Talmudic Question #34

We may be revealing our ignorance, but we are under the impression that although there are giant bacteria, there are no giant archaea. If this is the case, why might this be so?

Comments

[Carsten]

Dear Elio, I was just referring to your reply to Mike's comment. Sorry for causing confusion!

[elio]

Carsten,

Please enlighten me. The giants with vacuoles (T. namibiensis is what you're thinking of, right?) are Bacteria, but the question was about Archaea. Are there giant vacuolated Archaea?

Elio

[Carsten]

Why not count the little fellows with giant vacuoles, too? The contents of a vacuole might be less complex than the cytoplasma, but its sheer size should pose serious challenges for intracellular signalling and transport (energy, metabolites). Or shouldn't it? How do you wave to somebody who is beyond the horizon?

[Andrew Staroscik]

Forgive me for what may be a naive question, but if you leave out the ones with large vacuoles like T. namibiensis, how many giant bacteria are there? The Epulopiscium sp. and what else?

Andrew,
A good Talmudic question needs to be answered with another question. You make a great point. Some cyanobacteria that are fairly thick in diameter but don't qualify as giant, Anybody out there knows the answer?
Elio

[Autumn Cochrane]

Now, what constitutes a giant Archaea? Also, may be the reason why we haven't found a giant Archaea is because they are too primitive (Aren't they considered the precursors of bacteria?). If I'm completely wrong, let the record show that it's because I'm in the middle of taking my first Microbiology class!

Autumn,
You must be acing the course, at least as judged by the keen questions and answers you have sent us. On this one, "primitive" is a fighting word. People still argue about the earliest branching of life.

[Jonathan Badger]

Because the guys at wwww.giantmicrobes.com haven't seen the demand for a plush Methanococcus yet?

Jonathan,
Another example of how Archaea get dissed.

Elio

[Mike Gray]

How large does a cell have to be to be "giant"? Haloquadratum walsbyi ("Walsby's square archaeon") apparently runs up to 40 X 40 µm (no more than 0.5 µm thick, though) (Bolhuis et al. 2004 Environ Micro 6(12):1287).

Mike,
Glad to hear about the large size of H. walsbyi (a fascinating bug). We had volume in mind, in which case it wouldn't really qualify, but nice try! By our criterion, the bacterium Thomargarita namibiensis wouldn't qualify either. What;s giant there is the vacuole.
Elio

[qetzal]

I have no idea, but it's an interesting question. I hope someone offers a reasonable answer.

I hope you'll forgive me if I pose a vaguely similar question. Why are essentially all complex multicellular organisms eukaryotes?

I can imagine a few possible answers, but I wonder if there's any scientific consensus. I've tried searching PubMed, but haven't found much that's relevant.

Qetzal,
Great question, somewhat Talmudic itself. (Talmudists are said to often answer a question with a question). Maybe we should post it some time later and see what responses it elicits.
Elio