The ixodid tick Ixodes persulcatus is the most important vector of Lyme disease in Japan. Most spirochete isolates obtained from I. persulcatus ticks have been classified as Borrelia burgdorferi sensu lato because of their genetic, biological, and immunological characteristics. However, we found that a small number of isolates obtained from I. persulcatus contained a smaller 38-kDa endoflagellar protein and single 23s-5s rRNA gene unit. Representative isolate HT31T (T = type strain) had the same 23s rRNA gene physical map as Borrelia turicatae. The DNA base composition of strain HT31T was 28.6 mol% G+C. DNA-DNA hybridization experiments revealed that strain HT31T exhibited moderate levels of DNA relatedness (24 to 51%) with Borrelia hemsii, B. turicatae, Borrelia parkeri, and Borrelia coriaceae. However, the levels of DNA reassociation with the previously described Lyme disease borreliae (B. burgdorferi, Borrelia garinii, and Borrelia afielii) were only 8 to 13%. None of the previously described species examined exhibited a high level of DNA relatedness with strain HT31T. In addition, the 16s rRNA gene sequence (length, 1,368 nucleotides) of strain HT31T was determined and aligned with the 16s rRNA sequences of other Borrelia species. Distance matrix analyses were performed, and a phylogenetic tree was constructed. The results showed that isolate HT31T is only distantly related to both previously described Lyme disease borreliae and relapsing fever borreliae. Thus, the spirochetes isolated from I. persulcatus and closely related isolates should be classified as members of a new Borrelia species. We propose the name Borrelia rniyamotoi sp. nov. for this spirochete; strain HT31 is the type strain.We previously demonstrated the usefulness of a restriction fragment length polymorphism (RFLP) ribotyping system based on the 23s-5s rRNA gene repetition in Borrelia burgdorferi sensu lato associated with Lyme disease (14, 32). Many spirochete isolates were examined with our RFLP ribotyping system by using rRNA gene probes. The strains isolated in the United States and Europe were placed into three distinct RFLP groups. The North American isolates clustered in ribotype group I (B. burgdo$eri sensu stricto), and the European isolates were placed in ribotype groups I and I1 (Borrelia garinii) and ribotype group I11 (Borrelia afielii). These groups are completely consistent with the three previously described Lyme disease agent species (2,7,18). Our findings also showed that there are no B. burgdorferi sensu stricto representative strains in Japan and that some Japanese isolates belong to ribotype groups I1 and 111. In addition, most of the Japanese isolates produced RFLP patterns that were quite distinct from those of the North American and European isolates and were tentatively classified as ribotype group IV strains (14). Borrelia japonica is carried by Ixodes ovatus ticks, and it is thought that this microorganism is restricted to Japan. Moreover, some atypical spirochetes have been isolated in United States and Europe (...

meso-Aryl-substituted [28]hexaphyrins(1.1.1.1.1.1) have been examined by (1)H, (13)C, and (19)F NMR spectroscopies, UV-vis absorption spectroscopy, magnetic circular dichroism spectroscopy, and single-crystal X-ray diffraction analysis. All of these data consistently indicate that [28]hexaphyrins(1.1.1.1.1.1) in solution at 25 degrees C exist largely as an equilibrium among several rapidly interconverting twisted Möbius conformations with distinct aromaticities, with a small contribution from a planar rectangular conformation with antiaromatic character at slightly higher energy. In the solid state, [28]hexaphyrins(1.1.1.1.1.1) take either planar or Möbius-twisted conformations, depending upon the meso-aryl substituents and crystallization conditions, indicating a small energy difference between the two conformers. Importantly, when the temperature is decreased to -100 degrees C in THF, these rapid interconversions among Möbius conformations are frozen, allowing the detection of a single [28]hexaphyrin(1.1.1.1.1.1) species having a Möbius conformation. Detailed analyses of the solid-state Möbius structures of compounds 2b, 2c, and 2f showed that singly twisted structures are achieved without serious strain and that cyclic pi-conjugation is well-preserved, as needed for exhibiting strong diatropic ring currents. Actually, the harmonic-oscillator model for aromaticity (HOMA) values of these structures are significantly large (0.85, 0.69, and 0.71, respectively), confirming the first demonstration of stable Möbius aromatic systems consisting of free-base expanded porphyrins without the assistance of metal coordination.

Abstract:The effect of ă-toxin, a thermolysin-like metalloprotease of Clostridium perfringens, on the inac-