Wer immer noch Befürchtungen hat, mit Genklempnerei stünde uns Horrendes ins Haus, dem sei ein Blick hierauf empfohlen. Das Ausbleiben aller "Durchbrüche" in diesem Belang war zwar schon ein vielsagender Hinweis, wurde aber von Kritikern (man möchte sagen: selbstredend) ignoriert. Die unentwirrbaren Interdependenzen in der genetischen Steuerung intrazellulärer Vorgänge lassen die Aussicht auf gezielte Eingriffe/Steuerung aussichtslos erscheinen. Es bedeutet auch, daß aussichtslos erscheinende Forschungsansätze dazu führen, daß sie nicht verfolgt werden.

https://www.quantamagazine.org/how-many-...-them-20180419/

How Many Genes Do Cells Need? Maybe Almost All of Them

Zitat von Quanta Magazine, Apr 19, 2018

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An ambitious study in yeast shows that the health of cells depends on the highly intertwined effects of many genes, few of which can be deleted together without consequence.

By knocking out genes three at a time, scientists have painstakingly deduced the web of genetic interactions that keeps a cell alive. Researchers long ago identified essential genes that yeast cells can’t live without, but new work, which appears today in Science, shows that looking only at those gives a skewed picture of what makes cells tick: Many genes that are inessential on their own become crucial as others disappear. The result implies that the true minimum number of genes that yeast — and perhaps, by extension, other complex organisms — need to survive and thrive may be surprisingly large.
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In the paper out today in Science, Kuzmin, Boone, Andrews and their collaborators at the University of Toronto, the University of Minnesota and elsewhere report that effort has yielded a deeper and more detailed map of the cell’s inner workings. Unlike in the double mutant experiments, the researchers did not make every possible combination of mutations — there are about 36 billion different ways to knock out three genes in yeast. Instead, they looked at the pairs of genes they’d already knocked out and ranked their interactions according to severity. They took a number of those pairs, whose effects ranged from making cells grow a little slower to making them significantly impaired, and matched them up one by one with knockouts of other genes, generating about 200,000 triple mutant strains. They monitored how quickly colonies of the mutant yeast grew, and after noting which mutants were struggling, they checked databases to see what the disabled genes were thought to do.
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Yeast geneticists were never under the impression that only essential genes mattered. But the new paper reinforces the idea that simplistic interpretations of just what is important in the yeast genome are likely to be flawed. The reality is more complicated, Boone and Andrews say. They suggest that when double and triple interactions are taken into account, the number of genes that a yeast cell truly can’t do without jumps. As their paper notes, the minimum genome needed for yeast cells to avoid a substantial defect “may nearly approach the complete set of genes encoded in the genome.”
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Ignorant as science may still be about certain happenings in yeast, it’s dwarfed by our ignorance of what is going on in our own cells. Part of what makes a project like this one at the University of Toronto possible is that yeast has been heavily studied and its genes intricately annotated by several generations of biologists, to a degree not yet reached with the human genome, which is comparatively enormous, rambling and full of mysteries. Still, the researchers say that they hope that as gene-editing technology for human cells advances, these kinds of experiments can help reveal more about the workings of cells and how the genes within a genome relate to one another. “I think there are many basic rules of genome biology we have not discovered,” Andrews said.

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