It's possible that only one reader will care about this. But this is one minor detail that I came across while researching yesterday's post.
Komokiacea are large deep-sea branching protists that are expected, but not conclusively demonstrated, to belong or be related to Foraminifera. Attempts to extract molecular data for komokiaceans have, to date, failed miserably (Lecroq et al., 2009). Or have they?
In a paper written by Gooday et al. (1997), my attention was caught by the offhand comment: "We include Rhizammina algaeformis Brady 1879 [another deep-sea branching foram] within the Komokiacea on the basis of its 'softpart' organization". This relationship, it turns out, had originally been proposed by Cartwright et al. (1989). If this assignment is correct then komokiaceans have been appearing in molecular phylogenies for some years and nobody has been paying a blind bit of notice! Even more interestingly, Pawlowski et al. (2003) placed Rhizammina as sister to the xenophyophore Syringammina. Xenophyophores resemble komokiaceans both in being large branchers and in the sequestration of stercomata (faecal pellets) within their structure. A close relationship between the two groups would be quite credible. However, no other authors to date appear to have commented on Cartwright et al.'s reclassification of Rhizammina so I have no idea whether it's regarded as credible.
Discuss.
REFERENCES
Cartwright, N. G., A. J. Gooday & A. R. Jones. 1989. The morphology, internal organization, and taxonomic position of Rhizammina algaeformis Brady, a large, agglutinated, deep-sea foraminifer. Journal of Foraminiferal Research 19 (2): 115-125.
Gooday, A. J., R. Shires & A. R. Jones. 1997. Large, deep-sea agglutinated Foraminifera; two differing kinds of organization and their possible ecological significance. Journal of Foraminiferal Research 27 (4): 278-291.
Lecroq, B., A. J. Gooday, T. Cedhagen, A. Sabbatini & J. Pawlowski. 2009. Molecular analyses reveal high levels of eukaryotic richness associated with enigmatic deep-sea protists (Komokiacea). Marine Biodiversity 39: 45-55.
Pawlowski, J., M. Holzmann, J. Fahrni & S. L. Richardson. 2003. Small subunit ribosomal DNA suggests that the xenophyophorean Syringammina corbicula is a foraminiferan. Journal of Eukaryotic Microbiology 50: 483-487.
_(cropped).jpg)
3 weeks ago in Genomics, Medicine, and Pseudoscience
Ok, your question is beginning to seriously nag me in my sleep. Almost as badly as the idea of a possible size/morphological dimorphism in centrohelid heliozoans (environmental microbiologists, by which we mean bacteriologists, are rumoured to have some interesting data on that...).
ReplyDeleteI've been told that the absense of Komokians from Foraminifera is due to no living specimen ever having been recovered yet, and thus we do not know whether they have the characteristic "granuloreticulosean" pseudopodia. However, phylogeny should ideally help resolve that a bit even in the absense of their cell biology, even if only tentatively. I wouldn't rely entirely on molecular data, but it often gives a reasonably good idea.
I'll look into the literature with your question in mind... perhaps there's something left unanalysed in *gasp* protistological literature!
If I add in a sentence in the foram chapter about Komokians potentially being -within- Foraminifera as shown by Rhizammina etc, how should I credit you for pointing that out? =D
All I ask is that you tell your many friends about me and, if they aren't already reading this site, demand to know why?
ReplyDeleteLOL I've already told several people; one of the authors of the Chromera paper you blogged on earlier approves of you and your blog, btw =D (and you got the facts straight).
ReplyDeleteMany of them don't read blogs, period. Apparently "too busy". Part of the problem is that many have yet to discover RSS feed, which is there specifically to keep track of site updates without putting any effort into it...
I just read the 1989 Rhizammina paper in question; the description sounds awfully Xenophyophoric to me. I'm entirely not convinced it's a Komokian rather than a Xeno. In fact, it even branches with Xenos in Lecroq et al. 2009. I vaguely recall at least some Komokians having septate cytoplasm (see fig 3b inGooday et al. 2007 Zool J Linn Soc (http://dx.doi.org/10.1016/j.dsr2.2007.07.003)), which neither Xenos nor Rhizammina seem to have. I am now gonna try to see if septa are a normal komokian thing.
In fact, I am currently entirely confused what's the difference between Komokians and Xenophyophores. In any case, Rhizammina appears to be a Xeno, esp. considering the stercomata, coenocytic highly invaginated protoplasm, and the overall cellular organisation (and size closer to Xenos; they even mentioned it would be the largest Komokian known if it were one...)
Maybe it's time to go bug "my" foram expert =D
The amount of research that can go into a single sentence of a chapter (or a blog post) is utterly insane. No wonder popular (and even 'unpopular') science writing is generally low-quality...
I am currently entirely confused what's the difference between Komokians and Xenophyophores.
ReplyDeleteI have to say, the same question has been bugging me. The only komoki paper I've looked through with any real attention is the original 1977 one by Tendal and...erm...some other guy and that didn't really seem much more definite about why komoki weren't xenophyophores than "because Øle Tendal says they're not".
Do komoki sequester barite the way that xenophyophores do? Also, while xenophyophore tubes are generally anastomosing, I believe that anastomosing tubes are a rarity among komokiaceans.
Oh, and while you're at it, is there any credibility to the identification of Pelosina as a psamminid?
ReplyDeleteThis comment has been removed by a blog administrator.
ReplyDeleteArgh, sorry for multi-post. Kept giving me "requested URL too large" error; wtf?
ReplyDeleteHi Chris. I think we're both doing the same thing...
ReplyDeleteI took the liberty of removing the redundant comments. Sorry about that.
ReplyDeleteThe 'polyphyletic Komokiacea' paper you're thinking of is probably the Lecroq et al. (2009) one I linked to above. The authors don't really believe that their results are valid; rather, they're reporting that their attempts to extract sequence data from komoki have produced a hell of a lot of contamination and there's no way to tell which (if any) of the results are true komokiacean sequences.
Psi Wavefunction:
ReplyDelete"Thus far, everyone seems to just assume Komokians aren't Xenos, and reference Tendal & Hessler '77... where the only line about Xenos goes like this:
"Hessler (1974) and Hessler & Jumars (1974) have suggested that they may belong to the Xenophyophoria, but Tendal rejects this possibility." (T&H 1977:166)
It seems like the authors disagree with each other (note: Hessler is second author of this paper, and also the author of the xeno idea), and didn't want to discuss the topic further. But they should at least pretend to give some explanation why Tendal rejects their xeno association.
Perhaps part of the problem is that Xenos weren't considered to be forams at the time (based on stercomata and 'lack' of sexual phase (AWFUL, HORRIBLE character...), from what I gather); for some reason, it was generally assumed that Komokians are forams, and thus cannot be Xenophyophores. Note that Komokians too have stercomata, and 'lack' known sexual phases. How that makes any sense is beyond me, but seriously, this entire taxonomic mindfuck is in desperate need of love and attention, both from cell/organismal biologists and phylogeneticists.
Thus, my understanding of the story thus far: Komokians aren't Xenos because Tendal said so in 1977.
ARRRRRGGGGGHHHHHHHH.
Gonna check the recent phylogeny paper in closer detail; saw a couple trees somewhere that had the poor komokians POLYPHYLETIC, strewn all over the foram tree. WTF.
Someone's asking some foram experts for me, so maybe we should just wait for a reply. There's a conference on right now, but maybe next week it's time to resolve this by emailing people who might know. Or know that no one knows, anyway.
I'll look at Pelosina after I get the higher-level stuff sorted a bit ;-)
PS: Keeps giving me "URL too large to process" error; WTF?
Thanks Edward. My comment above is in reply to the accidentally deleted comment of Psi's that Edward has restored.
ReplyDeleteSorry about the mess, will refrain from obsessive-compulsive resubmission next time >_>
ReplyDeleteHere's where I saw another fishy phylogeny:
http://www.cushmanfoundation.com/awards/students/sabbatini.pdf
Has pretty pictures towards the end though.
We have a few guys here who are more or less high masters of phylogenetic arts, I could ask them for an opinion. Do suspect serious contamination though, considering Komokians and Xenophyophores (or "Komokian and regular Xenophyophores" =P) like to cover themselves in other forams...
Y'know, things would be so much easier if more than like 5 people in the entire world knew of these things...