REGULATION OF POLYPEPTIDE SYNTHESIS DURING EARLY EMBRYOGENESIS IN THE MARINE MUD SNAIL, ILYANASSA OBSOLETA.
Item
-
Title
-
REGULATION OF POLYPEPTIDE SYNTHESIS DURING EARLY EMBRYOGENESIS IN THE MARINE MUD SNAIL, ILYANASSA OBSOLETA.
-
Identifier
-
AAI8023749
-
identifier
-
8023749
-
Creator
-
MCCARTHY, MARY ELLEN VINCENTIA.
-
Contributor
-
Dr. Jack Collier | Louis G. Moriber
-
Date
-
1980
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, General
-
Abstract
-
The goal of these studies was to describe the regulation of gene expression during early development in a spiralian embryo through an analysis of the mechanisms by which stage-specific changes in polypeptide synthesis are accomplished.;The approach was a comparison by two-dimensional electrophoresis, of polypeptides synthesized during early cleavage, mesentoblast and gastrula stages. The relative contribution of maternal and embryogenic transcription to changes in polypeptide synthesis throughout this period was assessed by comparing the polypeptides made by normal and actinomycin D-treated embryos. The mechanisms by which ooplasmic segregation controls polypeptide syntheis were investigated by an analysis of polypeptide synthesis in the isolated cytoplasmic polar lobe and lobeless embryos.;The results presented here show that significant changes in polypeptide synthesis occur as early as the twenty-five cell (mesentoblast) stage that are correlated with the determinative events of this period in development. Further changes in polypeptide synthesis occur at gastrulation.;The analysis of polypeptide synthesis in embryos reared in actinomycin D has demonstrated that (1) all of the polypeptides made during early cleavage and detected by two-dimensional electrophoresis are translated from oogenic mRNAs, (2) stored oogenic mRNP is activated at the mesentoblast and gastrula stages, (3) the translation of most species of maternal mRNA is regulated by transcriptionally independent mechanisms, (4) oogenic mRNA remains a primary source of transcripts for protein synthesis through gastrulation and (5) embryogenic mRNA is first translated at the mesentoblast stage. It is postulated that a group of regulatory genes exist whose transcripts, directly or indirectly, repress the translation of specific oogenic mRNAs.;An analysis of polypeptides made by the isolated polar lobe and the lobeless blastomeres has shown that (1) the polar lobe contains at least 300 species of maternal mRNAs, (2) the polar lobe and lobeless blastomers translate the same oogenic mRNAs, (3) the polar lobe is able to activate stored oogenic mRNAs and regulates the translation of some maternal mRNAs, (4) the effect of the polar lobe on polypeptide synthesis is delayed until the mesentoblast stage and (5) at the mesentoblast and gastrula stages, it is postulated that factors in the polar lobe cytoplasm (a) regulate the activation of oogenic mRNA, (b) activate the synthesis or translation of embryogenic mRNA and (c) control the expression of regulatory genes whose products repress the translation of specific maternal mRNAs.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Biology
