On the origins of esterases

Comparisons among the primary sequences of five cloned eukaryotic esterases reveal two distinct lineages, neither bearing any significant overall sequence similarity to the functionally related serine protease multigene family. We have not eliminated the possibility that the esterases may have residual conformational similarities to the serine proteases. However, our profile analysis and analyses of the predicted conformations of the esterases reveal little similarity to the serine proteases. Four of the esterase proteins share 27%-53% overall sequence similarity and evidence of a catalytic mechanism involving the same Arg- Asp-Ser or His-Asp-Ser charge relay. We propose that these four esterases, three of them cholinesterases, form part of a multigene family essentially separate from the serine proteases.      

Morphological and electrophysiological properties of the electromotoneurones of the electric ray Torpedo marmorata in vivo and in in vitro brain slices

The morphology of the adult electromotoneurones of the electric ray Torpedo marmorata has been investigated by intracellular injection of horseradish peroxidase. The results show particularly small dendritic fields, poor dendritic branching, and the existence of two distinct types of dendrites. The electrophysiological data demonstrate that the electromotoneurones behave similarly in vivo and in in vitro brain slices. Observations on spontaneous and stimulus-evoked postsynaptic potentials suggest quantal release of transmitter in the Torpedo central nervous system.     

Assembly of splicing complexes on exon 11 of the human insulin receptor gene does not correlate with splicing efficiency in-vitro

Background  

Incorporation of exon 11 of the insulin receptor gene is both developmentally and hormonally-regulated. Previously, we have shown the presence of enhancer and silencer elements that modulate the incorporation of the small 36-nucleotide exon. In this study, we investigated the role of inherent splice site strength in the alternative splicing decision and whether recognition of the splice sites is the major determinant of exon incorporation.     

An algorithm for angiographic estimation of blood vessel diameter.

This study was carried out in an attempt to develop an objective and robust method for measuring changes in the diameters of small blood vessels from X-ray angiographic images. Recognizing potential problems with edge detection methods applied to cylindrical vessels in which the contrast diminishes as the boundary is approached, we have attempted to utilize the X-ray absorbance data across the entire cross section of the vessel. Then, assuming a cylindrical geometry, the absorbance data are fit to the cylindrical absorbance function by use of nonlinear regression analysis. The method was tested and calibrated using glass tubes filled with various concentrations of contrast medium. The diameters of small pulmonary arteries were estimated by applying the method of angiograms obtained from an isolated dog lung lobe. The structure of the residuals obtained after the fitting procedure was analyzed to test the appropriateness of the model for use with images of vessels. The results suggest that this approach will have utility for systematically quantifying vessel dimensions.