OCCURRENCE AND POSSIBLE FUNCTIONS OF MITOCHONDRIAL DNA IN ANIMAL DEVELOPMENT

Publisher Summary This chapter discusses the occurrence and possible functions of mitochondrial (mt) DNA in animal development. mt DNA of amphibians and sea urchins has densities similar to mammalian mt DNA. However, the density of avian mt DNA—chick, duck, and pigeon—is somewhat higher. Mitochondria from mammalian embryonic tissues in the later stages of organogenesis contain an elevated amount of mt DNA per milligram mitochondrial protein. As it is difficult to get sufficiently pure mitochondrial preparations from small amounts of embryonic tissues these values may be too low. The significance of extrachromosomal genome for embryonic animal development indicates that the oocytes with an unusually high proportion of cytoplasm contain an unusually large number of mitochondria compared to somatic cells of the same organism. The high percentage of extrachromosomal DNA present in these oocytes apparently results from the numerous mitochondria rather than from high mt DNA content per mitochondrion.