More than 1.6 billion years ago, one cell engulfed another and put it to work. More specifically, a eukaryotic cell, the sort of cell that contains distinct structures with different functions, took in a blue-green bacterium that could do something it could not: use sunlight to make sugars. The ancient eukaryote then reproduced the bacterium in all of its cells, making it a permanent part of the intracellular environment. What was once an independent microbe was now the chloroplast: the cellular structure, or organelle, that plant cells use to photosynthesize. They’ve been together ever since, an absorption known as endosymbiosis.
Nor, scientists think, were chloroplasts the only parts of cells that were once bacteria: Mitochondria, organelles that produce energy in plant and animal cells, got their start the same way, and some other organelles may have, as well. Now researchers have found another useful bacterium that they think is on its way to becoming a modern organelle of another eukaryotic cell—this time, an alga rather than a plant or animal. Studying this relationship would allow scientists to witness endosymbiosis in action, something they had long theorized but never seen.
What’s the News: If you’ve ever been told been that a massage is good for “releasing toxins”—or to sound more scientific, “lactic acid”—from your muscles, then you’ve been told wrong. Turns out muscle cells do like a good massage, but it has nothing to do with lactic acid.
In the first study on the cellular effects of massage post-exercise, researchers found that massage bolsters chemical signals reducing inflammation and promoting repair of muscle cells.
Artist’s rendering of a mitochondrian, the energy-producing
cellular structure affected by ARSACS
Scientists have pinpointed the cause of a rare, fatal neurodegenerative disorder called ARSACS, or autosomal recessive spastic ataxia of Charlevoix-Saguenay. The disease is due to defects in neuron’s mitochondria, the bit of biological machinery that generates energy for the cell—a structure known to be affected in Parkinson’s, Alzheimer’s, and other neurological diseases, as well.
ARSACS was first observed in the descendants of a small group of 17th century French settlers who made their homes near the Charlevoix and Saguenay rivers in what is now Quebec, and has since been seen worldwide. But its incidence remains unusually high in that particular French Canadian community, with 1 in 1,500 to 2,000 people developing ARSACS and 1 in 23 people unaffected genetic carriers of the disease.