  The observed strong dark-to-luminous matter coupling is described by a bias
relation between visible and dark matter sources. We discuss the bias which
emerges in the case where the topological structure of the Universe at very
large distances does not match properly that of the Friedman space. With the
use of such "topological" bias, we construct the Universal Rotation Curve (URC)
for spirals which occurs to be in a striking agreement with the empirically
known URC. We also show that the topological bias explains the origin of the
Tully-Fisher relation ($ L\sim V^{4}$) and predicts peculiar oscillations in
the URC with a characteristic length $\sim \sqrt{L}$.
