RESUMO
The present study investigated the dynamic on a short-time scale in the vegetation in moist grassland of the Sete Cidades National Park, Piauí. Herb-subshrub layer samples was carried out in July 2007, 2009 and 2011. Changes in structural, floristic and functional traits in the community were assessed by species richness, diversity and similarity indices between those periods, as well as by hierarchical classification and ordination. Cluster and Principal Component Analyses identified functional groups according to 23 species trait state. To distinguish the contribution of space and time configuration in the community structure, we used the variance partition technique. The functional groups of chamaephytes and therophytes II were associated with wetter sites, while the groups of non-tussock hemicriptophytes I, tussock hemicriptophytes (FG4), and geophytes (FG5) were associated to the drier ones. We found a non-accelerated dynamics, at least on a short-time scale, represented by some descriptors in the community, such as the close similarity between the inventories and ordering of sampling transects in moist grassland. Therefore, besides considering the partition of the temporal niche as a mechanism for the co-existence of species, the heterogeneity of space dictated by environmental filters seems to determine the stability of the this grassland communities over time.
Assuntos
Biodiversidade , Poaceae/classificação , Brasil , Dinâmica Populacional , Estações do Ano , Especificidade da EspécieRESUMO
The present study investigated the dynamic on a short-time scale in the vegetation in moist grassland of the Sete Cidades National Park, Piauí. Herb-subshrub layer samples was carried out in July 2007, 2009 and 2011. Changes in structural, floristic and functional traits in the community were assessed by species richness, diversity and similarity indices between those periods, as well as by hierarchical classification and ordination. Cluster and Principal Component Analyses identified functional groups according to 23 species trait state. To distinguish the contribution of space and time configuration in the community structure, we used the variance partition technique. The functional groups of chamaephytes and therophytes II were associated with wetter sites, while the groups of non-tussock hemicriptophytes I, tussock hemicriptophytes (FG4), and geophytes (FG5) were associated to the drier ones. We found a non-accelerated dynamics, at least on a short-time scale, represented by some descriptors in the community, such as the close similarity between the inventories and ordering of sampling transects in moist grassland. Therefore, besides considering the partition of the temporal niche as a mechanism for the co-existence of species, the heterogeneity of space dictated by environmental filters seems to determine the stability of the this grassland communities over time.(AU)
O presente estudo investigou a dinâmica em uma curta escala de tempo na vegetação de campo limpo úmido do Parque Nacional Sete Cidades Park, Piauí. Amostragens da camada herbáceo-subarbustiva foram realizadas em julho de 2007, 2009 e 2011. Mudanças estruturais, florísticas e de atributos funcionais da comunidade foram avaliadas por índices de riqueza de espécies, diversidade e similaridade entre esses períodos, bem como por classificação hierárquica e ordenação. Análise de Componentes Principais e de Cluster identificaram grupos funcionais de acordo com 23 atributos das espécies. Para distinguir a contribuição do espaço e do tempo nas análises, usamos técnicas de partição de variância. Os grupos funcionais das caméfitas e terófitas II foram associados com os locais mais úmidos, enquanto os grupos de hemicriptófitas I não entouceiradas, hemicriptófitos entouceiradas e das geófitas (GF5) foram associados aos mais secos. Nós encontramos uma dinâmica não-acelerada, pelo menos em uma escala de curta duração, representada por alguns descritores da comunidade, tais como a similaridade entre os inventários e a ordenação dos transectos no campo limpo úmido. Assim, além de considerar a partição do nicho temporal como um mecanismo para a coexistência de espécies, a heterogeneidade do espaço ditada por filtros ambientais parece determinar a estabilidade destas comunidades campestres ao longo do tempo.(AU)
Assuntos
Biodiversidade , Poaceae/classificação , Brasil , Dinâmica Populacional , Estações do Ano , Especificidade da EspécieRESUMO
Bone marrow is a heterogeneous cell population which includes hematopoietic and mesenchymal progenitor cells. Dysregulated hematopoiesis occurs in chronic myelogenous leukemia (CML), being caused at least in part by abnormalities in the hematopoietic progenitors. However, the role of mesenchymal stem cells (MSCs) in CML has not been well characterized. The objectives of the present study were to observe the biological characteristics of MSCs from CML patients and to determine if MSCs originate in part from donors in CML patients after bone marrow transplantation (BMT). We analyzed MSCs from 5 untreated patients and from 3 CML patients after sex-mismatched allogeneic BMT. Flow cytometry analysis revealed the typical MSC phenotype and in vitro assays showed ability to differentiate into adipocytes and osteoblasts. Moreover, although some RT-PCR data were contradictory, combined fluorescence in situ hybridization analysis showed that MSCs from CML patients do not express the bcr-abl gene. Regarding MSCs of donor origin, although it is possible to detect Y target sequence by nested PCR, the low frequency (0.14 and 0.34%) of XY cells in 2 MSC CML patients by fluorescence in situ hybridization analysis suggests the presence of contaminant hematopoietic cells and the absence of host-derived MSCs in CML patients. Therefore, we conclude that MSCs from CML patients express the typical MSC phenotype, can differentiate into osteogenic and adipogenic lineages and do not express the bcr-abl gene. MSCs cannot be found in recipients 12 to 20 months after BMT. The influence of MSCs on the dysregulation of hematopoiesis in CML patients deserves further investigation.
Assuntos
Transplante de Medula Óssea , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Células-Tronco Mesenquimais/química , Condicionamento Pré-Transplante , Adolescente , Adulto , Quimera , Feminino , Proteínas de Fusão bcr-abl/análise , Hematopoese , Humanos , Hibridização in Situ Fluorescente , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Masculino , Células-Tronco Mesenquimais/fisiologia , Pessoa de Meia-Idade , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de TempoRESUMO
Bone marrow is a heterogeneous cell population which includes hematopoietic and mesenchymal progenitor cells. Dysregulated hematopoiesis occurs in chronic myelogenous leukemia (CML), being caused at least in part by abnormalities in the hematopoietic progenitors. However, the role of mesenchymal stem cells (MSCs) in CML has not been well characterized. The objectives of the present study were to observe the biological characteristics of MSCs from CML patients and to determine if MSCs originate in part from donors in CML patients after bone marrow transplantation (BMT). We analyzed MSCs from 5 untreated patients and from 3 CML patients after sex-mismatched allogeneic BMT. Flow cytometry analysis revealed the typical MSC phenotype and in vitro assays showed ability to differentiate into adipocytes and osteoblasts. Moreover, although some RT-PCR data were contradictory, combined fluorescence in situ hybridization analysis showed that MSCs from CML patients do not express the bcr-abl gene. Regarding MSCs of donor origin, although it is possible to detect Y target sequence by nested PCR, the low frequency (0.14 and 0.34 percent) of XY cells in 2 MSC CML patients by fluorescence in situ hybridization analysis suggests the presence of contaminant hematopoietic cells and the absence of host-derived MSCs in CML patients. Therefore, we conclude that MSCs from CML patients express the typical MSC phenotype, can differentiate into osteogenic and adipogenic lineages and do not express the bcr-abl gene. MSCs cannot be found in recipients 12 to 20 months after BMT. The influence of MSCs on the dysregulation of hematopoiesis in CML patients deserves further investigation.