Lamina-specific localization of silicon accumulation in two broadleaf tree species

Journal of Plant Research - Silicon (Si) accumulation differs greatly among plant species, as revealed by an increasing number of studies reporting whole-leaf Si concentration for a wide range of...     

Purification, characterization, cDNA cloning and nucleotide sequencing of a cellulase from the yellow-spotted longicorn beetle, Psacothea hilaris.

A cellulase (endo-beta-1,4-glucanase, EC 3.2.1.4) was purified from the gut of larvae of the yellow-spotted longicorn beetle Psacothea hilaris by acetone precipitation and elution from gels after native PAGE and SDS/PAGE with activity staining. The purified protein formed a single band, and the molecular mass was estimated to be 47 kDa. The purified cellulase degraded carboxymethylcellulose (CMC), insoluble cello-oligosaccharide (average degree of polymerization 34) and soluble cello-oligosaccharides longer than cellotriose, but not crystalline cellulose or cellobiose. The specific activity of the cellulase against CMC was 150 micro mol.min-1.(mg protein)-1. TLC analysis showed that the cellulase produces cellotriose and cellobiose from insoluble cello-oligosaccharides. However, a glucose assay linked with glucose oxidase detected a small amount of glucose, with a productivity of 0.072 micro mol.min-1.(mg protein)-1. The optimal pH of P. hilaris cellulase was 5.5, close to the pH in the midgut of P. hilaris larvae. The N-terminal amino-acid sequence of the purified P. hilaris cellulase was determined and a degenerate primer designed, which enabled a 975-bp cDNA clone containing a typical polyadenylation signal to be obtained by PCR and sequencing. The deduced amino-acid sequence of P. hilaris cellulase showed high homology to members of glycosyl hydrolase family 5 subfamily 2, and, in addition, a signature sequence for family 5 was found. Thus, this is the first report of a family 5 cellulase from arthropods.     

Analysis of randomly isolated cDNAs from developing endosperm of rice (Oryza sativa L.): evaluation of expressed sequence tags,and expression levels of mRNAs

Using a cDNA library prepared from poly(A)⁺ RNA from 10-day-old rice endosperm, partial nucleotide sequences of randomly isolated clones were analyzed. A total of 153 (30.6%) out of 500 cDNA clones showed high amino acid identity to previously identified genes. There was significant redundancy in cDNAs encoding prolamine and glutelin. About 21.0% of the cDNA clones were found to code for seed storage protein genes. Consequently, 37 independent genes were identified. Using cDNA clones encoding glutelin, prolamine, seed allergen, -1,4-glucan branching enzyme, glycine-rich RNA binding protein, metallothionein, non-specific lipid-transfer protein and ubiquitin conjugating enzyme the accumulation of mRNA during rice seed development was compared. Genes associated with seed storage protein and starch biosynthesis were expressed according to expected developmental stages. Glycinerich RNA binding protein genes as well as metallothionein-like protein genes were highly expressed in developing seeds, but low in leaves of whole plants.     

Possible involvement of ethylene-activated {beta}-cyanoalanine synthase in the regulation of cocklebur seed germination

A possible involvement of ß-cyanoalanine synthase(CAS: EC 4.4.1.9 [EC] ) in germination processes of seeds was demonstratedusing pre-soaked upper seeds of cocklebur (Xanthium pennsylvanicumWallr.). Pretreatment in anoxia not only with KCN but also cysteine,as the substrates for CAS, stimulated the subsequent germinationof cocklebur seeds in air. However, the effect of cysteine wasmanifested even in air when applied together with C₂H₄, andits effect was further enhanced in combination with KCN. Thegermination-stimulating effect of KCN was intensified by C₂H₄only when 0₂ was present. In contrast, serine, another substrateof CAS, was effective in air only when combined with C₂H₄ and/orKCN. The addition of cysteine greatly reduced the cyanogenicglycoside content of seeds, but increased HCN evolution. Onthe other hand, glutathione did not have any effect on cockleburseed germination, HCN evolution or bound cyanogen content, suggestingthat cysteine is not acting as a reducing reagent. It is suggestedthat CAS regulates the process of cocklebur seed germinationby the dual action of enlarging the pool of amino acids andsupplying sulphydryl bases, the latter being more determinatelyimportant. Serine is effective only via the former action, whilecysteine would act via both. Key words: Cyanide, cyanogenic glycoside, ß-cyanoalanine synthase, seed germination, Xanthium pennsylvanicum     

Relations Between the Extracellular Concentrations of Choline and Acetylcholine in Rat Striatum

Abstract: Changes in extracellular levels of acetylcholine (ACh) and choline (Ch) in the striatum of rats were examined by in vivo microdialysis after intraperitoneal injections of drugs. A dopamine D₂ antagonist, sulpiride (20 mg/kg), and a muscarinic antagonist, atropine (3.5 mg/kg), increased ACh levels and decreased Ch levels. On the contrary, the D₂ agonist (±)-2-( N -phenylethyl- N -propyl)amino-5-hydroxytetralin (N-434; 5 mg/kg) and an anesthetic, pentobarbital (50 mg/kg), decreased ACh levels and increased Ch levels. Perfusion of 10 µ M hemicholinium-3 (HC-3), a Ch uptake inhibitor, through the striatum induced a complete inhibition of ACh release and increased Ch levels in all drug-treated groups. The degree of relative increase in the level of Ch induced by HC-3 differed among the drug-pretreated groups; compared with the control group, the relative increase was larger in the sulpiride- and atropine-treated groups and smaller in the N-434 and pentobarbital-treated groups. Thus, we demonstrated reciprocal relations between extracellular concentrations of Ch and ACh after treatments by drugs. The data suggest that in the striatum, which is rich in cholinergic innervation, the extracellular Ch concentration is to a large extent determined by activity of the cholinergic transmission reflected in high-affinity choline uptake.     

Growth and muscle protein turnover in the chick

The growth rates of young chicks were varied from 0 to 10% per day by manipulation of the adequacy of the amino acid and energy supply. The rates of protein synthesis in the white breast (pectoralis thoracica) muscle and the dark leg (gastrocnemius and peronaeus longus) muscles were estimated by feeding l-[U-¹⁴C]tyrosine in amino acid/agar-gel diets (`dietary infusion'). This treatment rapidly and consistently produced an isotopic equilibrium in the expired CO₂ and in the free tyrosine of plasma and the muscles. Wholebody protein synthesis in 2-week-old chicks was estimated from the tyrosine flux and was 6.4g/day per 100g body wt. In 1-week-old chicks the rate of protein synthesis was more rapid in the breast muscles than in the leg muscles, but decreased until the rates were similar in 2-week-old birds. Synthesis was also more rapid in fast-growing Rock Cornish broilers than in medium-slow-growing New Hampshire×Single Comb White Leghorn chicks. No or barely significant decrease in the high rates of protein synthesis, in the protein/RNA ratio and in the activity of RNA for protein synthesis occurred in non- or slow-growing chicks fed on diets deficient in lysine, total nitrogen or energy. Thus the machinery of protein synthesis in the young chick seems to be relatively insensitive to dietary manipulation. In the leg muscles, there was a small but significant correlation between the fractional rate of growth and protein synthesis. A decrease in the fractional rate of degradation, however, appeared to account for much of the accumulation of muscle protein in rapidly growing birds. In addition, the rapid accumulation of breast-muscle protein in rapidly growing chicks appeared to be achieved almost entirely by a marked decrease in the fractional rate of degradation.     

Mammalian collagenase increases in early alcoholic liver disease and decreases with cirrhosis

To determine if alterations in collagen degradation may contribute to the pathogenesis of fibrosis and cirrhosis, we studied the hepatic collagenase activity of 20 baboons given alcohol containing diets or control diets under carefully controlled experimental conditions. We also studied 28 patients whose livers were biopsied for diagnostic purposes. Hepatic collagenase activity was significantly increased in baboons with fatty liver compared to levels in normal, control fed animals [(1.98 +/- 0.19 vs 1.20 +/- 0.08 units (microgram collagen digested/hour/mg liver protein) +/- S.E.M., p less than 0.001)]. The increase in hepatic collagenase activity persisted at the stage of fibrosis when compared to the activity in control baboons (2.16 +/- 0.07 vs 1.20 +/- 0.08 units +/- S.E.M., p less than 0.001). A single cirrhotic baboon available for study had an hepatic collagenase activity of 1.58 units. Patients with hepatic fibrosis had significantly higher hepatic collagenase activity than those with fatty livers [(9.12 +/- 0.94 (n =14) vs 4.52 +/- 0.54 (n = 7) units +/- S.E.M., p less than 0.001)]. However, in the group with cirrhosis, hepatic collagenase was lower [(3.92 +/- 0.61 (n = 7) units +/- S.E.M., p less than 0.001)] than in the group with fibrosis. Our findings suggest that the development of cirrhosis is coincident with, or favored by a failure of hepatic collagen degradative enzymes to keep pace with hepatic collagen synthesis.     

Non-random distribution of transduction termini in transductants from the integrated R plasmid, R100-1

Summary Tra ⁺and tra ^–derivatives of drug resistance plasmid, R100-1, were isolated by phage P1 from an Hfr donor with integrated R100-1 and then analyzed by complementation tests with tra ^–point mutants of Flac. Tra ⁺derivatives of R100-1 carrying tetracycline resistance alone and those carrying all six drug-resistance genes could support transfer of tra ^–point mutants of Flac except Flac traJ, whereas all of tra ^–derivatives of R100-1 failed to complement any one of tra ^–point mutants of Flac. This suggests that these tra ^–derivatives of R100-1 carrying tetracycline resistance gene are deleted for all the transfer genes impaired in the Flac point mutants tested. We assume a hot point, probably a specific base sequence similar to an IS element, at the left of the tetracycline gene (Fig. 1) becomes a transduction terminus in transduction of the integrated R100-1 by phage P1. Complementation analysis of tra ^–derivatives carrying five resistance genes except the tetracycline gene led us to a supposition that a gene(s), probably analogous to traJ of the F plasmid, is located on R100-1 near the tetracycline gene which plays an important regulatory role for self-transfer as well as for the complementation of tra ^–Flac mutants.