  We use recently developed efficient versions of the configuration interaction
method to perform {\em ab initio} calculations of the spectra of superheavy
elements seaborgium (Sg, $Z=106$), bohrium (Bh, $Z=107$), hassium (Hs, $Z=108$)
and meitnerium (Mt, $Z=109$). We calculate energy levels, ionization
potentials, isotope shifts and electric dipole transition amplitudes.
Comparison with lighter analogs reveals significant differences caused by
strong relativistic effects in superheavy elements. Very large spin-orbit
interaction distinguishes subshells containing orbitals with a definite total
electron angular momentum $j$. This effect replaces Hund's rule holding for
lighter elements.
