Comparative mineral and hormonal analyses of wild type and TLS somaclonal variant derived from oil palm (Elaeis guineensis Jacq. var. tenera) tissue culture

Comparative mineral and hormonal analyses were made on tissue culture derived truncated leaf syndrome and wild type oil palm seedlings. Mineral analysis confirmed that Boron, Zinc and chlorophyll levels were significantly lower in truncated leaf syndrome leaves than those of wild type. Hormonal analysis also revealed various cytokinin derivatives such as trans-zeatin, trans-zeatin riboside, trans-zeatin O-glucoside and trans-zeatin riboside 5??mono phosphate were significantly higher in truncated leaf syndrome leaves compared to wild type leaves. Brassinolide level was also significantly higher in truncated leaf syndrome leaves than those of the wild type. These observations suggest that the truncated leaf syndrome abnormality could be associated to high cytokinin and brassinosteroid production which affects the uptake of Boron and Zinc.     

Quantification of Clostridium botulinum type A toxin and organisms in the feces of a case of infant botulism and examination of other related specimens

Bacteriological examinations were performed on the first case of infant botulism in Japan (an infant boy aged 79 days at onset of illness). Clostridium botulinum type A toxin and organisms were detected continually in the stools of the infant for at least 31 days and 39 days, respectively. The highest levels of the toxin and of the population of the organisms, 7.8 X 10(4) LD50/g and 1.3 X 10(6) colony forming units (cfu)/g, were detected in the stool specimen taken on the 20th day of illness. Type A organisms were detected also in the honey fed to the infant before onset of illness, teats of his feeding bottle, soil specimens taken at the house entry and the vacuum-cleaner dust. Fecal excretion of the toxin and organisms was no longer detected from the 68th day of illness and he recovered.     

Effects of hydrated water on protein unfolding

The conformational stability of a protein in aqueous solution is described in terms of the thermodynamic properties such as unfolding Gibbs free energy, which is the difference in the free energy (Gibbs function) between the native and random conformations in solution. The properties are composed of two contributions, one from enthalpy due to intramolecular interactions among constituent atoms and chain entropy of the backbone and side chains, and the other from the hydrated water around a protein molecule. The hydration free energy and enthalpy at a given temperature for a protein of known three-dimensional structure can be calculated from the accessible surface areas of constituent atoms according to a method developed recently. Since the hydration free energy and enthalpy for random conformations are computed from those for an extended conformation, the thermodynamic properties of unfolding are evaluated quantitatively. The evaluated hydration properties for proteins of known transition temperature (Tm) and unfolding enthalpy (delta Hm) show an approximately linear dependence on the number of constituent heavy atoms. Since the unfolding free energy is zero at Tm, the enthalpy originating from interatomic interactions of a polypeptide chain and the chain entropy are evaluated from an experimental value of delta Hm and computed properties due to the hydrated water around the molecule at Tm. The chain enthalpy and entropy thus estimated are largely compensated by the hydration enthalpy and entropy, respectively, making the unfolding free energy and enthalpy relatively small. The computed temperature dependences of the unfolding free energy and enthalpy for RNase A, T4 lysozyme, and myoglobin showed a good agreement with the experimental ones.(ABSTRACT TRUNCATED AT 250 WORDS)     

Amino acid sequence homology applied to the prediction of protein secondary structures, and joint prediction with existing methods

The assumption that homologous segments in different proteins may share a similar conformation is applied to the prediction of secondary structures in proteins. Sequences homologous to a target protein are searched, without allowing any gap, and compared against a number of reference proteins of known three-dimensional structure, and then a conformational state (alpha, beta or coil) for each residue of the protein is predicted by looking at the secondary structure of corresponding homologous segments. This prediction is done in a statistical rather than 'deterministic' way, by assigning the most probable conformation state among homologous data to each residue site of a target protein. A test application for 22 sample proteins yields 60% correctness on the average, a better value in comparison with two other existing methods. Joint prediction combining three methods into one is shown to increase the reliability up to 70%, when only the regions identically predicted with the three methods are taken into account. Application of the present method to 10 proteins of unknown structure is demonstrated.     

Amino acid substitutions in mitochondrial ATPase subunit 9 of Saccharomyces cerevisiae leading to oligomycin or venturicidin resistance

A series of isonuclear oligomycin-resistant mutants of Saccharomyces cerevisiae carrying mutations in the mitochondrial oli1 gene has been studied. DNA sequence analysis of this gene has been used to define the amino acid substitutions in subunit 9 of the mitochondrial ATPase complex. A domain of amino acids involved in oligomycin resistance can be recognized which encompasses residues in each of the two hydrophobic portions of the subunit 9 polypeptide that are thought to span the inner mitochondrial membrane. Certain amino acid substitutions also confer cross-resistance to venturicidin: these residues define an inner domain for venturicidin resistance. The expression of venturicidin resistance resulting from one particular substitution is modulated by nuclear genetic factors.     

Examination of protein sequence homologies: III. Ribosomal protein YS25 fromSaccharomyces cerevisiae and its counterparts fromSchizosaccharomyces pombe,rat liver,andEscherichia coli

Summary The sequences of the ribosomal proteins YS25, SP-S28, RL-S21, and Ec-S6, fromSaccharomyces cerevisiae, Schizosaccharomyces pombe, rat liver, andEscherichia coli, respectively, have been examined using a computer program that searches for homologous tertiary structures. Matrices of comparisons among the eukaryotic sequences show that they match each other sequentially without any internal gaps. The average values of the correlation coefficients obtained from the comparison matrices are higher for the first halves of the sequences than for the latter halves. This result suggests that the first halves of the sequences may represent a more important domain than the latter halves. The comparison matrices between the eukaryotic and bacterial sequences of ribosomal proteins, however, do not show sequentially arranged homology, though there are six well-matching segments arranged in different orders in the two types of sequences. This implies that the eukaryotic sequences of the ribosomal protein were reconstituted by two internal transpositions and six deletions of 4–12 residues each from the ancestral sequence during the divergence between bacterial and eukaryotic genes. These findings may give insight into structural and quantitative studies of evolutionary divergence between eukaryotes and prokaryotes.