Chromosomes of fossilized Metasequoia from early Oligocene of Siberia

Nuclear preservation in the cartilage of the Jehol dinosaur Caudipteryx

“…A similar method using another stain (the Feulgen stain) which binds to the sugar-phosphate backbone of the DNA molecule was successfully applied to Eocene leaf and fruit tissues and clearly stained the nuclei in red 42,43 . More recently, some exquisitely preserved plant anaphasic chromosomes from the Oligocene were stained using this same histochemical method and the staining was clearly located within the chromosomes only (not within the cytoplasm nor the cell membrane), demonstrating that the staining was specific and that the method worked 7 . Other examples of histochemical stains were applied to a variety of fossils tissues and cells from different localities, again showing a similar reactivity in the fossil tissues when compared to analogous extant tissues (e.g., ref.…”

“…Even though hematoxylin binds to DNA in extant cells, H&E alone cannot be considered a powerful enough stain to suggest that ancient DNA is preserved in this fossilized material (for this, more specific DNA stains like the Feulgen stain, or DNA fluorescent dyes like Propidium Iodide or DAPI would be preferred; e.g., refs. 6,7,35 ). The H&E staining observed here does however show that differences in chemistries between the chondrocyte cytoplasm and the nucleus were preserved for millions of years, still retaining the ability to properly interact with standard histochemical stains.…”

“…These examples are numerous and include nuclei from permafrost-preserved Cenozoic mammals, Mesozoic dinosaurs, various Cenozoic, Mesozoic, and Paleozoic plants, and even embryo-like fossil cell clusters that are more than 600 Million years (My) old (e.g., refs. [3][4][5][6][7] ). Recent taphonomy experiments on plants and algae have shown that nuclei are surprisingly stable and that nuclear decay is much slower than originally thought in some conditions 8,9 .…”

“…One of the finest levels of nuclear preservation is exemplified by fossilized mitotic chromosomes in permineralized plants 3,4,7,10,11 . In living organisms (Eukaryotes and Archaea), chromosomes represent the highest level of condensation of chromatin, which is composed of condensed DNA molecules coiled around histone proteins (e.g., ref.…”