Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
light sense [keywords]
- An analysis of the action of light on betalain synthesis in the seedling of Amaranthus caudatus, var. viridis. [Journal Article]
- Planta 1981 Jan; 151(1):81-7.
Accumulation of betalain (amaranthin) in the seedling of Amaranthus caudatus, var. viridis, is inducible by light. Since the apparent lag-phase of amaranthin accumulation after the onset of light is of the order of 3 h, light induction experiments could be performed up to 3 h after the onset of light without interference with actual synthesis. The intricate induction phenomena can be explained as follows: The inductive light operates through phytochrome and through a blue/UV photoreceptor ('cryptochrome'). A phytochrome-dependent 'High Irradiance Reaction' is of minor importance. However, there is a strong, specific interaction between the light effects mediated through phytochrome and cryptochrome in the sense that the 'extent of the reversible response' - (response obtained with a particular light treatment terminated with a saturating red light pulse) minus (response obtained with the same light treatment when terminated with a saturating 756 nm light pulse) -increases with increasing Pfr level and total fluence rate during the induction period. It is concluded that light induced amaranthin synthesis is, in fact, a convenient biochemical model system of photomorphogenesis in the case when phytochrome and cryptochrome operate simultaneously in mediating photomorphogenesis.
- Reduced phototropism in pks mutants may be due to altered auxin-regulated gene expression or reduced lateral auxin transport. [JOURNAL ARTICLE]
- Plant J 2013 Nov 29.
Phototropism allows plants to orient their photosynthetic organs towards the light. In Arabidopsis, phototropins 1 and 2 sense directional blue light with phot1 triggering phototropism in response to low fluence rates, while both phot1 and phot2 mediate this response in higher light. Phototropism results from asymmetric growth in the hypocotyl elongation zone that depends on an auxin gradient across the embryonic stem. How phototropin activation leads to this growth response is still poorly understood. Members of the Phytochrome Kinase Substrate (PKS) family may act early in this pathway because PKS1, PKS2 and PKS4 are needed for a normal phototropic response and they associate with phot1 in vivo. Here we show that PKS proteins are needed both for phot1 and phot2-mediated phototropism. The phototropic response is conditioned by the developmental asymmetry of dicotyledonous seedlings with a faster growth reorientation when the cotyledons face away from the light compared to seedlings with the cotyledons facing the light. The molecular basis for this developmental effect on phototropism is unknown, here we show that PKS proteins play a role at the interface between development and phototropism. Moreover we present evidence for a role of PKS genes in hypocotyl gravi-reorientation that is independent of photoreceptors. pks mutants have normal levels of auxin and normal polar auxin transport however they show altered expression patterns of auxin marker genes. This suggests that PKS proteins are involved in auxin signaling and/or lateral auxin redistribution. This article is protected by copyright. All rights reserved.
- Signatures of natural selection and ecological differentiation in microbial genomes. [Journal Article]
- Adv Exp Med Biol 2014.:339-59.
We live in a microbial world. Most of the genetic and metabolic diversity that exists on earth - and has existed for billions of years - is microbial. Making sense of this vast diversity is a daunting task, but one that can be approached systematically by analyzing microbial genome sequences. This chapter explores how the evolutionary forces of recombination and selection act to shape microbial genome sequences, leaving signatures that can be detected using comparative genomics and population-genetic tests for selection. I describe the major classes of tests, paying special attention to their relative strengths and weaknesses when applied to microbes. Specifically, I apply a suite of tests for selection to a set of closely-related bacterial genomes with different microhabitat preferences within the marine water column, shedding light on the genomic mechanisms of ecological differentiation in the wild. I will focus on the joint problem of simultaneously inferring the boundaries between microbial populations, and the selective forces operating within and between populations.
- Recovery of sensory and supraspinal control of leg movement in peoples with chronic paraplegia: a case series. [JOURNAL ARTICLE]
- Arch Phys Med Rehabil 2013 Nov 19.
To report on unexpected findings in four patients with chronic paraplegia who underwent laparoscopic implantation of neuroprosthresis (LION procedure) in the pelvic lumbosacral nerves.Observational case series.Tertiary referral unit specialized in advanced gynecological surgery and neuropelveology.Three patients with incomplete ASIA impairment scale (AIS) B (n=2) and AIS C (n=1) spinal cord injury (SCI) and one with flaccid complete chronic SCI (AIS A).Functional electrical stimulation (FES)-assisted locomotor training and continuous low-frequency pelvic-lumbosacral neuromodulation.Change in ASIA Lower Extremity Motor Scores (LEMS), ASIA sensory scores (ASS) for light touch and pinprick sensation, and Walking Index for Spinal Cord Injury (WISCI) scores.All four patients developed progressive recovery of some sensory and voluntary motor functions below the lesions. Three are currently capable of voluntary weight-bearing standing and walking a few meters with a walker, without FES. The first patient with the longest follow up is even capable of electrically-assisted standing/walking with two crutches without braces or assistance for a distance of about 900 meters, and of weight-bearing standing and walking for 30 meters with a walker, without stimulation.We report unexpected sensory and locomotor recovery in four paraplegics with SCI. Our findings suggest that FES-assisted locomotor training with continuous low-frequency pelvic nerve stimulation in SCI patients may induce changes that affect the central pattern generator and allow supra- and infraspinal inputs to engage residual spinal pathways.
- Genomic analysis reveals key aspects of prokaryotic symbiosis in the phototrophic consortium 'Chlorochromatium aggregatum' [JOURNAL ARTICLE]
- Genome Biol 2013 Nov 22; 14(11):R127.
'Chlorochromatium aggregatum' is a phototrophic consortium, a symbiosis that may represent the highest degree of mutual interdependence between two unrelated bacteria not associated with a eukaryotic host. 'Chlorochromatium aggregatum' is a motile, barrel-shaped aggregate formed from a single cell of "Candidatus Symbiobacter mobilis," a polarly flagellated, non-pigmented, heterotrophic bacterium, which is surrounded by approximately 15 epibiont cells of Chlorobium chlorochromatii, a non-motile photolithoautotrophic green sulfur bacterium.We analyzed the complete genome sequences of both organisms to understand the basis for this symbiosis. Chl. chlorochromatii has acquired relatively few symbiosis-specific genes; most acquired genes are predicted to modify the cell wall or function in cell-cell adhesion. In striking contrast, "Ca. S. mobilis" appears to have undergone massive gene loss, is probably no longer capable of independent growth, and thus may only reproduce when consortia divide. A detailed model for the energetic and metabolic bases of the dependency of "Ca. S. mobilis" on Chl. chlorochromatii is described.Genomic analyses suggest that three types of interactions lead to a highly sophisticated relationship between these two organisms. Firstly, extensive metabolic exchange, involving carbon, nitrogen, and sulfur sources as well as vitamins, occurs from the epibiont to the central bacterium. Secondly, "Ca. S. mobilis" can sense and move towards light and sulfide, resources that only directly benefit the epibiont. Thirdly, electron cycling mechanisms, particularly those mediated by quinones and potentially involving shared protonmotive force, could provide an important basis for energy exchange in this and other symbiotic relationships.
- Synthesis of mesoporous silica-gel core-shell structural microparticles and their multiple drug delivery. [JOURNAL ARTICLE]
- Drug Deliv 2013 Nov 25.
Abstract Context: Release of two drugs safely and independently should be necessary in medical or reaction engineering fields to overcome many complex problems such as multi-drug resistance in treatment of disease. Objectives: Core-shell structural microparticles that can load/release two drugs simultaneously are designed and prepared. Materials: The microparticles are composed of mesoporous silica core and hyaluronate (HA)/poly (N-isopropylacrylamide) hybrid gel shell. Methods: The synthesis processes are monitored by powder x-ray diffraction and Fourier transform infrared spectroscopy. The properties of microparticles are characterized by nuclear magnetic resonance, dynamic light scattering and transmission electron microscope methods. Two kinds of drugs are loaded into the mesoporous-core and gel-shell, respectively, and then released under various conditions. Results: The microparticles show uniform spherical shapes with core-shell structures. When temperature is higher than the lower critical solution temperature, the microparticles shrink abruptly and assemble. The drug release rates have been found to depend on the concentration of the microparticle suspensions and pH of the release medium. Discussion: The swellability of the microparticles are controlled by the HA size and gel crosslink density; and the main effect factors on drug releasing behavior are the drug properties and drug diffusion ability. Conclusion: The experimental results confirmed different drugs could be safely loaded into the core-shell structural microparticles and released independently, which might be potential carriers for drugs or catalysts. These microparticles would be expected to make sense for applying in medical or reaction engineering fields.
- Interpretation of Digital Chest Radiographs: Comparison of Light Emitting Diode versus Cold Cathode Fluorescent Lamp Backlit Monitors. [Journal Article]
- Korean J Radiol 2013 Nov; 14(6):968-76.
To compare the diagnostic performance of light emitting diode (LED) backlight monitors and cold cathode fluorescent lamp (CCFL) monitors for the interpretation of digital chest radiographs.We selected 130 chest radiographs from health screening patients. The soft copy image data were randomly sorted and displayed on a 3.5 M LED (2560 × 1440 pixels) monitor and a 3 M CCFL (2048 × 1536 pixels) monitor. Eight radiologists rated their confidence in detecting nodules and abnormal interstitial lung markings (ILD). Low dose chest CT images were used as a reference standard. The performance of the monitor systems was assessed by analyzing 2080 observations and comparing them by multi-reader, multi-case receiver operating characteristic analysis. The observers reported visual fatigue and a sense of heat. Radiant heat and brightness of the monitors were measured.Measured brightness was 291 cd/m(2) for the LED and 354 cd/m(2) for the CCFL monitor. Area under curves for nodule detection were 0.721 ± 0.072 and 0.764 ± 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 ± 0.073 and 0.844 ± 0.068 (p = 0.145), respectively. There were no significant differences in interpretation time (p = 0.446) or fatigue score (p = 0.102) between the two monitors. Sense of heat was lower for the LED monitor (p = 0.024). The temperature elevation was 6.7℃ for LED and 12.4℃ for the CCFL monitor.Although the LED monitor had lower maximum brightness compared with the CCFL monitor, soft copy reading of the digital chest radiographs on LED and CCFL showed no difference in terms of diagnostic performance. In addition, LED emitted less heat.
- Therapeutic Relationship Between Male Nursing Students and Female Patients. [JOURNAL ARTICLE]
- Am J Mens Health 2013 Nov 20.
This article explores the therapeutic relationship between male nursing students and female patients, through the use of autobiography in a qualitative approach. For this study, 18 male nursing students enrolled in master's and bachelor's programs in Hong Kong were recruited. They were asked to make records in a diary and draw pictures of their therapeutic relationship with female patients from their clinical experiences and then participate in a focus group interview. Content analysis was carried out on the collected data. The essential factors influencing the development of a therapeutic relationship were found to be gender, symbolic meanings, and career features. Good experiences were also discussed. The results shed light on the experiences of male nursing students and how they make sense of their therapeutic relationship with female patients.
- A (18)F-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury. [Journal Article]
- J Am Chem Soc 2013 Dec 4; 135(48):18012-5.
Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.
- Regulation of Light Harvesting in the Green Alga Chlamydomonas reinhardtii: The C-Terminus of LHCSR Is the Knob of a Dimmer Switch. [JOURNAL ARTICLE]
- J Am Chem Soc 2013 Nov 26.
Feedback mechanisms that dissipate excess photoexcitations in light-harvesting complexes (LHCs) are necessary to avoid detrimental oxidative stress in most photosynthetic eukaryotes. Here we demonstrate the unique ability of LHCSR, a stress-related LHC from the model organism Chlamydomonas reinhardtii, to sense pH variations, reversibly tuning its conformation from a light-harvesting state to a dissipative one. This conformational change is induced exclusively by the acidification of the environment, and the magnitude of quenching is correlated to the degree of acidification of the environment. We show that this ability to respond to different pH values is missing in the related major LHCII, despite high structural homology. Via mutagenesis and spectroscopic characterization, we show that LHCSR's uniqueness relies on its peculiar C-terminus subdomain, which acts as a sensor of the lumenal pH, able to tune the quenching level of the complex.