Suppression of Contraction Raises Calcium Ion Levels in the Heart of Zebrafish Larvae.

Zebrafish larvae have emerged as a valuable model for studying heart physiology and pathophysiology, as well as for drug discovery, in part thanks to its transparency, which simplifies microscopy. However, in fluorescence-based optical mapping, the beating of the heart results in motion artifacts. Two approaches have been employed to eliminate heart motion during calcium or voltage mapping in zebrafish larvae: the knockdown of cardiac troponin T2A and the use of myosin inhibitors.

ERG potassium channels and T-type calcium channels contribute to the pacemaker and atrioventricular conduction in zebrafish larvae.

Aim: Bradyarrhythmias result from inhibition of automaticity, prolonged repolarization, or slow conduction in the heart. The ERG channels mediate the repolarizing current I in the cardiac action potential, whereas T-type calcium channels (TTCC) are involved in the sinoatrial pacemaker and atrioventricular conduction in mammals. Zebrafish have become a valuable research model for human cardiac electrophysiology and disease.

Early calcium and cardiac contraction defects in a model of phospholamban R9C mutation in zebrafish.

The phospholamban mutation Arg 9 to Cys (R9C) has been found to cause a dilated cardiomyopathy in humans and in transgenic mice, with ventricular dilation and premature death. Emerging evidence suggests that phospholamban R9C is a loss-of-function mutation with dominant negative effect on SERCA2a activity. We imaged calcium and cardiac contraction simultaneously in 3 and 9 days-post-fertilization (dpf) zebrafish larvae expressing plnb in the heart to unveil the early pathological pathway that triggers the disease.

Optimized Aequorin Reconstitution Protocol to Visualize Calcium Ion Transients in the Heart of Transgenic Zebrafish Embryos In Vivo.

We introduce how to image calcium ion levels in the heart of zebrafish embryos and larvae up to 5 days post-fertilization with the photoprotein green fluorescent protein (GFP)-aequorin (GA) in the transgenic line Tg(myl7:GA). Incubation of the embryos with CTZ to obtain the functional photoprotein yields few emission counts, suggesting that, when the heart is beating, the rate of aequorin consumption is faster than that of the reconstitution with CTZ. In this chapter, we present an improved aequorin reconstitution protocol.

Simultaneous imaging of calcium and contraction in the beating heart of zebrafish larvae.

models of cardiac function maintain the complex relationship of cardiomyocytes with other heart cells, as well as the paracrine and mechanoelectrical feedback mechanisms. We aimed at imaging calcium transients simultaneously with heart contraction in zebrafish larvae. To image calcium in beating hearts, we generated a zebrafish transgenic line expressing the FRET-based ratiometric biosensor Twitch-4.

Cardioluminescence in Transgenic Zebrafish Larvae: A Calcium Imaging Tool to Study Drug Effects and Pathological Modeling.

Zebrafish embryos and larvae have emerged as an excellent model in cardiovascular research and are amenable to live imaging with genetically encoded biosensors to study cardiac cell behaviours, including calcium dynamics. To monitor calcium ion levels in three to five days post-fertilization larvae, we have used bioluminescence. We generated a transgenic line expressing GFP-aequorin in the heart, , and optimized a reconstitution protocol to boost aequorin luminescence.

Mapping Calcium Dynamics in the Heart of Zebrafish Embryos with Ratiometric Genetically Encoded Calcium Indicators.

Zebrafish embryos have been proposed as a cost-effective vertebrate model to study heart function. Many fluorescent genetically encoded Ca indicators (GECIs) have been developed, but those with ratiometric readout seem more appropriate to image a moving organ such as the heart. Four ratiometric GECIs based on troponin C, TN-XXL, Twitch-1, Twitch-2B, and Twitch-4 were expressed transiently in the heart of zebrafish embryos.

Visualization of Mitochondrial Ca Signals in Skeletal Muscle of Zebrafish Embryos with Bioluminescent Indicators.

Mitochondria are believed to play an important role in shaping the intracellular Ca transients during skeletal muscle contraction. There is discussion about whether mitochondrial matrix Ca dynamics always mirror the cytoplasmic changes and whether this happens in vivo in whole organisms. In this study, we characterized cytosolic and mitochondrial Ca signals during spontaneous skeletal muscle contractions in zebrafish embryos expressing bioluminescent GFP-aequorin (GA, cytoplasm) and mitoGFP-aequorin (mitoGA, trapped in the mitochondrial matrix).

Geographical distribution of Leishmania species in Colombia, 1985-2017.

Introduction: Knowledge of the geographical distribution of Leishmania species allows guiding the sampling to little-studied areas and implementing strategies to define risk zones and priority areas for control.

Objective: Given that there is no publication that collects this information, the search, review, and compilation of the available scientific literature that has identified species in Colombia is presented in this paper.

Materials And Methods: A bibliographic search was performed in PubMed, Web of Knowledge, Google Scholar, SciELO and LILACS with the terms "(Leishmania OR Leishmaniasis) AND species AND Colombia", without restrictions on publication year, language or infected organism; records of national scientific events and repositories of theses from Colombian universities were also included.

Evaluating the spatial distribution of Leishmania parasites in Colombia from clinical samples and human isolates (1999 to 2016).

In Colombia, nine species of parasites of the genus Leishmania circulate in more than 20 sand fly species, putting at risk of contracting the disease approximately 60% of the population. The Federico Lleras Acosta Dermatological Center, a reference center in Colombia, has been treating patients with cutaneous and mucosal leishmaniasis for more than 15 years, identifying the infecting Leishmania species from different clinical samples, and recording systematically all the epidemiological and geographic information related to each diagnosed patient. With this valuable information, the objective of this work was to perform a long term and large-scale study, aiming to identify the Leishmania species circulating in Colombia from clinical samples from 1999 to 2016, and to assess their current and potential spatial distribution.