IDENTIFICATION OF CHANGES IN THE CONTENT OF GUINEA-PIG BRAIN PROTEINS BETWEEN THE 30TH PRENATAL AND THE 75TH POSTNATAL DAY

The whole guinea-pig brain was studied during prenatal, as well as postnatal development. The percentage of total proteins and their electrophoretic pattern on polyacrylamide gel were determined for each brain. From the 30(th) until the 48(th) day of gestation, when guinea-pig brain mass rapidly increased, the protein concentratton decreased 1.4 times. From the 48(th) until the 63(rd) day (parturition), when the increase of the brain mass was relatively slow, protein concentration increased 1.4 times. During the postnatal period, from parturition until adulthood, the total protein level increased by 0.5% only. Electrophoretic patterns of the total brain proteins showed that, from the 30(th) until the 48(th) day, the levels of all histone fractions (H-1, H(2)A, H-2B, H-3 H-4) decreased, at a rather high rate. From the 48(th) until the 63(rd) day, the level of mast histone fractions changed remarkably little. However, H-1 histone level increased during this period more than any other protein fraction - the increment being sixfold. The myelin basic protein (MBP) level began to increase from the 48(th) day and continued to increase until parturition, at the same or approximately the same rate as the HI histone. Following parturition MBP gain accelerated. MBP level in the adult brain was up to eight times higher than in the brain of new-born guinea-pigs.