Variation in nuclear DNA base composition (mol % G + C) in three orders of marine green algae

Abstract

Estimates of nuclear DNA base pair composition by determination of thermal denaturation temperatures (Tm ) indicated guanine + cytosine (G + C) levels of 35-56% for 17 species of marine green algae . Tm values were found to be reproducible with coefficients of variation among samples and replicates of generally less than 1 percent . G + C % values in four species of Enteromorpha varied within a narrow range of 53-56%, whereas values for three species of Ulva showed substantially greater variation, ranging from 35-55% . Ulva fasciata collections from two geographically separate North Carolina sites had mean G + C composition of 44 .8 and 35 .6 respectively, suggesting that these populations may be genetically distinct. Enteromorpha linza, which has been treated as a species of Ulva, had a G + C composition of 53 .2, typical of the Enteromorpha species investigated . Nuclear DNA base pair composition data for species of Cladophorales and Caulerpales are given as well .

The Amplification and Application of Ribosomal RNA (rDNA) Gene Sequences of <i>Blidingia minima</i> (Chlorophyta, Blidingia)

“…rDNA genes. The total GC content of the ribosomal RNA gene was 54.26%, which was in the range of 35% -56% [19]. Given their high evolutionary rate, ITS sequences are expected to be suitable for detecting interspecific variation [20] [21].…”