Tag: science

Vertebrate-microbe symbiosis

Yet amazingly, there is an animal-that-screams-animal in which an alga also dwells. That would be the spotted salamander Ambystoma maculatum. When it is an embryo, cells of the alga Oophila amblystomatis somehow end up inside it. Technically, the salamander’s now a photosynthetic animal. This salamander is the sole known example of a vertebrate playing host to a symbiotic microorganism of any kind, photosynthetic or no. And needless to say, something very interesting — no one is yet sure exactly what — is going on between the 2. Past experiments have clearly shown that the salamander benefits from its unconventional living arrangements. How the algae feel about the situation has been rather less clear. Intracellular algae showed clear signs of stress and oxygen and sulfur deprivation, producing lots more heat shock and autophagy-related proteins in response to finding themselves inexplicably inside a salamander. So why does the Oophila, the salamander alga, put up with its apparently dreary living conditions inside its host? It’s an intriguing question that lacks a clear answer, but there are clues. The alga is found nowhere else in nature besides salamander egg capsules. Algal cells remain visible inside young salamanders for a long time. Even when they are no longer obvious, algal DNA remains detectable in adult salamanders in the oviducts and the male reproductive tract. Freshly laid eggs contain encysted algal cells. And those algal cells in the capsule don’t seem nearly as put-upon as those inside embryos. Where might they come from? Is it possible that the alga is passed from generation to generation of salamander, a perpetual part of the animal? If so, the salamander has given the algae the ultimate gifts: a free ride, a home, and immortality, at least for the life of the host species. If that is the case, it was probably a bargain worth making.

Octopus panspermia?

Evidence of the octopus evolution show it would have happened too quickly to have begun here on Earth. “Thus the possibility that cryopreserved Squid and/or Octopus eggs, arrived in icy bolides several 100M years ago should not be discounted as that would be a parsimonious cosmic explanation for the Octopus’ sudden emergence on Earth 270 ma BP.”

2022-01-29:

3 hearts, pumping blue-green blood because their oxygen carrying metal is copper (versus iron in the heme of our blood). They can spend 30 minutes out of the water, to scoot between tidepools.

Alien intelligence: from a distant branch in the tree of life, the octopus is the only invertebrate to have developed a complex, clever brain. Our common evolutionary ancestor is a tubule so ancient, neither brains nor eyes yet existed. They evolved independently, on land and by sea. From the Cambrian explosion of sensing, body plans, and predation, minds evolved in response to other minds. It was an information revolution. It’s where experience begins.

The octopus brain rings around its throat. 500M neurons, similar to dog (vs. human: 86B, fly: 100K).

The octopus has over 50 different functional brain lobes (versus 4 in human)

And furthermore, 60% of its neurons are out in the arms, with a high degree of autonomy. A severed arm can carry on as if nothing has changed for several hours.

It is a distributed mesh of ganglia (knots of nerves) in a ladder-like nervous system. Recurrent neural loops serve as a local short-term memory latch.

“The octopus is suffused with nervousness; the body is not a separate thing that is controlled by the brain or nervous system.” Unconstrained by bone or shell, “the body itself is protean, all possibility. The octopus lives outside the usual body/brain divide.” (PGS)

Structurally, our eyes ended up strikingly similar to the octopus (camera-like with a focusing lens, through a transparent cornea and iris aperture to a retina backing the optic nerves). But octopus eyes have a wide-angle panoramic view, and they move independently like a chameleon.

Their horizontal slit pupil stays horizontal as the body moves, like a steady cam. This is made possible by special balance receptors called statocysts (a sac with internal sensory hairs and loose mineralized balls that roll around with movement and gravity).

They can see polarized light, but not color (making their color-matching camouflage skills all the more intriguing; they also see with their skin).

Their playful interactions with humans exhibit mischief and craft, a sign of mental surplus

Humans internalized language as a tool for complex thought (we can hear what we say and use language to arrange and manipulate ideas). Octopuses are on a different path.

Their entire skin is a layered screen, with about a megapixel directly controlled by the brain.

Skin color, pattern and fleshy texture can change in 0.7 seconds.

3 layers of skin cells control elastic sacks of pigments, internal iridescent reflections, even polarization (which the octopus can see), over a white underbody. They are regulated by acetylcholine, one of the earliest neurotransmitters in evolution.

The octopus can create a voluntary light show on its skin, e.g., a dark cloud passing over the local landscape, or a dramatic display to confuse a predator while fleeing.

30 ritualized displays for mating and other signaling.

Some octopuses have regions of constant kaleidoscopic restlessness, like animated eye shadow.

1600 suckers. 16 kg of lift capacity per sucker. 10k tasting chemoreceptors per sucker. Each is controlled individually.

Octopus muscles have radial + longitudinal fibers (agile like our tongues, not our biceps).

Opposing waves of activation can create temporary elbows at the region of constructive overlap, or pass food sucker-to-sucker like a conveyor belt.

The octopus’ arm muscles can pull 100x its own weight.

It can squeeze through a hole about the size of its eyeball.

Their ink squirts contain oxytocin (perhaps to soothe prey) and dopamine, the “reward hormone” (perhaps to trick predators that they had caught the octopus in the billowy cloud).

2022-02-17:

Soft-bodied cephalopods such as the octopus are exceptionally intelligent invertebrates with a highly complex nervous system that evolved independently from vertebrates. Because of elevated RNA editing in their nervous tissues, we hypothesized that RNA regulation may play a major role in the cognitive success of this group. We thus profiled mRNAs and small RNAs in 18 tissues of the common octopus. We show that the major RNA innovation of soft-bodied cephalopods is a massive expansion of the miRNA gene repertoire. These novel miRNAs were primarily expressed in neuronal tissues, during development, and had conserved and thus likely functional target sites. The only comparable miRNA expansions happened, strikingly, in vertebrates. Thus, we propose that miRNAs are intimately linked to the evolution of complex animal brains.

In silico labeling

The new deep-learning network can identify whether a cell is alive or dead, and get the answer right 98% of the time (humans can typically only identify a dead cell with 80% accuracy) — without requiring invasive fluorescent chemicals, which make it difficult to track tissues over time. The deep-learning network can also predict detailed features such as nuclei and cell type (such as neural or breast cancer tissue).

Beta Thalassemia Breakthrough

The researchers’ hope was that the modified stem cells would mature into red blood cells and produce robust amounts of healthy hemoglobin. That hope was realized. 9 of the 2 patients suffered from severe beta thalassemia, and, after treatment, the number of blood transfusions they required fell by 74%. 3 of the 9 no longer need any transfusions at all. The same is true of 12 of the 13 patients with the less severe version of the disease. So far, the subjects of the trial have been observed for a maximum of 42 months, but they will be monitored long into the future, to insure that the benefits of the therapy persist and cause no serious side effects. 1 early concern—that the procedure could disrupt the DNA of the stem cells, potentially triggering leukemia—has not, fortunately, come to fruition.

Petawatt proton beams

NIF is the world’s only facility capable of achieving conditions like those in the interiors of stars and giant planets. Using ARC short-pulse generated proton beams for ultrafast heating of matter to extreme states will enable opacity and equation-of-state measurements at unprecedented energy-density states. In addition, “protons deposit their energy very specifically. That’s why protons are promising for applications such as tumor therapy. You can send a beam of protons toward a tumor and get it to deposit all of its energy exactly where you want it to without damaging other areas of the body. Likewise with a solid material. The proton beam deposits its energy where you want it to very quickly, so you can heat up a material really fast before it has time to hydrodynamically expand — your material stays dense, and that’s the name of the game — high energy, high density.”

A leg up in the afterlife

Archaeologists can only speculate about the motivation behind the unusual Virú burials. 1 suggestion is that the extra limbs may have served as a sacrificial offering to accompany the dead to the afterlife. Additional lab work will determine if there was any sort of relation between the individuals buried and the owners of the additional body parts.

New Chemistry, And Its Limits

So I enjoyed this paper very much, but it starts off with a claim that’s worth arguing about: “organic synthesis is still a rate-limiting factor in drug-discovery projects“. Is that true?

It depends on where you’re standing. All the synthetic limitations described above are real, and they keep us from being able to make a lot of molecules that we’d otherwise be cranking out. But (and this is a big point) it’s rarely the case that we medicinal chemists identify a tricky new structure that absolutely has to be made. That sounds odd, but it comes down to our predictive powers, which aren’t so great. We don’t generally draw some wild compound up on the hood sash and say “That’s the one, folks: find a way to make it or die trying”. We never know which is the one, so in the absence of knowing, we make the things that we can make in the ways that we can make them, and honestly, much of the time, we can manage to come up with something.

Many more hominins

It seems as if, every few weeks now, a new hominin fossil, genetic study, archaeological site, or re-dating of old sites is reported from the vast Asian continent, a continent that still has large swathes of areas yet to be intensively explored. If nothing else, the picture as it appears thus far is much more complicated than the old Out-of-Africa models: there were multiple earlier dispersals from Africa, and much more interbreeding between species than we once thought. The story of ourselves, it turns out, becomes richer the more we know about it.