The franco german relationship in eukaryotic cell

Franco-German relations –

the franco german relationship in eukaryotic cell

Eukaryotic Cell Genetics reviews the state of knowledge in somatic cell genetics. The book begins by discussing the development of somatic cell genetics. Those of us who can read German and who have a copy of Altmann's book To Altmann, everything in eukaryotic cells consisted of bioblasts, including the .. (in French) the idea that there was a close relationship between bacteria and . The book then turns to the problem of the origin of the eukaryotic cell. possible evolutionary relationships between fungi, protozoa, and eukaryotic algae. It is clear that the author is quite happy reading French, German, and English, and.

In plants they correspond to the chloroplast endosymbiosis cyanobacteria [ 141920 ]. This chimaeric ancestry of eukaryotic cells involving archaebacterial and eubacterial partners is manifest not only in protein sequence conservation, but also in functional categories corresponding to informational and operational genes [ 2 ] and in gene expression patterns, protein interactions, and gene essentiality [ 4 ]. The intrinsic chimaerism of eukaryotic cells underscores the pivotal role of mitochondria in eukaryote evolution, and is readily explained through bioenergetics: Eukaryotes did not, however, inherit all of their attributes directly from their prokaryotic ancestors in ready-made form, because eukaryotes boast many lineage-specific inventions that have no fully fledged homologues in prokaryotes [ 23 ], such as the endoplasmic reticulum ER and its contiguous nuclear membrane, the Golgi complex, incoming and outgoing vesicles, and digestive vacuoles.

Various prokaryotes have made small steps towards complexity [ 21 ] and the genetic starting material for some eukaryotic traits such as cytoskeletal components [ 24 ], the cell division machinery [ 2526 ] or the ubiquitin signaling system [ 2728 ] can be identified in prokaryote genomes.

Nevertheless, it remains true that no prokaryote offers anything vaguely similar to the burgeoning complexity of a eukaryotic cell.

Planctomycetes and eukaryotes: a case of analogy not homology

This brings us to the issue. On the bottom line, those four papers are saying that the long sought missing links in the prokaryote to eukaryote transition [ 37 ] have finally been discovered. Those are exceptional claims by any measure. Exceptional claims demand exceptional evidence, as the recent report of bacteria with arsenate-based nucleic acids attests [ 38 — 47 ].

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  • Endosymbiotic theories for eukaryote origin
  • Planctomycetes and eukaryotes: a case of analogy not homology

For those who have been comparing genome sequence data for years to illuminate the prokaryotic roots of eukaryotes, the claims that PVC members are the evolutionary forerunners of eukaryotes comes as quite a surprise.

Here we inspect the evidence underlying such claims.

the franco german relationship in eukaryotic cell

Homology and analogy Proponents of the view that the PVC clade is the missing link in the evolutionary sequence linking prokaryotes and eukaryotes argue for homology of PVC characters with eukaryotic characters. However, the phylogenetic perspectives of those that propose a special role for PVC members in discussion of eukaryotic origins could not be more different. The other view [ 30 ] has it that the eukaryotic type of complex cell organization is ancestral to all life forms and that eubacteria and archaebacteria have undergone simplification, a scenario that was originally proposed in the context of the introns-early hypothesis 30 years ago [ 48 ], long abandoned by its proponents on the strength of multiple lines of evidence against introns early, and later rekindled as thermoreduction [ 49 ], as discussed elsewhere [ 18 ].

Thus, despite the polarity of these views, they both maintain that some traits of the PVC bacteria specifically link them to eukaryotes in an evolutionary chain, hence the characters are interpreted as homologous. In the context of genes and proteins, the term homologous means similar in sequence or structure by virtue of common ancestry. Darwin, Origin of Species, Penguin Classics Homology in molecular sequences can be examined using a database similarity measure such as that implemented in the BLAST suite of programs [ 50 ].

Schimper [ 11 ] is sometimes credited with the discovery of endosymbiotic theory, but his treatise of the topic is wholly contained in a footnote that translates to this: That was all he wrote on the possibility of symbiotic plastid origin.

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The sentence immediately following that one in Schimper's famous footnote, however, is also significant, as we will see in a later passage about Portier and the symbiotic origin of mitochondria; it translates to this: Clearly, Reinke was observing the proliferation of contaminating bacteria, not of free-living organelles.

Schimper [ 1112 ] did, however, champion the case that plastids proliferate through division. That was important for the Russian biologist Constantin Mereschkowsky, who probably delivered the first thoroughly argued case that some cells arose through the intracellular union of two different kinds of cells endosymbiosisin his paper [ 13 ] that has been translated into English [ 14 ]. Mereschkowsky [ 13 ] said three things: Mereschkowsky's scheme was more fully elaborated but basically unchanged in his series [ 15 ]: The branches in Mereschkowsky's tree occasionally unite via endosymbiosis to produce fundamentally and radically new kinds of organisms plants, for example [ 1516 ].

A more modern version of symbiosis in cell evolution would have to include the symbiotic origin of mitochondria, archaea and the concept of secondary endosymbiosis. Endosymbiotic theories have it that cells unite, one inside the other, during evolution to give rise to novel lineages at the highest taxonomic levels, via combination.

That is not the kind of evolution that Darwin had in mind; his view of evolution was one of gradualism. Many biologists still have a problem with the notion of endosymbiosis and hence prefer to envisage the origin of eukaryotes as the product of gene duplication, point mutation and micromutational processes [ 17 ]. A paper by the late Christian de Duve [ 18 ] is now often taken as the flagpole for micromutational theories of eukaryote origin, but de Duve, like the late Lynn Margulis [ 19 ], always categorically rejected the evidence that mitochondria and hydrogenosomes—anaerobic forms of mitochondria [ 2021 ]—share a common ancestor.

No anaerobic form of mitochondria ever fits into classical endosymbiotic theory. This is because classical Margulis's version of endosymbiotic theory [ 19 ] was based on the premise that the benefit of the endosymbiotic origins of mitochondria was founded in oxygen utilization, while de Duve's versions went one step further and suggested that even the endosymbiotic origin of peroxisomes was founded in oxygen utilization [ 18 ].

the franco german relationship in eukaryotic cell

Anaerobic mitochondria were never mentioned and hydrogenosomes, if they were mentioned, were explained away as not being mitochondria [ 1819 ]. The overemphasis of oxygen in endosymbiotic theory and how the focus on oxygen led to much confusion concerning the phylogenetic distribution and evolutionary significance of anaerobic forms of mitochondria has been dealt with elsewhere [ 22 — 24 ].


There is one alternative to classical endosymbiotic theory that took anaerobic mitochondria and hydrogenosomes into account, the hydrogen hypothesis [ 25 ]; it predicted i all eukaryotes to possess mitochondria or to have secondarily lost them, ii that the host for mitochondrial origins was an archaeon, the eukaryotic state having arisen in the wake of mitochondrial origins, and iii that aerobic and anaerobic forms should interleave on the eukaryotic tree.

Though radical at the time, prediction i was borne out [ 26 — 29 ], and so was prediction ii [ 30 — 32 ], as well as iii [ 2133 ].

the franco german relationship in eukaryotic cell

Furthermore, only recently, it has been recognized that the invention of eukaryotic specific traits required more metabolic energy per gene than prokaryotes have at their disposal, and that mitochondria afforded eukaryotic cells an orders of magnitude increase in the amount of energy per gene, which finally explains why the origin of eukaryotes corresponds to the origin of mitochondria [ 234 ].

In the s relationships remained good as Germany supported France during its difficulties with Britain over African colonies. Any lingering harmony collapsed inwhen Germany took an aggressively hostile position to French claims to Morocco. There was talk of war and France strengthened its ties with Britain and Russia. First World War[ edit ] Main articles: It is captioned with an 18th-century quote: In the chief pressure group was the Parti colonial, a coalition of 50 organizations with a combined total of members.

International relations — The Allied victory saw France regain Alsace-Lorraine and briefly resume its old position as the leading land power on the European continent. France was the leading proponent of harsh peace terms against Germany at the Paris Peace Conference. Since the war had been fought on French soil, it had destroyed much of French infrastructure and industry, and France had suffered the highest number of casualties proportionate to population.

Much French opinion wanted the Rhineland, the section of Germany adjoining France and the old focus of French ambition, to be detached from Germany as an independent country; in the end they settled for a promise that the Rhineland would be demilitarized, and heavy German reparation payments.

On the remote Eastern end of the German Empire, the Memel territory was separated from the rest of East Prussia and occupied by France before being annexed by Lithuania. To alleged German failure to pay reparations under the Treaty of Versailles inFrance responded with the occupation of the Rhineland and the industrial Ruhr area of Germany, the center of German coal and steel production, until Locarno treaties of [ edit ] Main article: Locarno Treaties In late German foreign minister Gustav Stresemann made his highest priority the restoration of German prestige and privileges as a leading European nation.

French withdrawal from the occupation of the Ruhr was scheduled for Januarybut Stresemann sensed that France was very nervous about its security and might cancel the withdrawal.

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He realized that France deeply desired a British guarantee of its postwar borders, but that London was reluctant.

Stresemann came up with a plan whereby all sides would get what they wanted through a series of guarantees set out in a series of treaties. British Foreign Minister Austen Chamberlain enthusiastically agreed. France realized that its occupation of the Ruhr Had caused more financial and diplomatic damage that was worth, went along with the plan.

The conference of foreign ministers they convened in the Swiss resort of Locarno and agreed on a plan. The first treaty was the most critical one: The second and third treaties called for arbitration between Germany and Belgium, and Germany and France, regarding future disputes. The fourth and fifth were similar arbitration treaties between Germany and Poland, and Germany and Czechoslovakia. Poland especially, and Czechoslovakia as well, felt threatened by the Locarno agreements and these treaties were attempts to reassure them.