Control of cocklebur seed germination by nitrogenous compounds : Nitrite, nitrate, hydroxylamine, thiourea, azide and cyanide

Germination of non-dormant upper cocklebur (Xanthium pinsylvanicumWallr.) seeds was stimulated by not only CS(NH₂)₂ but also NH₂OH,KCN and NaN₃. This stimulation was not via the enhancement ofaerobic C₂H₄ production. NH₂OH, KCN and NaN₃ in certain concentrationspromoted the initial growth of axial and/or cotyledonary parts,but the degree of growth promotion by NH₂OH, NaN₃ and KCN wasslight compared with that by CS(NH₂)₂. As in the case of CS(NH₂)₂,however, the germinationstimulating effect of NH₂OH disappearedrapidly as the preceding imbibition period was prolonged. Incontrast, KCN and NaN₃ were still effective in stimulating thegermination of aged seeds maintained on a water substratum,as previously seen with anaerobiosis. Anaerobic induction wasenhanced not only by NaN₃ and KCN but also by NH₂OH, KNO₃, KNO₂CO(NH₂)₂ and CS(NH₂)₂ applied during the anaerobic treatment,but without causing an increase in anaerobic production of C₂H₄.Furthermore, KCN and NaN₃, given prior to the anaerobic treatmentacted additively with anaerobic induction. The germination-stimulatingactions of nitrogenous compounds are discussed in comparisonwith those of C₂H₄ and anaerobiosis. (Received May 6, 1978; )     

Poly(adenosine diphosphate ribose) polymerase activity in neuronal and glial nuclei from bovine cerebrum

Two different preparations isolated from beef cerebrum have been used to compare the polyadenosine diphosphate ribose (polyADPR) polymerase activities in neuronal and glial nuclei: (1) nuclear suspensions (with or without DNase I treatment), and (2) 1 M NaCl nuclear extracts (soluble enzyme). The DNAse I treatment of nuclei and the solubilization of polyADPR polymerase by 1 M NaCl enhances the polyADPR polymerase activity. The polyADPR polymerase activity is similar in neuronal and glial nuclear suspensions, while the neuronal soluble enzyme activity is significantly higher than that of the glial soluble enzyme. Evidence is presented that the difference in soluble enzyme activities is not due to the effects of DNA or degrading enzymes. Some activating factor(s) seem to be present in neuronal soluble extracts, while both inhibiting and activating factor(s) seem to be present in glial soluble extracts.     

Genetic differentiation between two types of dark chub,Zacco temmincki,in Japan

Two types of the dark chub,Zacco temmincki, collected from 10 river systems in Japan were genetically characterized at 27 protein coding loci using starch-gel electrophoresis. They were fixed for different alleles at 13 loci. No hybrid individuals were observed, even in specimens collected in stations where both types appear sympatrically, indicating that each type of the dark chub represents a distinct species.     

Effect of 24,25-dihydroxyvitamin D3 in osteoclasts.

Previous results demonstrated that the administration of pharmacological doses of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) to animals reduces bone resorption and increases bone volume with a decrease in osteoclast number. In order to clarify whether 24,25(OH)2D3 has an effect to inhibit osteoclastic bone resorption, the effect of 24,25(OH)2D3 on the formation and function of osteoclastic cells was examined in vitro. Treatment of hemopoietic blast cells, which are progenitors of osteoclasts, with parathyroid hormone (PTH) or 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) stimulated the formation of osteoclast-like multinucleated cells in a dose-dependent manner. Although 24,25(OH)2D3 in itself had little effect on osteoclast-like multinucleated cells formation, it inhibited the stimulatory effect of PTH on the formation of osteoclastic cells. In addition, 24,25(OH)2D3 also inhibited the stimulation of resorption pit formation by osteoclasts under stimulation with PTH. In contrast, 1,25(OH)2D3 stimulated the formation and function of osteoclastic cells even at low concentrations, and the effect was additive to PTH. These results could not be explained by either an agonistic or antagonistic effect of 24,25(OH)2D3 on 1,25(OH)2D3, and are consistent with the assumption that 24,25(OH)2D3 has a unique inhibitory effect on the formation and function of osteoclasts. Because 24,25(OH)2D3 is shown to stimulate the degradation of 1,25(OH)2D3 and because the formation of 24,25(OH)2D3 is stimulated by 1,25(OH)2D3 not only in the kidney but also in many of its target tissues, including bone, the inhibitory effect of 24,25(OH)2D3 on osteoclastic bone resorption may play a role in the local modulation of the actions of osteotropic hormones in bone.     

Hydrophobic residues 382-386 of antithrombin III, Ala-Ala-Ala-Ser-Thr, serve as the epitope for an antibody which facilitates hydrolysis of the inhibitor by thrombin.

In the presence of a monoclonal antibody raised against the human thrombin-antithrombin III complex, the reaction between thrombin and antithrombin III proceeded to form preferentially a two-chain form of the inhibitor rather than to follow the major pathway of stable acyl complex formation. We thus propose the term "switching antibody" for an antibody that switches the enzyme-inhibitor reaction (Asakura, S., Matsuda, M., Yoshida, N., Terukina, S., and Kihara, H. (1989) J. Biol. Chem. 264, 13736-13739). By analyzing a CNBr fragment of the thrombin-antithrombin III complex that reacts with the antibody we localized the epitope for the antibody to a strongly hydrophobic residue 382-386 peptide segment, Ala-Ala-Ala-Ser-Thr, of the inhibitor, which is also contiguous with a hydrophobic amino acid Ala at its carboxyl terminus. This particular region should be cryptic in nascent antithrombin III, but could have been exposed to provide the reactive site for the antibody at an early stage of the reaction. Thereby a conformational change may have been induced at or near the reactive site of the complex, facilitating hydrolysis of the inhibitor by the enzyme. Interestingly, this hydrophobic region is highly conserved among members of the serpin family.     

A new acid carboxypeptidase,O-1, fromAspergillus oryzae

A new acid carboxypeptidase was purified fromAspergillus oryzae grown on solid bran culture medium. The purified enzyme was found to be homogeneous by disc gel electrophoresis at pH 9.4 and isoelectric focusing. The enzyme was termedA. oryzae acid carboxypeptidase O-1 with isoelectric point 4.08. The substrate specificity of the new enzyme was investigated with proangiotensin, angiotensin, and bradykinin. Even when the proline was present at the penultimate position of the peptide, the enzyme rapidly hydrolyzed the carboxyterminal Pro-X (X=amino acid) peptide bond. TheK _m andk _cat values for angiotension (–Pro⁷–Phe⁸) at pH 3.7 and 30°C were 0.2 mM and 1.7 sec^–1, respectively.     

Soluble and bound forms of intracellular acid carboxypeptidase inAspergillus saitoi

The enzymological, physical, and immunological properties of soluble and bound forms of intracellular acid carboxypeptidase isolated from fresh mycelia ofAspergillus saitoi are reported. In the broken mycelia, about 60% of the total activity was found in the 2,000×g precipitate, with most of the remainder in the 100,000×g supernantant. The highly purified enzymes, I_a and I_b, from the 100,000×g supernatant were found to be homogeneous by such criteria as disc gel electrophoresis at pH 9.4 The bound enzyme, II, was solubilized from the 2,000×g precipitate by self-digestion at pH 6.4 and was highly purified by chromotography. The two forms of intracellular enzymes, the soluble enzymes (I_a and I_b) from the 100,00×g supernatant and the solubilized enzyme (II) from the 2,000×g precipitate, were closely related to, but not completely identical with, the extracellular acid carboxypeptidase.     

Poly(ADPRibose) levels as a function of chick limb mesenchymal cell development as studied in vitro and in vivo.

NAD is converted into a chromatin-bound polymer, poly(ADPribose), with the excision of nicotinamide. In intact cells, the incorporation of labeled adenine, through NAD, into poly(ADPribose) has been correlated with the commitment and/or initial phenotypic expression of chick limb mesenchymal cells. Using an assay for chemical quantities of poly(ADPribose), we report here measurements of poly(ADPribose) during limb development in situ and during limb mesenchymal cell commitment and expressional events in cell culture. Substantial changes in the levels of poly(ADPribose) are observed during early phases of limb cell development either in situ (embryonic stages 22 to 26) or in culture (Days 1 to 4); during this time, we observed a threefold decrease in poly(ADPribose) per unit DNA (21 to 7 nmoles/mg DNA), as compared to relatively minor changes of 10 to 20% during later expressional events especially related to muscle development. These observations establish a correlation between cellular poly(ADPribose) levels and the early phases of chick limb mesenchymal cell differentiation and development.     

Purification and characterization of cytosol phosphoenolpyruvate carboxykinase from bullfrog (Rana catesbeiana) liver.

Cytosol PEP carboxykinase has been purified to electrophoretic homogeneity from bullfrog liver homogenate. The enzyme is a single polypeptide chain with a molecular weight of approximately 72,000-75,000. The purified enzyme catalyzed oxaloacetate decarboxylation (nucleoside triphosphate-supported), phosphoenolpyruvate carboxylation, and an exchange reaction between oxaloacetate and [14C]HCO3-in the presence of ITP or CTP. Manganese is absolutely required for the enzyme-catalyzed phosphoenolpyruvate carboxylation, whereas it can be replaced by Mg2+ for the oxaloacetate decarboxylation and the exchange reaction. The optimal pH of each reaction is dependent on the divalent metal ion used. The dependence of the enzyme activity on Mn2+ is markedly different in the phosphoenolpyuvate carboxylation and the oxaloacetate decarboxylation reactions.