Transcriptional Regulation of Methanol Dehydrogenases in the Methanotrophic Bacterium Methylococcus capsulatus Bath by Soluble and Insoluble Lanthanides.

The effects of soluble and insoluble lanthanides on gene expression in Methylococcus capsulatus Bath were investigated. Genes for lanthanide-containing methanol dehydrogenases (XoxF-MDHs) and their calcium-containing counterparts (MxaFI-MDHs) were up- and down-regulated, respectively, by supplementation with soluble lanthanide chlorides, indicating that M. capsulatus has the "lanthanide switch" observed in other methanotrophs. Insoluble lanthanide oxides also induced the lanthanide switch and were dissolved by the spent medium of M. capsulatus, suggesting the presence of lanthanide-chelating compounds. A transcriptome ana-lysis indicated that a gene cluster for the synthesis of an enterobactin-like metal chelator contributed to the dissolution of insoluble lanthanides.

Isolation and Genomic Characterization of a Proteobacterial Methanotroph Requiring Lanthanides.

Although the bioavailability of rare earth elements (REEs, including scandium, yttrium, and 15 lanthanides) has not yet been examined in detail, methane-oxidizing bacteria (methanotrophs) were recently shown to harbor specific types of methanol dehydrogenases (XoxF-MDHs) that contain lanthanides in their active site, whereas their well-characterized counterparts (MxaF-MDHs) were Ca2+-dependent. However, lanthanide dependency in methanotrophs has not been demonstrated, except in acidic environments in which the solubility of lanthanides is high. We herein report the isolation of a lanthanide-dependent methanotroph from a circumneutral environment in which lanthanides only slightly dissolved. Methanotrophs were enriched and isolated from pond sediment using mineral medium supplemented with CaCl2 or REE chlorides. A methanotroph isolated from the cerium (Ce) chloride-supplemented culture, Methylosinus sp. strain Ce-a6, was clearly dependent on lanthanide. Strain Ce-a6 only required approximately 30 nM lanthanide chloride for its optimal growth and exhibited the ability to utilize insoluble lanthanide oxides, which may enable survival in circumneutral environments. Genome and gene expression analyses revealed that strain Ce-a6 lost the ability to produce functional MxaF-MDH, and this may have been due to a large-scale deletion around the mxa gene cluster. The present results provide evidence for lanthanide dependency as a novel survival strategy by methanotrophs in circumneutral environments.

Conductive Iron Oxides Promote Methanogenic Acetate Degradation by Microbial Communities in a High-Temperature Petroleum Reservoir.

Supplementation with conductive magnetite particles promoted methanogenic acetate degradation by microbial communities enriched from the production water of a high-temperature petroleum reservoir. A microbial community analysis revealed that Petrothermobacter spp. (phylum Deferribacteres), known as thermophilic Fe(III) reducers, predominated in the magnetite-supplemented enrichment, whereas other types of Fe(III) reducers, such as Thermincola spp. and Thermotoga spp., were dominant under ferrihydrite-reducing conditions. These results suggest that magnetite induced interspecies electron transfer via electric currents through conductive particles between Petrothermobacter spp. and methanogens. This is the first evidence for possible electric syntrophy in high-temperature subsurface environments.

Restoration of the growth of Escherichia coli under K+-deficient conditions by Cs+ incorporation via the K+ transporter Kup.

Biological incorporation of cesium ions (Cs+) has recently attracted significant attention in terms of the possible applications for bioremediation of radiocesium and their significant roles in biogeochemical cycling. Although high concentrations of Cs+ exhibit cytotoxicity on microorganisms, there are a few reports on the promotive effects of Cs+ on microbial growth under K+-deficient conditions. However, whether this growth-promoting effect is a common phenomenon remains uncertain, and direct correlation between growth promotion and Cs+ uptake abilities has not been confirmed yet. Here, we validated the growth promotive effects of Cs+ uptake under K+-deficient conditions using an Escherichia coli strain with an inducible expression of the Kup K+ transporter that has nonspecific Cs+ transport activities (strain kup-IE). The strain kup-IE exhibited superior growth under the Cs+-supplemented and K+-deficient conditions compared to the wild type and the kup null strains. The intracellular Cs+ levels were significantly higher in strain kup-IE than in the other strains, and were well correlated with their growth yields. Furthermore, induction levels of the kup gene, intracellular Cs+ concentrations, and the growth stimulation by Cs+ also correlated positively. These results clearly demonstrated that Cs+ incorporation via Kup transporter restores growth defects of E. coli under K+-deficient conditions.

Enrichment and isolation of Flavobacterium strains with tolerance to high concentrations of cesium ion.

Interest in the interaction of microorganisms with cesium ions (Cs(+)) has arisen, especially in terms of their potent ability for radiocesium bioaccumulation and their important roles in biogeochemical cycling. Although high concentrations of Cs(+) display toxic effects on microorganisms, there have been only limited reports for Cs(+)-tolerant microorganisms. Here we report enrichment and isolation of Cs(+)-tolerant microorganisms from soil microbiota. Microbial community analysis revealed that bacteria within the phylum Bacteroidetes, especially Flavobacterium spp., dominated in enrichment cultures in the medium supplemented with 50 or 200 mM Cs(+), while Gammaproteobacteria was dominant in the control enrichment cultures (in the presence of 50 and 200 mM K(+) instead of Cs(+)). The dominant Flavobacterium sp. was successfully isolated from the enrichment culture and was closely related to Flavobacterium chungbukense with 99.5% identity. Growth experiments clearly demonstrated that the isolate has significantly higher tolerance to Cs(+) compared to its close relatives, suggesting the Cs(+)-tolerance is a specific trait of this strain, but not a universal trait in the genus Flavobacterium. Measurement of intracellular K(+) and Cs(+) concentrations of the Cs(+)-tolerant isolate and its close relatives suggested that the ability to maintain low intracellular Cs(+) concentration confers the tolerance against high concentrations of external Cs(+).

Solitary amyloidosis of the sigmoid colon featuring submucosal tumor caused hematochezia.

A previously a healthy 64-year-old woman complained of a two-week history of hemorrhaging upon defecation. The laboratory and urinalysis findings were normal, and no serum or urine M components were detectable on protein electrophoresis. An air contrast barium enema revealed an elevated lesion measuring -20 mm in diameter with a smooth surface and a depression in the sigmoid colon. Colonoscopy revealed a red colored and congested tumor. The exposed surface of the submucosal tumor (SMT) center was somewhat yellow in color and covered with fuzz. All other portions of the colon were normal. The endoscopy and double-contrast barium revealed a normal upper gastrointestinal tract and a normal small intestine, respectively. A histopathological evaluation of a biopsy specimen obtained from the SMT suggested amyloid deposition. However, the other biopsy specimens of the esophagus, stomach, duodenal bulb, second portion of the duodenum, terminal ileum and other portions of the colon demonstrated no amyloid deposition. Colonoscopic ultrasonography (US) revealed the hypoechoic, homogeneous SMT to be mainly localized within the submucosa. An endoscopic submucosal resection (EMR) of the solitary amyloidosis was performed and the immunohistopathology revealed the entire SMT to consist of amyloid light chain kappa amyloid deposition. We considered that the US followed by EMR contributed to the precise diagnosis of solitary amyloidosis and the treatment of hematochezia caused by a solitary area of amyloidosis within the sigmoid colon.

Serum intact parathyroid hormone level after total thyroidectomy or total thyroidectomy plus lymph node dissection for thyroid nodules: report from 296 surgical cases.

BACKGROUND: Transient hypocalcemia is one of the postoperative complications of thyroidectomy for thyroid nodules, and intraoperative and postoperative intact parathyroid hormone (iPTH) assays are used to predict postoperative hypocalcemia. OBJECTIVES: The current study was conducted to evaluate a single serum iPTH measurement on postoperative day 1 (POD 1) as a means to predict hypocalcemia occurrence after total thyroidectomy (TT). PATIENTS AND METHODS: The subjects consisted of 36 patients who underwent TT and 260 patients who underwent TT plus lymph node (LN) dissection for thyroid nodules treatment. The TT performance procedure to prevent postoperative hypoparathyroidism combines parathyroid gland preservation in situ with autotransplantation of resected or devascularized parathyroid glands. The patients' serum iPTH level was measured on POD 1, and their serum calcium level was measured on POD 1 and on POD 3 while they were still inpatients. The serum iPTH level was subequently measured at each outpatient clinic visit until it recovered to the normal range. RESULTS: Hypoparathyroidism after TT and TT plus LN dissection was ultimately diagnosed in a total of 229 patients, and in 69 of them hypocalcemia was diagnosed on POD 1. All of the 69 patients diagnosed with hypocalcemia received calcium and vitamin D supplementation therapy. The serum iPTH level of 67 of 229 patients was within normal range on POD 1, and four of them developed hypocalcemia on POD 1. Permanent hypoparathyroidism developed in 37 of 296 patients after undergoing TT or TT plus LN dissection for thyroid nodules in the hospital. CONCLUSIONS: A single serum iPTH measurement on POD 1 is useful to determine whether or not to start calcium and vitamin D supplementation in order to maintain normocalcemia after surgery.

Torsades de Pointes induced by a combination of garenoxacin and disopyramide and other cytochrome P450, family 3, subfamily A polypeptide-4-influencing drugs during hypokalemia due to licorice.

We report an 82-year-old man who developed ventricular tachycardia and Torsades de Pointes (TdP) after oral administration of garenoxacin, a novel quinolone antibiotic agent that differs from the third-generation quinolones, for pneumonia. He had hypokalemia (K 2.3 mmol/L) induced by licorice and also had received disopyramide for arrhythmia, bicalutamide for prostate cancer, and silodosin for prostate hypertrophy. After taking him off all drugs and administering spironolactone supplemented with potassium, his low serum potassium level was ameliorated. Therefore, although garenoxacin reportedly causes fewer adverse reactions for cardiac rhythms than third-generation quinolone antibiotics, one must be cautious of the interference of other drugs during hypokalemia in order to prevent TdP.