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Mass spectrometry imaging reveals new biological roles for choline esters and Tyrian purple precursors in muricid molluscs.

Rudd D, Ronci M, Johnston MR, Guinan T, Voelcker NH, Benkendorff K - Sci Rep (2015)

Bottom Line: But during egg-laying, murexine was transferred to the capsule gland, and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation.Murexine was found to tranquilise the larvae and may relax the reproductive tract.This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Bedford Park, SA 5042, Australia.

ABSTRACT
Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such example is the association between choline esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing choline ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland, and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.

No MeSH data available.


Related in: MedlinePlus

DIOS-MSI maps of secondary metabolites imprinted onto pSi from female D. orbita across the reproductive cycle, in positive ion mode at 100 μm spatial resolution.(Pre) representative female section sampled 30 days prior to the breeding season. (During) female section sampled during encapsulation. (Post) representative female section sampled 14 days post encapsulation. Maps are compared to (A) histological sections and (B) scanned tissue sections on pSi prior to removal. Tissue regions include (hg) medial hypobranchial gland and (cg) capsule gland. Ion maps m/z 340 corresponds to tyrindoxyl hydrogen sulfate [M+H]+, m/z 256 to tyrindoleninone [M+H]+, m/z 421 to Tyrian purple [M+H]+, and m/z 224 to murexine [M]+. Scale bar set to 2 mm.
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f2: DIOS-MSI maps of secondary metabolites imprinted onto pSi from female D. orbita across the reproductive cycle, in positive ion mode at 100 μm spatial resolution.(Pre) representative female section sampled 30 days prior to the breeding season. (During) female section sampled during encapsulation. (Post) representative female section sampled 14 days post encapsulation. Maps are compared to (A) histological sections and (B) scanned tissue sections on pSi prior to removal. Tissue regions include (hg) medial hypobranchial gland and (cg) capsule gland. Ion maps m/z 340 corresponds to tyrindoxyl hydrogen sulfate [M+H]+, m/z 256 to tyrindoleninone [M+H]+, m/z 421 to Tyrian purple [M+H]+, and m/z 224 to murexine [M]+. Scale bar set to 2 mm.

Mentions: To explore the biological roles of muricid choline esters and brominted indoles using DIOS-MSI in the context of egg laying and maternal investment, established spatial patterns based on previous histochemical staining37 were used as a basis to track changes in secondary metabolite distribution at different phases of the reproductive cycle. The reliable performance of pSi in detecting the range of secondary metabolites was validated using organic extracts prepared from the same population of breeding individuals. Extracts were analysed by liquid chromatography mass spectrometry (LC-MS/MS) according to established procedures in our laboratory353638 (Supplementary Figs 1 & 2), and used as a comparison for those detected in DIOS-MS and MSI (Figs 2 and 3). The capacity for pSi to desorb and ionise brominated indoles from the tissue samples was confirmed by the detection of isotopic patterns in MS/MS analysis consistent with the crude extracts analysed by LC-MS (Supplementary Figs 2 and 3) and with purified compounds and synthetic 6 bromoisatin and 6,6′-dibromoindigo spotted directly onto the pSi surface39. DIOS-MS takes advantage of the van der Waals interactions and hydrogen bonding between the analyte containing the secondary metabolites and the silanised pSi surface. Attractive properties combined with high porosity (~600 m2 cm−3) allow pSi to selectively extract small molecules in a sponge-like manner40. Consistent with our previous studies2539, brominated indoles across a broad range of polarities in the low mass region from m/z 256–421 (Fig. 2 and Supplementary Fig. 2), showed affinity to the pSi surface.


Mass spectrometry imaging reveals new biological roles for choline esters and Tyrian purple precursors in muricid molluscs.

Rudd D, Ronci M, Johnston MR, Guinan T, Voelcker NH, Benkendorff K - Sci Rep (2015)

DIOS-MSI maps of secondary metabolites imprinted onto pSi from female D. orbita across the reproductive cycle, in positive ion mode at 100 μm spatial resolution.(Pre) representative female section sampled 30 days prior to the breeding season. (During) female section sampled during encapsulation. (Post) representative female section sampled 14 days post encapsulation. Maps are compared to (A) histological sections and (B) scanned tissue sections on pSi prior to removal. Tissue regions include (hg) medial hypobranchial gland and (cg) capsule gland. Ion maps m/z 340 corresponds to tyrindoxyl hydrogen sulfate [M+H]+, m/z 256 to tyrindoleninone [M+H]+, m/z 421 to Tyrian purple [M+H]+, and m/z 224 to murexine [M]+. Scale bar set to 2 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555103&req=5

f2: DIOS-MSI maps of secondary metabolites imprinted onto pSi from female D. orbita across the reproductive cycle, in positive ion mode at 100 μm spatial resolution.(Pre) representative female section sampled 30 days prior to the breeding season. (During) female section sampled during encapsulation. (Post) representative female section sampled 14 days post encapsulation. Maps are compared to (A) histological sections and (B) scanned tissue sections on pSi prior to removal. Tissue regions include (hg) medial hypobranchial gland and (cg) capsule gland. Ion maps m/z 340 corresponds to tyrindoxyl hydrogen sulfate [M+H]+, m/z 256 to tyrindoleninone [M+H]+, m/z 421 to Tyrian purple [M+H]+, and m/z 224 to murexine [M]+. Scale bar set to 2 mm.
Mentions: To explore the biological roles of muricid choline esters and brominted indoles using DIOS-MSI in the context of egg laying and maternal investment, established spatial patterns based on previous histochemical staining37 were used as a basis to track changes in secondary metabolite distribution at different phases of the reproductive cycle. The reliable performance of pSi in detecting the range of secondary metabolites was validated using organic extracts prepared from the same population of breeding individuals. Extracts were analysed by liquid chromatography mass spectrometry (LC-MS/MS) according to established procedures in our laboratory353638 (Supplementary Figs 1 & 2), and used as a comparison for those detected in DIOS-MS and MSI (Figs 2 and 3). The capacity for pSi to desorb and ionise brominated indoles from the tissue samples was confirmed by the detection of isotopic patterns in MS/MS analysis consistent with the crude extracts analysed by LC-MS (Supplementary Figs 2 and 3) and with purified compounds and synthetic 6 bromoisatin and 6,6′-dibromoindigo spotted directly onto the pSi surface39. DIOS-MS takes advantage of the van der Waals interactions and hydrogen bonding between the analyte containing the secondary metabolites and the silanised pSi surface. Attractive properties combined with high porosity (~600 m2 cm−3) allow pSi to selectively extract small molecules in a sponge-like manner40. Consistent with our previous studies2539, brominated indoles across a broad range of polarities in the low mass region from m/z 256–421 (Fig. 2 and Supplementary Fig. 2), showed affinity to the pSi surface.

Bottom Line: But during egg-laying, murexine was transferred to the capsule gland, and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation.Murexine was found to tranquilise the larvae and may relax the reproductive tract.This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Bedford Park, SA 5042, Australia.

ABSTRACT
Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such example is the association between choline esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing choline ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland, and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.

No MeSH data available.


Related in: MedlinePlus