Abstract
The amount of DNA was microphotometrically estimated in nuclei of embryonal and differentiated cells of Cyclops strenuus using the two-wave-length technique of Patau. The DNA content of cells in an adult Cyclops falls into classes corresponding a diploid, tetraploid, octoploid and 16-ploid chromosome complement. These data are consistent with the generally accepted hypothesis of a constant amount of DNA per chromosome complement. Alterations of the DNA content, which do not fit the concept of DNA constancy, occur at two particular stages of embryogenesis. An amount of DNA exceeding the theoretical value by about 5C is synthesized in the oocyte nuclei and in nuclei of the 16-cell stages respectively. The excessive synthesis and elimination of DNA does not interfere with the development of the embryo. It is concluded that two types of deoxyribonucleic acid are present in chromosomes: a DNA which amount does not vary during the life span of a cell and a DNA which varies in amount. The latter one is possibly limited to heterochromatic segments of the chromosomes.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
