"Genomes with high guanine-cytosine content can be difficult to sequence and knowing the guanine-cytosine content can help to assess the amount of resources needed for genome sequencing," Devarenne said.
The team determined B. braunii's genome size to be 166.2 2.2 million base pairs, Devarenne said. The size of the human genome is about 3.1 billion base pairs. That of the house mouse is also about 3 billion base pairs. But the B. braunii genome size is larger than any of the other six previously sequenced green algae genomes.
The team also looked at the phylogenetic placement of B. braunii where it belongs in the family tree of similar algae species. Though they knew from the work of other scientists that the B race of B. braunii was distinct from other races of B. braunii, there was some question that the genetic samples of the B race used in a previous study by other scientists might be contaminated by another algal species.
To check this, they used a process called reverse transcription to isolate genes from a pure culture of the B race of B. braunii, and then mapped those genes to confirm the relationship of the B race to other races of B. braunii.
"Our results support the original Berkeley DNA sequence used for phylogenetic placement was from a contaminating algae," Devarenne said. "And our study places the B race of B. braunii in the correct location on the 'algal family tree'."
The actual genome sequencing and mapping will be performed by DOE's Joint Genome Institute.
"We've submitted genomic DNA from B. braunii for JGI to use in sequencing, but that hasn't begun yet," he said.
|Contact: Robert Burns|
Texas A&M AgriLife Communications