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light sense [keywords]
- Relative contribution of shoot and ear photosynthesis to grain filling in wheat under good agronomical conditions assessed by differential organ δ13C. [JOURNAL ARTICLE]
- J Exp Bot 2014 Jul 22.
During grain filling in C3 cereals, the shoot (particularly the flag leaf) and the ear are believed to play major roles as sources of assimilates. However, both the cost and the intrusive nature of most of the methodologies available to investigate this have prevented conclusive results being obtained. This study compared the carbon isotope composition (δ(13)C) in its natural abundance in mature kernels with the δ(13)C of the water-soluble fraction of the peduncle, glumes, and awns to assess the relative contribution of the shoot (understood as the whole set of photosynthetic organs below the peduncle) and ear to grain filling in a set of highly productive wheat lines from the International Maize and Wheat Improvement Center, Mexico, under good agronomic conditions. In overall terms, the contribution of the ear was greater in comparison with that of the shoot. The specific contribution of the flag leaf blade to grain filling was also assessed by comparing the δ(13)C of grains with the δ(13)C of the water-soluble fraction of the flag leaf and the awns. The contribution of the flag leaf was minor, ranging between 3 and 18%. Complementary analyses performed such as gas-exchange rates and the accumulated water-soluble carbohydrates in both organs and light intercepted by the canopy at different strata suggested that the ear has a photosynthetic capacity at least comparable to that of the flag leaf. In this sense, selection for a higher contribution of ear photosynthesis to grain yield in breeding programmes could be addressed with the use of stable isotopes.
- Code blue: Acinetobacter baumannii, a nosocomial pathogen with a role in the oral cavity. [JOURNAL ARTICLE]
- Mol Oral Microbiol 2014 Jul 22.
Actinetobacter baumannii is an important nosocomial pathogen which can cause a wide range of serious conditions including pneumonia, meningitis, necrotizing fasciitis and sepsis. A. baumanni is also a major cause of wound infections in military personnel injured during the conflicts in Afghanistan and Iraq, leading to its popular nickname of 'Iraqibacter'. Contributing to its success in clinical setting is resistance to environmental stresses such as desiccation and disinfectants. Moreover, in recent years there has been a dramatic increase in the number of A. baumannii strains with resistance to multiple antibiotic classes. A. baumannii is an inhabitant of oral biofilms which can act as a reservoir for pneumonia and chronic obstructive pulmonary disease. Subgingival colonization by A. baumannii increases the risk of refractory periodontitis. Pathogenesis of the organism involves adherence, biofilm formation, and iron acquisition. In addition, A. baumannii can induce apoptotic cell death in epithelial cells and kill hyphal forms of Candida albicans. Virulence factors that have been identified include pili, the outer membrane protein OmpA, phospholipases, and extracellular polysaccharide. A. baumannii can sense blue light through a blue-light sensing using flavin (BLUF) domain protein, BlsA. The resulting conformational change in BlsA leads to changes in gene expression, including virulence genes. This article is protected by copyright. All rights reserved.
- Using a microbial physiologic and genetic approach to investigate how bacteria sense physical stimuli. [JOURNAL ARTICLE]
- Biochem Mol Biol Educ 2014 Jul 23.
A laboratory exercise was designed to illustrate how physical stimuli such as temperature and light are sensed and processed by bacteria to elaborate adaptive responses. In particular, we use the well-characterized Des pathway of Bacillus subtilis to show that temperature modulates gene expression, resulting ultimately in modification of the levels of unsaturated fatty acids required to maintain proper membrane fluidity at different temperatures. In addition, we adapt recent findings concerning the modulation by light of traits related to virulence such as motility and biofilm formation in the chemotropic bacterium Acinetobacter baumannii. Beyond the theoretical background that this activity provides regarding sensing of environmental stimuli, the experimental setup includes approaches derived from classic genetics, microbiology, and biochemistry. The incorporation of these kind of teaching and training activities in middle-advanced Microbiology or Bacterial Genetics courses promotes acquisition of general and specific techniques and improves student's comprehension of scientific literature and research. © 2014 by The International Union of Biochemistry and Molecular Biology, 42(4):305-322, 2014.
- Bare fiber photodynamic therapy using porfimer sodium for esophageal disease. [JOURNAL ARTICLE]
- Photodiagnosis Photodyn Ther 2006 Jun; 3(2):87-92.
During Digestive Disease Week 2005 in Chicago, Illinois, our group of 10 gastrointestinal photodynamic therapists met to discuss variations in procedural technique and treatment protocols. An extensive review of the use of photodynamic therapy (PDT) for esophageal disease has recently been published elsewhere [Wolfsen HC. Present status of photodynamic therapy for high-grade dysplasia in Barrett's esophagus. J Clin Gastroenterol 2005;39(3):189-202]. This report, based mostly on clinical experience and common sense rather than evidence-based medicine, is a detailed discussion of pragmatic issues. In summary, our centers treat patients with Barrett's dysplasia, Barrett's or squamous cell carcinoma using the photosensitizer porfimer sodium (2mg/kg total body weight) and bare fiber PDT (no fiber centering devices). Aggressive suppression of gastric acid is uniformly emphasized. The most common technique variables were the light energy source, light dosimetry and the amount of Barrett's mucosa treated during a course of PDT. Standardization of porfimer sodium PDT procedures and light dosimetry may enhance treatment outcomes.
- Photodiagnosis and fluorescence imaging in clinical practice. [JOURNAL ARTICLE]
- Photodiagnosis Photodyn Ther 2004 May; 1(1):9-12.
For cancer diagnosis clinicians rely upon histo pathological preparations in their broadest sense and the characteristic microscopic features which represent malignant changes. Standard method of in-vivo sampling (biopsy) uses white light indicating abnormal tissue. The manner in which light interacts with a specific tissue type is dictated by the wavelength dependent scattering and absorbtion properties. In the UV and visible part of the spectrum the tissue optical properties are dominated by the endogenous chromophores which is different for normal/abnormal tissue. It follows that abnormal tissue, absorbs light and fluoresces differently to normal tissue at specific light wavelengths. Autofluorescence takes advantage of this principle. Enhanced fluorescence employs exogenous markers to produce better definition. Fluorescence imaging has become an important diagnostic tool to highlight cancer at an early stage of development and/or to guide biopsy from representative samples.
- Making Sense of Brownian Motion: Colloid Characterisation by Dynamic Light Scattering. [JOURNAL ARTICLE]
- Langmuir 2014 Jul 22.
Dynamic light scattering has evolved as a fast, convenient tool for particle size analysis of non-interacting spherical colloids. In this instructional review, we discuss the basic principle, data analysis and important precautions to be taken while analysing colloids using DLS. The effect of particle interaction, polydispersity, anisotropy, light absorption etc on measured diffusion coefficient is discussed. New developments in this area such as diffusing wave spectroscopy, particle tracking analysis, microrheological studies using DLS etc are discussed in a manner that can be understood by a beginner.
- Light and pheromone-sensing neurons regulates cold habituation through insulin signalling in Caenorhabditis elegans. [JOURNAL ARTICLE]
- Nat Commun 2014.:4412.
Temperature is a critical environmental stimulus that has a strong impact on an organism's biochemistry. Animals can respond to changes in ambient temperature through behaviour or altered physiology. However, how animals habituate to temperature is poorly understood. The nematode C. elegans stores temperature experiences and can induce temperature habituation-linked cold tolerance. Here we show that light and pheromone-sensing neurons (ASJ) regulate cold habituation through insulin signalling. Calcium imaging reveals that ASJ neurons respond to temperature. Cold habituation is abnormal in a mutant with impaired cGMP signalling in ASJ neurons. Insulin released from ASJ neurons is received by the intestine and neurons regulating gene expression for cold habituation. Thus, temperature sensation in a light and pheromone-sensing neuron produces a robust effect on insulin signalling that controls experience-dependent temperature habituation.
- Asteatotic Eczema in Hypoesthetic Skin: A Case Series. [JOURNAL ARTICLE]
- JAMA Dermatol 2014 Jul 16.
Asteatotic eczema (eczema craquelé, xerotic eczema) occurs most frequently in areas of dehydrated skin, most often during the winter months when decreased humidity results in increased water loss from the stratum corneum. We present 5 cases in which asteatotic eczema was found outside of its normal distribution, within desensitized skin and scars.Five patients with a history of trauma and scar formation presented with erythematous, dry plaques with fine crackling involving hypoesthetic skin. Each of the 5 patients had classic asteatotic eczema skin findings, the only commonality being hypoesthesia. Borders of the hypoesthetic skin were identified using light touch and compared with the regions affected by asteatotic eczema. In all cases, the skin affected by asteatotic eczema was within the hypoesthetic areas.Asteatotic eczema developing on skin with altered sensation is an underreported condition. Prompt recognition and treatment may lead to a more efficient patient encounter and alleviate unnecessary patient stress.
- More than one world, more than one health: Re-configuring interspecies health. [JOURNAL ARTICLE]
- Soc Sci Med 2014 Jul 4.
'One World One Health' (OWOH), 'One Medicine' and 'One Health' are all injunctions to work across the domains of veterinary, human and environmental health. In large part they are institutional responses to growing concerns regarding shared health risks at the human, animal and environmental interfaces. Although these efforts to work across disciplinary boundaries are welcome, there are also risks in seeking unity, not least the tendency of one health visions to reduce diversity and to under-value the local, contingent and practical engagements that make health possible. This paper uses insights from Geography and Science and Technology Studies along with multi-sited and multi-species qualitative fieldwork on animal livestock and zoonotic influenzas in the UK, to highlight the importance of those practical engagements. After an introduction to one health, I argue that there is a tendency in OWOH visions to focus on contamination and transmission of pathogens rather than the socio-economic configuration of disease and health, and this tendency conforms to or performs what sociologist John Law calls a one world metaphysics. Following this, three related field cases are used to demonstrate that health is dependent upon a patchwork of practices, and is configured in practice by skilled people, animals, micro-organisms and their social relations. From surveillance for influenza viruses to tending animals, good health it turns out is dependent on an ability to construct common sense from a complex of signs, responses and actions. It takes, in other words, more than one world to make healthy outcomes. In light of this, the paper aims to, first, loosen any association between OWOH and a one world-ist metaphysics, and, second, to radicalize the inter-disciplinary foundations of OWOH by both widening the scope of disciplinarity as well as attending to how different knowledges are brought together.
- An electromagnetic field disrupts negative geotaxis in Drosophila via a CRY-dependent pathway. [Journal Article]
- Nat Commun 2014.:4391.
Many higher animals have evolved the ability to use the Earth's magnetic field, particularly for orientation. Drosophila melanogaster also respond to electromagnetic fields (EMFs), although the reported effects are quite modest. Here we report that negative geotaxis in flies, scored as climbing, is disrupted by a static EMF, and this is mediated by cryptochrome (CRY), the blue-light circadian photoreceptor. CRYs may sense EMFs via formation of radical pairs of electrons requiring photoactivation of flavin adenine dinucleotide (FAD) bound near a triad of Trp residues, but mutation of the terminal Trp in the triad maintains EMF responsiveness in climbing. In contrast, deletion of the CRY C terminus disrupts EMF responses, indicating that it plays an important signalling role. CRY expression in a subset of clock neurons, or the photoreceptors, or the antennae, is sufficient to mediate negative geotaxis and EMF sensitivity. Climbing therefore provides a robust and reliable phenotype for studying EMF responses in Drosophila.