Re: Life: Turn it upside down!

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Sujet : Re: Life: Turn it upside down!
De : {$to$} (at) *nospam* meden.demon.co.uk (Ernest Major)
Groupes : talk.origins
Date : 16. Apr 2024, 20:25:30
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Organisation : A noiseless patient Spider
Message-ID : <uvmjb9$13tfh$1@dont-email.me>
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On 14/04/2024 18:50, Ernest Major wrote:
On 13/04/2024 15:11, Arkalen wrote:
Based on the overlap in genome sizes and gene counts my provisional position is that the gap between viruses and cellular organisms is narrower than generally expected.
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I haven't finished reading the paper on Mimivirus but you seem to know quite a bit about it - I saw something about part of its genome being pretty stable and the other highly variable and apparently borrowed from the host. Is that accurate to your understanding or did I misunderstand? And if it's accurate, could it suggest that Mimivirus' genome is being used in a different way from the "standard" way we think of (if such a thing exists), and this might imply a different relationship between genome size and complexity from that of cells or other viruses?
 This is not just a feature of mimivirus and allies. I expect that gene content is fairly uniform with vertebrate families. But in plants there is turnover in membership of gene families - cycles of duplication followed by neofunctionalisation, subfunctionalisation or loss - so you end up with a core genome and genes found within some but not all species of a group. Places to look at this are Gossypium, where we have genomes for at least 25 species, including 6 species of subgenus Karpas which have a common allotetraploid ancestry and which may show differential loss during the ongoing process of diploidisation, and other agriculturally important groups such as Brassica and Triticum.
 Generally as you go towards "simpler" organisms the magnitude of the contrast between the core genome and pangenome increases.
 In E. coli strains have between 4,000 and 5,500 genes (4,288 in the first sequenced strain), with a soft core (found in the great majority, but not all strains) of around 3,000 genes, a core genome of 1,000 genes, an a pangenome of 16,000 or more genes.
 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9205054/
https://en.wikipedia.org/wiki/Escherichia_coli
 Wolbachia pipientis gene contents are strikingly variable between strains symbiotic with different hosts.
 Mycoplasmas have a gene content of the order of 1,000 genes, a core genome of around 500 and a pangenome of well in excess of 30,000.
 https://www.nature.com/articles/s42003-021-02105-1
 Giant viruses (and pox viruses), with core genomes and substantial lineage specific genomes, don't seem out of line.
 The question that needs to be asked is to what extent this a genuine phenomenon, and to what extent it is an artefact of greater taxonomic splitting in charismatic megabiota. Is it correct to treat Buchnera aphidicola, Wolbachia pipientis and Escherichia coli as single species, or are they equivalent to a vertebrate genus, family, order or class?
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Like the prokaryotes thing it's not a claim, just an idea. I'd been wanting to dig into it a bit but haven't yet so I thought I'd ask you for thoughts anyway.
 
Ron Dean has just, indirectly, reminded me of Helacyton. Given the genomic instability of cancer lineages I suspect that also has a core genome, and a larger pangenome.
--
alias Ernest Major

Date Sujet#  Auteur
9 Apr 24 * Life: Turn it upside down!37JTEM
9 Apr 24 `* Re: Life: Turn it upside down!36Arkalen
9 Apr 24  `* Re: Life: Turn it upside down!35JTEM
9 Apr 24   +* Re: Life: Turn it upside down!31Arkalen
9 Apr 24   i+* Re: Life: Turn it upside down!12JTEM
9 Apr 24   ii`* Re: Life: Turn it upside down!11Arkalen
9 Apr 24   ii `* Re: Life: Turn it upside down!10JTEM
10 Apr 24   ii  `* Re: Life: Turn it upside down!9Arkalen
10 Apr 24   ii   `* Re: Life: Turn it upside down!8JTEM
10 Apr 24   ii    `* Re: Life: Turn it upside down!7Arkalen
10 Apr 24   ii     `* Re: Life: Turn it upside down!6JTEM
11 Apr 24   ii      `* Re: Life: Turn it upside down!5Arkalen
15 Apr 24   ii       `* Re: Life: Turn it upside down!4JTEM
16 Apr 24   ii        `* Re: Life: Turn it upside down!3Arkalen
17 Apr 24   ii         `* Re: Life: Turn it upside down!2JTEM
17 Apr 24   ii          `- Re: Life: Turn it upside down!1Arkalen
9 Apr 24   i`* Re: Life: Turn it upside down!18Ernest Major
10 Apr 24   i `* Re: Life: Turn it upside down!17Arkalen
10 Apr 24   i  `* Re: Life: Turn it upside down!16Ernest Major
10 Apr 24   i   `* Re: Life: Turn it upside down!15Arkalen
10 Apr 24   i    +* Re: Life: Turn it upside down!4Arkalen
10 Apr 24   i    i`* Re: Life: Turn it upside down!3Ernest Major
10 Apr 24   i    i +- Re: Life: Turn it upside down!1JTEM
10 Apr 24   i    i `- Re: Life: Turn it upside down!1Arkalen
10 Apr 24   i    `* Re: Life: Turn it upside down!10Ernest Major
11 Apr 24   i     `* Re: Life: Turn it upside down!9Arkalen
13 Apr 24   i      +* Re: Life: Turn it upside down!2Ernest Major
13 Apr 24   i      i`- Re: Life: Turn it upside down!1Arkalen
13 Apr 24   i      +* Re: Life: Turn it upside down!2Ernest Major
13 Apr 24   i      i`- Re: Life: Turn it upside down!1Arkalen
13 Apr 24   i      `* Re: Life: Turn it upside down!4Ernest Major
13 Apr 24   i       `* Re: Life: Turn it upside down!3Arkalen
14 Apr 24   i        `* Re: Life: Turn it upside down!2Ernest Major
16 Apr 24   i         `- Re: Life: Turn it upside down!1Ernest Major
12 Apr 24   `* Re: Life: Turn it upside down!3jillery
13 Apr 24    `* Re: Life: Turn it upside down!2JTEM
15 Apr 24     `- Re: Life: Turn it upside down!1jillery

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