I am very exciting to see that the authors have connected the excess of introns in highly expressed Ostreococcus genes to the lower number of nuclear pores per nucleus. Although this takes only a few sentenses in their discussion, it is really an advance. It is much more reasonable than the assumption that introns may have undiscovered regulatory elements that may promote the expression of their host genes. As I see, this is a very hopeful explanation for the retention of introns in highly expressed genes in plants and microorganisms.

However, the explanation for longer intron length in highly expressed genes is not so satisfactory. Splicing is enough for the attachment of export-related proteins to mRNA, I do not know any evidence for the necessity of longer length. And it is the same case for NMD. I am looking forwards to more detailed discussion on intron length if the authors know some related references.

Deng-Ke Niu
College of Life Sciences
Beijing Normal University
Beijing, 100875
P. R. China
http://cmb.bnu.edu.cn/tea...
dkniu@bnu.edu.cn, dengkeniu@hotmail.com, dengkeniu@sina.com