Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein...Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein-coding, 2 ribosomal and 22 transfer RNA genes. The mt genome of Gekko is similar to most of the vertebrates in gene components, order, orientation, tRNA structures, low percentage of guanine and high percentage of thymine, and skews of base GC and AT. Base A was preferred at third codon positions for protein genes is similar to amphibians and fishes rather than amnion vertebrates. The standard stop codes (TAA) present only in three protein genes, less than those of most vertebrates. Transfer RNA genes range in length from 63 to 76 nt, their planar structure present characteristic clover leaf, except for tRNA-Cys and tRNA-Ser (AGY) because of lacking the D arm.展开更多
Brine shrimps,Artemia(Crustacea,Anostraca),inhabit hypersaline environments and have a broad geographical distribution from sea level to high plateaus.Artemia therefore possess significant genetic diversity,which give...Brine shrimps,Artemia(Crustacea,Anostraca),inhabit hypersaline environments and have a broad geographical distribution from sea level to high plateaus.Artemia therefore possess significant genetic diversity,which gives them their outstanding adaptability.To understand this remarkable plasticity,we sequenced the mitochondrial genomes of two Artemia tibetiana isolates from the Tibetan Plateau in China and one Artemia urmiana isolate from Lake Urmia in Iran and compared them with the genome of a low-altitude Artemia,A.franciscana.We compared the ratio of the rate of nonsynonymous(Ka) and synonymous(Ks) substitutions(Ka/Ks ratio) in the mitochondrial protein-coding gene sequences and found that atp8 had the highest Ka/Ks ratios in comparisons of A.franciscana with either A.tibetiana or A.urmiana and that atp6 had the highest Ka/Ks ratio between A.tibetiana and A.urmiana.Atp6 may have experienced strong selective pressure for high-altitude adaptation because although A.tibetiana and A.urmiana are closely related they live at different altitudes.We identified two extended termination-associated sequences and three conserved sequence blocks in the D-loop region of the mitochondrial genomes.We propose that sequence variations in the D-loop region and in the subunits of the respiratory chain complexes independently or collectively contribute to the adaptation of Artemia to different altitudes.展开更多
文摘Long-PCR amplification, clone and primer-walking sequencing methods were employed in determine the complete sequence of mitochondrial genome of tokay (Gekko gecko). The genome is 16 435 bp in size, contains 13 protein-coding, 2 ribosomal and 22 transfer RNA genes. The mt genome of Gekko is similar to most of the vertebrates in gene components, order, orientation, tRNA structures, low percentage of guanine and high percentage of thymine, and skews of base GC and AT. Base A was preferred at third codon positions for protein genes is similar to amphibians and fishes rather than amnion vertebrates. The standard stop codes (TAA) present only in three protein genes, less than those of most vertebrates. Transfer RNA genes range in length from 63 to 76 nt, their planar structure present characteristic clover leaf, except for tRNA-Cys and tRNA-Ser (AGY) because of lacking the D arm.
基金supported by the National Natural Science Foundation of China(30221004)to Wang WeiWeithe National Basic Research Program from Ministry of Science and Technology of China(2011CB944100)to Yu Jun
文摘Brine shrimps,Artemia(Crustacea,Anostraca),inhabit hypersaline environments and have a broad geographical distribution from sea level to high plateaus.Artemia therefore possess significant genetic diversity,which gives them their outstanding adaptability.To understand this remarkable plasticity,we sequenced the mitochondrial genomes of two Artemia tibetiana isolates from the Tibetan Plateau in China and one Artemia urmiana isolate from Lake Urmia in Iran and compared them with the genome of a low-altitude Artemia,A.franciscana.We compared the ratio of the rate of nonsynonymous(Ka) and synonymous(Ks) substitutions(Ka/Ks ratio) in the mitochondrial protein-coding gene sequences and found that atp8 had the highest Ka/Ks ratios in comparisons of A.franciscana with either A.tibetiana or A.urmiana and that atp6 had the highest Ka/Ks ratio between A.tibetiana and A.urmiana.Atp6 may have experienced strong selective pressure for high-altitude adaptation because although A.tibetiana and A.urmiana are closely related they live at different altitudes.We identified two extended termination-associated sequences and three conserved sequence blocks in the D-loop region of the mitochondrial genomes.We propose that sequence variations in the D-loop region and in the subunits of the respiratory chain complexes independently or collectively contribute to the adaptation of Artemia to different altitudes.
