The c-axis resistivity (p, ) and its temperature dependence of highly oriented pyrolytic graphite have been studied in connection with the characteristic stacking-fault structure. In order to account for the observations, the pioneering theory of Ono on the tunneling conduction through the stacking-fault planes is reformulated using the concept of effective fault spacing. It is proposed further to add two mechanisms to the Ono theory; one is interlayer charge transfer through the impurity-assisted hopping of carriers similar to that previously considered for graphite intercalation compounds, and the other is thermal excitation of carriers across the low potential barrier formed on each fault plane. All the data have been satisfactorily reproduced by the curve fitting based on the formula consisting of these three conduction components. Also, the change of p, in the presence of high pressure is pointed out to be qualitatively explainable in terms of the tunneling associated with the pressure dependence of Slonczewski-Weiss band parameters.

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A moderately halophilic actinomycete was isolated from a soil sample obtained from Death Valley, Calif. The morphological and chemical properties of the isolate conform to the characteristics of the genus Actinopolyspora, which until now has contained a single species, Actinopolyspora halophila. Our isolate can be distinguished from A . halophila on the basis of physiological and biochemical properties and DNA relatedness data. Therefore, we propose a new species for this strain, Actinopolyspora rnortivallis; the type strain is strain HS-1 (= JCM 7550).Halophilic microorganisms can be conveniently grouped according to their requirements for NaCl for growth (10). Slightly halophilic organisms in marine environments can grow in the presence of 2 to 3% NaCl. The moderate halophiles grow over a much wider NaCl concentration range (5 to 20%, wtlvol). The extreme halophiles, including the well-known halobacteria and halococci, are able to grow in saturated NaCl and unable to grow in the presence of NaCl concentrations lower than 12%. Gochnauer et al. (6) described a new extremely halophilic actinomycete, Actinopolyspora halophila, which was isolated as a contaminant of a culture medium containing 25% NaCl. This species could grow in saturated NaCl and required a minimum NaCl concentration of 10 to 12.5% for growth. During the course of screening for antibiotics, a moderately halophilic actinomycete that produced nucleoside antibiotics was isolated from salty soil obtained from Death Valley, Calif. This isolate grew in media containing a wide range of NaCl concentrations (5 to 25%, wtlvol), in contrast to the extremely halophilic strain, which survived only in solutions containing more than 10% (wthol) NaC1. On the basis of its morphological and chemical properties, we assign this isolate to the genus Actinopolyspora, and we propose a new species, Actinopolyspora mortivallis, on the basis of physiological and biochemical characteristics and levels of DNA-DNA homology. MATERIALS AND METHODSStrain HS-lT (T = type strain) was isolated from a soil sample collected at Death Valley, Calif. The following strains were used for comparison with strain HS-lT: Actinopolyspora halophila ATCC 27976T, Amycolata autotrophica JCM 434gT, Amycolatopsis orientalis JCM 4600T, Pseudonocardia thermophila JCM 3095T, Saccharomonospora viridis JCM 3036T, Saccaropolyspora hirsuta JCM 3170T, * Corresponding author. t Present address: Technological Development Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Nakagawara, Shinkawacho, Nishikasugai-gun, Aichi, Japan.$ Present address: Department of Bio-Engineering, Tokyo Institute of Technology, Tokyo, Japan.and Saccharopolyspora rectivirgula JCM 3057T. In a DNA-DNA hybridization experiment, Nocardia asteroides JCM 3384T was also used as a negative control.For morphological observations, the strains were grown on complex medium agar (16) and potato-dextrose agar at 45°C for 4 weeks and examined by using light microscopy and scanning electron microscopy. For scanning electron microscopy, an a...

Background: Effective new anti-human cytomegalovirus (HCMV) agents and regimens need to be developed. We examined the anti-HCMV properties of crude extract (True World Extract of Bambuseae sasa [TWEBS]) and five compounds (p-coumaric acid, 3-hydroxy-4-methoxyben-zaldehyde [vanillin], p-hydroxybenzaldehyde, 3-hydroxypyridine and 4',5,7-trihydroxy-3',5'-dimethoxyflavone [tricin]), isolated from Sasa albo-marginata, a bamboo known in Japan as Sasa. Methods: Among TWEBS and five compounds screened in a plaque reduction assay, four showed anti-HCMV activity in the MRC-5 human embryonic fibroblast cell line. The anti-HCMV mechanisms of the TWEBS was examined by western blot analysis using primary antibody specific for an immediate early (IE) antigen of HCMV, for a structural late antigen of HCMV and for β-actin. Results: Treatment of cells with ⩾0.001% of TWEBS inhibited the observable cytopathic effects of HCMV on infected cells. Western blot analysis demonstrated that TWEBS decreased the expression of IE antigen and late antigen of HCMV in the infected cells. Next, we examined the anti-HCMV properties of five compounds isolated from TWEBS. In a viral plaque reduction assay, tricin showed dose-dependent inhibitory properties with a 50% effective concentration of 0.17 µug/ml (selective index =1,205.8). Conclusions: The hot water extract (TWEBS) of Sasa albo-marginata, with tricin isolated from it, has anti-HCMV activity in MRC-5 cells. TWEBS and/or tricin are a novel compound with potential anti-HCMV activity. Future studies should evaluate these findings in vivo.

The 52-kDa protein, EshA, whose expression is controlled developmentally, is produced during the late growth phase of Streptomyces spp. We found that disruption of the eshA gene, which encodes the EshA protein, abolishes the aerial mycelium formation and streptomycin production in Streptomyces griseus when grown on an agar plate. The eshA disruptant KO-390 demonstrated a reduced amount of expression of the transcriptional activator strR, thus accounting for the failure to produce streptomycin. KO-390 was found to accumulate deoxynucleoside triphosphates at high levels, including dGTP, at late growth phase. The accumulation of dGTP was a cause for the impaired ability of KO-390 to produce aerial mycelium, because the ability to form aerial mycelium was completely repaired by addition of decoyinine, an inhibitor of GMP synthetase. The accumulation of dNTP in KO-390 coincided with a reduced rate of DNA synthesis. The developmental time frame of these phenomena in KO-390 matched a burst of EshA expression in the wild-type strain. In contrast to S. griseus, the eshA disruption did not affect the ability for Streptomyces coelicolor to form aerial mycelium and did not result in the aberrant accumulation of dNTP accompanied by arrest of DNA synthesis, implying qualitative differences in addition to quantitative differences between the two EshA proteins. We propose that the S. griseus EshA protein somehow positively affects (or regulates) the replication of DNA in wild-type cells at late growth phase but leads to aberrant phenotypes in mutant cells due to the disturbed DNA replication. The EshA protein was found to exist as a multimer (ϳ20-mers) creating a cubic-like structure with a diameter of 27 nm and located predominantly in cytoplasm.