Showing papers by "Tallinn University of Technology published in 2006"
TL;DR: RT-PCR results showed that the expression levels of many tapetum-preferential genes are reduced significantly in the dyt1 mutant, indicating that DYT1 is important for the expression of tapetal genes.
Abstract: In flowering plants, male fertility depends on proper cell differentiation in the anther. However, relatively little is known about the genes that regulate anther cell differentiation and function. Here, we report the analysis of a new Arabidopsis male sterile mutant, dysfunctional tapetum1 (dyt1). The dyt1 mutant exhibits abnormal anther morphology beginning at anther stage 4, with tapetal cells that have excess and/or enlarged vacuoles and lack the densely stained cytoplasm typical of normal tapetal cells. The mutant meiocytes are able to complete meiosis I, but they do not have a thick callose wall; they often fail to complete meiotic cytokinesis and eventually collapse. DYT1 encodes a putative bHLH transcription factor and is strongly expressed in the tapetum from late anther stage 5 to early stage 6, and at a lower level in meiocytes. In addition, the level of DYT1 mRNA is reduced in the sporocyteless/nozzle (spl/nzz) and excess microsporocytes1/extra sporogenous cell (ems1/exs) mutants; together with the mutant phenotypes, this suggests that DYT1 acts downstream of SPL/NZZ and EMS1/EXS. RT-PCR results showed that the expression levels of many tapetum-preferential genes are reduced significantly in the dyt1 mutant, indicating that DYT1 is important for the expression of tapetum genes. Our results support the hypothesis that DYT1 is a crucial component of a genetic network that controls anther development and function.
380 citations
TL;DR: The age of initial deglaciation indicates that the SIS may have contributed to an abrupt rise in global sea level and subsequent ice-margin fluctuations identify opposite mass-balance responses to North Atlantic climate change, indicating differing ice-sheet sensitivities to mean climate state.
Abstract: The Scandinavian Ice Sheet (SIS) was an important component of the global ice sheet system during the last glaciation, but the timing of its growth to or retreat from its maximum extent remains poorly known. We used 115 cosmogenic beryllium-10 ages and 70 radiocarbon ages to constrain the timing of three substantial ice-margin fluctuations of the SIS between 25,000 and 12,000 years before the present. The age of initial deglaciation indicates that the SIS may have contributed to an abrupt rise in global sea level. Subsequent ice-margin fluctuations identify opposite mass-balance responses to North Atlantic climate change, indicating differing ice-sheet sensitivities to mean climate state.
249 citations
TL;DR: The combination of Fenton-like and the subsequent biological treatment resulted in the highest removal of PAH in creosote contaminated sand, and biodegradation with pre-ozonation was found to be the most effective technology for PAH elimination in peat.
210 citations
TL;DR: In this article, the authors considered widespread separation methods and an attempt is made to characterize them against the above-mentioned principles and provided a very good opportunity to improve analytical chemistry by replacing many chromatographic methods that consume large volumes of sol- vents.
Abstract: The introduction of the dimension of green chemistry into the assessment of ana- lytical methods should be a natural development trend in chemistry and should coincide with its general policy. Some of the principles of green chemistry—such as prevention of waste generation; safer solvents and auxiliaries; design for energy efficiency; safer chemistry to minimize the potential of chemical accidents; development of instrumental methods—are directly related to analytical chemistry. Analytical chemistry is considered to be a small-scale activity, but this is not always true in the case of controlling and monitoring laboratories whose number of runs performed is high. This makes an analytical laboratory comparable with the fine chemicals or pharma- ceutical industry. The use of instrumental methods instead of wet chemistry, automation, and minimization is a new trend in analytical chemistry, making this branch of chemistry more sustainable. In this study, widespread separation methods are considered and an attempt is made to characterize them against the above-mentioned principles. Special attention is given to cap- illary electrophoresis (CE), which provides a very good opportunity to improve analytical chemistry by replacing many chromatographic methods that consume large volumes of sol- vents. The choice of different solvents and micronization in analytical chemistry is also dis- cussed.
178 citations
TL;DR: A model in which AFD1/REC8 controls homologous pairing through its role in axial element elongation and the subsequent distribution of the recombination machinery independent of bouquet formation is provided.
Abstract: REC8 is a master regulator of chromatin structure and function during meiosis. Here, we dissected the functions of absence of first division ( afd1 ), a maize rec8/ α -kleisin homolog, using a unique afd1 allelic series. The first observable defect in afd1 mutants is the inability to make a leptotene chromosome. AFD1 protein is required for elongation of axial elements but not for their initial recruitment, thus showing that AFD1 acts downstream of ASY1/HOP1. AFD1 is associated with the axial and later the lateral elements of the synaptonemal complex. Rescuing 50% of axial element elongation in the weakest afd1 allele restored bouquet formation demonstrating that extent of telomere clustering depends on axial element elongation. However, rescuing bouquet formation was not sufficient for either proper RAD51 distribution or homologous pairing. It provides the basis for a model in which AFD1/REC8 controls homologous pairing through its role in axial element elongation and the subsequent distribution of the recombination machinery independent of bouquet formation.
147 citations
TL;DR: It is demonstrated that L1 ASP is capable of functioning as an alternative promoter, giving rise to a chimeric transcript whose coding region is identical to the ORF of mRNA of the following genes: KIAA1797, CLCN5, and SLCO1A2.
Abstract: Transcription of transposable elements interspersed in the genome is controlled by complex interactions between their regulatory elements and host factors. However, the same regulatory elements may be occasionally used for the transcription of host genes. One such example is the human L1 retrotransposon, which contains an antisense promoter (ASP) driving transcription into adjacent genes yielding chimeric transcripts. We have characterized 49 chimeric mRNAs corresponding to sense and antisense strands of human genes. Here we show that L1 ASP is capable of functioning as an alternative promoter, giving rise to a chimeric transcript whose coding region is identical to the ORF of mRNA of the following genes: KIAA1797, CLCN5, and SLCO1A2. Furthermore, in these cases the activity of L1 ASP is tissue-specific and may expand the expression pattern of the respective gene. The activity of L1 ASP is tissue-specific also in cases where L1 ASP produces antisense RNAs complementary to COL11A1 and BOLL mRNAs. Simultaneous assessment of the activity of L1 ASPs in multiple loci revealed the presence of L1 ASP-derived transcripts in all human tissues examined. We also demonstrate that L1 ASP can act as a promoter in vivo and predict that it has a heterogeneous transcription initiation site. Our data suggest that L1 ASP-driven transcription may increase the transcriptional flexibility of several human genes.
141 citations
TL;DR: New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone, with good to high levels of diastereo- and enantioselectivity.
127 citations
TL;DR: It was concluded that remediation of contaminated soil using in situ Fenton-like treatment will be more feasible at natural soil pH than chemical treatment of contaminants in sand matrix.
116 citations
TL;DR: In this article, the friction and wear behavior of cermets/steel rubbing pairs were investigated. Friction and wear tests were carried out using three different cremets on the base of tungsten, titanium and chromium carbides under dry sliding conditions against steel disk (0.45% C).
114 citations
01 Jan 2006
TL;DR: The authors argued that the idea of "creative destruction" entered the social sciences by way of Friedrich Nietzsche and used it in evolutionary economics to explain the difference between today's standard mainstream economics and the Schumpeterian alternative.
Abstract: This paper argues that the idea of ‘creative destruction’ enters the social sciences by way of Friedrich Nietzsche. The term itself is first used by German economist Werner Sombart, who openly acknowledges the influence of Nietzsche on his own economic theory. The roots of creative destruction are traced back to Indian philosophy, from where the idea entered the German literary and philosophical tradition. Understanding the origins and evolution of this key concept in evolutionary economics helps clarifying the contrasts between today’s standard mainstream economics and the Schumpeterian and evolutionary alternative.
114 citations
TL;DR: In this article, the authors used sol-gel spray pyrolysis to grow TiO 2 thin films onto silicon wafers at substrate temperatures between 315 and 500 °C using pulsed spray solution feed followed by annealing in the temperature interval from 500 to 800 °C in air.
TL;DR: Evidence of differences between Drosophila and vertebrates concerning signalling downstream of Smo, as well as in Smo itself is discussed and its importance for investigations of the pathway and related biology is discussed.
TL;DR: In this paper, the phase transformations, composition and micro-structural features in polycrystalline samples were studied by thermoanalytical methods (TGA/DTA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM).
TL;DR: In this paper, chemical bath deposition (CBD) and spray pyrolysis technique was used to reduce the series resistance of CdS/ITO structure by an order of magnitude.
TL;DR: In this article, high-shaped hexagonal rods were prepared by spray pyrolysis deposition of zinc chloride aqueous solutions in the temperature range of 490-560°C.
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20 Dec 2006TL;DR: In this article, a comparative study of IFT calculation methods was carried out to find a reliable technique for studied materials (WC-Co, TiC-Fe/Ni) Several IFT equations for ceramic materials, recommended by standards and publications, were used for the evaluation of the fracture toughness and compared with published conventional fracture toughness data.
Abstract: Majority of the fracture toughness studies of metallic materials typically use the Chevron notch technique, compact specimens and round notched tensile specimens These methods require considerable time for sample preparation and for the notch geometry control Only a few of them can be applied for cemented carbides due to the very high brittleness of the hard phase This is why various indentation fracture toughness (IFT) techniques have been developed [(superscript 1, 2)], which are more rapid and simple Indentation toughness measurements results depend critically on the assumption about the crack type (Palmqvist or median/radial cracks), on the equations used for the calculation of fracture toughness and on the material-dependent and material-independent constants [(superscript 3)] In the present work a comparative study of IFT calculation methods was carried out to find a reliable technique for studied materials (WC-Co, TiC-Fe/Ni) Several IFT equations for ceramic materials, recommended by standards and publications, were used for the evaluation of the fracture toughness and compared with published conventional fracture toughness data [(superscript 4, 5)] Only few of the equations give reliable estimation of the fracture toughness of cemented carbides
TL;DR: In this paper, the Cu-In-Ga precursors were selenized in a quartz tube furnace at 560 °C under the selenium pressure of 10 mbar.
TL;DR: Experimental blood-brain partition coefficients (logBB) for a diverse set of 113 drug molecules are correlated with computed structural descriptors using CODESSA-PRO and ISIDA programs to give statistically significant QSAR models based respectively, on molecular and on fragment descriptors.
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TL;DR: In this paper, information about freak wave events in the ocean reported by mass media and derived from personal observations in 2005 is collected and analyzed, and nine cases are selected as true freakwave events from a total number of 27 mentioned.
Abstract: Information about freak wave events in the ocean reported by mass media and derived from personal observations in 2005 is collected and analysed. Nine cases are selected as true freak wave events from a total number of 27 mentioned. Besides rogue waves in the open sea, the problem of freak wave events on the shore is emphasized. These accidents are related to unexpected wave impact upon the coast and shore constructions or to sudden intensive flooding of the coast. Of the nine events considered reliable here, three events correspond to open-sea cases, while the six others occurred nearshore.
TL;DR: In this paper, the results showed that P. placenta tended to degrade cellulose amorphous regions more readily, while C. puteana, possessing full enzyme complement, was able to degrade both amorphus and crystalline regions more easily.
TL;DR: In normal adult cardiomyocytes and HL-1 cells intracellular local restrictions of diffusion of adenine nucleotides and metabolic feedback regulation of respiration via phosphotransfer networks are different, most probably related to differences in structural organization of these cells.
TL;DR: The Millefolii herba grown in Estonia conforms to the European Pharmacopoeia (EP) standards in the aspect of the essential oil contents and contains high amounts of monoterpenes and chamazulene.
TL;DR: In this paper, the authors investigated the sedimentary history of some Lateglacial and Holocene depositional sites of Lithuanian dunes and found that the termination of the aeolian processes in the continental part of Lithuania is correlated with the end of the Atlantic or the beginning of the Subboreal period.
Abstract: Sand dunes are common along the sea coasts of Lithuania and in some regions of the mainland part of the country. Until recently, the age of the aeolian deposits was only approximate because of the lack of radiocarsbon-dating of soils buried in dune deposits. A relatively new alternative method to direct dating of organic-free deposits is infra-red optically stimulated luminescence (IR-OSL). Using this method, we investigated the sedimentary history of some Lateglacial and Holocene depositional sites of Lithuanian dunes. The samples for IR-OSL dating have been taken from boreholes (Manciagire, Smalininkai, Žalioji Giria) and outcrops (Manciagire and Ventes Ragas) in different dune massifs. The results indicate that the aeolian sedimentation in Lithuania started during the Younger Dryas. The termination of the aeolian processes in the continental part of Lithuania is correlated with the end of the Atlantic or the beginning of the Subboreal period; this can be explained by significant climatic changes during the Atlantic period. There were several periods of high aeolian activity during the Holocene, but these are asynchronous in different dune massifs and variations in the sedimentation rate occurred both vertically over the section and spatially across the massif.
TL;DR: The use of recursive coalgebras as a paradigm of structured recursion in programming semantics is motivated and new conditions for the recursiveness of a coalgebra based on comonads, comonad-coalgebrAs and distributive laws of functors over comonADs are given.
Abstract: The concept of recursive coalgebra of a functor was introduced in the 1970s by Osius in his work on categorical set theory to discuss the relationship between wellfounded induction and recursively specified functions. In this paper, we motivate the use of recursive coalgebras as a paradigm of structured recursion in programming semantics, list some basic facts about recursive coalgebras and, centrally, give new conditions for the recursiveness of a coalgebra based on comonads, comonad-coalgebras and distributive laws of functors over comonads. We also present an alternative construction using countable products instead of coffee comonads.
TL;DR: The potential of carbon isotope excursions as a stratigraphic correlation tool has been proved by several earlier studies, but partly indistinct biostratigraphic definition hinders their usage as mentioned in this paper.
Abstract: The potential of carbon isotope excursions as a stratigraphic correlation tool has been proved by several earlier studies, but partly indistinct biostratigraphic definition hinders their usage. Six positive carbon isotope excursions have been established in the Baltic Silurian (values of the first four in the East Baltic): the early Aeronian excursion (peak δ13C values reach +3.7‰); the early Telychian excursion (+2.7‰); the early Sheinwoodian excursion (+5.2‰); the middle to late Homerian double-peaked excursion (+4.6‰); the late Gorstian excursion (+1.1‰, in Gotland) and the middle Ludfordian excursion—the most prominent shift in the Phanerozoic (maximum values reach in the East Baltic +8.2‰, in Scania +11.2‰).The biostratigraphic dating of three Wenlock and Ludlow excursions (the early Sheinwoodian, mid to late Homerian and mid-Ludfordian) is discussed and refined in the paper and despite minor problems, these could successfully serve as a tool for geological correlation and as chronostratigra...
TL;DR: In this article, the variability of solar radiation in the minute-long time range was studied and the distribution functions were found to be a superposition of two exponential functions with different exponents, which depend on the magnitude of the radiation increments.
TL;DR: Density-functional theory plane-wave modeling of fluor- and hydroxyapatites has been performed, and it was found that cadmium ions favor Ca(1) positions in fluorapatite and Ca(2) positions on the hexagonal axis, in agreement with experiment.
TL;DR: The organization, stability, and the pathway of metal-thiolate cluster assembly in MT-4 reconstituted with Cd2+ and Co2+ ions are reported on.
TL;DR: It is demonstrated that ASK1 is essential for early nuclear reorganization events and raised the interesting possibility that AsK1 controls chromatin structure by targeting of either an early regulator of meiotic progression or possibly matrix attachment proteins for destruction.
Abstract: During early stages of meiotic prophase I the nucleus undergoes considerable reorganization, including the clustering of telomeres, the release of contacts between chromosomes and the nuclear membrane, the reorganization of the nucleolus, and chromatin remodeling. Using a light squashing technique for the analysis of meiotic chromosomes along with fluorescent in situ hybridization, transmission electron microscopy and immunolocalization studies with antibodies to modified histones, we demonstrate that ASK1 is essential for early nuclear reorganization events. A relatively large number of meiotic alterations have been identified in ask1-1 plants. We show that many of these defects, including alterations in homolog pairing, nucleolus migration and the missegregation of chromosomes, may arise from alterations in chromatin structure and the inability of chromosomes to resolve and release properly from the nuclear membrane and nucleolus during leptotene. These results raise the interesting possibility that ASK1 controls chromatin structure by targeting of either an early regulator of meiotic progression or possibly matrix attachment proteins for destruction.
TL;DR: A combination of modified Fenton and biological treatment was used to remove polycyclic aromatic hydrocarbons from creosote oil-contaminated soil and the toxicity of column leachate and soil to Vibrio fischeri increased.
Abstract: A combination of modified Fenton and biological treatment was used to remove polycyclic aromatic hydrocarbons (PAHs) from creosote oil-contaminated soil. After modified Fenton reaction the toxicity of column leachate and soil to Vibrio fischeri increased. The number of intact bacterial cells and utilisation of PAHs in PAH utilisation microplate assay decreased after modified Fenton reaction. However, bacteria in chemically treated soil utilised PAHs without addition of other carbon sources. The activity of extracellular esterases increased during incubation of modified Fenton-treated soil. PAH removal in combined chemical oxidation and incubation (43–59%) was higher than in incubation alone (22–30%). Residual H2O2 in soil allowed chemical oxidation of PAHs during incubation. Copyright © 2006 Society of Chemical Industry