Complex sentence: Constitutive heterochromatin is found more commonly in the periphery of the nucleus attached to the nuclear membrane, which concentrated the euchromatic DNA in the center where it can be actively transcribed.
Split into simpler sentences: Constitutive heterochromatin is found more commonly in the periphery of the nucleus attached to the nuclear membrane. This concentrates the euchromatic DNA in the center of the nucleus where it can be actively transcribed.