Conformation Of Chloroplast Dna In Wheat Leaves

Sedimentation and electron microscopic studies have provided no evidence for the presence of circular DNA (deoxyribonucleic acid) in chloroplasts from wheat leaves. Electron microscopy of osmotically disrupted chloroplasts has revealed the presence of linear duplex filaments, some with a tertiary helicoidal configuration and possibly monostranded filaments. None of these structures was observed if the chloroplasts were previously treated with DNase (deoxyribonuclease), but the tertiary configuration was somewhat disorganized by RNase (ribonuclease).