Magnetic resonance beacon to detect intracellular microRNA during neurogenesis.

Magnetic resonance imaging (MRI) offers great spatial resolution for viewing deep tissues and anatomy. We developed a self-assembling signal-on magnetic fluorescence nanoparticle to visualize intracellular microRNAs (miRNAs or miRs) during neurogenesis using MRI. The self-assembling nanoparticle (miR124a MR beacon) was aggregated by the incubation of three different oligonucleotides: a 3' adaptor, a 5' adaptor, and a linker containing miR124a-binding sequences. The T2-weighted magnetic resonance (MR) signal of the self-assembled nanoparticle was quenched when miR124a was absent from test tubes or was minimally expressed in cells and tissues. When miR124a was present in test tubes or highly expressed in vitro and in vivo during P19 cell neurogenesis, it hybridized with the miR124a MR beacon, causing the linker to detach, resulting in increased signal-on MRI intensity. This MR beacon can be used as a new imaging probe to monitor the miRNA-mediated regulation of cellular processes.

Marinobacterium rhizophilum sp. nov., isolated from the rhizosphere of the coastal tidal-flat plant Suaeda japonica.

A Gram-negative, strictly aerobic, marine bacterium, designated strain CL-YJ9(T), was isolated from sediment closely associated with the roots of a plant (Suaeda japonica) inhabiting a coastal tidal flat. Cells of the novel strain were straight and rod-shaped and were motile by means of monopolar flagella. A phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CL-YJ9(T) belongs to the genus Marinobacterium and was most closely related to Marinobacterium halophilum mano11(T) (94.1% sequence similarity) and to other members of the genus Marinobacterium (92.5-93.7% sequence similarity). The strain grew with 1-5% NaCl (optimum, 3%) and at 5-30 degrees C (optimum, approx. 25 degrees C) and pH 6.0-9.0 (optimum, pH 7.0). The predominant cellular fatty acids were summed feature 3 (C(16:1)omega7c and/or iso-C(15:0) 2-OH, 40.3%), C(18:1)omega7c (26.6%), C(16:0) (16.6%) and C(10:0) 3-OH (7.1%). The major isoprenoid quinone was Q-8. The G+C content of the genomic DNA was 61 mol%. On the basis of the data from this polyphasic study, strain CL-YJ9(T) belongs to the genus Marinobacterium but is distinguishable from the recognized species. Strain CL-YJ9(T) therefore represents a novel species, for which the name Marinobacterium rhizophilum sp. nov. is proposed. The type strain is CL-YJ9(T) (=KCCM 42386(T) =DSM 18822(T)).