For Internal Transcribed Spacer?

Internal transcribed spacer (ITS) is a piece of nonfunctional RNA located between structural ribosomal RNAs (rRNA) of a common precursor transcript, which is especially useful for elucidating relationships among congeneric species and closely related genera (Hao et al., 2010).

Are spacers transcribed?

In bacteria, spacer DNA sequences are only a few nucleotides long. ... In ribosomal DNA, there are spacers within and between gene clusters, called internal transcribed spacer (ITS) and external transcribed spacers (ETS), respectively. In animals, the mitochondrial DNA genes generally have very short spacers.

What is the difference between ITS1 and ITS2?

Conversely, there are two ITSs in eukaryotes: ITS1 is located between 18S and 5.8S rRNA genes, while ITS2 is between 5.8S and 28S (in opisthokonts, or 25S in plants) rRNA genes. ITS1 corresponds to the ITS in bacteria and archaea, while ITS2 originated as an insertion that interrupted the ancestral 23S rRNA gene.