MITOCHONDRIAL DNA IN THE OOGAMOCHLAMYS CLADE (CHLOROPHYCEAE): HIGH GC CONTENT AND UNIQUE GENOME ARCHITECTURE FOR...

Area of Science:

• * Molecular Biology
• * Evolutionary Biology
• * Phycology

Background:

• * Most green algal (Chlorophyta) mitochondrial genomes are circular and AT-rich.
• * The Reinhardtii clade exhibits linear, sometimes fragmented mitochondrial genomes with high GC content.

Purpose of the Study:

• * To investigate mitochondrial genome conformation and GC bias in the Oogamochlamys clade.
• * To determine if the Oogamochlamys clade shares genomic characteristics with the related Reinhardtii clade.

Main Methods:

• * Southern blot analyses using cob and cox1 probes on total DNA from Oogamochlamys and Lobochlamys taxa.
• * Sequence analysis of partial cob and cox1 genes.

Main Results:

• * Mitochondrial DNA in Oogamochlamys is linear and fragmented into multiple sizes with overlapping homology.
• * High GC content (49.9%-65.1%) was observed in partial cob and cox1 sequences.
• * Evidence of pseudogenes and truncated sequences in the mitochondrial genomes of Lobochlamys culleus.

Conclusions:

• * Linear, fragmenting mitochondrial DNA likely originated in an ancestor common to the Reinhardtii and Oogamochlamys clades or earlier in Chlorophyceae evolution.
• * The Oogamochlamys clade shares derived mitochondrial genome features with the Reinhardtii clade.