Low-pressure microwave-induced helium plasma emission spectrometry: Vaporization characteristics of metal chlorides,nitrates, and sulfates

A low-pressure microwave-induced helium plasma serves as an excitation source for metal chlorides, nitrates, and sulfates vaporized from a filament, resulting in fractional vaporization and differential sensitivities of detection of the elements depending on the vapor pressures of their salts. The shapes of the single emission peaks, which are simple in the presence of potassium chloride, become complex and may double in number.     

1,25-Dihydroxyvitamin D stimulates sodium-dependent phosphate transport by renal outer cortical brush-border membrane vesicles by directly affecting membrane fluidity

We examined the effects of several forms of vitamin D added to renal brush-border membrane suspensions on phosphate and glucose transport and on membrane fluidity. The 1,25-D stimulated and the other vitamin D decreased phosphate uptake. In contrast, glucose uptake was not affected by the treatment of vitamin D. The 1,25-D resulted in a significant shift of the lower transition temperature in Arrhenius plots for phosphate, but not for glucose uptakes, from 15 degrees C to 11.5 degrees C. These data indicate that the 1,25-D may alter membrane fluidity, limited to the phosphate transporter, thus affecting the phosphate uptake.     

Structure and antitumor activity of an alkali-soluble polysaccharide from Cordyceps ophioglossoides

A water-insoluble extracellular glucan (CO-1) was isolated from the precipitate formed on incubation of the culture filtrate of Cordyceps ophioglossoides at 37 degrees for 19 h. CO-1 was homogeneous as judged by h.p.l.c., electrophoresis, and ultracentrifugation, and the average molecular weight was determined by h.p.l.c. to be 632,000. The 1H- and 13C-n.m.r. and the i.r. spectra indicated that the glucosidic linkages in CO-1 were beta. From the results of methylation analysis, Smith degradation, n.m.r. studies, and enzymic hydrolysis, it was concluded that CO-1 is composed of a backbone of (1----3)-linked beta-D-glucopyranosyl residues with a beta-D-glucopyranosyl group attached to O-6 of every second D-glucopyranosyl residue of the backbone. CO-1 strongly inhibited the growth of Sarcoma 180 solid-type tumor. CO-1 polyalcohol, which was prepared by Smith degradation of CO-1, exhibited more-potent antitumor activity than CO-1. The absorption maximum of Congo Red shifted significantly in the presence of CO-1.     

Studies on the biological activity of an insulin-stimulating peptide from a tryptic digest of bovine serum albumin

Summary A two-chain polypeptide, which corresponds to amino acid residues 115–143 and 144–184(185) of bovine serum albumin, connected to each other by a disulfide bridge, potentiated the effects of insulin on glucose transport and glucose metabolism in isolated rat adipocytes. Although the peptide alone had little activity, it shifted the concentration-response curves of insulin-stimulated D-[I-¹⁴C]glucose oxidation, 2-deoxyglucose transport, and lipid synthesis from D-[U-¹⁴C]glucose to lower insulin concentrations. It also increased the maximal responses of these parameters to insulin. However, it did not affect insulin binding to adipocytes. The peptide protected insulin considerably from degradation, but this effect alone cannot account for its effect in increasing the maximal responses to the hormone, and even when degradation of a submaximal concentration of insulin was suppressed by bacitracin, the peptide still had an enhancing effect. These results suggest not only that the peptide influences a step distal to receptor-mediated insulin binding but also that inhibition of insulin degradation alone cannot explain its total effect.The peptide lost its insulin-stimulating activity completely when it was further digested with V8 or lysinespecific endopeptidase, or when it was reduced and then carboxamidomethylated or oxidized with performic acid. Similar active tryptic fragments were obtained from human and rat albumins.Insulin-stimulating peptides should be useful in studies on the mechanisms of insulin action including both the sensitivities and responsiveness of target cells to the hormone.Abbreviations ISP insulin-stimulating peptide - HEPES N-(2-hydroxyethyl)piperazine-N-2-ethanesulfonic acid - HPLC high-performance liquid chromatography - SDS sodium dodecyl sulfate     

Structure and inherent properties of the bacteriophage lambda head shell. III. Spectroscopic studies on the expansion of the prohead

The head shell of bacteriophage lambda expands by about 20% in diameter when it packages the DNA molecule in vivo. The expansion reaction is essentially a conformational change of the major head protein molecules to a state of lower free energy and can also be triggered in vitro by treatment with 4 M-urea. In order to investigate the conformational change, we have measured the circular dichroism, fluorescence and difference absorption spectra of the lambda head shell before and after the expansion by the treatment with urea. The far-ultraviolet circular dichroism spectra and the fluorescence spectra show that the expansion is not accompanied by a great change in the secondary structure (29% alpha-helix, 23% beta-structure) and the environment (non-polar) of the tryptophan residues of the major head protein molecule. On the other hand, by measurements of the circular dichroism and difference absorption spectra in the near-ultraviolet region as well as by chemical modification experiments with tetranitromethane, we have found that one or two tyrosine residues of the major head protein are transferred from a polar, solvent-exposed to a non-polar, solvent-unexposed environment during the expansion. Judging from these results, the conformational change seems to be mainly intermolecular or interdomainal rather than intradomainal.     

Carbon-cycling changes during regeneration of a decinduous broadleaf forest after clear-cutting II. Aboveground net production

Growth and death rates of aboveground plant parts were measured in a mature forest and four different-aged deciduous broadleaf forests regeneratede after clear-cutting, with special reference to rates for woody parts (stems and branches) of different diameters (ø) in rerms of the pipe model theory (Shinozaki et al., 1964). The total biomass increment of woody parts of trees higher than 1.3 m varied within a range of 2.1-4.6 ton ha^?1 yr^?1, the increase beingdue largely to the growth of canopy trees exposed to direct sunlight. Biomass increments of small (ø<1 cm) and medium (1≤ø<5 cm) woody parts were negligibly small except in the youngest forest, and changes in aboveground woody biomass with forest age after clear-cutting mainly resulted from accumulation of large (5 cm<ø) woody parts of canopy trees. Biomass loss of trees due to death and grazing increased with forest age from 4.0 to 8.3 ton ha^?1 yr^?1. Recovery of leaf and small wood falls was observed at the early stage of regeneration, while large wood falls increased during regeneration. Flower and fruit fall was markedly higher in the mature forest than in the other four forest types. Mortality of woody parts became higher with forest age and was 20, 5.0 and 0.46% yr^?1 for small, medium and large parts, respectively, at the mature stage. Aboveground net production of the forest was in therange 7.6-13.3 ton ha^?1 yr^?1 with the undergrowth vegetation lower than 1.3 m being 0.4-1.4 ton ha^?1 yr^?1. Production recovered rapidly at an early stage of regeneration and was highest in mature forest.     

Unusual Branching in the Seedlings of Lotus japonicus--Gibberellins Reveal the Nitrogen-sensitive Cell Divisions within the Pericycle on Roots

We studied the effects of several plant-growth regulators onthe induction of nodule-like structures on roots of Lotus japonicus,which has been proposed as a candidate for a leguminous plantfor molecular genetic analysis. Contrary to our expectations,the addition of gibberellin A₃ (GA₃) at concentrations of 10^-4M to 10^-4 M resulted in the formation of nodule-like structureson roots when seedlings were plated on nitrogen-free Fahraeusagar medium. GA₄ also induced such outgrowths but was less activethan GA₃. Application of an inhibitor of auxin transport, N-(1-naphthyl)-phthalamicacid (NPA) and of kinetin, which have been reported to inducepseudonodules in other legumes, had no effect on L. japonicus.Microscopic observations showed that GA₃-induced nodule-likestructures were caused by cell divisions within the pericycleon the roots. In addition, the outgrowths elicited by GA₃ couldbe completely suppressed by the addition of 15 mM potassiumnitrate or ammonium nitrate. These results show that the pericyclecells of the roots of L. japonicus are specifically sensitiveto gibberellins and that potential for cell division might bemodulated by nitrogen compounds. We also examined the effectsof ancymidol and uniconazole [S-3307; (E)-1-(4-chIorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol],two synthetic plant-growth retardants. Both compounds at 3 x10^-5 M significantly increased the number of stunted lateralroots. The unusual branching could not be counteracted by theexogenous addition of GA₃ but by 10^-6 M brassinolide. We discussthe physiological role of brassinolide in the initiation oflateral roots. (Received August 4, 1995; Accepted March 11, 1996)     

The Excessive Production of Indole-3-Acetic Acid and Its Significance in Studies of the Biosynthesis of This Regulator of Plant Growth and Development

Because of the importance of indole-3-acetic acid (IAA) in thegrowth and development of plants, extensive studies of the biosynthesisof IAA have been performed during the four decades since thediscovery of IAA as a plant hormone. The pathway for the biosynthesisof IAA in plants remains, however, to be unelucidated, eventhough studies within the past decade have revealed unexpectedaspects of such biosynthesis. By contrast, two pathways to IAAhave been characterized in bacteria at the molecular level:the indole-3-acetamide (IAM) pathway (L-tryptophan     

Peroxyoxalate chemiluminescent assay for oxidase activities based on detecting enzymatically formed hydrogen peroxide

A sensitive peroxyoxalate chemiluminescent (PO-CL) assay for activities of oxidases (uricase, choline oxidase, cholesterol oxidase and xanthine oxidase) which catalyse a formation of hydrogen peroxide was developed using 4,4′-oxalyl-bis[(trifluoromethylsulphonyl)imino]trimethylene-bis(4-methylmorpholinium)trifluoromethanesulphonate as a chemiluminogenic reagent and 2,4,6,8-tetramorpholinopyrimido[5,4-d]pyrimidine as a fluorophore. The standard curve for hydrogen peroxide was linear over the range 1 × 10^?7-1 × 10^?4 mol/L. Relative standard deviations for oxidase assays were 5.1–12.7% (n = 10). Detection limits were 1 × 10^?3 U/mL for uricase, 5 × 10^?4 U/mL for choline oxidase, 5 × 10^?3 U/mL for cholesterol oxidase and 5 × 10^?4 U/mL xanthine oxidase (sample to blank ratio, 3).