Sites of expression of mRNA for lysenin, a protein isolated from the coelomic fluid of the earthworm Eisenia foetida

Annelid Coelomic Fluid Proteins

The coelomic cavity is part of the main body plan of annelids. This fluid filled space takes up a considerable volume of the body and serves as an important site of exchange of both metabolites and proteins. In addition to low molecular substances such as amino acids and glucose and lactate, the coelomic fluid contains different proteins that can arise through release from adjacent tissues (intestine) or from secretion by coelomic cells. In this chapter, we will review the current knowledge about the proteins in the annelid coelomic fluid. Given the number of more than 20,000 extant annelid species, existing studies are confined to a relatively few species. Most studies on the oligochaetes are confined to the earthworms-clearly because of their important role in soil biology. In the polychaetes (which might represent a paraphyletic group) on the other hand, studies have focused on a few species of the Nereidid family. The proteins present in the coelomic fluid serve different functions and these have been studied in different taxonomic groups. In oligochaetes, proteins involved antibacterial defense such as lysenin and fetidin have received much attention in past and ongoing studies. In polychaetes, in contrast, proteins involved in vitellogenesis and reproduction, and the vitellogenic function of coelomic cells have been investigated in more detail. The metal binding metallothioneins as well as antimicrobial peptides, have been investigated in both oligochaetes and polychaetes. In the light of the literature available, this review will focus on lipoproteins, especially vitellogenin, and proteins involved in defense reactions. Other annelid groups such as the Pogonophora, Echiura, and Sipuncula (now considered polychaetes), have not received much attention and therefore, this overview is far from being complete.

Identification of novel lumbricin homologues in Eisenia andrei earthworms

Lumbricin and its orthologue antimicrobial peptides were typically isolated from annelids. In this report, mRNA for lumbricin and -serendipitously- a novel lumbricin-related mRNA sequence were identified in Eisenia andrei earthworms. The determined mRNA sequences of E. andrei lumbricin and lumbricin-related peptide consist of 477 and 575 nucleotides. The precursors of proline-rich E. andrei lumbricin and the related peptide contain 63 and 59 amino acids, respectively. Phylogenetic analysis indicated close relationship with other annelid lumbricins. Highest expression of both mRNAs appeared in the proximal part of the intestine (pharynx, gizzard), while other tested organs had moderate (body wall, midgut, ovary, metanephridium, seminal vesicles, ventral nerve cord) or low (coelomocytes) levels. During ontogenesis their expression revealed continuous increase in embryos. Following 48 h of in vivo Gram-positive bacteria challenge both mRNAs were significantly elevated in coelomocytes, while Gram-negative bacteria or zymosan stimulation had no detectable effects.

Environmental pollutants, pathogens and immune system in earthworms

Earthworms also known as farmer's friends are natural tillers of soil. They belong to Phylum Annelida and class Oligochaeta. Acid soils with organic matter and surface humus maintain the largest fauna of worms and earthworms. Due to their habitat in soil, they are constantly exposed to microbes and pollution generated by anthropogenic sources. Studies have revealed that damage of the immune system of earthworms can lead to alterations of both morphological and cellular characteristics of worms, activation of signalling pathways and can strongly influence their survival. Therefore, the understanding of the robust immune system in earthworms has become very important from the point of view of understanding its role in combating pathogens and pollutants and its role in indicating the soil pollution. In this article, we have outlined the (i) components of the immune system and (ii) their function of immunological responses on exposure to pollutants and pathogens. This study finds importance from the point of view of ecotoxicology and monitoring of earthworm health and exploring the scope of earthworm immune system components as biomarkers of pollutants and environmental toxicity. The future scope of this review remains in understanding the earthworm immunobiology and indicating strong biomarkers for pollution.

Protective role of metallothionein during regeneration in Eisenia andrei exposed to cadmium

Lumbricid earthworms are often exposed to simultaneous action of various environmental stressors like soil contamination, temperature fluctuation or predators' attacks, which may induce extrusion of coelomocyte-containing coelomic fluid or loss of tail segments. If the injuries are not lethal, renewal of the immune-competent cells and soluble components of coelomic fluid and/or the regeneration of tail segments occurs. The aim of our investigations was to test the hypothesis that exposure of adult earthworms Eisenia andrei to cadmium-polluted soil at room temperature (RT) and/or low temperature (6°C) have adverse effects on restoration of experimentally depleted coelomocytes or on regeneration of amputated posterior segments. Intact control earthworms and their experimental counterparts subjected to electrostimulation-induced coelomocyte depletion or surgical amputation of posterior segments were maintained either in control soil or in soil spiked with cadmium chloride (500mg/kg air-dried soil) at RT or 6°C. Four weeks after the beginning of experiments, cadmium accumulation in earthworm bodies was significantly lower at 6°C than at room temperature. The numbers of restored cells and fluorophore contents were hardly affected by temperature or cadmium. However, cocoon production was reduced by cadmium and completely abolished at 6°C and regeneration of amputated posterior segments was inhibited in cold but was enhanced by cadmium exposure at RT. Independently on the temperature, the 4-week cadmium exposure of adult earthworms was connected with significantly upregulated expression of Cd-metallothionein (but not of catalase, lysenin and phytochelatin) in coelomocytes.

Lysenin family proteins in earthworm coelomocytes - Comparative approach

Sphingomyelin-binding proteins of the lysenin family were originally identified in earthworms belonging to the genus Eisenia comprised of at least two distinct species, E. andrei and E. fetida, until recently considered subspecies or morphotypes of E. foetida (sic). In the present study the presence of lysenin and lysenin-related protein 2 (LRP-2, known also as fetidin) was detected in coelomocytes retrieved from all investigated adult specimens of E. andrei, and E. fetida. They were accompanied by LRP-3 and LRP-1 in some specimens of E. andrei and E. fetida, respectively. Lysenins were not observed in a third composting lumbricid species, Dendrobaena veneta, which served as a convenient negative reference for techniques and procedures used in the study. The pore-forming potential of soluble and cellular fractions of coelomic fluid was studied towards sheep red blood cells and sphingomyelin-rich liposomes. After experimental depletion the potential was restored in parallel with restoration of chloragocyte-derived eleocytes in both E. andrei and E. fetida.

A new earthworm cellulase and its possible role in the innate immunity

A new endogenous cellulase (Ean-EG) from the earthworm, Eisenia andrei and its expression pattern are demonstrated. Based on a deduced amino acid sequence, the open reading frame (ORF) of Ean-EG consisted of 1368 bps corresponding to a polypeptide of 456 amino acid residues in which is contained the conserved region specific to GHF9 that has the essential amino acid residues for enzyme activity. In multiple alignments and phylogenetic analysis, the deduced amino acid sequence of Ean- EG showed the highest sequence similarity (about 79%) to that of an annelid (Pheretima hilgendorfi) and could be clustered together with other GHF9 cellulases, indicating that Ean-EG could be categorized as a member of the GHF9 to which most animal cellulases belong. The histological expression pattern of Ean-EG mRNA using in situ hybridization revealed that the most distinct expression was observed in epithelial cells with positive hybridization signal in epidermis, chloragogen tissue cells, coelomic cell-aggregate, and even blood vessel, which could strongly support the fact that at least in the earthworm, Eisenia andrei, cellulase function must not be limited to digestive process but be possibly extended to the innate immunity.

Cold-stress induced formation of calcium and phosphorous rich chloragocyte granules (chloragosomes) in the earthworm Eisenia fetida

The cytochemical and functional characteristics of chloragocytes of both 'control' and cold-stressed Eisenia fetida were examined. Flow cytometry revealed the heterogeneity of chloragocytes: the first group was characterized by low, the second one by high acid phosphatase (AcP) content. In 'control' animals the former, in cold-stressed ones the latter type were the dominant form. The elevated AcP-activity correlated with the accumulation of autophagic vacuoles (AVs) in chloragocytes. Both AVs and all small chloragosomes showed high AcP activity, while most of the large chloragosomes did not display any. Most 'control' granules (0.75-1.25 μm) contained high amounts of Ca and P, with less and variable quantities of S, Cl, K, Fe and Zn. Small chloragosomes with low Ca and P concentrations were seldom found. In cold-stressed animals the number of small granules (0.25-0.75 μm) increased up to 40% of total population. Their Ca and P contents were significantly lower; S and Fe concentrations were higher than those of large chloragosomes (1.0-1.5 μm). Our results prove that the formation and elemental composition of chloragosomes can be influenced by environmental stressors and suggest that the mature chloragosomes are tertiary lysosomes and their formation is coupled to autophagocytosis.

Gene expression analysis of 4 biomarker candidates in Eisenia fetida exposed to an environmental metallic trace elements gradient: a microcosm study

Past activities of 2 smelters (Metaleurop Nord and Nyrstar) led to the accumulation of high amounts of Metal Trace Elements (TEs) in top soils of the Noyelles-Godault/Auby area, Northern France. Earthworms were exposed to polluted soils collected in this area to study and better understand the physiological changes, the mechanisms of acclimation, and detoxification resulting from TE exposure. Previously we have cloned and transcriptionally characterized potential biomarkers from immune cells of the ecotoxicologically important earthworm species Eisenia fetida exposed in vivo to TE-spiked standard soils. In the present study, analysis of expression kinetics of four candidate indicator genes (Cadmium-metallothionein, coactosin like protein, phytochelatin synthase and lysenin) was performed in E. fetida after microcosm exposures to natural soils exhibiting an environmental cadmium (Cd) gradient in a kinetic manner. TE body burdens were also measured. This microcosm study provided insights into: (1) the ability of the 4 tested genes to serve as expression biomarkers, (2) detoxification processes through the expression analysis of selected genes, and (3) influence of land uses on the response of potential biomarkers (gene expression or TE uptake).

Bi-stability, hysteresis, and memory of voltage-gated lysenin channels

Lysenin, a 297 amino acid pore-forming protein extracted from the coelomic fluid of the earthworm E. foetida, inserts constitutively open large conductance channels in natural and artificial lipid membranes containing sphingomyelin. The inserted channels show voltage regulation and slowly close at positive applied voltages. We report on the consequences of slow voltage-induced gating of lysenin channels inserted into a planar Bilayer Lipid Membrane (BLM), and demonstrate that these pore-forming proteins constitute memory elements that manifest gating bi-stability in response to variable external voltages. The hysteresis in macroscopic currents dynamically changes when the time scale of the voltage variation is smaller or comparable to the characteristic conformational equilibration time, and unexpectedly persists for extremely slow-changing external voltage stimuli. The assay performed on a single lysenin channel reveals that hysteresis is a fundamental feature of the individual channel unit and an intrinsic component of the gating mechanism. The investigation conducted at different temperatures reveals a thermally stable reopening process, suggesting that major changes in the energy landscape and kinetics diagram accompany the conformational transitions of the channels. Our work offers new insights on the dynamics of pore-forming proteins and provides an understanding of how channel proteins may form an immediate record of the molecular history which then determines their future response to various stimuli. Such new functionalities may uncover a link between molecular events and macroscopic processing and transmission of information in cells, and may lead to applications such as high density biologically-compatible memories and learning networks.

Transcriptomic underpinning of toxicant-mediated physiological function alterations in three terrestrial invertebrate taxa: a review

Diverse anthropogenic activities often lead to the accumulation of inorganic and organic residues in topsoils. Biota living in close contact with contaminated soils may experience stress at different levels of biological organisation throughout the continuum from the molecular-genetic to ecological and community levels. To date, the relationship between changes at the molecular (mRNA expression) and biochemical/physiological levels evoked by exposures to chemical compounds has been partially established in a limited number of terrestrial invertebrate species. Recently, the advent of a family of transcriptomic tools (e.g. Real-time PCR, Subtractive Suppressive Hybridization, Expressed Sequence Tag sequencing, pyro-sequencing technologies, Microarray chips), together with supporting informatic and statistical procedures, have permitted the robust analyses of global gene expression changes within an ecotoxicological context. This review focuses on how transcriptomics is enlightening our understanding of the molecular-genetic responses of three contrasting terrestrial macroinvertebrate taxa (nematodes, earthworms, and springtails) to inorganics, organics, and agrochemicals.

Metallic trace element body burdens and gene expression analysis of biomarker candidates in Eisenia fetida, using an "exposure/depuration" experimental scheme with field soils

Smelting plant activities lead to the accumulation of Metal Trace Elements (MTEs) in soils. The presence of high concentrations of MTEs can generate an environmental stress likely to affect macroinvertebrates living in close soil contact such as the Annelida Oligochaeta. Eisenia fetida, an ecotoxicologically important test species, was successively exposed to two field soils: (1) a highly contaminated agricultural topsoil collected near the former smelter Metaleurop Nord (Noyelles-Godault, France) which contaminated surrounding soils by its atmospheric emissions [exposure phase], and then (2) a slightly contaminated topsoil from an urban garden located in the conurbation of Lille (Wambrechies) [depuration phase]. Two analyses were performed during each phase. Firstly, the gene expression levels of four biomarker candidates identified in previous studies were analyzed in E. fetida coelomocytes. These candidates are Cd-metallothionein, phytochelatin synthase, coactosin-like protein and lysenin. Secondly, the body burdens of the following elements Cd, Pb, Zn, Cu, Fe, Ca, and P were measured. Moreover, both analyses were also performed in Lumbricus rubellus, an Annelid species collected from the two tested soil-originating sites. Analysis of gene expression and MTE body burdens in both species are discussed to: (1) evaluate expression biomarkers; (2) gain insight the detoxification processes and the long-term response to a metallic stress and (3) compare the responses observed in a test species (E. fetida) with the responses of a field species (L. rubellus).

Identification and expression profile of gene transcripts differentially expressed during metallic exposure in Eisenia fetida coelomocytes

The aim of this work was to identify in Eisenia fetida genes whose expression are regulated following exposure to a complex mixture of metallic trace elements (MTE) representative of a highly polluted smelter soil. Suppression subtractive hybridization (SSH) was used to construct cDNA libraries enriched in up- or down-regulated transcripts in the immune-circulating cells of the coelomic cavities, namely coelomocytes, from worms exposed to metallic pollution. Among 1536 SSH-derived cDNA clones sequenced, we identified 764 unique ESTs of which we selected 18 candidates on the basis of their redundancy. These selected candidates were subjected to a two-step validation procedure based on the study of their expression level by real-time PCR. The first step consisted in measuring the expression of the 18 candidates in worms exposed to artificial contaminated soil. The second step consisted in measuring the expression in animals exposed to a "naturally" contaminated soil sampled close to a smelter. Both steps allowed us to highlight 3 candidates that are strongly induced in worms exposed to a smelter polluted soil. These candidates are: the well-known MTE-induced Cd-metallothionein and 2 original biomarkers, lysenin, and a transcript, which cloning of the complete coding sequence identified as the coactosin-like protein.

Morphology and ultrastructure of the earthworm Dendrobaena veneta (Lumbricidae) coelomocytes

Microscope techniques, light microscope (LM), transmission electron microscope (TEM), scanning electron microscope (SEM) were employed to describe and classify coelomocytes of the oligochaete Dendrobaena veneta. Three main cell types were distinguished in the coelomic fluid: eleocytes, amoebocytes and granulocytes. Eleocytes are large, oval cells containing characteristic granules called chloragosomes. Amoebocytes are most numerous coelomocytes and have been divided into two types (I and II). Both amoebocytes of the types I and II often form aggregations of a few to about a dozen cells. Granulocytes are oval cells with spherical nuclei and cytoplasm containing polymorphic, electron dense granules. Contrary to the amoebocytes, the granulocytes do not form aggregations. Morphology and ultrastructure of coelomocytes are presented on micrographs: similarities and differences are compared to coelomocytes of related species.

Biology of Lysenin, a Protein in the Coelomic Fluid of the Earthworm Eisenia foetida

Lysenin is a protein of 33?kDa in the coelomic fluid (CF) of the earthworm Eisenia foetida. It differs from other biologically active proteins, such as fetidins, eiseniapore, and coelomic cytolytic factor (CCF-1), that have been found in Eisenia foetida, in terms of both its biochemical and its biological characteristics. The large coelomocytes and free chloragocytes in the typhlosole of Eisenia foetida appear to be the cells that produce lysenin since the mRNA for lysenin and immunoreactive lysenin have been found in these cells. Lysenin binds specifically to sphingomyelin (SM) but not to other phospholipids in cell membranes. After binding to the cell membranes of target cells, lysenin forms oligomers in an SM-dependent manner, with subsequent formation of pores with a hydrodynamic diameter of approximately 3?nm. The biochemical interactions between lysenin and SM in cell membranes are responsible for the pharmacological activities of lysenin and of CF that contains lysenin in vertebrates, such as hemolysis, cytotoxicity, and contraction of smooth muscle in vitro and vasodepressor activity and lethality in vivo. When incubated with SM-liposomes, CF and lysenin lost some or all of their activity, an observation that suggests that SM might be involved in the induction of the various activities of lysenin and CF. However, in general, lysenin is neither cytotoxic nor lethal to invertebrates. An attempt has been made to explain the differences in the responses to lysenin and CF between vertebrates and invertebrates in terms of the presence or absence of SM in the various animals. Among Protostomia, SM is absent in Lophotrochozoa, with the exception of some molluscan species, but it is present in Ecdysozoa, with the exception of Nematomorpha and flies. Among Deuterostomia, Echinodermata and Hemichordata lack SM but SM is found in Chordata. Thus, the difference in terms of the response to lysenin between invertebrates and vertebrates cannot be fully explained by reference to the presence or absence of SM in the organism. Lysenin and its antiserum have made it possible to localize SM in the cell membranes. They should be a useful tool for studies of membrane physiology and the role of SM.

Mass spectrometric analyses of CL(39), CL(41) and H(1), H(2), H(3) confirm identity with fetidin and lysenin produced by earthworm leukocytes

Antibacterial proteins realize effective immunological mechanisms against invading pathogens. Some of them exert hemolytic and agglutinating properties. Here, we analyzed two hemolysins isolated from cell lysate (CL(39) and CL(41)) and three hemolytic proteins isolated from coelomic fluid (H(1), H(2) and H(3)) of the annelid Eisenia fetida using mass spectrometry and bioinformatics. We demonstrated the identity of CL(39,41) with fetidin and lysenin; these have been described earlier. H(1-3) share sequence components with fetidin but they seem to be glycosylated as shown for H(1). The results help to resolve a long debate concerning nomenclature and identity of these hemolytic proteins. They support: (1). the concept that the hemolytic proteins originate from chloragocytes; (2). their origin to some extent from large coelomocytes; and (3). the view that they are secreted into CF.

Lysenin, a unique sphingomyelin-binding protein

Sphingomyelin plays complex structural and signaling functions in the plasma membrane. Of special interest is that hydrolysis of sphingomyelin to ceramide can modulate dynamics of membrane rafts, which serve as signaling platforms for various receptors. This review is focused on a recently discovered sphingomyelin-binding protein, lysenin, which can be used as a unique probe to trace distribution and turnover of sphingomyelin in cellular membranes. We analyze the primary and secondary structures of lysenin with respect to its interaction with the plasma membrane. The specificity of lysenin binding to sphingomyelin, revealed by both biochemical and cytochemical approaches, is discussed.