Studies on mammalian chromosomes. Final report. [Satellite DNA sequences in rat cells] Page: 7 of 13
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This apparent location of the main band and satellite DNAa was also
suggested by Gtomsa staining of chromosomes treated with 0.007 N NaOH .
Staining was intense in the kinetochores of all chromosomes and in the short
arms of most of the chromosomes. Three pairs of chromosomes were intensely
stained at the kinetochore only. The long arms of chromosomes were lightly
stained. This staining pattern is consistent with the idea that satellite DNAs
appear as constitutive heterochromatin in well-defined locations in the chromo-
somes.
The location of the satellite DNAs has been confirmed by in situ
hybridization with 3H RNA transcribed from satellite DNA .
Finally, we have measured by cytospectrophotometry the amount of
DNA per sperm (genome) for seven species. We have used mouse sperm as a
standard for estimating the absolute amount of DNA per sperm in the kangaroo
rats, using the value of 3.0 pg/mouse sperm established by others. The
values for the seven species of kangaroo rats are:
_ D. ordii 4.4 pg
D. merriami 2.2 pg
D. desertil 4.0 pg
D. spectabulis 3.0 pg
P. panimintinus 2.8 pg -
D. ingens 2.8 pg
D. microns 3.2 pg
It is clear that there is no precise relationship between the amount of
satellite DNA in a species and the total amount of DNA In its genome. It is
still notable that D. ordii has the most satellite DNA and the largest DNA
value for its genome. The genus is also remarkable for the range of DNA
values per genome. The genus covers a two-fold range and contains species
with the least (2.2 pg) and the most (4.4 pg) DNA among mammals.
In collaboration with F. Hatch and J. Mazrimas of the Lawrence
Livermore Laboratory, we have found that the HSa satellite of kangaroo rat
cells is unusually rich in the base 5' methyl cytosine. This satellite is
localized in chromosome kinetochores in 32 of the 35 chromosomes in the
cell line.3
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Prescott, D.M. Studies on mammalian chromosomes. Final report. [Satellite DNA sequences in rat cells], report, September 1, 1975; Boulder, Colorado. (https://digital.library.unt.edu/ark:/67531/metadc1055557/m1/7/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.