Scanning Electron Microscopic Features of Spleen in the Rat and Human: A Comparative Study

The marginal zone, white pulp and red pulp of rat and human spleen were studied by scanning electron microscopy and were compared. The marginal zone was observed in both species. The arterial termination in the marginal zone was quite different between both species. The follicular arteries terminated at the boundary of the white pulp and formed a vascular net regarded as the marginal sinus in rat. On the other hand, numerous arterial termini of the follicular and sheathed arteries were scatteringly found in the marginal zone in man. The central artery was surrounded with flat reticular cells in rat and human spleen. In the red pulp of rat, the arterial termini were funnel-shaped or tubular. The sheath of the sheathed arteries of man revealed a circumferential lamellar structure consisting of flat reticular cells, and most free cells of the sheath were washed away by perfusion

Immobilization of single strand DNA on solid substrate

Thin films based on Layer-by-Layer (LbL) self assembled technique are useful for immobilization of DNA onto solid support. This communication reports the immobilization of DNA onto a solid support by electrostatic interaction with a polycation Poly (allylamine hydrochloride) (PAH). UV-Vis absorption and steady state fluorescence spectroscopic studies exhibit the characteristics of DNA organized in LbL films. The most significant observation is that single strand DNA are immobilized on the PAH backbone of LbL films when the films are fabricated above the melting temperature of DNA. DNA immobilized in this way on LbL films remains as such when the temperature is restored at room temperature and the organization remains unaffected even after several days. UV-Vis absorption spectroscopic studies confirm this finding.Comment: Eight pages, five figure

Enzymatic Digestion of Single DNA Molecules Anchored on Nanogold-Modified Surfaces

To study enzyme–DNA interactions at single molecular level, both the attachment points and the immediate surroundings of surfaces must be carefully considered such that they do not compromise the structural information and biological properties of the sample under investigation. The present work demonstrates the feasibility of enzymatic digestion of single DNA molecules attached to nanoparticle-modified surfaces. With Nanogold linking DNA to the mica surface by electrostatic interactions, advantageous conditions with fewer effects on the length and topography of DNA are obtained, and an appropriate environment for the activities of DNA is created. We demonstrate that by using Dip-Pen Nanolithography, individual DNA molecules attached to modified mica surfaces can be efficiently digested by DNase I