To investigate the presence of Cd-binding components other than MT, which is mainly cytosolic, 109Cd was analyzed in different tissue subfractions after tracer administration in vivo. Although cytosolic binding components are quantitatively most important and can account for the stage-related accumulation pattern, a second nuclear-associated component is detected in greater amounts in immature than in mature stages. In rodents, the amount of Cd associated with the nucleus increases with increasing extracellular Cd, and this has been interpreted as induction of metal-binding nuclear proteins and/or translocation of metal-binding cytosolic proteins. ventolin 100 mcg
Alternatively, nuclear-associated Cd may displace zinc in polymerases, other metalloenzymes, or transcription factors, all of which are present in greater amounts in nuclei of proliferating cells. It may be relevant here that androgen and estrogen receptors, which are zinc finger proteins, are concentrated in PrM regions of shark testis. Finally, because Cd has a high affinity for nucleic acids and accumulates within the nuclear compartment even when present in trace amounts, high levels of nuclear-associated Cd in the GZ/PrM region may reflect the higher percentage of cells with replicated DNA.