Weak field influence on biomolecular changes

Model equations for the kinetics of the synthesis and decay of molecular aggregates are used to show the high sensitivity of equilibrium concentrations of high-molecular aggregates to external radiation. This phenomenon is used to explain the effects of low-intensity microwave fields on the functioning of biological systems. The experimental results on the influence of SHF-radiation on ferricyanide reduction by erythrocytes are interpreted in detail.     

A partial-complementary adapter for an improved and simplified ligation-mediated suppression PCR technique

Ligation-mediated suppression PCR (LMS-PCR) is a powerful tool for walking in unknown genomic DNA regions from known adjacent sequences. This approach has made it feasible to obtain promoter sequences and to enable researchers to identify full-length gene sequences or isoforms of multigene families. However, the advantages of LMS-PCR can be obviated by the presence of incomplete base modifications on the suppression adapters. We propose here that a 'partial-complementary adapter' is a more reliable suppression adapter, demanding only 5'-end phosphorylation. We also describe a simplified procedure for the easier preparation of PCR templates with very small quantities of DNA and a fast and direct characterization of the suppression-PCR products. A set of practical guidelines is proposed for pre-checking the efficiency of the adapter modification using two model systems: bacteriophage lambda (lambda) and Arabidopsis.     

Functional,Morphological, and Evolutionary Characterization of Hearing in Subterranean,Eusocial African Mole-Rats

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Signal amplification in biological and electrical engineering systems: Universal role of cascades

In this paper we compare the cascade mechanisms of signal amplification in biological and electrical engineering systems, and show that they share the capacity to considerably amplify signals, and respond to signal changes both quickly and completely, which effectively preserves the form of the input signal. For biological systems, these characteristics are crucial for efficient and reliable cellular signaling. We show that this highly-efficient biological mechanism of signal amplification that has naturally evolved is mathematically fully equivalent with some man-developed amplifiers, which indicates parallels between biological evolution and successful technology development.     

Performance of a time-resolved IR facility for assessment of protonation states and polarity changes in carboxyl groups in a large membrane protein,mammalian cytochrome c oxidase,under turnover conditions in a sub-millisecond time resolution

Time-resolved IR analyses for the protonation and polarity changes of carboxyl groups involved in proton pump enzymes under turnover conditions are indispensable for elucidation of their proton-pump mechanisms. We have developed a new time-resolved infrared facility by introducing a flow system for transferring highly concentrated and thus viscous protein solution to a thin (50?μm) flow cell equipped in a highly sensitive IR spectrometer constructed with the femtosecond mid-IR pulse laser with spectral width of 350?cm^?1 as an IR white light source equipped with multi-channel MCT detector. This facility equipped with O₂ supply system enables the sub-millisecond time scale infrared measurements of the O₂ reduction coupled with proton pumping by bovine cytochrome c oxidase (CcO) initiated by CO-flash photolysis in the COOH (1725–1770?cm^?1) region with the accuracy of about 10?μO.D. under the background O.D. of 1. The facility identifies a band intensity change at ~1744?cm^?1 assignable to protonation of a carboxyl group coupled with a single electron transfer to the O₂ reduction center within 1?ms after initiation of the reaction. The results suggest that the facility detects protonation of a single carboxyl group included in large proteins like as CcO (210?kDa). The present facility sensitively identifies also polarity changes in COOH group by detecting shifts of the bands near 1750?cm^?1 and 1760?cm^?1, without significant intensity changes. These findings show the performance of this facility sufficiently high for providing crucial information for understanding the proton transferring mechanisms of protein carboxyl groups.     

Light-harvesting chlorophyll protein (LHCII) drives electron transfer in semiconductor nanocrystals

Type-II quantum dots (QDs) are capable of light-driven charge separation between their core and the shell structures; however, their light absorption is limited in the longer-wavelength range. Biological light-harvesting complex II (LHCII) efficiently absorbs in the blue and red spectral domains. Therefore, hybrid complexes of these two structures may be promising candidates for photovoltaic applications. Previous measurements had shown that LHCII bound to QD can transfer its excitation energy to the latter, as indicated by the fluorescence emissions of LHCII and QD being quenched and sensitized, respectively. In the presence of methyl viologen (MV), both fluorescence emissions are quenched, indicating an additional electron transfer process from QDs to MV. Transient absorption spectroscopy confirmed this notion and showed that electron transfer from QDs to MV is much faster than fluorescence energy transfer between LHCII and QD. The action spectrum of MV reduction by LHCII-QD complexes reflected the LHCII absorption spectrum, showing that light absorbed by LHCII and transferred to QDs increased the efficiency of MV reduction by QDs. Under continuous illumination, at least 28 turnovers were observed for the MV reduction. Presumably, the holes in QD cores were filled by a reducing agent in the reaction solution or by the dihydrolipoic-acid coating of the QDs. The LHCII-QD construct can be viewed as a simple model of a photosystem with the QD component acting as reaction center.     

Selecting a Hiding Place: Anuran Diversity and the use of Bromeliads in a Threatened Coastal Sand Dune Habitat in Brazil

Among vertebrates, anuran amphibians represent the highest number of species associated with bromeliads and possess a range of ecological, behavioral, and morphological specializations to life in these plants. Despite the importance of bromeliads as biodiversity amplifiers, and their diversity in some habitats, studies of the relationship between anurans and these plants are scarce in Brazil. Here, we investigated the way anurans select and use bromeliads in a threatened coastal habitat. We analyzed data from 23 standardized samples of the anurans associated with the bromeliad Neoregelia cruenta in the Restinga de Maricá, State of Rio de Janeiro, Southeastern Brazil. We found nine anuran species using these bromeliads, representing the highest richness reported for a Brazilian restinga. We identified a general pattern of bromeliad usage, where plants located at the edges of scrub patches (exposed to the sun) were more frequently occupied by anurans than those located more to the center (in the shade). There is strong evidence of an active selective process based on the quality of the water stored in the rosette, which differs between plants depending on their position in the scrub patch. Although the number of individuals varied during the period of study, the frequency of bromeliads used was constant, indicating that plant occupation follows a regular pattern throughout the year. Furthermore, the high frequency of bromeliads used by anurans during the whole year highlights the importance of considering these plants in developing conservation programs concerning the protection of anurans.     

光耦功率放大技术在CT超低剂量扫描的研究

目的将全新的光电耦合高电压强电流放大处理技术用于CT机的前置放大处理中,隔离噪声和高电压大电流放大图像信号,实现超低剂量扫描,高清晰成像。方法将光电耦合放大器制作成射线剂量仪,并用CT机等超低剂量120KV、3-6mA…对其曝光,并与标准射线剂量仪校准,使其输出值不仅为射线剂量值,更能显示为高电压和大电流的优质图像信噪比。结果超小电流扫描经探测和光耦放大后最大值为87.5V和0.96A,而噪声电压为0.13μV、电流仅为0.02μA,给超低剂量扫描和传输处理时的功耗及高电压的宽动态范围显示留了很大空间。结论 CT超低剂量扫描时光耦放大器可在源头彻底隔离各种噪声并超高倍放大、高电压大电流输出图像信号,可保证高清晰高分辨率成像。     

Individual colour patches as multicomponent signals

Colour patches are complex traits, the components of which may evolve independently through a variety of mechanisms. Although usually treated as simple, two-dimensional characters and classified as either structural or pigmentary, in reality colour patches are complicated, three-dimensional structures that often contain multiple pigment types and structural features. The basic dermal chromatophore unit of fishes, reptiles and amphibians consists of three contiguous cell layers. Xanthophores and erythrophores in the outermost layer contain carotenoid and pteridine pigments that absorb short-wave light; iridophores in the middle layer contain crystalline platelets that reflect light back through the xanthophores; and melanophores in the basal layer contain melanins that absorb light across the spectrum. Changes in any one component of a chromatophore unit can drastically alter the reflectance spectrum produced, and for any given adaptive outcome (e.g. an increase in visibility), there may be multiple biochemical or cellular routes that evolution could take, allowing for divergent responses by different populations or species to similar selection regimes. All of the mechanisms of signal evolution that previously have been applied to single ornaments (including whole colour patches) could potentially be applied to the individual components of colour patches. To reach a complete understanding of colour patch evolution, however, it may be necessary to take an explicitly multi-trait approach. Here, we review multiple trait evolution theory and the basic mechanisms of colour production in fishes, reptiles and amphibians, and use a combination of computer simulations and empirical examples to show how multiple trait evolution theory can be applied to the components of single colour patches. This integrative perspective on animal colouration opens up a host of new questions and hypotheses. We offer specific, testable functional hypotheses for the most common pigmentary (carotenoid, pteridine and melanin) and structural components of vertebrate colour patches.