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ABSTRACT: The ongoing debate of whether the aging process is driven by stochastic events or regulated by biological mechanisms is nearly a century old. While numerous studies strongly support the idea that signaling and metabolic pathways govern the pace of aging, other findings suggest that a sequence of stochastic events underlies the progression of this process. Two recent developments in the field of aging provide affirmation to the notion that aging has regulated aspects. First, the collapse of proteome integrity (proteostasis), a prominent aspect of aging, occurs within a surprisingly narrow time window, shortly after transition of the nematode Caenorhabditis elegans to adulthood. In addition, inter-tissue communication was found to play key roles in proteostasis maintenance across tissues and to affect the worm's lifespan. Here we briefly review the current knowledge in the field and delineate the experimental evidence which indicates that aging is a complex, multi-factorial process whose pace is determined by both random events and regulatory mechanisms.Frontiers in Genetics 03/2015; 6:80. DOI:10.3389/fgene.2015.00080
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ABSTRACT: Drosophila phototransduction is a model system for the ubiquitous phosphoinositide signaling. In complete darkness, spontaneous unitary current events (dark bumps) are produced by spontaneous single Gqα activation, while single-photon responses (quantum bumps) arise from synchronous activation of several Gqα molecules. We have recently shown that most of the spontaneous single Gqα activations do not produce dark bumps, because of a critical phospholipase Cβ (PLCβ) activity level required for bump generation. Surpassing the threshold of channel activation depends on both PLCβ activity and cellular [Ca(2+)], which participates in light excitation via a still unclear mechanism. We show here that in IP3 receptor (IP3R)-deficient photoreceptors, both light-activated Ca(2+) release from internal stores and light sensitivity were strongly attenuated. This was further verified by Ca(2+) store depletion, linking Ca(2+) release to light excitation. In IP3R-deficient photoreceptors, dark bumps were virtually absent and the quantum-bump rate was reduced, indicating that Ca(2+) release from internal stores is necessary to reach the critical level of PLCβ catalytic activity and the cellular [Ca(2+)] required for excitation. Combination of IP3R knockdown with reduced PLCβ catalytic activity resulted in highly suppressed light responses that were partially rescued by cellular Ca(2+) elevation, showing a functional cooperation between IP3R and PLCβ via released Ca(2+). These findings suggest that in contrast to the current dogma that Ca(2+) release via IP3R does not participate in light excitation, we show that released Ca(2+) plays a critical role in light excitation. The positive feedback between PLCβ and IP3R found here may represent a common feature of the inositol-lipid signaling. Copyright © 2015 the authors 0270-6474/15/352530-17$15.00/0.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 02/2015; 35(6):2530-46. DOI:10.1523/JNEUROSCI.3933-14.2015
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ABSTRACT: Plant leaves develop in accordance with a common basic program, which is flexibly adjusted to the species, developmental stage and environment. Two key stages of leaf development are morphogenesis and differentiation. In the case of compound leaves, the morphogenesis stage is prolonged as compared to simple leaves, allowing for the initiation of leaflets. Here, we review recent advances in the understanding of how plant hormones and transcriptional regulators modulate compound leaf development, yielding a substantial diversity of leaf forms, focusing on four model compound leaf organisms: cardamine (Cardamine hirsuta), tomato (Solanum lycopersicum), medicago (Medicago truncatula) and pea (Pisum sativum).Current Opinion in Plant Biology 02/2015; 23. DOI:10.1016/j.pbi.2014.10.007
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