33 research outputs found
A Non-Canonical E-Box Within the \u3cem\u3eMyoD\u3c/em\u3e Core Enhancer is Necessary for Circadian Expression in Skeletal Muscle
The myogenic differentiation 1 (MyoD) gene is a master regulator of myogenesis. We previously reported that the expression of MyoD mRNA oscillates over 24 h in skeletal muscle and that the circadian clock transcription factors, BMAL1 (brain and muscle ARNT-like 1) and CLOCK (circadian locomotor output cycles kaput), were bound to the core enhancer (CE) of the MyoD gene in vivo. In this study, we provide in vivo and in vitro evidence that the CE is necessary for circadian expression of MyoD in adult muscle. Gel shift assays identified a conserved non-canonical E-box within the CE that is bound by CLOCK and BMAL1. Functional analysis revealed that this E-box was required for full activation by BMAL1/CLOCK and for in vitro circadian oscillation. Expression profiling of muscle of CEloxP/loxP mice found approximately 1300 genes mis-expressed relative to wild-type. Based on the informatics results, we analyzed the respiratory function of mitochondria isolated from wild-type and CEloxP/loxP mice. These assays determined that State 5 respiration was significantly reduced in CEloxP/loxP muscle. The results of this work identify a novel element in the MyoD enhancer that confers circadian regulation to MyoD in skeletal muscle and suggest that loss of circadian regulation leads to changes in myogenic expression and downstream mitochondrial function
A non-canonical E-box within the MyoD core enhancer is necessary for circadian expression in skeletal muscle
The myogenic differentiation 1 (MyoD) gene is a master regulator of myogenesis. We previously reported that the expression of MyoD mRNA oscillates over 24 h in skeletal muscle and that the circadian clock transcription factors, BMAL1 (brain and muscle ARNT-like 1) and CLOCK (circadian locomotor output cycles kaput), were bound to the core enhancer (CE) of the MyoD gene in vivo. In this study, we provide in vivo and in vitro evidence that the CE is necessary for circadian expression of MyoD in adult muscle. Gel shift assays identified a conserved non-canonical E-box within the CE that is bound by CLOCK and BMAL1. Functional analysis revealed that this E-box was required for full activation by BMAL1/CLOCK and for in vitro circadian oscillation. Expression profiling of muscle of CEloxP/loxP mice found approximately 1300 genes mis-expressed relative to wild-type. Based on the informatics results, we analyzed the respiratory function of mitochondria isolated from wild-type and CEloxP/loxP mice. These assays determined that State 5 respiration was significantly reduced in CEloxP/loxP muscle. The results of this work identify a novel element in the MyoD enhancer that confers circadian regulation to MyoD in skeletal muscle and suggest that loss of circadian regulation leads to changes in myogenic expression and downstream mitochondrial function
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Can almond trees directly dictate their irrigation needs?
Many of California’s fruit and nut growers have already embraced more efficient irrigation systems (drip and microsprinkler) and adopted scientific irrigation-scheduling methods that closely match net applied water to evapotranspiration (ETc). Further improvements in irrigation efficiency may be possible by using regulated deficit irrigation (RDI) to purposely stress trees at specific times of the season. Tree-based RDI triggers for irrigation scheduling, such as stem water potential (SWP) and maximum daily trunk shrinkage (MDS), as opposed to soil and atmospheric measurements, have the major advantage of being directly linked to crop productivity. The current state of the art in plant-based scheduling is SWP and MDS, but adoption is hampered by the lack of field studies validating its effectiveness. We conducted an experiment in a commercial almond orchard to evaluate the suitability of MDS measurements as indicators for RDI management. Small, electronic sensors affixed to the tree trunks continuously recorded diameters from which MDS values were gleaned and used to schedule two RDI treatments. We found that with the less severe RDI regime, less water was applied relative to the cooperator’s nearly fully irrigated trees with no significant reduction in kernel size or other important almond parameters. In fact, the RDI regimes accelerated hull-split, decreased kernel water content and increased the nut-kernel percentage at harvest — all desirable almond results. We have demonstrated, for the first time in California, that RDI can be successfully scheduled based entirely on continuously recorded, tree-based electronic data. We believe that MDS measurements have some operational advantages over SWP, including lower labor costs and the ability to be directly incorporated into remotely operated, electronic controllers
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Insufficient spring irrigation increases abnormal splitting of pistachio nuts
Abnormal pistachio nuts, known as “early-split nuts,” have both the hull and shell split while still on the tree, exposing the kernel to invasion by insects and molds. Deficit irrigation of pistachio trees in April and May resulted in substantial increases in the formation of early-split nuts in late summer, while extreme deficit irrigation in July and August resulted in decreased formation. However, deficit irrigation during the period of shell hardening, mainly in June, did not affect early-split formation