| Summary: | 碩士 === 國立清華大學 === 輻射生物研究所 === 81 === Mitochondrial DNA (mtDNA) is an extremely usefu l molecule in
assessing relationships among species and populations that
diverged rather recently sin ceit has a higher evolutionary
rate than that of nu clear DNA. Sequence analysis of vertebrate
mtDNAs h as revealed that the displacement loop (D-loop) re
gion is the most rapidly evolving part of genome, w hile the
ribosomal RNA genes are quite conservative . These DNA
fragments are known to adjacent to eac h other inall the
vertebrate mtDNA examined. Howeve r, it has recently been
reported thatthe ribosomal RNA genes from Pekin duck is located
9.5 kb down s tream of D-loop.In order to understandthe
discrepa ncy in the gene locations, we cloned and sequenced the
mtDNA fragments containing D-loop region and ad jacent segment
from two different genera of ducks (Cairina and Anas). By
nucleotide sequence determin ations and homologous comparisons
with chicken mtDNA quence, we demonstrated that the D-loop and
ribosomal RNA genes are adjacent to each other in mitochondria
chondria of these two avians. A novel gene order(N D6-tRNAGlu-D-
loop) which conserved among the galli form birds also exists in
these two avians. Phylogen etic analysis of these two genera of
ducks, showed that the duck and chicken are come from a common
a ncestor. From the result of avians mtDNA polymearase chain
reaction (PCR) amplication, indicated that the avians which are
taxis to the same species, alt hough their morphology are very
different, may have the same or very similar mtDNA sequence.
Thus, mt DNA is apowerful tool in phylogenesis analysis of
related animals.
|
|---|
