Epithelia form protective barriers and regulate molecule transport between the mesenchyme and environment. Amongst all metazoans, only sponges are said to lack 'true' epithelia however the physiology of sponge cell layers are rarely studied empirically. Aggregates and gemmules of a freshwater demosponge, Spongilla lacustris, were used to grow confluent tissue over permeable culture wells which are required for transepithelial recordings. The transepithelial potential (TEP) of S. lacustris was slightly negative (-3mV), indicating possible control of ion transport. Transepithelial resistance (TER) was recorded between 1-2 k cm2, the same order of magnitude as many vertebrate epithelia. Cultures with high resistance blocked the passage of the small tracer molecules 14C-PEG, 3H-Inulin and ruthenium red. Pinacocytes were spatially stable over time and epithelial layers were morphologically similar in freshwater and marine species. These results suggest that sponge cell layers are able to control solute and ion transport, the physiological attributes of functional epithelia. / Physiology, Cell and Development Biology

Orientador: Marlene Tiduko Ueta / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T11:53:43Z (GMT). No. of bitstreams: 1 Correa_LincolnLima_M.pdf: 1163732 bytes, checksum: 5fe7ecad7d270d89129854e53cdaf3b0 (MD5) Previous issue date: 2009 / Resumo: Este estudo teve como objetivo a associação entre os índices hematológicos de Hoplias malabaricus (traíra), o parasitismo por monogeneas e outras espécies de metazoários e os fatores ambientais. O estudo ocorreu nas lagoas do CEPTA/ICMBio, localizada no município de Pirassununga, SP (21º55'55"S e 47º22'37"W), no período de fevereiro de 2008 a março de 2009 em 187 traíras. Verificou-se que os parâmetros sanguíneos não sofreram alterações significativas em relação ao estágio de maturação, sexo, período de coleta e intensidade de infecção de monogeneas. Porém, os peixes apresentaram valores significativamente positivos para biometria peso/comprimento (r=0,89 e p<0,0001) e os parâmetros ambientais pH/temperatura (r=0,71 e p<0,0001). Verificou-se que os monogeneas não atuaram como indicador ambiental nas lagoas, porém os parâmetros hematológicos revelaram uma maior sensibilidade ao ambiente. Em relação à análise dos outros metazoários, verificou-se uma diferença significativa em relação ao estágio de maturação e intensidade de infecção na Lagoa I (p=0,002) e na Lagoa II não houve diferença. Houve correlação significativa entre peso do peixe e intensidade de infecção na Lagoa I (r=0,50; p<0,001) e entre comprimento e a intensidade de infecção dos metazoários (r=0,42; p<0,001). Contudo, a intensidade média de parasita diferiu significativamente entre as lagoas estudadas. Os metazoários presentes em H. malabaricus também não atuaram como indicador ambiental. / Abstract: This study aimed at the association between blood indexes of Hoplias malabaricus (betrayed), the parasitism by monogeneans and other metazoan species and environmental factors. The study took place in ponds CEPTA / ICMBio, located in the city of Pirassununga, SP (21 º 55'55 "S and 47 º 22'37" W), from February 2008 to March 2009 in 187 traíras. It was found that the blood parameters did not change significantly in relation to the stage of maturation, sex, time of collection and intensity of infection of monogeneans. But the fish had significantly positive for biometrics weight / length (r = 0.89 and p <0.0001) and the environmental parameter pH and temperature (r = 0.71 and p <0.0001). It was found that the monogeneans not acted as an environmental indicator in the lakes , but the haematological parameters showed a greater sensitivity to the environment. On the analysis of the Metazoa, there was a significant difference in the stage of ripeness and intensity of infection in the Lake I (p = 0.002) and in Lake II there was no difference. There was significant correlation between weight of fish and intensity of infection in the Lake I (r = 0.50, p <0.001) and between length and intensity of infection of metazoan (r = 0.42, p <0.001). However, the mean intensity of parasites differed significantly between the lakes studied. The metazoan present in H. malabaricus also did not act as an environmental indicator. / Mestrado / Mestre em Parasitologia

Les Cnidaires et les Cténaires sont deux embranchements extérieurs aux Bilatériens qui, de par leur position phylogénétique, constituent des modèles d'étude cruciaux pour comprendre l'origine et l'évolution de mécanismes moléculaires ou encore de types cellulaires à grande échelle chez les Métazoaires. Ils sont les deux seuls embranchements non-Bilatériens à posséder des cellules nerveuses ainsi que des cellules musculaires. La première partie de mon travail de thèse s'inscrit dans le contexte de la compréhension de l'origine du système nerveux des Métazoaires. Des études récentes suggèrent une origine double du système nerveux ; ainsi celui des Cténaires aurait été acquis de manière convergente par rapport à celui des Cnidaires et des Bilatériens. Cela repose sur des données récentes de phylogénomique proposant les Cténaires en tant que groupe-frère de tous les autres Métazoaires et sur l'absence supposée chez les Cténaires de quasiment tous les systèmes de neurotransmission connus y compris le système cholinergique. A l'encontre de ces hypothèses, j'ai pu mettre en évidence l'existence d'un système cholinergique chez le Cténaire Pleurobrachia pileus ainsi que son étroite association avec le système nerveux. Cette conclusion repose sur une multiplicité d'approches à l'échelle moléculaire (analyses d'orthologie, immunolocalisation, hybridations in situ), cellulaire (imagerie calcique) et de l'organisme (approche pharmacologique). Dans la seconde partie de ma thèse, j'aborde la question de la conservation des mécanismes moléculaires impliqués dans le contrôle de la prolifération cellulaire à l'échelle des Métazoaires. J'ai pu mettre en évidence la conservation des acteurs. / Due to their phylogenetic position outside from Bilateria, cnidarians and ctenophores are key phyla to understanding the origin and early evolution of molecular mechanisms, cell types, or body plan features at the level of Metazoa. Unlike other non-bilaterian phyla (sponges and placozoans), they possess neurons and muscle cells. The first part of my work relates to the problem of the origin of the metazoan nervous system. Recent studies have suggested a dual origin for nerve cells, with ctenophore neurons having emerged independently from those of cnidarians and bilaterians. This hypothesis relies on phylogenomic analyses supporting ctenophores as sister-group to all other metazoans, and on the purported absence in ctenophores of almost all well-known neuro-transmission systems, including the cholinergic system. Refuting this claim, I present substantial evidence in favour of acetylcholine (Ach) being used in the ctenophore Pleurobrachia pileus as an extra-cellular messenger, including within the nervous system. This conclusion arises from the conjunction of multiple approaches at the molecular scale (orthology analyses, Ach immuno-localisation, gene in situ hybridisation), at the cellular scale (calcium imaging on muscle cells exposed to Ach) and at the organism scale (pharmacological treatments with an Ach analogue and Ach antagonists). In the second part of my thesis, I address the conservation of molecular mechanisms involved in the control of cellular proliferation. Notably, the Hippo pathway is known for its role in bilaterians in the negative control of cellular proliferation. I show that components of this pathway are conserved in Pleurobrachia pileus and in Clytia hemisphaerica and that the nuclear vs. cytoplasmic localisation of the transcriptional co-factor Yorkie is correlated to the extent of proliferation within C. hemisphaerica tissues. Finally, RNAseq differential gene expression analyses along a cellular conveyor belt of the C. hemisphaerica medusa suggests a tendency for conservation of function among a set of genes whose mammalian orthologues have documented roles in the arrest of cellular proliferation.

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The evolutionary origin and the phylogeny of higher metazoan taxa is still under debate although considerable progress has been made in the past 20 years. Metazoa represents a monophyletic group of highly diverse animals including Bilateria, Cnidaria, Porifera, Ctenophores, and Placozoa. Bilateria comprises the majority of metazoans and consists of three major clades: Deuterostomia, Spiralia (= Lophotrochozoa sensu lato), and Ecdysozoa, whereas the sister group taxa Spiralia and Ecdyzozoa form the monophyletic clade Protostomia. Molecular data have profoundly changed the view of the bilaterian tree of life. One of the main questions concerning bilaterian phylogeny is the on-going debate about the evolution of complexity in Bilateria. It was assumed that the last common ancestor of Deuterostomia, Ecdysozoa and Spiralia had a segmented and coelomate body organization resembling that of an annelid. On the contrary, the traditional view is the evolution of Bilateria from a simple body organization towards more complex forms, assuming that the last common ancestor of Bilateria resembles a platyhelminth-like animal without coelomic cavities and segmentation. To resolve this question, it is necessary to unravel the phylogenetic relationships within Bilateria. By using mitogenomic and phylogenomic data, this thesis had a major contribution to clarify phylogenetic relationships within problematic metazoan taxa: (1) the phylogeny of Deuterostomia, (2) the questionable monophyly of Platyzoa, and first assumptions concerning the phylogeny of Gnathostomulida, Gastrotricha and Polycladida, (3) phylogenetic relationships within annelid taxa, especially Terebelliformia, Diurodrilidae, and Syllidae, with new insights into the evolution of mitochondrial gene order, and (4) new insights into the evolution of annelids, especially the interstitial ones, as well as the colonization of the interstitial realm.