THE NUCLEOPROTAMINE OF TROUT SPERM

The nucleoprotamine of trout sperm can be extracted completely with 1 M sodium chloride. On reducing the salt concentration to 0.14 M, physiological saline, the nucleoprotamine precipitates in long, fibrous strands. When the nucleoprotamine, dissolved in M NaCl, is dialyzed all the protamine diffuses through the membrane leaving behind highly polymerized, protein-free desoxyribose nucleic acid. The nucleoprotamine constitutes 91 per cent of the lipid-free mass of the sperm nucleus. While nucleoprotamine is being extracted by M NaCl a stage is reached at which the sperm chromosomes are clearly visible.     

Structural and histochemical study of the effect of 1,25-dihydroxyvitamin D3 on long-bone growth center in suckling mice

The in vivo effects of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] on cellular structure and response, matrix metachromasia and mineralization have been studied in the epiphysis and growth plate of humeri in normal neonatal mice. A relatively low dose of the metabolite, 50 ng/kg body weight, significantly increased the overall size of humeral growth plate, the zone of proliferating cells and that of hypertrophic chondrocytes. The response of the tissue to the metabolite changed with the increase in dose administered so that it was only the zone of proliferation that still showed increases in size in comparison to untreated controls. 1,25 (OH)2D3 led to an increase in the metachromatic reaction of the cartilage matrix in the chondroblastic zone, and to marked increase in matrix mineralization in the hypertrophic zone. Qualitative changes were also noted in the structure of chondroblasts and hypertrophic chondrocytes. 1,25(OH)2D3 affected the osteoblastic and osteocytic populations of cells along the metaphysis and diaphysis of the humerus. High doses of 1,25(OH)2D3 brought about distinct atrophic changes in the above cells. Chondrocytes in the epiphysis were found to synthesize type I collagen and fibronectin. These findings indicate that excessive doses of 1,25(OH)2D3 in an intact growing animal affect the normal differentiative pathway of prechondroblasts and thereby affect long bone development.     

Pulse velocities in cylindrical,tapered and curved anisotropic elastic arteries

Modified Moens-Korteweg formulae have been developed for the pulse velocities in anisotropic elastic arteries of varying geometries. In particular, cylindrical straight, tapered and curved tubes have been considered. Numerical results indicate that the cylindrical tube formula can be applied in all cases and that the circumferential elastic modulus is the dominant elastic parameter.     

Self-referencing SPR-biosensors based on penetration difference of evanescent waves

SPR based biosensors register binding of analytes to the surface with immobilized receptors by measuring changes of the refractive index near this surface. An important task in the improvement of this measurement technology is a separation of signals, corresponding to the changes in the chemosensitive layer, from undesired contributions of bulk phase, for example, due to fluctuations of temperature, concentrations of solutes, pressure. The wavelength of the incident light influences strongly the penetration depth of the corresponding evanescent wave. This dependence was exploited here for compensation of the contribution of the bulk refractive index. It was performed using differential SPR measurements at two wavelengths with differing penetration depths. Theoretical analysis and numerical optimization of the suggested approach, named a Penetration Difference Self-Referencing SPR (PDSR-SPR), were performed. Experimental test was performed using 658 and 980 nm laser diodes. Over 20 times suppression of variations of bulk refractive index with magnitude up to 1000 μRIU was observed. Finally, PDSR-SPR approach was applied for monitoring of antibodies binding to the immobilized antigens.