Amazing stuff! Much more research is needed. Whether these investigated cells actually communicate by chemical or electrical signals is still an open question.
"Sponges are simple creatures, yet they are expert filter feeders, straining tens of thousands of litres of water through their bodies every day to collect their food. Their mastery of this complex behaviour is all the more remarkable because they have no brain, nor even a single neuron to their name. ...
that sponges use an intricate cell communication system to regulate their feeding and to potentially weed out invading bacteria ...
Previous research has found that sponges possess genes encoding proteins that typically help synapses to function, despite the animals’ lack of neurons. ...
that sponges use an intricate cell communication system to regulate their feeding and to potentially weed out invading bacteria ...
Previous research has found that sponges possess genes encoding proteins that typically help synapses to function, despite the animals’ lack of neurons. ...
To discover which cells were expressing these genes, [researchers] sequenced the RNA in various individual cells from a freshwater sponge (Spongilla lacustris).
They found that the sponge has 18 distinct cell types. Synaptic genes were active in a few of these types, which were clustered around the sponges’ digestive chambers. This suggests that some form of cellular communication might coordinate the animal’s filter-feeding behaviour. ...
The researchers then used X-ray imaging and electron microscopy to study one of these cell types, which they called secretory neuroid cells. The scans revealed that neuroids send out long arms to reach choanocytes, a type of cell with hair-like protrusions that drive sponges’ water-flow systems and capture most of their food. ...
On the basis of the proximity of the two cell types and the expression of genes that might allow for the secretion of chemicals, the researchers think that these arms enable neuroids to communicate with choanocytes, so that they can pause the water-flow system and clear out any debris or foreign microbes. However, these neuroid cells are not nerves, and there is no sign of the synapses that enable neurons to communicate so quickly. Instead, this cell type might represent an evolutionary precursor to a true nervous system ..."
The researchers then used X-ray imaging and electron microscopy to study one of these cell types, which they called secretory neuroid cells. The scans revealed that neuroids send out long arms to reach choanocytes, a type of cell with hair-like protrusions that drive sponges’ water-flow systems and capture most of their food. ...
On the basis of the proximity of the two cell types and the expression of genes that might allow for the secretion of chemicals, the researchers think that these arms enable neuroids to communicate with choanocytes, so that they can pause the water-flow system and clear out any debris or foreign microbes. However, these neuroid cells are not nerves, and there is no sign of the synapses that enable neurons to communicate so quickly. Instead, this cell type might represent an evolutionary precursor to a true nervous system ..."
"... Surveying the cell types in the freshwater sponge Spongilla lacustris, Musser et al. found that many genes important in synaptic communication are expressed in cells of the small digestive chambers. They found secretory machinery characteristic of the presynapse in small multipolar cells contacting all other cells and also the receptive apparatus of the postsynapse in the choanocytes that generate water flow and digest microbial food. These results suggest that the first directed communication in animals may have evolved to regulate feeding, serving as a starting point on the long path toward nervous system evolution. ..."
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