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No description available.

The environment of bivalve Sanguinolaria rostrata growth and reproduction is affected by temperature, salinity and algal concentration.The growth and fattening of the bivalves is closely associated with filter-feeding. Hence, the present work was to investigate the effect of temperature, salinity and algal concentration on the filter-feeding of the bivalves. The salinity ranging from 5 to 30 at the interval of 5 psu, four temperatures at 20¢X, 25¢X, 27¢X and 30¢J, and three algal concentrations of each Isochrysis galbana and each Chaetoceros gracilis, 104 , 105 and 106 cells/ml, were used. Algal concentration was measured each hour and each test run last for 6 hours. A peak appeared at the salinity of 20 psu in each clearance rate vs salinity curve and clearance rate decreased with increasing algal concentration; a peak also appeared at the salinity of either 15¡ã20 psu in the ingestion rate vs salinity curve; and ingestion rate and the amount of pseudofaeces increased with increasing algal concentration. Under the conditions of algal concentration 104 cells/ml and temperature range 20¢X~30¢J, a peak appeared at 25¢J in each clearance rate and each ingestion rate vs temperature curves, and the greatest peak of clearance rate was 1.13 l/h; and the amount of pseudofaeces was the greatest at 25¢J and 20 psu. The bivalves fed with Isochrysis galbana have greater clearance and ingestion rates but less amount of pseudofaeces, compared to those fed with Chaetoceros gracilis.

Planktonic microalgae’s bloom can cause losses in aquaculture outputs or even damages in areas of cultivation because of the depletion of oxygen dissolved in water, being favored by the addition of chemical substances that are rich in phosphorus and nitrogen configuring the aquatic cultural eutrophication. This paper aimed to verify the potentiality of the Dendrocephalus brasiliensis (branchoneta) in the phytoplankton’s top-down control and such a protein source in aquaculture. In the experiment, that consisted of six treatments (0, 20, 40, 60, 80 e 100 bc.L-1) with four repetitions, eutrophicated water from the CHESF fish station was used, in aquariums, analyzing the interferences of the branchoneta (bc) in the algae’s composition and in the water’s quality throughout one infradian cycle. To perceive the brachoneta’s biofiltration qualitative and quantitative analyses of phytoplankton found in its intestinal content and in water samples were made, and to identify its food preference, Manly´s was used. The trophic state (ET) of water was analyzed using the Nygaard, Carlson indices modified by Lamparelli, Hâkanson and Boulion. Enzymatic experiments were carried out with the branchoneta’s extract and for the proteolytic activities unspecified and specific substrates were used. The output of hydrolyzed protein from branchoneta (HPB) occurred by enzymatic autolysis in different concentrations, calculating the percentage of hydrolysate protein in the reaction. In the electrophoresis and zymogram gels with concentration and separation in 4% and 12,5% respectively were used. According to the results 92 species of phytoplankton were identified. The cyanobacteria Anabaena sp. and Geitlerinema amphibium are among the preferred species in the branchoneta’s feed. It was identified that with 6 h there was efficiency of filtration in the densities of 80 and 100 bc.L-1. Also the change from eutrophic’s ET to oligotrophic by the Nygaard’s index was observed. The analysis of chlorophyll type a testified changes in water’s ET to an inferior level, using Hâkanson and Lamparelli. Notwithstanding, alteration of ET for the indices that use phosphorus did not occur, despite the fact that they differ statistically. In the treatment with 100 bc.L-1 the small values of chlorophyll a (15,07 ± 3,35 μg.L-1) and the bigger values of ammonia (3.463,27 ± 277,42 μg.L-1), phosphorus amount (1.867,84 ± 207,19 μg.L-1) and nitrite (7,57 ± 2,43 μg.L-1) occurred. Even increasing the levels of nitrogen and phosphorus in the water there was a diminution in the levels of chlorophyll a, probably because of the branchoneta’s filter feeding over the population of phytoplankton. About the HPB, 79,67% of crude protein that constitutes a good source of essentials amino acids with values that are bigger than the values of flours of menhaden and soya, and with chemical score of amino acids that fulfill the necessity of youth carnivore shrimps. The conclusion is that the biomaniputation of D. brasiliensis on the top-down control of phytoplankton occurred in an efficient way, characterizing the bioremediation on eutrophicated ambient with changes of ET. The HPB shows a potential to be inserted in rations like a protein component, and even like a flavor booster because it shows attractive amino acids with umami flavor. / O florescimento de microalgas planctônicas pode ocasionar perda da produção aquícola ou inviabilizar áreas para o cultivo, por causa da depleção de oxigênio dissolvido na água, sendo favorecido pelo aporte de substâncias químicas ricas em fósforo e nitrogênio, configurando assim a eutrofização aquática cultural. O objetivo deste trabalho foi verificar a potencialidade de Dendrocephalus brasiliensis (branchoneta) no controle top-down do fitoplâncton e como fonte proteica na aquicultura. No experimento, que constou de seis tratamentos (0, 20, 40, 60, 80 e 100 bc.L-1) com quatro repetições, foi utilizada água eutrofizada da estação de piscicultura da CHESF, em aquários, sendo analisadas as interferências da branchoneta (bc) na composição algal e na qualidade da água durante um ciclo infradiano. Para constatar a biofiltração da brachoneta foram realizadas análises quali-quantitativas do fitoplâncton encontrado no seu conteúdo intestinal e nas amostras de água, e para identificação de sua preferência alimentar usou-se o Manly´s . O estado trófico (ET) da água foi analisado utilizando os índices de Nygaard, Carlson modificado por Lamparelli, Hâkanson e Boulion. Foram também realizados ensaios enzimáticos com o extrato da branchoneta, e para as atividades proteolíticas fez-se uso de substratos inespecíficos e específicos. A produção do hidrolisado proteico de branchoneta (HPB) aconteceu por autólise enzimática em diferentes concentrações, sendo calculado o percentual de proteína hidrolisada na reação. Na eletroforese e no zimograma foram usados géis de concentração e de separação a 4% e 12,5%, respectivamente. Segundo os resultados foram identificadas 92 espécies de fitoplâncton. As cianobactérias Anabaena sp. e Geitlerinema amphibium encontram-se entre as espécies preferidas na alimentação da branchoneta. Verificou-se que com 6 h houve eficiência de filtração nas densidades de 80 e 100 bc.L-1. Também foi constatada a mudança do ET de eutrófico para oligotrófico utilizando o índice de Nygaard. As análises de clorofila a comprovaram mudanças do ET da água para um nível inferior, utilizando Hâkanson e Lamparelli. Porém, não houve alteração do ET para os índices que utilizam o fósforo, apesar de deferirem estatisticamente. No tratamento com 100 bc.L-1 ocorreram os menores valores de clorofila a (15,07 ± 3,35 μg.L-1) e os maiores valores de amônia (3.463,27 ± 277,42 μg.L-1), fósforo total (1.867,84 ± 207,19 μg.L-1) e nitrito (7,57 ± 2,43 μg.L-1). Mesmo com o aumento dos níveis de nitrogênio e fósforo na água houve uma diminuição nos níveis de clorofila a, provavelmente pela filtro-alimentação da branchoneta sobre a população fitoplanctônica. Quanto ao HPB, este apresentou 79,67% de proteína bruta, sendo uma boa fonte de aminoácidos essenciais com valores superiores aos das farinhas de menhaden e de soja, e com escore químico de aminoácidos que atende as exigências de camarões carnívoros na fase juvenil. Conclui-se que a biomanipulação de D. brasiliensis no controle top-down do fitoplâncton aconteceu de forma eficiente, caracterizando uma biorremediação no ambiente eutrofizado com mudança de ET. O HPB apresenta potencial para ser inserido em rações como componente proteico, e ainda como intensificador de sabor por apresentar aminoácidos atrativos com sabor umami.

L’embranchement Hemichordata regroupe les classes Enteropneusta et Pterobranchia. Hemichordata constitue, avec l’embranchement Echinodermata, le groupe-frère des chordés. Les entéropneustes sont des organismes vermiformes solitaires qui vivent sous ou à la surface du substrat et s’alimentent généralement par déposivorie, alors que les ptérobranches sont des organismes coloniaux filtreurs habitant dans un réseau de tubes appelé coenecium. Ce mémoire présente trois études dont le point commun est l’utilisation des hémichordés actuels pour répondre à des questions concernant l’évolution des hémichordés, des chordés, et du super-embranchement qui les regroupe, Deuterostomia. Notre première étude démontre que les fentes pharyngiennes, l’organe pré-oral cilié (POCO) et le pharynx de l’entéropneuste Protoglossus graveolens sont utilisés pour l’alimentation par filtration. Le système de filtration de P. graveolens permet la capture de particules jusqu’à 1.3 um, à un débit de 4.05 mm.s-1, pour une demande énergétique de 0.009 uW. Les similarités structurales et fonctionnelles avec le système de filtration des céphalochordés suggèrent que la filtration pharyngienne est ancestrale aux deutérostomes. Lors de notre deuxième étude, nous avons exploré l’hypothèse selon laquelle le POCO des entéropneustes, une structure ciliée pré-buccale au rôle possiblement chémorécepteur, serait homologue au « wheel organ » des céphalochordés et à l’adénohypophyse des vertébrés. Pour cela, nous avons déterminé par immunohistochimie l’expression de Pit-1, un facteur de transcription spécifique à ces deux structures, chez l’entéropneuste Saccoglossus pusillus. Pit-1 est exprimé dans des cellules sensorielles du POCO, mais aussi dans des cellules épithéliales distribuées dans le proboscis, collet et tronc. Ce patron d’expression ne permet pas de confirmer ou rejeter l’homologie du POCO et de l’adénohypophyse des vertébrés. Lors de notre troisième étude, nous avons caractérisé l’ultrastructure du coenecium des ptérobranches Cephalodiscus hodgsoni, Cephalodiscus nigrescens et Cephalodiscus densus par microscopie électronique à transmisison et à balayage. Cephalodiscus est le groupe frère de Graptolithina, un groupe qui inclut les graptolithes éteints ainsi que les ptérobranches du genre Rhabdopleura. Nous avons décrit les types de fibrilles de collagène présents, leur taille et leur organisation, ainsi que l’organisation globale du coenecium. Nous avons ainsi démontré la présence chez Cephalodiscus d’une organisation similaire au paracortex, pseudocortex et eucortex des graptolithes. La présence chez Cephalodiscus de ce type d’organisation suggère que le cortex est ancestral à la classe Pterobranchia. Ces trois études illustrent plusieurs axes importants de la recherche sur les hémichordés, qui en intégrant des données morphologiques, fonctionnelles et moléculaires permet de reconstruire certains évènements clés de l’évolution des deutérostomes. / The phylum Hemichordata comprises the classes Enteropneusta and Pterobranchia. Together with echinoderms, hemichordates are the sister-group to chordates. Enteropneusts are worm-shaped solitary deposit feeders. Pterobranchs are colonial filter feeders that live in a secreted collagenous domicile called a coenecium. In this thesis, three studies are presented. These studies are based on observations of extant hemichordates, and adress a variety of issues relating to the evolution of hemichordates, chordates, and the super-phylum to which they belong: Deuterostomia. Our first study demonstrates that the gill slits, pre-oral ciliary organ (POCO), and lining of the pharynx of the enteropneust Protoglossus graveolens are used in filter feeding. The filter-feeding system of P. graveolens enables particle capture down to 1.3 um, at a rate up to 4.05 mm.s-1, with a power consumption of 0.009 uW. Structural and functional similarities with the cephalochordate filter-feeding system suggest that pharyngeal filter-feeding is ancestral to the deuterostomes. In our second study, we address the hypothesis that the enteropneust POCO, a putative chemosensory structure located anterior to the mouth, is homologous to the cephalochordate wheel organ and vertebrate adenohypophysis. We characterized the expression pattern of the adenohypophysis-specific transcription factor Pit-1 in the adult enteropneust Saccoglossus pusillus with immunohistochemistry. Pit-1 is expressed in sensory cells of the POCO and in scattered epithelial cells of the proboscis, collar and trunk. This expression pattern does not allow to confirm or reject the homology of the POCO with the vertebrate adenohypophysis. In our third study, we characterized the ultrastructure of the coenecium of the pterobranchs Cephalodiscus hodgsoni, Cephalodiscus nigrescens and Cephalodiscus densus using transmission and scanning electron microscopy. Cephalodiscus is the sister-group to the Graptolithina, which includes the extinct graptolites and the extant pterobranch genus Rhabdopleura. We described the fibril types, size and organization, as well as the general organization of the coenecium. We demonstrated that the coenecium of Cephalodiscus shows similarities with the graptolite eucortex, paracortex and pseudocortex. The cortical-like organization of the coenecium of Cephalodiscus suggests that the cortex is ancestral to the Pterobranchia. Together, these three studies illustrate different axes of hemichordate research, and show how integrating morphological, functional and molecular data allows us toinfer key events in the evolution of deuterostomes.

L’embranchement Hemichordata regroupe les classes Enteropneusta et Pterobranchia. Hemichordata constitue, avec l’embranchement Echinodermata, le groupe-frère des chordés. Les entéropneustes sont des organismes vermiformes solitaires qui vivent sous ou à la surface du substrat et s’alimentent généralement par déposivorie, alors que les ptérobranches sont des organismes coloniaux filtreurs habitant dans un réseau de tubes appelé coenecium. Ce mémoire présente trois études dont le point commun est l’utilisation des hémichordés actuels pour répondre à des questions concernant l’évolution des hémichordés, des chordés, et du super-embranchement qui les regroupe, Deuterostomia. Notre première étude démontre que les fentes pharyngiennes, l’organe pré-oral cilié (POCO) et le pharynx de l’entéropneuste Protoglossus graveolens sont utilisés pour l’alimentation par filtration. Le système de filtration de P. graveolens permet la capture de particules jusqu’à 1.3 um, à un débit de 4.05 mm.s-1, pour une demande énergétique de 0.009 uW. Les similarités structurales et fonctionnelles avec le système de filtration des céphalochordés suggèrent que la filtration pharyngienne est ancestrale aux deutérostomes. Lors de notre deuxième étude, nous avons exploré l’hypothèse selon laquelle le POCO des entéropneustes, une structure ciliée pré-buccale au rôle possiblement chémorécepteur, serait homologue au « wheel organ » des céphalochordés et à l’adénohypophyse des vertébrés. Pour cela, nous avons déterminé par immunohistochimie l’expression de Pit-1, un facteur de transcription spécifique à ces deux structures, chez l’entéropneuste Saccoglossus pusillus. Pit-1 est exprimé dans des cellules sensorielles du POCO, mais aussi dans des cellules épithéliales distribuées dans le proboscis, collet et tronc. Ce patron d’expression ne permet pas de confirmer ou rejeter l’homologie du POCO et de l’adénohypophyse des vertébrés. Lors de notre troisième étude, nous avons caractérisé l’ultrastructure du coenecium des ptérobranches Cephalodiscus hodgsoni, Cephalodiscus nigrescens et Cephalodiscus densus par microscopie électronique à transmisison et à balayage. Cephalodiscus est le groupe frère de Graptolithina, un groupe qui inclut les graptolithes éteints ainsi que les ptérobranches du genre Rhabdopleura. Nous avons décrit les types de fibrilles de collagène présents, leur taille et leur organisation, ainsi que l’organisation globale du coenecium. Nous avons ainsi démontré la présence chez Cephalodiscus d’une organisation similaire au paracortex, pseudocortex et eucortex des graptolithes. La présence chez Cephalodiscus de ce type d’organisation suggère que le cortex est ancestral à la classe Pterobranchia. Ces trois études illustrent plusieurs axes importants de la recherche sur les hémichordés, qui en intégrant des données morphologiques, fonctionnelles et moléculaires permet de reconstruire certains évènements clés de l’évolution des deutérostomes. / The phylum Hemichordata comprises the classes Enteropneusta and Pterobranchia. Together with echinoderms, hemichordates are the sister-group to chordates. Enteropneusts are worm-shaped solitary deposit feeders. Pterobranchs are colonial filter feeders that live in a secreted collagenous domicile called a coenecium. In this thesis, three studies are presented. These studies are based on observations of extant hemichordates, and adress a variety of issues relating to the evolution of hemichordates, chordates, and the super-phylum to which they belong: Deuterostomia. Our first study demonstrates that the gill slits, pre-oral ciliary organ (POCO), and lining of the pharynx of the enteropneust Protoglossus graveolens are used in filter feeding. The filter-feeding system of P. graveolens enables particle capture down to 1.3 um, at a rate up to 4.05 mm.s-1, with a power consumption of 0.009 uW. Structural and functional similarities with the cephalochordate filter-feeding system suggest that pharyngeal filter-feeding is ancestral to the deuterostomes. In our second study, we address the hypothesis that the enteropneust POCO, a putative chemosensory structure located anterior to the mouth, is homologous to the cephalochordate wheel organ and vertebrate adenohypophysis. We characterized the expression pattern of the adenohypophysis-specific transcription factor Pit-1 in the adult enteropneust Saccoglossus pusillus with immunohistochemistry. Pit-1 is expressed in sensory cells of the POCO and in scattered epithelial cells of the proboscis, collar and trunk. This expression pattern does not allow to confirm or reject the homology of the POCO with the vertebrate adenohypophysis. In our third study, we characterized the ultrastructure of the coenecium of the pterobranchs Cephalodiscus hodgsoni, Cephalodiscus nigrescens and Cephalodiscus densus using transmission and scanning electron microscopy. Cephalodiscus is the sister-group to the Graptolithina, which includes the extinct graptolites and the extant pterobranch genus Rhabdopleura. We described the fibril types, size and organization, as well as the general organization of the coenecium. We demonstrated that the coenecium of Cephalodiscus shows similarities with the graptolite eucortex, paracortex and pseudocortex. The cortical-like organization of the coenecium of Cephalodiscus suggests that the cortex is ancestral to the Pterobranchia. Together, these three studies illustrate different axes of hemichordate research, and show how integrating morphological, functional and molecular data allows us toinfer key events in the evolution of deuterostomes.