stem mammal

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introductory bios? for my ocs?

yeah, so I’ve got quite a few of them that I’ve accumulated over the years. I still need to throw a character page up so people can have an idea of who/what they are…

they do not all exist in the same universe (or at least, these versions of them don’t). Sam, Ike, Terry, and Mira all exist in a sci-fantasy dystopia with psychic people and lycomorphs (aka werewolves if werewolves were humans rapidly devolving/re-evolving into a stem mammal-like beast form), Roach is from a dumpy vampire world, Mauve is from an edgy Pokemon AU me and my gf made, and Ancha (sometimes also called Alice in AUs) exists in a surreal seapunk Atlantis and Dylan tags along.

I like, have thought way too much about these guys and welcome questions about them.

The name Tetraceratops (“four-horned face”) sounds like it should belong to some sort of large horned dinosaur, doesn’t it? Perhaps a relative of Triceratops or Pentaceratops.

Well, nope! Tetraceratops was actually a small synapsid (a “proto-mammal”) from the Early Permian of Texas, USA, living about 279-272 million years ago. Known only from a 9cm long skull (3.5″), it had two sets of saber teeth in its jaws and a total of six horns on its face instead of four – two on its snout, two in front of its eyes, and two at the back of its jaws.

It’s unclear exactly what the rest of its body looked like, or even where it belongs in the synapsid family tree – but currently it’s thought to be the earliest known member of the therapsids. I’ve reconstructed it here to look similar to other basal therapsids like Herpetoskylax.

Lystrosaurus murrayi, a non-mammalian therapsid from the Early Triassic of Southern Pangaea (an area that later became Africa, India, and Antarctica), living about 250 million years ago.

Only about 50cm long (~19.5in), these tubby little creatures were one of the few survivors of the worst mass extinction in Earth’s history. For a few million years after the extinction the various species of Lystrosaurus were so successful that they were the single most common land vertebrate in the world, making up 95% of the population.

Researchers observe stem cell specialization in the brain

Adult stem cells are flexible and can transform themselves into a wide variety of special cell types. Because they are harvested from adult organisms, there are no ethical objections to their use, and they therefore open up major possibilities in biomedicine. For instance, adult stem cells enable the stabilization or even regeneration of damaged tissue. Neural stem cells form a reservoir for nerve cells. Researchers hope to use them to treat neurodegenerative disorders such as Parkinson’s and Alzheimer’s disease. Tübingen researchers led by Professor Olga Garaschuk of the University of Tübingen’s Institute for Physiology, working with colleagues from Yale University, the Max Planck Institute of Neurobiology in Martinsried and the Helmholtz Center in Munich, studied the integration of these cells into the pre-existing neural network in the living organism. The results of their study have been published in the latest edition of Nature Communications.

There are only two places in the brains of adult mammals where stem cells can be found – the lateral ventricles and the hippocampus. These stem cells are generating neurons throughout life. The researchers focused on a stem cell zone in the lateral ventricle, from where progenitors of the nerve cells migrate towards the olfactory bulb. The olfactory nerves which start in the nasal tissue run down to this structure, which in mice is located at the frontal base of the brain. It is there that the former stem cells specialized in the task of processing information on smells detected by the nose. “Using the latest methods in microscopy, we were for the first time able to directly monitor functional properties of migrating neural progenitor cells inside the olfactory bulb in mice,” says Olga Garaschuk. The researchers were able to track the cells using special fluorescent markers whose intensity changes according to the cell’s activity.

The study showed that as little as 48 hours after the cells had arrived in the olfactory bulb, around half of them were capable of responding to olfactory stimuli. Even though the neural progenitor cells were still migrating, their sensitivity to odorants and their electrical activity were similar to those of the surrounding, mature neurons. The mature pattern of odor-evoked responses of these cells strongly contrasted with their molecular phenotype which was typical of immature, migrating neuroblasts. “Our data reveal a remarkably rapid functional integration of adult-born cells into the pre-existing neural network,” says Garaschuk, “and they show that sensory-driven activity is in a position to orchestrate their migration and differentiation as well as their decision of when and where to integrate.”