Assume liver and kidney tissues from the same mouse each contain about 10,000 species of cytosolic mRNA, but only about 25% of these are common to the two tissues.

Suggest an experimental approach that might be used to establish that some of the mRNA molecules are common to both tissues, but others are not.

Select all that apply.

-Southern blotting could be used to measure the fraction of common mRNA molecules.

-Common mRNA could be measured using the yeast two-hybrid system.

-Northern blotting could be used to measure the fraction of common mRNA molecules.

-DNA microarrays could be used to compare the mRNAs produced in the two tissues.

-Common mRNA could be measured using nuclear run-on transcription.

The correct answers are:

• Northern blotting could be used to measure the fraction of common mRNA molecules.

Northern blot is a technique used to study gene expression by detection of mRNA in a sample. This technique allows observation of a particular gene's expression pattern between tissues, so it can be used to observe the common expression in both, liver tissue mRNA and kidney tissue mRNA.

• DNA microarrays could be used to compare the mRNAs produced in the two tissues.

DNA microarray can be used to detect DNA, or detect RNA in order to measure the expression levels of certain genes. Microarray-based gene expression profiling (RNA) can be used to identify genes whose expression is different in different tissues.