Eumelanins and pheomelanins: characterization by electron spin resonance spectroscopy

Synthetic dopa melanin and cysteinyldopa melanin have different electron spin resonance spectra. Data are reported for mixtures of these melanins and for dopa-cysteinyldopa copolymers, which are spectroscopically similar. A simple parameterization of the spectra allows estimation of the relative amounts of (i) dopa melanin and cysteinyldopa melanin in mixtures and of (ii) dopa and cysteinyldopa incorporated into copolymers. Several natural eumelanins and pheomelanins have been characterized and shown to be copolymers.     

Fluorinated molecule as a tracer: difluoroserotonin in human platelets mapped by electron energy-loss spectroscopy

The intracellular distribution of fluorine has been delineated in human platelets incubated with 4,6-difluoroserotonin, utilizing a scanning-transmission electron microscope equipped with an energy-loss spectrometer. Discrete intracellular structures corresponding in location to dense bodies contained high concentrations of fluorine. Electron energy-loss spectroscopy, which apparently can detect less than 10(-20) gram of fluorine in an area of 10 square nonometers, can thus localize fluorinated tracer molecules with biological activity.     

Transfer of a protein encoded by a single nucleus to nearby nuclei in multinucleated myotubes

Specialized regions of muscle fibers may result from differential gene expression within a single fiber. In order to investigate the range of action of individual nuclei in multinucleated myotubes, C2 myoblasts were transfected to obtain stable cell lines that express a reporter protein that is targeted to the nucleus. Hybrid myotubes were then formed containing one or a few transfected nuclei as well as a large number of nuclei from the parental strain. In order to determine how far the products of a single nucleus extend, transfected nuclei were labeled with [3H]thymidine before fusion and the myotubes were stained to identify the reporter protein. In such myotubes the fusion protein was not confined to its nucleus of origin, but was restricted to nearby nuclei.     

Tunneling into a single magnetic atom: spectroscopic evidence of the kondo resonance

The Kondo effect arises from the quantum mechanical interplay between the electrons of a host metal and a magnetic impurity and is predicted to result in local charge and spin variations around the magnetic impurity. A cryogenic scanning tunneling microscope was used to spatially resolve the electronic properties of individual magnetic atoms displaying the Kondo effect. Spectroscopic measurements performed on individual cobalt atoms on the surface of gold show an energetically narrow feature that is identified as the Kondo resonance-the predicted response of a Kondo impurity. Unexpected structure in the Kondo resonance is shown to arise from quantum mechanical interference between the d orbital and conduction electron channels for an electron tunneling into a magnetic atom in a metallic host.     

From knowing to controlling: a path from genomics to drugs using small molecule probes

The National Cancer Institute Initiative in Chemical Genetics is designed to encourage the development of small molecular probes. The probes are useful for activating or inactivating protein functions, thereby providing resources that help discern the functions of gene products in normal and disease cells, as well as in tissues. This initiative includes "ChemBank," a suite of informatics tools and databases aimed at promoting the development and use of chemical genetics by scientists worldwide. The information generated with such tools should provide a critical link from genomic discovery to drug development.     

High-density electron anions in a nanoporous single crystal: [Ca24Al28O64]4+(4e-)

We removed approximately 100% of clathrated oxygen ions from the crystallographic cages in a single crystal of 12CaO.7Al2O3, leading to the formation of high-density (approximately 2 x 10(21) cm-3) electrons highly localized in the cages. The resulting electron forms a structure that we interpret as an F+ center and migrates throughout the crystal by hopping to a neighboring cage with conductivity approximately 100 siemens per centimeter, demonstrating that the encaged electron behaves as an anion. The electron anions couple antiferromagnetically with each other, forming a diamagnetic pair or singlet bipolaron. The resulting [Ca24Al28O64]4+(4e-) may be regarded as a thermally and chemically stable single crystalline "electride."     

Hemoglobin Freiburg: abnormal hemoglobin due to deletion of a single amino acid residue

Structural characterization of a new variant of human hemoglobin (adult), designated hemoglobin Freiburg, indicates the deletion of the valyl residue No. 23 from an otherwise normal beta-chain. The formula may be written (alpha2)beta(2)(23val-0). The abnormal hemoglobin is present with hemoglobin A in the proposita and in two of her three living children, but is not detectable in her parents. We postulate that this variant represents a triplet base deletion which most likely resulted from an unequal crossing-over between two normal betachain loci during meiosis in one of the parents of the proposita.     

A loss function to evaluate agricultural decision-making under uncertainty: a case study of soil spectroscopy

Modern sensor technologies can provide detailed information about soil variation which allows for more precise application of fertiliser to minimise environmental harm imposed by agriculture. However, growers should lose neither income nor yield from associated uncertainties of predicted nutrient concentrations and thus one must acknowledge and account for uncertainties. A framework is presented that accounts for the uncertainty and determines the cost–benefit of data on available phosphorus (P) and potassium (K) in the soil determined from sensors. For four fields, the uncertainty associated with variation in soil P and K predicted from sensors was determined. Using published fertiliser dose–yield response curves for a horticultural crop the effect of estimation errors from sensor data on expected financial losses was quantified. The expected losses from optimal precise application were compared with the losses expected from uniform fertiliser application (equivalent to little or no knowledge on soil variation). The asymmetry of the loss function meant that underestimation of P and K generally led to greater losses than the losses from overestimation. This study shows that substantial financial gains can be obtained from sensor-based precise application of P and K fertiliser, with savings of up to £121 ha^?1 for P and up to £81 ha^?1 for K, with concurrent environmental benefits due to a reduction of 4–17 kg ha^?1 applied P fertiliser when compared with uniform application.

     

Mapping water status based on aerial thermal imagery: comparison of methodologies for upscaling from a single leaf to commercial fields

Aerial thermal remote sensing can provide a means for collecting spatial plant water status data. Many studies have shown their potential in irrigation management but the adaptation of this technology is not straight forward. In this paper, knowledge accumulated in recent years on thermal imagery analysis methodology for water status mapping is summarized aiming at indicating alternatives to calculate the Crop Water Stress Index (CWSI) for commercial scale water status mapping. Based on literature overview, four forms of wet-baselines to calculate CWSI were selected, namely: artificial wet reference surface, two theoretical calculations and a statistical bio-indicator. These baselines were used to calculate CWSI based on multi-temporal aerial thermal images of cotton fields. CWSI based on a statistical bio-indicator and one of the theoretical wet-baselines provided the best correlations. It is argued though that the statistical one is preferable since it includes the plant characteristics and it is farmer-friendly. Based on bio-indicators, leaf water potential maps of three commercial fields were produced on several dates through the season. Water status spatial patterns were not static and the effect of static factors like sandy soil patches also changed through the season. The maps show the importance of in-season variability mapping for rational irrigation management. To improve current variable-rate irrigation, the concept of in-season irrigation management zones (IMZ) based on thermal-images should be considered and integrated with the delineation of static irrigation IMZ.