Renin granules were partially purified from rat kidney cortex, and a storage form of renin in the granules was examined. Renin granules were isolated by discontinuous Percoll density gradient centrifugation followed by continuous Percoll density gradient centrifugation. The partially purified fraction was free from mitochondria and microsomes, as judged by the absence of marker enzymes of these...

Erythroid progenitor cells, CFU-E (colony-forming-unit-erythroid), were isolated to practical homogeneity by a combination of three enrichment procedures. CFU-E were generated in large amounts in spleens of mice previously bled and treated with the erythropoiesis-suppressing drug thiamphenicol. The average CFU-E concentration in spleens from mice 4 d after the thiamphenicol-treatment was 10%. T...

Cells of Dunaliella tertiolecta from the log phase of growth were broken by rapid extrusion at low pressure through a Yeda press and the chloroplasts were isolated by centrifugation through a Percoll gradient. Osmolarity of the growth media, the suspending media, and the Percoll gradient was kept identical to minimize change in chloroplast volume and mitochondrial entrapment. The isolated intac...

Neurosecretory granule lysate from bovine posterior pituitary was shown to contain both carboxypeptidase B and amidating activities. The former sequentially releases COOH-terminal basic residues from the oxytocin biosynthetic precursor fragment oxytocinyl-GKR (CYIQNCPLGKR) to form oxytocinyl-GK and then oxytocinyl-G. The amidating enzyme converts the resulting oxytocinyl-G into oxytocin (CYIQNC...

OBJECTIVE To compare the percentage of sperm tail membrane swelling under hypo-osmotic conditions between sperm treated with pentoxifylline and 2-deoxyadenosine. DESIGN Experimental in vitro study. MATERIAL AND METHOD Thirty normal semen samples from male partners of infertile couples were collected. After sperm preparation by two-layer Percoll gradient method, each sperm sample was divided...

Cryptosporidium oocysts were concentrated by an ether-phosphate-buffered saline sedimentation technique and then separated by density gradient centrifugation. This two-step method yielded highly concentrated oocysts largely free of bacteria and fecal debris.