Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 13(1): 289, 2023 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609587

RESUMO

Recovery of depleted fish stocks is an important goal for fisheries management and crucial to sustain important ecosystem functions as well as global food security. Successful recovery requires adjusting fishing mortality to stock productivity but can be prevented or inhibited by additional anthropogenic impacts such as climate change. Despite management measures to recover fish stocks being in place in legislations such as the European Union´s Common Fisheries Policy (CFP), recovery can be hindered by the occurrence of regime shift dynamics. Such non-linear discontinuous dynamics imply tipping points and bear the characteristics of abrupt change, hysteresis and non-stationary functional relationships. We here used the recent reform of the CFP as a natural experiment to investigate the existence of regime shift dynamics and its potential effects on the recovery potential on six strongly fished or even depleted commercial fish stocks in the North Sea. Using a set of statistical approaches we show that regime shift dynamics exist in all six fish stocks as a response to changes in fishing pressure and temperature. Our results furthermore demonstrate the context-dependence of such dynamics and hence the ability of management measures to rebuild depleted fish stocks, leading to either failed recovery or positive tipping.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Animais , Conservação dos Recursos Naturais/métodos , Pesqueiros , Mudança Climática , Mar do Norte , Dinâmica Populacional , Peixes
2.
Sci Rep ; 11(1): 20609, 2021 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-34663857

RESUMO

Seasonal Influenza A virus (IAV) infections can promote dissemination of upper respiratory tract commensals such as Streptococcus pneumoniae to the lower respiratory tract resulting in severe life-threatening pneumonia. Here, we aimed to compare innate immune responses in the lungs of healthy colonized and non-colonized mice after IAV challenge at the initial asymptomatic stage of infection. Responses during a severe bacterial pneumonia were profiled for comparison. Cytokine and innate immune cell imprints of the lungs were analyzed. Irrespective of the colonization status, mild H1N1 IAV infection was characterized by a bi-phasic disease progression resulting in full recovery of the animals. Already at the asymptomatic stage of viral infection, the pro-inflammatory cytokine response was as high as in pneumococcal pneumonia. Flow cytometry analyses revealed an early influx of inflammatory monocytes into the lungs. Neutrophil influx was mostly limited to bacterial infections. The majority of cells, except monocytes, displayed an activated phenotype characterized by elevated CCR2 and MHCII expression. In conclusion, we show that IAV challenge of colonized healthy mice does not automatically result in severe co-infection. However, a general local inflammatory response was noted at the asymptomatic stage of infection irrespective of the infection type.


Assuntos
Imunidade Inata/imunologia , Infecções por Orthomyxoviridae/imunologia , Infecções Pneumocócicas/imunologia , Animais , Portador Sadio/imunologia , Coinfecção/virologia , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H1N1/patogenicidade , Vírus da Influenza A/imunologia , Vírus da Influenza A/patogenicidade , Pulmão/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/metabolismo , Infecções por Orthomyxoviridae/virologia , Infecções Pneumocócicas/complicações , Pneumonia Bacteriana , Pneumonia Pneumocócica/imunologia , Cultura Primária de Células , Infecções Respiratórias/imunologia , Infecções Respiratórias/virologia , Streptococcus pneumoniae/patogenicidade
3.
Sci Rep ; 11(1): 14259, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34253825

RESUMO

Understanding tipping point dynamics in harvested ecosystems is of crucial importance for sustainable resource management because ignoring their existence imperils social-ecological systems that depend on them. Fisheries collapses provide the best known examples for realizing tipping points with catastrophic ecological, economic and social consequences. However, present-day fisheries management systems still largely ignore the potential of their resources to exhibit such abrupt changes towards irreversible low productive states. Using a combination of statistical changepoint analysis and stochastic cusp modelling, here we show that Western Baltic cod is beyond such a tipping point caused by unsustainable exploitation levels that failed to account for changing environmental conditions. Furthermore, climate change stabilizes a novel and likely irreversible low productivity state of this fish stock that is not adapted to a fast warming environment. We hence argue that ignorance of non-linear resource dynamics has caused the demise of an economically and culturally important social-ecological system which calls for better adaptation of fisheries systems to climate change.

4.
Glob Chang Biol ; 27(7): 1485-1499, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33438266

RESUMO

Global environmental changes have accelerated at an unprecedented rate in recent decades due to human activities. As a consequence, the incidence of novel abiotic conditions and biotic communities, which have been continuously emerging in the Earth system, has rapidly risen. Despite growing attention to the incidence and challenges posed by novelty in terrestrial ecosystems, novelty has not yet been quantified in marine ecosystems. Here, we measured for the rate of novelty (RoN) in abiotic conditions and community structure for three trophic levels, i.e., phytoplankton, zooplankton, and fish, in a large marine system - the Baltic Sea. We measured RoN as the degree of dissimilarity relative to a specific spatial and temporal baseline, and contrasted this with the rate of change as a measure of within-basin change over time. We found that over the past 35 years abiotic and biotic RoN showed complex dynamics varying in time and space, depending on the baseline conditions. RoN in abiotic conditions was smaller in the open Central Baltic Sea than in the Kattegat and the more enclosed Gulf of Bothnia, Gulf of Riga, and Gulf of Finland in the north. We found a similar spatial pattern for biotic assemblages, which resulted from changes in composition and stock size. We identified sea-surface temperature and salinity as key drivers of RoN in biotic communities. Hence, future environmental changes that are expected to affect the biogeochemistry of the Baltic Sea, may favor the rise of biotic novelty. Our results highlighted the need for a deeper understanding of novelty development in marine ecosystems, including interactions between species and trophic levels, ecosystem functioning under novel abiotic conditions, and considering novelty in future management interventions.


Assuntos
Ecossistema , Zooplâncton , Animais , Finlândia , Humanos , Oceanos e Mares , Fitoplâncton
5.
Proc Biol Sci ; 286(1898): 20182877, 2019 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-30862289

RESUMO

Collapses and regime changes are pervasive in complex systems (such as marine ecosystems) governed by multiple stressors. The demise of Atlantic cod ( Gadus morhua) stocks constitutes a text book example of the consequences of overexploiting marine living resources, yet the drivers of these nearly synchronous collapses are still debated. Moreover, it is still unclear why rebuilding of collapsed fish stocks such as cod is often slow or absent. Here, we apply the stochastic cusp model, based on catastrophe theory, and show that collapse and recovery of cod stocks are potentially driven by the specific interaction between exploitation pressure and environmental drivers. Our statistical modelling study demonstrates that for most of the cod stocks, ocean warming could induce a nonlinear discontinuous relationship between fishing pressure and stock size, which would explain hysteresis in their response to reduced exploitation pressure. Our study suggests further that a continuing increase in ocean temperatures will probably limit productivity and hence future fishing opportunities for most cod stocks of the Atlantic Ocean. Moreover, our study contributes to the ongoing discussion on the importance of climate and fishing effects on commercially exploited fish stocks, highlighting the importance of considering discontinuous dynamics in holistic ecosystem-based management approaches, particularly under climate change.


Assuntos
Conservação dos Recursos Naturais , Pesqueiros , Gadus morhua/fisiologia , Aquecimento Global , Temperatura , Animais , Oceano Atlântico , Modelos Biológicos , Dinâmica Populacional , Água do Mar/química , Processos Estocásticos
7.
PLoS One ; 12(11): e0188205, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29136658

RESUMO

Understanding spatio-temporal dynamics of biotic communities containing large numbers of species is crucial to guide ecosystem management and conservation efforts. However, traditional approaches usually focus on studying community dynamics either in space or in time, often failing to fully account for interlinked spatio-temporal changes. In this study, we demonstrate and promote the use of tensor decomposition for disentangling spatio-temporal community dynamics in long-term monitoring data. Tensor decomposition builds on traditional multivariate statistics (e.g. Principal Component Analysis) but extends it to multiple dimensions. This extension allows for the synchronized study of multiple ecological variables measured repeatedly in time and space. We applied this comprehensive approach to explore the spatio-temporal dynamics of 65 demersal fish species in the North Sea, a marine ecosystem strongly altered by human activities and climate change. Our case study demonstrates how tensor decomposition can successfully (i) characterize the main spatio-temporal patterns and trends in species abundances, (ii) identify sub-communities of species that share similar spatial distribution and temporal dynamics, and (iii) reveal external drivers of change. Our results revealed a strong spatial structure in fish assemblages persistent over time and linked to differences in depth, primary production and seasonality. Furthermore, we simultaneously characterized important temporal distribution changes related to the low frequency temperature variability inherent in the Atlantic Multidecadal Oscillation. Finally, we identified six major sub-communities composed of species sharing similar spatial distribution patterns and temporal dynamics. Our case study demonstrates the application and benefits of using tensor decomposition for studying complex community data sets usually derived from large-scale monitoring programs.


Assuntos
Ecossistema , Animais , Biodiversidade , Mudança Climática , Peixes , Humanos , Biologia Marinha
8.
Mol Cancer Ther ; 15(2): 287-98, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26590165

RESUMO

Multiple myeloma is a plasma cell malignancy characterized by marked heterogeneous genomic instability including frequent genetic alterations in epigenetic enzymes. In particular, the histone methyltransferase Enhancer of Zeste Homolog 2 (EZH2) is overexpressed in multiple myeloma. EZH2 is the catalytic component of the polycomb repressive complex 2 (PRC2), a master transcriptional regulator of differentiation. EZH2 catalyzes methylation of lysine 27 on histone H3 and its deregulation in cancer has been reported to contribute to silencing of tumor suppressor genes, resulting in a more undifferentiated state, and thereby contributing to the multiple myeloma phenotype. In this study, we propose the use of EZH2 inhibitors as a new therapeutic approach for the treatment of multiple myeloma. We demonstrate that EZH2 inhibition causes a global reduction of H3K27me3 in multiple myeloma cells, promoting reexpression of EZH2-repressed tumor suppressor genes in a subset of cell lines. As a result of this transcriptional activation, multiple myeloma cells treated with EZH2 inhibitors become more adherent and less proliferative compared with untreated cells. The antitumor efficacy of EZH2 inhibitors is also confirmed in vivo in a multiple myeloma xenograft model in mice. Together, our data suggest that EZH2 inhibition may provide a new therapy for multiple myeloma treatment and a promising addition to current treatment options. Mol Cancer Ther; 15(2); 287-98. ©2015 AACR.


Assuntos
Inibidores Enzimáticos/administração & dosagem , Histonas/metabolismo , Mieloma Múltiplo/tratamento farmacológico , Complexo Repressor Polycomb 2/metabolismo , Proteínas Supressoras de Tumor/genética , Animais , Linhagem Celular Tumoral , Proteína Potenciadora do Homólogo 2 de Zeste , Inibidores Enzimáticos/farmacologia , Epigênese Genética/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Mieloma Múltiplo/enzimologia , Mieloma Múltiplo/genética , Complexo Repressor Polycomb 2/antagonistas & inibidores , Microambiente Tumoral/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
9.
Exp Cell Res ; 339(1): 35-43, 2015 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-26475730

RESUMO

Invasion processes underlie or accompany several pathological processes but only a limited number of high-throughput capable phenotypic models exist to test anti-invasive compounds in vitro. We here evaluated 3D co-cultures as a high-content phenotypic screening system for fibrotic invasive processes. 3D multicellular spheroids were used as living tissue surrogates in co-culture with fluorescently labeled lung fibroblasts to monitor invasion processes by automated microscopy. This setup was used to screen a compound library containing 480 known bioactive substances. Identified hits prevented fibroblast invasion and could be subdivided into two hit classes. First, Prostaglandins were shown to prevent fibroblast invasion, most likely mediated by the prostaglandin EP2 receptor and generation of cAMP. Additionally, Rho-associated protein kinase (ROCK) inhibitors prevented fibroblast invasion, possibly by inactivation of myosin II. Importantly, both Prostaglandins and ROCK inhibitors are potential treatment options shown to be effective in in vitro and in vivo models of fibrotic diseases. This validates the presented novel phenotypic screening approach for the evaluation of potential inhibitors and the identification of novel compounds with activity in diseases that are associated with fibroblast invasion.


Assuntos
Neoplasias da Mama/patologia , Técnicas de Cultura de Células , Fibroblastos/patologia , Ensaios de Triagem em Larga Escala , Prostaglandinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Esferoides Celulares/patologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Processamento de Imagem Assistida por Computador , Técnicas Imunoenzimáticas , Esferoides Celulares/efeitos dos fármacos , Esferoides Celulares/metabolismo , Células Tumorais Cultivadas , Quinases Associadas a rho/antagonistas & inibidores , Quinases Associadas a rho/metabolismo
10.
PLoS One ; 9(3): e90875, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24614110

RESUMO

Understanding and predicting species distribution in space and time and consequently community structure and dynamics is an important issue in ecology, and particularly in climate change research. A crucial factor determining the composition and dynamics of animal populations is habitat heterogeneity, i.e., the number of structural elements in a given locality. In the marine pelagic environment habitat heterogeneity is represented by the distribution of physical oceanographic parameters such as temperature, salinity and oxygen that are closely linked to atmospheric conditions. Little attention has been given, however, to the role of habitat heterogeneity in modulating the response of animal communities to external climate forcing. Here we investigate the long-term dynamics of Acartia spp., Temora longicornis, and Pseudocalanus acuspes, three dominant zooplankton species inhabiting different pelagic habitats in the Central Baltic Sea (CBS). We use the three copepods as indicator species for changes in the CBS zooplankton community and apply non-linear statistical modeling techniques to compare spatial population trends and to identify their drivers. We demonstrate that effects of climate variability and change depend strongly on species-specific habitat utilization, being more direct and pronounced at the upper water layer. We propose that the differential functional response to climate-related drivers in relation to strong habitat segregation is due to alterations of the species' environmental niches. We stress the importance of understanding how anticipated climate change will affect ecological niches and habitats in order to project spatio-temporal changes in species abundance and distribution.


Assuntos
Mudança Climática , Ecossistema , Zooplâncton/crescimento & desenvolvimento , Animais , Países Bálticos , Geografia , Modelos Estatísticos , Estações do Ano , Especificidade da Espécie , Fatores de Tempo
11.
Lab Chip ; 14(5): 998-1004, 2014 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-24441950

RESUMO

A silicon based chip device with a regular array of more than 100,000 cylindrical sub-microelectrodes has been developed for the dielectrophoretic (DEP) manipulation of nanoparticles and molecules in solution. It was fabricated by a standard CMOS (complementary metal oxide semiconductor) compatible process. The distribution of the electrical field gradient was calculated to predict the applicability of the setup. Heating due to field application was determined microscopically using a temperature sensitive fluorescent dye. Depending on voltage and frequency, temperature increase was found to be compatible with protein function. Successful field controlled immobilisation of biomolecules from solution was demonstrated with the autofluorescent protein R-phycoerythrin (RPE) and with fluorescently labelled IgG antibodies. Biological activity after DEP application was proven by immobilisation of an anti-RPE antibody and subsequent binding of RPE. These results demonstrate that the developed chip system allows the directed immobilisation of proteins onto microelectrodes by dielectrophoresis without the need for any chemical modification and that protein function is preserved. Being based on standard lithographical methods, further miniaturisation and on-chip integration of electronics towards a multiparameter single cell analysis system appear near at hand.


Assuntos
Anticorpos/imunologia , Eletroforese , Análise em Microsséries/métodos , Animais , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Corantes Fluorescentes/química , Cabras , Humanos , Análise em Microsséries/instrumentação , Microeletrodos , Miniaturização , Nanopartículas/química , Ficoeritrina/imunologia , Ficoeritrina/metabolismo , Semicondutores , Temperatura
12.
PLoS One ; 8(10): e75439, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24116045

RESUMO

Several marine ecosystems under anthropogenic pressure have experienced shifts from one ecological state to another. In the central Baltic Sea, the regime shift of the 1980s has been associated with food-web reorganization and redirection of energy flow pathways. These long-term dynamics from 1974 to 2006 have been simulated here using a food-web model forced by climate and fishing. Ecological network analysis was performed to calculate indices of ecosystem change. The model replicated the regime shift. The analyses of indicators suggested that the system's resilience was higher prior to 1988 and lower thereafter. The ecosystem topology also changed from a web-like structure to a linearized food-web.


Assuntos
Ecossistema , Modelos Teóricos , Oceanos e Mares , Animais , Biomassa , Cadeia Alimentar
13.
PLoS One ; 7(7): e38410, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22808007

RESUMO

Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Using real monitoring data of a key ecosystem component, we here apply multiple early-warning indicators in order to assess their ability to forewarn a major ecosystem regime shift in the Central Baltic Sea. We show that some indicators and methods can result in clear early-warning signals, while other methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face of ecosystem change.


Assuntos
Ecossistema , Modelos Biológicos , Zooplâncton/fisiologia , Animais , Mudança Climática , Humanos , Oceanos e Mares , Temperatura , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...