The Nucleotide Sequence of Human Acylamino Acid-Releasing Enzyme

The nucleotide sequence of a cDNA coding for the human acylaminoacid-releasing enzyme (AARE, also known as acylpeptide hydrolase)[EC 3.4.19.1] subunit has been determined. The amino acid sequenceof human AARE subunit deduced from its cDNA nucleotide sequenceshowed a high degree of identity (91.5%) with both the correspondingproteins from the pig and the rat. The AARE cDNA shows 99.2%identity with a 3.3 kb cDNA transcribed from a locus (DNF15S2)on the short arm of human chromosome 3, whose deletion is associatedwith small cell lung cancer, taking into consideration thatthe sequence of the 3.3-kb cDNA previously reported was causedby misreading.     

Aggressiveness of male mice: Cooperation between cage-mates

Male mice (Mus domesticus) were reared in groups of 2 or 3 males until 13 weeks of age. They then fought each other every third day. Aggressiveness was quantified on the basis of the frequency of aggressive behavior shown by each mouse in each match. The data suggest that there was positive correlation between the levels of aggression of the cage-mates in the 2-male group. Significant correlations also existed between the most doninant and subordinate males and between the secondary and the subordinate males in the 3-male group. The aggressiveness of male mice correlated positively with that of their cage-mates from 65 to 91 days of age but did not correlate with that of the cage-mate living together from 35 to 61 days of age.     

Mercurial-sensitive water transport in barley roots

An isolated barley root was partitioned into the apical and basal part across the partition wall of the double-chamber osmometer. Transroot water movement was induced by subjecting the apical part to a sorbitol solution, while the basal part with the cut end was in artificial pond water. The rate of transroot osmosis was first low but enhanced by two means, infilitration of roots by pressurization and repetition of osmosis. Both effects acted additively. The radial hydraulic conductivity (Lp_r) was calculated by dividing the initial flow rate with the surface area of the apical part of the root, to which sorbitol was applied, and the osmotic gradient between the apical and basal part of the root. Lp_r which was first 0.02–0.04 pm s⁻¹ Pa⁻¹ increased up to 0.25–0.4 pm s⁻¹ Pa⁻¹ after enhancement. Enhancement is assumed to be caused by an increase of the area of the plasma membrane which is avallable to osmotic water movement. The increased Lp_r is in the same order of magnitude as the hydraulic conductivity (Lp) of epidermal and cortical cells of barley roots obtained by Steudie and Jeschke (1983). HgCl₂, a potent inhibitor of water channels, suppressed Lp_r of non-infiltrated and infiltrated roots down to 17% and 8% of control values, respectively. A high sensitivity of Lp_r to HgCl₂ suggests that water channels constitute the most conductive pathway for osmotic radial water movement in barley roots.     

Synonymous substitution rates in Drosophila: Mitochondrial versus nuclear genes

Synonymous substitution rates in mitochondrial and nuclear genes of Drosophila were compared. To make accurate comparisons, we considered the following: (1) relative synonymous rates, which do not require divergence time estimates, should be used; (2) methods estimating divergence should take into account base composition; (3) only very closely related species should be used to avoid effects of saturation; (4) the heterogeneity of rates should be examined. We modified the methods estimating synonymous substitution numbers to account for base composition bias. By using these methods, we found that mitochondrial genes have 1.7–3.4 times higher synonymous substitution rates than the fastest nuclear genes or 4.5–9.0 times higher rates than the average nuclear genes. The average rate of synonymous transversions was 2.7 (estimated from the melanogaster species subgroup) or 2.9 (estimated from the obscura group) times higher in mitochondrial genes than in nuclear genes. Synonymous transversions in mitochondrial genes occurred at an approximately equivalent rate to those in the fastest nuclear genes. This last result is not consistent with the hypothesis that the difference in turnover rates between mitochondrial and nuclear genomes is the major factor determining higher synonymous substitution rates in mtDNA. We conclude that the difference in synonymous substitution rates is due to a combination of two factors: a higher transitional mutation rate in mtDNA and constraints on nuclear genes due to selection for codon usage. Received: 27 November 1996 / Accepted: 8 May 1997     

Immunoblotting of mite aeroallergens collected with an indoor Burkard air sampler

We examined the kinetics of airborne levels of mite allergen particles in a house by combined use of an indoor Burkard air sampler and immunoblotting. Airborne mite allergens collected on the Burkard sampling tape were transferred onto a nitrocellulose membrane, reacted with mouse monoclonal anti-mite allergen (Der pI) antibody, then treated with alkaline phosphatase conjugated anti-mouse IgG. Finally, the blotted allergen on the membrane was reacted with BCIP/NBT phosphatase, and purple spots visible by the naked eye were produced. The shape of the spots was observed under a microscope, and the spot area was measured by an image processor. This technique might be useful for analyzing the behavior of airborne allergen particles in indoor environments.     

Rapid Identification by Polymerase Chain Reaction of Staphylococcal Exfoliative Toxin Serotype A and B Genes

A new system was designed to detect staphylococcal exfoliative toxin A (ETA) and B (ETB) genes by the polymerase chain reaction (PCR). The primer pairs for the ETA gene (eta) were 20 and 20-mer, and its PCR product was a 741-bp eta fragment, while the primer pairs for the ETB gene (etb) were also 20 and 20-mer, and its PCR product was a 629-bp etb fragment. When these primers were simultaneously used in the PCR, the two types of ET were clearly detected as two bands in an ETA and ETB double-producer using only one colony within 3 hr. We examined 66 strains of Staphylococcus aureus isolated from patients with staphylococcal scalded skin syndrome (SSSS) and compared the results obtained by ELISA and PCR. The same results were obtained for 56 of the strains, i.e., 30 strains were ETA producers, 20 strains were ETB producers, and 6 strains were double-producers. However, positive results were obtained for 5 of the 10 non-ET-producing strains. Two of these strains were judged by PCR as ETA producers and three as ETB producers. Thus, PCR is very sensitive and rapid in detecting ETA and ETB gene fragments in colonies isolated from patients with SSSS.     

In vitro microsome-mediated aflatoxin B1-DNA binding and its inhibition by cytosol of various organs of the hamster and quail

We studied thein vitro activation of aflatoxin B1 (B1) by microsomes and its inactivation by the cytosol of various quail and hamster organs, using B1-DNA binding as an index. The microsomal activity of the liver to bind B1 to DNA was not largely different between the two species and was higher than that of the other organs examined in either species. The microsomal activity of the kidney and lung was very low in the quail compared with the hamster, indicating the very small contribution of the lung and kidney microsomes to the activation of B1 in birds. Only the hamster liver cytosol showed strong inhibition of microsome-mediated B1-DNA binding.     

Switching dynamics and the transient memory storage in a model enzyme network involving Ca2+/calmodulin-dependent protein kinase II in synapses

 The signal processing through a chain of phosphorylation-dephosphorylations mediated by a pair of enzymes, Ca²⁺/calmodulin-dependent protein kinase II and the associated phosphatase, is formulated as a non-autonomous dynamical system in the framework of non-autocatalytic, intraholoenzyme reaction dynamics. A classification of switching characteristics of the system is made in the parameter space comprising the three controllable system parameters: an input-pulse intensity and initial concentrations of the two associated enzymes. It is found that a region of parameter space exists termed the transition zone, that exhibits a quasi-switching behaviour characterized by a signal storage time being prolonged by more than several orders of magnitude (10⁴ times in certain cases) for the increase of two orders of magnitude in the input signal intensity. The effect of alterations of certain rate constants on the quasi-switching property is explored. It is numerically demonstrated that the Ca²⁺/calmodulin-dependent kinase II-related phosphatase is the most important key enzyme for regulating the signal storage time. Received: 25 April 1994/Accepted in revised form: 16 December 1994     

Alcohol and aldehyde dehydrogenase genotypes and drinking behavior of Chinese living in Shanghai

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), the principal enzymes responsible for oxidative metabolism of ethanol, exist in multiple, genetically determined molecular forms. Widely different kinetic properties in some of these isozymes account for the individual differences in alcohol sensitivity. In this study we used the polymerase chain reaction/restriction fragment length polymorphism method to determine the genotypes of the ADH2 and ALDH2 loci of alcoholic and nonalcoholic Chinese living in Shanghai. We also investigated the subjects' drinking patterns by means of semistructured interviews. The alcoholics had significantly lower frequencies of the ADH2² and ALDH2² alleles than did the nonalcoholics, suggesting the inhibitory effects of these alleles for the development of alcoholism. In the nonalcoholic subjects, ADH2² had little, if any, effect, despite the significant effect of the ALDH2² allele in decreasing the alcohol consumption of the individual. Taken together, these results fit the proposed hypothesis for the development of alcoholism, i.e., drinking behavior is greatly influenced by the individual's gentoypes of alcohol-metabolizing enzymes, and the risk of becoming alcoholic is proportionate with the ethanol consumption of the individual.     

Characterization of Methanosarcina mazeii TMA isolated from a paddy field soil

We isolated a methanogenic strain, designated as strain TMA (=DSM 9195), from an enrichment culture inoculated with a Japanese paddy field soil. Strain TMA was Gram positive and strictly anaerobic. Cell shape was pseudosarcina-like, and cells were nonmotile. The strain was able to use methylamines, methanol, H₂–CO₂, and acetate as substrates for methanogenesis, but did not utilize formate. The optimum temperature and optimum pH were 30–37°C and 6.5–7.5 respectively. The G+C content of the DNA was 42.1 mol %. Strain TMA had DNA-DNA hybridization values of more than 80% with Methanosarcina mazeii S-6^T (T = type strain). On the basis of phenotypic and genotypic characteristics, we identified strain TMA as M. mazeii. This is the first methylotrophic methanogen isolated from a paddy field soil and identified to the species level.