Eric Karplus

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Through the injection of f-aequorin (a calcium-specific luminescent reporter) and the use of an imaging photon detector, we see a distinct localized elevation of intracellular calcium that accompanies the appearance of the first furrow arc at the blastodisc surface: the furrow positioning signal. As the leading edges of the arc progress outward toward the(More)
In this paper, we report on the investigation of silicon avalanche photodiodes (APDs) for high-energy photon imaging applications. This includes a new APD design that provides X-ray and -ray imaging with significant reduction in electronic readout requirements. This new APD design, referred to as position-sensitive avalanche photodiode (PSAPD), involves(More)
Oscillations of cytosolic free calcium levels have been shown to influence gene regulation and cell differentiation in a variety of model systems. Intercellular calcium waves thus present a plausible mechanism for coordinating cellular processes during embryogenesis. Herein we report use of aequorin and a photon imaging microscope to directly observe a(More)
The aim of this work was to characterize the ion current that enters mouse metatarsal bones following damage to the cortex. We assessed both the spatial distribution of this current and its dependence on the presence of bicarbonate in the medium. We used a voltage-sensitive probe system vibrating in two dimensions and recorded the signal as function of the(More)
Accumulating evidence from several systems suggests that nuclear envelope breakdown (NEB) is triggered by an endogenous transient of free calcium. Using h- and f-semisynthetic aequorins as cytosolic calcium indicators, we have clearly and regularly visualized a single large, global calcium transient just before first NEB in normally developing, monospermic(More)
The construction and application of genetically encoded intracellular calcium concentration ([Ca2+]i) indicators has a checkered history. Excitement raised over the creation of new probes is often followed by disappointment when it is found that the initial demonstrations of [Ca2+]i sensing capability cannot be leveraged into real scientific advances.(More)
In this chapter, we describe the practical aspects of measuring [Ca(2+)] transients that are generated in a particular cytoplasmic domain, or within a specific organelle or its periorganellar environment, using bioluminescent, genetically encoded and targeted Ca(2+) reporters, especially those based on apoaequorin. We also list examples of the organisms,(More)
In this review, we take a retrospective look at the discovery and utilization of the Ca(2+) -sensitive bioluminescent protein complex, aequorin. We do consider the contribution it has made to our understanding of the natural phenomenon of bioluminescence, but it is in the application of extracted and purified aequorin as a reporter of Ca(2+) dynamics in(More)