biology
The Daily Planet #124: The Anatomical Compiler
Michael Levin is an interesting thinker; a rare Platonist in Biology. This quote from a recent post of his makes me think of biological engineering, but not the kind where we force organisms to do our willing, but rather work with their agential capacity to produce forms that we need:
Paralogs
Seeing before LUCA. Most genes trace back to the Last Universal Common Ancestor (~4.2 billion years ago) and stop — a barrier beyond which we cannot see. But universal paralogs are different: rare gene families present in all organisms today that were duplicated BEFORE LUCA. Both copies were inherited by all descendants. These ancient pairs pierce through the barrier, letting us glimpse evolution that predates the origin of all modern life. All known universal paralogs involve protein synthesis or membrane transport — the oldest functions.
Assembloid
Lab-grown brain circuits reveal who's really in charge. Nagoya University researchers fused thalamic and cortical organoids derived from human iPS cells, watching axons extend bidirectionally to form synapses. Neural activity propagates from thalamus to cortex in wave-like patterns, selectively synchronizing pyramidal tract (PT) and corticothalamic (CT) neurons while intratelencephalic (IT) neurons remain unaffected. The thalamus plays a decisive role in cortical maturation — connected organoids show greater development than isolated ones.
Plectoneme
DNA through nanopores: not knots, but twisted coils. For decades, scientists thought messy electrical signals during nanopore sequencing were caused by DNA knots. Zheng & Keyser (Cavendish Laboratory, Physical Review X 2025) discovered they're actually plectonemes — twisted structures like a phone cord. Electroosmotic flow inside the pore spins the DNA helix, torque propagates along the strand, and regions outside the pore coil up. Nicked DNA (with breaks) can't propagate twist, confirming the mechanism.
Silk
Spider silk's molecular transformation from liquid to fiber. Based on King's College London / SDSU research (Feb 2026) revealing how arginine-tyrosine 'stickers' drive silk formation. Cation-π interactions between these amino acids initiate liquid-liquid phase separation (LLPS), then persist during β-sheet crystallization as shear forces convert the dope into fiber. The result: material stronger than steel, tougher than Kevlar, from a simple molecular trick.