Abstract
The patterns of proteins synthesized in developing Spisula embryos and larvae were compared with in vitro translation products by one-dimensional gel electrophoresis. Major changes in the in vivo pattern occur at fertilization; these are regulated at the translational level (Rosenthal, Hunt, and Ruderman, 1980, Cell 20, 487-494). The pattern is further altered by midcleavage, and subsequent development is accompanied by frequent changes in the kinds of proteins made. By midcleavage many of the in vivo changes are paralleled by alterations in mRNA levels. Three cDNA clones containing developmentally regulated, nonmitochondrial sequences were isolated from a library constructed from veliger larval RNA. Clone 3v4 encodes alpha-tubulin. Clone 12v4 encodes a 35,000-D protein of unknown function. The protein product of clone 10v8 has not been identified. The concentration of alpha-tubulin RNA is relatively low through midcleavage, increases by the swimming gastrula stage, and is maintained at a moderately high level throughout larval development. 10v8 and 12v4 RNAs first appear in trochophore larvae; their concentrations peak 10-12 hr later, and then decline. The proportions of alpha-tubulin and 10v8 RNA that are translated vary with developmental stage. During early cleavage very little alpha-tubulin RNA is on polysomes; in swimming gastrulae 64% of this mRNA is polysomal. Seventy percent of 10v8 RNA is translated in the trochophore larva, while only approximately 40% is polysomal in the 21-hr veliger. These results show that translational regulation may be superimposed on changes in cytoplasmic mRNA concentrations to determine the level of gene expression during embryogenesis.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.