Calcium binding to metallochromic dyes and calmodulin in the presence of combined, AC-DC magnetic fields.

The possibility that weak, ac and dc magnetic fields in combination may affect binding equilibria of calcium-ions (Ca2+) was investigated with two metallochromic dyes as calcium-binding molecules: murexide and arsenazo III. Calcium-dye equilibria were followed by measuring solution absorbances with a fiber-optic spectrophotometer. A Ca(2+)-arsenazo solution was also used indirectly to monitor the binding of Ca2+ to calmodulin. Parallel, ac and dc magnetic fields were applied to each preparation. The ac magnetic field was held constant during each of a series of experiments at a frequency in the range between 50 and 120 Hz (sine wave) or at 50 pps (square wave) and at an rms flux density in the range between 65 and 156 microT. The dc magnetic field was then varied from 0 to 299 microT at 1.3 microT increments. The magnetic fields did not measurably affect equilibria in the binding of metallochromic dyes or calmodulin to Ca2+.     

An Automated Double Staining Procedure for Bone and Cartilage

Differential skeletal staining is an important part of developmental toxicologic studies. Traditionally these studies have required time-consuming differentiation of one or both stains used and careful attention to the maceration step to prevent specimen destruction. We present a fully automated protocol which does not require differentiation of either dye and incorporates a controlled maceration step which is highly reproducible. This has resulted in high quality staining that is reproducible, stable, and can be done in volume with minimal personnel time. The process involves the staining of skinned, eviscerated specimens fixed in 95% ethanol. Using an automated tissue processor, the specimen is stained in alcian blue for 24 hr, macerated in 3% potassium hydroxide for 24 hr and stained with murexide for 24 hr. The specimens are cleared and preserved in glycerol. Within three days specimens have red stained bone and blue stained cartilage. The procedure was developed using 20-day-old Sprague-Dawley rat fetuses to evaluate the feasibility of using the procedure for teratology studies involving the fetal skeleton. Evenly stained specimens can be examined within three days and stored for years without loss of staining.     

Phytochrome modulation of calcium fluxes in wheat (Triticum aestivum L.) protoplasts

Employing the metallochromic dye murexide and by monitoring the uptake of radiolabelled calcium, photoreversible calcium fluxes were measured in wheat leaf protoplast suspensions. Results obtained by both methods were identical — red light promoted and subsequent far-red irradiation reversed an influx of Ca⁺⁺ ions into the protoplasts. These findings imply phytochrome regulation of Ca⁺⁺ fluxes across the plasma membrane. The influx of Ca⁺⁺ stimulated by 2 min red irradiation could be maintained in total darkness for the initial 16–18 min after illumination, after which a 6–8 min efflux process was triggered and the basal Ca⁺⁺ level restored. Verapamil, a calcium channel blocker, inhibited the red-promoted influx, whereas the far-red mediated efflux could be checked by the use of the ATPase inhibitor vanadate, and also by the calmodulin antagonist chlorpromazine, thus suggesting a role of ion channels and pumps in phytochrome-controlled Ca⁺⁺ fluxes. The possible involvement of phosphoinositides in phytochrome-modulated calcium fluxes was also investigated.Abbreviations A difference in absorbance - CPZ chlorpromazine - FR far-red (light) - MX murexide - PI phosphatidylinositol - PIP₂ phosphatidylinositol 4, 5-bisphosphate - PIPES piperazine-N,N-bis[2-ethanesulfonic acid] - POPOP 1, 4-bis [2-(5-phenyl-1, 3-oxazolyl)]-benzene - PPO 2, 5-diphenyl-1, 3-oxazole - R red (light) - SOV sodium orthovanadate     

Adult rodent double skeletal stain

Rodent embryo double skeletal staining has long played a role in toxicological studies and is now an important part of selected genetic studies involving knockout or transgenic animals. However, phenotypic changes are sometimes not seen until animals reach adulthood. This study expands a previously developed embryonic staining method for use with adult mice.     

Adult rodent double skeletal stain

Rodent embryo double skeletal staining has long played a role in toxicological studies and is now an important part of selected genetic studies involving knockout or transgenic animals. However, phenotypic changes are sometimes not seen until animals reach adulthood. This study expands a previously developed embryonic staining method for use with adult mice.