Electric porcelain insulators refer to porcelain electric insulating materials.
[Classified by voltage level]: high voltage, low voltage
【Production Capacity】
The role of insulators is directional, which was discovered in fruit fly experiments. After inserting the transposon gypsy into the yellow locus y of Drosophila (D. melanogaster), the y gene in some tissues will be inactivated, but the y gene in some tissues is still active. The reason lies in the end of the transposon gypsy There is a sequence of insulators. When gypsy is inserted at different positions of the "/ locus, it has different effects on gene activity. This is because the activity of the y gene is regulated by four enhancers. When the insulator is inserted just upstream of the promoter, it blocks the activation of the gene in the wing blade and body cuticle tissues (from upstream). Enhancer), but does not block the expression of the y gene (enhancers from downstream) in bristle (bristles) and farsal claws (farsal claws) tissues.
Since some enhancers are located upstream of the promoter and some are located downstream, the effect of the insulator does not depend on the relative position of the insulator and the promoter. Therefore, the reason for the directionality of the insulator effect has not really been clarified. Two loci have been found to affect the function of insulators in a trans-activation manner. The nucleoprotein encoded by the gene S2J (Hw) of the suspended high-voltage glass tempered insulator recognizes the insulator, and the insulator has an insulating effect after being combined with it. When the gene is mutated, although an insulator is inserted into the y locus, the insulating effect is lost, and y is expressed in all tissues. The other locus is mod(mdg 4). After this gene is mutated, its effect is just opposite to that of Su(Hw), that is, these mutants all enhance the insulation effect, so that the insulation effect of the insulator is no longer directional and expands , Which is to block the effect of enhancers on the upstream and downstream sides. There is an explanation that Su (Hw) first combines with the insulator DNA to make the insulator have an insulating effect. The combination of mod (mdg4) and Su (Hw) makes the insulator lose its insulating effect; the abrupt mod (mdg4) cannot be combined with Su (Hw), so the insulator enhances the insulation effect.
