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  • Author: R. Bauer x
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Abstract

Phase, pulse and steady-state measurements of ethanolic solutions of 4-methylumbelliferone with various water and hydrochloric acid contents were performed. A kinetic model is proposed and some parameters are determined.

Measurements of the polarization and the mean decay periods τ and τ of fluorescence components I and I parallel and perpendicular to the electric vector of plane polarized exciting light were performed for uranin dye solutions in glycerol diluted with methyl alcohol, ethyl alcohol and water. From these measurements the volume ν of the dye molecule together with its solvation shell and the limiting emission anisotropy r0 for solutions of various viscosities were calculated. Both ν and r0 appeared to be in general not constant and dependent on the nature of the solvent. If, as observed in one case, ν and r0o are substantially constant, a good agreement between experimental values τ/τ and τ/τ and those evaluated from the equations of JABLONSKI is obtained (τ being the mean duration of the fluorescence emitted in all directions).

Abstract

The mean fluorescence decay time for rhodamine 6G (donor) in the presence of malachite green (acceptor) has been investigated using a pulse fluorometer. The experimental results have been compared with theoretical ones obtained earlier [1].

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Abstract

The ceramide synthase (CerS) gene family comprises a group of highly conserved transmembrane proteins, which are found in all studied eukaryotes. The key feature of the CerS proteins is their role in ceramide synthase activity. Therefore, their original name ‘longevity assurance gene (Lass) homologs’, after the founding member, the yeast longevity assurance gene lag1, was altered to ‘CerS’. All CerS have high sequence similarity in a domain called LAG1 motif and a subset of CerS proteins is predicted to contain a Homeobox (Hox) domain. These domains could be the key to the multiple roles CerS have. CerS proteins play a role in diverse biological processes such as proliferation, differentiation, apoptosis, stress response, cancer, and neurodegeneration. In this review, we focus on CerS structure and biological function with emphasis of biological functions in the widely used model systems Caenorhabditis elegans and Drosophila melanogaster. Also, we focus on the accumulating data suggesting a role for CerS in lipid homeostasis.

Abstract

Chick helper factor (chf) negative chick embryo cells were exposed in the presence of DEAE-dextran to chromosomal DNA isolated from avian leukemic myeloblasts which had been induced by infection with the BAI-A strain of avian myeloblastosis virus (AMV) (subgroup B) . After several transfers, avian C-type virus production was observed in the cultures with electron micro­ scopy, although no alteration in the cell morphology was apparent.

Virus interference tests revealed that this virus was infectious and belonged to subgroup B of the avian RNA toumor virus (ATV) group. The virus induced nephroblastomas 2 months after intraperitoneal inoculation of chickens; no myeloblastosis was observed, however, and the virus could neither transform chick embryo cells in vitro nor induce wing web tumors in vivo. The nephroblastomas also produced virus which was again shown to be a member of subgroup B. From these results it was concluded that the virus transmitted in these experiments was avian myeloblastosis associated virus (MAV), an avian leukosis virus known to be present as a major component in AMV stocks.