Dual-objective two-photon microscope for volumetric imaging of dense scattering biological samples by bidirectional excitation and collection

Full view observation throughout entire specimens over a prolonged period is crucial when exploring the physiological functions and system-level behaviors.Multi-photon microscopy(MPM)has been widely employed for such purposes owing to its deep penetration ability.However,the current MPM struggles with balancing the imaging depth and quality while avoiding photodamage for the exponential increasement of excitation power with the imaging depth.Here,we present a dual-objective two-photon microscope(Duo-2P),characterized by bidirectional two-photon excitation and fluorescence collection,for long-duration volumetric imaging of dense scattering samples.Duo-2P effectively doubles the imaging depth,reduces the total excitation energy by an order of magnitude for samples with a thickness five times the scattering length,and enhances the signal-to-noise ratio up to 1.4 times.Leveraging these advantages,we acquired volumetric images of a 380-μm suprachiasmatic nucleus slice for continuous 4-h recording at a rate of 1.67 s/volume,visualized the calcium activities over 4000 neurons,and uncovered their state-switching behavior.We conclude that Duo-2P provides an elegant and powerful means to overcome the fundamental depth limit while mitigating photodamages for deep tissue volumetric imaging.

Effective therapy of the small-molecule cocktail 5SM on adult rat heart after ischemia–reperfusion injury

Dear Editor,Myocardial infarction(MI)is one of the leading causes of cardiovascular-related mortality worldwide.Timely restoration of the blood supply to ischemic my-ocardium by thrombolysis or percuta-neous coronary intervention is a com-mon clinical practice and decreases the mortality risk for MI patients(Heusch,2020).

Miniature Fluorescence Microscopy for Imaging Brain Activity in Freely-Behaving Animals

An ultimate goal of neuroscience is to decipher the principles underlying neuronal information processing at the molecular,cellular,circuit,and system levels.The advent of miniature fluorescence microscopy has furthered the quest by visualizing brain activities and structural dynamics in animals engaged in self-determined behaviors.In this brief review,we summarize recent advances in miniature fluorescence microscopy for neuroscience,focusing mostly on two mainstream solutions-miniature single-photon microscopy,and miniature two-photon microscopy.We discuss their technical advantages and limitations as well as unmet challenges for future improvement.Examples of preliminary applications are also presented to reflect on a new trend of brain imaging in experimental paradigms involving body movements,long and complex protocols,and even disease progression and aging.

Visualizing Seizure Propagation in Freely-moving Mice via Miniature Two-photon Microscopy

DearEditor,Due to the tight and precise associations between behaviors and neural activities,the investigation of neuronal activity in freely-movingand behavinganimals isamajor unaccomplished goal in neuroscience.Epileptiform seizures,characterized by hyper-synchronized discharges and hyper-excitation in neuronal networks,are one of the most common neurological disorders.

Chemical screening links disulfiram with cardiac protection after ischemic injury

Ischemia-reperfusion injury occurs after reperfusion treatment for patients suffering myocardial infarction,however the underlying mechanisms are incompletely understood and effective pharmacological interventions are limited.Here,we report the identification and characterization of the FDA-approved drug disulfiram(DSF)as a cardioprotective compound.By applying high-throughput chemical screening,we found that DSF decreased H_(2)O_(2)-induced cardiomyocyte death by inhibiting Gasdermin D,but not ALDH1,in cardiomyocytes.Oral gavage of DSF decreased myocardial infarct size and improved heart function after myocardial ischemia-reperfusion injury in rats.Therefore,this work reveals DSF as a potential therapeutic compound for the treatment of ischemic heart disease.