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At least 19 recordsLinked to original sources

PubMed2004

Biomechanical analysis of Oligochaeta crawling.

Hydrostatic skeletons, such as that of Oligochaeta and Hirudinea, allow the locomotion of animals with soft segmented bodies. In this paper crawling of Oligochaeta, and in particular that of earthworm (Lumbricus terrestris), is analyzed from a biomechanical point of view, starting from the experimental kinematic description of deformations coupled with a simple friction model. The analysis is able to predict crawling velocity with an error of about 15% with respect to the experimental measured values. Also muscular stress during locomotion is evaluated and found to be compatible with biological values.

Animals↗

PubMed2004

Nerve development, growth and differentiation during regeneration in Enchytraeus fragmentosus and Stylaria lacustris (Oligochaeta).

Enchytraeus fragmentosus (Enchytraeidae) and Stylaria lacustris (Naididae) are small terrestrial and limnetic oligochaetes that exclusively or seasonally reproduce by fragmentation and regeneration, respectively. We traced the neuronal development and differentiation during regeneration in order to gain information on the basic organization and evolution of the oligochaete nervous system. Subsequent to artificial amputation, the nervous systems have been stained with antibodies directed against acetylated alpha-tubulin. The staining was analyzed by indirect fluorescence in combination with confocal laser scanning microscopy. Both species show unique oligochaete neuronal regeneration patterns: (i) numerous fibers branch off from segmental nerves near the wound site and innervate the blastema; and (ii) the ventral cord is partly reestablished before the circumesophageal connectives develop. In the investigated 'Oligochaeta' the outgrowing fibers of the ventral nerve cord are soon bundled into at least two distinct connective pairs, which prolong into dorsal and ventral roots next to the mouth. Subsequent complete fusion of the doubled roots forms simple connectives. Thus, dorsal roots are not a unique feature for 'Polychaeta'. They occur as a transient structure in 'Oligochaeta' and might be part of the neuronal ground pattern of Annelida. The initially tetra or even pentaneuronal ventral nerve cord also differentiates into an unineuronal one by fusion.

Animals↗

PubMed2005

Bipolar head regeneration induced by artificial amputation in Enchytraeus japonensis (Annelida, Oligochaeta).

The Enchytraeida Oligochaeta Enchytraeus japonensis propagates asexually by spontaneous autotomy. Normally, each of the 5-10 fragments derived from a single worm regenerates a head anteriorly and a tail posteriorly. Occasionally, however, a head is formed posteriorly in addition to the normal anterior head, resulting in a bipolar worm. This phenomenon prompted us to conduct a series of experiments to clarify how the head and the tail are determined during regeneration in this species. The results showed that (1) bipolar head regeneration occurred only after artificial amputation, and not by spontaneous autotomy, (2) anesthesia before amputation raised the frequency of bipolar head regeneration, and (3) an extraordinarily high proportion of artificially amputated head fragments regenerated posterior heads. Close microscopic observation of body segments showed that each trunk segment has one specific autotomic position, while the head segments anterior to the VIIth segment do not. Only the most posterior segment VII in the head has an autotomic position. Examination just after amputation found that the artificial cutting plane did not correspond to the normal autotomic position in most cases. As time passed, however, the proportion of worms whose cutting planes corresponded to the autotomic position increased. It was suspected that the fragments autotomized after the artificial amputation (corrective autotomy). This post-amputation autotomy was probably inhibited by anesthesia. The rate at which amputated fragments did not autotomize corresponded roughly to the rate of bipolar regeneration. It was hypothesized then that the head regenerated posteriorly if a fragment was not amputated at the precise autotomic position from which it regenerated without succeeding in corrective autotomy.

Animals↗

PubMed1999

Resistance of Eisenia fetida (Oligochaeta) to cadmium after long-term exposure.

The reliance on earthworms as test organisms in risk assessment studies of polluted environments raises the question whether they can evolve resistance, e.g., by adaptation to specific toxicants. Protection criteria may be biased if sensitivity data from adapted populations are used. Increased resistance to the heavy metal cadmium has not yet been determined for terrestrial Oligochaeta. Eisenia fetida was exposed to a sublethal concentration of cadmium sulfate for more than 10 generations. Clitellate worms from this culture were used in experiments to determine the extent of possible tolerance for the heavy metal. Preexposed animals as well as worms with no previous history of exposure to cadmium were exposed to a control substrate without cadmium and also to two substrates with 600 and 1200 microg g-1 cadmium. Changes in biomass, cocoon production, and hatching success were monitored. The results obtained indicated that in both substrates in which cadmium was present the preexposed worms performed better than the unexposed worms with respect to growth rate but not reproductively. In the substrate without cadmium the preexposed worms exhibited signs of poisoning after a few weeks. Preexposed and unexposed worms were also exposed to concentrations of 1500 to 4000 microg g-1 cadmium sulfate in an artisol medium for a period of 2 weeks. The preexposed worms survived higher concentrations of cadmium than the unexposed group and some specimens from the unexposed group had a gross increase in body fluids. It is concluded that worms with a long-term history of exposure to the metal developed resistance to cadmium.

Animals↗

PubMed1987

Analysis and reconstruction of unusual obliquely striated fibres in Lumbriculids (Annelida, Oligochaeta).

The longitudinal muscle fibres of Lumbriculids (Annelida, Oligochaeta) have been studied by means of electron microscopy. These fibres are obliquely striated (flattened circomyarian) and possess Z-elements and sarcotubules which frequently cross the centre of the fibre connecting the cell surface on the opposite sides. The myosin filaments have, in cross-section, a rectangular profile with the long side parallel to the fibre surface; they look wavy (S-shaped) on the XZ plane, thus crossing the whole thickness of the sarcomere. The three-dimensional interpretation of the contractile apparatus was facilitated by the comparison of the micrographs from ad hoc sections of the three spatial planes with corresponding calculated "sections', obtained with a dynamic computer model. The real periodicity of the different contractile structures has been determined and the wavy shape of the thick filaments on the XZ plane has been demonstrated by indirect proofs: computed images in which rectangular filaments are parallel to the fibre axis cannot be made to yield a situation comparable with real images. Furthermore, the distances (centre to centre) between thick filaments in fibres at different states of contraction are so distributed in each "sarcomere' as to be compatible only with the wavy filaments.

Actin Cytoskeleton↗

PubMed1994

Cadmium-induced mRNA encoding a nonmetallothionein 33-kDa protein in Enchytraeus buchholzi (Oligochaeta).

Enchytraeus buchholzi (Oligochaeta) were exposed to various concentrations of CdCl2 in agar and aqueous solution. The Cd uptake was determined by atomic absorption spectroscopy as well as Cd effects on survival, reproduction, and mRNA synthesis by in vitro translation of total RNA in a rabbit reticulocyte lysate system. Although Cd was rapidly accumulated by the worms, any acute toxic Cd effects at concentrations below 4 mg Cd/liter were not detectable. However, such subtoxic Cd concentrations caused the induction of an mRNA species coding for a nonmetallothionein 33-kDa protein as revealed by 2D electrophoresis of in vitro translated in vitro translated proteins using [35S]methionine. The Cd-induced synthesis of this transcriptionally regulated protein might be a preindicator for a Cd intoxication in enchytraeids.

Animals↗

PubMed2006

Bioaccumulation and toxicity of 4-nonylphenol (4-NP) and 4-(2-dodecyl)-benzene sulfonate (LAS) in Lumbriculus variegatus (Oligochaeta) and Chironomus riparius (Insecta).

The discharge of surfactants, such as 4-nonylphenol (4-NP) and linear alkylbenzene sulfonates (LAS), into water bodies leads to accumulation of the chemicals in the sediments and may thus pose a problem to benthic organisms. To study the bioaccumulation of surfactants, Oligochaeta worm Lumbriculus variegatus was exposed to sediment-spiked, [14C]-labeled 4-NP and 4-(2-dodecyl)-benzene sulfonate (C12-LAS) in three different sediments (S1-S3). The sediments were characterized for organic carbon (OC) content and particle size distribution. The acute toxicity was examined by exposing L. variegatus and three to four instar Chironomus riparius (Insecta) larvae in water-only exposure to 4-NP and LAS at different concentrations. After 48-h exposure, lethal water concentrations (LC50) and lethal body residues (LBR50) were estimated using liquid scintillation counting. Chronic toxicity was evaluated in two different sediments by exposing first instar C. riparius larvae to sediment-spiked chemicals at different concentrations. After 10 days, the sublethal effects of surfactants were observed by measuring wet weight and head capsule length. Finally, another 10-day test was set up in order to measure the LAS body residues associated with sublethal effects in C. riparius in S2 sediment. The bioaccumulation test revealed that the bioaccumulation of both 4-NP and LAS increased as the sediment organic matter content decreased. It is assumed that the chemical binding to organic material decreased chemical bioavailability. The acute toxicity tests showed that L. variegatus was more tolerant of 4-NP, and C. riparius was more tolerant of LAS when based on water exposure concentration. The LBR-estimates revealed, however, that L. variegatus tolerated clearly higher tissue residues of both chemicals compared with C. riparius. Both chemicals had sublethal effects on C. riparius growth in sediment exposure, reducing larvae wet weight and head capsule size. 4-NP, however, showed an irregular dose-response pattern. The characteristics of the exposure media affected the bioaccumulation potential of both chemicals. Thus, exposure concentrations offered no prediction of body residue, and therefore it is proposed that organism body residue offered a more accurate dose-metric for chemical exposure than the chemical concentration of the environment.

Alkanesulfonic Acids↗

PubMed2006

Seasonal population dynamics of Eisenia fetida (Savigny, 1826) (Oligochaeta, Lumbricidae) in the field.

In order to assess the response of epigeic earthworms to seasonal changes we monitored the population dynamics of Eisenia fetida (Oligochaeta, Lumbricidae) in a manure heap in the field during a year. Earthworms were hand-sorted from five 0.25 x 0.25 x 0.20 m blocks around the heap in November (autumn) 1999 and in January (winter), April (spring) and August (summer) 2000 to determine earthworm population dynamics. Earthworms of each block were classified into different age classes: mature, preclitellate, juvenile, hatchling and cocoon, and afterwards counted and weighed. Seasonality had a strong effect on the density, biomass and reproductive activity of the population. The population of E. fetida was characterized by a high density of individuals and the predominance of mature individuals throughout the year. Maximum density, mating activity and size of cocoons were achieved in spring, but there were not changes in the number of cocoons per mature earthworm throughout the year. Unexpectedly, the smallest cocoons were produced in winter by the largest individuals. These results suggest that E. fetida is able to allocate resources to growth and/or reproduction in response to environmental fluctuations.

Aging↗

PubMed2006

The effect of cohabitation of Tubifex tubifex (Oligochaeta: Tubificidae) populations on infections to Myxobolus cerebralis (Myxozoa: Myxobolidae).

The competitive interactions between susceptible and resistant Tubifex tubifex (Oligochaeta: Tubificidae) exposed to Myxobolus cerebralis (Myxozoa: Myxobolidae) infections were investigated in two laboratory trials. Competition was assessed by the total parasite production over the course of the trials in mixed and pure cultures of M. cerebralis exposed worms, and by the genetic analyses of worms from the control and experimental groups at the beginning and end of the experiments. Mixed cultures of resistant and susceptible worms showed a 70% reduction in production of parasites released when compared with pure cultures of susceptible worms. In studies with laboratory and field-collected oligochaetes the mixed cultures at the end of the cohabitation experiments were dominated by resistant Tubifex from lineage V (HB strain) this strain of Tubifex has a competitive advantage over worms from other lineages. The results of this study suggest that certain species of Tubifex may be dead-end hosts to M. cerebralis by absorbing or inactivating the parasite and may also show greater survival compared to susceptible oligochaetes in certain whirling disease enzootic habitats.

Animals↗

PubMed2001

The asexual enchytraeid worm Cognettia sphagnetorum (Oligochaeta) has increased Cu resistance in polluted soil.

We studied Cu resistance in the asexual (reproduction through fragmentation) enchytraeid worms (Cognettia sphagnetorum, Oligochaeta) originating from two sites: one uncontaminated, and another contaminated by heavy metals. Adult worms were smaller and population density was lower at the polluted site. However, adults from the contaminated site had better survival in Cu-contaminated soil, but lower survival as juveniles (fragments). As we do not know the genetic basis of Cu resistance of the worms, it may have been reached by acclimatization via induced Cu regulation. Because fragmentation is the only mode of reproduction, all phenotypic properties (including resistance) of a parental generation could be transferred to filial generations.

Adaptation, Physiological↗

PubMed2005

Ultrastructural and molecular characterization of Bacillidium vesiculoformis n. sp. (Microspora: Mrazekiidae) in the freshwater oligochaete Nais simplex (Oligochaeta: Naididae).

The development of a new species, Bacillidium vesiculoformis n. sp. (Microspora, Mrazekiidae), is described from the freshwater oligochaete Nais simplex (Oligochaeta, Naididae). Initial stages of parasite development consist of a monokaryotic merogony within a haemocyte of the intestinal blood sinus. The resulting hypertrophied haemocyte is attached to the chloragocytes of the sinus by fine cytoplasmic extensions with the sinus around the cell becoming greatly enlarged. The meronts within the haemocyte form diplokaryotic sporonts that undergo sporogenesis directly within the cytoplasm of the host cell. The infected cell becomes packed with spores and developmental stages, causing it dramatically to increase in size, eventually rupturing the oligochaete and cell. Sporogony appears to be disporoblastic. Released spores were observed to have an adhesive quality. Transmission studies conducted with mature spores failed to transmit the parasite horizontally although vertical transmission was observed. Phylogenetic analysis of the parasite demonstrated that B. vesiculoformis clustered with microsporidian parasites of bryozoa and two other microsporidians, Janacekia debaiseuxi and an unidentified Bacillidium sp.

Animals↗

PubMed2000

Physical mapping of rDNA genes, (TTAGGG)n telomeric sequence and other karyological features in two earthworms of the family Lumbricidae (Annelida: Oligochaeta).

A cytogenetical study was carried out on the chromosomes and nuclear DNA amounts of the terrestrial earthworms Octodrilus complanatus and Eisenia foetida (Annelida: Oligochaeta: Lumbricidae). Chromosomes were studied using Giemsa staining, banding methods and fluorescent in situ hybridization (FISH) with two repetitive DNA probes [rDNA and (TTAGGG)n]. rDNA FISH and silver staining consistently identified one chromosome pair per spread in both species. The telomeric sequence (TTAGGG)n hybridized with termini of all the chromosomes in both earthworms. Flow cytometry DNA assays showed that O. complanatus and E. foetida had different nuclear DNA contents (2C value=1.72 and=1.40 pg, respectively) but very similar base composition in their genomes.

Animals↗

PubMed2000

Immunohistochemical localization of calcium-binding proteins (CaBPs) in the epidermis of the earthworm Lumbricus terrestris (Annelida, Oligochaeta).

The present immunohistochemical study provides the first evidence of the presence of calcium-binding proteins (CaBPs) in the epidermis of the earthworm Lumbricus terrestris (Annelida, Oligochaeta) a lower invertebrate. The entire epidermis was labelled for calmodulin which is in agreement with its ubiquitous occurrence. Immunopositivity for calbindin D28K was limited to mucous cells, while that for S-100 protein was present only in neuroendocrine-like small granular cells. Finally, labelling for parvalbumin was specifically present in the subcutaneous nerve plexus. S-100 protein is considered to be a marker of neuroendocrine cells, at least in lower invertebrates such as Annelida. Although calbindin D28K is considered to be a marker of these cells in vertebrates, the same function cannot be attributed in Lumbricus terrestris. However, we can conclude that S-100 protein, as a regulatory protein, is phylogenetically older than calbindin D28K. We assume that the latter has an autoregulatory function in secretory processes. In agreement with previous data, we suggest that small granular cells exert a paracrine action in osmoregulatory and secretory processes.

Animals↗

PubMedDate not supplied

rDNA (18S-28S and 5S) colocalization and linkage between ribosomal genes and (TTAGGG)(n) telomeric sequence in the earthworm, Octodrilus complanatus (Annelida: Oligochaeta: Lumbricidae), revealed by single- and double-color FISH.

Spermatogonial and metaphase I chromosomes of the lumbricid earthworm Octodrilus complanatus (Annelida: Oligochaeta) were examined using fluorescent in situ hybridization (FISH) with three repetitive DNA probes-5S rDNA, 18S-26S rDNA, and (TTAGGG)(n). Single-color FISH consistently mapped one chromosome pair per spread using either 5S rDNA or 18S-26S rDNA as probes. Simultaneous (18S-26S)-5S and (18S-26S)-(TTAGGG)(n) FISH demonstrated that repeated units of the two ribosomal families were overlapped and closely associated with telomeric sequences.

Animals↗

PubMed2001

On the origin of the Hirudinea and the demise of the Oligochaeta.

The phylogenetic relationships of the Clitellata were investigated with a data set of published and new complete 18S rRNA gene sequences of 51 species representing 41 families. Sequences were aligned on the basis of a secondary structure model and analysed with maximum parsimony and maximum likelihood. In contrast to the latter method, parsimony did not recover the monophyly of Clitellata. However, a close scrutiny of the data suggested a spurious attraction between some polychaetes and clitellates. As a rule, molecular trees are closely aligned with morphology-based phylogenies. Acanthobdellida and Euhirudinea were reconciled in their traditional Hirudinea clade and were included in the Oligochaeta with the Branchiobdellida via the Lumbriculidae as a possible link between the two assemblages. While the 18S gene yielded a meaningful historical signal for determining relationships within clitellates, the exact position of Hirudinea and Branchiobdellida within oligochaetes remained unresolved. The lack of phylogenetic signal is interpreted as evidence for a rapid radiation of these taxa. The placement of Clitellata within the Polychaeta remained unresolved. The biological reality of polytomies within annelids is suggested and supports the hypothesis of an extremely ancient radiation of polychaetes and emergence of clitellates.

Animals↗

PubMed2001

Life history and spatial distribution of the enchytraeid worm Cognettia sphagnetorum (Oligochaeta) in metal-polluted soil: below-ground sink-source population dynamics?

We studied the life history, metal-avoidance behavior, spatial distribution, and population growth of enchytraeid worms (Cognettia sphagnetorum [Oligochaeta]) originating from two sites: one uncontaminated, and another patchily polluted by heavy metals. Effects of patchy soil contamination on populations were studied in microcosms. In uncontaminated soil, worms from the polluted site had lower viability and reduced growth rate as juveniles but higher growth rate as adults compared to worms from the unpolluted site. They were also smaller in size at fragmentation (reproduction). Worms from the polluted site reached a larger population size than worms from the unpolluted site. Hence, worms from the polluted site seemed to allocate more energy to reproduction, because such a strategy can be highly adaptive when living in a less-polluted patch (the source) in, on average, a highly polluted environment. The C. sphagnetorum actively avoided Cu-contaminated soil, with the response being stronger in individuals from the contaminated site. When an unpolluted patch (the source) was surrounded by a toxic environment (the sink), worms were found in the sink, either because intraspecific competition overrode the avoidance behavior or because of random walk migration. As a result, total population size in these microcosms were as high as those in totally uncontaminated microcosms. Our results indicate that avoidance behavior and increased allocation to reproduction, together with the observed dispersal pattern, can be an adaptive strategy for C. sphagnetorum in the presence of small, less-polluted patches in, on average, a hostile environment. Hence, sink-source population regulation can explain spatial distribution and survival of C. sphagnetorum in patchily polluted field soils. When such population dynamics occur, this pattern should be taken into account when population densities in the field are monitored for ecological risk-assessment procedures concerning toxicants.

Adaptation, Physiological↗

PubMed1976

Accumulation and localization of lead in Eisenia foetida (Oligochaeta) tissues.

1. Accumulation and distribution of lead in tissues of Eisenia foetida (Oligochaeta) living in soils with different concentrations PbO2 was studied histochemically and with the use of the dithizione method. 2. The earthworms absorb lead from the soil through the alimentary canal as well as through the body wall. this leads to considerable accumulation of this metal in epithelial cells, especially in the epithelial gland cells of the body wall and of the alimentary tract. 3. High concentration of lead in the soil does not favour increased accumulation of lead in the earthworms' organisms. The histochemical data show that the most intense accumulation occurs when the concentration of PbO2 is 0-4 mg/1-00 g soil.

Air Pollutants↗

PubMedDate not supplied

[Cytogenetic and population effects in oligochaeta from the Chernobyl zone].

Research on intensity and character of reproduction of Oligochaeta (Dero obtusa, Nais pseudobtusa and Nais pardalis) was carried out in 1995-1996 in two water-bodies: a) in the Chernobyl NPP zone near Yanov Village, with a dose rate of 14 microGy h-1 on the surface of the bottom sediment; b) at the Uzh River area (the control water-body). The changes in both intensity and reproduction type were observed in worms at the radioactively polluted water-body. Stimulation of paratomic division in D. obtusa as well as activation of sexual reproduction in two other species were found out along with increasing of amount of cytogenetic damages in somatic cells.

Animals↗