All posts tagged: Singlecelled

Blood cells originated from single-celled ancestors 700 million years ago

Blood cells originated from single-celled ancestors 700 million years ago

Published by Jenni Sidey

Blood cells carry a deep evolutionary history. A new analysis suggests their earliest ancestors were macrophage-like cells inherited from single-celled life. By tracing those lineages back 700 million years, the work opens a new window into immunity’s ancient roots. Blood does more than move oxygen and fight infection. It also carries a record of where animals came from. A new evolutionary analysis suggests that the roots of blood cells stretch back roughly 700 million years. That period was when the first multicellular animals were beginning to emerge. In that picture, some cells now circulating through vertebrate bodies may trace their origins to genetic programs inherited from single-celled ancestors. The work, led by researchers at Kyoto University, set out to answer a basic but stubborn question. Scientists know a great deal about what human and mouse blood cells do. However, they know much less about when those cells first appeared and how they split into the many lineages seen today. To tackle that, the team developed a new method for comparing gene expression profiles across cell …

Single-celled organism with no brain is capable of Pavlovian learning

Single-celled organism with no brain is capable of Pavlovian learning

Published by skeptic

Stentor coeruleus is a single-celled organism with unexpected abilities MELBA PHOTO AGENCY / Alamy A simple unicellular organism with no brain or neurons seems capable of an advanced form of learning. The simplest form of learning, known as habituation, is gradually reducing how much you respond to a repeated, harmless stimulus, like a smell or noise. This is common across all animals and has even been seen in plants. It has also been demonstrated in some protists, which have complex eukaryotic cells like animals, land plants and fungi, but are generally single-celled organisms, including the trumpet-shaped Stentor coeruleus and the slime mould Physarum polycephalum. Much more difficult is learning to connect different types of stimuli or events, and predicting that one is linked to another. Such associative learning was most famously demonstrated when Ivan Pavlov paired the sound of a bell with giving dogs food, resulting in the animals salivating when they heard the bell ring. Now, Sam Gershman at Harvard University and his colleagues have used similar conditioning experiments to show that Stentor seems capable of …