Mitochondrial matrix
The cytosolic, intermembrane space, compartment has a water content of 3.8 μl/mg protein, while the mitochondrial matrix 0.8 μl/mg protein. It is not known how mitochondria maintain osmotic balance across the inner mitochondrial membrane, although the membrane contains aquaporins that are believed to be conduits for regulated water transport. Mitochondrial matrix has a pH of about 7.8. Mitochondrial DNA was discovered by Nash and Margit in 1963. One to many double stranded mainly circular DNA is present in mitochondrial matrix. Mitochondrial DNA is 1% of total DNA of a cell. It is rich in Guanine and Cytosine content. Mitochondria of mammals have 55s ribosomes.
Aurochs
The first complete mitochondrial genome (16,338 base pairs) DNA sequence analysis of "Bos primigenius" from an archaeologically verified and exceptionally well preserved aurochs bone sample was published in 2010, followed by the publication in 2015 of the complete genome sequence of "Bos primigenius" using DNA isolated from a 6,750-year-old British aurochs bone. Further studies using the "Bos primigenius" whole genome sequence have identified candidate microRNA-regulated domestication genes