[Genital system of the Aeolosomatidae with phylogenetically primitive organization traits for oligochaetes].
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Animal toxins are not to be understood as substances of random occurrence; they are of great importance in ecology. The venom-secreting organs have developed in a wide variety of ways and serve either as an offensive weapon or for protection against enemies. Accordingly, we may distinguish between actively venemous and passively venemous animals. There are other animals that are toxic rather by chance and due to extraneous factors; these we may call poisonous animals. Research into animal toxins is important from both the chemical and the biological points of view. In addition to basic knowledge, we may hope for interesting phylogenetic results from such research.
Fast-acting muscle of the sandworm, Nereis virens, contains one soluble calcium-binding protein having a molecular weight close to 17 000 and occurring in the muscle at a concentration of approximately 0.1 mM. The protein binds two Ca2+ at equivalent sites with dissociation constant Kd = 6.4 X 10(-7) M. Its N-terminal amino acid is blocked by an N-acetyl group whereas glycine is the C-terminal residue. The comparison of the tryptic peptide map of this protein with those of the soluble calcium-binding protein from crayfish muscle, bovine brain calmodulin and rabbit skeletal muscle troponin C suggests that all of these proteins are homologous. Sandworm calcium-binding protein therefore belongs to the so-called cytosolic calcium EF-hand family. This protein is presumably the functional counterpart of vertebrate parvalbumin acting as soluble relaxing factor.
Our interest in detecting genotoxic exposure in earthworms led us to isolate high quality DNA from the Eisenia fetida species. For that, we compared a modification of the conventional phenol-chloroform extraction procedure, usually referred to as the Maniatis procedure, to two commercially available kits reportedly eliminating multiple partitions in phenol and chloroform, namely the Qiagen and Nucleon protocols. From the 260 nm optical density values, the commercial kits extracts hinted toward higher DNA recovery with those procedures. However, the 260/280 nm ratios indicated that the quality of the DNA isolated with the modified Maniatis procedure was purer than that isolated with the commercial kits, the latter being most probably contaminated by proteins and/or RNA. The Maniatis procedure was slightly modified by the introduction of a potassium acetate step for protein precipitation and by shortening the proteinase K treatment from 12-18 h to only 2 h. The higher quality of the DNA isolated by phenol-chloroform extraction was confirmed by quantification with the fluorescent 3,5-diaminobenzoic acid assay. Preliminary results suggest that the modified Maniatis procedure herein described is not only applicable for DNA adducts studies using 32P-postlabelling techniques but is also suitable for DNA extraction from other earthworm species such as Lumbricus terrestris.
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The 2-deoxyglucose (2-DG) autoradiographic technique, in conjunction with 3H-labelled 2-DG and glutaraldehyde fixation, was applied to the isolated ganglia of the leech and the snail in order to analyse its potential use for the understanding of energy utilization in these simple nervous systems. Approximately 50% of the label is retained in these tissues after histological processing, and the method can be satisfactorily applied at the subcellular level. In both species most neurons progressively accumulate radioactivity over 15 min-1 h, although to different extents. In the leech the glial cells showed greater uptake than the neurons. Paired homologous neurons in contralateral buccal ganglia of the snail were equally labelled. In all structures studied by electron-microscope autoradiography the label was positively associated with glycogen. Freshly extracted glycogen from ganglia previously exposed to 2-DG was significantly labelled (2-10% of total radioactivity in the ganglia); thus the glutaraldehyde fixation did not appear responsible for artifactual binding of the label. The significance of the glycogen labelling and the potential of the technique for metabolic mapping in these nervous systems are discussed.
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