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Unicellular algae serve as models for the study and discovery of metabolic pathways, for the functional dissection of cell biological processes such as organellar division and cell motility, and for the identification of novel genes and gene functions. The recent completion of several algal genome sequences and expressed sequence tag collections and the establishment of nuclear and organellar transformation methods has opened the way for functional genomics approaches using algal model systems. The thermo-acidophilic unicellular red alga Galdieria sulphuraria represents a particularly interesting species for a genomics approach owing to its extraordinary metabolic versatility such as heterotrophic and mixotrophic growth on more than 50 different carbon sources and its adaptation to hot acidic environments. However, the ab initio prediction of genes required for unknown metabolic pathways from genome sequences is not trivial. A compelling strategy for gene identification is the comparison of similarly sized genomes of related organisms with different physiologies. Using this approach, candidate genes were identified that are critical to the metabolic versatility of Galdieria. Expressed sequence tags and high-throughput genomic sequence reads covering >70% of the G. sulphuraria genome were compared to the genome of the unicellular, obligate photoautotrophic red alga Cyanidioschyzon merolae. More than 30% of the Galdieria sequences did not relate to any of the Cyandioschyzon genes. A closer inspection of these sequences revealed a large number of membrane transporters and enzymes of carbohydrate metabolism that are unique to Galdieria. Based on these data, it is proposed that genes involved in the uptake of reduced carbon compounds and enzymes involved in their metabolism are crucial to the metabolic flexibility of G. sulphuraria
Polyelectrolyte multilayer assemblies containing proteins are of interest for applications such as sensors, bioreactors, and bioelectronics. A multilayer electrode was built up by the layer-by-layer strategy consisting of alternating layers of cytochrome c and poly(aniline sulfonic acid). The electrode showed a linear increase of redox active protein with the number of deposited layers. The principle of electrode preparation was transferred from needle electrodes to planar surfaces in order to further the understanding of electron transfer through the layer assembly by means of electrochemical quartz crystal microbalance studies. The deposition process was followed on-line by detection of the frequency shift of the crystals and was found to be rather fast (minutes). The total mass deposited was found to correlate well with the electrochemical response of the immobilized cyt.c. Furthermore, the influence of the polyelectrolyte was investigated by addition of PSS to the PASA solution. The strong interaction of the former polyelectrolyte seemed to hinder the electron transfer although a multilayer formation was proved. Dilution of the protein solution with redox inactive apo-cyt.c led to a strong decrease of the voltammetric signal, well beyond the percentage of apo-cyt.c inside the assembly. Thus, arguments for an electron transfer via protein-protein interaction were found
TPK1 ( formerly KCO1) is the founding member of the family of two-pore domain K 1 channels in Arabidopsis ( Arabidopsis thaliana), which originally was described following expression in Sf9 insect cells as a Ca2(+)- and voltage- dependent outwardly rectifying plasma membrane K 1 channel. In plants, this channel has been shown by green fluorescent protein fusion to localize to the vacuolar membrane, which led to speculations that the TPK1 gene product would be a component of the nonselective, Ca2+ and voltage- dependent slow-vacuolar (SV) cation channel found in many plants species. Using yeast ( Saccharomyces cerevisiae) as an expression system for TPK1, we show functional expression of the channel in the vacuolar membrane. In isolated vacuoles of yeast yvc1 disruption mutants, the TPK1 gene product shows ion channel activity with some characteristics very similar to the SV-type channel. The open channel conductance of TPK1 in symmetrically 100mM KCl is slightly asymmetric with roughly 40 pS at positive membrane voltages and 75 pS at negative voltages. Similar to the SV-type channel, TPK1 is activated by cytosolic Ca2+, requiring micromolar concentration for activation. However, in contrast to the SV- type channel, TPK1 exhibits strong selectivity for K+ over Na+, and its activity turned out to be independent of the membrane voltage over the range of +/- 80mV. Our data clearly demonstrate that TPK1 is a voltage- independent, Ca2+- activated, K+- selective ion channel in the vacuolar membrane that does not mediate SV- type ionic currents
In this paper, habitat models were used to predict potential habitat for endangered species, which is an important question in landscape and conservation planning. Based on logistic regression, we developed habitat distribution models for the burnet moth Zygaena carniolica and the nymphalid butterfly Coenonympha arcania in Northern Bavaria, Germany. The relation between adult occurrence and habitat parameters, including the influence of landscape context, was analyzed on, 118 sites. Habitat connectivity analyses were carried out on the basis of (1) habitat suitability maps generated from these models and (2) dispersal data from mark recapture studies. Our results showed that (1) the presence of the burnet depended mainly on the presence of nectar plants and of nutrient-poor dry grasslands in direct vicinity, that of the nymphalid on larger areas of extensively used dry grasslands within 100 m vicinity in combination with small patches of higher shrubs and bushes. (2) Internal as well as external validation indicated the robustness and general applicability of the models. Transferability in time and space indicated their high potential relevance for applications in nature conservation, such as predicting possible effects of land use changes. (3) Habitat connectivity analyses revealed a high degree of habitat connectivity within the study area. Thus, we could show no effects of isolation or habitat size for both species. (c) 2005 Elsevier Ltd. All rights reserved
Cytochrome P450 (CYP) is a large family of enzymes containing heme as the active site. Since their discovery and the elucidation of their structure, they have attracted the interest of scientist for many years, particularly due to their catalytic abilities. Since the late 1970s attempts have concentrated on the construction and development of electrochemical sensors. Although sensors based on mediated electron transfer have also been constructed, the direct electron transfer approach has attracted most of the interest. This has enabled the investigation of the electrochemical properties of the various isoforms of CYP. Furthermore, CYP utilized to construct biosensors for the determination of substrates important in environmental monitoring, pharmaceutical industry and clinical practice. (c) 2004 Elsevier B. V. All rights reserved
Molecular characterization of the ebony gene from the American cockroach, Periplaneta americana
(2005)
Biogenic amines are an important class of primary messengers in the central (CNS) and peripheral nervous systems and in peripheral organs. These substances regulate and modulate many physiological and behavioral processes. Various inactivation mechanisms for these substances exist to terminate biogenic amine-mediated signal transduction. In vertebrates, the enzymes monoamine oxidase and/or catechol-O-methyl-transferase are involved in these processes. In insects, however, in which both enzymes are low in abundance or absent, biogenic amines are inactivated mainly by N- acetylation or O-sulphation. In Droso-philo, beta-alanyl conjugation mediated by the Ebony protein has recently been shown to be a novel and alternative pathway for biogenic amine inactivation. Here, we report the cloning of ebony cDNA (Peaebony) from a brain-specific cDNA library of the cockroach Periplaneta americana. The open reading frame encodes a protein of 860 amino acid residues (PeaEbony). The PeaEbony polypeptide shares homology to Ebony sequences from Anopheles gambiae, Apis mellifera, and Drosophila melonogaster. In addition, PeaEbony exhibits sequence similarity to a family of microbial non-ribosomal peptide synthetases. The mRNA encoding PeaEbony is highly expressed in the cockroach brain and to a lesser extent in the salivary glands. PeaEbony is, therefore, probably involved in the inactivation of various biogenic amines through beta-alanyl conjugation in the cockroach CNS. Since the salivary glands in Periplaneta are innervated by dopaminergic and serotonergic neurons, PeaEbony probably also biochemically modifies dopamine and serotonin in these acinar glands. Arch. Insect Biochem. (c) 2005 Wiley-Liss, Inc