Single cell observation of ligand‐induced desensitization of B‐cell membrane immunoglobulin‐mediated calcium signals

Abstract

Using a digital imaging fluorescence microscope we have observed the membrane immunoglobulin (mIg)-induced desensitization of calcium signals in individual BAL17 B lymphoma cells which express two kinds of antigen rcccptors, m&M and mIgD. The mIgD-mediated desensitization was partly abrogated by pretrealing the cells with phorbol 12.myristate I f-acetate (PMA) for 24 h, however, the mIgM-mediated one was not affected by the pretreatment. This supports the idea that at least two mechanisms are operative for m&-induced desensitization in B cells.

Role of Calpain in Human Sperm Activated by Progesterone for Fertilization

“…We observed an increase of the [Ca 2+ ] i in individual human sperm by a digital imaging fluorescence microscope (Yamada et al, 1992;Shimizu et al, 1993). The sperm samples were incubated with HTF in an observation chamber (MatTek Corp., Ashland, MA, USA) coated with poly-L-lysine (Sigma, St. Louis, MO, USA) for 3 h at 37 °C under 5% CO 2 and air.…”