Prolonged sensitivity of immobilized thylakoid membranes in cross-linked matrix to atrazine

Freshly prepared pea thylakoid membranes were immobilized in bovine serum albumin-glutaraldehyde cross-linked matrix (BSA-GA matrix) and their stability under long term storage was analyzed by Pulse-Amplitude-Modulated (PAM) chlorophyll fluorescence and photosynthetic oxygen evolution measured by oxygen rate electrode. The thylakoid membranes stored at 4 °C showed prolonged stability in BSA-GA matrix and additional adsorption on nitrocellulose membrane filters gave them more stability. The sensitivity of the parameters of the oxygen evolution of thylakoid membranes to atrazine increased with immobilization. The half-inhibition time for oxygen evolution and quantum efficiency of photosynthesis could be prolonged to more than 15 days. These results suggest that the immobilized thylakoid membranes in BSA-GA matrix can be used as biological receptor in biosensors for a long period of time (up to 25 days) applying the proposed new method for atrazine detection by using polarographic oxygen rate electrode. This method is more sensitive, faster and easier to use than other methods for detection of herbicides based on determination of the photochemical activity of photosystem II.     

Rapid Hormetic Responses of Photosystem II Photochemistry of Clary Sage to Cadmium Exposure

Five-day exposure of clary sage (Salvia sclarea L.) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (Φ_PSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (Φ_NO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (¹O₂) formation. A basal ROS level was detected in control plant leaves for optimal growth, while a low increased level of ROS under 5 days Cd exposure seemed to be beneficial for triggering defense responses, and a high level of ROS out of the boundaries (8 days Cd exposure), was harmful to plants. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered. However, exposure to a combination of Cd and high light or to Cd alone (8 days) resulted in an inhibition of PSII functionality, indicating Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposure and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively.     

An analysis of hydrogen production from renewable electricity sources

Three aspects of producing hydrogen via renewable electricity sources are analyzed to determine the potential for solar and wind hydrogen production pathways: a renewable hydrogen resource assessment, a cost analysis of hydrogen production via electrolysis, and the annual energy requirements of producing hydrogen for refueling. The results indicate that ample resources exist to produce transportation fuel from wind and solar power. However, hydrogen prices are highly dependent on electricity prices. For renewables to produce hydrogen at $2 kg⁻¹, using electrolyzers available in 2004, electricity prices would have to be less than $0.01 kWh⁻¹. Additionally, energy requirements for hydrogen refueling stations are in excess of 20 GWh/year. It may be challenging for dedicated renewable systems at the filling station to meet such requirements. Therefore, while plentiful resources exist to provide clean electricity for the production of hydrogen for transportation fuel, challenges remain to identify optimum economic and technical configurations to provide renewable energy to distributed hydrogen refueling stations.     

Neurturin and GDNF promote proliferation and survival of enteric neuron and glial progenitors in vitro

Signaling through the c-Ret tyrosine kinase and the endothelin B receptor pathways is known to be critical for development of the enteric nervous system. To clarify the role of these receptors in enteric nervous system development, the effect of ligands for these receptors was examined on rat enteric neuron precursors in fully defined medium in primary culture. In this culture system, dividing Ret-positive cells differentiate, cluster into ganglia containing neurons and enteric glia, and create extensive networks reminiscent of the enteric plexus established in vivo. Glial cell-line-derived neurotrophic factor (GDNF) and neurturin both potently support survival and proliferation of enteric neuron precursors in this system. Addition of either neurturin or GDNF to these cultures increased the number of both neurons and enteric glia. Persephin, a third GDNF family member, shares many properties with neurturin and GDNF in the central nervous system and in kidney development. By contrast, persephin does not promote enteric neuron precursor proliferation or survival in these cultures. Endothelin-3 also does not increase the number of enteric neurons or glia in these cultures.     

Unimpaired macrophage differentiation and activation in mice lacking the zinc finger transplantation factor NGFI-A (EGR1)

The zinc finger protein NGFI-A (also called EGR1, Krox24, or zif268) is a candidate regulator of myeloid cell differentiation. Evidence supporting this hypothesis is twofold. First, NGFI-A antisense oligonucleotides prevent macrophage differentiation in HL-60 and U937 myeloid leukemia cell lines and in normal bone marrow cells. Second, enforced expression of NGFI-A blocks granulocytic differentiation and promotes macrophage differentiation in HL-60 cells and in the hematopoietic progenitor cell line 32D. We sought to determine the effect of NGFI-A deficiency on macrophage differentiation and function in vivo by examining native bone marrow cells from mice homozygous for a disrupted allele of NGFI-A derived from gene-targeted ES cells. Macrophages were observed in peripheral blood and several tissues, indicating that NGFI-A was not required for the formation of a variety of macrophage compartments. No differences in myeloid cell differentiation were observed between wild-type and NGFI-A-/- bone marrow cells cultured in the presence of macrophage, granulocyte-macrophage, or granulocyte colony-stimulating factor (M-CSF, GM-CSF, or G-CSF). Activation of NGFI-A-/- macrophages was comparable to that of wild-type macrophages as determined by nitric oxide production and increased cell surface expression of class II major histocompatibility complex molecules. Moreover, NGFI-A-/- mice showed no increased mortality or bacteria] burden when challenged with Listeria monocytogenes. Together, these results indicate that NGFI-A is not required for macrophage differentiation or activation.     

Special Issue on Deep Learning for Robotic Vision

International Journal of Computer Vision -     

Liquid Chromatography Orbitrap Mass Spectrometry Method for Analysis of Homocysteine and Related Aminothiols in Cereal Products

Liquid chromatography Orbitrap mass spectrometry method for quantification of biological aminothiols (cysteine, homocysteine, and glutathione) in cereal products has been developed. The assay is based on preliminary derivatization with N-(2-acridonyl)maleimide and high resolution accurate mass spectrometry with utilization of dl-Homocystine-3,3,3′,3′,4,4,4′,4′-d₈ (homocystine-d₈) as internal standard. The limits of quantification for homocysteine, cysteine, and glutathione are 19.44, 40.78, and 338.93 pg, respectively, per 10 μl injection. Intra- and inter-day precision expressed as relative standard deviations are in the range of 1.76 to 2.94 % and 1.06 to 4.13 %, respectively. The average recoveries were 98 % for Hcy, 87 % for Cys, and 92 % for GSH. Wheat, maize, and bakery products with different origin were analyzed. The content of Hcy in the investigated samples was found to be in range of 9–436 μg/100 g, Cys in range of 29–6,895 μg/100 g and GSH in range of 259–14,795 μg/100 g.