Domains required for nucleic acid binding activities in chloroplast ribonucleoproteins

Five ribonucleoproteins (or RNA-binding proteins) from tobacco chloroplasts have been identified to date; each of these contains an acidic N-terminal domain (24-64 amino acids) and two conserved RNA-binding domains (82-83 amino acids). All five ribonucleoproteins can bind to ssDNA and dsDNA but show high specificity for poly(G) and poly(U). Here we present the nucleic acid binding activity of each domain using a series of deletion mutant proteins made in vitro from the chloroplast 29 kDa ribonucleoproteins. The acidic domain does not have a positive effect on binding activities and proteins lacking this domain show higher affinities for nucleic acids than the wild-type proteins. Mutant proteins containing single RNA-binding domains can bind to poly(G) and poly(U), though with lower affinities than proteins containing two RNA-binding domains. The spacer region (11-37 amino acids) between the two RNA-binding domains does not interact with poly(G) or poly(U) by itself, but is required for the additive activity of the two RNA-binding domains. Proteins consisting of two RNA-binding domains but lacking the spacer have the same activity as those containing only one RNA-binding domain. Possible roles for each domain in chloroplast ribonucleoproteins are discussed.

Electron microscopical demonstration of horseradish peroxidase by use of tetramethylbenzidine as chromogen and sodium tungstate as stabilizer (TMB-ST method): a tracing method with high sensitivity and well preserved ultrastructural tissue

Until now methods using tetramethylbenzidine (TMB) for electron microscopy (TMB-EM methods) are all unable to provide a maximum demonstration of transported horseradish peroxidase (HRP) while maintaining good ultrastructural tissue preservation. In order to solve this problem, we have attempted to adapt a newly developed, highly sensitive TMB method using sodium tungstate (ST) as the stabilizer (TMB-ST method) for HRP electron microscopic retrograde and anterograde fiber tracing. The present study shows that the TMB-ST method combined with diaminobenzidine-cobalt (DAB-Co) is more sensitive than existing TMB-EM methods and that ultrastructural details are well preserved with this combined method. The resultant reaction product complex after osmication is stable and is observed as characteristic crystal-like structures which are extremely electron dense and often aggregated into clumps. In contrast, the TMB-ST method without the DAB-Co step frequently produces a moderate electron-dense reaction product. Therefore, we recommend the TMB-ST method combined with DAB-Co for HRP electron microscopy.

[A mid-infrared spectra study of a series of benzocrown ether and macrocyclic polyether diester]

With a Nicolet 20 SX B Fourier Transform infrared spectrometer, the mid-infrared spectra in region of 4000-400 cm-1 were observed for a series of benzocrown ether and macrocyclic polyether diester. A difference in the wavelength of absorption of the ether bond was found between benzocrown ether and macrocyclic polyether diester. The wavelength of absorption of the ether bond of the compounds I-IV moved down about 25 cm-1, as compared with that of the compounds V-IX.

Molecular cytogenetic study of short arm aberrations in human D, G group chromosomes

Six cases of Dp+/Gp+, 10 cases of D/G translocation, 1 case of supernumerary marker chromosome, and 1 case of Yqs were studied using molecular and cytogenetic techniques. The Ag-NOR frequencies of the Dp+ and Gp+ groups were found to be higher than those of normal controls, while their satellite association frequencies were lower. Autoradiographic silver grains were not significantly distributed along the p+ part of the marker chromosome as revealed by chromosomal in situ hybridization using an rRNA probe. This result differs from our previous report. It is suggested that there might be different mechanisms for the formation of p+ on acrocentric chromosomes. D/G translocation cases were found to have lost their NOR. A study of supernumerary marker chromosomes and Yqs cases suggested that the marker chromosome and Yqs exerted no phenotypic effect. The mechanism of their formation is discussed.

[Permeability of 5 methemoglobin formers through red cell membrane]

By measuring the methemoglobin formation, the permeabilities of some cyanide antidotes passing through mouse erythrocyte membrane were studied. K3Fe(CN)6(0.1 mol/L) did not permeate the red cell and no methemoglobin formed. To the red cell suspension, adding PAPP 0.07 mmol/L, an useful cyanide antidote, no methemoglobin was found. On the contrary, PHAPP, the metabolite of PAPP, transported into the cell readily and reacted with hemoglobin to form methemoglobin quickly. DMAP and NaNO2 passed through the red cell membrane easily. With comparable amount of methemoglobin formation, the concentration of NaNO2 was about 200 times as much as that of DMAP. A comparison of the anticyanide potency of DMAP and NaNO2, the permeability rate constant, the half time and activation energy were measured as: 0.217 and 0.0506/min; 3.2 and 13.7 min; 17.1 and 50.2 kJ/mol, respectively. Owing to its ready permeability and formation of methemoglobin, DMAP is a better antidote than NaNO2 against cyanide poisoning.

The diagnostic value of a hepatoma-specific band of serum gamma-glutamyl transferase

Using a vertical slab electrophoretic apparatus loaded with polyacrylamide stage gel plate, we observed a total of II bands of gamma-glutamyl transferase (EC 2.3.2.2,GGT) on a gel plate and designated these GGT I-XI by order of distance beginning at the positive pole. Positive GGT II was found in 81 (90%) of 90 cases of primary hepatic carcinoma (PHC), in 9(90%) of 10 cases of secondary hepatic carcinoma (SHC), and in only 4 (3.1%) of a total of 128 cases of acute and chronic liver disease. There was one case with positive GGT II among 45 cases of cancer of ampulla of Vater, but the possibility of hepatic metastasis could not be excluded. No GGT II was found in a total of 250 healthy persons and 21 pregnant women. PHC patients with negative alpha-fetoprotein (AFP) had a positive GGT II rate of 84.6%, whereas in those with negative GGT II the positive rate for AFP was only 44.4%.