No presente estudo, duas espécies nativas, Hydra viridissima Pallas, 1766 e Hydra salmacidis Silveira, Gomes e Silva, 1997 foram estudadas visando obter informações sobre a biologia, a ecologia e a potencialidade destas espécies como organismos-teste em estudos ecotoxicológicos. Para isso, foram avaliados alguns aspectos de seus ciclos de vida, como as taxas de crescimento individual e populacional por meio do cultivo das hidras em laboratório, e foram investigados seus potenciais predadores e presas preferenciais dentre os principais componentes da comunidade de invertebrados aquáticos, presentes em corpos de água doce similares aos ambientes onde as espécies ocorrem naturalmente. Avaliou-se também o efeito de diferentes agentes tóxicos, tais como metais, sais, fármacos e surfactantes, às espécies estudadas, bem como seus efeitos sobre a capacidade de regeneração destas hidras. Além disso, avaliou-se a toxicidade de cianotoxinas e de amostras ambientais de água e sedimento aos organismos. Os resultados indicaram que macroinvertebrados, como as ninfas de Odonata, as larvas do Diptera Chaoborus sp. e os Copepoda Cyclopoida, além do peixe Poecilia reticulata, usuais predadores de invertebrados em águas doces, não consumiram as hidras, e que H. viridissima tem como presas preferenciais as fases jovens dos copépodos calanóides e pequenos cladóceros, enquanto que H. salmacidis, além destas presas, também tem preferência pelos organismos adultos dos copépodos calanóides. Os tempos de geração obtidos para as espécies de Hydra não diferiram significativamente entre si (5,2 ± 1,14 e 5,2 ± 0,79 dias para H. viridissima e H. salmacidis, respectivamente) e foram relativamente curtos, enquanto que H. viridissima apresentou um tempo de duplicação da população (6,38 ± 2,40 dias) significativamente maior do que H. salmacidis (4,11 ± 0,21 dias). Em relação à sensibilidade das hidras aos agentes tóxicos, as duas espécies foram bastante sensíveis quando comparadas a espécies de outros grupos de invertebrados rotineiramente utilizados como organismos-teste, e ora uma, ora outra espécie teve maior sensibilidade aos agentes tóxicos testados. Estas espécies nativas de Hydra são bastante adequadas para os estudos ecotoxicológicos por serem facilmente cultivadas, com baixo custo, e por responderem por meio de modificações morfológicas graduais às condições de crescente toxicidade, evidenciando, além das concentrações letais, as concentrações subletais de agentes tóxicos ou amostras ambientais. São, portanto, excelentes organismos-teste e devido à sua capacidade de regeneração podem ser utilizadas como indicadores de toxicidade. / In the present study, two native species, Hydra viridissima Pallas, 1766 and Hydra salmacidis Silveira, Gomes and Silva, 1997 were studied regarding their biology, ecology and performance as test organisms for ecotoxicological studies. Aspects of their life cycle such as individual and population growth rates were assessed by culturing them in the laboratory, and their potential predators and preferential preys were investigated among the main components of communities from water bodies similar to those in which the hydras naturally occur. Several acute ecotoxicological tests were performed to assess the effect of different compounds such as metals, salts, pharmaceuticals and surfactants to Hydra species. The effect of these toxicants on Hydra regeneration ability was also assessed. Besides that, tests were performed with cianotoxins and environmental samples of water and sediments. The results indicated that macroinvertebrates such as Odonata nymphs, Chaoborus sp. larvae (Diptera), Cyclopoida copepods, and the guppy Poecilia reticulata, usually predators of invertebrates in freshwaters, did not consume the hydras. It was also found that H. viridissima has positive food selection for the nauplii and copepodites of calanoid copepods and small cladocerans, whereas H. salmacidis, besides these preys, also have preference for adult calanoid copepods. Generation times did not significantly differ between the species of Hydra (5.2 ± 1.14 and 5.2 ± 0.79 days for H. viridissima and H. salmacidis, respectively) and were relatively short. H. viridissima had a population doubling time (6.38 ± 2.40 days) significantly longer than that of H. salmacidis (4.11 ± 0.21 days). Both species of Hydra had high sensitivity to the toxicant compounds tested when compared to other species of invertebrate groups routinely used as test organisms. Regarding the sensitivity to the compounds tested, one or the other species can be more sensitive depending on the compound. These native species of Hydra are suitable for as test organisms because: they can be easily and low costing laboratory cultured, and they respond to increasing toxicity by gradually changing their morphology showing lethal or sublethal effects of toxicants or contaminated environmental samples. They are therefore excellent test organisms and due to their ability to regenerate they can be used as toxicity indicators.

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 191-207).

University, Diss., 2002--Kiel.

No presente estudo, duas espécies nativas, Hydra viridissima Pallas, 1766 e Hydra salmacidis Silveira, Gomes e Silva, 1997 foram estudadas visando obter informações sobre a biologia, a ecologia e a potencialidade destas espécies como organismos-teste em estudos ecotoxicológicos. Para isso, foram avaliados alguns aspectos de seus ciclos de vida, como as taxas de crescimento individual e populacional por meio do cultivo das hidras em laboratório, e foram investigados seus potenciais predadores e presas preferenciais dentre os principais componentes da comunidade de invertebrados aquáticos, presentes em corpos de água doce similares aos ambientes onde as espécies ocorrem naturalmente. Avaliou-se também o efeito de diferentes agentes tóxicos, tais como metais, sais, fármacos e surfactantes, às espécies estudadas, bem como seus efeitos sobre a capacidade de regeneração destas hidras. Além disso, avaliou-se a toxicidade de cianotoxinas e de amostras ambientais de água e sedimento aos organismos. Os resultados indicaram que macroinvertebrados, como as ninfas de Odonata, as larvas do Diptera Chaoborus sp. e os Copepoda Cyclopoida, além do peixe Poecilia reticulata, usuais predadores de invertebrados em águas doces, não consumiram as hidras, e que H. viridissima tem como presas preferenciais as fases jovens dos copépodos calanóides e pequenos cladóceros, enquanto que H. salmacidis, além destas presas, também tem preferência pelos organismos adultos dos copépodos calanóides. Os tempos de geração obtidos para as espécies de Hydra não diferiram significativamente entre si (5,2 ± 1,14 e 5,2 ± 0,79 dias para H. viridissima e H. salmacidis, respectivamente) e foram relativamente curtos, enquanto que H. viridissima apresentou um tempo de duplicação da população (6,38 ± 2,40 dias) significativamente maior do que H. salmacidis (4,11 ± 0,21 dias). Em relação à sensibilidade das hidras aos agentes tóxicos, as duas espécies foram bastante sensíveis quando comparadas a espécies de outros grupos de invertebrados rotineiramente utilizados como organismos-teste, e ora uma, ora outra espécie teve maior sensibilidade aos agentes tóxicos testados. Estas espécies nativas de Hydra são bastante adequadas para os estudos ecotoxicológicos por serem facilmente cultivadas, com baixo custo, e por responderem por meio de modificações morfológicas graduais às condições de crescente toxicidade, evidenciando, além das concentrações letais, as concentrações subletais de agentes tóxicos ou amostras ambientais. São, portanto, excelentes organismos-teste e devido à sua capacidade de regeneração podem ser utilizadas como indicadores de toxicidade. / In the present study, two native species, Hydra viridissima Pallas, 1766 and Hydra salmacidis Silveira, Gomes and Silva, 1997 were studied regarding their biology, ecology and performance as test organisms for ecotoxicological studies. Aspects of their life cycle such as individual and population growth rates were assessed by culturing them in the laboratory, and their potential predators and preferential preys were investigated among the main components of communities from water bodies similar to those in which the hydras naturally occur. Several acute ecotoxicological tests were performed to assess the effect of different compounds such as metals, salts, pharmaceuticals and surfactants to Hydra species. The effect of these toxicants on Hydra regeneration ability was also assessed. Besides that, tests were performed with cianotoxins and environmental samples of water and sediments. The results indicated that macroinvertebrates such as Odonata nymphs, Chaoborus sp. larvae (Diptera), Cyclopoida copepods, and the guppy Poecilia reticulata, usually predators of invertebrates in freshwaters, did not consume the hydras. It was also found that H. viridissima has positive food selection for the nauplii and copepodites of calanoid copepods and small cladocerans, whereas H. salmacidis, besides these preys, also have preference for adult calanoid copepods. Generation times did not significantly differ between the species of Hydra (5.2 ± 1.14 and 5.2 ± 0.79 days for H. viridissima and H. salmacidis, respectively) and were relatively short. H. viridissima had a population doubling time (6.38 ± 2.40 days) significantly longer than that of H. salmacidis (4.11 ± 0.21 days). Both species of Hydra had high sensitivity to the toxicant compounds tested when compared to other species of invertebrate groups routinely used as test organisms. Regarding the sensitivity to the compounds tested, one or the other species can be more sensitive depending on the compound. These native species of Hydra are suitable for as test organisms because: they can be easily and low costing laboratory cultured, and they respond to increasing toxicity by gradually changing their morphology showing lethal or sublethal effects of toxicants or contaminated environmental samples. They are therefore excellent test organisms and due to their ability to regenerate they can be used as toxicity indicators.

The dispersal and dispersion patterns of Hydra fusca were examined. Hydra were placed in petri dishes at various densities. The water in the dishes was swirled forcing the animals to the center. The location of each animal was marked at time intervals thereafter. Analyses of the dispersal rates and dispersion patterns were made. Hydra dispersed from a central release point at a non-random rate. There was rapid movement from the center followed by a minimal daily movement. This eventually resulted in a uniform dispersion pattern at high densities in a limited environment. There was a relationship between the ratio of nearest neighbor distances to expected distances and the density. The inhibition of growth with an increase in density was demonstrated. The decrease of density through distribution of the polyps in a uniform pattern could be related to the release of a growth inhibiting substance into the medium.

Hydra vulgaris is a Cnidarian species with a life cycle containing only a polyp stage, and with a simple body plan in which ectodermal and endodermal epitheliomuscular cells play many roles. These two epithelia generate motion of the polyp by exerting contractile force on myonemes. The function of this musculature was studied on a system scale using whole-animal calcium imaging to measure functional activity in all epitheliomuscular cells simultaneously. This approach maps the diversity of functional activation patterns underlying the behavior of Hydra, and reveals that individual epitheliomuscular cells participate in multiple patterns using at least two different types of calcium signaling that propagate by different mechanisms and at vastly different rates. These studies establish the functional basis for the epithelial muscle systems of Cnidaria, revealing new operational principles and deep evolutionary ties to mechanisms of contractile activity that exist elsewhere in Metazoa.

In this research, important stress and redox regulatory genes present in Hydra vulgaris were isolated and characterized to facilitate our understanding of the evolution and mechanisms of stress response. H. vulgaris heat shock protein 70 (HvHSP70), extracellular copper zinc superoxide dismutase (HvECCuZnSOD), manganese superoxide dismutase (HvMnSOD), phospholipid peroxidase glutathione peroxidase (HvPHGPx) and monofunctional catalase (HvCatalase) were cloned and characterized with regard to stress response, phylogeny and molecular structure. The HSP70 gene isolated from H. vulgaris encodes a polypeptide of 650 amino acids (Mw=710,037) and is interrupted by three intron sequences. The 5' non-coding region of the HvHSP70 possessed the canonical heat shock elements. Phylogenetically HvHSP70 formed a distinct lineage. A molecular model generated for the N-terminal fragment of the HvHSP70 displayed the heat shock protein fold and domains of phosphotransferases. The EC-CuZnSOD cDNA isolated from H. vulgaris encodes a protein of 189 amino acids (Mw=20959.73); the first 19 amino acids constitute the presumed signal peptide. Phylogenetically HvEC-CuZnSOD is grouped with ECCuZnSODs from several organisms. A molecular model generated for the HvEC-CuZnSOD displayed the CuZnSOD (beta)-barrel fold. The MnSOD cDNA isolated from H. vulgaris encodes a protein of 219 amino acids (Mw=24348.75); the first 21 amino acids constitute the presumed mitochondria-targeting signal peptide. Phylogenetically HvMnSOD is clustered with mollusk and crustacean MnSODs. A molecular model generated for the HvMnSOD displayed the N-terminal long alpha antiparallel hairpin and the Cterminal mixed alpha/beta fold characteristic of MnSODs. The PHGPx gene isolated from H. vulgaris encodes a polypeptide of 168 amino acids (Mw=18746.51) including a TGA-encoded selenocysteine at residue 44 and lacks any intron. Phylogenetically HvPHGPx is grouped with PHGPxs from several organisms. A molecular model generated for the HvPHGPx displayed the thioredoxin fold. The 3'-end of a cDNA sequence encoding for 168 amino acids of the Cterminal end of a catalase was isolated from H. vulgaris. Phylogenetically HvCatalase is grouped with heme-containing monofunctional catalases. Hydrae exposed to thermal, starvation, oxidative and metal stress responded by regulating respective mRNA transcriptions suggesting that these genes are involved in stress and (anti)oxidative processes and may have potential as molecular biomarkers for assessing aquatic environment quality.

Techn. Universiẗat, Diss., 2007--Darmstadt.

Universiẗat, Diss., 2003--München.

Universiẗat, Diss., 2004--Kiel.