Cnidocytes, commonly known as stinging cells, are a type of cell found in corals and jellyfish, according to new Cornell research. It makes us cautious while wading in the sea, and it's also a fantastic model for better understanding the creation of new cell kinds.
Leslie Babonis, assistant professor of ecology and evolutionary biology in the College of Arts and Sciences, demonstrated that these stinging cells evolved by repurposing a neuron inherited from a pre-cnidarian ancestor in new research published in the Proceedings of the National Academy of Sciences on May 2.
"These unexpected findings show how new genes gain new functions to drive biodiversity diversification," Babonis added. "They show that throughout the early evolution of mammals, co-option of ancestral cell types was an essential source of new cell activities."
One of the major issues in evolutionary biology, according to Babonis, is figuring out how specialised cell types, such as stinging cells, emerge. Cnidocytes have been known to grow from a pool of stem cells that also give rise to neurons (brain cells) for over a century, but no one knew how those stem cells choose whether to create a neuron or a cnidocyte until now. Babonis believes that studying this mechanism in current cnidarians can offer information about how cnidocytes developed in the first place.
Cnidocytes (Greek for "stinging nettle") are a type of cell found in the phylum Cnidaria that may launch a toxic barb or glob, as well as stun prey or discourage attackers. Cnidarians are the only creatures with cnidocytes, whereas neurons are found in many animals, according to Babonis. To learn how a neuron may be reprogrammed to generate a new cell, she and her colleagues at the University of Florida's Whitney Lab for Marine Bioscience researched cnidarians, notably sea anemones.
"An explosive organelle (a small pocket inside the cell) stores the harpoon that blasts out to sting you," Babonis explained. "Because these harpoons are formed of a protein found exclusively in cnidarians, cnidocytes appear to be one of the clearest instances of how a new cell type emerges."
The researchers demonstrated that cnidocytes form by turning down the expression of a neuropeptide called RFamide in a subpopulation of developing neurons and repurposing those cells as cnidocytes using functional genomics in the starlet sea anemone Nematotostella vectensis. Furthermore, the researchers discovered that a single cnidarian-specific regulatory gene is responsible for both turning off and turning on the neurological activity of those cells.
Neurons and cnidocytes are similar in appearance, according to Babonis; both are secretory cells capable of ejecting material from the cell. Neuropeptides are proteins secreted by neurons that quickly transfer information to other cells. Poison-laced harpoons are secreted by cnidocytes.
"A single gene functions like a light switch: when it's on, you get a cnidocyte, and when it's off, you get a neuron," Babonis explained. "The logic for managing cell identity is rather simple."
This is the first study to establish that this logic exists in a cnidarian, therefore this trait was likely to regulate how cells differentiated from one another in the earliest multicellular animals, according to Babonis.
sources : latestly
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