Methylobacterium Genome Sequences: A Reference Blueprint to Investigate Microbial Metabolism of C1 Compounds from Natural and Industrial Sources

Methylotrophy describes the ability of organisms to grow on reduced organic compounds without carbon-carbon bonds. The genomes of two pink-pigmented facultative methylotrophic bacteria of the Alpha-proteobacterial genus Methylobacterium, the reference species Methylobacterium extorquens strain AM1 and the dichloromethane-degrading strain DM4, were compared. Methodology/Principal Findings The 6.88 Mb genome of strain AM1 comprises a 5.51 Mb chromosome, a 1.26 Mb megaplasmid and three plasmids, while the 6.12 Mb genome of strain DM4 features a 5.94 Mb chromosome and two plasmids. The chromosomes are highly syntenic and share a large majority of genes, while plasmids are mostly strain-specific, with the exception of a 130 kb region of the strain AM1 megaplasmid which is syntenic to a chromosomal region of strain DM4. Both genomes contain large sets of insertion elements, many of them strain-specific, suggesting an important potential for genomic plasticity. Most of the genomic determinants associated with methylotrophy are nearly identical, with two exceptions that illustrate the metabolic and genomic versatility of Methylobacterium. A 126 kb dichloromethane utilization (dcm) gene cluster is essential for the ability of strain DM4 to use DCM as the sole carbon and energy source for growth and is unique to strain DM4. The methylamine utilization (mau) gene cluster is only found in strain AM1, indicating that strain DM4 employs an alternative system for growth with methylamine. The dcm and mau clusters represent two of the chromosomal genomic islands (AM1: 28; DM4: 17) that were defined. The mau cluster is flanked by mobile elements, but the dcm cluster disrupts a gene annotated as chelatase and for which we propose the name “island integration determinant” (iid).Conclusion/Significance These two genome sequences provide a platform for intra- and interspecies genomic comparisons in the genus Methylobacterium, and for investigations of the adaptive mechanisms which allow bacterial lineages to acquire methylotrophic lifestyles.Organismic and Evolutionary Biolog

Rare suprasellar glioblastoma: report of two cases and review of the literature

BACKGROUND AND IMPORTANCE: The suprasellar and hypothalamic/chiasmatic regions can harbor a broad range of pathologic conditions, both neoplastic and nonneoplastic; however, malignant gliomas are extremely rare in those regions. CLINICAL PRESENTATIONS: Patient 1 was a 70 year-old man with weight loss and rapidly progressive visual impairment. A mass centered in the hypothalamus was detected on magnetic resonance (MR) imaging. The second patient, a 45 year-old woman, complained of visual symptoms and headaches. MR imaging revealed a combined intra- and suprasellar mass. In both instances, the preoperative differential diagnosis favored craniopharyngioma. Histological examination confirmed the diagnosis of glioblastoma. CONCLUSION: We report two rare adult cases of hypothalamic/chiasmatic glioblastoma. The authors review the literature, highlighting the importance of considering this rare entity in the differential diagnosis of suprasellar and hypothalamic lesions

Practical data acquisition method for human brain tumor amide proton transfer (APT) imaging

Amide proton transfer (APT) imaging is a type of chemical exchange-dependent saturation transfer (CEST) magnetic resonance imaging (MRI) in which amide protons of endogenous mobile proteins and peptides in tissue are detected. Initial studies have shown promising results for distinguishing tumor from surrounding brain in patients, but these data were hampered by magnetic field inhomogeneity and a low signal-to-noise ratio (SNR). Here a practical six-offset APT data acquisition scheme is presented that, together with a separately acquired CEST spectrum, can provide B0-inhomogeneity corrected human brain APT images of sufficient SNR within a clinically relevant time frame. Data from nine brain tumor patients at 3T shows that APT intensities were significantly higher in the tumor core, as assigned by gadolinium-enhancement, than in contralateral normal-appearing white matter (CNAWM) in patients with high-grade tumors. Conversely, APT intensities in tumor were indistinguishable from CNAWM in patients with low-grade tumors. In high-grade tumors, regions of increased APT extended outside of the core into peripheral zones, indicating the potential of this technique for more accurate delineation of the heterogeneous areas of brain cancers. © 2008 Wiley-Liss, Inc.link_to_OA_fulltex