higher using U6B (mean NRQ of blood: 2384.53). Applying
miR92 and miR374, blood samples showed a mean NRQ of 32.32.
Regarding both semen markers and skin marker miR203, an
unambiguous identification of the cell type’s origin was only
possible if both validated endogenous controls were used as
normalizers. Data of semen-specific marker miR135b generally
showed higher expressions when using miR92 and miR374 to
correct the relative quantities measured (Fig. 1). The NRQs for
blood clustered around 0.005, while the values for the other cell
types showed higher expressions (highest mean NRQ of 19.95 in
semen samples). This indicates that miR135b is not specifically
expressed in semen but rather in epithelial cells. Data for skinspecific
marker miR203 revealed similar results showing high
expression values in semen, saliva and skin samples. In comparison,
NRQs of all sample types clustered in a narrow range when
data were corrected with U6B. In these cases, a positive cell type
identification was not possible. Both saliva markers (miR205 and
miR658) did not give any results probably due to technical
problems.