Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath.

Complex environments, such as molecular matrices and biological material, play a fundamental role in many important dynamic processes in condensed phases. Because it is extremely difficult to conduct full quantum dynamics simulations on such environments due to their many degrees of freedom, here, we treat in detail the environment only around the main system of interest (the subenvironment), while the other degrees of freedom needed to maintain the equilibrium temperature are described by a simple harmonic bath, which we call a quantum thermostat. The noise generated by the subenvironment is spatially non-local and non-Gaussian and cannot be characterized by the fluctuation-dissipation theorem.

Optical response of laser-driven charge-transfer complex described by Holstein-Hubbard model coupled to heat baths: Hierarchical equations of motion approach.

We investigate the optical response of a charge-transfer complex in a condensed phase driven by an external laser field. Our model includes an instantaneous short-range Coulomb interaction and a local optical vibrational mode described by the Holstein-Hubbard (HH) model. Although characterization of the HH model for a bulk system has typically been conducted using a complex phase diagram, this approach is not sufficient for investigations of dynamical behavior at finite temperature, in particular for studies of nonlinear optical properties, where the time irreversibility of the dynamics that arises from the environment becomes significant.

Identification and characterisation of structural maintenance of chromosome 1 (smc1) mutants of Coprinopsis cinerea.

A Coprinopsis cinerea homokaryotic fruiting strain was mutagenised, identifying a mutant that exhibited a hyphal growth temperature sensitive defect and hyphal knot development defect at an early fruiting stage, even at the hyphal growth permissive temperature. Microscopic observation suggested that the mutant nuclei exhibited defects in the metaphase to anaphase transition at the restrictive temperature. The gene in which the mutation occurred was cloned, sequenced and determined to be homologous to smc1.

Role of overlapping glycosylation sequons in antigenic properties, intracellular transport and biological activities of influenza A/H2N2 virus haemagglutinin.

The haemagglutinin (HA) protein of influenza A/H2N2 virus possesses five oligosaccharide attachment sites, two of which have overlapping glycosylation sequons at positions 20-23 (NNST) and 169-172 (NNTS). Here, the role of these two oligosaccharide attachment sites is investigated with regard to antigenic property, intracellular transport and biological activity of the HA protein. Glycosylation-site HA mutants with mutation(s) in their overlapping glycosylated sequons, each of which had one or two oligosaccharide attachment sites removed, were constructed.

Effect of addition of new oligosaccharide chains to the globular head of influenza A/H2N2 virus haemagglutinin on the intracellular transport and biological activities of the molecule.

The haemagglutinin (HA) of influenza A/H2N2 virus possesses six antigenic sites (I-A to I-D, II-A and II-B), and sites I-A, I-B and I-C are located in the regions corresponding to sites A, B and D on the H3 HA. We demonstrated previously that most escape mutants selected by mAbs to site I-A, I-B or I-C had acquired a new oligosaccharide at position 160, 187 or 131, respectively, but this has never occurred during circulation of A/H2N2 virus in humans. Here, to examine whether the H2 HA has the potential to gain two new oligosaccharides on its tip, 31 double escape mutants were isolated by using a single escape mutant with an oligosaccharide at position 160, 187 or 131 as a parental virus and a mAb to an antigenic site different from that to which the mAb used for selection of the parental virus was directed as a selecting antibody, but there were no mutants with two new oligosaccharides.

Antigenic structure of the haemagglutinin of human influenza A/H2N2 virus.

The antigenic structure of influenza A/H2N2 virus haemagglutinin (HA) was analysed using 19 monoclonal antibodies (MAbs) against the HA of A/Kayano/57. The antibodies were classified into three groups: group I had both haemagglutination inhibition and neutralization activities, group II had neutralization activity but no haemagglutination inhibition activity and group III had neither activity. Analysis of escape mutants selected by each of the group I and II antibodies identified six distinct antigenic sites: four (I-A to I-D) were recognized by group I MAbs and two (II-A and II-B) were recognized by group II MAbs.

The sites for fatty acylation, phosphorylation and intermolecular disulphide bond formation of influenza C virus CM2 protein.

The sites for fatty acylation, disulphide bond formation and phosphorylation of influenza C virus CM2 were investigated by site-specific mutagenesis. Cysteine 65 in the cytoplasmic tail was identified as the site for palmitoylation. Removal of one or more of three cysteine residues in the ectodomain showed that all of cysteines 1, 6 and 20 can participate in the formation of disulphide-linked dimers and/or tetramers, although cysteine 20 may play the most important role in tetramer formation.

Phylogenetic analysis of influenza C virus nonstructural (NS) protein genes and identification of the NS2 protein.

The nucleotide sequences of RNA segment 7 (nonstructural protein gene; NS) were compared among 34 influenza C virus strains isolated between 1947 and 1992. The results showed that all the NS genes analysed had the potential to encode NS1 and NS2 proteins of 246 and 182 amino acids, respectively. The deduced amino acid sequence of the previously unidentified NS2 was fairly well conserved, although it was more divergent than the NS1 protein sequence.