Questions: G to A and C to T substitutions, is this a rule ?
ohungnes at bioslave.uio.no
Tue Apr 12 09:51:54 EST 1994
Zhongguo Xiong (zxiong at arizvm1.ccit.arizona.edu) wrote:
: Dear Colleagues:
: Being not familiar with molecular evolution. I have been troubled with some of
: my data in RNA virus sequence. We are working on a small RNA virus and nearly
: complete the sequence of the viral RNA genome from cDNA clones. RNA viruses
: are known to be heterogenous (quasi-species), so it was not surprising to see
: nucleotide sequence variations when sequences are obtained from different
: clones. What was surprising was a consistent rule of sequence variaions. G is
: always subsituted with a A, or vice versa. C is always substituted with a T,
: or vice versa. But there is never a G to (C, T) change or vice versa.
In RNA, U is able to base pair with G to some extent, as well as to A. See?
T-C substitutions would appear on the complementary strand.
: Let me try to explain it a little better. We have found 16 nucleotide
: substitutions in about 1500 nucleotide of overlapping sequences. There are 11
: C to T or T to C substitutions and 5 G to A or A to G substitutions. We have
: not found any other possible substituions.
: Is there a theory describing the rule of nucleotide substitution during
: evolution? I feel very ignorant and hope someone can give me a pointer to how
: to explain my observation.
: Any comments or suggestions are welcome.
: Zxiong at arizvm1.ccit.arizona.edu
Olav Hungnes ohungnes at extern.uio.no
National Institute Phone (+47)22042200
of Public Health FAX (+47)22353605
More information about the Methods