Changes in hemolymph total CO content during the water-to-air respiratory transition of amphibiotic dragonflies.

Dragonflies (Odonata, Anisoptera) are amphibiotic; the nymph is aquatic and breathes water using a rectal gill before metamorphosing into the winged adult, which breathes air through spiracles. While the evolutionary and developmental transition from water breathing to air breathing is known to be associated with a dramatic rise in internal CO levels, the changes in blood-gas composition experienced by amphibiotic insects, which represent an ancestral air-to-water transition, are unknown. This study measured total CO (TCO) in hemolymph collected from aquatic nymphs and air-breathing adults of , (Aeshnidae), and (Libellulidae).

Simultaneous determination of doxycycline and chlortetracycline in real samples by europium-sensitized luminescence.

A simple luminescent methodology for the simultaneous determination of doxycycline and chlortetracycline in pharmaceutical preparations and human urine is proposed. Since the native fluorescence of both analytes is negligible, this method takes advantage of the lanthanide-sensitized luminescence, which provides increased sensitivity. Due to the strong overlapping between the luminescence spectra of both europium complexes, the use of luminescence decay curves to resolve mixtures of the analytes is proposed, particularly as these curves are more selective.