341 research outputs found
Caracterização in silico de genes de expansina presentes em cafeeiro (Coffea arabica L.).
As expansinas (EXPs) são proteínas que promovem o relaxamento e extensão da parede celular em plantas, sendo codificadas por uma multifamília gênica e classificadas em: ?-expansinas, ?-expansinas, expansin-like A (EXLA) e expansin-like B (EXLB). Estas proteínas atuam no alongamento celular, maciez dos frutos, abscisão, germinação e polinização. As ?-expansinas representam a maior família e relacionam-se diretamente com o controle da extensão da parede celular em processos de desenvolvimento. Visto que a maturação uniforme dos frutos de café contribui para a qualidade da bebida, este trabalho teve por objetivo identificar e caracterizar in silico genes de expansinas envolvidas neste processo. Através da mineração dos dados do Genoma Café foram encontrados 28 contigs referentes às EXPs, sendo dois contigs de EXLB, um de EXLA e os demais pertencentes à família das ?-expansinas. Dentro desta ultima família foram identificados quatro contigs relacionados com o desenvolvimento dos frutos do cafeeiro. Comparação dos contigs obtidos nos bancos do Projeto Genoma Café e de contigs no banco de dados HarvEST Coffea permitiu a caracterização in silico da expressão dos contigs nos diferentes estádios de maturação dos frutos
Measurements of the Acidification Kinetics of Single SynaptopHluorin Vesicles
AbstractUptake of neurotransmitters into synaptic vesicles is driven by the proton gradient established across the vesicle membrane. The acidification of synaptic vesicles, therefore, is a crucial component of vesicle function. Here we present measurements of acidification rate constants from isolated, single synaptic vesicles. Vesicles were purified from mice expressing a fusion protein termed SynaptopHluorin created by the fusion of VAMP/synaptobrevin to the pH-sensitive super-ecliptic green fluorescent protein. We calibrated SynaptopHluorin fluorescence to determine the relationship between fluorescence intensity and internal vesicle pH, and used these values to measure the rate constant of vesicle acidification. We also measured the effects of ATP, glutamate, and chloride on acidification. We report acidification time constants of 500 ms to 1 s. The rate of acidification increased with increasing extravesicular concentrations of ATP and glutamate. These data provide an upper and a lower bound for vesicle acidification and indicate that vesicle readiness can be regulated by changes in energy and transmitter availability
Análise in silico de pectinametilesterases de Coffea spp.
A maturação desuniforme dos frutos do cafeeiro, associada a práticas inadequadas de colheita e pós-colheita, pode prejudicar a qualidade final do café. Visando compreender melhor os genes envolvidos na maturação de frutos do cafeeiro foram iniciados estudos in silico e in vivo da atividade da pectinametilesterase (PME-EC 3.2.1.11). A PME é a enzima responsável por catalisar a desmetilação de ésteres metílicos dos ácidos poligalacturônicos e se encontra distribuída em raízes, caules, folhas e frutos da grande maioria das plantas superiores. Essa enzima tem um importante papel no amaciamento de frutos pelo aumento da susceptibilidade das pectinas a poligalacturonase (PG) durante o amadurecimento. A análise in silico foi realizada através de buscas no banco de dados disponibilizados pelo projeto Genoma Café, assim como de outros bancos de domínio público. Foram identificados inicialmente 31 contigs, mas apenas oito destes apresentavam seqüências provenientes de bibliotecas de frutos de café. Comparação dos contigs obtidos nos bancos de dados do Genoma Café e do HarvEST Coffea, permitiu a caracterização in silico da expressão de alguns dos contigs nos diferentes estágios de maturação dos frutos. Análise da expressão in vivo destes contigs está sendo realizada para validação dos dados obtidos in silico
Discriminating chaotic and stochastic time series using permutation entropy and artificial neural networks
Extracting relevant properties of empirical signals generated by nonlinear,
stochastic, and high-dimensional systems is a challenge of complex systems
research. Open questions are how to differentiate chaotic signals from
stochastic ones, and how to quantify nonlinear and/or high-order temporal
correlations. Here we propose a new technique to reliably address both
problems. Our approach follows two steps: first, we train an artificial neural
network (ANN) with flicker (colored) noise to predict the value of the
parameter, , that determines the strength of the correlation of the
noise. To predict the ANN input features are a set of probabilities
that are extracted from the time series by using symbolic ordinal analysis.
Then, we input to the trained ANN the probabilities extracted from the time
series of interest, and analyze the ANN output. We find that the value
returned by the ANN is informative of the temporal correlations present in the
time series. To distinguish between stochastic and chaotic signals, we exploit
the fact that the difference between the permutation entropy (PE) of a given
time series and the PE of flicker noise with the same parameter is
small when the time series is stochastic, but it is large when the time series
is chaotic. We validate our technique by analysing synthetic and empirical time
series whose nature is well established. We also demonstrate the robustness of
our approach with respect to the length of the time series and to the level of
noise. We expect that our algorithm, which is freely available, will be very
useful to the community
Small changes at single nodes can shift global network dynamics
Understanding the sensitivity of a system's behavior with respect to
parameter changes is essential for many applications. This sensitivity may be
desired - for instance in the brain, where a large repertoire of different
dynamics, particularly different synchronization patterns, is crucial - or may
be undesired - for instance in power grids, where disruptions to
synchronization may lead to blackouts. In this work, we show that the dynamics
of networks of phase oscillators can acquire a very large and complex
sensitivity to changes made in either their units' parameters or in their
connections - even modifications made to a parameter of a single unit can
radically alter the global dynamics of the network in an unpredictable manner.
As a consequence, each modification leads to a different path to phase
synchronization manifested as large fluctuations along that path. This
dynamical malleability occurs over a wide parameter region, around the
network's two transitions to phase synchronization. One transition is induced
by increasing the coupling strength between the units, and another is induced
by increasing the prevalence of long-range connections. Specifically, we study
Kuramoto phase oscillators connected under either Watts-Strogatz or
distance-dependent topologies to analyze the statistical properties of the
fluctuations along the paths to phase synchrony. We argue that this increase in
the dynamical malleability is a general phenomenon, as suggested by both
previous studies and the theory of phase transitions.Comment: 14 pages, 8 figure
Spatial permutation entropy distinguishes resting brain states
We use ordinal analysis and spatial permutation entropy to distinguish between eyes-open and eyes-closed resting brain states. To do so, we analyze EEG data recorded with 64 electrodes from 109 healthy subjects, under two one-minute baseline runs: One with eyes open, and one with eyes closed. We use spatial ordinal analysis to distinguish between these states, where the permutation entropy is evaluated considering the spatial distribution of electrodes for each time instant. We analyze both raw and post-processed data considering only the alpha-band frequency (8–12 Hz) which is known to be important for resting states in the brain. We conclude that spatial ordinal analysis captures information about correlations between time series in different electrodes. This allows the discrimination of eyes closed and eyes open resting states in both raw and filtered data. Filtering the data only amplifies the distinction between states. Importantly, our approach does not require EEG signal pre-processing, which is an advantage for real-time applications, such as brain-computer interfaces.B.R.R.B. and E.E.N.M. acknowledge support of São Paulo Research Foundation (FAPESP), Brazil, Proc. 2018/03211-6 and 2021/09839-0; and Financiadora de Estudos e Projetos (FINEP), Brazil. R.C.B. acknowledges support of Western Institute for Neuroscience Clinical Research Postdoctoral Fellowship and Western Academy for Advanced Research. K.L.R. acknowledges supported of German Academic Exchange Service (DAAD). C.M. acknowledges support of Ministerio de Ciencia, Innovación ������ Universidades (PID2021-123994NB-C21), Spain and Institució Catalana de Recerca i Estudis Avançats (ICREA), Spain.Peer ReviewedPostprint (published version
Análise de genes expressos durante estádios finais da maturação de frutos de café.
A maturação uniforme dos frutos do cafeeiro relaciona-se diretamente com a qualidade da bebida. Diferentes floradas em um mesmo cafeeiro propiciam frutos em estádios desiguais de maturação podendo resultar em uma maior dificuldade na colheita, maior gasto com mão de obra e queda na qualidade do produto. Em frutos climatéricos, o processo final da maturação é desencadeado por um grande acúmulo de etileno, seguido por mudança bioquímicas e fisiológicas que promovem principalmente a desestabilização da parede celular dos frutos, composta principalmente por compostos pécticos. As pectinas são degradadas devido à solubilização e despolimerização da parede celular vegetal em decorrência da ação de enzimas como: pectinametilesterase, poligalacturonase, xiloglucanases, xilanases, pectinaliases e bgalactosidases. Nosso objetivo principal é caracterizar e entender as mudanças na expressão gênica e enzimática que ocorrem durante a maturação dos frutos de café, visando melhorar a uniformidade da maturação. Neste trabalho foram feitos estudos de expressão de genes que codificam para ACC oxidase, expansina, pectinametilesterase e poligalacturonases, através da análise ?in silico? do banco de dados do Projeto Genoma Café, e experimentos de expressão dos genes e enzimas. Análise de transcritos demonstrou um aumento de ACC oxidase em frutos verdecana seguido da atividade de pectinametilesterases em estágios intermediários de maturação (frutos avermelhados). A atividade da PG foi detectada nos estádios finais de maturação, principalmente em frutos cereja
The Institutional Framework for Doing Sports Business: Principles of EU Competition Policy in Sports Markets
Wettbewerb und Regulierung
Wettbewerb und Regulierung werfen sowohl aus einer wirtschafts- als auch aus einer politikwissenschaftlichen Perspektive interessante Fragestellungen auf und haben daher in beiden Disziplinen umfangreiche Beachtung gefunden. Der vorliegende Beitrag gibt eine Übersicht über beide Herangehensweisen. Dabei wer-den zunächst die grundlegenden Unterschiede und Gemeinsamkeiten offengelegt (Abschnitt 2), bevor die disziplinären Schwerpunkte in der Analyse vorgestellt, und aus Sicht der jeweils anderen Disziplin kommentiert werden (Abschnitte 3 und 4). Wir kommen zu dem Ergebnis, dass beide Sichtweisen in erster Linie komplementär sind und sich gegenseitig befruchten können
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