of the receptor complex near the level of control glands incubated only with the hormones. mRNA casein levels also increased in the gland in the pyridoxal-5'-P-free medium containing the same hormones. This indicates that pyridoxal-5'-P does not alter the specific hormone responsiveness of the mammary cells and its action mediated at the level of the glucocorticoid receptor can influence hormone-inducible expression of the casein genes. Thus, glucocorticoid plays a major role in the multiple hormone regulation of the milk protein gene(s). The findings also suggest that the breast tissue concentration of the vitamin B6 derivative may influence the physiology of lactation in nursing mothers.