RESUMO
How pancreatic ß-cells acquire function in vivo is a long-standing mystery due to the lack of technology to visualize ß-cell function in living animals. Here, we applied a high-resolution two-photon light-sheet microscope for the first in vivo imaging of Ca2+activity of every ß-cell in Tg (ins:Rcamp1.07) zebrafish. We reveal that the heterogeneity of ß-cell functional development in vivo occurred as two waves propagating from the islet mantle to the core, coordinated by islet vascularization. Increasing amounts of glucose induced functional acquisition and enhancement of ß-cells via activating calcineurin/nuclear factor of activated T-cells (NFAT) signaling. Conserved in mammalians, calcineurin/NFAT prompted high-glucose-stimulated insulin secretion of neonatal mouse islets cultured in vitro. However, the reduction in low-glucose-stimulated insulin secretion was dependent on optimal glucose but independent of calcineurin/NFAT. Thus, combination of optimal glucose and calcineurin activation represents a previously unexplored strategy for promoting functional maturation of stem cell-derived ß-like cells in vitro.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Glucose/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Imagem Molecular/métodos , Pâncreas/efeitos dos fármacos , Análise de Célula Única/métodos , Animais , Animais Recém-Nascidos , Calcineurina/genética , Calcineurina/metabolismo , Diferenciação Celular/efeitos dos fármacos , Embrião não Mamífero , Glucose/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Camundongos , Fatores de Transcrição NFATC/genética , Fatores de Transcrição NFATC/metabolismo , Pâncreas/irrigação sanguínea , Pâncreas/citologia , Pâncreas/crescimento & desenvolvimento , Transdução de Sinais , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Peixe-ZebraRESUMO
We report a mode-locked fiber laser working at a 1 GHz fundamental repetition rate. The laser delivers a 600 mW average power at a pump power of 1800 mW. The pulse spectrum bandwidth was 23 nm to support 64 fs near-transform-limited pulses. An octave-spanning supercontinuum from 590 to 1350 nm was generated in a tapered photonic crystal fiber solely with the mode-locked fiber-laser output, without amplifiers. A 30 dB f(ceo) beat signal was detected via f-to-2f interferometer.
RESUMO
A tapered silica photonic crystal fiber was designed and fabricated to generate more than one octave spanning supercontinuum (from 550 nm to 1400 nm at -30 dB level), by an input pulse of 40 fs 200 pJ directly from an Yb:fiber ring laser. The low pulse energy spectrum broadening are favorable to generate the high contrast f ceo signals with low noise. The f ceo signal with 40 dB signal-to-noise ratio was detected, which helps to build a compact real-world frequency comb.
