The osmolarity and density of colloids used to prepare spermatozoa for assisted reproduction may affect sperm quality in the resultant preparation. In this study, two osmolarities of Androcoll-E for single-layer or density gradient centrifugation of stallion spermatozoa were compared: "normal" (320 mOsm) or "high" (345 mOsm). Mean yields for the two centrifugation techniques did not differ betw...

Plasma membrane-enriched preparations from scrapie-infected and healthy hamster brains were detergent-extracted, then separated by equilibrium density centrifugation in continuous Nycodenz gradients. The highest level of infectivity was always associated with the insoluble residue which sedimented through 40% Nycodenz. The degree of aggregation in these insoluble complexes varied depending upon...

Microbodies, designated as peroxisomes because of their enzyme complement, have been isolated from spinach leaves. After grinding leaves in 0.5 M sucrose, the peroxisomes were removed with the broken chloroplast fraction by differential centrifugation. During sucrose density gradient centrifugation, the peroxisomes banded in about 1.9 M sucrose and were separated from mitochondria and chloropla...