Nucleotide sequence of a cloned woodchuck hepatitis virus genome: evolutional relationship between hepadnaviruses.

We have determined the complete nucleotide sequence of a cloned DNA of woodchuck hepatitis virus (WHV), the most oncogenic virus among hepadnaviruses. The genome, designated WHV2, is 3,320 base pairs long and contains four major open reading frames (ORFs) coded on the same strand of nucleotide sequence as in the human hepatitis B virus (HBV) genome. Comparison of the nucleotide sequence and amino acid sequences deduced from it among the genomes of various hepadnaviruses demonstrates that each protein shows an intrinsic property in conserving its amino acid sequence. A parameter, the ratio of the number of triplets with one-letter change but no amino acid substitution to the total number of triplets in which one-letter change occurred, was introduced to measure the intrinsic properties quantitatively. For each ORF, the parameter gave characteristic values in all combinations. Therefore, the relative evolutional distance between these hepadnaviruses can be measured by the amino acid substitution rate of any ORF. These comparisons suggest that (i) the difference between two WHV clones, WHV1 and WHV2, corresponds to that among clones of a HBV subtype, HBVadr, and (ii) WHV and ground squirrel hepatitis virus can be categorized in a way similar to the subgroups of HBV.     

Hypermotility induced by vasoactive intestinal peptide in the rat: its reciprocal action to cholecystokinin octapeptide

Intracerebroventricular administration of vasoactive intestinal peptide (VIP) shortened the duration of pentobarbital-induced sleep and produced significant hypermotility in the rat. Although hypermotility induced by methamphetamine was not potentiated by central administration of VIP, L-DOPA-induced hypermotility in pargyline-pretreated rats was markedly enhanced by VIP and this hypermotility was suppressed by simultaneous administration of cholecystokinin octapeptide (CCK-8) in a dose-related manner. Apomorphine-induced hypermotility was also potentiated by VIP. These results suggest that VIP may stimulate postsynaptic dopaminergic receptor, causing an increase in motility, and that a possible reciprocal interaction exists between VIP and CCK-8.     

On the oscillatory phenomenon in an oil/water interface

A simple theoretical model is presented for simulating the self-sustained oscillations of electric potential and pH at an oil/water interface appearing in a two-phase system composed of 2-nitropropane solution containing picrate acid and an aqueous solution of cetyltrimethylammonium bromide. In the present model, a well-known condition necessary for the occurrence of self-sustained oscillations, i.e., the presence of a positive feedback process far from equilibrium, is taken into account in a set of kinetic equations to describe simplified characters of the following two processes: (i) a cooperative formation of ion pair complexes at the interface, and (ii) supply of picrate anions and cetyltrimethylammonium cations to the interface accompanied by release of ion pair complexes to the organic phase. The numerical solutions of the present equations are shown to reproduce fairly well the characteristic properties of the oscillation of electric potential and pH such as wave forms and frequencies.     

Nucleotide sequence analysis of DNA replication origins of the small Bacillus bacteriophages: evolutionary relationships

The ends of the small Bacillus phage genomes serve as origins and termini of their DNA replication. We have determined nucleotide sequences at the termini of four different phage DNAs and compared them with those of phi 29 DNA which has been described previously. A high degree of homology was found at the extreme ends of DNAs from phi 29, phi 15 (group A), M2Y and Nf (group B). 17 bp at the far left of the DNAs are identical. A highly conserved dodecanucleotide sequence, CCATTTCCCCAT, was also found in the righthand terminus of all these phage DNAs, at positions 27-38 from the end. Nucleotide sequences of phage GA-1 are not very similar to those of the other phages. Examination of the 5'-terminal and 3'-terminal sequences of all the phages suggests that stable 'panhandle' structures are unlikely to be formed via base pairing of both ends. However, thermodynamically more stable panhandle structures might be formed by displaced single-stranded DNA, although this requires rather large loops.     

Respiration and avoidance reaction of a cyprinid fishPseudogobio esocinus under hypoxia

A cyprinid fish,Pseudogobio esocinus showed gradual bradycardia at oxygen saturation (%) of less than 29.7±4.6 (1.89±0.29 ml/l of oxygen concentration), surfacing at 14.7±1.3 (0.94±0.09ml/l), drastic decrease of oxygen consumption at less than 14.2±0.8 (0.91 ±0.06ml/l) and asphyxia at 9.7±1.4 (0.62±0.09ml/l). The fish avoided water having low oxygen saturation of less than 54.0± 5.4 (3.38±0.30ml/l), and markedly at less than 26.2±3.4 (1.62±0.16 ml/l).     

Guanidoacetate methyltransferase from rat liver: Purification,properties, and evidence for the involvement of sulfhydryl groups for activity

Guanidoacetate methyltransferase (EC 2.1.1.2) has been purified about 800-fold from rat liver. The purified preparation shows a single protein band on polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. The molecular weight of the enzyme is estimated to be 25,000 and 26,000 by Sephadex gel molecular-exclusion chromatography and by electrophoresis in polyacrylamide gradient gel, respectively. The sodium dodecyl sulfate-denatured enzyme also has a molecular weight of 26,000; thus, the enzyme is a monomeric protein. Guanidoacetate methyltransferase as isolated is catalytically inactive, but is readily reactivated by incubation with a thiol. The reactivated enzyme, which contains 3 mol of sulfhydryl groups/mol of enzyme, is again inactivated by oxidized glutathione. This inactivation is accompanied by the disappearance of two sulfhydryl residues. The relationship between the loss of enzyme activity and the number of residues disappeared indicates that the integrity of these sulfhydryl residues is critical for activity. The oxidized enzyme fails to bind the substrate S-adenosylmethionine as evidenced by the equilibrium dialysis study. Alkylation of the nonoxidizable sulfhydryl by N-ethylmaleimide shows that this residue is also essential for activity. UV absorption, fluorescence, and CD spectra show no difference between the reduced and oxidized enzymes, but the former is more susceptible to proteolytic attack by trypsin. The enzyme has an isoelectric pH of 5.3, and is most active at pH 9.0. From the CD spectrum, an α helix content of 15% is calculated. The K_m values for guanidoacetate and S-adenosylmethionine are 97.5 and 6.73 μm, respectively, at pH 8.0 and 37 °C.     

Cytochemical glucose-6-phosphatase activity in the cells of mouse pancreas and submandibular gland

Ultrastructural localization of glucose-6-phosphatase activity was studied in the cells of the pancreas and submandibular gland of the mouse using a incubation medium modified from that of Wachstein & Meisel (1956). In pancreatic acinar cells, the reaction product for the enzyme activity was not found even after 90 min of incubation with three changes of the medium. However, the reaction product was localized in the endoplasmic reticulum and nuclear envelope of all other cell types composing the pancreas and submandibular gland. The reaction product appeared in moderate to abundant amounts in acinar cells and striated duct cells of the submandibular gland, and in the B cells, A and D cells of the pancreatic islet, but it was scarce in other cell types.     

Measurement of turbulence intensity in the center of the canine ascending aorta with a hot-film anemometer

The blood flow velocity near the central axis of the canine ascending aorta was measured with a hot-film anemometer. The cardiac output and the heart rate were controlled at will by means of an extracorporeal circulation and by atrial pacing. The turbulent component of the blood flow velocity was calculated using an ensemble average technique. Ensemble average turbulent intensity was also calculated to show the time course of turbulence in the aorta. The ratio of the mean turbulence intensity to the time mean sectional average velocity in the aorta was constant in most animals regardless of the changes in fluid mechanical parameters. The correlation between the frequency parameter and the relative mean turbulence intensity was weakly positive. The power spectrum of the turbulence was also calculated.