SPONTANEOUS RECOVERY OF FLUORESCENCE BY PHOTOBLEACHED SURFACE-ADSORBED PROTEINS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73314/1/j.1751-1097.1995.tb05264.x.pd

HYPOCHROMY IN MOLECULAR CRYSTALS

$^{1}$ M. Tahaka, Bull. Chem. Soc. Jap. 49, 3382 (1976).Author Institution:Transmittance measurements of the extinction coefficient along three crystallographic directions for thin carbozole crystals were made. The spectra obtained exhibit a strong decrease in intensity (hypochromy) for the ^{\prime}$B_{2}$ transition at 300 nm, whereas results derived from reflectance $spectra^{1}$ do not show strong effects in the extinction coefficient for this transition. Possible reasons for this discrepancy are discussed

Barriers to diffusion of plasma membrane proteins form early during guinea pig spermiogenesis.

The plasma membrane of the mature guinea pig sperm is segregated into at least four domains of different composition. Previous studies have shown that some proteins localized within these domains are free to diffuse laterally, suggesting that barriers to protein diffusion are responsible for maintaining the nonuniform distribution of at least some surface proteins in mature sperm. The different membrane domains appear sequentially during sperm morphogenesis in the testis and during later passage through the epididymis. To determine when diffusion barriers become functional during sperm development, we examined the diffusion of two proteins that are expressed on the cell surface of developing spermatids and become segregated to different plasma membrane domains during the course of spermiogenesis. Both proteins exhibited rapid lateral diffusion throughout spermiogenesis, even after they become localized to specific regions of the surface membrane. These results suggest that barriers to membrane diffusion form concomitantly with membrane domains during spermiogenesis