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. However, these methods disrupt the mechano-electric and mechano-mechanic coupling mechanisms. We have used ratiometric genetically encoded biosensors to image calcium in the beating heart of intact zebrafish larvae because ratiometric quantification corrects for motion artifacts. In this study, we found that halting heart motion by genetic means (injection of tnnt2a morpholino) or chemical tools (incubation with para-aminoblebbistatin) leads to bradycardia, and increases calcium levels and the size of the calcium transients, likely by abolishing a feedback mechanism that connects contraction with calcium regulation. These outcomes were not influenced by the calcium-binding domain of the gene-encoded biosensors employed, as biosensors with a modified troponin C (Twitch-4), calmodulin (mCyRFP1-GCaMP6f), or the photoprotein aequorin (GFP-aequorin) all yielded similar results. Cardiac contraction appears to be an important regulator of systolic and diastolic Ca2+ levels, and of the heart rate.

RND3 Potentiates Proinflammatory Activation through NOTCH Signaling in Activated Macrophages.

Macrophage activation is a complex process with multiple control elements that ensures an adequate response to the aggressor pathogens and, on the other hand, avoids an excess of inflammatory activity that could cause tissue damage. In this study, we have identified RND3, a small GTP-binding protein, as a new element in the complex signaling process that leads to macrophage activation. We show that RND3 expression is transiently induced in macrophages activated through Toll receptors and potentiated by IFN-γ. We also demonstrate that RND3 increases NOTCH signaling in macrophages by favoring NOTCH1 expression and its nuclear activity; however, Rnd3 expression seems to be inhibited by NOTCH signaling, setting up a negative regulatory feedback loop. Moreover, increased RND3 protein levels seem to potentiate NFκB and STAT1 transcriptional activity resulting in increased expression of proinflammatory genes, such as Tnf-α, Irf-1, or Cxcl-10. Altogether, our results indicate that RND3 seems to be a new regulatory element which could control the activation of macrophages, able to fine tune the inflammatory response through NOTCH.

Effect of Crocus sativus L. Stigmas Microwave Dehydration on Picrocrocin, Safranal and Crocetin Esters.

The dehydration process is the basis to obtain high quality saffron and to preserve it for a long time. This process modifies saffron's main metabolites that define its quality, and are responsible for the characteristic color, taste, and aroma of the spice. In this work, the effect of microwave dehydration on saffron main metabolites (picrocrocin, safranal and crocetin esters) from Crocus sativus L. stigmas at three determinate powers and different time lapses was evaluated. The results showed that this dehydration process obtained similar or lower crocetin esters content, and after three months of storage, higher concentration was shown in treatments at 440 W for 36 s, 55 s, and 73 s; at 616 W for 90 s; and at 800 W for 20 s. Picrocrocin content was lower and safranal content was higher in all treatments compared to the control both before and after storage. Regarding to commercial quality, microwave dehydration obtained Category I of saffron according to International Standard Organization (ISO) 3632. After three months of storage, treatments at 616 W for 83 s and 800 W for 60 s obtained lower categories. The results obtained suggest that microwave dehydration is a suitable process for obtaining high quality saffron, 800 W with 6 lapses of 20 s being the best conditions studied.