Complexity and specificity of polysomal poly(A+) RNA in mouse tissues

Area of Science:

• Molecular Biology
• Genomics
• RNA Biology

Background:

• Polysomal poly(A+)RNA plays a crucial role in gene expression.
• Understanding tissue-specific RNA complexity is vital for developmental and physiological studies.

Purpose of the Study:

• To estimate the base sequence complexity of polysomal poly(A+)RNA in mouse embryo, brain, and liver.
• To investigate the uniqueness of genes coding for these RNA sequences.
• To compare the abundance classes of poly(A+) sequences across different tissues.

Main Methods:

• Hybridization of homologous complementary DNA (cDNA) to polysomal poly(A+)RNA.
• Annealing of cDNA with excess total mouse embryo DNA to identify unique coding genes.
• Heterologous hybridization experiments to compare poly(A+) sequences between tissues.

Main Results:

• Sequence complexity estimates: mouse embryo (7 x 10^9 daltons), brain (1.5 x 10^10 daltons), and liver (7 x 10^9 daltons).
• Genes for polysomal poly(A+) sequences were found to be unique.
• High abundance poly(A+) sequences differed between tissues, but at least 55% of poly(A+)RNA was shared across tissues.

Conclusions:

• Mouse tissues exhibit distinct yet significantly overlapping sets of polysomal poly(A+)RNA.
• The findings suggest a substantial conservation of polyadenylated RNA populations across different cell types.
• This shared RNA pool likely contributes to fundamental cellular functions and organismal development.