ArCRHP mRNA expression in Asterias rubens. Circumoral nerve ring (ectoneural) (a);Radial nerve cord (ectoneural) (b, transverse; c, longitudinal); Marginal nerve (d); Pyloric andcardiac stomach (e, f); Pyloric caecae (g); Coelomic epithelium (h).

ArCTP mRNA expression in Asterias rubens. Circumoral nerve ring (a); Radial nerve cord(transverse) (b); Radial nerve cord (longitudinal) (c); Pyloric stomach (d); Cardiac stomach (e);Pyloric caecae (f); Coelomic epithelium (g)

Discovery and localisation of the expression of calcitonin-type and CRH-type neuropeptide precursors in an echinoderm

Weigang Cai, Michaela Egertová, Yusef Badi, Dean Semmens, Maurice R. ElphickSchool of Biological & Chemical Sciences, Queen Mary University of London

Asterias rubens CRH-type precursor (ArCRHP). Predicted signal peptide; putative CRH-typepeptide; C-terminal glycine (G) residue, putative substrate for amidation; putative dibasic cleavagesite (* = stop codon).

Asterias rubens calcitonin-type precursor (ArCTP). Predicted signal peptide; putative CT-typepeptide; C-terminal glycine (G) residue, putative substrate for amidation; putative dibasic cleavagesites (* = stop codon).

Alignment of ArCT with other calcitonin-type peptides

Localisation of:

ArCTP mRNA

METHODS• ArCTP and ArCRHP were identified using A. rubens neural transcriptome sequence data.• cDNAs encoding ArCTP and ArCRHP were cloned and sequenced from A. rubens radial nerve cDNA.• Starfish (A. rubens) were fixed with 4% paraformaldehyde and decalcified inMorse’s solution.• Fixed animals (arms, disk) were embedded in paraffin wax and sectioned using a microtome.• DIG-labelled probes complementary to ArCTP and ArCRHP were used for mRNA in situ hybridization.

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CONCLUSIONS• Cells expressing ArCTP in ectoneural and hyponeural regions of the radial nerve cords andcircumoral nerve ring, cardiac and pyloric stomachs, coelomic epithelium and pyloric caecae.

• Cells expressing ArCRHP in ectoneural region of the radial nerve cords and circumoral nerve ring,marginal nerves, coelomic epithelium, cardiac and pyloric stomachs and pyloric caecae.

• This is the first study of the expression of calcitonin- and CRH-type precursors in an echinoderm.• These data provide a basis for investigation of the physiological roles of calcitonin-type and CRH-type neuropeptides in starfish.

STARFISH ANATOMY

Acknowledgements

INTRODUCTION•Neuropeptides are neuronal signalling molecules that have been characterised in vertebratesand some invertebrate species (e.g the protostomian invertebrates Drosophila and C. elegans).•Studies on deuterostomian invertebrates such as echinoderms (e.g. starfish) can bridge the“evolutionary gap” between protostomian invertebrates and the vertebrates.•Calcitonin and Corticotropin-Releasing- Hormone (CRH) have well known physiological roles invertebrates, but little is known about the functions of these hormones in invertebrates•Here we used mRNA in situ hybridization to investigate the expression patterns of calcitonin-type and CRH-type precursors in the starfish Asterias rubens.

Chordata

Echinodermata

Mollusca

Annelida

Arthropoda

Nematoda

ANIMAL PHYLOGENY

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Email: w.cai@qmul.ac.uk

Calcitonin-type precursor CRH-type precursor

Alignment of ArCRH with other CRH-type peptides

ArCRHP mRNA expression patternArCTP mRNA expression pattern

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d e f g e f h

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ArCRHP mRNA

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amide

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