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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The significance of placental and placental-like alkaline phosphatases in tumor biology and their potential use in clinical practice

Jeppsson, Annika January 1984 (has links)
Placental alkaline phosphatase (PLAP) is a membrane bound enzyme normally synthesized by the syncytiotrophoblasts in the human placenta. Recent studies have indicated that trace amounts of placental-like alkaline phosphatases also are present in several normal organs like testes and endocervix. PLAP and PLAP-1ike enzymes are furthermore synthesized by some tumors and can be detected in sera of approximately 12 % of patients with any type of cancer, more often in patients with genital tumors. This synthesis has been considered to be ectopic.PLAP is known to be electrophoretically highly polymorphic. Both poly- and monoclonal antibodies were used to study this enzyme. One of the monoclonal antibodies was able to discriminate between different phenotypes of PLAP and thus immunochemical approaches to elucidate enzyme polymorphism were established.To evaluate the potential clinical use of PLAP as a tumor marker serum levels of the enzyme were measured by a radioimmunoassay in 100 patients with the testicular tumor seminoma. Elevated levels of PLAP were found in 43 % of the patients with primary tumors and in 75 % of the patients with recurrent or metastatic disease. After successful treatment of seminoma the PLAP levels decreased. This indicates that measuring PLAP give useful information during follow up of treatment of seminomas.The content of PLAP-like enzymes in seminoma tumors was determined in 13 typical seminomas. The levels, of enzyme found in the tumor tissue ranged from 870-13 404 ng/g wet weight, which should be compared to around 100 ng/g in normal testes. Analysis using monoclonal antibodies and enzyme inhibitors showed the PLAP-like enzymes present in seminomas to be similar to the enzymes in normal testes. This suggests that the increased expression of PLAP-like enzymes in seminomas results from an enhanced eutopic expression of enzymes found in normal testis.A sensitive catalytic assay was used to quantify enzyme levels in sera from women with malignant gynaecological tumors. In the group of patients with cervical carcinoma 68 % had values exceeding the normal limit. For patients with ovarian cancer and carcinoma of the breast the percentages were 35 and 23 respectively.Monoclonal and polyclonal antibodies against PLAP were evaluated for tumor immunolocalization of human PLAP-producing tumors in nude mice.The antibodies were labeled with "125j and injected into mice with tumors. The distribution of 25j_an-ti-PLAP in various tissues showed that the labeled antibodies were enriched in the tumors, with a mean concentration ratio of 7. This indicates that there is a potential use of PLAP in localizing tumors in humans. / <p>S. 1-37: sammanfattning, s. 39-88: 5 uppsatser</p> / digitalisering@umu
2

Evolution of stomata in mosses (Bryophyta): From molecules to form and function

Merced-Alejandro, Amelia 01 May 2015 (has links)
As one of the first land plant groups to diversify, mosses are central in understanding the origin, diversification, and early function of stomata. Unlike tracheophytes that have stomata on anatomically complex leaves and stems, mosses bear stomata exclusively on spore-bearing organs (capsules). However, stomata do not occur in all mosses and, indeed, are absence in the earliest-divergent mosses (Takakia, Andreaea, Andreaeobryum and Sphagnum), suggesting that stomata originated in mosses independently of other plants. The occurrence of structurally unique pseudostomata in Sphagnum further confounds the resolution of homology of moss stomata with those of other plants. The five studies included in this dissertation are aimed at clarifying the structure, development and evolution of moss stomata. The first study focuses on the sporophyte anatomy and stomatal ultrastructure in two structurally and phylogenetically divergent mosses, Oedipodium and Ephemerum. Oedipodium is the sister to peristomate mosses and the first extant moss with true stomata. This monospecific genus has an elaborated capsule with an extended apophysis bearing numerous long-pored stomata. In contrast, Ephemerum nests within the peristomate mosses and has a reduced capsule that lacks an apophysis and has a few round-pored stomata. Ultrastructure of stomata is similar in these two mosses and comparable to that of tracheophytes, except that the stomata of mosses are not as structurally distinct from epidermal cells as are tracheophyte stomata. Anatomical features such as the presence of a cuticle, water-conducting cells, and spongy tissues with large areas for gas exchange are more pronounced in Oedipodium sporophytes and support the role of stomata in gas exchange and water transport during development and maturation. The second study examines changes in pectin composition during development in the model moss Funaria. Stomatal movement in tracheophytes requires guard cell walls to be strong, yet flexible, because they have to undergo reversible deformation to open and close the pore. Pectins are necessary for wall flexibility and proper stomatal functioning in seed plants. In this study of Funaria, immunogold-labeling using five antibodies to pectin epitopes was conducted on guard cell walls during development to relate these features to the limited movement of stomata in moss. Movement of Funaria stomata coincides with capsule expansion when guard cell walls are thin and pectinaceous. Walls dramatically increase in thickness after pore formation and the pectin content significantly decreases in mature guard cell walls, suggesting that a decrease in flexibility is responsible for the inability to open a close previously reported in older moss guard cells. Because this was the first study to demonstrate changes in pectin composition during stomatal development in any plant, a similar study was done on Arabidopsis to identify the main types of pectins in guard cell walls. Localization of pectins in guard cell walls of Arabidopsis is similar to mosses in the stage they can move, with homogeneous walls rich in arabinan pectins that are required for wall flexibility. This study extends knowledge of pectin composition from stomata of the moss Funaria with limited stomatal movement to an angiosperm in which stomatal activity is crucial to the physiological health of the plant. The fourth study describes stomata development and internal changes in sporophyte anatomy that lead to formation of air spaces in the moss Funaria. Developing sporophytes at different stages were examined using light, fluorescence and electron microscopy; immunogold-labeling was used to investigate the presence of pectin in the newly formed cavities. Stomata in mosses do not develop from a self-generating meristemoid like in Arabidopsis, but instead they originate from a protodermal cell that differentiates directly into a guard mother cell. Epidermal cells develop from protodermal or other epidermal cells, i.e., there are no stomatal lineage ground cells. This developmental pattern is congruent with the presence of a gene ortholog of FAMA, but not SPCH and MUTE, in Physcomitrella. The final study in this dissertation focuses on the enigmatic Sphagnum. Although true stomata are absent in early-divergent mosses, Sphagnum has specialized epidermal cells, pseudostomata, that partially separate but do not open to the inside. To further understand the structure, function and evolution of pseudostomata, capsule anatomy and ultrastructure of pseudostomata were detailed. As in moss stomata, pseudostomata wall architecture and behavior facilitate capsule dehydration, shape change, and dehiscence, supporting this common function. Unlike other moss stomata, pseudostomata collapse along their ventral walls and they lack a substomatal cavity. Similarities to true stomata include two modified epidermal cells with specialized cell walls that separate by cuticle deposition and respond to drying. Pseudostomata may be interpreted as modified stomata that suppressed substomatal cavity formation, which in turn eliminated pore development. However, clarification of the homology of pseudostomata and moss stomata will require genomic studies integrated with physiological and structural data. The studies described in this dissertation significantly advance our understanding of moss stomatal development and structure, and provide a comparison point to better evaluate the evolution of stomata. Moss capsule anatomy coupled with the exclusive existence of stomata on capsules supports the concept that stomata in moss are involve in gas exchange but also facilitate drying and dispersal of spores. Changes in wall architecture coupled with a decrease in total pectin explain the inability of mature stomata to move. Development and distribution of stomata in Funaria provides evidence of a direct and less elaborated mechanism for stomatal development than described in Arabidopsis. Resolving relationships among early land plants, especially hornworts and mosses, the only bryophyte groups with stomata, is critical to understanding stomata evolution. Evaluated together, the results of this dissertation are consistent with a single origin of stomata in land plants.
3

Role of basement membranes and their break-down in human carcinomas:a study by <em>in situ</em> hybridization and immunohistochemistry of the expression of laminin chains, matrix metalloproteinases (MMPs) and their tissue inhibitors of metalloproteinases (TIMPs)

Määttä, M. (Marko) 19 October 2000 (has links)
Abstract In malignancies many alterations involving matrix macromolecule synthesis, secretion and assembly into basement membranes (BMs) as well as their degradation are present. The most important groups associated with matrix turnover are matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). In this study altogether 285 tissue samples were investigated comprising various malignant epithelial tumors and normal tissue structures, in which the distribution of different laminin chains was studied immunohistochemically. Laminin α5, β1 and γ1 were detected almost in all the BMs studied including normal tissues and malignancies, whereas α1 chain of laminin was present only in certain BMs. Laminin γ2 chain was solely expressed by epithelial BMs and was present in intracellular space especially in individual carcinoma cells infiltrating in the tumor stroma and in tumor cells in close contact with BM zone. Generally epithelial tumors contained quite well-formed BMs around their tumor clusters, except for infiltrative breast carcinoma and diffuse type gastric carcinoma. In situ hybridization revealed that only epithelial cells contained mRNAs for laminin α1 and γ2 chains, whereas laminin β1 chain and α1(IV) collagen were synthesized mainly by stromal cells. mRNA for MMP-2 was produced mainly by stromal cells in hepatocellular carcinoma of liver (HCC) and pancreatic adenocarcinoma, whereas MMP-9 and MT1-MMP were equally synthesized by carcinoma cells and cells of tumor stroma. However, in HCCs of grade III carcinoma cells predominated in their MT1-MMP expression. All three MMPs were immunolocalized to malignant epithelial cells and showed variably stromal cell positivity. Statistically mRNA synthesis for MT1-MMP was significantly associated with the shortened survival of patients with HCC (P ≤ 0.01). TIMP-1-3 mRNA, and especially TIMP-3, expressions in normal endometrium were significantly increased in endometrial stromal cells towards the secretory phase. In various endometrial hyperplasias TIMPs and MT1-MMP expressions were quite comparable to those seen in proliferating endometrium. In endometrial adenocarcinomas their expressions were significantly increased and the most intensified mRNA expressions were seen in grade III adenocarcinomas. Especially TIMP-3 and MT1-MMP mRNAs were synthesized by carcinoma cells. The results indicate that epithelial malignancies are capable of active synthesis and assembly of BM macromolecules. Simultaneous matrix synthesis and degradation seen in malignancies suggest that the mechanisms involved in matrix turnover are not lost during malignant transformation. mRNA synthesis for MMPs and TIMPs is generally increased in epithelial malignancies. The results therefore strongly support the concept that MMPs have an active role in carcinoma cell invasion.
4

Desenvolvimento estrutural e dinâmica de constituintes químicos no gineceu de Billbergia Nutans H.Wendl ex Regel (Bromelioideae-Bromeliaceae)

Fagundes, Natividad Ferreira January 2013 (has links)
No gineceu, ocorre o desenvolvimento de esporos e de gametófitos femininos no ovário, e as várias especializações do gineceu promovem sua interação com o gametófito masculino até a fecundação. Pouco se conhece sobre essas interações na porção ovariana do gineceu. Em Bromeliaceae, o detalhamento histológico do estigma e do estilete é inexistente. Para Billbergia, não existem dados embriológicos. Billbergia nutans (Bromeliaceae, Poales) é uma espécie importante como fonte de alimento para os polinizadores durante o inverno e apresenta ameaça de extinção em nível estadual. Este estudo visa ampliar o conhecimento sobre as modificações histológicas do gineceu em angiospermas, em preparação à polinização e fecundação; contribuir para o conhecimento da embriologia de Bromeliaceae; e verificar a presença de limitações ou vantagens reprodutivas durante o desenvolvimento embriológico de B. nutans. As análises foram executadas em Microscopia de Luz, em campo claro e epifluorescência, e em Microscopia Eletrônica de Varredura. Foram realizados testes histoquímicos e a marcação com anticorpos monoclonais para a detecção de compostos químicos. São registrados dados inéditos sobre a embriologia do gênero, a estrutura histológica do gineceu na família, a reconstrução tridimensional do gametófito feminino em monocotiledôneas e a imunolocalização de determinadas pectinas no ovário de angiospermas. A arquitetura do estigma espiral-conduplicado resulta de vários eventos ao longo do desenvolvimento. Os tricomas estigmáticos, o tecido transmissor e o obturador produzem secreção polissacarídica. Os tricomas estigmáticos armazenam sua secreção em bolsões pécticos no interior da parede periclinal externa. As paredes celulares labirínticas caracterizam as células do tecido transmissor e obturador de B. nutans como células de transferência, de composição pecto-celulósica. Há uma dinâmica de amido associada à secreção no gineceu, regulada pelo desenvolvimento. Os grãos de amido são considerados como fonte de moléculas para a produção da secreção, e os inúmeros campos primários de pontoação devem facilitar esse transporte. O obturador de Bromeliaceae é semelhante ao de espécies de Liliaceae e Asparagaceae. Os rudimentos seminais de Bromeliaceae são anátropos, bitegumentados e crassinucelados, com gametófito do tipo Polygonum. Muitos caracteres são sugeridos como úteis para a taxonomia da família. A morfologia do apêndice calazal pode ser um caráter inapropriado para aplicação taxonômica, devido à variabilidade encontrada em B. nutans. Quanto à evolução do rudimento seminal em Bromeliaceae, a subfamília que divergiu mais cedo mostra estados reduzidos de vários caracteres. Alguns caracteres parecem ser homoplásicos na família, podendo ser relevantes se aplicados em níveis taxonômicos inferiores. Em Poales, os tegumentos compostos por duas camadas celulares e o reduzido número de rudimentos seminais são, provavelmente, estados de caráter plesiomórficos. Não foram observadas limitações reprodutivas significativas durante o desenvolvimento do rudimento seminal de B. nutans. A modulação espacial encontrada entre arabinanos, galactanos e proteínas arabinogalactanos (AGPs) no ovário demarca a trajetória porogâmica do tubo polínico em direção ao gametófito feminino. A produção dessas moléculas é regulada pelo desenvolvimento. Possíveis funções das pectinas e AGPs nesses tecidos são discutidas, como a flexibilidade e expansibilidade da parede celular, sinalização e adesão celular, nutrição e atração do tubo polínico. A detecção química dessa trajetória tem sido observada em outras angiospermas, principalmente com relação às AGPs. Contudo, cada espécie possui um conjunto específico de moléculas, aparentemente não relacionado à posição filogenética. Este estudo mostra que o tubo polínico, possivelmente, aproxima-se do rudimento seminal por sinais direcionais sucessivos do gineceu. / In the gynoecium, the development of spores and female gametophytes occurs within the ovary, and the various specializations of the gynoecium promote its interaction with the male gametophyte until fertilization. Little is known about these interactions in the ovarian portion of the gynoecium. In Bromeliaceae, the histological detailing of the stigma and style is unknown. There are no embryological data for Billbergia. Billbergia nutans (Bromeliaceae, Poales) is an important species as a source of food for pollinators during winter and is under threat of extinction at the state level. This study aims to expand the knowledge about the histological changes of the gynoecium in preparation for pollination and fertilization in angiosperms; to contribute to knowledge of the embryology of Bromeliaceae; and to verify the presence of reproductive limitations or advantages in the embryological development of B. nutans. The analyses were performed with Light Microscopy, under bright field and epifluorescence, and in Scanning Electron Microscopy. Histochemical tests and labelling with monoclonal antibodies were performed for the detection of chemical components. Unpublished data are recorded on the embryology of the genus, the histological structure of the gynoecium in the family, the three-dimensional reconstruction of the female gametophyte in monocotyledons and the immunolocalization of certain pectins in the ovary of angiosperms. The architecture of the conduplicate-spiral stigma results from several events throughout the development. The stigmatic trichomes, the transmitting tissue and the obturator produce a polysaccharidic secretion. The stigmatic trichomes store the secretion in pectic pockets inside its outer periclinal wall. The labyrinthic cell walls are composed by cellulose and pectins and characterize the cells of the transmitting tissue and obturator of B. nutans as transfer cells. Starch dynamics associated with secretion are observed in the gynoecium, and are developmentally regulated. The starch grains are considered as a source of molecules for the production of secretion and many primary pit fields may facilitate such transport. The obturator of Bromeliaceae is similar to those of Liliaceae and Asparagaceae species. The ovules of Bromeliaceae are anatropous, bitegmic and crassinucellate, with a Polygonum-type gametophyte. Many characters are suggested as useful for the taxonomy of the family. The morphology of the chalazal appendage may not be an appropriate character for taxonomic use, due to the variability found in B. nutans. Regarding the evolution of the ovule in Bromeliaceae, the earliest-divergent subfamily shows a reduced state of several characters. Some characters appear homoplasious in the family and may be relevant when applied to lower taxonomic levels. Within Poales, the two-layered integuments and the small number of ovules are probably plesiomorphic character states. Reproductive limitations during ovule development of B. nutans were not found to be significant. The spatial modulation found between arabinan, galactan and arabinogalactan proteins (AGPs) in the ovary delineates the porogamic pollen tube pathway into the female gametophyte. The production of these molecules is developmentally regulated. Possible roles for pectins and AGPs in these tissues are discussed, such as the flexibility and expansibility of the cell wall, cell signaling, cell adhesion, nutrition and attraction of the pollen tube. The chemical detection of this pathway has been observed in other angiosperms, especially with respect to AGPs. However, each species has a specific set of molecules, apparently unrelated to the phylogenetic position. This study shows that the pollen tube possibly approaches the ovule by successive directional cues from the gynoecium.
5

Desenvolvimento estrutural e dinâmica de constituintes químicos no gineceu de Billbergia Nutans H.Wendl ex Regel (Bromelioideae-Bromeliaceae)

Fagundes, Natividad Ferreira January 2013 (has links)
No gineceu, ocorre o desenvolvimento de esporos e de gametófitos femininos no ovário, e as várias especializações do gineceu promovem sua interação com o gametófito masculino até a fecundação. Pouco se conhece sobre essas interações na porção ovariana do gineceu. Em Bromeliaceae, o detalhamento histológico do estigma e do estilete é inexistente. Para Billbergia, não existem dados embriológicos. Billbergia nutans (Bromeliaceae, Poales) é uma espécie importante como fonte de alimento para os polinizadores durante o inverno e apresenta ameaça de extinção em nível estadual. Este estudo visa ampliar o conhecimento sobre as modificações histológicas do gineceu em angiospermas, em preparação à polinização e fecundação; contribuir para o conhecimento da embriologia de Bromeliaceae; e verificar a presença de limitações ou vantagens reprodutivas durante o desenvolvimento embriológico de B. nutans. As análises foram executadas em Microscopia de Luz, em campo claro e epifluorescência, e em Microscopia Eletrônica de Varredura. Foram realizados testes histoquímicos e a marcação com anticorpos monoclonais para a detecção de compostos químicos. São registrados dados inéditos sobre a embriologia do gênero, a estrutura histológica do gineceu na família, a reconstrução tridimensional do gametófito feminino em monocotiledôneas e a imunolocalização de determinadas pectinas no ovário de angiospermas. A arquitetura do estigma espiral-conduplicado resulta de vários eventos ao longo do desenvolvimento. Os tricomas estigmáticos, o tecido transmissor e o obturador produzem secreção polissacarídica. Os tricomas estigmáticos armazenam sua secreção em bolsões pécticos no interior da parede periclinal externa. As paredes celulares labirínticas caracterizam as células do tecido transmissor e obturador de B. nutans como células de transferência, de composição pecto-celulósica. Há uma dinâmica de amido associada à secreção no gineceu, regulada pelo desenvolvimento. Os grãos de amido são considerados como fonte de moléculas para a produção da secreção, e os inúmeros campos primários de pontoação devem facilitar esse transporte. O obturador de Bromeliaceae é semelhante ao de espécies de Liliaceae e Asparagaceae. Os rudimentos seminais de Bromeliaceae são anátropos, bitegumentados e crassinucelados, com gametófito do tipo Polygonum. Muitos caracteres são sugeridos como úteis para a taxonomia da família. A morfologia do apêndice calazal pode ser um caráter inapropriado para aplicação taxonômica, devido à variabilidade encontrada em B. nutans. Quanto à evolução do rudimento seminal em Bromeliaceae, a subfamília que divergiu mais cedo mostra estados reduzidos de vários caracteres. Alguns caracteres parecem ser homoplásicos na família, podendo ser relevantes se aplicados em níveis taxonômicos inferiores. Em Poales, os tegumentos compostos por duas camadas celulares e o reduzido número de rudimentos seminais são, provavelmente, estados de caráter plesiomórficos. Não foram observadas limitações reprodutivas significativas durante o desenvolvimento do rudimento seminal de B. nutans. A modulação espacial encontrada entre arabinanos, galactanos e proteínas arabinogalactanos (AGPs) no ovário demarca a trajetória porogâmica do tubo polínico em direção ao gametófito feminino. A produção dessas moléculas é regulada pelo desenvolvimento. Possíveis funções das pectinas e AGPs nesses tecidos são discutidas, como a flexibilidade e expansibilidade da parede celular, sinalização e adesão celular, nutrição e atração do tubo polínico. A detecção química dessa trajetória tem sido observada em outras angiospermas, principalmente com relação às AGPs. Contudo, cada espécie possui um conjunto específico de moléculas, aparentemente não relacionado à posição filogenética. Este estudo mostra que o tubo polínico, possivelmente, aproxima-se do rudimento seminal por sinais direcionais sucessivos do gineceu. / In the gynoecium, the development of spores and female gametophytes occurs within the ovary, and the various specializations of the gynoecium promote its interaction with the male gametophyte until fertilization. Little is known about these interactions in the ovarian portion of the gynoecium. In Bromeliaceae, the histological detailing of the stigma and style is unknown. There are no embryological data for Billbergia. Billbergia nutans (Bromeliaceae, Poales) is an important species as a source of food for pollinators during winter and is under threat of extinction at the state level. This study aims to expand the knowledge about the histological changes of the gynoecium in preparation for pollination and fertilization in angiosperms; to contribute to knowledge of the embryology of Bromeliaceae; and to verify the presence of reproductive limitations or advantages in the embryological development of B. nutans. The analyses were performed with Light Microscopy, under bright field and epifluorescence, and in Scanning Electron Microscopy. Histochemical tests and labelling with monoclonal antibodies were performed for the detection of chemical components. Unpublished data are recorded on the embryology of the genus, the histological structure of the gynoecium in the family, the three-dimensional reconstruction of the female gametophyte in monocotyledons and the immunolocalization of certain pectins in the ovary of angiosperms. The architecture of the conduplicate-spiral stigma results from several events throughout the development. The stigmatic trichomes, the transmitting tissue and the obturator produce a polysaccharidic secretion. The stigmatic trichomes store the secretion in pectic pockets inside its outer periclinal wall. The labyrinthic cell walls are composed by cellulose and pectins and characterize the cells of the transmitting tissue and obturator of B. nutans as transfer cells. Starch dynamics associated with secretion are observed in the gynoecium, and are developmentally regulated. The starch grains are considered as a source of molecules for the production of secretion and many primary pit fields may facilitate such transport. The obturator of Bromeliaceae is similar to those of Liliaceae and Asparagaceae species. The ovules of Bromeliaceae are anatropous, bitegmic and crassinucellate, with a Polygonum-type gametophyte. Many characters are suggested as useful for the taxonomy of the family. The morphology of the chalazal appendage may not be an appropriate character for taxonomic use, due to the variability found in B. nutans. Regarding the evolution of the ovule in Bromeliaceae, the earliest-divergent subfamily shows a reduced state of several characters. Some characters appear homoplasious in the family and may be relevant when applied to lower taxonomic levels. Within Poales, the two-layered integuments and the small number of ovules are probably plesiomorphic character states. Reproductive limitations during ovule development of B. nutans were not found to be significant. The spatial modulation found between arabinan, galactan and arabinogalactan proteins (AGPs) in the ovary delineates the porogamic pollen tube pathway into the female gametophyte. The production of these molecules is developmentally regulated. Possible roles for pectins and AGPs in these tissues are discussed, such as the flexibility and expansibility of the cell wall, cell signaling, cell adhesion, nutrition and attraction of the pollen tube. The chemical detection of this pathway has been observed in other angiosperms, especially with respect to AGPs. However, each species has a specific set of molecules, apparently unrelated to the phylogenetic position. This study shows that the pollen tube possibly approaches the ovule by successive directional cues from the gynoecium.
6

Desenvolvimento estrutural e dinâmica de constituintes químicos no gineceu de Billbergia Nutans H.Wendl ex Regel (Bromelioideae-Bromeliaceae)

Fagundes, Natividad Ferreira January 2013 (has links)
No gineceu, ocorre o desenvolvimento de esporos e de gametófitos femininos no ovário, e as várias especializações do gineceu promovem sua interação com o gametófito masculino até a fecundação. Pouco se conhece sobre essas interações na porção ovariana do gineceu. Em Bromeliaceae, o detalhamento histológico do estigma e do estilete é inexistente. Para Billbergia, não existem dados embriológicos. Billbergia nutans (Bromeliaceae, Poales) é uma espécie importante como fonte de alimento para os polinizadores durante o inverno e apresenta ameaça de extinção em nível estadual. Este estudo visa ampliar o conhecimento sobre as modificações histológicas do gineceu em angiospermas, em preparação à polinização e fecundação; contribuir para o conhecimento da embriologia de Bromeliaceae; e verificar a presença de limitações ou vantagens reprodutivas durante o desenvolvimento embriológico de B. nutans. As análises foram executadas em Microscopia de Luz, em campo claro e epifluorescência, e em Microscopia Eletrônica de Varredura. Foram realizados testes histoquímicos e a marcação com anticorpos monoclonais para a detecção de compostos químicos. São registrados dados inéditos sobre a embriologia do gênero, a estrutura histológica do gineceu na família, a reconstrução tridimensional do gametófito feminino em monocotiledôneas e a imunolocalização de determinadas pectinas no ovário de angiospermas. A arquitetura do estigma espiral-conduplicado resulta de vários eventos ao longo do desenvolvimento. Os tricomas estigmáticos, o tecido transmissor e o obturador produzem secreção polissacarídica. Os tricomas estigmáticos armazenam sua secreção em bolsões pécticos no interior da parede periclinal externa. As paredes celulares labirínticas caracterizam as células do tecido transmissor e obturador de B. nutans como células de transferência, de composição pecto-celulósica. Há uma dinâmica de amido associada à secreção no gineceu, regulada pelo desenvolvimento. Os grãos de amido são considerados como fonte de moléculas para a produção da secreção, e os inúmeros campos primários de pontoação devem facilitar esse transporte. O obturador de Bromeliaceae é semelhante ao de espécies de Liliaceae e Asparagaceae. Os rudimentos seminais de Bromeliaceae são anátropos, bitegumentados e crassinucelados, com gametófito do tipo Polygonum. Muitos caracteres são sugeridos como úteis para a taxonomia da família. A morfologia do apêndice calazal pode ser um caráter inapropriado para aplicação taxonômica, devido à variabilidade encontrada em B. nutans. Quanto à evolução do rudimento seminal em Bromeliaceae, a subfamília que divergiu mais cedo mostra estados reduzidos de vários caracteres. Alguns caracteres parecem ser homoplásicos na família, podendo ser relevantes se aplicados em níveis taxonômicos inferiores. Em Poales, os tegumentos compostos por duas camadas celulares e o reduzido número de rudimentos seminais são, provavelmente, estados de caráter plesiomórficos. Não foram observadas limitações reprodutivas significativas durante o desenvolvimento do rudimento seminal de B. nutans. A modulação espacial encontrada entre arabinanos, galactanos e proteínas arabinogalactanos (AGPs) no ovário demarca a trajetória porogâmica do tubo polínico em direção ao gametófito feminino. A produção dessas moléculas é regulada pelo desenvolvimento. Possíveis funções das pectinas e AGPs nesses tecidos são discutidas, como a flexibilidade e expansibilidade da parede celular, sinalização e adesão celular, nutrição e atração do tubo polínico. A detecção química dessa trajetória tem sido observada em outras angiospermas, principalmente com relação às AGPs. Contudo, cada espécie possui um conjunto específico de moléculas, aparentemente não relacionado à posição filogenética. Este estudo mostra que o tubo polínico, possivelmente, aproxima-se do rudimento seminal por sinais direcionais sucessivos do gineceu. / In the gynoecium, the development of spores and female gametophytes occurs within the ovary, and the various specializations of the gynoecium promote its interaction with the male gametophyte until fertilization. Little is known about these interactions in the ovarian portion of the gynoecium. In Bromeliaceae, the histological detailing of the stigma and style is unknown. There are no embryological data for Billbergia. Billbergia nutans (Bromeliaceae, Poales) is an important species as a source of food for pollinators during winter and is under threat of extinction at the state level. This study aims to expand the knowledge about the histological changes of the gynoecium in preparation for pollination and fertilization in angiosperms; to contribute to knowledge of the embryology of Bromeliaceae; and to verify the presence of reproductive limitations or advantages in the embryological development of B. nutans. The analyses were performed with Light Microscopy, under bright field and epifluorescence, and in Scanning Electron Microscopy. Histochemical tests and labelling with monoclonal antibodies were performed for the detection of chemical components. Unpublished data are recorded on the embryology of the genus, the histological structure of the gynoecium in the family, the three-dimensional reconstruction of the female gametophyte in monocotyledons and the immunolocalization of certain pectins in the ovary of angiosperms. The architecture of the conduplicate-spiral stigma results from several events throughout the development. The stigmatic trichomes, the transmitting tissue and the obturator produce a polysaccharidic secretion. The stigmatic trichomes store the secretion in pectic pockets inside its outer periclinal wall. The labyrinthic cell walls are composed by cellulose and pectins and characterize the cells of the transmitting tissue and obturator of B. nutans as transfer cells. Starch dynamics associated with secretion are observed in the gynoecium, and are developmentally regulated. The starch grains are considered as a source of molecules for the production of secretion and many primary pit fields may facilitate such transport. The obturator of Bromeliaceae is similar to those of Liliaceae and Asparagaceae species. The ovules of Bromeliaceae are anatropous, bitegmic and crassinucellate, with a Polygonum-type gametophyte. Many characters are suggested as useful for the taxonomy of the family. The morphology of the chalazal appendage may not be an appropriate character for taxonomic use, due to the variability found in B. nutans. Regarding the evolution of the ovule in Bromeliaceae, the earliest-divergent subfamily shows a reduced state of several characters. Some characters appear homoplasious in the family and may be relevant when applied to lower taxonomic levels. Within Poales, the two-layered integuments and the small number of ovules are probably plesiomorphic character states. Reproductive limitations during ovule development of B. nutans were not found to be significant. The spatial modulation found between arabinan, galactan and arabinogalactan proteins (AGPs) in the ovary delineates the porogamic pollen tube pathway into the female gametophyte. The production of these molecules is developmentally regulated. Possible roles for pectins and AGPs in these tissues are discussed, such as the flexibility and expansibility of the cell wall, cell signaling, cell adhesion, nutrition and attraction of the pollen tube. The chemical detection of this pathway has been observed in other angiosperms, especially with respect to AGPs. However, each species has a specific set of molecules, apparently unrelated to the phylogenetic position. This study shows that the pollen tube possibly approaches the ovule by successive directional cues from the gynoecium.
7

Caracterização estrutural e funcional de septinas de Schistosoma mansoni / Structural and functional characterization of Schistosoma mansoni septins

Zeraik, Ana Eliza 23 October 2013 (has links)
Septinas são proteínas pertencentes à família das GTPases que estão envolvidas em uma variedade de funções celulares. Verificamos através de análises bioinformáticas que Schistosoma mansoni, um dos principais agentes etiológicos da esquistossomose, possui quatro genes que codificam septinas (SmSept5, SmSept10, SmSept7.1 e SmSept7.2). O objetivo deste trabalho foi a produção heteróloga das proteínas codificadas por estes genes, visando estudos estruturais e funcionais das mesmas. As septinas SmSEPT5 e SmSEPT10 foram expressas em sistema recombinante e foi possível a obtenção de formas solúveis destas proteínas. Experimentos de gel filtração e cross-linking mostraram que elas são diméricas em solução e estáveis em ampla faixa de pH, embora agregados proteicos tenham sido observados com o aumento da temperatura. Ambas as proteínas foram capazes de ligar GTP e GDP, embora apenas SmSEPT5 tenha apresentado atividade GTPásica. Mg2+ se mostrou essencial para a ligação de GTP a ambas as proteínas, enquanto a ligação do GDP foi independente da presença deste cofator. Ensaios de cristalização com o domínio GTPase de SmSEPT10 resultaram em cristais de ótima qualidade cuja difração resultou na obtenção da estrutura com melhor resolução alcançada até o momento para septinas: 1.9 &Aring; para a forma ligada a GDP e 2.1 &Aring; para a forma ligada a GTP. A análise da sobreposição das estruturas obtidas resultou na observação do deslizamento de uma fita &beta; em relação às demais, que acreditamos estar envolvido com o mecanismo de associação destas proteínas à membranas. Um sistema de coexpressão foi construído em que SmSEPT5, SmSEPT10 e SmSEPT7.2 foram coexpressas e copurificadas, resultando na verificação da formação de hetero-oligômeros e filamentos por estas proteínas. Tratamento de diversas fases do ciclo de vida do parasito com um composto (FCF) que afeta a dinâmica de filamentos de septina, resultou em um fenótipo reversível de paralisia no parasito. Estudos de imunolocalização revelaram a colocalização de septinas e actina em fibras musculares do parasito, sugerindo que a interação entre filamentos de septina e actina pode ter um papel importante nas funções motoras do parasita. A imunolocalização revelou ainda a presença de septinas em placas epiteliais ciliadas de miracídios, células germinativas de miracídios e esporocistos e protonefrídios de cercárias. Os resultados apresentados aqui constituem a primeira descrição de septinas em platelmintos e nos possibilitam o estabelecimento de correlações estruturais e funcionais entre septinas de S. mansoni e complexos análogos de septinas de outros organismos, contribuindo para a elucidação da função desta família de proteínas. / Septins belong to the GTPase family of proteins and are involved in a variety of cellular processes. We have identified four genes encoding septins in Schistosoma mansoni, one of the main causative agents of schistosomiasis, these genes were named SmSept5, SmSept10, SmSept7.1 e SmSept7.2. The aim of this study was to clone the cDNA of these genes in order to subject the resulting proteins to a set of biophysical and functional studies. Biophysical characterizations were undertaken with SmSEPT5 and SmSEPT10 because of the higher solubility of these proteins, which were dimeric in solution and stable over a wide range of pH, although increasing temperatures promoted the aggregation of these proteins. The nucleotide binding assays revealed that both were capable of binding GTP and GDP, although only SmSEPT5 presented GTPase activity. Mg2+ has shown to be essential for GTP binding in both proteins while GDP binding was independent of this cofactor. Crystallization assays with the GTPase domain of SmSEPT10 have resulted in crystals of high quality and consequently high resolution structures were obtained: 1.9 &Aring; to the GDP bound form and 2.1 &Aring; to the GTP bound form, the best resolution achieved to date for any septin member. The sobreposition of the structures obtained enabled us to observe a strand slippage in &beta;3 strand suggesting that it might be part of an activation mechanism involved in the association of these proteins to membranes. A coexpression system was produced, in which SmSEPT5, SmSEPT10 and SmSEPT7.2 were coexpressed and copurified. These proteins were able to assemble into heterocomplexes that further polymerize into filaments. Functional studies performed with a drug (FCF) that affects the dynamics of septin filaments have resulted in a reversible paralysis phenotype in the parasite. Immunolocalization experiments revealed the colocalization of septins and actin in muscular structures of the parasite, suggesting that the interaction of septin and actin filaments might have an important role in the motor activity of the parasite. The immunolocalization also revealed the presence of septins in the ephitelial plates of miracidia, germ cells of miracidia and sporocysts and protonephridia of cercariae. The results presented here constitute the first description of septins in phatyhelmintes and enabled us the establishment of structural and functional relaltionships among septins from S. mansoni and analogous septin complexes in other organisms, contributing to elucidate the function of this family of proteins.
8

Sazonalidade reprodutiva em machos de tartaruga (Kinosternon scorpioides) de vida livre no Nordeste brasileiro evidenciado por imunolocalização de enzimas esteroidogênicas no testículo e epidídimo / Reproductive seasonality in male turtles (Kinosternon scorpioides) of free life in Northeast Brazil evidenced by immunolocalization of steroidogenic enzymes in the testis and epididymis

Viana, Diego Carvalho 09 March 2016 (has links)
No Estado do Maranhão, na região da Baixada Maranhense, presenta na fauna silvestre o réptil Kinosternon scorpioides, um quelônio de água doce popularmente conhecido como jurará e que possui valor social, econômico e ambiental para os ribeirinhos da cidade de São Bento. Este estudo contempla suas características biológicas reprodutivas baseadas em seu ambiente natural, com o intuito de permitir a preservação e o estabelecimento de planos de manejo reprodutivo e de uso sustentável da espécie. Recentemente poucos estudos em todo o mundo tratam sobre os aspectos do ciclo reprodutivo de tartarugas em face das características endócrinas, na América do Sul estudos desse tipo são recentes e escassos, sendo assim este é o primeiro estudo, que se tem conhecimento, que elucida um padrão sazonal reprodutivo da espécie K. scorpioides, associando hormônios gonadais com aspectos comportamentais. Trinta e oito animais adultos tiveram seus órgãos reprodutivos caracterizados para as enzimas esteroidogênicas P450 aromatase, P450c17 e PNADPH redutase através de imunomarcação e blotting, além de índice gonadossomático, morfometria e concentração de testosterona, corticosterona e estradiol pela técnica de radioimunoensaio. As mudanças biométricas, morfometria celular e a esteroidogênese testicular entre os períodos chuvoso e seco sugerem que o estrógeno produzido pelas células de leydig podem afetar a produção e a apoptose de células germinais durante o processo de espermatogênese, e a presença das enzimas P450aromatase e P450c17 em células de leydig acompanhados com a recrudescência testicular também reforça a ideia, de que elas podem desempenhar um papel na quiescência testicular. Esse trabalho evidenciou que as enzimas citocromo P450, citocromo P450c17 e NADPH-citocromo P450-redutase estão presentes no testículo e epidídimo nos diferentes períodos climáticos e podem estar relacionados à síntese de testosterona em tartarugas concordando com os diferentes achados para biometria e espermiogênese nos períodos chuvoso e seco, o que, nos leva a sugerir um estado de quiescência durante o período seco e atividade espermatogênica no período chuvoso, semelhante ao que ocorre com as espécies que apresentam comportamento reprodutivo sazonal / In the state of Maranhão, in the lowland region, the reptile Kinosternon scorpioides, a freshwater chelonian, popularly known as swear has social, economic and environmental value to the riparian of the city of São Bento. This study includes reproductive biological characteristics based on their natural environment in order to enable the preservation and the establishment of reproductive management plans and sustainable use of the species. To date, few studies around the world address the aspects of the reproductive cycle of the turtles in the face of the endocrine features. In South America, these studies are recent and scarce. So this is the first study that elucidates a reproductive seasonal pattern of the species K. scorpioides, by associating gonadal hormones with behavioral aspects. Thirty-eight adult animals had their reproductive organs characterized for P450 steroidogenic enzyme aromatase, P450c17 and NADPH reductase by immunostaining and immunoblotting, and gonadossomatic index, morphology and concentration of testosterone, corticosterone and estradiol by radioimmunoassay. Biometric changes, cell morphology and testicular steroidogenesis between the rainy and dry seasons suggests that the estrogen produced by the leydig cells can affect the production and apoptosis of germ cells during spermatogenesis process; and the presence of P450aromatase and P450c17 enzymes in the leydig cells accompanied with testicular recrudescence also reinforces the idea that they may play a role in testicular quiescence. This work showed that the cytochrome P450 enzymes, P450c17 and NADPH-cytochrome P450 reductase are present in the testis and epididymis at different climatic periods and may be related to testosterone synthesis in turtles agreeing to the different findings for biometrics and spermiogenesis in and dry rainy periods. These findings suggest a state of quiescence during the dry season and spermatogenic activity during the rainy season, similar to those found in species with seasonal reproductive behavior
9

Utilisation de la cryoconservation pour la conservation et la production de cultures in vitro de palmier dattier (Phoenix dactylifera L.) : Impact d'un protocole de cryoconservation sur la physiologie des cals embryogènes de palmier dattier / Use of cryopreservation for the conservation and production of date palm (Phoenix dactylifera L.) in vitro cultures : Impact of a cryopreservation protocol on the physiology of embryogenic callus of date palm

Salma, Mohammad 08 December 2015 (has links)
Le palmier dattier (Phoenix dactylifera L.) a une grande importance écologique et socio-économique dans les zones arides et semi-arides du globe. Cette espèce présente une grande diversité (plus de 2.000 variétés identifiées) qui est menacée par la production à grande échelle de variétés élites. Il est nécessaire de développer des techniques permettant de conserver cette diversité et de gérer la production des variétés élites multipliées in vitro. La cryoconservation (azote liquide, -196°C) est la seule technique disponible à l’heure actuelle permettant la conservation à long terme, à coûts réduits et en sécurité de cette diversité. Dans ce travail, nous avons comparé l’efficacité de deux techniques de cryoconservation, la vitrification en goutte (DV) et la D cryo-plate (DP), pour la cryoconservation de masses proembryogènes (PEM) de deux variétés de palmier dattier, Sokary et Sultany. Avec la DV, la survie des PEM cryoconservées est nulle sans prétraitement au saccharose (3 jours avec 0,5M) et sans traitement avec la solution de vitrification PVS2. Après 15 à 120 min de traitement avec PVS2, la survie est comprise entre 90,9-98,6% et 85,6-88,0%, respectivement pour Sokary et Sultany. Avec un prétraitement au saccharose, 21,1% des PEM de la variété Sokary survivent à la cryoconservation sans traitement avec PVS2. Avec la DP, un effet positif du prétraitement au saccharose est observé sur la survie des PEM cryoconservés. Pour Sokary, la survie la plus importante (de 92,0 à 95,8%) après congélation est obtenue pour des durées de dessiccation comprises entre 60 et 120 min. La survie après cryoconservation est comprise entre 67,0 et 74,6% après des durées de 90 à 120 min de dessiccation pour Sultany. Avec les deux techniques expérimentées, l'intensité de croissance des PEM cryoconservées est supérieure chez Sokary par rapport à Sultany. L’étude histologique réalisée montre qu’en l’absence de prétraitement, c'est le traitement de loading qui induit la plasmolyse des cellules la plus importante, d'environ 26, 40 et 50%, respectivement pour les cellules méristématiques, les cellules embryogènes de la population I (PopI) et de la population II (PopII) par rapport à leur état initial. Le prétraitement au saccharose induit une plasmolyse d'environ 50% uniquement chez les cellules de PopII. Le traitement de loading et de vitrification n'entraîne pas de plasmolyse supplémentaire. Aucune plasmolyse n'est observée chez les cellules méristématiques et les cellules de PopI. En revanche, les mesures de la surface de l'ensemble des cellules montrent chez les cellules méristématiques une diminution significative de surface après le prétraitement au saccharose, mais aucune différence significative après le traitement de loading et de vitrification. Chez les cellules embryogènes de PopI, une diminution supplémentaire de la surface est observée après le traitement de vitrification. L’étude de la circularité des noyaux montre une déformation permanente des noyaux des cellules non prétraitées des trois types cellulaires, alors que seuls les noyaux des cellules de PopII présentent cet aspect chez les PEM prétraitées. Enfin, l'étude du degré de méthylation des PEM par immunolocalisation conclut à l'absence de différences significatives entre les PEM témoins non traitées et les autres conditions expérimentales. Cependant, les tissus différenciés présentent un pourcentage de noyaux méthylés plus important par rapport aux cellules embryogènes et aucun marquage n'est noté chez les cellules méristématiques. Nos résultats ont permis de préciser l’effet de la cryoconservation sur l’intégrité structurale et la physiologie des PEM de palmier dattier. Ils contribuent également à la sauvegarde de la biodiversité du palmier dattier. / The date palm (Phoenix dactylifera. L) has a great ecological and socioeconomic importance in arid and semi-arid areas of the globe. This species displays a great diversity, with over 2,000 identified varieties, which is threatened by the large scale production of elite varieties. It is necessary to develop techniques allowing to conserve this biodiversity and to manage the production of in vitro propagated elite varieties. Cryopreservation (liquid nitrogen [LN], -196°C) is currently the only technique available ensuring the safe and cost-effective long-term conservation of this diversity. In this work, we compared the efficiency of two cryopreservation techniques, droplet-vitrification (DV) and D cryo-plate (DP), for the cryopreservation of proembryonic masses (PEMs) of two varieties of date palm, Sokary and Sultany. With DV, recovery of cryopreserved PEMs was nil without sucrose pretreatment (3 days, 0.5 M) and without treatment with PVS2 vitrification solution. After 15 to 120 min of PVS2 treatment, recovery was between 90.9-98.6% and 85.6-88.0% for Sokary and Sultany, respectively. Sucrose pretreatment led to 21.1% recovery of cryopreserved PEMs of variety Sokary without PVS2 treatment. Regrowth intensity of PEMs cryopreserved was generally lower in the Sultany variety compared to the Sokary variety. With DP, a positive effect of sucrose pretreatment on recovery of cryopreserved PEMs was observed. For Sokary, the highest recovery of PEMs (92.0 to 95.8%) after LN exposure was achieved for desiccation periods between 60 and 120 min. Recovery of cryopreserved PEMs of variety Sultany was between 67.0 and 74.6% after desiccation periods between 90-120 min. With DP, the regrowth intensity of cryopreserved PEMs was higher for variety Sokary compared to Sultany. The histological study performed showed that in absence of pretreatment, it was the loading treatment which induced the highest cell plasmolysis, with values of 26, 40 and 50% for meristematic, embryogenic PopI and PopII cells, respectively, compared to their initial state. Sucrose pretreatment induced a 50% plasmolysis only in PopII cells. The loading and vitrification treatments did not cause any additional plasmolysis. No plasmolysis was observed in meristematic or PopI cells. By contrast, the measurement of the surface of all cells revealed a significant decrease in the surface of meristematic cells after pretreatment, but no significant difference after the loading or vitrification treatments. In embryogenic PopI cells, an additional decrease in the cell surface was observed after the PVS2 treatment. The study of nuclei circularity showed a permanent deformation of nuclei of non-pretreated cells of the three cell types. In pretreated PEMs, only the nuclei of PopII cells displayed deformation. Finally, the study of the methylation degree in PEMs by immunolocalization revealed the absence of significant differences between the untreated controls and other experimental conditions. However, the differentiated tissues exhibited a higher percentage of methylated nuclei compared to embryogenic cells, while no stained nuclei were observed in meristematic cells. Our results allowed clarifying the effect of cryopreservation on the structural integrity and on the physiology of date palm PEMs. They also contribute to safeguarding of date palm biodiversity.
10

Caracterização estrutural e funcional de septinas de Schistosoma mansoni / Structural and functional characterization of Schistosoma mansoni septins

Ana Eliza Zeraik 23 October 2013 (has links)
Septinas são proteínas pertencentes à família das GTPases que estão envolvidas em uma variedade de funções celulares. Verificamos através de análises bioinformáticas que Schistosoma mansoni, um dos principais agentes etiológicos da esquistossomose, possui quatro genes que codificam septinas (SmSept5, SmSept10, SmSept7.1 e SmSept7.2). O objetivo deste trabalho foi a produção heteróloga das proteínas codificadas por estes genes, visando estudos estruturais e funcionais das mesmas. As septinas SmSEPT5 e SmSEPT10 foram expressas em sistema recombinante e foi possível a obtenção de formas solúveis destas proteínas. Experimentos de gel filtração e cross-linking mostraram que elas são diméricas em solução e estáveis em ampla faixa de pH, embora agregados proteicos tenham sido observados com o aumento da temperatura. Ambas as proteínas foram capazes de ligar GTP e GDP, embora apenas SmSEPT5 tenha apresentado atividade GTPásica. Mg2+ se mostrou essencial para a ligação de GTP a ambas as proteínas, enquanto a ligação do GDP foi independente da presença deste cofator. Ensaios de cristalização com o domínio GTPase de SmSEPT10 resultaram em cristais de ótima qualidade cuja difração resultou na obtenção da estrutura com melhor resolução alcançada até o momento para septinas: 1.9 &Aring; para a forma ligada a GDP e 2.1 &Aring; para a forma ligada a GTP. A análise da sobreposição das estruturas obtidas resultou na observação do deslizamento de uma fita &beta; em relação às demais, que acreditamos estar envolvido com o mecanismo de associação destas proteínas à membranas. Um sistema de coexpressão foi construído em que SmSEPT5, SmSEPT10 e SmSEPT7.2 foram coexpressas e copurificadas, resultando na verificação da formação de hetero-oligômeros e filamentos por estas proteínas. Tratamento de diversas fases do ciclo de vida do parasito com um composto (FCF) que afeta a dinâmica de filamentos de septina, resultou em um fenótipo reversível de paralisia no parasito. Estudos de imunolocalização revelaram a colocalização de septinas e actina em fibras musculares do parasito, sugerindo que a interação entre filamentos de septina e actina pode ter um papel importante nas funções motoras do parasita. A imunolocalização revelou ainda a presença de septinas em placas epiteliais ciliadas de miracídios, células germinativas de miracídios e esporocistos e protonefrídios de cercárias. Os resultados apresentados aqui constituem a primeira descrição de septinas em platelmintos e nos possibilitam o estabelecimento de correlações estruturais e funcionais entre septinas de S. mansoni e complexos análogos de septinas de outros organismos, contribuindo para a elucidação da função desta família de proteínas. / Septins belong to the GTPase family of proteins and are involved in a variety of cellular processes. We have identified four genes encoding septins in Schistosoma mansoni, one of the main causative agents of schistosomiasis, these genes were named SmSept5, SmSept10, SmSept7.1 e SmSept7.2. The aim of this study was to clone the cDNA of these genes in order to subject the resulting proteins to a set of biophysical and functional studies. Biophysical characterizations were undertaken with SmSEPT5 and SmSEPT10 because of the higher solubility of these proteins, which were dimeric in solution and stable over a wide range of pH, although increasing temperatures promoted the aggregation of these proteins. The nucleotide binding assays revealed that both were capable of binding GTP and GDP, although only SmSEPT5 presented GTPase activity. Mg2+ has shown to be essential for GTP binding in both proteins while GDP binding was independent of this cofactor. Crystallization assays with the GTPase domain of SmSEPT10 have resulted in crystals of high quality and consequently high resolution structures were obtained: 1.9 &Aring; to the GDP bound form and 2.1 &Aring; to the GTP bound form, the best resolution achieved to date for any septin member. The sobreposition of the structures obtained enabled us to observe a strand slippage in &beta;3 strand suggesting that it might be part of an activation mechanism involved in the association of these proteins to membranes. A coexpression system was produced, in which SmSEPT5, SmSEPT10 and SmSEPT7.2 were coexpressed and copurified. These proteins were able to assemble into heterocomplexes that further polymerize into filaments. Functional studies performed with a drug (FCF) that affects the dynamics of septin filaments have resulted in a reversible paralysis phenotype in the parasite. Immunolocalization experiments revealed the colocalization of septins and actin in muscular structures of the parasite, suggesting that the interaction of septin and actin filaments might have an important role in the motor activity of the parasite. The immunolocalization also revealed the presence of septins in the ephitelial plates of miracidia, germ cells of miracidia and sporocysts and protonephridia of cercariae. The results presented here constitute the first description of septins in phatyhelmintes and enabled us the establishment of structural and functional relaltionships among septins from S. mansoni and analogous septin complexes in other organisms, contributing to elucidate the function of this family of proteins.

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