A practical guide to the preparation of Ca(2+) buffers.

Calcium (Ca(2+)) is a critical regulator of an immense array of biological processes, and the intracellular [Ca(2+)] that regulates these processes is ~ 10,000 lower than the extracellular [Ca(2+)]. To study and understand these myriad Ca(2+)-dependent functions requires control and measurement of [Ca(2+)] in the nano- to micromolar range (where contaminating Ca(2+) is a significant problem). As with pH, it is often essential to use Ca(2+) buffers to control free [Ca(2+)] at the desired biologically relevant concentrations.

Phosphoinositide metabolism at fertilization of sea urchin eggs measured with a GFP-probe.

Fertilization elicits a dramatic, transient rise in Ca2+ within the egg which is an essential component of egg activation and consequent initiation of development. In the sea urchin egg, three distinct Ca2+ stores have been identified which could, either individually or in combination, initiate Ca2+ release at fertilization. Inositol 1,4,5-trisphosphate (IP3) production by phospholipase C (PLC) has been suggested as the singular signal in initiating the Ca2+ transient.

Some precautions in using chelators to buffer metals in biological solutions.

Chelators and associated computer programs are commonly used to buffer metal ions in biological experiments. This communication discusses common misunderstandings and pitfalls in use of these buffers and provides information on choosing the best metal buffer for different experimental situations.

Cortical Granules of Sea Urchin Eggs do not Undergo Exocytosis at the Site of Sperm-egg Fusion*: (cortical granules/fertilization/sea urchin/polarity/exocytosis).

Microscopic observations of sea urchin egg fertilization (phase contrast, Nomarski and transmission electron microscope) reveal that the cortical granules in the area of sperm egg-fusion do not undergo exocytosis. These intact granules remain associated with the sperm, moving into the egg cytoplasm with the entering sperm. This sperm-cortical granule association occurs before the sperm centriole affects microtubule organization and the sperm-cortical granule association is not affected by cytochalasin D or griseofulvin.