Proteomic analysis of Pteris vittata fronds: two arbuscular mycorrhizal fungi differentially modulate protein expression under arsenic contamination

Arbuscular mycorrhizae (AM) are the most widespread mutualistic symbioses between the roots of most land plants and a phylum of soil fungi. AM are known to influence plant performance by improving mineral nutrition, protecting against pathogens and enhancing resistance or tolerance to biotic and abiotic stresses. The aim of this study was to investigate the frond proteome of the arsenic hyperaccumulator fern Pteris vittata in plants that had been inoculated with one of the two AM fungi (Glomus mosseae or Gigaspora margarita) with and without arsenic treatment. A protective role for AM fungi colonisation in the absence of arsenic was indicated by the down-regulation of oxidative damage-related proteins. Arsenic treatment of mycorrhizal ferns induced the differential expression of 130 leaf proteins with specific responses in G. mosseae- and Gi. margarita-colonised plants. Up-regulation of multiple forms of glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and enolase, primarily in G. mosseae-inoculated plants, suggests a central role for glycolytic enzymes in arsenic metabolism. Moreover, a putative arsenic transporter, PgPOR29, has been identified as an up-regulated protein by arsenic treatment.     

光照强度、温度、pH、盐度对小球藻（Chlorella）光合作用的影响

利用测定净光合放氧速率的方法研究了光照强度、温度、pH、盐度对小球藻（Chlorella sp.XQ-200419）和海洋小球藻（Chlorella marina NJ-016）光合作用的影响。小球藻（Chlorella sp.XQ-200419）的适宜光照强度范围为100～〉1600μmo·lm-2·s-1,光饱和点在500μmo·lm-2·s-1附近;适宜温度范围为25～42.5℃,最适温度为37.5℃;适宜pH值范围为6.5～9.0,最适pH值为7.0;对盐度的适应范围较广,在0～0.6mol/L范围内,随着盐度的升高,净光合放氧速率有下降趋势。海洋小球藻（Chlorella marina NJ-016）的适宜光照强度范围为400～〉1600μmol·m-2·s-1,光饱和点在1400μmo·lm-2.s-1附近;适宜温度范围为25～42.5℃,最适温度为37.5℃;适宜pH值范围为5.0～9.0,最适pH值为8.0;对盐度有很好的适应性,在0～0.6mol/L范围内,随着盐度升高,净光合放氧速率明显上升。小球藻和海洋小球藻的净光合放氧速率随光照强度、温度、pH值和盐度变化的规律,表明了两种小球藻的基本生理生态学特性：能适应较强的光照强度、较高的温度、中性偏碱的环境和较高的盐度。研究结果有助于小球藻培养条件的优化。两种小球藻对光照强度、温度、pH值和盐度变化的反应也有所不同：与小球藻（Chlorella sp.XQ-200419）相比,海洋小球藻（Chlorella marina NJ-016）对光照强度有更好的适应性,对pH值变化有更宽的适应范围,适当提高盐度对其光合作用有明显的促进作用。这表明海洋小球藻（Chlorella marina NJ-016）在快速生长繁殖方面具有更大的潜力,这一研究结果为筛选适合于大量培养的优良藻种提供了依据。     

The development of stimulus‐specific auditory responses requires song exposure in male but not female zebra finches

Juvenile male zebra finches develop their song by imitation. Females do not sing but are attracted to males' songs. With functional magnetic resonance imaging and event‐related potentials we tested how early auditory experience shapes responses in the auditory forebrain of the adult bird. Adult male birds kept in isolation over the sensitive period for song learning showed no consistency in auditory responses to conspecific songs, calls, and syllables. Thirty seconds of song playback each day over development, which is sufficient to induce song imitation, was also sufficient to shape stimulus‐specific responses. Strikingly, adult females kept in isolation over development showed responses similar to those of males that were exposed to songs. We suggest that early auditory experience with songs may be required to tune perception toward conspecific songs in males, whereas in females song selectivity develops even without prior exposure to song. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2010     

Proteomic pattern-based analyses of light responses in Arabidopsis thaliana wild-type and photoreceptor mutants

Light critically affects the physiology of plants. Using two-dimensional gel electrophoresis, we used a proteomics approach to analyze the responses of Arabidopsis thaliana to red (660 nm), far-red (730 nm) and blue (450 nm) light, which are utilized by type II and type I phytochromes, and blue light receptors, respectively. Under specific light treatments, the proteomic profiles of 49 protein spots exhibited over 1.8-fold difference in protein abundance, significant at p <0.05. Most of these proteins were metabolic enzymes, indicating metabolic changes induced by light of specific wavelengths. The differentially-expressed proteins formed seven clusters, reflecting co-regulation. We used the 49 differentially-regulated proteins as molecular markers for plant responses to light, and by developing a procedure that calculates the Pearson correlation distance of cluster-to-cluster similarity in expression changes, we assessed the proteome-based relatedness of light responses for wild-type and phytochrome mutant plants. Overall, this assessment was consistent with the known physiological responses of plants to light. However, we also observed a number of novel responses at the proteomic level, which were not predicted from known physiological changes.     

Prediction of crop response by linearisation about control approximation

A new method for modelling genotype x environment interaction: APLAT. The yield predicted by a crop-simulation model is developed as a Taylor series in the neighbourhood of a parameter vector of a control genotype. With this local linearisation, these genotype parameters can be estimated by a linear regression of the observed yield on the derivatives of the crop-simulation model predictions with respect to its parameters.     

Motile behaviour of the bloom-forming ciliate Mesodinium rubrum

Mesodinium rubrum (Lohman) (=Myrionecta rubra Jankowsky) swims backwards in jumps of short duration interspersed by longer periods of rest. Cells attain a velocity of up to 1.2 cm s^-1 during jumps and this is probably a speed record for ciliates. The ciliate carries long cirri that serve as mechanoreceptors and for orientating the cell at the initiation of jumps, while the ciliary rows on the posterior part of the cell are responsible for propulsion. The cirri are sensitive to shear so that they can orientate themselves against the current in a siphon flow (such as generated by filter-feeding copepods). Mesodinium cells do not reorientate their body axis during sinking, but they reorientate their direction during the initiation of jumps so that they always tend to move upwards. Because the cells sink between jumps they can regulate their vertical position by modulation of the frequency of jumps. The cells' tendency to drift vertically up or down is light dependent. The jumps are so rapid that these phototrophic organisms can enhance their uptake of dissolved mineral nutrients beyond the limitation of molecular diffusion.     

Sensing the Heat of Tomato Products Red: The New Approach to the Objective Assessment of their Color

The concept of optothermal window (OW) detection was used for the first time to assess the color of several products (juice, purée, paste) derived from thermally processed tomatoes. Unlike traditional techniques that operate either in the reflectance or transmission mode, the method proposed here actually relies on indirect measurement of absorbance in optically opaque and scattering samples. Very good correlation between the magnitude of the OW signal and the color-related parameters [colorimetric index L* and tomato paste index (TPI)] was observed.     

Holocene Carbon Accumulation of Fen Peatlands in Boreal Western Canada: A Complex Ecosystem Response to Climate Variation and Disturbance

Understanding the long-term ecological dynamics of northern peatlands is essential for assessment of the possible responses and feedbacks of these carbon-rich ecosystems to climate change and natural disturbance. I used high-resolution macrofossil and lithological analyses of a fen peatland in western Canada to infer the Holocene developmental history of the peatland, to document the temporal pattern of long-term peat accumulation, and to investigate ecosystems responses to climate changes in terms of species composition and carbon accumulation. The peatland has been dominated by sedges and brown mosses during its 10,000-year history, despite interruption by tephra deposition. Peat accumulation rates vary by more than an order of magnitude and decline from 5500 to 1300 cal BP, resulting in a convex depth–age curve, which contrasts with the carbon accumulation patterns documented for oceanic peatlands. The synthesis of regional data from continental western Canada indicates that fens tend to accumulate more carbon than bogs of the same ages. These data suggest that the carbon sink potential of northern peatlands has varied dramatically in the past, so estimates of the present and projected carbon sink strengths of these peatlands need to take this temporal variation into consideration. Widespread slowdown of peat accumulation over the last 4000 years may have resulted from climate cooling in northern latitudes after the Holocene insolation maximum. The findings indicate that long-term peatland dynamics are modified by many local and regional factors and that gradual environmental change may be capable of triggering abrupt shifts and jumps in ecosystem states.     

Intracellular cytokine staining for the characterization and quantitation of antigen-specific T lymphocyte responses

Standard proliferation assays used for analysis of T cell function have significant shortcomings, including limited sensitivity, lack of quantitative readouts, and considerable variability. Recently, flow cytometric methods have been developed to allow multiparametric detection of cell surface antigens and intracellular cytokine expression in response to polyclonal stimuli and antigen. We have optimized an intracellular cytokine staining assay in the non-human primate model of AIDS, which allows us to identify antigen-specific T lymphocytes at the single cell level with high sensitivity, while reducing background staining to a minimum. Central to our optimized protocol is the addition of cross-linked costimulatory anti-CD28 and anti-CD49d Mabs, a modification that results in up to 3-fold enhancement of the frequency of cytokine-secreting CD4(+) T cells following superantigen or antigen-specific stimulation. Optimization of the antigen concentration and duration of antigenic stimulation resulted in a convenient and highly reproducible assay, which permits delineation of antigen-specific cells at the single cell level, thereby providing new insights into pathogen-specific immune responses and allowing detailed phenotypic analysis of extremely low frequency events.