Electrophoretic Studies of Intact Nuclei Isolated from Mammalian Brain. II: Electrokinetic characteristics following treatment and comparison of glial and neuronal nuclei

Abstract

1) The electrokinetic properties of glial nuclei-enriched and neuronal nuclei-enriched fractions isolated from rabbit brain are studied and compared with those of rat cerebral cortex nuclei. While both fractions exhibit behaviour similar to that of rat cerebral cortex nuclei, the peak velocity in an electrophoretic field of the rabbit nuclei is higher than that of the rat cerebral cortex nuclei. In addition, the velocity of the glial nuclei is found to be significantly higher than that of the neuronal nuclei.

2) Treatment with DNAase of intact nuclei isolated from rat cerebral cortex results in a large decrease in the velocity of nuclear migration and a heterogeneity of the population distribution, while similar treatment with pancreatic RNAase has little effect. Increased time of incubation with RNAase results in a decrease of the observed velocity. Treatment of the nuclei with a combination of DNAase and RNAase results in a loss of nuclear morphology and a very large decrease in electrophoretic mobility.

3) Treatment of nuclei with pronase results in a very large decrease in nuclear mobility, and is associated with structural changes in the nuclei.

4) Electrophoresis of nuclei following heparin treatment results in an increase in the observed velocity of migration of the nuclei, while similar electrophoresis of nuclei treated with spermidine results in a decresae in the observed velocity of migration.

5) Treatment of nuclei with a brain specific protein does not yield any apparent change in the nuclear migration.

6) The zeta potential and surface charge density of the nuclei are calculated for each of these treatments.

7) the effects of various treatment on nuclear morphology are presented.

8) From the results obtained it is suggested that the surface charges in nuclei arise from at least two different types of surface structure. One type of charge apparently arises from some amphoteric structures, while the other might be associated with some DNAase-labile structures.