Talk:Magnetotactic bacteria

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I have just started translating this article from the Italian (following a request from an english language wikipedian on the it.wiki Bar). The full working draft is here: User:Pippu d'angelo/Magnetotactic bacteria - please feel free to come along a lend a hand - I just thought I would leave a stub here until we had it finished because it could take a while and I don't know diddly squat about this stuff!! ρ¡ρρµ δ→θ∑ - (waarom? jus'b'coz!) 01:48, 11 December 2005 (UTC)

I just finished an article on Magnetosome which potentially duplicates some of the material here. The Italian article doesn't look very promising - it is too technical and messed-up. I will try to clean it if you don't mind. In the meantime here is some information which we may include when translation is finished. Lejean2000 10:29, 30 January 2006 (UTC)

The use of the magnetic field of Earth for orientation is known as magnetotaxis. Response to light (phototaxis) and chemical concentration (chemotaxis) exist in other species of bacteria. However, experiments involving various strains of magnetotactic bacteria have showed clearly that magnetotaxis and aerotaxis work in conjunction in the magnetotactic bacteria. Aerotaxis is the response by which bacteria migrate to an optimal oxygen concentration in an oxygen gradient. It has been shown that, in water droplets, one-way swimming magnetotactic bacteria can reverse their swimming direction and swim backwards under reducing conditions (less than optimal oxygen concentration), as opposed to oxic conditions (greater than optimal oxygen concentration). The behaviour that has been observed in these bacterial strains has been referred to as ‘magneto-aerotaxis’ (Blakemore et al, 1980). Two different magneto-aerotactic mechanisms — known as polar and axial — are found in different magnetotactic bacterial strains. Some strains that swim persistently in one direction along the magnetic field (NS or SS) — mainly the magnetotactic cocci — are polar magneto-aerotactic. Those that swim in either direction along magnetic field lines with frequent, spontaneous reversals of swimming direction without turning around — for example, freshwater spirilla — are axial magneto-aerotactic and the distinction between NS and SS does not apply to these bacteria. The magnetic field provides both an axis and a direction of motility for polar magneto-aerotactic bacteria, whereas it only provides an axis of motility for axial types of bacteria. In both cases, magnetotaxis increases the efficiency of aerotaxis in vertical concentration gradients by reducing a three-dimensional search to a single dimension.

It has been suggested (Chang and Kirschvink, 1989) that magnetotactic bacteria evolved in the early Proterozoic Era, as the increase in atmospheric oxygen reduced the quantity of dissolved iron in the oceans. Organisms began to store iron in some form, and this intracellular iron was later adapted to form magnetosomes for magnetotaxis. These early magnetotactic bacteria may have participated in the formation of the first eukaryotic cells. Biogenic magnetite not too different from that found in magnetotactic bacteria has been founded in higher organisms, from Euglenoid algae, to salmon, pigeons, and humans.

Chang, S., Kirschvink, J., 1989. Magnetofossils, the magnetization of sediments, and the evolution of magnetite biomineralization. Annural Reviews of Earth and Planetary Sciences 17, 169–195.

Blakemore, R. P., Frankel, R. B. & Kalmijn, A. J. Southseeking magnetotactic bacteria in the southern hemisphere. Nature 236, 384–385 (1980).

Lejean2000 10:29, 30 January 2006 (UTC)

  • Hi Lejean - please feel free to tackle this page any way you wish - I started the translation from Italian to English, and to be honest, most of it was way over my head - I don't have any great desire to come back to it any time too soon. Flag of Sicily.svg ρ¡ρρµ δ→θ∑ - (waarom? jus'b'coz!) 10:48, 30 January 2006 (UTC)

Latest edits[edit]

It's great that a native speaker of Italian has revisited this English translation, seemingly with a good grasp of the science (something I definitely lacked). But please be careful not to replace grammatical English sentences and phrases with ones that are clearly not grammatical. An example includes replacing "less favourable conditions" with "reducing conditions"; "deteriorating conditions" might be better - there are a few examples like that amongst some of the latest edits. I would like to help, but to be honest, I can't bring myself to look at this material again! ρ¡ρρµ δ→θ∑ - (waarom? jus'b'coz!) 12:15, 4 May 2006 (UTC)

I'm not sure, but I suspect "reducing" may actually be a techincal term - in redox it's the opposite of "oxidising". Andjam 13:17, 4 May 2006 (UTC)
Yes, Andjam guess is correct. With "reducing conditions" I meant to translate the term used in the italian article to describe those conditions suitable for a chemical reaction of "reduction". If you can point out the other "suspicious" sentences I'll check them out in order to be double sure I haven't done any erroneous translation.
BTW, I'll try to check out the rest of the article soon, it has been on my "To Do" list for quite some time now! :) Berserker79 13:56, 4 May 2006 (UTC)
Sorry - my apologies - I better steer clear of this one - I admitted from the start it's all way over my head! Absolutely none of it makes sense to me, so I'm not really in a position to offer pointers on any aspects of it. ρ¡ρρµ δ→θ∑ - (waarom? jus'b'coz!) 23:40, 4 May 2006 (UTC)
Don't worry, no need to apologize. Actually I think you've done a good job with the initial translation in spite you report not being much familiar with the article's topic. Fact is I have to agree with Lejean2000 when he says the original Italian article is too technical and cramped at times: I've fully read through it and agree some of its contents may cause a bit of confusion even if you have some specific knowledge on magnetotactic bacteria! I'll keep up on working on this English version and see if I can try to make it more accessible for everyone. Berserker79 12:25, 5 May 2006 (UTC)

References[edit]

The Bellini reference is extremely obscure; after a student in one of my classes cited Bellini as the discoverer of magnetotactic bacteria, I tracked it down and updated the introduction accordingly.

The references in this article are a mess; they should probably be updated to use the Wikipedia footnote/citation system.

I don't have time to update the main body of the article, but there are numerous places where the writing is obscure enough to be inaccurate. Bobkopp 16:11, 17 June 2006 (UTC)

Updated references to use the footnote/citation system. Berserker79 10:32, 19 June 2006 (UTC)

Recent news:[edit]

In WIRED, it was noted that there was a 16-year-old that used Magnetotacit bacteria to gerarate a current for a 48-hour stretch. I just felt it should be noted.

magnetotactic bacteria from mars???????????????[edit]

Some Scientists now believe that the microbacteria found on The meteroite that crash landed in Antartica are Magnetotactic bacteria. I think That I just should of Noted That For more info go to

http://mars.jpl.nasa.gov/newsroom/pressreleases/20020802a.html —The preceding unsigned comment was added by 67.82.242.174 (talkcontribs) .

Magnetic properties of magnetosomes contradicts itself in article[edit]

I noticed the article contradicts itself regarding the remanence of the magnetic field in the magnetosomes. In the last sentence of the first paragraph under the Magnetism heading, it says the magnetosomes are large enough to have a permanent magnetic field. However, under the Biotechnology Applications heading, it claims the particles are purely superparamagnetic and thus no remanent fields. I know enough to know that these statements contradict, but unfortunately I don't know the answer! My basic knowledge of magnetism tells me that the chain-like structures of the magnetosomes do preclude the necessity for the particles to have a remanent field, because the chain will align with an external field to minimize energy without remanence (and if the particles can hold remanence, it raises the question of whether this feature is used by the living organism and how they get aligned in the first place). My other understanding, however, is that there isn't an exact transition between superparamagnetic and not -- the remanence in these particles can in many cases exist, but just be very weak and in most practical cases still be called "superparamagnetic".

I think the article needs to be further checked for accuracy -- it's pretty dense and has a lot of details that may not be accurate. —The preceding unsigned comment was added by Femtoamy (talkcontribs) .

I don't know the answer either, but I put {{contradict}} on the article so hopefully someone will come along who does. —Keenan Pepper 01:31, 25 July 2006 (UTC)
I don't remember if I wrote this section, but the sentence saying that magnetosomes are large enough to have a permanent magnetic is not technically correct. Magnetosomes are large enough to have their own magnetic field but size has little to do with changes in polarity in this case. I fixed it. --Lejean2000 14:14, 25 July 2006 (UTC)
Magnetosome crystals are single domain, which means they are larger than superparamagnetic crystals. Bobkopp 03:52, 4 August 2006 (UTC)
Strictly speaking, not all magnetosome crystals are large enough to be single domain by themselves. Some need the chain to keep them aligned. RockMagnetist (talk) 15:39, 2 September 2010 (UTC)