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relative abundance

Posted by athompson314 on 29 Jan 2018 at 00:00 GMT

These are beautiful and very interesting images. However, I find it is a leap to conclude that relative abundance of sequenced cell sorts accurately represents the relative abundance from microscopy and can be used to conclude the identify of single cells observed by microscopy.

There are many reasons the sequence results from the sorts could diverge from the true relative abundance of the cells, including genome copy number, lysis efficiency, and amplification efficiency in the whole cell PCR. No lysis step was described and no mock communities were sorted and sequenced similarly as controls to make sure of the power of this method to quantify relative abundance.

The arrangement and numbers of cells observed by microscopy is more consistent with the prominent cell being UCYN-A rather than Prochlorococcus. Zehr has already commented on this point. But it cannot be concluded either way from the Kamennaya et al images without use of another method or better understanding of the SEM morphology of Prochlorococcus and UCYN-A.

I don't doubt that Braarudosphaera–like cells can prey upon Prochlorococcus. Our previous work showed grazing of Prochlorococcus by a Braarudosphaera like cell in 2008, which could explain the presence of Prochlorococcus co-sorting with the pigmented eukaryotes in addition to the presence of UCYN-A. http://onlinelibrary.wile...
However, this work showed that many other small eukaryotes also prey on Prochlorococcus, and the sequenced sorts of the Kamennaya et al paper suggest that other small eukaryotes were present in the sorts.

No competing interests declared.