Dugesia Tigrina Research Articles

Nitric oxide synthase in the pharynx of the planarian Dugesia tigrina.

The distribution of the nicotinamide adenine dinucleotide phosphate-(NADPH) diaphorase reaction, an indicator of nitric oxide synthase activity, was studied in the freshwater planarian Dugesia tigrina (Platyhelminthes). The reaction was restricted to the pharynx, where the inner epithelium was intensely stained and the outer epithelium moderately stained. Neurons that innervated the pharynx were also stained. The enzyme activity was studied by high pressure liquid chromatographic quantitation of the formed citrulline. The presumed nitric oxide synthase was dependent on NADPH, whereas no dependency on Ca2+ and calmodulin could be detected. Tetrahydrobiopterin increased the activity about fivefold to 218.2+/-24.9 fmol/mg protein per min. Nomega-nitro-l-arginine depressed the enzyme activity by about 80%. The results indicate that nitric oxide has a role in the feeding behavior of planarians.

Development of the nervous system inDugesia tigrinaduring regeneration after fission and decapitation

Summary In the present study of Dugesia tigrina, the development of the nervous system is followed and compared during regeneration after fission and after decapitation. Immunocytochemistry was used, with antisera raised against the biogenic mine, 5-hydroxyhyptamine (5-HT) and the two neuropeptides, neuropeptide F (NPF), and FMRFamide. The results indicate that two processes are involved in the formation of the new cerebral ganglion. First, new processes sprouting from the original main longitudinal nerve cords bend transversely, indicating the position of the developing horseshoe-shaped anterior cerebral commissure. Then new nerve cells in front of the commissure differentiate from neoblasts and their growth cones fasciculate with the fibres from the old main longitudinal nerve cords. In the cerebral ganglion, 5-HT-IR cells appear before NPF-IR cells, in contrast to the pharynx where NPF-IR cells differentiate before the 5-HT-IR cells. In the peripheral nervous system, NPF-IR fibres and cells appear at a...

Myosin heavy chain gene in Dugesia (G.) tigrina: a tool for studying muscle regeneration in planarians.

Myosin heavy chain gene in Dugesia (G.) tigrina: a tool for studying muscle regeneration in planarians.

Regionalisation along the anteroposterior axis of the freshwater planarian Dugesia(Girardia)tigrina by TCEN49 protein.

Regionalisation along the anteroposterior axis of the freshwater planarian Dugesia(Girardia)tigrina by TCEN49 protein.

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian Dugesia tigrina.

We recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. We report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 microT. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 microV/m. The addition of either 51.1 or 78.4 microT DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas our previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling. These results together with those reported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fields.

The effects of group size on per capita ingestion in flatworms

SUMMARY1. We evaluated the effect of group size on the per capita ingestion rates of three species of flatworm, two of which actively group with conspecifics (Dugesia tigrina, D, dorotocephala) and employ mucus to capture prey, and a third species (Mesostoma ehrenbergii) that does not actively group but does use mucus to capture prey.2. As flatworm group size increased, daily per capita ingestion first increased and then decreased for D. tigrina and D. dorotocephala. In the case of D. tigrina this pattern was observed even at low predator densities. Ingestion rates of M. ehrenbergii were largely unaffected by group size.3. Results suggest that the observed changes in per capita ingestion rates with changes in group size previously reported for D. tigrina are related to their tendency for active grouping and are not directly a consequence of prey capture technique or experimental design.4. We argue that freshwater triclads in general, and D. tigrina in particular, represent an ideal model system for the development and testing of group foraging theory.

POU-domain sequences from the flatworm Dugesia tigrina

Redundant primers matching well-conserved sequences within vertebrate and invertebrate POU genes were used in the PCR (polymerase chain reaction) to detect three different POU-domain-containing genes within the genome of the flatworm, Dugesia tigrina. Two of these genes appear to be close homologues of class-III POU genes previously identified in Dugesia japonica, while the third represents a new class-III POU gene. Nucleotide sequences encoding highly related POU domains within the two species of planaria exhibited a surprisingly poor degree of shared identity. Since only class-III POU genes have been observed to date in flatworms, these genes may represent ancestral versions of the multiple classes of PO U genes that exist in vertebrates, and may play important roles in the development of metazoan nervous tissue.

Chromosomes of Temnocephala minor, an ectosymbiotic turbellarian on Australian crayfish found in Kagoshima Prefecture, with karyological notes on exotic turbellarians found in Japan

Records of exotic turbellarian species found in Japan are reviewed from taxonomic and karyological viewpoints. Temnocephala minor Haswell, 1888, an ectocommensal on a freshwater crayfish of Australia, was found from culture ponds of Cherax tenuimanus (introduced from W. Australia) in Kagoshima Prefecture. T. minor had the chromosome number of 2x = 18 (2sm + 2m + 2m + 2sm + 2m + 2m + 2m + 2sm + 2m). The following 3 species of exotic freshwater triclads were recorded from tanks and ponds used for tropical fish culture: Dugesia austroasiatica Kawakatsu, 1985 (2x = 16), Dugesia tigrina (Girard, 1850) (2x = 16) and Rhodax? sp. (3x = 24; 3x = 24 & 3x + 1LB + 1SB = 25 + 1SB). The following 3 species of exotic terrestrial triclads were recorded: Bipalium nobile Kawakatsu et Makino, 1982 (2x = 10), Bipalium kewense Moseley, 1878 (2x = 18), and Platydemus manokwari de Beauchamp, 1962 (n = 6, 2x = 12). An extensive occurrence of P. manokwari in the Southwest Islands of Japan may be due to an unexpected introduction of the animal in very recent years.

CDNA cloning and partial sequencing of homeobox genes in Dugesia japonica

In the freshwater planarian Dugesia japonica, four types of cDNAs of homeobox-containing genes have been isolated by screening a cDNA library using a homeobox guessmer. Partial sequencing analysis of two types of cDNAs revealed that one was a homolog of Dth2 which is a homeobox gene in Dugesia tigrina and another was similar to Distal-less gene in Drosophila. This suggests that planarians have many homeobox genes.

TCAV-1, a monoclonal antibody specific to epithelial pharyngeal cells in the planarian Dugesia (Girardia) tigrina. Application to pattern formation of the pharynx during regeneration

During regeneration in planarians, anterior (head and prepharyngeal) and posterior (postpharyngeal and tail) fragments rebuild one of the most peculiar structures of planarians: the pharynx and the pharynx cavity. Previous studies (see Bronsted, 1969, for a general review, and Asai, 1990, 1991, for anterior regeneration) have shown that within postpharyngeal pieces both structures appear in the old stump from clusters of undifferentiated cells. However, the lineage and differentiation of their elements (inner and outer epithelial cells, muscle layers, gland cells, nerve rings) and the overall pattern of growth and differentiation is not clear.

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

High copy number of highly similar mariner-like transposons in planarian (Platyhelminthe): evidence for a trans-phyla horizontal transfer.

Several DNA sequences similar to the mariner element were isolated and characterized in the platyhelminthe Dugesia (Girardia) tigrina. They were 1,288 bp long, flanked by two 32 bp-inverted repeats, and contained a single 339 amino acid open-reading frame (ORF) encoding the transposase. The number of copies of this element is approximately 8,000 per haploid genome, constituting a member of the middle-repetitive DNA of Dugesia tigrina. Sequence analysis of several elements showed a high percentage of conservation between the different copies. Most of them presented an intact ORF and the standard signals of actively expressed genes, which suggests that some of them are or have recently been functional transposons. The high degree of similarity shared with other mariner elements from some arthropods, together with the fact that this element is undetectable in other planarian species, strongly suggests a case of horizontal transfer between these two distant phyla.

Weak extremely-low-frequency magnetic fields and regeneration in the planarian Dugesia tigrina.

Extremely-low-frequency (ELF), low-intensity magnetic fields have been shown to influence cell signaling processes in a variety of systems, both in vivo and in vitro. Similar effects have been demonstrated for nervous system development and neurite outgrowth. We report that regeneration in planaria, which incorporates many of these processes, is also affected by ELF magnetic fields. The rate of cephalic regeneration, reflected by the mean regeneration time (MRT), for planaria populations regenerating under continuous exposure to combined DC (78.4 muT) and AC (60.0 Hz at 10.0 muTpeak) magnetic fields applied in parallel was found to be significantly delayed (P << 0.001) by 48 +/- 1 h relative to two different types of control populations (MRT approximately 140 +/- 12 h). One control population was exposed to only the AC component of this field combination, while the other experienced only the ambient geomagnetic field. All measurements were conducted in a low-gradient, low-noise magnetics laboratory under well-maintained temperature conditions. This delay in regeneration was shown to be dependent on the planaria having a fixed orientation with respect to the magnetic field vectors. Results also indicate that this orientation-dependent transduction process does not result from Faraday induction but is consistent with a Ca2+ cyclotron resonance mechanism. Data interpretation also permits the tentative conclusion that the effect results from an inhibition of events at an early stage in the regeneration process before the onset of proliferation and differentiation.

Acetylcholinesterase and Non-Specific Esterase Activities during the Regeneration of Planaria Dugesia tigrina (Girard)

Biochemical modification of the acetylcholinesterase (AChE) and non-specific esterases of a planarian species [Dugesia tigrina (Girard)] were studied as a function of regeneration. The enzymatic activities were measured in regenerating planarians at regular time intervals from the beginning of the regeneration process to the complete restoration of the animal. Both enzymatic activities were substantially altered during the regeneration process of caudal and cephalic segments. Polyacrylamide gel zymograms for soluble α-naphthyl acetate hydrolytic activity revealed four bands of activities. These activities were fractioned into two major on cation exchange high performance h between 6 and 7 and were inhibited by PMSF, TPCK, TLCK and n-ethyl maleimide.

Lipid concentration during the regeneration of the planarian Dugesia trigrina (Girard)

Biochemical modifications in lipid concentration were studied in the planarian Dugesia tigrina (Girard) as a function of the regeneration process. The concentration of total lipids, triglyceride, phospholipid, cholesterol, lipase activity and labelled 14C-cholesterol were measured in regenerating planarians at regular time intervals from the beginning of regeneration to the complete restoration of the whole animal. Lipid concentration was substantially modified during the regeneration period. Significant differences in terms of metabolic parameters were observed between cephalic and caudal segments.

Gamma-Aminobutyric acid in the nervous system of a planarian.

The amino acid gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in both vertebrates and invertebrates. Despite this, no reports of GABA in flatworms have to date been published. We have studied the presence of GABA in the planarian Dugesia tigrina with immunocytochemical methods and high-pressure liquid chromatography. Fibers showing GABA-like immunoreactivity (GABA-IR) were present in abundance in the longitudinal nerve cords and lateral nerves. GABA-IR was revealed in fibers forming commissures in the brain. The ventral part of the subepidermal plexus showed GABA-IR. No cell somata containing GABA-IR could be identified with certainty. The chromatographic analysis showed that the average GABA concentration in D. tigrina is 533.6 pmol/mg protein. This is substantially higher than the concentrations of dopamine (62.87 pmol/mg) and serotonin (233.20 pmol/mg). An enzyme assay confirmed the capacity for GABA-synthesis in D. tigrina. The results indicate that GABA-containing neurons appeared earlier in evolution than was previously thought and that GABA may serve an important role already in the flatworms.

Effects of organophosphorus insecticides on Dugesia tigrina: cholinesterase activity and head regeneration.

Effects of organophosphorus insecticides on Dugesia tigrina: cholinesterase activity and head regeneration.

Effects of water quality on survival and reproduction of four species of planaria (Turbellaria: Tricladida)

Summary In a series of bioassays, four planarian species—Dugesia dorotocephala (Woodworth), Dugesia tigrina (Girard), Cura foremanii (Girard), Dendrocelopsis vaginatus (Hyman)—were evaluated against six water quality parameters (hardness, temperature, salinity, pH, dissolved organics, and dissolved oxygen) for effects on species survival and asexual reproduction. No significant (P<0.05) effects were determined on survival and asexual reproduction of three species exposed to various levels of hardness. Dugesia tigrina was determined to have a significant increase in asexual reproduction with an increase in hardness. Dissolved oxygen was determined to be a critical parameter affecting both survival and reproduction of the species evaluated. Dugesia dorotocephala and D. tigrina were determined to be the most adaptable and tolerant of the species evaluated.

Short- And Long-Term Consequences of Grouping and Group Foraging in the Free-Living Flatworm Dugesia tigrina

We evaluated the short-term effect of group size on the per capita ingestion rates, and the long-term reproductive and fitness consequences of group living in the free-living triclad, Dugesia tigrina. As D. tigrina group size increased, daily per capita ingestion rates first increased and peaked at a group size of approximately four, then decreased until, at larger group sizes, ingestion rates did not differ from those experienced by solitary foragers. The general qualitative pattern of changing per capita ingestion rates with changes in group size was not affected by changes in prey density, prey species or predator size

Changes in energetic substrates during the regeneration of planarians Dugesia tigrina (Girard)

1. 1. Biochemical modification of the energy substrates of a planarian species [ Dugesia tigrina (Girard)] were studied as a function of regeneration. 2. 2. The activities of creatine kinase (CPK), assays of ATP, glycogen and the incorporation of [U- 14C]glucose in glycogen were measured in regenerating planarians at regular intervals of time from the beginning of the regenerative process to the complete restoration of the animal. 3. 3. The enzymatic activities and metabolites were substantially altered during the regeneration period of cephalic as well as caudal segments. 4. 4. The analysis of ultrastructural sites of glycogen by ultracytochemical assays showed differences during the regeneration of cephalic and caudal segments.