Brain membrane preparations contain tubulin that can be extracted with Triton X-114. After the extract is allowed to partition, 8% of the total brain tubulin is isolated as a hydrophobic compound in the detergent-rich phase. Cytosolic tubulin does not show this hydrophobic behaviour since it is recovered in the aqueous phase. Membrane tubulin can be released by 0.1 M Na2 CO3 treatment at pH > or = 11.5 in such a way that the hydrophobic tubulin is converted into the hydrophilic form. These results suggest that tubulin exists associated with some membrane component that confers the hydrophobic behaviour to tubulin. If the tissue is homogenized in microtubule-stabilizing buffer containing Triton X-100, the hydrophobic tubulin is isolated from the microtubule fraction. This result indicates that the hydrophobic tubulin isolated from membrane preparations belongs to microtubules that in vivo are associated to membranes. Therefore, hydrophobic tubulin (tubulin-membrane component complex) can be obtained from membranes or from microtubules depending on the conditions of brain homogenization.
The aim of the present study was to analyze the variation of esterase activity as well as the expression patterns of isozymes by isoelectric focusing on polyacrylamide gels (IF-PAGE) and conventional polyacrylamide gel electrophoresis (PAGE). Esterase activity and isoforms were analyzed on total proteins from 9 isolates of Beauveria bassiana, from different hosts and geographic areas from the State of Guerrero, Mexico. Total proteins were separated by IF-PAGE and PAGE, in order to characterize the activity and isoelectric points of the esterase isoforms detected on different isolates. Electrophoretic analysis from 9 isolates of Beauveria bassiana, revealed a polymorphic pattern in terms of esterases activity and the presence of isozymes, showing a total of 10 different isoforms with variations in both the activity and isoelectric point. Each isolate showed between 3-6 different isozymes. Cluster analysis derived from the Jaccardś coefficients showed a significant association between the presence-absence of esterase isoforms and the geographical origin of the Beauveria bassiana isolates. We conclude that the use of this methodology for functional detection combined with PAGE and IF-PAGE, can be an excellent tool for biochemical characterization of isolates and further impact evaluation of artificial epizootics derived from Biological control programs.
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