Talk:Diatom

Genome

user:Petaholmes added this material to the article:

The full genome sequence of saltwater diatom Thalassiosira pseudonana shows that diatoms have a complex evolutionary histroy. Like other early microbes, diatoms seem to have acquired new genes by engulfing microbial neighbors. Perhaps the most significant acquisition was an algal cell, which provided the diatom with photosynthetic machinery. As a result diatoms are left with what appears to be a mix of plant and animal DNA.

Reference: Armbrust el al. (2004). The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution, and Metabolism. Science 306:79-86

Has anyone read this article? Saying they have a mix of plant and animal DNA does not make much sense, since neither diatoms nor their chloroplasts developed from animals, and probably means algae and protozoa. However, the idea that diatoms have a complex evolutionary history including an engulfed algal cell is already well-known, and is something that applies to heterokonts in general so does not really belong here. I've removed this until someone can check the journal, but it looks like this is simply reaffirming the established phylogeny.

The paper says that about a half of diatom proteins have closest homology to plant, red algal and animal (they used mouse sequence data). Genes that were homologous to animal genes had no homology to plant or algal proteins. The paper proposes that animal-like genes may have come from a secondary host, but cannot really say --nixie 23:32, 2 Oct 2004 (UTC)

2 comments

A: The last section was taken from some aincent book, is that OK, or should it be checked, or should the notice be removed?

B: Supposedly they're really nice looking in a microscope, anyone have a pic?

Thanx 68.39.174.150 21:15, 28 Apr 2005 (UTC)

Yup, looks like an old textbook

Yup, I think it's still mostly from a "classic" textbook. Certainly it's big on traditional observational biology. I've not erased it yet, but might get around to this as I gradually change the text paragraph by paragraph.

Agree about the pictures. There are plenty on the web, but we need someone who owns some pictures to put them on.

Here are some pics from the NOAA, Image:Deepwater organic remains from Antartic waters 5-6000m deep.jpg is a historical drawing, and this Image:Diatoms through the microscope.jpg is a photo. Both are good and could both go in the article--nixie 23:07, 28 Apr 2005 (UTC)

Phytoplankton

Whoa—that's a really dense article! How about explain it in terms a layman can understand? How in hell can one write such a long article without ever mentioning phytoplankton?? And how about some external links? For instance, NASA's SeaWIFS? Lupo 07:06, 13 Jun 2005 (UTC)

BTW, SeaWIFS could use some expansion... :-) Lupo 07:06, 13 Jun 2005 (UTC)

OK, point taken. The article could definitely do with some expansion to point readers to more general items on phytoplankton, etc. My fault as I'm responsible for most of the text. That said, I don't think it needs anything on SeaWIFS - that's definitely something for the phytoplankton page (or, better still, the chlorophyll page). SeaWIFS doesn't say anything specific about diatoms, but allows us to infer information about phytoplankton generally. Anyway, I'll try to edit the article over the next few days, but (obviously) have a go yourself if you fancy it. --Plumbago 09:28, 13 Jun 2005 (UTC)

The problem is, I lack the knowledge to do this. I'm no marine biologist! And just to make sure I'm not misunderstood: I'm not asking to dumb the article down. But I think some introductory paragraphs giving the wider picture might help. (BTW, I just happened to stumble upon the article because I have recently read Gregory Benford's Timescape again—that gives you a pretty good idea about my knowledge on diatom! :-) Lupo 10:56, 13 Jun 2005 (UTC)

I think the text was generally good, but I've tried shuffling it so that information on what diatoms are is near the top, and details of how they work is lower down. I've also added some notes on classification. Please take a look and make sure the changes are satisfactory. Josh

Good job Josh. I've made some minor edits to your changes, but I like what you did with the page. You don't, by any chance, have any pictures of diatoms? It's the one major omission on the page (especially since it says how beautiful they are), but I've not got any (legitimate) pictures I could put on. --Plumbago 08:25, 14 Jun 2005 (UTC)

Yup, much better already. What's wrong with the image mentioned above? And is the EO DAAC Study: Polynyas, CO2, and Diatoms in the Southern Ocean a link worth adding to the article? Lupo 13:01, 14 Jun 2005 (UTC)

Thanks! I've added the photo nixie mentioned. The sketch could be useful, too, if the identifications in it are still accurate; but note Dictyocha is not a diatom. I don't have any worthwhile pictures myself - very few of my photos are plankton. I'll let you decide about the link. Josh

That's a nice one! Good choice. I think most (if not all) of the algae one can make out are diatoms. Certainly look that way. --Plumbago 08:46, 15 Jun 2005 (UTC)

Classification

At the moment in the text we say that the heterokonts may be classified as a division (phylum) or as a kingdom. I might be mistaken, but is the kingdom referred to here Chromista? I've already put a reference to this in the main article. However, looking again at the Chromista article, it seems to suggest that the heterokonts are a sub-division rather than a kingdom (e.g. several other major groups are bundled into the Chromista - it's not a heterokont-only party). Could anyone clarify? --Plumbago 11:42, 21 Jun 2005 (UTC)

The heterokonts can be classified as a phylum, kingdom, or something in-between - I'll make the last explicit in the article. As an example, Cavalier-Smith (the main proponent of the Chromista) places the diatoms as follows:

Kingdom Chromista
Subkingdom Chromobionta
Infrakingdom Heterokonta
Superphylum Gyrista
Phylum Ochrophyta
Subphylum Diatomeae

However, other classifications tend to be somewhat different from his. Not everyone accepts the Chromista, and either leave the heterokonts among the Protista or give them their own kingdom (e.g. Heterokonta or Stramenopila). The short story is that the situation is still messy, and not particularly relevant, but I thought a brief note was needed to explain how diatoms could be divided into classes yet listed as a class themselves. If you can make things more transparent, please do. Josh

Thanks for explaining this. I've not a clue about classification at this level. Until earlier today, I'd never heard of the Chromista, so I'm more than happy to leave the whole classification section to you. Keep up the good work! --Plumbago 16:09, 21 Jun 2005 (UTC)

Another question about classification: I was talking to a grad student doing diatom taxonomy this evening, and she (and her advisors) seem pretty certain that diatoms are plants. I don't have a copy of The Diatoms to see what it says, but they still seem protistan to me. - 24 Oct 2006 —The preceding unsigned comment was added by 68.162.84.17 (talk • contribs) .

Your grad student friend may just have been using the word "plant" in the broad sense of autotroph rather than to specifically indicate the evolutionary branch the diatoms belong to. It's clear that they're not Kingdom Plantae just from their photosynthetic machinery - their chloroplasts have a greater number of cell membranes surrounding them indicating an evolutionary pathway distinct from plants (see here). That said, the classification scheme used here (kingdom protista and division heterokontophyta) is not the only one, and it may just be that your friend is being taught by someone who prefers an earlier scheme. Cheers, --Plumbago 08:11, 25 October 2006 (UTC)

Nanotech

The following was inserted into the "Evolutionary History" section :

In 2005, a team from Georgia Tech, led by Chemical engineer Kenneth Sandhage, has published details of a new process for converting the finely-detailed silica skeletons of diatom into synthetic replicas of materials such as titanium dioxide which conduct electricity and could be used in electronic devices. This development could lead to the genetic modification of diatoms for creation of nano-materials.

I've removed it for now as it clearly doesn't belong in this section (though could be put in an "Applications" section), and doesn't make complete sense. What does it mean to be a "synthetic replica" of titanium dioxide? Is "substitute for" titanium dioxide meant instead? I've no idea, so have removed text to here. Of course, I could just be being stupid ... --Plumbago 17:02, 4 October 2005 (UTC)

P.S. If this has been published, the reference would be good too.

Also there are some early references that Diatom can be used for paint ( http://www.wired.com/science/planetearth/news/2007/10/eco_textiles )

The "synthetic replica" bit definitely sounds odd. It's either titanium dioxide or it isn't. Still, with a rewrite and some better citations, I'm sure it could be a very good addition to the article. 205.175.225.22 (talk) 19:44, 2 January 2008 (UTC)

They start with a natural diatom, and then replicate the shape of the silica shell exactly except using more 'useful' materials. So you end up with something that has the exact shape of the original diatom but is made of arbitrary materials instead of silica. This much was published in Nature. combine this with genetic engineering to modify the structure of the original diaton, and you can end up with very interesting structures made of very useful materials. —Preceding unsigned comment added by 190.22.97.173 (talk) 00:37, 26 June 2008 (UTC)

Food

What is the diatom food? —Preceding unsigned comment added by 200.73.30.108 (talk) 12:58, 11 October 2007 (UTC)

Diatoms are photosynthetic organisms...in fact some of the most abundant types!

Aren't they made out of glass?

According to this website, they are.

Lunakeet 17:26, 21 May 2008 (UTC)

Well, apparently silicon dioxide (silica) is a component of glass.

Lunakeet 17:28, 21 May 2008 (UTC)

Number of species

There is a large discrepancy between the number of species in the Diatom article (100 000) and the Heterokonta article (10500), the diatoms are after all a class in phylum heterokonta. The heterokonta is lacking a good reference, but there is not much certainty around the number of diatom species either. Number of diatom species described in articles largely depends on what authors base their guess upon (and species concept), and they are wildly different, ranging from a few thousand species, via 10 000 species suggested by Guillard an Kilham (1977) up to the approximately 200 000 species suggested by D.G. Mann (2004?) at Royal Botanical Garden in Edingurgh, Scottland. So what do we do? At least we should inform about the uncertaity regarding number of species? Rex shock (talk) 11:51, 30 June 2008 (UTC)

Along these same lines, how many diatoms are actually identified, named, classified, etc.? Estimators are professional biologists (?), not professional statisticians, not professional information scientists? At any rate, what is the purpose of the estimates, because certainly estimates have them. Are they to encourage research funding? To estimate biodiversity? Or are they for a purpose as limited, say, as creating factoids for PBS specials? 24.130.17.190 (talk) 09:24, 5 December 2008 (UTC)

Calcareous Diatoms?

This article completely ignores the fact that many diatoms secrete shells of calcium carbonate, which is the primary source of calcareous diatom oozes.Cadwallader (talk) —Preceding undated comment was added at 20:28, 1 February 2009 (UTC).

Have you a reference for that? Did my Ph.D studying lacustrine diatoms and have never found reference to calcium carbonate species, are you sure your not thinking of foraminifera or radiolarians which can be in the same water column as diatoms and drop out to form a diatom rich calcareous ooze - i.e carbonate substrate with silicious diatoms in it. Munse (talk) 12:20, 5 February 2009 (UTC)

I'm with Munse. I'm not aware of any calcareous diatoms. Their use of silica is pretty much a defining feature of the group as I understand it. There are plenty of other phytoplankton and zooplankton that use calcium carbonate, and I can only assume that it's these that are being referred to here, possibly in the manner that Munse suggests. Cheers, --PLUMBAGO 14:12, 5 February 2009 (UTC)

Euk x Prok

'Eukaryotic' algae? Is there any other kind of algae?? --Spmoura (talk) 23:47, 17 May 2010 (UTC)

The term "algae" has also been applied historically to some prokaryotic phototrophs, with the most well-known example being blue-green algae. Technically, the term "algae" is now generally understood to preclude bacteria as well as "higher plants", but the terminology is still sometimes used. One of the remaining problems with the term "algae" is that the eukaryotic groups that fall under it have quite a diverse evolutionary history, so it's debatable whether the term is much use at all. Anyway, I'll alter the use here. Cheers, --PLUMBAGO 16:34, 21 May 2010 (UTC)

Algae or not

The first sentence in the article says diatoms are a major group of algae. The second sentence under 'Aquariums' says they are not algae at all.97.113.84.178 (talk) 14:12, 22 September 2010 (UTC)

The anomalous edits were by a single editor, and introduced other (unsourced) material of questionable quality (cf. "carbon nutrients"). I've rolled back to remove all of this. --PLUMBAGO 14:39, 22 September 2010 (UTC)

Name

Why are they called Diatoms? When I was younger, I thought that was weird because it implied that they were made of only two atoms, which is obviously not the case. Stonemason89 (talk) 04:35, 5 December 2010 (UTC)

It's from the Greek, it means "cut in two" (on-line etymology dictionary), probably because of the two overlapping valves. There's also a company that makes diamond knives for slicing biological tissue (and other things) into sections less than 100nm thick. The company is called "Diatome," and the name is from the same origins. --Kleopatra (talk) 05:09, 5 December 2010 (UTC)

Nano Silica based micro nutrients

We have invented a Nano Silica based micro nutrient powder specifically to grow diatoms. US Patent No. 7585898, Sept 9, 2009. Title "A Composition for growth of Diatom Algae." This used Nano silica to deliver micro nutrients to Diatoms in any type of water.

I had incerted a reference to this invention on the Diatom page but this was deleted, can anyone review the patent and include a suitable reference. --Bhaskarmv (talk) 06:54, 23 January 2011 (UTC)

— Preceding unsigned comment added by Bhaskarmv (talk • contribs) 05:49, 23 January 2011 (UTC) 

It might be helpful if you first explained why this powder is special. Diatoms are not especially difficult to culture using fairly standard laboratory chemicals (I've cultured some myself), so it's unclear what's significant about the powder that you mention. Leaving aside the patent itself, have any scientific publications appeared concerning the diatom growth properties of this powder? They might clarify the use and importance of the powder greatly. --PLUMBAGO 16:26, 23 January 2011 (UTC)