Natural transformation of the filamentous cyanobacterium Phormidium lacuna

Research for biotechnological applications of cyanobacteria focuses on synthetic pathways and bioreactor design, while little effort is devoted to introduce new, promising organisms in the field. Applications are most often based on recombinant work, and the establishment of transformation can be a risky, time-consuming procedure. In this work we demonstrate the natural transformation of the filamentous cyanobacterium Phormidium lacuna and insertion of a selection marker into the genome by homologous recombination. This is the first example for natural transformation filamentous non-heterocystous cyanobacterium. We found that Phormidium lacuna is polyploid, each cell has about 20–90 chromosomes. Transformed filaments were resistant against up to 14 mg/ml of kanamycin. Formerly, natural transformation in cyanobacteria has been considered a rare and exclusive feature of a few unicellular species. Our finding suggests that natural competence is more distributed among cyanobacteria than previously thought. This is supported by bioinformatic analyses which show that all protein factors for natural transformation are present in the majority of the analyzed cyanobacteria

Low-energy unphysical saddle in polynomial molecular potentials

Vibrational spectra of polyatomic molecules are often obtained from a polynomial expansion of the adiabatic potential around a minimum. For several molecules, we show that such an approximation displays an unphysical saddle point of comparatively small energy, leading to a region where the potential is negative and unbounded. This poses an upper limit for a reliable evaluation of vibrational levels. We argue that the presence of such saddle points is general.Comment: The preprint version of the published Mol. Phys. paper, 19 pages, 3 figure

Micro-ribonucleic acid-155 is a direct target of Meis1, but not a driver in acute myeloid leukemia

Micro-ribonucleic acid-155 (miR-155) is one of the first described oncogenic miRNAs. Although multiple direct targets of miR-155 have been identified, it is not clear how it contributes to the pathogenesis of acute myeloid leukemia. We found miR-155 to be a direct target of Meis1 in murine Hoxa9/Meis1 induced acute myeloid leukemia. The additional overexpression of miR-155 accelerated the formation of acute myeloid leukemia in Hoxa9 as well as in Hoxa9/Meis1 cells However, in the absence or following the removal of miR-155, leukemia onset and progression were unaffected. Although miR-155 accelerated growth and homing in addition to impairing differentiation, our data underscore the pathophysiological relevance of miR-155 as an accelerator rather than a driver of leukemogenesis. This further highlights the complexity of the oncogenic program of Meis1 to compensate for the loss of a potent oncogene such as miR-155. These findings are highly relevant to current and developing approaches for targeting miR-155 in acute myeloid leukemia

VIPER-2: a prospective, randomized single-center comparison of 2 different closure devices with a hemostatic wound dressing for closure of femoral artery access sites

PURPOSE: To report the outcome of a prospective randomized safety and performance trial of 2 access site closure devices versus a wound dressing. METHODS: Between October 2005 and July 2006, 852 consecutive patients (605 men; mean age 67 years) undergoing diagnostic or interventional catheterization procedures thru a 5- or 6-F femoral sheath were randomized to one of the 3 closure methods: a collagen plug device (Angio-Seal), a clip (StarClose), or a wound dressing (D-Stat Dry). The efficacy of the devices was assessed, as well as the complications occurring at the puncture site during the hospital stay. The primary endpoint of the study was the cumulative incidence of access site pseudoaneurysm, major access site bleeding requiring transfusion, access site vascular surgery, or death from all causes. RESULTS: There were no significant differences in baseline characteristics between the 3 treatment groups. The primary endpoint was reached in 20 (7.1%) of 281 patients treated with D-Stat Dry and in 11 (1.9%) of 571 patients treated with the mechanical closure devices (p>0.0001). There was no significant difference among the mechanical closure devices concerning the incidence of the primary endpoint (Angio-Seal 1.1% versus StarClose 2.8%; p = 0.13). CONCLUSION: The collagen plug device had the lowest rates of major and minor access site-related complications after removal of 5- or 6-F femoral sheaths. The difference between the mechanical closure devices concerning the incidence of the primary endpoint did not reach statistical significance. The wound dressing showed significantly higher major and minor complication rates