Abstracts

Genetic Bases of Biodiversity

More than 10 chloroplast genomes are completely sequenced so far what allows analyze them comparatively using informational technologies. In this report we scrutinized the nucleotide composition of chloroplast genomes and their functional regions from 15 species. It was revealed that despite of substantial heterogeneity in nucleotide composition (fA,fT,fG,fC) of DNA there is a limitation on relative variability of nucleotide frequencies in single strand of chloroplast DNA which was called by us as “four-nucleotide-rule” (FNR) - difference between the complementary nucleotide ratios are proportional to purine content (fR): fA/fT – fC/fG = a(fR-0,5) + b, where а and b – linear regression parameters. For W-strand of chloroplast DNA the regression parameters are as follows:

Species	DNA, nucleotides	Regression	r± Sr
Arabidopsis thaliana Cyanophora paradoxa Chlorella vulgaris Euglena gracilis Epifagus virginiana Marchantia polymorpha Mesostigma viride Nicotiana tabacum Oryza sativum Odontella sinensis Porphyra purpurea Pinus thunbergiana Spinacia oleracea Toxoplasma gondii Zea mays	154478 135599 150613 143172 70028 121024 118360 155939 134525 119704 191028 119707 150725 34944 140387	дельта=7,45(fR-0,5)-0,008 дельта=7,81(fR-0,5)-0,026 дельта=6,97(fR-0,5)-0,003 дельта=2,59(fR-0,5)-0,112 дельта=7,83(fR-0,5)-0,001 дельта=6,76(fR-0,5)+0,001 дельта=8,21(fR-0,5)-0,021 дельта=7,53(fR-0,5)-0,007 дельта=7,63(fR-0,5)-0,002 дельта=8,39(fR-0,5)-0,013 дельта=8,22(fR-0,5)-0,003 дельта=8,05(fR-0,5)-0,005 дельта=7,57(fR-0,5)-0,001 дельта=9,52(fR-0,5)-0,034 дельта=7,79(fR-0,5)-0,002	0,968± 0,036 0,946± 0,049 0,968± 0,036 0,354± 0,422 0,980± 0,043 0,895± 0,072 0,906± 0,070 0,964± 0,038 0,983± 0,028 0,984± 0,029 0,982± 0,024 0,987± 0,027 0,968± 0,036 0,957± 0,097 0,985± 0,026

where Δ= fA/fT – fC/fG, а r-Sr correlation coefficient with standard error. The difference of E.gracilis chloroplast genome properties from the others is determined by the probable recombination occurred somewhere within the 70000 nucleotides from the first nucleotide (according to GenBank entry numbering). Thus if one connects W-strand of DNA before this point with the C-strand after that, FNR describes by the regression: Δ=5,05(fR-0,5)+0,196, r-Sr=0,925-0,058. The analysis of the protein coding genes, tRNA and rRNA genes, introns and intergenic spacers from the chloroplast genomes studied, showed good correspondence of their nucleotide composition to the FNR.

Note. Abstracts are published in author's edition

|Home Page| |English Part|

Go to Home