Urea, in concentrations unique to the renal medulla, increases transcription and protein expression of several immediate–early genes (IEGs) including the zinc finger-containing transcription factor, Egr-1 . In the present study, the proximal 1.2 kb of the murine Egr-1 5 9 -flanking sequence conferred urea-responsiveness to a heterologous luciferase reporter gene when transiently transfected int...

Gulf toadfish (Opsanus beta) use a unique pulsatile urea excretion mechanism that allows urea to be voided in large pulses via the periodic insertion or activation of a branchial urea transporter. The precise cellular and subcellular location of the facilitated diffusion mechanism(s) remains unclear. An in vitro basolateral membrane vesicle (BLMV) preparation was used to test the hypothesis tha...

Because urea is bioenergetically expensive to synthesize, few aquatic teleostean (bony) fish make or excrete much urea beyond early development and excrete the majority of nitrogenous waste as the readily diffusible ammonia. The gulf toadfish is one of a few adult teleostean fish that excretes predominantly urea. Most studies of chemosensing by fish predators have focused on amino acids as odor...

In the title compound, C(13)H(10)FN(3)O(3), the dihedral angle between the fluoro-phenyl and nitro-phenyl ring planes is 6.51 (9)°. The crystal structure features N-H⋯O hydrogen bonds.