Biosynthesis of landomycin E deoxysugar part in Streptomyces globisporus 1912: sequencing and analysis of lndZ1 and lndZ3 genes

DNA fragment of landomycin E biosynthesis gene cluster 1.5 kb in size has been completely sequenced and two open reading frames were identified. Gene lndZ1 resembles NDP-hexose-3,5-epimerase and lndZ3 is similar to NDP-hexose-4-ketoreductases. LndZ1 and LndZ3 proteins are suggested to accomplish two last catalytic steps towards deoxysugar L-rhodinose present in landomycin E carbohydrate moietyThis work was supported by grant BG-117b from Ministry of Education and Science of Ukraine (to V.F). We are gratefull to the staff of DNA sequencing facility at the Dept. of Biochemistry of Cambridge University (John Lester, Tania Mironenko, Nataliya Scott) for help in sequencing

An algorithmic method for functionally defining regions of interest in the ventral visual pathway

In a widely used functional magnetic resonance imaging (fMRI) data analysis method, functional regions of interest (fROIs) are handpicked in each participant using macroanatomic landmarks as guides, and the response of these regions to new conditions is then measured. A key limitation of this standard handpicked fROI method is the subjectivity of decisions about which clusters of activated voxels should be treated as the particular fROI in question in each subject. Here we apply the Group-Constrained Subject-Specific (GSS) method for defining fROIs, recently developed for identifying language fROIs (Fedorenko et al., 2010), to algorithmically identify fourteen well-studied category-selective regions of the ventral visual pathway (Kanwisher, 2010). We show that this method retains the benefit of defining fROIs in individual subjects without the subjectivity inherent in the traditional handpicked fROI approach. The tools necessary for using this method are available on our website (http://web.mit.edu/bcs/nklab/GSS.shtml).Ellison Medical Foundatio

SEQUENCING AND ANALYSIS OF PUTATIVE 3D-4H RING CYCLASE GENE lndF OF STREPTOMYCES GLOBISPORUS 1912 LANDOMYCIN E BIOSYNTHETIC GENE CLUSTER

DNA fragment of landomycin E biosynthesis gene cluster 700 bp in size has been completely sequenced. 3?-end of lndE (oxygenase) was identified, 5?-end of lndA (ketosynthase) and entire ORF for previously not sequenced lanF homologue, lndF. Analysis of lndF putative translation product revealed that it is highly conservative in comparison with other known cyclases from antibiotic biosynthesis gene clusters. Unlike urdamycin, jadomycin biosynthetic clusters, lndF and lndA are uncoupled, as well as genes lanF and lanA. Genes lndF and lndA are not preceded by direct or inverted repeats, putative sites for binding of transcriptional activator LndI. In contrast, lanF is flanked at it's 5?-end by three direct repeats, possible target for regulatory protein LanI.L. Castro is acknowledged for help in sequencing. This work was supported by INTAS grant YSF 00-208 to B.O

Scaling of loop-erased walks in 2 to 4 dimensions

We simulate loop-erased random walks on simple (hyper-)cubic lattices of dimensions 2,3, and 4. These simulations were mainly motivated to test recent two loop renormalization group predictions for logarithmic corrections in $d=4$, simulations in lower dimensions were done for completeness and in order to test the algorithm. In $d=2$, we verify with high precision the prediction $D=5/4$, where the number of steps $n$ after erasure scales with the number $N$ of steps before erasure as $n\sim N^{D/2}$. In $d=3$ we again find a power law, but with an exponent different from the one found in the most precise previous simulations: $D = 1.6236\pm 0.0004$. Finally, we see clear deviations from the naive scaling $n\sim N$ in $d=4$. While they agree only qualitatively with the leading logarithmic corrections predicted by several authors, their agreement with the two-loop prediction is nearly perfect.Comment: 3 pages, including 3 figure

The role of initial conditions in the ageing of the long-range spherical model

The kinetics of the long-range spherical model evolving from various initial states is studied. In particular, the large-time auto-correlation and -response functions are obtained, for classes of long-range correlated initial states, and for magnetized initial states. The ageing exponents can depend on certain qualitative features of initial states. We explicitly find the conditions for the system to cross over from ageing classes that depend on initial conditions to those that do not.Comment: 15 pages; corrected some typo

Heterologous cross-expression of oxygenase and glycosyltransferase genes in streptomycetes, producing angucyclic antibiotics

The heterologous expression of oxygenase genes urdM, ovmOIII, lanM2, lndZ5 and glycosyltransferase gene urdGT2 in different angucycline producers of genus Streptomyces has been carried out. The introduction of genes urdM, lanM2 and urdGT2 results in the accumulation of new glycosylated compounds in several strains under investigation. A number of processed recombinant strains display streptomycin sensitivity and decrease in total antibacterial activity. The obtained data is an evidence of changes in antibiotics production, resulting from post polyketide synthase (postPKS) tailoring gene expression across streptomycete strains. Our study demonstrates the potential of post PKS tailoring genes for generation of novel bioactive metabolites.Здійснено гетерологічну експресію генів оксигеназ urdM, ovmOIII, lanM2, lndZ5 та глікозилтрансферази urdGT2 у різних видів продуцентів ангуциклінів з роду Streptomyces. Введення генів urdM, lanM2 та urdGT2 у деякі з досліджуваних штамів зумовлює накопичення ними нових глікозильованих сполук. Виявлено виникнення чутливості до стрептоміцину та різке зниження загальної антибактерійної активності у деяких із одержаних рекомбінантних штамів. Отримані дані є свідченням модифікації продукції антибіотиків, яка є наслідком експресії генів постполікетидного синтезу (пост-ПКС) у штамах стрептоміцетів. Наші дослідження демонструють потенціал генів пост-ПКС у створенні нових біологічно активних метаболітів.Проведена гетерологическая экспрессия генов оксигеназ urdM, ovmOIII, lanM2, lndZ5 и гликозилтрансферазы urdGT2 в разных видах продуцентов ангуциклинов из рода Streptomyces. Введение генов urdM, lanM2 и urdGT2 в некоторые из исследуемых штаммов обусловливает накопление ими новых гликозилированных соединений. Обнаружено появление чувствительности к стрептомицину и резкое снижение общей антибактериальной активности у некоторых из полученных рекомбинантных штаммов. Представленные данные свидетельствуют о модификации продукции антибиотиков, которая является следствием экспрессии генов пост-поликетидного синтеза (пост-ПКС) в штаммах стрептомицетов. Наши исследования демонстрируют потенциал генов пост-ПКС в создании новых биологически активных метаболитов

Electrical properties of Bi-implanted amorphous chalcogenide films

The impact of Bi implantation on the conductivity and the thermopower of amorphous chalcogenide films is investigated. Incorporation of Bi in Ge-Sb-Te and GeTe results in enhanced conductivity. The negative Seebeck coefficient confirms onset of the electron conductivity in GeTe implanted with Bi at a dose of 2x1016 cm-2. The enhanced conductivity is accompanied by defect accumulation in the films upon implantation as is inferred by using analysis of the space-charge limited current. The results indicate that native coordination defects in lone-pair semiconductors can be deactivated by means of ion implantation, and higher conductivity of the films stems from additional electrically active defects created by implantation of bismuth.Comment: This is an extended version of the results presented in Proc. SPIE 8982, 898213 (2014

Field theory conjecture for loop-erased random walks

We give evidence that the functional renormalization group (FRG), developed to study disordered systems, may provide a field theoretic description for the loop-erased random walk (LERW), allowing to compute its fractal dimension in a systematic expansion in epsilon=4-d. Up to two loop, the FRG agrees with rigorous bounds, correctly reproduces the leading logarithmic corrections at the upper critical dimension d=4, and compares well with numerical studies. We obtain the universal subleading logarithmic correction in d=4, which can be used as a further test of the conjecture.Comment: 5 page

Critical Behaviour of 3D Systems with Long-Range Correlated Quenched Defects

A field-theoretic description of the critical behaviour of systems with quenched defects obeying a power law correlations $\sim |{\bf x}|^{-a}$ for large separations ${\bf x}$ is given. Directly for three-dimensional systems and different values of correlation parameter $2\leq a \leq 3$ a renormalization analysis of scaling function in the two-loop approximation is carried out, and the fixed points corresponding to stability of the various types of critical behaviour are identified. The obtained results essentially differ from results evaluated by double $\epsilon, \delta$ - expansion. The critical exponents in the two-loop approximation are calculated with the use of the Pade-Borel summation technique.Comment: Submitted to J. Phys. A, Letter to Editor 9 pages, 4 figure