Michelle Yue

We present dynamic spectrally encoded confocal microscopy (D-SECM), a high-speed, label-free imaging modality for real-time visualization of subcellular metabolic activity. Sequential, optically sectioned SECM images, with a lateral resolution of 0.62 µm–0.88 µm, were acquired at 100 fps by a modified swept source SECM system, stabilized by fiber-Bragg grating swept source synchronization. D-SECM images are created through real-time pixelwise power spectra mapping into frequency-dependent RGB channels, enabled by GPU-accelerated parallel processing. Validation on freshly excised mouse liver tissue demonstrates that metabolic contrast is detectable with exposure durations as short as 40 ms in the liver. Moreover, volume-prioritized scanning enables three-dimensional D-SECM images to be acquired within a second. In addition to the liver, D-SECM has also been demonstrated in multiple organs, including the lung, thyroid, kidney, and pancreas. These capabilities position D-SECM as a powerful and scalable platform for high-speed, label-free imaging of metabolic dynamics, with unique potential for both basic research and real-time clinical applications.

The intracellular and intercellular flux of calcium ions represents an ancient and universal mode of signaling that regulates an extensive array of cellular processes. Evidence for the central role of calcium signaling includes various techniques that allow the visualization of calcium activity in living cells. While extensively investigated in mature cells, calcium activity is equally important in developing cells, particularly the embryonic nervous system where it has been implicated in a wide variety array of determinative events. However, unlike in mature cells, where the calcium dynamics display regular, predictable patterns, calcium activity in developing systems is far more sporadic, irregular, and diverse. This renders the ability to assess calcium activity in a consistent manner extremely challenging, challenges reflected in the diversity of methods employed to analyze calcium activity in neural development. Here we review the wide array of calcium detection and analysis methods used across studies, limiting the extent to which they can be comparatively analyzed. The goal is to provide investigators not only with an overview of calcium activity analysis techniques currently available, but also to offer suggestions for future work and standardization to enable informative comparative evaluations of this fundamental and important process in neural development.

Information for organismal patterning can come from a variety of sources. We investigate the possibility that instructive influences for normal embryonic development are provided not only at the level of cells within the embryo, but also via interactions between embryos. To explore this, we challenge groups of embryos with disruptors of normal development while varying group size. Here, we show that Xenopus laevis embryos are much more sensitive to a diverse set of chemical and molecular-biological perturbations when allowed to develop alone or in small groups, than in large groups. Keeping per-embryo exposure constant, we find that increasing the number of exposed embryos in a cohort increases the rate of survival while incidence of defects decreases. This inter-embryo assistance effect is mediated by short-range diffusible signals and involves the P2 ATP receptor. Our data and computational model emphasize that morphogenesis is a collective phenomenon not only at the level of cells, but also of whole bodies, and that cohort size is a crucial variable in studies of ecotoxicology, teratogenesis, and developmental plasticity.