Magnetic Alignment in Carps: Evidence from the Czech Christmas Fish Market

While magnetoreception in birds has been studied intensively, the literature on magnetoreception in bony fish, and particularly in non-migratory fish, is quite scarce. We examined alignment of common carps (Cyprinus carpio) at traditional Christmas sale in the Czech Republic. The sample comprised measurements of the directional bearings in 14,537 individual fish, distributed among 80 large circular plastic tubs, at 25 localities in the Czech Republic, during 817 sampling sessions, on seven subsequent days in December 2011. We found that carps displayed a statistically highly significant spontaneous preference to align their bodies along the North-South axis. In the absence of any other common orientation cues which could explain this directional preference, we attribute the alignment of the fish to the geomagnetic field lines. It is apparent that the display of magnetic alignment is a simple experimental paradigm of great heuristic potential.     

Detection of a calmodulin-sensitive cyclic nucleotide phosphodiesterase in rat parotid gland

Calmodulin coupled to Sepharose has provided a rapid and sensitive means of isolating a cyclic nucleotide phosphodiesterase activity which is stimulated by the calmodulin-Ca²⁺ complex, from rat parotid gland. Initial experiments established that phosphodiesterase activity sensitive to calmodulin and Ca²⁺ could not be demonstrated in crude extracts of rat parotid gland or after partial purification of rat parotid phosphodiesterase over DEAE-cellulose. However, it was possible to readily demonstrate the presence of a cyclic nucleotide phosphodiesterase activity regulated by calmodulin if the extracts were first purified by batch ion-exchange chromatography over DEAE-cellulose followed by affinity chromatography with calmodulin coupled to Sepharose. The batch ion-exchange chromatography step removed the major portion of free parotid calmodulin which could compete with calmodulin-coupled Sepharose for the proteins regulated by calmodulin. Thus, by employing an initial chromatography step over DEAE-cellulose to separate phosphodiesterase activity from calmodulin, it was possible to increase the recovery of calmodulin-sensitive phosphodiesterase after affinity chromatography with calmodulin coupled to Sepharose. This approach should be useful for demonstrating the presence of and for purifying other parotid proteins regulated by calmodulin.     

Evaluation of loss of active heparin in the peritoneal cavity during intermittent peritoneal dialysis]

Our studies aimed at determining a loss of active heparin from the peritoneal cavity after its intraperitoneal administration (250 JU/l of dialysis fluid) in 16 patients treated because of the end-stage renal failure with intermittent peritoneal dialysis and at comparing heparin influx clearance with that of glucose. It has been shown that heparin used in this dose loses 60-70% of its activity after 20-minute equilibration of dialysis fluid in the peritoneal cavity. Heparin influx clearance is higher than that of glucose but it depends on utilization of heparin in peritoneal cavity rather than on its penetration to the blood circulation.     

Resolution of the conformational distribution and dynamics of a flexible molecule using frequency-domain fluorometry

We report the first resolution of both the conformational distribution and end-to-end diffusion coefficient of a flexible molecule. This molecular information was recovered using only the donor intensity decay in a single solvent at a single viscosity, as observed by the technique of frequency-domain fluorometry. This technique can be extended to measurements of structural fluctuations of biological macromolecules.