Life fast, diapause young: The African turquoise killifish genome

killifish


Your newly sequenced genome isn’t going to get into Nature, Science, or Cell just because it “hasn’t been done before”. You need to have a hook. And speaking of hooks, there are two new fish genome papers out in Cell! (and you’re welcome for that punny transition)

The new genome is from a pretty strange species. No, not the water bear, which has two inconsistent recent genomes. It’s from the African turquoise killifish. The killifish is an interesting species because, like the tardigrade, it has a state of diapause (“suspended animation”) in its life history. These Zimbabwean and Mozambican fish have drought resistant embryos that can survive for 6-8 months until they hatch during the rainy season when the ephemeral ponds return.

Because only the embryos are drought resistant, the adults have some of the shorted vertebrate lifespans. In fact, the authors mention that they are the shortest-lived vertebrate that can be bred in captivity. So, when we have an interesting species, what do we do? We sequence the genome!

The two papers can be summed up as:
1) They assembled the killifish genome (and did a darn good job).
2) They found genes that were under positive selection.
3) Some of these genes are related to aging (although the authors point out that the overlap with previously-published aging-related genes was “not statistically significant”, suggesting that it is a random intersection of genes).
4) Genes that are associate with lifespan between two captive strains (with different lifespans) are clustered on the sex chromosome.
5) RNA-seq revealed that the transcriptional pathways involved in embryonic diapause are (somewhat) similar to those that are involved in aging.

So the authors conclude that selection on lifespan, either shorter or longer, may have affected the same genes, and that this is an exceptionally interesting species in which to study aging.

So there you go. That the recipe for publishing two Cell papers with one new genome!

(note that Cell apparently also requires that you include a bunch of multi-panel circle plots with pictures of people’s faces and other species…)

REFERENCES
Valenzano DR, Benayoun BA, Singh PP et al. (2015) The African Turquoise Killifish Genome Provides Insights into Evolution and Genetic Architecture of Lifespan. Cell, 163, 1539–1554.

Reichwald K, Petzold A, Koch P et al. (2015) Insights into Sex Chromosome Evolution and Aging from the Genome of a Short-Lived Fish. Cell, 163, 1527–1538.

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About Noah Snyder-Mackler

I'm a postdoctoral fellow in the department of Evolutionary Anthropology at Duke University. Broadly, I study non-human primate genetics and genomics. More specifically, I'm interested in the interaction between behavior, genotype, and gene expression in response to social stress.
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