| Popis: |
Relative DNA content during the polytenization of the salivary gland nuclei of Chironomus thummi was measured by cytophotometric and cytofluorometric methods. To estimate polyteny degree, DNA content was calculated in hemocyte and spermatocyte nuclei. Chromosome polytenization is associated with the 10th-12th replication rounds. There are 4-5 replication rounds in the 1st instar, 2-3 rounds in the 2nd instar, the 3rd and the 4th instars have 1-2 rounds each. From early postembryonic development, larvae already have salivary gland nuclei representing two polyteny classes (2-2-2-4c), this heterogeneity being retained in all instars. Approximate DNA content is 0.51-0.58 picogram per a diploid set. |
