Charge-transfer excitations steer the Davydov splitting and mediate singlet exciton fission in pentacene.

Quantum-chemical calculations are combined to a model Frenkel-Holstein Hamiltonian to assess the nature of the lowest electronic excitations in the pentacene crystal. We show that an admixture of charge-transfer excitations into the lowest singlet excited states form the origin of the Davydov splitting and mediate instantaneous singlet exciton fission by direct optical excitation of coherently coupled single and double exciton states, in agreement with recent experiments.

Interplay between intrachain and interchain interactions in semiconducting polymer assemblies: the HJ-aggregate model.

A new model for analyzing the photophysics of polymer aggregates is introduced taking into account exciton motion along a polymer chain and across polymer chains. Excitonic coupling and vibronic coupling are treated on equal footing using a Holstein-based Hamiltonian represented in a multi-particle basis set. In the HJ-aggregate model the competition between intrachain (through-bond) coupling leading to Wannier-Mott excitons, and interchain (through-space) coupling leading to Frenkel excitons, is studied in detail for two model dimers: one composed of red-phase polydiacetylene (PDA) chains and the other composed of regioregular P3HT chains. The resulting photophysical properties are shown to depend critically on the relative magnitudes of the intrachain and interchain exciton bandwidths. Dominant intraband (interband) coupling favors a photophysical response resembling J-aggregates (H-aggregates). In PDA dimers, where intrachain coupling prevails, the absorption spectrum is dominated by the 0-0 peak, as is characteristic of J-aggregates. The photoluminescence (PL) spectrum displays hybrid character: the ratio of the main (0-0) band to the first vibronic sideband intensities is initially zero at T = 0 K due to the forbidden nature of the 0-0 transition, but then increases with temperature in a manner characteristic of H-aggregates, peaking when kT ≈ ΔE, where ΔE is the interchain splitting. Further increases in temperature result in a decline of the PL ratio, as in a J-aggregate. This remarkable H to J transition is also predicted for the temperature dependence of the radiative decay rate, k(rad). The maximum (peak) rate scales as, k(rad) (max)∼(W(intra)/W(inter))(1/2), where W(intra) (W(inter)) is the intrachain (interchain) exciton bandwidth. Hence, when W(intra) is sufficiently larger than W(inter) the dimer displays thermally activated superradiance. In P3HT the intrachain coupling is far weaker than in PDA making the intrachain and interchain couplings comparable in the crystalline phase. Although the absorption spectral line shape is still well-accounted for by the conventional H-aggregate model, the photoluminescence is more sensitive, with H or J behavior tunable by changes in morphology. Long range intrachain order which coincides with weaker interchain interactions induces J-aggregate behavior, while short range intrachain order and the resulting stronger interchain coupling induces H-aggregate behavior. Our predictions neatly account for the H-like dominance exhibited by the PL from spin-cast films and the J-like dominance exhibited by the PL from highly ordered P3HT nanofibers self-assembled in toluene.

Male death resulting from hybridization between subspecies of the gypsy moth, Lymantria dispar.

We explored the origin of all-female broods resulting from male death in a Hokkaido population of Lymantria dispar through genetic crosses based on the earlier experiments done by Goldschmidt and by testing for the presence of endosymbionts that are known to cause male killing in some insect species. The mitochondrial DNA haplotypes of the all-female broods in Hokkaido were different from those of normal Hokkaido females and were the same as those widely distributed in Asia, including Tokyo (TK). Goldschmidt obtained all-female broods through backcrossing, that is, F1 females obtained by a cross between TK females (L. dispar japonica) and Hokkaido males (L. dispar praeterea) mated with Hokkaido males. He also obtained all-male broods by mating Hokkaido females with TK males. Goldschmidt inferred that female- and male-determining factors were weakest in the Hokkaido subspecies and stronger in the Honshu (TK) subspecies. According to his theory, the females of all-female broods mated with Honshu males should produce normal sex-ratio broods, whereas weaker Hokkaido sexes would be expected to disappear in F1 or F2 generations after crossing with the Honshu subspecies. We confirmed both of Goldschmidt's results: in the case of all-female broods mated with Honshu males, normal sex-ratio broods were produced, but we obtained only all-female broods in the Goldschmidt backcross and obtained an all-male brood in the F1 generation of a Hokkaido female crossed with a TK male. We found no endosymbionts in all-female broods by 4,'6-diamidino-2-phenylindole (DAPI) staining. Therefore, the all-female broods observed in L. dispar are caused by some incompatibilities between Honshu and Hokkaido subspecies.

Vibronic coupling in quantum wires: applications to polydiacetylene.

A theory describing vibronic coupling in direct band gap, one-dimensional semiconductors is developed to account for the photophysical properties of isolated, defect-free conjugated polymers. A Holstein-like Hamiltonian represented in a multi-particle basis set is used to evaluate absorption and emission due to Wannier-Mott excitons. The photophysical properties of such quantum wires are shown to strongly resemble those of Frenkel exciton J-aggregates. The 1(1)B(u) exciton coherence length and effective mass are readily determined from the ratio of the 0-0 and 0-1 line strengths, I(0 - 0)/I(0 - 1), in the photoluminescence spectrum. I(0 - 0)/I(0 - 1) is shown to follow a T(-1/2) dependence, in an excellent agreement with experiments on the red-phase of polydiacteylene.

The nature of singlet excitons in oligoacene molecular crystals.

A theory for polarized absorption in crystalline oligoacenes is presented, which includes Frenkel exciton coupling, the coupling between Frenkel and charge-transfer (CT) excitons, and the coupling of all neutral and ionic excited states to the dominant ring-breathing vibrational mode. For tetracene, spectra calculated using all Frenkel couplings among the five lowest energy molecular singlet states predict a Davydov splitting (DS) of the lowest energy (0-0) vibronic band of only -32 cm(-1), far smaller than the measured value of 631 cm(-1) and of the wrong sign-a negative sign indicating that the polarizations of the lower and upper Davydov components are reversed from experiment. Inclusion of Frenkel-CT coupling dramatically improves the agreement with experiment, yielding a 0-0 DS of 601 cm(-1) and a nearly quantitative reproduction of the relative spectral intensities of the 0-n vibronic components. Our analysis also shows that CT mixing increases with the size of the oligoacenes. We discuss the implications of these results on exciton dissociation and transport.

The Ro/SSA autoantigen as an immunogen. Some anti-Ro/SSA antibody binds IgG.

The rheumatic disease autoantigen, Ro/SSA, was immunogenic to a rabbit host. The heteroimmune rabbit serum bound the Ro/SSA particle in immunoblots and in an ELISA. Both the rabbit anti-Ro/SSA and a human prototype anti-Ro/SSA serum also bound IgG; and moreover, IgG inhibited both rabbit and human anti-Ro/SSA activity. Anti-IgG activity of the rabbit and human anti-Ro/SSA sera bound Ro/SSA by Western blot and solid-phase assays. In addition, purified Ro/SSA inhibited the anti-IgG activity of the anti-Ro/SSA sera from rabbit and man. Affinity purification of the IgG- and Ro/SSA-binding fractions of the rabbit anti-Ro/SSA demonstrated that both the anti-Ro/SSA and anti-IgG activities were concentrated in these fractions. These data show that Ro/SSA and IgG share epitopes that are bound by anti-Ro/SSA antibody. Inhibition experiments suggest that this antibody is found in most human anti-Ro/SSA autoimmune sera and that the epitope(s) are found in the F(ab')2 fragment of IgG.

Identification of homozygous deletions of tumor suppressor gene FAT in oral cancer using CGH-array.

Homozygous deletions (HD) provide an important resource for identifying the location of candidate tumor suppressor genes. To identify the tumor suppressor gene in oral cancer, we employed high-resolution comparative genomic hybridization (CGH)-array analysis. We identified a homozygous loss of FAT (4q35), a new member of the human cadherin superfamily, from genome-wide screening of copy number alterations in one primary oral cancer. This result was evaluated by genomic polymerase chain reaction in 13 oral cancer cell lines and 20 primary oral cancers and Southern blot in the cell lines. We found frequent exonic HD of FAT in the cell lines (3/13, 23%) and in primary oral cancers (16/20, 80%). FAT expression was absent in these cell lines. Homozygous deletion hot spots were observed in exon 1 (9/20, 45%) and exon 4 (7/20, 35%). Moreover, loss of gene expression was identified in other types of squamous cell carcinoma. The methylation status of the FAT CpG island in squamous cell carcinomas correlated negatively with its expression. Our results identify mutations in FAT as an important factor in the development of oral cancer and indicate the importance of FATs function in some squamous cell carcinomas.

Heat island mitigation using water retentive pavement sprinkled with reclaimed wastewater.

In Japan, reclaimed wastewater has been recycled widely for non-potable urban applications and it is to be used for sprinkling roads to mitigate heat island in urban areas. To assess the heat island mitigation effects of the sprinkling reclaimed wastewater on water retentive pavement, we carried out a survey at Shiodome-District, Tokyo. The temperatures of air and roads, humidity, and WBGT (Wet-bulb globe temperature) were measured and heat flux was estimated to compare the condition of the areas with/without sprinkling. The following results were obtained. 1) Sprinkling reclaimed wastewater decreased the road surface temperature by 8 degrees during the daytime and by 3 degrees at night: temperatures equal to those on planting zones. Nevertheless sprinkling was done only in the daytime, the temperature decrease effect was not only obtained during the daytime: it continued through the night, due to the water retentive pavement. 2) Sprinkling reclaimed wastewater reduced the amount of sensible heat flux and increased that of latent heat flux. These results suggest that sprinkling reclaimed wastewater on water retentive pavement can effectively mitigate the heat island phenomenon.

Management of chemical substances in a water environment communicating among stakeholders.

With the implementation of Pollutant Discharge and Transfer Register (PRTR) in fiscal 2003, information on the quantity of chemical substances discharged annually from each business is released in Japan. Such information is expected to lead to heightened public concern about the presence of chemical substances in environment. This paper showed the effects of using PRTR data for managing chemical risk in a water environment communicating among stakeholders based on the results of the case study held in Japan. First, it was possible to identify the discharge sources using PRTR and related data for the chemicals such as Zn and NPs which were shown that they had relatively high risks based on the survey in a model area. Second, it was suggested that the chemical risk communication among the stakeholders including people using PRTR and related data would be a good way to encourage environmental activities of businesses, and to build a good relationship among stakeholders including people who have anxiety about chemical risk.

Molecular properties of the Ro/SSA antigen and enzyme-linked immunosorbent assay for quantitation of antibody.

Antibodies to the Ro/SSA antigen occur in patients with systemic lupus erythematosus and Sjögren's syndrome. An immunoaffinity method for the preparation of electrophoretically homogeneous Ro/SSA antigen is described. Several molecular properties of the antigen have been determined. The native RNA protein particle has a molecular weight of approximately 100,000 D determined by gel filtration. Sodium dodecyl sulfate-analysis of the purified Ro/SSA antigen and analysis by staining of bands with silver and Coomassie Blue, Western blotting, and RNAase treatment leads to a hypothesis for the structure of the particle in which an antigenic 60,000 protein is bound to 24,000-27,000 RNA molecules which are not antigenic. An enzyme-linked immunoabsorbent assay method for assay of anti-Ro/SSA is also described which sensitively measures antigen binding at dilutions of sera containing anti-Ro/SSA precipitins up to 10(7) fold. Normal sera on average have 10(3) less binding activity.

Characterization of a high molecular weight acidic nuclear protein recognized by autoantibodies in sera from patients with polymyositis-scleroderma overlap.

Autoantibodies in the serum from a patient with connective tissue disease have been used to define a high molecule weight acidic nuclear protein antigen. The antigen tentatively termed Ku, after the first two letters of patient's name, has distinct physicochemical properties and immunological specificities that distinguish it from previously reported antigens. The Ku antigen has an apparent 300,000 mol wt as determined by gel filtration and sucrose density gradient ultracentrifugation techniques. The antigen is destroyed by trypsin, mild heating, and pH variations greater than 10 and less than 5. Treatment with ribonuclease or deoxyribonuclease did not affect the antigenic reactivity. The Ku antigen was demonstrated in the soluble extracts of human, calf, and rabbit, but not of rat tissues. Purified antibody localized the Ku antigen within the nuclei of human liver where a "reticular" pattern of immunofluorescence was seen. Of 330 patients with various connective tissue diseases, 9 had precipitating antibodies to the Ku antigen. Preliminary results of clinical analysis indicated that antibody to the Ku antigen might become a useful marker for a group of patients with clinical characteristics of both polymyositis and scleroderma with a good prognosis.

Immunologic and structural studies of the lupus/Sjögren's syndrome autoantigen, La/SSB, with a monoclonal antibody.

La/SSB is a small nuclear RNA protein against which precipitating autoantibodies are made in many patients with systemic lupus erythematosus or Sjögren's syndrome. The recent purification of La/SSB has made structural and immunologic studies possible. Consequently, a mouse hybridoma antibody (La1) was raised, after immunization and fusion, that reacted with bovine La/SSB. Results of inhibition tests with tissue extracts and fluorescent antinuclear antibody tests demonstrated that La1 reacted with bovine extracts and cells, but not with those from human, mouse, or rabbit sources. La1 reacted in Western blot and in an adapted anti-La/SSB enzyme-linked immunosorbent assay with only the 41-kD bovine La/SSB peptide and not with the smaller 29-kD bovine La/SSB peptide. RNA gels showed that La1 bound the La/SSB particle that contained the predominant La/SSB RNA species near 90 nucleotides as well as the minor RNA species, both of which were bound by the human autoimmune anti-La/SSB serum. A solid-phase assay for human autoimmune anti-La/SSB antibody using La1 was more sensitive for the detection of human anti-La/SSB than was a comparable assay using purified La/SSB, and showed that anti-La/SSB is present in nearly all Ro/SSA precipitin-positive sera. Thus, this study demonstrates that monoclonal antibody can be raised against La/SSB; that the protein moiety of bovine La/SSB differs from human, mouse, and rabbit at an epitope on the 41-kD La/SSB peptide; that the RNA bound to the La1-reactive particle was as heterogeneous as that binding the anti-La/SSB autoimmune serum; and that anti-Ro/SSA and anti-La/SSB are closely associated.

Implications of anti-Ro/Sjögren's syndrome A antigen autoantibody in normal sera for autoimmunity.

We have applied a sensitive assay to analyze lupus and Sjögren's syndrome autoantibodies in 40 normal sera. Seven of these bound Ro/Sjögren's syndrome A antigen (SSA). Although this binding was 1,000-fold lower than the highest anti-Ro/SSA level measured from patients, it was inhibited by human Ro/SSA. Positive normal serum-bound Ro/SSA in Western immunoblots and binding activity was demonstrated in the F(ab')2 fragment of IgG. Affinity purification of normal anti-Ro/SSA IgG increased the specific anti-Ro/SSA binding by greater than 17-fold. This purified antibody formed a Ro/SSA precipitin and had a relative affinity for Ro/SSA identical to that of Ro/SSA precipitin-positive patients. These data demonstrate that the anti-Ro/SSA present in healthy normal donors is true autoantibody. Anti-La/Sjögren's syndrome B antigen (SSB) autoantibodies were found in 3 of the 40 normal sera, while none bound nuclear ribonucleoprotein (Sm). Finding low levels of anti-Ro/SSA and anti-La/SSB among normals may indicate that anti-Ro/SSA and anti-La/SSB occur in disease by enhancement of a preexisting immune response.

Risk evaluation for staphylococcal food poisoning in processed milk produced with skim milk powder.

The growth of S. aureus and the production of staphylococcal enterotoxin A (SEA) in skim milk concentrates stored at inappropriate temperatures in a recovery milk tank (tank for excess concentrated skim milk) used in the manufacture of skimmed milk powder were investigated. Also, it was estimated if a possible outbreak of food poisoning would occur if the contaminated skimmed milk powder was used in the manufacture of processed milk. Skim milk concentrates with milk solid content of 15, 25, and 35% were inoculated with S. aureus at 1-2 log CFU/ml and incubated at 15, 25, or 35 degrees C for 0 to 24 h with or without shaking. Bacterial growth and the level of SEA production were measured. At 35 degrees C with shaking, there was a significant difference (p<0.05) in one way layout analysis of variance, and it was demonstrated that the growth of S. aureus and SEA production could be milk solid content-dependent. Shaking accelerated the growth of S. aureus and SEA production at 35 degrees C. Generally, skim milk powder is produced by mixing a set percentage of skim milk concentrates (recovery milk) from the recovery milk tank into raw milk. If recovery milk contaminated with S. aureus at levels of 1-2 log CFU/ml is kept at 15 to 35 degrees C due to a power failure, it was estimated that processed milk consumption of 670-1200 ml, 420-1500 ml and 18-83 ml would trigger the onset of food poisoning symptoms when skim milk concentrates (recovery milk) are stored at 25 degrees C for 24 h, 35 degrees C for 10 h, and 35 degrees C for 24 h, respectively, during the production of the skim milk powder. Based on these consumption levels, it was concluded that, if recovery milk cannot be refrigerated and is stored at room temperature (25 to 35 degrees C), it must be used within 8 h and preferably within 6 h.

Comprehensive management of chemical substances in a water environment using PRTR data.

The annual quantity of discharge of 354 chemical substances from each business has been released based on PRTR law in Japan since 2003. MLIT and municipalities should be responsible for managing chemical risk in public water bodies through communication with stakeholders, such as the public and businesses. However, it is economically difficult to measure the discharge loads and behaviour of all chemical substances and reveal which substances should be particularly managed in each basin. NILIM has begun studies on survey methods to understand the discharge and behaviour of chemical substances in each basin based on PRTR information, and to conduct risk management of chemical substances in cooperation with stakeholders such as the public and businesses. We selected 30 chemical substances, such as those listed or nominated in environmental criteria and endocrine disrupters, collected the volume of discharge of chemical substances from public and industrial wastewater treatment plants using PRTR information, and surveyed their behaviour in the river in the model area. As a result, the discharge of 12 chemical substances were reported in PRTR, and 17 substances were detected in the river. Some inorganic compounds were detected intensively near discharge sites reported in the PRTR. But some organic compounds and endocrine disrupters, such as oestrone, were detected although their discharge was not reported in the model area in the PRTR. It suggested that PRTR information is useful to identify hot spots, but further study is needed to understand the discharge of chemical substances from small businesses, farmland and houses.

Cloning of dnaK and dnaJ homologous genes from a purple non-sulfur bacterium Rhodopseudomonas species.

The dnaK and dnaJ genes were isolated as a cluster from a purple non-sulfur phototrophic bacterium, Rhodopseudomonas species No. 7 by a polymerase chain reaction (PCR) based method. The deduced products of dnaK (631 amino acids) and dnaJ (379 amino acids) were 67% and 56% identical to the respective Escherichia coli gene products. The functions of DnaK and DnaJ could be confirmed by complementation of the respective E. coli mutants.

Impact of Helicobacter pylori infection on gastric cancer incidence in a general Japanese population: the Hisayama study.

BACKGROUND: Several nested case-control studies have reported the potentially causal relationship between Helicobacter pylori infection and the development of gastric cancer. However, there has been no prospective study evaluating this issue. The purpose of this study is to examine the impact of H pylori infection on gastric cancer occurrence in a general Japanese population (Hisayama, Japan) stratified according to sex, using a prospective study design. METHODS: A total of 2602 subjects aged 40 years or older (1070 men; mean age, 57 years; 1532 women; mean age, 59 years) without a history of gastrectomy or gastric cancer were classified according to the status of the serum IgG antibodies to H pylori and observed prospectively for 9 years from 1988. RESULTS: Infection of H pylori was more common in men (71.5%) than in women (62.5%; P<.001). The age-adjusted incidence of gastric cancer for men (5.3 per 1000 person-years) was 4-fold higher than that for women (1.3; P<.001). In men, the age-adjusted incidence of gastric cancer was significantly higher in the subjects with H pylori infection than in those without it (6.2 vs 2.5; relative risk, 2.59 [95% confidence interval, 1.03-6.50]), whereas no significant difference was observed in women (1.2 vs 1.1; relative risk, 0.99 [95% confidence interval, 0.36-2.68]). These results were similar even after controlling for other risk factors in multivariate analysis. It was estimated that 40.1% of gastric cancers for men in this cohort were attributable to H pylori infection. CONCLUSION: A significant relationship exists between infection with H pylori and subsequent occurrence of gastric cancer for men but not for women in this Japanese population.

Cloning and analysis of a cDNA encoding a two-domain hemoglobin chain from the water flea Daphnia magna.

A cDNA encoding a two-domain hemoglobin (Hb) chain of Daphnia magna was cloned and its nucleotide (nt) sequence of 1261 bp was determined. The nt sequence contained 74 bp of the leader sequence, 1047 bp of an open reading frame (ORF), and 119 bp of the 3'-untranslated region (UTR), excluding the polyadenylation tail. A sequence, AATACA, located 24 bp upstream from the polyA sequence was considered to be a polyadenylation signal. cDNA-derived amino acid (aa) sequence revealed that D. magna Hb chain is synthesized as a secretory precursor with a signal peptide of 18 aa. Mature D. magna Hb chain consists of 330-aa residues with a calculated molecular weight of 36227, which is composed of two large repeated domains, domain 1 and 2. Several key aa that are invariant in all or most of other Hb and required for functional heme-binding are conserved in each of the two domains. The N-terminal extension (pre-A segment) of domain 1 was unusually long and contained an unusual threonine-rich sequence. The homology between the aa sequences of the two domains (24% identity) was much lower than that observed in other two-domain Hb chains from clams or nematode. Hb mRNA level in D. magna reared under low oxygen concentration was more than 12 times higher than that in D. magna reared with sufficient aeration, indicating that the expression of Hb gene is regulated by mRNA level.

Two-domain hemoglobin gene of the water flea Moina macrocopa: duplication in the ancestral Cladocera, diversification, and loss of a bridge intron.

Two cDNAs encoding the two-domain hemoglobin (Hb) chains of a crustacean Cladocera, Moina macrocopa, were cloned and their nucleotide (nt) sequences were determined. The amino acid (aa) sequences of both the gene products deduced from the nt sequences consisted of 348 residues and showed 98% identity with each other. These sequences together with the NH(2)-terminal aa sequences of the Hb chains determined after separation by two-dimensional gel electrophoresis showed that the Hb chains are synthesized as a secretory precursor with a signal peptide of 17 aa residues. The aa sequences of M. macrocopa Hb chains shared the following features with those of Daphnia Hb chains. Firstly, the signal peptide is followed by an NH(2)-terminal extension containing a threonine-rich sequence that might play a role in the multimerization of subunit chains. Secondly, the identity between the aa sequences of the first and second domains is exceptionally low. These facts suggest that duplication of the cladoceran Hb gene occurred before the divergence of families Moinidae and Daphniidae. Analysis of genomic DNA showed that the M. macrocopa Hb genes consist of two large repeated regions, encoding the first and second domains of Hb chains, respectively. The intron-exon organization of the first region of the M. macrocopa Hb genes was similar to that found in the Daphnia Hb genes, having the three-exon, two-intron structure characteristic of animal Hb genes. However, the intron bridging the two regions and the most downstream intron in the second region were missing in the Moina genes, providing a new example of intron loss. The following elements in the 5' flanking region were conserved in the Moina and Daphnia genes: (1) TATAAA, a typical TATA box sequence accompanied by a downstream sequence, GAAXAGCATCAGTT (the fourth residue X was G or A in Daphnia and absent in Moina); (2) CCAAT boxes, located upstream of the TATA box; (3) the binding sites for HIF-1 and GATA-1, also located upstream of the TATA box, that may be responsible for up-regulation of the cladoceran Hb genes under hypoxia.

Nucleotide sequence and expression in Escherichia coli of cDNA of swine pepsinogen: involvement of the amino-terminal portion of the activation peptide segment in restoration of the functional protein.

A clone, pSPcA2, which carries the full-length swine pepsinogen cDNA was isolated. The coding sequence comprised the signal peptide [15 amino acids (aa)], the activation peptide segment (44 aa) and mature pepsin (327 aa). The deduced amino acid sequence agrees with the published sequence with two exceptions. Asparagine instead of aspartate is present at aa positions 19 and 308. Two types of plasmids, pAS and pUCtacSPc series, were constructed for expressing swine pepsinogen cDNA. These plasmids directed the synthesis of polypeptides which were detected by employing an antibody to swine pepsinogen. However, all the polypeptides formed aggregates and showed no acid protease activity. Only the protein directed by pAS5 regained the acid protease activity after renaturation procedures. The activity was completely inhibited by pepstatin. Furthermore, the renatured pAS5 protein was spontaneously converted to pepsin under acidic conditions. The presence of Arg-8 in the activation peptide segment appears important for the stabilization of the pepsinogen molecule.