Localisation of transcripts encoding SALMFamide precursors in larvae of the starfish Asterias rubens (Linnaeus, 1758) 1,2 Mayorova ,
2 Zandawala ,
2 Rowe ,
2 M.Egertová ,
2 Elphick
T. M. M.L. M.R. 1 – Institute of Developmental Biology RAS, Moscow, Russia; 2 – School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
[email protected];
[email protected] INTRODUCTION. SALMFamides are a family of neuropeptides that act as muscle relaxants in echinoderms. SALMFamides were first discovered in the starfish Asterias rubens, with two related peptides identified – S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide). In A. rubens brachiolaria larvae, S1brachiolaria dorsal ciliary band like immunoreactivity is present in two groups RESULTS of cells extending along the dorsal ciliary S1 precursor expression band (see photo from Moss et al.,1994). 50µm Nothing is known about the physiological roles of SALMFamides in echinoderm larvae. Recently, analysis of A. rubens neural transcriptome sequence data has revealed that S1 and S2 are derived from different precursor proteins (Semmens et al., in prep), providing new opportunities to investigate the expression and physiological roles of SALMFamides in starfish larvae. AIMS AND METHODS: • To investigate the expression patterns of the S1- and S2precursors during the larval development of A. rubens using whole-mount mRNA in situ hybridisation (ISH). • To test the effects on larvae of a “cocktail” seven SALMFamides derived from the S1 precursor. Experiments were performed using A. rubens larvae collected at the White Sea Biostation in Russia.
Brachiolariae have two groups of cells expressing the S1 precursor.
30µm
Dorsal view Lateral view
S2 precursor expression The first cells expressing the S2 precursor develop at the early bipinnaria stage.
dorsal view
bipinnaria
brachiolaria
200µm
dorsal ciliary band
* **
brachiolar arms
*
* *
lateral view
Treatment with S1 precursor SALMFamide cocktail Brachiolariae fixed with PFA after SALMFamide treatment without Mg anesthetization -6 10 M
Control
-7 10 M
-8 10 M
-9 10 M
500µm
100µm
-9 10 M
-8 10 M
-7 10 M
-6 10 M
Control
Brachiolariae fixed after SALMFamide treatment without anesthetization; Phalloidin staining; note the shape of the oesophagus
CONCLUSIONS. Cells expressing the SALMFamide precursors are located along the dorsal ciliary band and in the lateral ganglia, which are a part of the apical organ. The S2 precursor is also expressed in brachiolar arms. As in adult echinoderms, SALMFamides may act in the larvae as muscle relaxants.
ACKNOWLEDGEMENTS. We would like to thank Elizaveta Fofanova, Denis Nikishin, and Boris Osadchenko for the help with collection and processing of material. We are grateful to the staff of the Pertsov White Sea Biological station. The work was supported by EMBO grant № ASTF 168-2014 and Leverhulme Trust grant RPG-2013-351.
