Sex-linked difference in DNA content of a polytene chromosome in Prodiamesa (Chironomidae).

The chironomid Prodiamesa olivacea possesses 3 pairs of chromosomes. The underreplication of the right arm in the polytene 3rd was presented earlier and is here shown to affect in females the cell nuclei of salivary glands. Malpighian tubules and the hindgut. The same somatic nucleic in males exhibit also a polytene 3rd with specific characteristics inasmuch as it contains half the relative DNA value of the female nuclei (3% instead of 6% complemental portion). - In male meiocytes the two partners in each of the 3 diakinetic bivalents were recognized to be homomorphic. In view of this morphological criterium the polytene situation in males must be due either to an unknown elimination process or to the underreplication of both right arms and further one left arm of the 3rd chromosomes. The latter model interprets the elements of the 3rd pair as differently polytenizing heterosomes in P. olivacea.