Suppression of starch synthase I(SSI) by RNA interference alters starch biosynthesis and amylopectin chain distribution in rice plants subjected to high temperature

Based on known cDNAs of rice starch synthase isoforms,we constructed dsRNA interference vectors for starch synthase I(SSI)to produce transgenic plants containing starch with a moderately high amylose content.We investigated the effect of SSI suppression on grain quality traits,starch biosynthesis,and amylopectin chain distribution in rice plants exposed to two different temperature regimes.The activities and transcripts of BEs,DBEs,and other SS isoforms were further investigated to clarify the effect of SSI suppression on these key enzymes and their specific isoforms under different temperature treatments.Suppression of SSI by RNAi altered grain starch component and amylopectin chain distribution,but it exerted only a slight effect on total starch content(%)and accumulation amount(mg kernel?1)and on starch granule morphology and particle size distribution.Under normal temperature(NT),insignificant differences in kernel weight,chalky kernel proportion,chalky degree,and starch granule morphology between SSI-RNAi line and its wild type(WT)were observed.However,amylose content(AC)level and granule-bound starch synthase(GBSS)activity in rice endosperms were markedly increased by SSI-RNAi suppression.The chalky kernel proportion and chalky degree of SSIRNAi lines were significantly higher than those of WT under high temperature(HT)exposure at filling stage.Inhibition of SSI by RNAi affected amylopectin chain distribution and raised starch gelatinization temperature(GT)in two ways:directly from the SSI deficiency itself and indirectly by reducing BEIIb amounts in an SSI-deficient background.The deficiency of SSI expression led to an alteration in the susceptibility of grain chalkiness occurrence and starch gelatinization temperature to HT exposure,owing to a pleiotropic effect of SSI deficiency on the expression of other genes associated with starch biosynthesis.

Concurrent photoacoustic and ultrasound microscopy with a coaxial dual-element ultrasonic transducer

Simultaneous photoacoustic and ultrasound(PAUS)imaging has attracted increasing attention in biomedical research to probe the optical and mechanical properties of tissue.However,the resolution for majority of the existing PAUS systems is on the order of 1 mm as the majority are designed for clinical use with low-frequency US detection.Here we developed a concurrent PAUS microscopy that consists of optical-resolution photoacoustic microscopy(OR-PAM)and high-frequency US pulse-echo imaging.This dual-modality system utilizes a novel coaxial dual-element ultrasonic transducer(DE-UST)and provides anatomical and functional information with complementary contrast mechanisms,achieving a spatial resolution of 7μm for PA imaging and 106μm for US imaging.We performed phantom studies to validate the system’s performance.The vasculature of a mouse’s hind paw was imaged to demonstrate the potential of this hybrid system for biomedical applications.

Highly Integrated Multiplexing and Buffering Electronics for Large Aperture Ultrasonic Arrays

Large aperture ultrasonic arrays can be implemented by tiling together multiple pretested modules of high-density acoustic arrays with closely integrated multiplexing and buffering electronics to form a larger aperture with high yield.These modular arrays can be used to implement large 1.75D array apertures capable of focusing in elevation for uniform slice thickness along the axial direction which can improve image contrast.An important goal for large array tiling is obtaining high yield and sensitivity while reducing extraneous image artifacts.We have been developing tileable acoustic-electric modules for the implementation of large array apertures utilizing Application Specific Integrated Circuits(ASICs)implemented using 0.35μm high voltage(50 V)CMOS.Multiple generations of ASICs have been designed and tested.The ASICs were integrated with high-density transducer arrays for acoustic testing and imaging.The modules were further interfaced to a Verasonics Vantage imaging system and were used to image industry standard ultrasound phantoms.The first-generation modules comprise ASICs with both multiplexing and buffering electronics on-chip and have demonstrated a switching artifact which was visible in the images.A second-generation ASIC design incorporates low switching injection circuits which effectively mitigate the artifacts observed with the first-generation devices.Here,we present the architecture of the two ASIC designs and module types as well imaging results that demonstrate reduction in switching artifacts for the second-generation devices.

Erratum to “Highly Integrated Multiplexing and Buffering Electronics for Large Aperture Ultrasonic Arrays”

In the article titled“Highly Integrated Multiplexing and Buffering Electronics for Large Aperture Ultrasonic Arrays”[1],there was an error in figure 7.The figure should show as per the submitted files.

ecent Advances in the Science of Burst Wave Lithotripsy and Ultrasonic Propulsion

Objective.Retinal degeneration involving progressive deterioration and loss of function of photoreceptors is a major cause of permanent vision loss worldwide.Strategies to treat these incurable conditions incorporate retinal prostheses via electrically stimulating surviving retinal neurons with implanted devices in the eye,optogenetic therapy,and sonogenetic therapy.Existing challenges of these strategies include invasive manner,complex implantation surgeries,and risky gene therapy.Methods and Results.Here,we show that direct ultrasound stimulation on the retina can evoke neuron activities from the visual centers including the superior colliculus and the primary visual cortex(V1),in either normal-sighted or retinal degenerated blind rats in vivo.The neuron activities induced by the customized spherically focused 3.1 MHz ultrasound transducer have shown both good spatial resolution of 250μm and temporal resolution of 5 Hz in the rat visual centers.An additional customized 4.4 MHz helical transducer was further implemented to generate a static stimulation pattern of letter forms.Conclusion.Our findings demonstrate that ultrasound stimulation of the retina in vivo is a safe and effective approach with high spatiotemporal resolution,indicating a promising future of ultrasound stimulation as a novel and noninvasive visual prosthesis for translational applications in blind patients.

Development of Moderate Intensity Focused Ultrasound(MIFU)for Ocular Drug Delivery

The purpose of this study is to develop a method for delivering antiinflammatory agents of high molecular weight(e.g.,Avastin)into the posterior segment that does not require injections into the eye(i.e.,intravitreal injections;IVT).Diseases affecting the posterior segment of the eye are currently treated with monthly to bimonthly intravitreal injections,which can predispose patients to severe albeit rare complications like endophthalmitis,retinal detachment,traumatic cataract,and/or increased intraocular.In this study,we show that one time moderate intensity focused ultrasound(MIFU)treatment can facilitate the penetration of large molecules across the scleral barrier,showing promising evidence that this is a viable method to deliver high molecular weight medications not invasively.To validate the efficacy of the drug delivery system,IVT injections of vascular endothelial growth factor(VEGF)were used to create an animal model of retinopathy.The creation of this model allowed us to test anti-VEGF medications and evaluate the efficacy of the treatment.In vivo testing showed that animals treated with our MIFU device improved on the retinal tortuosity and clinical dilation compared to the control group while evaluating fluorescein angiogram(FA)Images.

Real-time whole-brain imaging of hemodynamics and oxygenation at micro-vessel resolution with ultrafast wide-field photoacoustic microscopy

High-speed high-resolution imaging of the whole-brain hemodynamics is critically important to facilitating neurovascular research.High imaging speed and image quality are crucial to visualizing real-time hemodynamics in complex brain vascular networks,and tracking fast pathophysiological activities at the microvessel level,which will enable advances in current queries in neurovascular and brain metabolism research,including stroke,dementia,and acute brain injury.Further,real-time imaging of oxygen saturation of hemoglobin(sO_(2))can capture fast-paced oxygen delivery dynamics,which is needed to solve pertinent questions in these fields and beyond.Here,we present a novel ultrafast functional photoacoustic microscopy(UFF-PAM)to image the whole-brain hemodynamics and oxygenation.UFF-PAM takes advantage of several key engineering innovations,including stimulated Raman scattering(SRS)based dual-wavelength laser excitation,water-immersible 12-facet-polygon scanner,high-sensitivity ultrasound transducer,and deep-learning-based image upsampling.A volumetric imaging rate of 2 Hz has been achieved over a field of view(FOV)of 11×7.5×1.5 mm^(3) with a high spatial resolution of~10 μm.Using the UFF-PAM system,we have demonstrated proof-of-concept studies on the mouse brains in response to systemic hypoxia,sodium nitroprusside,and stroke.We observed the mouse brain's fast morphological and functional changes over the entire cortex,including vasoconstriction,vasodilation,and deoxygenation.More interestingly,for the first time,with the whole-brain FOV and micro-vessel resolution,we captured the vasoconstriction and hypoxia simultaneously in the spreading depolarization(SD)wave.We expect the new imaging technology will provide a great potential for fundamental brain research under various pathological and physiological conditions.

PZT FILM GENERATOR DRIVEN BY ULTRASONIC WAVE

Energy harvesting was demonstrated in hydrothermal PZT nanocrystal films driven by ultra-sound.With high temperature sintering and solution infiltration,PZT films with nanograin sizewas found to exhibit bulk-like properties such as large remnant polarization of 42μC/cm^(2).Withthe bulk-like properties,a packaged PZT film device was demonstrated to be capable of convertingmechanical energy carried by the ultrasonic wave into electrical energy in a reliable and efficient way.The result suggests an alternative potential solution for energy harvesting application.

Study on the pyroelectric properties of PLT/P(VDF-TrFE) nanocomposites

Lead lanthanum titanate (PLT) nanocrystalline powder prepared by the sol_gel process was incorporated into a polyvinylidene fluoride/trifluoroethylene (P(VDF_TrEF)) copolymer matrix to form PLT/P(VDF_TrFE) nanocomposites. The permittivities (ε) of the nanocomposites as a function of volume fraction of ceramic were modeled using the Bruggeman model. The pyroelectric coefficients (p) and figure of merit (p/ε) were measured as functions of the poling field E. The nanocomposite has p and p/ε values higher than those of the copolymer, and has good potential in pyroelectric applications.