Identification of new fluorophores in coelomic fluid of Eisenia andrei earthworms.

Jerzy Kruk,Barbara Płytycz,Michał Dziurka,Jacob Guy Bundy

doi:10.1371/journal.pone.0214757

Abstract

Coelomic fluid of Eisenia andrei contains a number of UV-fluorescent compounds. In the present study we have found that four of these compounds showed identical fluorescence excitation and emission maxima at 310 nm and 364 nm, respectively, suggesting they share the same chromophore. NMR and HR-MS spectroscopy of the most abundant fluorophore reavealed that its molecule is composed of two quinazoline-2,4-dione rings connected by spermine linker. This compound was earlier indentified in Eisenia andrei as SP-8203. Moreover, we have identified the structure of the two other fluorophores, one differing from SP-8203 by the absence of N-acetyl group, the compound not reported in any other organisms before, and the other already found in E. fetida and regarded as species specific. However, our results indicate that this metabolite is also present in E. andrei in significant amounts. The possible origin and function of these new metabolites is discussed.

Highlights

Similar lumbricid species occupying the same ecological niche, Eisenia andrei and E. fetida, can be phenotypically differentiated by metabolic profiling of tissue extracts and/ or coelomic fluid [1]
Fluorescence spectra of coelomic fluid of these species were for the first time used for taxonomic purposes by Albani et al [2], and E. andrei specific fluorophore was suggested as 4-methylumbelliferyl β-D-glucoronide (MUGlcU)
Specific fluorescence spectra with a peak of excitation at 310–320 nm and a peak of emission at 370–380 nm, were used by our group as one of taxonomic markers of E. andrei, and called the MUG, MUG-like, or the M fluorescence. During these studies the MUG/ MUG-like fluorescence spectra were detected in E. andrei and in a few of E. fetida earthworms [4,5,6] that inspired us for studies on hybridisation between laboratory joined inter-specific pairs of M-positive E. andrei with M-negative E. fetida

Summary

Introduction

Similar lumbricid species occupying the same ecological niche, Eisenia andrei and E. fetida, can be phenotypically differentiated by metabolic profiling of tissue extracts and/ or coelomic fluid [1]. Specific fluorescence spectra with a peak of excitation at 310–320 nm and a peak of emission at 370–380 nm, were used by our group as one of taxonomic markers of E. andrei, and called the MUG, MUG-like, or the M fluorescence. During these studies the MUG/ MUG-like fluorescence spectra were detected in E. andrei and in a few of E. fetida earthworms [4,5,6] that inspired us for studies on hybridisation between laboratory joined inter-specific pairs of M-positive E. andrei with M-negative E. fetida. The results revealed the existence of asymmetrical hybridization between these hermaphroditic species able to self-

Methods

Results

Conclusion