Peptide fragments induce a more rapid immune response than intact proteins in earthworms

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.

The lysosomes of earthworm chloragocytes: biochemical and morphological characterization

Nine latent and sedimentable acid hydrolases have been detected in the homogenates of earthworm chloragocytes. Their full activity was revealed by treatment with Triton X-100, a Waring blender treatment, freezing and thawing, hypotonic media or incubation at pH 5 and 25 degrees C. Solubilization paralleled the activation of the enzymes. Together with kinetic studies, these results indicate that the acid hydrolases of the chloragocytes are inside typical lysosome-like particles whose membrane is impermeable to their substrates. It could be shown by density equilibration centrifugation that the lysosomes of those cells constitute a heterogeneous population of subcellular particles distinct from the chloragosomes. Moreover, their digestive function has been directly demonstrated by the capture and degradation of serum albumin. The lysosomes of the chloragocytes have been clearly identified as polyvesicular bodies by electron microscopic analysis of the fractions obtained by density equilibration centrifugation and by examination of the whole tissue, as such or after endocytosis of serum albumin or ferritin. Finally, our results do not support a possible relationship between the lysosomes and the chloragosomes of the chloragocytes.

Antimicrobial defense of the earthworm

Discrimination of self and nonself is one of the features of all animal species but the ways of elimination of nonself are different. Defense strategies of invertebrates, which lack antibodies and lymphocytes, are based on innate defense mechanisms. The study of such, undoubtedly less complex, defense mechanisms in invertebrates may shed a new light on the more sophisticated immunity of vertebrates. The main aim of this review is to show on one experimental model--an oligochaete annelid--cellular and humoral defense pathways protecting against microbial infection.

Characterization of the limited specificity of antigen recognition in earthworms

Parenteral administration of foreign proteins results in earthworms in significantly increased levels of the antigen-binding protein (ABP). The earthworms (Lumbricus terrestris and Eisenia foetida; Oligochaeta, Annelida) were stimulated with different proteins and the ABP response was followed with an anti-ABP monoclonal antibody and in ligand assay with biotin conjugates of all proteins used for stimulation. ABP levels are increased after the stimulation with different proteins irrespective of the size and extent of glycosylation. Molar mass of the ABP molecules was always the same, 56 kDa in L. terrestris and 60 kDa in E. foetida. The level of the specificity is considerably lower in comparison with immunoglobulins since ABP reacts not only with the protein used for stimulation but also, though to lesser extent, with related proteins.