Variability in microbial community and venting chemistry in a sediment-hosted backarc hydrothermal system: Impacts of subseafloor phase-separation

Phase-separation and -segregation (boiling/distillation of subseafloor hydrothermal fluids) represent the primary mechanisms causing intra-field variations in vent fluid compositions. To determine whether this geochemical process affects the formation of microbial communities, we examined the microbial communities at three different vent sites located within a few tens meters of one another. In addition to chimney structures, colonization devices capturing subseafloor communities entrained by the vent fluids were studied, using culture-dependent and -independent methods. Microbiological analyses demonstrated the occurrence of distinctive microbial communities in each of the hydrothermal niches. Within a chimney structure, there was a transition from a mixed community of mesophiles and thermophiles in the exterior parts to thermophiles in the interior. Beside the transition within a chimney structure, intra-field variations in microbial communities in vent fluids were apparent. Geochemical analysis demonstrated that different vent fluids have distinctive end-member compositions as a consequence of subseafloor phase-separation and -segregation, which were designated gas-depleted, normal and gas-enriched fluids. In comparison to gas-depleted and normal fluids, gas-enriched fluids harbored more abundant chemolithoautotrophs with gaseous component-dependent energy metabolism, such as hydrogenotrophic methanogenesis. Subseafloor phase-separation and -segregation may play a key role in supplying energy and carbon sources to vent-associated chemolithoautotrophs and subvent microbial communities.

Sulfurihydrogenibium yellowstonense sp. nov., an extremely thermophilic, facultatively heterotrophic, sulfur-oxidizing bacterium from Yellowstone National Park, and emended descriptions of the genus Sulfurihydrogenibium, Sulfurihydrogenibium subterraneum and Sulfurihydrogenibium azorense

A novel thermophilic, sulfur-oxidizing Gram-negative bacterium, designated strain SS-5T, was isolated from the Calcite Hot Springs in Yellowstone National Park, USA. The cells were motile rods (1·2–2·8 μm long and 0·6–0·8 μm wide). The new isolate was a facultative heterotroph capable of using elemental sulfur or thiosulfate as an electron donor and O2 (1–18 %; optimum 6 %, v/v) as an electron acceptor. Hydrogen did not support growth. The isolate grew autotrophically with CO2. In addition, strain SS-5T utilized various organic carbon sources such as yeast extract, tryptone, sugars, amino acids and organic acids. Growth was observed between 55 and 78 °C (optimum 70 °C; 3·5 h doubling time), pH 6·0 and 8·0 (optimum pH 7·5), and 0 and 0·6 % (w/v) NaCl (optimum 0 %). The G+C content of the genomic DNA was 32 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate was a member of the genus Sulfurihydrogenibium. On the basis of the physiological and molecular characteristics of the new isolate, we propose the name Sulfurihydrogenibium yellowstonense sp. nov. with SS-5T (=JCM 12773T=OCM 840T) as the type strain. In addition, emended descriptions of the genus Sulfurihydrogenibium, Sulfurihydrogenibium subterraneum and Sulfurihydrogenibium azorense are proposed.

Distribution, phylogenetic diversity and physiological characteristics of epsilon-Proteobacteria in a deep-sea hydrothermal field

Epsilon-Proteobacteria is increasingly recognized as an ecologically significant group of bacteria, particularly in deep-sea hydrothermal environments. In this study, we studied the spatial distribution, diversity and physiological characteristics of the epsilon-Proteobacteria in various microbial habitats in the vicinity of a deep-sea hydrothermal vent occurring in the Iheya North field in the Mid-Okinawa Trough, by using culture-dependent and -independent approaches. The habitats studied were inside and outside hydrothermal plume, and annelid polychaete tubes. In addition, we deployed colonization devices near the vent emission. The polychaete tubes harboured physiologically and phylogenetically diverse microbial community. The in situ samplers were predominantly colonized by epsilon-Proteobacteria. Energy metabolism of epsilon-Proteobacteria isolates was highly versatile. Tree topology generated from the metabolic traits was significantly different (P = 0.000) from that of 16S rRNA tree, indicating current 16S rRNA gene-based analyses do not provide sufficient information to infer the physiological characteristics of epsilon-Proteobacteria. Nevertheless, culturability of epsilon-Proteobacteria in various microbial habitats differed among the phylogenetic subgroups. Members of Sulfurimonas were characterized by the robust culturability, and the other phylogenetic subgroups appeared to lose culturability in seawater, probably because of the sensitivity to oxygen. These results provide new insight into the ecophysiological characteristics of the deep-sea hydrothermal vent epsilon-Proteobacteria, which has never been assessed by comparative analysis of the 16S rRNA genes.

Identification of a gene induced in conjugation-promoted cells of toxic marine dinoflagellatesAlexandrium tamarenseandAlexandrium catenellausing differential display analysis

Marine dinoflagellates Alexandrium tamarense and Alexandrium catenella produce toxins that cause paralytic shellfish poisoning (PSP). A detailed mechanism of encystment is necessary for a better understanding of bloom dynamics and the toxic effect of these organisms. In this study, a cDNA that was up-regulated in conjugation-promoted cells at encystment was identified using differential display. It encoded a polypeptide of 195 amino acids with a molecular weight of 20,900 Da. The deduced amino acid sequence of this cDNA showed 62% similarity with the polypeptide encoded by SPS19, a gene that is activated specifically during spore maturation and spore wall formation in Saccharomyces cerevisiae. Therefore, the cDNA obtained was termed an SPS19 homolog in this study. The expression levels of the SPS19 homolog were highest immediately after the promotion of conjugation and decreased sequentially later, a pattern similar to that of SPS19 in the sporulation of S. cerevisiae in terms of the time of induction and the duration of expression. These similarities between the SPS19 homolog and SPS19 suggested that the putative function of the SPS19 homolog might be an involvement in encystment. RT-PCR showed that the expression of the SPS19 homolog was highest in conjugation-promoted cells but low in vegetative cells. The SPS19 homolog was believed to be expressed constantly in order for cells to respond rapidly to environmental changes and ensure encystment. Characterization of the identified gene might help in understanding the mechanism of encystment.

Species-specific detection and quantification of toxic marine dinoflagellates Alexandrium tamarense and A. catenella by Real-time PCR assay

A Real-time polymerase chain reaction (PCR) assay was designed and evaluated for rapid detection and quantification of the toxic dinoflagellates Alexandrium catenella and A. tamarense, which cause paralytic shellfish poisoning. Two sets of PCR primers and fluorogenic probes targeting these two species were derived from the sequence of 28S ribosomal DNA. PCR specificity was examined in closely related Alexandrium spp. and many other microalgae. A. catenella-specific primers and probe detected the PCR amplification only from A. catenella strains, and nonspecific signals were not detected from any microalgae. Also, A. tamarense-specific primers and probe also detected the targeted species, suggesting the strict species specificity of each PCR. This assay could detect one cell of each species, showing its high sensitivity. Moreover, using the developed standard curves, A. tamarense and A. catenella could be quantified in agreement with the quantification by optical microscopy. The performance characteristics of species specificity, sensitivity, and rapidity suggest that this method is applicable to the monitoring of the toxic A. tamarense and A. catenella.

Evaluation of clinical and serological data from Taenia solium cysticercosis patients in eastern Inner Mongolia Autonomous Region, China

Neurocysticercosis (NCC) is one of the major causes of neurological disease in China. ELISA and immunoblotting using glycoproteins purified by preparative isoelectric focusing were used to detect human cysticercosis in Tongliao area, Inner Mongolia, China in 1998. Approximately 89% (39 of 44 inpatients and outpatients with suspected NCC at Tongliao City Hospital) were residents of Inner Mongolia. About 53% were male and 77% were of working age (18-59 years), and 32% were farmers. Immunoblotting and ELISA showed a high correlation. Of the 44 patients, 31 positive by cerebral computed tomography (CT) scan were confirmed serologically to have cysticercosis. In the ELISA, patients with no lesions by CT scan had lower OD values, similar to those of normal serum. These findings confirm that both ELISA and immunoblotting assays are sufficiently sensitive to detect asymptomatic or symptomatic cysticercosis patients.

Cytochromeaa3in facultatively aerobic and hyperthermophilic archaeonPyrobaculum oguniense

We partially purified and characterized the cytochrome aa3from the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense. This cytochrome aa3showed oxygen consumption activity with N, N, N′, N′-tetramethyl-1,4-phenylenediamine and ascorbate as substrates, and also displayed bovine cytochrome c oxidase activity. These enzymatic activities of cytochrome aa3were inhibited by cyanide and azide. This cytochrome contained heme As, but not typical heme A. An analysis of trypsin-digested fragments indicated that 1 subunit of this cytochrome was identical to the gene product of subunit I of the SoxM-type heme – copper oxidase (poxC). This is the first report of a terminal oxidase in hyperthermophilic crenarchaeon belonging to the order Thermoproteales.Key words: aerobic respiratory chain, terminal oxidase, Archaea, hyperthermophile, Pyrobaculum.

I-ApeKI [corrected]: a novel intron-encoded LAGLIDADG homing endonuclease from the archaeon, Aeropyrum pernix K1

Over 50 introns have been reported in archaeal rRNA genes (rDNAs), a subset of which nests putative homing endonuclease (HEase) genes. Here, we report the identification and characterization of a novel archaeal LAGLIDADG-type HEase, I-ApeI, encoded by the ApeK1.S908 intron within the 16S rDNA of Aeropyrum pernix K1. I-ApeI consists of 222 amino acids and harbors two LAGLIDADG-like sequences. It recognizes the 20 bp non-palindromic sequence 5′-GCAAGGCTGAAAC↓TTAAAGG and cleaves target DNA to produce protruding tetranucleotide 3′ ends. Either Mn²⁺ or Co²⁺ can be substituted for Mg²⁺ as a cofactor in the cleavage reaction. Of the 20 bases within the minimal recognition site, 7 are essential for cleavage and are located at positions proximal to the cleavage sites.

Hydrogenivirga caldilitoris gen. nov., sp. nov., a novel extremely thermophilic, hydrogen- and sulfur-oxidizing bacterium from a coastal hydrothermal field

A novel extremely thermophilic, hydrogen- and sulfur-oxidizing bacterium, designated strain IBSK3(T), was isolated from a coastal hot spring in Ibusuki, Kagoshima Prefecture, Japan. The cells were motile, straight to slightly curved rods (1.2-3.0 microm long and 0.3-0.4 microm wide). Strain IBSK3(T) was an obligate chemolithoautotroph growing by respiratory nitrate reduction with H(2), forming N(2)O as an end product. Low concentrations of O(2) (0.4-7.7 %, v/v; optimum 2.0 %, v/v) could serve as an alternative electron acceptor to growth. In addition, strain IBSK3(T) was able to utilize elemental sulfur as a sole electron donor with either nitrate or low concentrations of O(2) as an electron acceptor. Growth was observed between 55 and 77.5 degrees C (optimum 75 degrees C; 2 h doubling time), pH 5.5 and 8.3 (optimum pH 6.5-7.0), and in the presence of 0.5 and 4.0 % NaCl (optimum 2.0 %). The G+C content of the genomic DNA was 49.2 mol%. On the basis of 16S rRNA gene sequence analysis, strain IBSK3(T) belonged to the family Aquificaceae, but it only demonstrated a distant phylogenetic relationship with any recognized species within the family (sequence similarity was less than 92 %). On the basis of the physiological and molecular characteristics of the novel isolate, a new genus and novel species are proposed: the type strain of Hydrogenivirga caldilitoris gen. nov., sp. nov. is IBSK3(T) (=JCM 12173(T)=ATCC BAA-821(T)).

Development of molecular identification method for genus Alexandrium (Dinophyceae) using whole-cell FISH

We have developed a method to identify species in the genus Alexandrium using whole-cell fluorescent in situ hybridization with FITC-labeled oligonucleotide probes that target large subunit ribosomal rRNA molecules. The probes were designed based on the sequence of the rDNA D1-D2 region of Alexandrium species. DNA probes specific for toxic A. tamarense and A. catenella and nontoxic A. affine, A. fraterculus, A. insuetum, and A. pseudogonyaulax, respectively, were applied to vegetative cells of all above Alexandrium species to test the sensitivity of the probes. Each DNA probe hybridized specifically with vegetative cells of the corresponding Alexandrium species and showed no cross-reactivity to noncorresponding Alexandrium species. In addition, no cross-reactivity of the probes was observed in experiments using concentrated natural seawater samples. The TAMAD2 probe, which is highly specific to A. tamarense, a common toxic species in Korean coastal waters, provides a simple and reliable molecular tool for identification of toxic Alexandrium species.

Nitratiruptor tergarcus gen. nov., sp. nov. and Nitratifractor salsuginis gen. nov., sp. nov., nitrate-reducing chemolithoautotrophs of the ε-Proteobacteria isolated from a deep-sea hydrothermal system in the Mid-Okinawa Trough

Two novel denitrifying bacteria, designated strains MI55-1Tand E9I37-1T, were isolated from deep-sea hydrothermal vent chimney structures at the Iheya North hydrothermal field in the Mid-Okinawa Trough, Japan. Both isolates were strict chemolithoautotrophs growing by respiratory nitrate reduction with H2, forming N2as a metabolic product. Oxygen (at low concentrations) could serve as an alternative electron acceptor for growth of the isolates. Growth of strain MI55-1Twas observed at temperatures between 40 and 57 °C (optimum, 55 °C; doubling time, 2 h), at pH values between 5·4 and 6·9 (optimum, pH 6·4) and in the presence of between 1·5 and 4·0 % (w/v) NaCl (optimum, 2·5 %). Growth of strain E9I37-1Twas observed at temperatures between 28 and 40 °C (optimum, 37 °C; doubling time, 2·5 h), at pH values between 5·6 and 7·6 (optimum, pH 7·0) and in the presence of between 1·5 and 3·5 % (w/v) NaCl (optimum, 3·0 %). The G+C contents of the genomic DNA of strains MI55-1Tand E9I37-1Twere 29·6 and 35·5 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains MI55-1Tand E9I37-1Tbelonged to groups A and F of theε-Proteobacteria, but that they had distant phylogenetic relationships with any species, within the phylogenetic groups, that had validly published names (sequence similarities were less than 91 %). On the basis of the physiological and molecular characteristics of the novel isolates, it is proposed that they should each be classified in a novel genus:Nitratiruptor tergarcusgen. nov., sp. nov., with MI55-1T(=JCM 12459T=DSM 16512T) as the type strain, andNitratifractor salsuginisgen. nov., sp. nov., with E9I37-1T(=JCM 12458T=DSM 16511T) as the type strain.

Thioreductor micantisoli gen. nov., sp. nov., a novel mesophilic, sulfur-reducing chemolithoautotroph within the ε-Proteobacteria isolated from hydrothermal sediments in the Mid-Okinawa Trough

A novel mesophilic, hydrogen-oxidizing, sulfur-reducing bacterium, designated strain BKB25Ts-YT, was isolated from hydrothermal sediments at Iheya North in the Mid-Okinawa Trough, Japan. Cells were Gram-negative, motile rods (1·8–2·1 μm long and 0·5–0·7 μm wide). The isolate was a strictly anaerobic chemolithoautotroph capable of using molecular hydrogen as the sole energy source and carbon dioxide as the sole carbon source. Elemental sulfur and nitrate served as electron acceptors, respectively yielding hydrogen sulfide and ammonium. Growth was observed at 20–42 °C (optimum 32 °C; 3 h doubling time), pH 5·0–6·5 (optimum 6·0) and in the presence of 2·0–4·0 % NaCl (optimum 2·5 %) via respiratory S0 reduction with H2. The G+C content of the genomic DNA was 37·2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate represented the first strain for which taxonomic properties have been characterized within the previously uncultivated ε-Proteobacteria Group G. On the basis of the physiological and molecular properties of the novel isolate, the genus name Thioreductor gen. nov. is proposed, with Thioreductor micantisoli sp. nov. as the type species. The type strain is BKB25Ts-YT (=JCM 12457T=DSM 16661T).

Crystallization and preliminary X-ray diffraction analysis of homing endonuclease I-Tsp061I

Two crystal forms, rhombohedral and hexagonal, of a homing endonuclease from Thermoproteus sp. IC-061 (I-Tsp0611) were obtained by the hanging-drop and sitting-drop method, respectively. The hexagonal crystals belong to space group P6(3)22, with unit-cell parameters a = b = 111.4, c = 97.6 A, and diffract to 3.2 A resolution on beamline BL44 at SPring-8 (Harima, Japan). The rhombohedral crystals belong to space group R32, with unit-cell parameters a = b = 95.4, c = 192.9 A, and diffract to 2.7 A resolution using a Cu Kalpha rotating-anode generator with an R-AXIS VII detector. The crystal asymmetric unit contained one protein molecule and the solvent contents of the two crystal forms were estimated to be 68.3 and 67.6% by volume, respectively.

Aeropyrum camini sp. nov., a strictly aerobic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney

A novel hyperthermophilic archaeon, designated strain SY1T, was isolated from a deep-sea hydrothermal vent chimney sample collected from the Suiyo Seamount in the Izu-Bonin Arc, Japan, at a depth of 1385 m. The cells were irregular cocci (1·2 to 2·1 μm in diameter), occurring singly or in pairs, and stained Gram-negative. Growth was observed between 70 and 97 °C (optimum, 85 °C; 220 min doubling time), pH 6·5 and 8·8 (optimum, pH 8·0), and salinity of 2·2 and 5·3 % (optimum, 3·5 %). It was a strictly aerobic heterotroph capable of growing on complex proteinaceous substrates such as yeast extract and tryptone. The G+C content of the genomic DNA was 54·4 mol%. Phylogenetic analysis based on the 16S rDNA sequence of the isolate indicated that the isolate was closely related toAeropyrum pernixstrain K1T. However, no significant genetic relatedness was observed between them by DNA–DNA hybridization. On the basis of the molecular and physiological traits of the new isolate, the nameAeropyrum caminisp. nov. is proposed, with the type strain SY1T(=JCM 12091T=ATCC BAA-758T).

Recent advances in basic and applied science for the control of taeniasis/cysticercosis in Asia

Detection of seven specific bands by immunoblot (IB) using glycoproteins (GPs) purified by lentil-lectin affinity chromatography has been the gold-standard for neurocysticercosis (NCC) serodiagnosis since 1989. However, due to the presence of contaminants, it was impossible to apply the GPs to ELISA. Our group at Asahikawa Medical College (AMC) succeeded in purifying the GPs by preparative isoelectric focusing; these higher quality GPs were suitable for ELISA. Based on the results of both IB and ELISA testing, developed at AMC for a field survey in Irian Jaya, it became evident that that area had pandemic NCC. We found many NCC patients, pigs full of cysts, and one dog infected with two cysts: these findings were based on serology. Recently, we conducted another survey to detect of the worm carriers of T. solium. Three of the 38 local people were positive by copro-antigen specific to Taenia species; these three patients expelled segments of Taenia spp and these were confirmed as those of T. solium by mitochondrial DNA analysis. When viable eggs of any taeniid species could be obtained, they can be developed into metacestodes in NOD-scid mice; it then becomes possible to analyze morphological dynamics, metacestode antigenicity, the efficacy of new metacestocidal drugs, and mitochondrial DNA. Mitochondrial DNA analysis of the specimens obtained in Irian Jaya was compared with that of other isolates worldwide. T. solium is now divided into two genotypes: the Asian type, and the Africa-American type. Some aspects of the pathological differences between the Asian and Africa-American types and the antigenic components of these two types are discussed.

Balnearium lithotrophicum gen. nov., sp. nov., a novel thermophilic, strictly anaerobic, hydrogen-oxidizing chemolithoautotroph isolated from a black smoker chimney in the Suiyo Seamount hydrothermal system

A novel, extremely thermophilic bacterium, designated strain 17S(T), was isolated from a deep-sea hydrothermal vent chimney at the Suiyo Seamount in the Izu-Bonin Arc, Japan. The cells were rods with no apparent motility, most of which were narrow in the middle in the exponential-growth phase and had several polar flagella at both ends. Growth was observed between 45 and 80 degrees C (optimum temperature, 70-75 degrees C; doubling time, 80 min) and between pH 5.0 and 7.0 (optimum pH, 5.4). The isolate was a strictly anaerobic chemolithoautotroph that was capable of using molecular hydrogen as its sole energy source and carbon dioxide as its sole carbon source. Elemental sulfur (S(0)) was required for growth as an electron acceptor. The G+C content of the genomic DNA was 34.6 mol%. Phylogenetic analysis based on 16S rDNA sequences indicated that the isolate was related to Thermovibrio ruber ED11/3LLK(T) and Desulfurobacterium thermolithotrophum BSA(T), whilst it appeared to be a novel lineage prior to the divergence of these genera. This isolate could also be differentiated from both T. ruber ED11/3LLK(T) and D. thermolithotrophum BSA(T) on the basis of physiological properties. The name Balnearium lithotrophicum gen. nov., sp. nov. is proposed for this isolate (type strain, 17S(T)=JCM 11970(T)=ATCC BAA-736(T)).

Mechanism of thermotolerance induction by split-dose hyperthermia in Deinococcus radiodurans DNA repair deficient mutants

We examined the phenomenon of thermotolerance induction in the radioresistant prokaryote, Deinococcus radiodurans, which was initially exposed to 30 min at 52 degrees C followed by various intervals up to 6 h at 30 degrees C in TGY medium and then re-exposed to 52 degrees C for various periods, i.e., split-dose hyperthermia. This thermotolerance induction was analyzed in DNA repair deficient mutants (strain 302, 251, UVS25, rec30 and KH840) and the wild-type strain MR1. The strain UVS25 is a double mutant for the mtcA and uvsD genes, and strain rec30 is a mutant for the deinococcal recA gene. The induction was suppressed to 1/10 and 1/25 in strains UVS25 and rec30 respectively, as compared with the maximum level in the wild-type strain MR1. However, the induction in strain 302 (mutant for the uvrA gene) was not suppressed. Therefore, we conclude that proteins synthesized during the interexposure interval, i.e., the products of the uvsD (UV endonuclease beta) and recA (RecA protein) genes contribute to the induction of thermotolerance in D. radiodurans.

Differences in tyrosine tRNA identity between Escherichia coli and archaeon, Aeropyrum pernix K1

Recognition sites of tyrosine tRNA for tyrosyl-tRNA synthetase from Escherichia coli and extreme thermophilic archaeon, Aeropyrum pernix K1 were examined using various in vitro transcripts. With respect to the long variable arm in E. coli tyrosine tRNA, some base pairs in length was required for tyrosylation. None of the recognition sites were found in the acceptor stem, except the discriminator base A73 in E. coli tyrosine tRNA. In case of A. pernix tyrosine tRNA, C1-G72 base pair and discriminator base A73 in the acceptor region as well as anticodon were base specifically involved in tyrosylation by A. pernix tyrosyl-tRNA synthetase.

Molecular recognition of threonine tRNA by threonyl-tRNA synthetase from an extreme thermophilic archaeon, Aeropyrum pernix K1

To investigate the recognition sites of tRNA(Thr) for threonyl-tRNA synthetase (ThrRS) from an extreme thermophilic and aerobic archaeon, Aeropyrum pernix K1, threonylation experiments using various in vitro mutant transcripts of tRNA(Thr) were examined. The results indicated that A. pernix ThrRS did recognize the first three base pairs of acceptor stem in addition to the second and the third letters of anticodon of tRNA(Thr), in spite of its N-terminal truncated unique structure. Discriminator base was not involved in recognition by A. pernix ThRS. These determinants were confirmed by the identity switching experiments from the in vitro mutants of A. pernix tRNA(Pro) and tRNA(Asn).

Recognition of tRNA by aminoacyl-tRNA synthetase from hyperthermophilic archaea, Aeropyrum pernix K1

To study the recognition sites of tRNA for archaeal aminoacyl-tRNA synthetase, several aminoacyl-tRNA synthetase genes from hyperthermophilic archaeon, Aeropyrum pernix K1 were cloned and expressed. All the expressed enzymes showed extreme thermostability. Expressed threonyl-tRNA synthetase threonylated not only archaeal (A. pernix and Haloferax volcanii) threonine tRNAs but also Escherichia coli threonine tRNA. However, threonyl-tRNA synthetase from H. volcanii did not threonylate E. coli threonine tRNA.

An archaeal homing endonuclease I-PogI cleaves at the insertion site of the neighboring intron, which has no nested open reading frame

Homing endonucleases (HEs) of the LAGLIDADG family cleave intron/inteinless cognate DNA at, or near, the insertion site (IS) of their own intron/intein. Here, we describe a notable exception to this rule. Two introns, Pog.S1205 (length 32 bp) and Pog.S1213 (664 bp), whose ISs are 8 bp apart, exist within the 16S rRNA gene of the archaeon Pyrobaculum oguniense. Pog.S1213 harbors a nested open reading frame (ORF) encoding a 22 kDa monomeric protein, I-PogI, which contains two LAGLIDADG motifs and has optimal DNA cleavage activity at 90 degrees C. Intriguingly, I-PogI cleaves the Pog.S1205-less substrate DNA in the presence or absence of Pog.S1213. The cleavage site (CS) of I-PogI does not coincide with the IS of Pog.S1213 but with that of Pog.S1205. Thus, I-PogI activity both promotes the homing of its own intron, Pog.S1213, and guarantees co-conversion of the ORF-less intron Pog.S1205.

Distribution of 16S rRNA introns among the family Thermoproteaceae and their evolutionary implications

Novel 16S rRNA introns were detected in four new strains within the family Thermoproteaceae. Pyrobaculum oguniense TE7(T) and Thermoproteus sp. IC-062 housed introns of 32 and 665-668 bp after positions 1205 and 1213 ( Escherichia coli numbering system), respectively. Caldivirga maquilingensis IC-167(T) had two introns of 37 and 140 bp after positions 901 and 908, respectively. Vulcanisaeta distributa IC-065 had a 691-bp intron after position 1391. All the introns larger than 650 bp encoded the LAGLI-DADG type proteins. The intron-encoded proteins of P. oguniense TE7(T) and Thermoproteus sp. IC-062 are cognate with the proteins encoded by introns inserted at the same position in other Pyrobaculum/ Thermoproteus strains and phylotypes. The intron-encoded protein of V. distributa IC-065 is partially related to that of a Pyrobaculum phylotype. A large-scale deletion in the second intron of Caldivirga maquilingensis IC-167(T) is suspected. Based on these newly found introns and hitherto known 16S rRNA introns, the evolutionary movements of the 16S rRNA introns and the encoded LAGLI-DADG type proteins are discussed.

Persephonella hydrogeniphila sp. nov., a novel thermophilic, hydrogen-oxidizing bacterium from a deep-sea hydrothermal vent chimney

A novel thermophilic, hydrogen-oxidizing bacterium, designated 29W(T), was isolated from a deep-sea hydrothermal vent chimney sample collected from the Suiyo Seamount in the Izu-Bonin Arc, Japan, at a depth of 1385 m. The cells were cocci (0.9-1.0 microm in diameter) and straight rods (2.3-2.7 microm long) under static and agitated culture conditions, respectively. The new isolate was an obligate chemolithoautotroph growing by respiratory nitrate reduction with H2, forming N2 as a final product. A very low concentration of O2 (optimum 0.6-0.8%, v/v) was also used as an alternative electron acceptor while reduced sulfur compounds did not serve as electron donors. Anoxic hydrogen-oxidizing growth with nitrate was observed between 50 and 72.5 degrees C (optimum 70 degrees C; 40 min doubling time), pH 5.5 and 7.6 (optimum pH 7.2), and in the presence of 1.5 and 5.0% NaCl (optimum 2.5%). The G + C content of the genomic DNA was 37.3 mol%. Phylogenetic analysis based on 16S rDNA sequences indicated that the isolate was a member of the recently described genus Persephonella in a potential new family within the order Aquificales. On the basis of the physiological and molecular properties of the new isolate, the name Persephonella hydrogeniphila sp. nov. is proposed. The type strain is strain 29W(T) (= JCM 11663(T) = DSM 15103(T)).

Regulation of the aerobic respiratory chain in the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense

The aerobic respiratory chain of Pyrobaculum oguniense is expressed constitutively even under anaerobic conditions. The membranes of both aerobically and anaerobically grown cells show oxygen consumption activity with NADH as substrate, bovine cytochrome c oxidase activity and TMPD oxidase activity. Spectroscopic analysis and haem analysis of membranes of aerobically grown cells show the presence of cytochrome b(559), cytochrome c(551) and haem Op1 containing cytochrome c oxidase in aerobically and anaerobically grown cells, and haem As containing cytochrome c oxidase in aerobically grown cells. The gene clusters of SoxB-type and SoxM-type haem copper oxidase and cytochrome bc complex have been cloned and sequenced and the regulation of these genes was analysed. The Northern blot analysis indicated that the constitutive transcription of the gene cluster of SoxB-type haem-copper oxidase and cytochrome bc complex is observed under both aerobic and anaerobic conditions, and the transcription of the operon of SoxM-type haem-copper oxidase was stimulated under aerobic conditions. Furthermore, the presence of the binding residues for CuA in subunit II of both SoxB- and SoxM-type haem-copper oxidase suggests that these haem-copper oxidases are cytochrome c oxidases.

Evaluation of tongue inspection and serology for diagnosis of Taenia solium cysticercosis in swine: usefulness of ELISA using purified glycoproteins and recombinant antigen

Evaluation of serology using glycoproteins (GPs) purified by preparative isoelectric focusing (pH 8.8) and recombinant chimeric antigen (RecTs) of Taenia solium was carried out using (1) blood samples on filter papers from pigs infected with different doses of eggs of T. solium in Mexico, (2) serum samples from pigs found infected naturally in Vietnam and Ecuador and (3) serum samples from pigs suspected to be infected with T. solium by tongue inspection in Tanzania. Antibody responses (IgG) were detectable in experimentally infected pigs confirmed harbouring 16 or more cysts at necropsy from 30 days after egg inoculation. One of three pigs naturally infected and harbouring 2.5 cysts/kg muscle and most of pigs harbouring=5.0 cysts/kg were also seropositive by ELISA. Although pigs may be infected with other taeniid species such as Taenia hydatigena, pigs harbouring this parasite were negative in ELISA. Approximately, 76 and 78% of sera from pigs having nodule(s) in the tongue (positive tongue inspection) were serologically positive by both ELISA and immunoblot, respectively. Furthermore, approximately 34 and 18% of sera from pigs having no nodules in the tongue (negative tongue inspection) were also seropositive by ELISA and immunoblot, respectively. ELISA using the two antigens was more sensitive than immunoblot and reliable for differentiation of pigs infected with cysticerci of T. solium from those either uninfected or infected with other taeniid species. Pigs without nodule by tongue inspection should be checked serologically in endemic areas.

Isolation and phylogenetic diversity of members of previously uncultivated epsilon-Proteobacteria in deep-sea hydrothermal fields

We report the successful cultivation and partial characterization of novel members of epsilon-Proteobacteria, which have long been recognized solely as genetic signatures of small subunit ribosomal RNA genes (rDNA) from a variety of habitats occurring in deep-sea hydrothermal fields. A newly designed microhabitat designated 'in situ colonization system' was used for enrichment. Based on phylogenetic analysis of the rDNA of the isolates, most of these represent the first cultivated members harboring previously uncultivated phylotypes classified into the Uncultivated epsilon-Proteobacteria Groups A, B, F and G, as well as some novel members of Group D. Preliminary characterization of the isolates indicates that all are mesophilic or thermophilic chemolithoautotrophs using H(2) or reduced sulfur compounds (elemental sulfur or thiosulfate) as an electron donor and O(2), nitrate or elemental sulfur as an electron acceptor. The successful cultivation will enable the subsequent characterization of physiological properties and ecological impacts of a diversity of epsilon-Proteobacteria in the deep-sea hydrothermal environments.

Cysticercosis/taeniasis: recent advances in serological and molecular diagnoses

Serodiagnosis by immunoblot, using recombinant chimeric T. solium antigen and native glycoprotein antigens, has been applied for neurocysticercosis cases. Specific antibodies against both antigens were detected in serum samples from NCC patients involving multiple cysts in the brain, whereas it was not always easy to detect specific antibodies in NCC cases with a solitary cyst or calcified lesion(s). On the other hand, the diagnosis for human taeniasis or worm carriers has been routinely performed by stool examination. In this study, multiplex PCR has been established to differentiate taeniasis using Taenia mitochondrial DNA in fecal samples from worm carriers. Furthermore, the molecular identification of human taeniid cestodes by base excision sequence scanning thymine-base analysis has also been introduced. This method provides four thymine-base peak profiles unique for Asian and American/African genotypes of T. solium, T. saginata and T. asiatica. By comparing thymine base peak profiles, it is possible to differentiate human taeniid cestodes without DNA sequencing. The approaches are powerful tools for the routine diagnosis of taeniasis and the molecular identification of taeniid cestodes.

Marinithermus hydrothermalis gen. nov., sp. nov., a strictly aerobic, thermophilic bacterium from a deep-sea hydrothermal vent chimney

A novel thermophilic marine bacterium, designated strain T1T, was isolated from a deep-sea hydrothermal vent chimney sample collected from the Suiyo Seamount in the Izu-Bonin Arc, Japan, at a depth of 1,385 m. Cells of strain T1T were rod-shaped, occurring in pairs or filamentous, and stained Gram-negative. Growth was observed between 50.0 and 72.5 degrees C (optimum 67.5 degrees C; 30 min doubling time) and at pH 6.25-7.75 (optimum pH 7.00). The isolate absolutely required NaCl, at a concentration of 0.5-4.5% (optimum 30%). It was a strictly aerobic heterotroph capable of growing solely on complex organic substrates such as yeast extract, tryptone and Casamino acids, utilizing glutamate, proline, serine, cellobiose, trehalose, sucrose, acetate and pyruvate as complementary substrates. The G+C content of the genomic DNA was 68.6 mol%. The 16S rRNA gene sequence of the isolate was most similar to those from members of the genus Thermus, but the isolate was distantly related to them at the genus level (<90%). In addition, phylogenetic analysis indicated that the isolate was on a novel lineage, deeply branched prior to divergence of the genus Thermus. On the basis of phylogenetic analysis and physiological traits of the isolate, it should be described as a member of a novel genus distinct from the previously described genus Thermus. The name Marinithermus gen. nov. is proposed, with Marinithermus hydrothermalis gen. nov., sp. nov. as the type species. The type strain of M. hydrothermalis gen. nov., sp. nov. is strain T1T (=JCM 11576T =DSM 14884T).

Dogs as alternative intermediate hosts of Taenia solium in Papua (Irian Jaya), Indonesia confirmed by highly specific ELISA and immunoblot using native and recombinant antigens and mitochondrial DNA analysis

Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific to Taenia solium cysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci of T. solium in the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same as T. solium previously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle of T. solium may be completed not only between humans and pigs but also between humans and dogs.

Molecular variation of Taenia solium in the world

Complete nucleotide sequences of the mitochondrial cytochrome b (Cytb) and cytochrome c oxidase subunit I (CO I) genes from various isolates of Taenia solium were examined. Eleven isolates were analyzed; two isolates from China, two isolates from Indonesia, one isolate each from India, Thailand, Mexico, Ecuador, Peru, Mozambique and Tanzania. In both genes, two isolates from Indonesia shared the same sequences. Similarly, the isolate from Mexico shared same sequences with that from Peru, and the isolate from Mozambique shared same sequences with that from Tanzania. Phylogenetic trees inferred from different mitochondrial genes yielded almost the same topology. Both the UPGMA and NJ-trees were also very similar. These trees indicate that T. solium may be diverged to 2 genetic groups; isolates from Asia form one group and isolates from Africa and Latin America belong to the other. It seems that T. solium prevalent in Africa and in Latin America shares the related origin and has recently been introduced to each area, perhaps with domestic pigs or human.

NOD-scid mouse as an experimental animal model for cysticercosis

The major three species of human taeniid cestodes, Taenia solium, T. saginata and T. saginata asiatica (= T. asiatica) which require humans as the definitive host are still not rare in developing countries. Among these, T. solium is the most serious with medical and economic importance. Neurocysticercosis (NCC) in humans is now recognized as the major cause of neurologic disease in the world. As these human taeniid cestodes obligatory require domestic animals such as swine, cattle and swine as the major intermediate host animals respectively, it is not easy to analyze the basic research in these domestic animals. In this brief review, we introduce experimental animal model for these three species in order to obtain fully developed metacestode stage in severe combined immunodeficiency (scid) mice. Non-obese diabetic scid (NOD-scid) mice are expected to be a satisfactory animal model and to have advantages for analysis by several view points of developmental biology with gene expression throughout development, antigenic homology of cyst fluid of these three species, evaluation of drug efficacy or metacestocidal drug designs, confirmation of unknown taeniid gravid segments for identification based on the morphology and DNA analysis of metacestodes. The animal model is not only available for human Taenia spp but can also be applied to other taeniid cestodes of economic importance or in veterinary parasitology.

Recent advances in serodiagnosis for cysticercosis

Neurocysticercosis (NCC) caused by infection with the larval stage of Taenia solium is an important cause of neurological disease worldwide. Up to the present, many studies on characterizing species-specific antigens of T. solium have been done and several high quality antigens for serodiagnosis are available. Hence the research on serodiagnosis has been shifted to the next phase, stable production of diagnostic antigens using molecular techniques. In order to establish an enzyme-linked immunosorbent assay (ELISA) using recombinant proteins, we carried out molecular cloning and identified four diagnostic antigen candidates (Ag1, Ag1V1, Ag2, and Ag2V1). Recombinant proteins, except Ag2V1, were successfully expressed using an Escherichia coli expression system. Immunoblot analysis using NCC patient sera detected recombinant proteins. But as reactivity to rAg1 was too weak, Ag1 was not suitable for the immunodiagnosis antigen. Therefore Ag1V1 and Ag2 were chosen for ELISA antigens and Ag1V1/Ag2 chimeric protein was expressed. Of 49 serum samples from NCC patients confirmed to be seropositive by immunoblot analysis, 44 (89.7%) were positive by ELISA. Serum samples from patients with other parasitic infections did not recognized Ag1V1/Ag2 chimeric protein. Ag1V1/Ag2 chimeric protein obtained in this study is of value for differential immunodiagnosis.

Differential serodiagnosis of cystic and alveolar echinococcosis using native and recombinant antigens in Japan

Our group at Asahikawa Medical College has established differential serodiagnosis for zoonotic larval cestodiases such as alveolar echinococcosis (AE), cystic echinococcosis (CE) and neurocysticercosis (NCC) using purified specific antigens. In this brief review, we introduce (a) four imported CE cases in Japan, easily identified serologically, (b) most recent advances in serology for differentiation of AE and monitoring of prognosis of AE in Japan. It includes application of affinity purified Em18 and prototype of a recombinant Em18 antigen. Serology using affinity purified Em18 antigens is showing much higher sensitivity for detection of AE cases which are usually undetectable by the ongoing serology for AE authorized in Hokkaido, Japan. As serology for AE, CE or NCC is still not popular in the majority of Asian countries, we expect that this review paper stimulates researchers who are interested in serology or serodiagnosis for these larval cestodiases including AE, CE and NCC.

Heterogeneous yet similar introns reside in identical positions of the rRNA genes in natural isolates of the archaeon Aeropyrum pernix

Some archaeal ribosomal DNA (rDNA) introns carry homing endonuclease-like genes and are therefore assumed to propagate by "intron homing". A previous study demonstrated that three introns are located within the rRNA operon (arnSL) of Aeropyrum pernix strain K1, two of which, Ialpha and Igamma, harbor open reading frames (ORFs) encoding putative LAGLIDADG-type endonucleases. In an effort to understand further the rDNA intron distribution in natural A. pernix populations, 11 A. pernix strains were isolated from marine hydrothermal biotopes, and comparative nucleotide sequence analysis of the arnSL alleles was performed. Of the 11 isolates, eight contained multiple introns, and three patterns of intron insertion were found. Three novel introns, Idelta (62 bp in length), Ivarepsilon (122 bp) and Izeta (57 bp) were identified. They were all ORF-less, but their predicted RNA secondary structure at the exon-intron junctions was consistent with the bulge-helix-bulge motif. The insertion positions and the terminal inverted repeat sequences of Idelta and Izeta were in agreement with those of Ialpha and Igamma, respectively. This suggests that these intron variants were generated by large indels (insertions/deletions) during their evolution.

A phylogenetic hypothesis for the distribution of two genotypes of the pig tapeworm Taenia solium worldwide

Genetic polymorphism was determined among 13 isolates of Taenia solium from various regions using PCR-amplified sequences of 2 mitochondrial genes: cytochrome c oxidase subunit 1 and cytochrome b. The 2 phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia (China, Thailand, Irian Jaya and India) formed a single cluster, whereas the isolates from Latin America (Mexico, Peru, Ecuador, Bolivia and Brazil) combined with those from Africa (Tanzania, Mozambique and Cameroon) to form an additional cluster. These results and historical data of swine domestication, distribution of pigs and colonization suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that the tapeworm of another origin independently spread in Asian countries.

Thermaerobacter nagasakiensis sp. nov., a novel aerobic and extremely thermophilic marine bacterium

A novel, extremely thermophilic bacterium was isolated from a shallow marine hydrothermal vent at depth of 22 m in Tachibana Bay, Nagasaki Prefecture, Japan. Cells were gram-negative, non-spore-forming, motile rods. Growth was observed between 52 and 78 degrees C (optimum 70 degrees C), pH 5 and 8 (optimum pH 7) and 0-4.5% NaCl (optimum 1.0%). The isolate was a strictly aerobic heterotroph utilizing yeast extract and trypticase peptone. The G+C content of the genomic DNA is 69 mol%. Analysis of 16S rDNA sequences indicated that strain Ts1a is closely related to Thermaerobacter marianensis. The differences in physiology and DNA-DNA similarity between strain Ts1a and T. marianensis showed that strain Ts1a represents a new species of Thermaerobacter. The type strain of T. nagasakiensis is strain Ts1a (=JCM11223, DSM 14512).

Three proliferating cell nuclear antigen-like proteins found in the hyperthermophilic archaeon Aeropyrum pernix: interactions with the two DNA polymerases

Proliferating cell nuclear antigen (PCNA) is an essential component in the eukaryotic DNA replication machinery, in which it works for tethering DNA polymerases on the DNA template to accomplish processive DNA synthesis. The PCNA also interacts with many other proteins in important cellular processes, including cell cycle control, DNA repair, and an apoptotic pathway in the domain EUCARYA: We identified three genes encoding PCNA-like sequences in the genome of Aeropyrum pernix, a crenarchaeal archaeon. We cloned and expressed these genes in Escherichia coli and analyzed the gene products. All three PCNA homologs stimulated the primer extension activities of the two DNA polymerases, polymerase I (Pol I) and Pol II, identified in A. pernix to various extents, among which A. pernix PCNA 3 (ApePCNA3) provided a most remarkable effect on both Pol I and Pol II. The three proteins were confirmed to exist in the A. pernix cells. These results suggest that the three PCNAs work as the processivity factor of DNA polymerases in A. pernix cells under different conditions. In Eucarya, three checkpoint proteins, Hus1, Rad1, and Rad9, have been proposed to form a PCNA-like ring structure and may work as a sliding clamp for the translesion DNA polymerases. Therefore, it is very interesting that three active PCNAs were found in one archaeal cell. Further analyses are necessary to determine whether each PCNA has specific roles, and moreover, how they reveal different functions in the cells.

Effects of biotin on glucotoxicity or lipotoxicity in rat pancreatic islets

Biotin (vitamin H) plays an important role as a cofactor in glucose or lipid metabolism. We showed that biotin potentiated glucose-induced insulin release in isolated rat islets, while biotin alone did not affect insulin release. Coculture with biotin in islets for 48 hours significantly enhanced glucose-induced insulin release or islet insulin content. Similarly, preproinsulin or pancreatic/duodenal homeobox-1 (PDX-1) mRNA was also enhanced in islets cultured with biotin for 48 hours. Furthermore, we measured effects of biotin on beta-cell function under glucotoxic or lipotoxic states. In islets cultured with high glucose or palmitate for 48 hours, glucose-induced insulin release or islet insulin content deteriorated. Coculture with biotin significantly restored glucose-induced insulin release or islet insulin content together with the restoration of preproinsulin or PDX-1 mRNA. We conclude that biotin exerts its beneficial effects on beta-cell dysfunction induced by glucose or free fatty acids probably through the enhancement of insulin biosynthesis.

Comparison of the antigenicity of protoscoleces and microvesicles of Echinococcus multilocularis prepared from rats

Rats are known to be relatively resistant to infection with Echinococcus multilocularis. However, when rats are inoculated with the parasite tissues, E. multilocularis proliferates slowly at first but after 6 months the cysts increase in size considerably and contain large numbers of protoscoleces. As rats survive for 18 months or longer, approximately 100 ml of packed protoscoleces can be produced from each rat. A comparison of the antigenicity of the protoscoleces and microvesicles by immunoblot methods showed that both Em18 and Em16 are shared components between both protoscoleces and microvesicles, although the latter have some additional antigenic components. In antigens prepared from protoscoleces, the banding patterns around Em18 were much simpler than those from microvesicles. Therefore, for serodiagnosis of E. multilocularis, antigens should be carefully prepared from protoscoleces rather than microvesicles from the rat.

Single-molecule analysis of chemotactic signaling in Dictyostelium cells

Single-molecule imaging techniques were used to reveal the binding of individual cyclic adenosine 3',5'-monophosphate molecules to heterotrimeric guanine nucleotide-binding protein coupled receptors on the surface of living Dictyostelium discoideum cells. The binding sites were uniformly distributed and diffused rapidly in the plane of the membrane. The probabilities of individual association and dissociation events were greater for receptors at the anterior end of the cell. Agonist-induced receptor phosphorylation had little effect on any of the monitored properties, whereas G protein coupling influenced the binding kinetics. These observations illustrate the dynamic properties of receptors involved in gradient sensing and suggest that these may be polarized in chemotactic cells.

Neurocysticercosis and echinococcosis in Asia: recent advances in the establishment of highly reliable differential serodiagnosis for international collaboration

Neurocysticercosis (NCC) and echinococcosis, caused by the larval stage of taeniid cestodes, are recognized as major parasitic zoonoses threatening human life worldwide. Cystic echinococcosis (CE), caused by Echinococcus granulosus, has well been known to be more widely distributing in Europe and Asia (Eurasia) than alveolar echinococcosis (AE) caused by E. multilocularis. However, it has recently been found that AE is more widely distributing or spreading in Eurasia. Furthermore, NCC caused by Taenia solium is also spreading in Eurasia. Due to the lack of reliable methodology for diagnosing these zoonotic cestodiases worldwide, prevalence rates of these diseases are extremely underestimated. Our group has been working for the establishment of differential serodiagnosis and molecular diagnosis of AE. CE and NCC as international collaboration projects sponsored by the Ministry of Education, Japan from 1994 until 2000 at least. In this paper, we introduce (1) the most recent original work on the establishment of differential serodiagnoses of NCC, AE and CE, (2) international collaboration work on epidemiology of these diseases in several countries, and discuss (3) what we can and should do for the control of such global parasitic diseases. It is stressed that international collaboration or cooperation work on the control of parasitic diseases is only successful based on the original scientific contribution of high standard.

Effects of bezafibrate on beta-cell function of rat pancreatic islets

Bezafibrate is an activator of peroxisome proliferator-activated receptors (PPAR) alpha. The present study was performed to investigate the effects of bezafibrate and the PPAR alpha activator, 4-Cholro-6-(2.3-xylidino)-2-pyrimidin-ylthio acetic acid (WY14643), on the beta-cell function of rat pancreatic islets in vitro. In islets cultured with 300 microM bezafibrate or WY14643 for 8 h, a low glucose concentration induced insulin release and increased the levels of mRNA for PPAR alpha, acyl CoA oxidase, carnitine palmitoyl transferase-1, pyruvate dehydrogenase E1 alpha or pyruvate carboxylase. In contrast, after a 48-h culture period, a high glucose concentration induced insulin release and islet insulin content, but decreased the levels of mRNA for glucose transporter-2 (GLUT-2), preproinsulin or pancreatic/duodenal homeobox-1. Diazoxide, the KATP channel opener, restored these responses. We conclude that bezafibrate enhances insulin release through the activation of PPAR alpha gene expression during a short culture period, whereas it may contribute to beta-cell dysfunction through the mechanism of "excessive stimulation" during longer culture periods.

The role of cyclic AMP in the pathogenesis of glucose desensitization in rat pancreatic islets

Adenosine-3',5'-cyclic monophosphate (cyclic AMP) promotes exocytosis of insulin in pancreatic beta cells. This study was performed to investigate the role of cyclic AMP in the pathogenesis of glucose desensitization in rat pancreatic islets. In islets cultured with high glucose for 48 hours, 27 mmol/L glucose-induced insulin release was markedly impaired, while 3.3 mmol/L glucose-or arginine-induced insulin release was enhanced, indicating glucose desensitization. Islet cyclic AMP content was 190% enhanced in high glucose-culture islets for 48 hours. In islets cultured with dibutyryl-cyclic AMP (dbcAMP) or 3-isobutyl methy-xanthine (IBMX), islet insulin content or 27 mmol/L glucose-induced insulin release was deteriorated. In contrast, 3.3 mmol/L glucose- or arginine-induced insulin release was increased, which was similar to glucose-desensitized islets. Wash-out of dbc AMP for the last 24 hours of the 48-hour culture period restored impaired high glucose-induced insulin release in the same manner as wash-out of high glucose. Diazoxide, the KATP channel opener, also restored impaired high glucose-induced insulin release from dbcAMP-cultured islets. The data suggest that enhancement of cyclic AMP in high glucose-culture islets may be one of the pathogenesis of glucose desensitization.

Effects of free fatty acids on beta-cell functions: a possible involvement of peroxisome proliferator-activated receptors alpha or pancreatic/duodenal homeobox

It is well known that acute administration of fatty acids enhances insulin release from beta cells, although chronic exposure to fatty acids inhibits insulin release (lipotoxicity). The mechanism for these reciprocal effects of fatty acids on insulin release remains to be elucidated. The present study was performed to investigate the effects of fatty acids on gene expression related to glucose metabolism or insulin biosynthesis. In islets cultured with palmitate for 8 hours, glucose-induced insulin release was enhanced together with increment of pyruvate carboxylase (PC) mRNA or peroxisome proliferator-activated receptors (PPAR)alpha. In contrast, by extending the culture period up to 48 hours, glucose-induced insulin release or islet insulin content was significantly impaired by the coexistence of palmitate. Concomitantly, PC, PPARalpha, GLUT-2, glucokinase (GK), preproinsulin, or pancreatic/duodenal homeobox-1 (PDX-1) mRNA were significantly suppressed in those islets cultured for 48 hours with palmitate. These data may imply that during short-term culture period palmitate promotes PPARalpha gene expression, which enhances PC mRNA expression leading to the enhancement of insulin release, whereas during long-term culture period, palmitate rather inhibits PPARalpha mRNA, which reduces PC mRNA expression. Furthermore, palmitate reduces GLUT-2, GK, or preproinsulin mRNA expression probably through the inhibition of PDX-1 mRNA.

Pyrobaculum oguniense sp. nov., a novel facultatively aerobic and hyperthermophilic archaeon growing at up to 97 degrees C

A novel hyperthermophilic, heterotrophic, rod-shaped archaeon was isolated from a terrestrial hot spring at Oguni-cho, Kumamoto Prefecture, Japan. The new isolate, strain TE7T, grew under aerobic, microaerobic and anaerobic conditions. Isolate TE7T grew optimally at 90-94 degrees C and pH 7.0-7.5 (adjusted at 25 degrees C) under atmospheric air with vigorous shaking. Strain TE7T cells were motile rods 2-10 microm in length and covered with a surface-layer lattice. Cell yields at 90 degrees C under aerobic conditions were twice that under anaerobic conditions. Under aerobic conditions, growth was inhibited by elemental sulfur, but thiosulfate stimulated growth. Under anaerobic conditions, no growth was observed in the presence of nitrate and nitrite, but elemental sulfur, thiosulfate, L-cystine and oxidized glutathione stimulated growth. The 16S rDNA sequence of TE7T exhibited a close relationship to the sequences of Pyrobaculum aerophilum and Thermoproteus neutrophilus, which belong to the cluster of the genus Pyrobaculum. DNA-DNA hybridization analysis showed a low level of DNA similarity between TE7T and previously described Pyrobaculum species. As TE7T is phenotypically and phylogenetically different from the other members of this genus, it is described as a new species named Pyrobaculum oguniense (type strain TE7T = JCM 10595T = DSM 13380T).