Change in quantity and size distribution of small circular DNAs during development of chicken bursa.

Abstract

Small circular DNA ranging in contour length from 0.06-3.5 .mu.m were isolated from bursas of 19 day chicken embryos and 4 to 5 wk old chickens. Small circular DNA is present in bursas of 19 day embryos at approximately 0.2 molecules/cell and is very heterogeneous, lacking distinct size classes; most molecules have contour lengths of less than 0.4 .mu.m. Small circular DNA is present in bursas of 4-5 week old chickens at about 4 molecules/cell, and although this DNA is still heterogeneous, it contains a major distinct class of molecules 0.8 .mu.m in size. These small circular DNA may be products of developmental gene rearrangements occurring in the chromosomal DNA of lymphocytes in the bursa.