Correlations in one-dimensional fully developed chaos

Correlations in the baker map and the tent map as examples of one-dimensional, fully developed chaos are considered. It is shown, utilizing symbolic dynamical systems derived from these maps, that the vanishing second-order correlation function is not sufficient to guarantee uncorrelatedness. Importance of the higher-order, especially third-order, correlation functions is emphasized for chaotic systems. In search of the quantities that grasp correlational behaviors as a whole in chaotic systems, it is proposed to use the fixed-separation correlation integral, which is a modified quantity of the usual correlation integral devised to calculate the fractal dimension of strange attractors, for these maps. It is shown that the new quantity contains all the even-number orders of autocorrelation function that are commonly considered.     

Characterization of a chloroplast DNA sequence from Chlorella ellipsoidea that promotes autonomous replication in yeast

Summary An EcoRI 2.7 kbp fragment from Chlorella ellipsoidea chloroplast DNA (cpDNA) cloned in YIp5 was shown to promote autonomous replication in Saccharomyces cerevisiae. The fragment was localized in the small single copy region close to the inverted repeat. The ARS activity (autonomously replicating sequences in yeast) was found to be confined within a subclone of a ca. 300 bp HindIII fragment. Sequence analysis of this fragment revealed its high AT content and the presence of several direct and inverted repeats and a few elements that were related to the yeast ARS consensus sequence. Electron microscopic studies revealed that this sequence did not coincide with the primary replication origin of chloroplast DNA. The functioning of this sequence as a possible origin of plasmid replication in vivo is discussed. This is the first report on Chlorella cpDNA sequence. re]19850821 rv]19851211 ac]19851216     

Selective accumulation of heavy metals by microorganisms

Summary An investigation of the removal and recovery of urnnium from aqueous systems using microbial biomass has been described previously (Nakajima et al. 1982). To establish which microorganisms accumulate the most uranium, we extended our investigation of uranium uptake to 83 species of microorganisms, 32 bacteria, 15 yeasts, 16 fungi and 20 actinomycetes. Of these 83 species of microorganisms tested, extremely high uranium-absorbing ability was found in Pseudomonas stutzeri, Neurospora sitophila, Streptomyces albus and Streptomyces viridochromogenes.The selective accumulation of heavy metal ions by various microorganisms has also been examined. Uranyl, mercury and lead ions were readily accumulated by almost all the species of microorganisms tested. Actinomycetes and fungi differ from many bacteria and most yeasts in their selective accumulation of uranium and mercury.In addition to this fundamental research, uranium recovery was investigated in immobilized Streptomyces albus, a microorganism with high uranium-uptake ability. These immobilized cells adsorbed uranium readily and selectively. The immobilized cells recovered uranium almost quantitatively and almost all uranium absorbed was desorbed with 0.1 M Na₂CO₃. The dry weight of the free cells decreased by 50% during 5 adsorption-desorption cycles. However, the dry weight of the immobilized cells decreased by only 2% during 5 cycles. These results showed that microbial cells are more stable after immobilization and can be used repeatedly for the process of uranium adsorption-desorption.     

The hemolymph coagulation system in invertebrate animals

A hemocyte lysate from horseshoe crab produced a gel, when exposed to Gram-negative bacterial endotoxins. This gelation reaction of the lysate, so-called Limulus test, has been widely employed as a simple and very sensitive assay method for endotoxins. Recent biochemical studies on the principle of Limulus test indicate that the hemocytes contain several serine protease zymogens, which constitute a coagulation cascade triggered by endotoxins, and that there is a (1 3)--d-glucan-mediated coagulation pathway which also results in the formation of gel. Up to now, six protein components, designated coagulogen, proclotting enzyme, factor B, factor C, factor G and anti-LPS factor, all of which are closely associated with the endotoxin-mediated coagulation pathway, have been purified and biochemically characterized. Among these components, the complete amino acid sequences of coagulogens isolated from one American and three Asian species of horseshoe crabs have been established. Moreover, the reconstitution experiment using the isolated clotting factors, C, B, proclotting enzyme and coagulogen in the presence of endotoxin, leads to the formation of coagulin get. Based on these results, we propose here a mechanism for the Limulus coagulation cascade.     

A soybean growth model based on compensatory growth following defoliation

On the basis of an artificial defoliation experiment, a new growth model of soybean was formulated through a modification of Rudd's (1980) model with regard to his equations for dry matter allocation. Compensatory growth for leaf damage was modelled by a single process in which the dry matter allocation changes dynamically according to the severity of leaf damage. The sums of squared differences between simulations and experimental soybean yields were much smaller in our modified model than in Rudd's original model. The modified model gave a better simulation of yield loss due to defoliation that varied in time and intensity. The relationship between various times and intensities of defoliation and yield loss was shown, which is essential for establishing the dynamic economic injury level in IPM.     

Inhibitory effect of long chain fatty acyl CoAs on RNA polymerase from Escherichia coli

RNA polymerase from Escherichia coli was inhibited by long chain fatty acyl CoAs, such as myristoyl CoA (Ki = 17.2 microM), palmitoyl CoA (Ki = 8.9 microM), oleoyl CoA (Ki = 5.5 microM), and stearoyl CoA (Ki = 0.94 microM). The inhibition by these CoA thioesters was non-competitive against nucleoside triphosphates. Short chain fatty acyl CoAs, such as acetyl CoA, propionyl CoA, acetoacetyl CoA, butyryl CoA, and decanoyl CoA, failed to inhibit RNA polymerase. CoA, Na-myristate, Na-palmitate, Na-oleate, Na-stearate, palmitoyl carnitine, and carnitine did not inhibit the enzyme. The inhibition of RNA polymerase by long chain fatty acyl CoAs was competitive against template DNA.     

Transformation of L cells with virus thymidine kinase genes introduced by red cell-mediated microinjection

Fusion of red cell ghosts containing foreign materials with cells results in the introduction of the materials into the cells (red cell-mediated microinjection). Until now, 'two-step dialysis' has mainly been used for trapping proteins in the ghosts. Large-sized materials such as DNA, however, are rarely trapped in the ghosts, since the holes in the red cell membrane caused by osmotic shock are too small for such materials to pass through. In this study, we improved the trapping technique. Some of the Hind III fragments of lambda phage DNA as well as proteins could be trapped in the ghosts when the mixture of these materials and red cells were frozen at -80 degrees C for a short period followed by quick thawing. Red cell-mediated microinjection using ghosts containing plasmid pBR322 linked with a Herpes simplex viral thymidine kinase (tk) gene brought about transformation of tk-defective L cells, the efficiency of transformation was 1 out of 20 000-60 000 cells fused with the ghosts.     

Codon Substitution in Evolution and the "Saturation" of Synonymous Changes

A mathematical model for codon substitution is presented, taking into account unequal mutation rates among different nucleotides and purifying selection. This model is constructed by using a 61 X 61 transition probability matrix for the 61 nonterminating codons. Under this model, a computer simulation is conducted to study the numbers of silent (synonymous) and amino acid-altering (nonsynonymous) nucleotide substitutions when the underlying mutation rates among the four kinds of nucleotides are not equal. It is assumed that the substitution rates are constant over evolutionary time, the codon frequencies being in equilibrium, and, thus, the numbers of synonymous and nonsynonymous substitutions both increase linearly with evolutionary time. It is shown that, when the mutation rates are not equal, the estimate of synonymous substitutions obtained by F. Perler, A. Efstratiadis, P. Lomedico, W. Gilbert, R. Kolodner and J. Dodgson's "Percent Corrected Divergence" method increases nonlinearly, although the true number of synonymous substitutions increases linearly. It is, therefore, possible that the "saturation" of synonymous substitutions observed by Perler et al. is due to the inefficiency of their method to detect all synonymous substitutions.     

Vasorelaxing actions of molsidomine and its metabolites, in comparison with nitroglycerin

The effect of a novel antianginal agent, molsidomine (N-ethoxycarbonyl-3-morpholinosydnonimine) (SIN-10) and its metabolites, 3-morpholinosydnonimine (SIN-1) and N-nitroso-N-morpholinoaminoacetonitrile (SIN-1A) on isolated dog blood vessels were investigated. SIN-1 and SIN-1A elicited a concentration-dependent relaxation of prostaglandin F2 alpha, contracted strips, while SIN-10 was without effect even in a concentration of 10(-4) M. The mean effective concentration (EC50) values of SIN-1A were much lower than SIN-1 and other vasodilators including nitroglycerin. The time course of relaxation was more rapid and transient in response to SIN-1A than to SIN-1. Adrenergic and cholinergic blocking agents did not affect the relaxing responses to SIN-1 and SIN-1A. SIN-1A also attenuated the norepinephrine-, KCl-, Ca2+-, or electrical transmural stimulation-induced contractile response, but SIN-1A increased the [3H]norepinephrine release from the adrenergic nerve terminals in response to transmural stimulation. Methemoglobin, which reportedly binds nitric oxide, or methylene blue, an inhibitor of guanylate cyclase, attenuated the relaxing response to SIN-1A. These results indicate that the vasodilating action of molsidomine results from the direct action on the vascular smooth muscle and suggest that the action is caused by its metabolites, probably SIN-1A, which contains a nitric oxide-moiety in the molecule. The possible mechanism of vasorelaxing action of SIN-1A is discussed in comparison with that of nitroglycerin.