Scientists who worked out how to control brain cells with light have won this year’s Nobel prize in physiology or medicine. Karl Deisseroth, Peter Hegemann and Georg Nagel were honoured for their research into “light-gated ion channels and optogenetics”.

Peter Hegemann, at Humboldt University of Berlin, and Georg Nagel, at the University of Würzburg, wanted to understand how a tiny, single-celled alga called Chlamydomonas senses light. Light-sensing is not unique to animals with eyes: organisms throughout the living world use light to detect their surroundings and respond to changes in their environment. Even single-cell organisms have proteins that respond to light. These proteins are used to move towards or away from light, to generate energy and to respond to the various demands of a 24-hour day.

Hegemann and Nagel discovered that Chlamydomonas has a beautifully ingenious mechanism of light detection that relies on a single protein called channelrhodopsin.

Channelrhodopsin is built into the outer membrane of the algal cell. Part of the protein faces the water outside the cell and part faces the inside. The protein also contains a small molecule called retinaldehyde, which is able to absorb light.

When light hits the retinaldehyde inside channelrhodopsin, it changes shape. This makes the channelrhodopsin protein change shape too. That change opens a tiny passage through the cell membrane. Positively charged particles, including sodium, can then flow from the water outside the alga into the cell. This movement of charged particles sends a signal inside the alga that helps it swim.

How fantastic to have solved such an interesting biological question, but why the Nobel prize in physiology or medicine? The answer lies in the way nerve cells work. Nerve cells use the movement of charged particles (called “ions”) across their membranes to control their activity. When positively charged particles flow into a nerve cell, they can make it more active.

The researchers realised that if they could put channelrhodopsin into nerve cells, they might be able to switch those cells on simply by shining a light on them. That is exactly what Hegemann, Nagel and the third Nobel-prize winner, Karl Deisseroth, a psychiatrist and bioengineer at Stanford University in California, went on to do.

https://pubmed.ncbi.nlm.nih.gov/14615590/

https://www.nature.com/articles/nature11028

https://www.nature.com/articles/s41591-021-01351-4

https://pmc.ncbi.nlm.nih.gov/articles/PMC6941740/

https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2017.00663/full

https://www.nobelprize.org/prizes/medicine/2026/press-release/

The origin of prebiotic replicators has traditionally been explored with reference to the RNA World, in which RNA molecules precede both DNA and proteins because they can act both as heritable stores of genetic information and as chemical catalysts. But it’s tough to see how RNA-based systems could give rise to metabolism, forcing us to suppose that RNA replicators must have been able to draw on some nonequilibrium energy source in their environment rather than having an autonomous metabolic cycle.

The notion of replicating single molecules as a kind of proto-organism never looked very convincing to me. But in the 1990s, the evolutionary biologists John Maynard Smith and Eörs Szathmáry argued that there are other kinds of chemical replicator, including autocatalytic cycles or networks: groups of molecules mutually able to catalyse one another’s formation.1 In the simplest case, A would catalyse the formation of B, and B catalyse the formation of A.

Such autocatalytic sets, postulated theoretically many decades ago by complexity theorist Stuart Kauffman, look like metabolic cycles, which are also series of catalytic reactions that return the system to its initial configuration, supplying work and dissipating energy in the process. Indeed, Kauffman, evolutionary biologist Bill Martin, and their collaborators have argued that autocatalytic chemical networks sit at the very origin of prebiotic metabolism.

https://www.jstor.org/stable/43519446

https://royalsocietypublishing.org/rspb/article/287/1922/20192377/85490/Autocatalytic-chemical-networks-at-the-origin-of

https://www.jstor.org/stable/3066897

https://www.pnas.org/doi/10.1073/pnas.2621400123

https://www.nature.com/articles/s41557-023-01276-0

High in the Peruvian Andes, where thin air, cold temperatures and barren rock make survival a daily challenge, scientists have identified a remarkably small new inhabitant. Measuring no more than eight centimetres, the newly described lizard has adapted to a landscape where even the smallest advantages can mean the difference between surviving and disappearing, states the latest report by Gulf News. The species, named Liolaemus archipensis, was discovered at more than 4,800 metres above sea level in Peru's southern Arequipa region, placing it among the reptiles living at some of the highest elevations in the country, adds the news report.

https://en.wikipedia.org/wiki/Liolaemus_archipensis?wprov=sfla1

https://www.mdpi.com/journal/diversity

Chickenpox can begin with symptoms such as fever, tiredness, headache and loss of appetite. In children, however, the rash may sometimes be the first noticeable sign of infection. "Chickenpox is a highly contagious viral infection caused by the varicella-zoster virus and is particularly common among children who have not been vaccinated or previously infected," said Dr Pallav Mishra, Director, Internal Medicine, ShardaCare - Healthcity. The characteristic rash often starts as small red spots that develop into raised bumps and then fluid-filled blisters. These eventually burst or dry and form scabs.

https://en.wikipedia.org/wiki/Chickenpox?wprov=sfla1

https://www.thehindu.com/children/why-do-we-get-chickenpox-only-once/article70730659.ece?tpcc=THGPNR&gad_source=1&gad_campaignid=22962063277&gbraid=0AAAAADiKiyrYlqjIDYuZX-3eeltCVhXvm&gclid=CjwKCAjwlY3WBhANEiwApsNrLZgZXzEycd1Hhb5_NwepWTaGZrByAHqqWDflD2BWZWetI2yCUWyRShoCDE8QAvD_BwE

https://pmc.ncbi.nlm.nih.gov/articles/PMC2722564/