Characterization of the Single Stranded DNA Binding Protein SsbB Encoded in the Gonoccocal Genetic Island

Background: Most strains of Neisseria gonorrhoeae carry a Gonococcal Genetic Island which encodes a type IV secretion system involved in the secretion of ssDNA. We characterize the GGI-encoded ssDNA binding protein, SsbB. Close homologs of SsbB are located within a conserved genetic cluster found in genetic islands of different proteobacteria. This cluster encodes DNA-processing enzymes such as the ParA and ParB partitioning proteins, the TopB topoisomerase, and four conserved hypothetical proteins. The SsbB homologs found in these clusters form a family separated from other ssDNA binding proteins. Methodology/Principal Findings: In contrast to most other SSBs, SsbB did not complement the Escherichia coli ssb deletion mutant. Purified SsbB forms a stable tetramer. Electrophoretic mobility shift assays and fluorescence titration assays, as well as atomic force microscopy demonstrate that SsbB binds ssDNA specifically with high affinity. SsbB binds single-stranded DNA with minimal binding frames for one or two SsbB tetramers of 15 and 70 nucleotides. The binding mode was independent of increasing Mg 2+ or NaCl concentrations. No role of SsbB in ssDNA secretion or DNA uptake could be identified, but SsbB strongly stimulated Topoisomerase I activity

PET Imaging of Soluble Yttrium-86-Labeled Carbon Nanotubes in Mice

The potential medical applications of nanomaterials are shaping the landscape of the nanobiotechnology field and driving it forward. A key factor in determining the suitability of these nanomaterials must be how they interface with biological systems. Single walled carbon nanotubes (CNT) are being investigated as platforms for the delivery of biological, radiological, and chemical payloads to target tissues. CNT are mechanically robust graphene cylinders comprised of sp(2)-bonded carbon atoms and possessing highly regular structures with defined periodicity. CNT exhibit unique mechanochemical properties that can be exploited for the development of novel drug delivery platforms. In order to evaluate the potential usefulness of this CNT scaffold, we undertook an imaging study to determine the tissue biodistribution and pharmacokinetics of prototypical DOTA-functionalized CNT labeled with yttrium-86 and indium-111 ((86)Y-CNT and (111)In-CNT, respectively) in a mouse model.The (86)Y-CNT construct was synthesized from amine-functionalized, water-soluble CNT by covalently attaching multiple copies of DOTA chelates and then radiolabeling with the positron-emitting metal-ion, yttrium-86. A gamma-emitting (111)In-CNT construct was similarly prepared and purified. The constructs were characterized spectroscopically, microscopically, and chromatographically. The whole-body distribution and clearance of yttrium-86 was characterized at 3 and 24 hours post-injection using positron emission tomography (PET). The yttrium-86 cleared the blood within 3 hours and distributed predominantly to the kidneys, liver, spleen and bone. Although the activity that accumulated in the kidney cleared with time, the whole-body clearance was slow. Differential uptake in these target tissues was observed following intravenous or intraperitoneal injection.The whole-body PET images indicated that the major sites of accumulation of activity resulting from the administration of (86)Y-CNT were the kidney, liver, spleen, and to a much less extent the bone. Blood clearance was rapid and could be beneficial in the use of short-lived radionuclides in diagnostic applications

Towards eco-friendly crop protection: natural deep eutectic solvents and defensive secondary metabolites

Plant science

Psychopathy in adolescent offenders: an item response theory study of the antisocial process screening device-self report and the Psychopathy Checklist: Youth Version.

Few studies have examined the item functioning of youth psychopathy measures or compared the functioning of clinician and self-report based indices. Even fewer studies have made these comparisons in both male and female adolescent samples. The present study examined the applicability of items from two psychopathy measures, the Antisocial Process Screening Device (APSD; Frick, P. J., and Hare, R. D., 2001, The Antisocial Process Screening Device. Toronto, Ontario, Canada: Multi-Health Systems) and Psychopathy Checklist: Youth Version (PCL:YV; Forth, A. E., Kosson, D. S., and Hare, R. D., 2003, The Psychopathy Checklist: Youth Version. Toronto, Ontario, Canada: Multi-Health Systems), to adolescent boys and girls who had come into contact with the law. Item Response Theory was used to test item functioning of the two psychopathy indices. Examination of the Item Response Theory trace lines indicated that the APSD and the PCL:YV have both highly discriminating and poorly discriminating items and that the measures differ in the regions of psychopathy they cover. The PCL:YV is particularly effective at assessing interpersonal and affective features of psychopathy and to a lesser extent, lifestyle and antisocial features. The APSD appears to be effective at assessing narcissism and impulsivity but not callousness. In addition, the items most discriminating of the underlying construct of psychopathy for males and females demonstrate some important differences. These findings suggest that the measures may tap different underlying elements of the same overlaying construct. This may account for modest correlations between the measures. The findings suggest that clinicians should be aware of the regions that each measure best taps and also suggest that continued refinement and revisions to the youth psychopathy measures may be required