Quinaldine

Abstract: Quinaldine-based croconaine dyes synthesized by the condensation reaction between croconic acid and the respective quinaldinium salts are described. These dyes exhibit absorption maximum in the infrared region (840−870 nm) with high molar extinction coefficients (1−5 × 105 M-1 cm-1) and have very low fluorescence quantum yields. Upon binding to divalent metal ions, these dyes were found to form complexes with a 2:1 stoichiometry having high association constants of the order of 1011−1014 M-2, while the monovalent metal ions showed negligible affinity. The binding of the croconaine dye 3d with divalent metal ions especially Zn2+, Pb2+, and Cd2+ led to significant chelation-enhanced fluorescence emission. The broadening of the aromatic signals, vinylic and N-methyl protons and the negligible changes at the aliphatic region of the dye 3d in the 1H NMR spectrum in the presence of Zn2+, indicate that the binding occurs at the carbonyl groups of the croconyl ring. The shift in the croconyl carbonyl stretching f...

Abstract: Bacteria of the genus Arthrobacter are ubiquitous in soil environments and can be considered as true survivalists. Arthrobacter sp. strain Rue61a is an isolate from sewage sludge able to utilize quinaldine (2-methylquinoline) as sole carbon and energy source. The genome provides insight into the molecular basis of the versatility and robustness of this environmental Arthrobacter strain. The genome of Arthrobacter sp. Rue61a consists of a single circular chromosome of 4,736,495 bp with an average G + C content of 62.32%, the circular 231,551-bp plasmid pARUE232, and the linear 112,992-bp plasmid pARUE113 that was already published. Plasmid pARUE232 is proposed to contribute to the resistance of Arthrobacter sp. Rue61a to arsenate and Pb2+, whereas the linear plasmid confers the ability to convert quinaldine to anthranilate. Remarkably, degradation of anthranilate exclusively proceeds via a CoA-thioester pathway. Apart from quinaldine utilization, strain Rue61a has a limited set of aromatic degradation pathways, enabling the utilization of 4-hydroxy-substituted aromatic carboxylic acids, which are characteristic products of lignin depolymerization, via ortho cleavage of protocatechuate. However, 4-hydroxyphenylacetate degradation likely proceeds via meta cleavage of homoprotocatechuate. The genome of strain Rue61a contains numerous genes associated with osmoprotection, and a high number of genes coding for transporters. It encodes a broad spectrum of enzymes for the uptake and utilization of various sugars and organic nitrogen compounds. A. aurescens TC-1 is the closest sequenced relative of strain Rue61a. The genome of Arthrobacter sp. Rue61a reflects the saprophytic lifestyle and nutritional versatility of the organism and a strong adaptive potential to environmental stress. The circular plasmid pARUE232 and the linear plasmid pARUE113 contribute to heavy metal resistance and to the ability to degrade quinaldine, respectively.

Abstract: Plasma chloride and corticosteroid concentrations were measured in yearling striped bass (Morone saxatilis) exposed to 25 mg/L tricaine methanesulfonate, 2.5 mg/L quinaldine, or 0.1 mg/L etomidate (an experimental drug), alone and in combination with 10 g/L salt (NaCl). Plasma chloride levels were unaffected in all treatments during a 15-min exposure and during a 10-min period of close confinement in a dipnet. Plasma corticosteroids increased in fish exposed to salt alone and in fish exposed to tricaine methanesulfonate or quinaldine, either alone or in combination with salt. Etomidate alone or combined with salt limited the increase in plasma corticosteroids during exposure and confinement. Etomidate appears to be a useful drug for suppressing physiological changes during the handling and transportation of striped bass.