A note on the inheritance of eye pattern in beans and its relation to type of vine

Ohne Zusammenfassung

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A note on the inheritance of eye pattern in beans and its relation to type of vine

     

FETAL DEVELOPMENT: THE EFFECTS OF MATURATION ON IN VITRO PROTEIN SYNTHESIS BY MOUSE BRAIN TISSUE

—The elucidation of the translational regulatory events which function during the critical fetal and neonatal period is an important prerequisite to our understanding of normal, as well as abnormal, brain growth and differentiation. Brain cell suspensions and cell-free homogenates were employed to study the protein synthetic activity during the maturation of fetal- neural tissue. The results clearly demonstrated that while neural tissue from 1-day postnatal mice was 10 times more active in protein synthesis than brain tissue from adult mice, the former was many fold less active in translational events than fetal neural tissue from 13-day post-zygotic mice. Fetal polypeptide synthetic activity was found to decrease from the 13th day to the 19th day post-zygotic. This decrement in the translational activity was not due to amino acid availability or pools, or to differences, quantitatively or qualitatively, in polysome concentrations. The enhanced rate of protein synthetic activity measured with neural tissue from 13-day post-zygotic mice was shown to be due to an increase in rate of protein synthesis and not to an enhanced rate of protein degradation.     

The synthesis and activity of tyrosinase during development of the frog Rana pipiens

We have established by radioimmunoprecipitation that tyrosine-DOPA oxidase (TDO, tyrosinase) [EC 1.14.18.1] is first synthesized by frog embryos at the early neurula stage soon after embryonic induction of the neural plate by the underlying chordamesoderm. The DOPA moiety of the enzyme, at the time of its first appearance, is almost inactive enzymatically and can be activated by mild proteolysis (with trypsin). A very large increase in the amount of active DOPA oxidizing enzyme (without trypsinization) is observed at hatching (stage 21), and this is accompanied by melanin deposition in pigment cells. The tyrosine moiety of the enzyme is also partially inactive at the time of first synthesis, but the ratio of active to inactive enzyme remains approximately constant throughout early development. DOPA decarboxylase enzymatic activity is first detected at neurula stage, and this activity is accompanied by the first appearance of catechol amines.