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A view to kill.

Holstein TW - BMC Biol. (2012)

Bottom Line: Genome and proteome data from Hydra magnipapillata have opened the way for the molecular analysis of an ancient nervous system, which includes stinging cells, an unusual neurosensory and neurosecretory cell type.They hold some surprises for the mechanisms and evolution of sensory transduction that could not have been anticipated from what has been learned from flies and vertebrates.Research in BMC Biology now implicates the ancient opsin-mediated transduction pathway in the neuronal control of stinging cell discharge.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Organismal Studies Heidelberg, Heidelberg University, INF 230, 69120 Heidelberg, Germany. thomas.holstein@cos.uni-heidelberg.de

ABSTRACT
Genome and proteome data from Hydra magnipapillata have opened the way for the molecular analysis of an ancient nervous system, which includes stinging cells, an unusual neurosensory and neurosecretory cell type. They hold some surprises for the mechanisms and evolution of sensory transduction that could not have been anticipated from what has been learned from flies and vertebrates. Research in BMC Biology now implicates the ancient opsin-mediated transduction pathway in the neuronal control of stinging cell discharge.

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Cellular organization of a battery cell complex in Hydra. (a) Schematic representation showing the location of the different cell types in a battery cell complex. (Adapted from Figure 1e of [6]). (b, c) Double staining of tentacle tissue of Hydra magnipapillata with the monoclonal antibodies (b) NVl (neuron-specific, green) and (c) H22 (nematocyte-specific, red) shows innervation of the nematocytes (arrowheads indicate (b) the NV1+ nerve cell body and (c) four large nematocysts in different battery cells). (Reproduced from Figure 1a, b of [6]). (d, e) Staining of tentacle tissue with (d) NV1 monoclonal antibodies and (e) the CnAsh probe, which detects the product of achaete-scute, a gene specifically expressed in nematocytes and the sensory neurons of battery cells. (Reproduced from Figure 5 of [8]). Scale bar: 25 μm (b, c); 5 μm (e, d).
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Figure 1: Cellular organization of a battery cell complex in Hydra. (a) Schematic representation showing the location of the different cell types in a battery cell complex. (Adapted from Figure 1e of [6]). (b, c) Double staining of tentacle tissue of Hydra magnipapillata with the monoclonal antibodies (b) NVl (neuron-specific, green) and (c) H22 (nematocyte-specific, red) shows innervation of the nematocytes (arrowheads indicate (b) the NV1+ nerve cell body and (c) four large nematocysts in different battery cells). (Reproduced from Figure 1a, b of [6]). (d, e) Staining of tentacle tissue with (d) NV1 monoclonal antibodies and (e) the CnAsh probe, which detects the product of achaete-scute, a gene specifically expressed in nematocytes and the sensory neurons of battery cells. (Reproduced from Figure 5 of [8]). Scale bar: 25 μm (b, c); 5 μm (e, d).

Mentions: Much remains to be learned about the control of nematocyst discharge. In all cnidarians, discharge can be modulated by chemo- and mechanoreceptors, and it is also under inhibitory control upon satiation [4,5]. In sea anemones, the regulation of nematocyte exocytosis involves an adjacent mechanoreceptor complex, which consists of a sensory neuron with a kinocilium, surrounded by a bundle of stereocilia arising from hair cells [4]. The chemoreceptors are probably G-protein coupled and mechanotransduction involves transient receptor potential (TRP) ion channels, which are responsible for detecting a range of chemical and mechanical stimuli in vertebrates. Of particular interest is TRPA1, a pain and mechanoreceptor in vertebrates [5]. This stress sensor also occurs in the hair bundles of sensory neurons that are associated with nematocytes in sea anemones [4]. TRPA1 is encoded by the genome of Hydra magnipapillata, but we do not yet know whether it is also involved in the control of nematocyst discharge in Hydra. The hair-bundle-like sensory apparatus of Hydra is formed by the nematocyte itself, and it surrounds the kinocilium (known as the cnidocil) and the docking site of the nematocyst vesicle (Figure 1a). Also in Hydra, a sensory cell bearing a single cilium can be found in close proximity to the nematocytes [6]. This sensory cell was proposed to be a chemoreceptor, and it innervates up to 30 different nematocytes [6]. The latter are arranged in battery complexes (Figure 1) and as many as three batteries of nematocytes can be connected in this way (Figure 1).


A view to kill.

Holstein TW - BMC Biol. (2012)

Cellular organization of a battery cell complex in Hydra. (a) Schematic representation showing the location of the different cell types in a battery cell complex. (Adapted from Figure 1e of [6]). (b, c) Double staining of tentacle tissue of Hydra magnipapillata with the monoclonal antibodies (b) NVl (neuron-specific, green) and (c) H22 (nematocyte-specific, red) shows innervation of the nematocytes (arrowheads indicate (b) the NV1+ nerve cell body and (c) four large nematocysts in different battery cells). (Reproduced from Figure 1a, b of [6]). (d, e) Staining of tentacle tissue with (d) NV1 monoclonal antibodies and (e) the CnAsh probe, which detects the product of achaete-scute, a gene specifically expressed in nematocytes and the sensory neurons of battery cells. (Reproduced from Figure 5 of [8]). Scale bar: 25 μm (b, c); 5 μm (e, d).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3293708&req=5

Figure 1: Cellular organization of a battery cell complex in Hydra. (a) Schematic representation showing the location of the different cell types in a battery cell complex. (Adapted from Figure 1e of [6]). (b, c) Double staining of tentacle tissue of Hydra magnipapillata with the monoclonal antibodies (b) NVl (neuron-specific, green) and (c) H22 (nematocyte-specific, red) shows innervation of the nematocytes (arrowheads indicate (b) the NV1+ nerve cell body and (c) four large nematocysts in different battery cells). (Reproduced from Figure 1a, b of [6]). (d, e) Staining of tentacle tissue with (d) NV1 monoclonal antibodies and (e) the CnAsh probe, which detects the product of achaete-scute, a gene specifically expressed in nematocytes and the sensory neurons of battery cells. (Reproduced from Figure 5 of [8]). Scale bar: 25 μm (b, c); 5 μm (e, d).
Mentions: Much remains to be learned about the control of nematocyst discharge. In all cnidarians, discharge can be modulated by chemo- and mechanoreceptors, and it is also under inhibitory control upon satiation [4,5]. In sea anemones, the regulation of nematocyte exocytosis involves an adjacent mechanoreceptor complex, which consists of a sensory neuron with a kinocilium, surrounded by a bundle of stereocilia arising from hair cells [4]. The chemoreceptors are probably G-protein coupled and mechanotransduction involves transient receptor potential (TRP) ion channels, which are responsible for detecting a range of chemical and mechanical stimuli in vertebrates. Of particular interest is TRPA1, a pain and mechanoreceptor in vertebrates [5]. This stress sensor also occurs in the hair bundles of sensory neurons that are associated with nematocytes in sea anemones [4]. TRPA1 is encoded by the genome of Hydra magnipapillata, but we do not yet know whether it is also involved in the control of nematocyst discharge in Hydra. The hair-bundle-like sensory apparatus of Hydra is formed by the nematocyte itself, and it surrounds the kinocilium (known as the cnidocil) and the docking site of the nematocyst vesicle (Figure 1a). Also in Hydra, a sensory cell bearing a single cilium can be found in close proximity to the nematocytes [6]. This sensory cell was proposed to be a chemoreceptor, and it innervates up to 30 different nematocytes [6]. The latter are arranged in battery complexes (Figure 1) and as many as three batteries of nematocytes can be connected in this way (Figure 1).

Bottom Line: Genome and proteome data from Hydra magnipapillata have opened the way for the molecular analysis of an ancient nervous system, which includes stinging cells, an unusual neurosensory and neurosecretory cell type.They hold some surprises for the mechanisms and evolution of sensory transduction that could not have been anticipated from what has been learned from flies and vertebrates.Research in BMC Biology now implicates the ancient opsin-mediated transduction pathway in the neuronal control of stinging cell discharge.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Organismal Studies Heidelberg, Heidelberg University, INF 230, 69120 Heidelberg, Germany. thomas.holstein@cos.uni-heidelberg.de

ABSTRACT
Genome and proteome data from Hydra magnipapillata have opened the way for the molecular analysis of an ancient nervous system, which includes stinging cells, an unusual neurosensory and neurosecretory cell type. They hold some surprises for the mechanisms and evolution of sensory transduction that could not have been anticipated from what has been learned from flies and vertebrates. Research in BMC Biology now implicates the ancient opsin-mediated transduction pathway in the neuronal control of stinging cell discharge.

Show MeSH
Related in: MedlinePlus