Later On

A blog written for those whose interests more or less match mine.

Archive for September 1st, 2020

By Losing Genes, Life Often Evolved More Complexity

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Viviane Callier writes in Quanta:

When Cristian Cañestro set out in the early 2000s to study how animals with brains and backbones evolved, he picked a sea squirt called Oikopleura as a useful subject. Like all sea squirts, it has a tiny brain and nerve cord, but unlike the others, Oikopleura doesn’t undergo a metamorphosis on its way to maturity. Cañestro thought that Oikopleura had perhaps retained simpler, more ancestral features than other sea squirts and could be a guide to what they had evolved from.

“And that was the start of my frustration,” said Cañestro, a professor of genetics, microbiology and statistics at the University of Barcelona and a group leader at its Institute for Research on Biodiversity. His team was unable to find certain genes within Oikopleura’s genome that should have been there because they are very conserved across animals. In particular, none of the genes involved in the synthesis, modification or degradation of retinoic acid were present. Nor was the receptor for retinoic acid. Yet retinoic acid signaling was thought to be essential for making a brain, nerve cord and other vital features. Furthermore, Oikopleura also lacks a gene that seemed critical for triggering the development of heart tissue.

“If you imagine a car in your mind, of course it has wheels, right? Now, what if I told you I found a car that has no wheels?” Cañestro asked. “We found a situation in which the things we thought were essential are not there, even though the structure [they make] is still there. And that makes you rethink the essentiality of some of the genes.”

Two surprising analyses that appeared in Nature Ecology & Evolution early this year have hammered home just how inessential genes can be, and how creatively evolution can deal with losing them. By analyzing hundreds of genomes from across the animal kingdom, researchers in Spain and the United Kingdom showed that a startling degree of gene loss pervades the tree of life.

Their results suggest that even early animals had relatively complex genomes because of an unprecedented spurt of gene duplication early in life’s history. Later, as lineages of animals evolved into different phyla with distinct body plans, many of their genes began to disappear, and gene loss continued to be a major factor in evolution thereafter. In fact, the loss of genes seems to have helped many groups of organisms split away from their ancestors and triumph over new environmental challenges.

Until recently, gene losses in evolution were difficult to study because “if you don’t see something, it might be because it’s not there, but it also might be that you can’t find it,” said Günter Theißen, a plant biologist at the Friedrich Schiller University Jena in Germany. Scientists thought gene losses might be most common among symbiotic or parasitic species, which can simplify themselves by outsourcing a lot of their functional needs to their partners or hosts.

The availability of more and higher-quality genomes, however, enabled researchers to examine patterns of gene loss across the entire animal kingdom and made it clear that the phenomenon is not confined to simplified or parasitic lineages and animal groups.“There were periods in the evolution of the animal kingdom where gene loss was not going together with periods of morphological simplification,” said Jordi Paps, an evolutionary biologist at the University of Bristol who studies comparative genomics, and a co-author of one of the two big genome analyses.

Recognition that gene loss has been important to evolution throughout the animal kingdom opens new doors for research. When geneticists need to understand what genes do, they can create laboratory mice with “knockout” mutations and see whether and how the animals cope with the loss. The discovery that nature has in effect been running its own extensive knockout experiments — not just with Oikopleura but with all kinds of complex organisms — should afford rich insights into how evolution shapes development (and vice versa), the focus of a discipline known as evo-devo.

Use It or Lose It

Gene losses in evolution may sound like damaging events, since genes confer the traits that make life and health possible. It’s true that if individuals lose a genuinely essential gene, they may die or fail to flourish, and natural selection will weed them out of the population. But in reality, the majority of gene losses during evolution are likely to be neutral, with no fitness consequences for the organism, says Michael Hiller, an evolutionary genomicist at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany.

The reason is that evolutionary gene losses often occur after some change in the environment or behaviors makes a gene less necessary. If a key nutrient or vitamin suddenly becomes more available, for example, the biosynthetic pathways for making it may become dispensable, and mutations or other genetic accidents may make those pathways disappear. Losses can also occur after a chance gene duplication, when the superfluous copy degenerates, since selection no longer preserves it.

Plants offer abundant examples of this “use it or lose it” strategy, because many plant species have . . .

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Written by Leisureguy

1 September 2020 at 2:54 pm

Posted in Evolution, Science

Russell Brand interviews Richard Ayoade

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I like both these guys and find them interesting. Fans of The IT Crowd (on Netflix now) will recognize Ayoade as Maurice Moss.

Written by Leisureguy

1 September 2020 at 10:08 am

Posted in Video

Fragrant shave

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An extremely smooth and comfortable shave today — the Yaqi DOC really is an excellent razor, and this little Yaqi brush is quite pleasant: a comfortable handle of nice heft. It comes with two knots, silvertip badger and the synthetic shown, and I find myself using the synthetic much more than the badger. It’s a fine synthetic and feels quite good, plus it makes an excellent lather, this morning the famous Mama Bear lather.

But I was struck particularly by the fragrances. Spellbound Woods is a favorite fragrance, and as I enjoyed lathering — the feel of the brush, the warmth of the lather, the thickness of the lather, and the fragrance of the lather — I got to thinking particularly about the fragrance and how most men are limited to the range of fragrances found in canned foams and shaving gels: a narrow range of bland fragrances.

I imagine marketing directors quickly put the kibosh on any strong or quirky fragrances. Their aim is not to please a portion of the market with a well-defined and assertive fragrance (and thus risk losing a larger portion that may not like the fragrance), but rather to avoid offending anyone. Thus fragrances are muted: the olfactory equivalent of institutional paint colors: off-white, taupe, light grey, pale green.

In contrast, artisan soapmakers go for fragrances that stand out — good example: Stirling Soap Company’s Texas on Fire. Or Chiseled Face’s Summer Storm (or Midnight Stag). Or Phoenix Artisan’s Planet Java Hive (or Cavendish — or Organism 46-B). They know they will only get a segment of shavers in any case, so they are will to play to that and produce fragrances that appeal to a segment.

Marketing directors at big corporations, though, tend to want the whole market, so they avoid anything that might be displeasing to anyone. They try to please everyone, and that is a route to mediocrity. They can get away with it only because shaving fragrances are below the attentional radar of the typical man, who has a lot on his mind: job issues, family well-being under pandemic conditions, political pressures, disease risk, and so on. Most men don’t have the bandwidth to be conscious of something as low-priority as the fragrance they enjoy (or don’t) during their morning shave. If they did pay attention to it, those bland fragrances will wither away quickly: they have nothing to offer — elevator music for the nose.

Beyond Spellbound Woods, I used a little of the Tendre Madeleine Eau de Parfum shown as an aftershave — not a lot, since this is less diluted than an EDT, but enough to provide the pleasure of the fragrance. notes:

Tendre Madeleine by Les Senteurs Gourmandes is an Oriental Spicy fragrance for women and men. Tendre Madeleine was launched during the 2000’s. The fragrance features orange, bitter almond, vanilla sugar, Mexican vanilla, spicy notes, and wheat.

You can see why I like it.

Written by Leisureguy

1 September 2020 at 9:57 am

Posted in Shaving

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