The Rise and Fall of TRP-N, an Ancient Family of Mechanogated Ion Channels, in Metazoa.
Bottom Line: In flies, the transient-receptor-potential N protein (TRP-N) was found to be a cilia-associated mechanoreceptor.We propose that these new candidate proteins help explain the sensory complexity of Cnidaria which has been previously observed but so far has lacked a molecular underpinning.Also, the ancient appearance of TRP-N supports a common origin of important components of the nervous systems in Ctenophores, Cnidaria, and Bilateria.
Affiliation: Institute for Evolution and Biodiversity, University of Muenster, Germany.Show MeSH
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Mentions: We next aimed to localize expression of TRP-Ns and distinguish possible spatial differences in their expression. In situ hybridization (see Materials and Methods for details) was used to localize TRP-N1 and TRP-N2 mRNAs. Due to a lack of unique sequences, specific probes for the other TRP-N mRNAs were not feasible. Expression patterns of both hydra-TRP-N1 and hydra-TRP-N2 reveal a clear restriction to developing nematocytes in the body column of hydra, with hydra-TRP-N1 showing a stronger signal than Hydra-TRP-N2 (see fig. 3A and B). This strong hydra-TRP-N1 signal (see fig. 3A) refers to cell clusters of nascent, premature nematocytes (Fawcett et al. 1959). These clusters are known to break up upon maturation and the isolated nematocytes subsequently migrate toward the tentacles (Campbell and Marcum 1980). This expression pattern of hydra-TRP-N1 and hydra-TRP-N2 resembles the ones of most nematocyst-associated genes, such as minicollagens, which are downregulated in the head region (Beckmann and Özbek 2012).Fig. 3.—
Affiliation: Institute for Evolution and Biodiversity, University of Muenster, Germany.