Amino acid residues critical for DNA binding and inducer recognition in CbnR, a LysR-type transcriptional regulator from Cupriavidus necator NH9.

CbnR, a LysR-type transcriptional regulator from Cupriavidus necator NH9, activates the transcription of chlorocatechol-degradative enzymes. To activate the transcription, CbnR needs to bind not only to the cbnA promoter but also to the inducer. In this study, the transcriptional activity and DNA-binding activity of twenty-five mutants of CbnR were analyzed. Of the 17 mutants of the DNA-binding domain, 11 mutants lost their ability to activate transcription. While most mutants without transcriptional activation did not show DNA-binding activity, Asn17Ala, Gln29Ala, and Pro30Ala retained DNA-binding activity, suggesting that transcriptional activation by CbnR requires more than its binding to promoter DNA. Of the 8 mutants of the regulatory domain, 6 mutants changed their responses to the inducer, when compared with wild-type CbnR. Interestingly, Arg199Ala and Val246Ala induced constitutive expression of the cbnA promoter without the inducer, suggesting that these mutations brought about a conformational change mimicking that induced by the inducer molecule.

The strain of unfamiliar conspecifics affects stress identification in rats.

Humans show distinct social behaviours when we evaluate an individual as being a member of the same group and recognize social similarity to the individual. One example is more accurate identification of emotion in that individual. Our previous studies proposed that rats recognize social similarity to certain strains of unfamiliar rats. It is therefore possible that the strain of unfamiliar conspecifics affects stress identification in rats. Wistar subject rats were allowed to explore a pair of unfamiliar Wistar, Sprague-Dawley (SD), Long-Evans (LE), or Fischer344 (F344) stimulus rats. To induce differences in stress, one of the stimulus rats had received foot shocks immediately before the test. It was found that the subjects showed biased interaction towards the shocked Wistar and SD stimulus rats, but not toward the shocked LE or F344 stimulus rats. Subsequent experiments confirmed that the biased interaction towards the shocked Wistar and SD stimulus rats was driven by stress in these stimulus rats. In addition, the lack of biased interaction towards the shocked LE and F344 stimulus rats did not appear to be due to procedural reasons. The experiment using LE subject rats further confirmed that the shocked LE stimulus rats emitted distress signals. These results suggested that Wistar rats could identify stress in unfamiliar Wistar and SD rats, but not in unfamiliar LE or F344 rats. Therefore, rats appear to recognize social similarity to certain unfamiliar strains of rats.

Hypercapnic respiratory distress and loss of consciousness: a complication of supraclavicular brachial plexus block.

Supraclavicular brachial plexus block is a common anesthetic technique performed for surgery of the upper extremities. We experienced a case of acute hypercapnic respiratory distress with loss of consciousness during creation of an arteriovenous fistula under ultrasound-guided supraclavicular brachial plexus block using 30 mL of 0.75 % ropivacaine. We detected ipsilateral hemidiaphragmatic paralysis by means of M-mode ultrasonography of the block. We thus speculate that phrenic nerve palsy caused by supraclavicular brachial plexus block was the underlying mechanism of the event. Bedside ultrasonography played a pivotal role in making a differential diagnosis and in managing this patient.

DNA cleavage by pentadentate iron(II) complexes containing fluoro-substituted phenyl groups.

Four pentadentate iron(II) complexes containing non- or fluoro-substituted phenyl group (2b-2e) were synthesized and cleaving activity of them to pUC19 DNA was evaluated in the presence of hydrogen peroxide. DNA cleavage activity increased with the number of substituted fluorine atoms on the phenyl group of 2b.