On Conserved Current in Markovian Open Quantum Systems

We reexamine the markovian approximation of local current in open quantum systems, discussed recently by Gebauer and Car. Our derivation is more transparent, the proof of current conservation becomes explicit and easy.Comment: 3 page

How two become one: HJURP dimerization drives CENP-A assembly

CENP‐A containing nucleosomes epigenetically specify centromere position on chromosomes. Deposition of CENP‐A into chromatin is mediated by HJURP, a specific CENP‐A chaperone. Paradoxically, HJURP binding sterically prevents dimerization of CENP‐A, which is critical to form functional centromeric nucleosomes. A recent publication in The EMBO Journal (Zasadzińska et al, 2013) demonstrates that HJURP itself dimerizes through a C‐terminal repeat region, which is essential for centromeric assembly of nascent CENP‐A.FCT fellowship: (SFRH/BD/74284/2010); FCT grants: (BIA-BCM/100557/2008, BIAPRO/100537/2008); EMBO Installation Grant

Relationships between ecosystems and plant assemblages as responses to environmental conditions in the Lower Jurassic of Hungary and Romania

Two Early Jurassic localities, the Mecsek Mts in Hungary and Anina in Romania, are similarly significant and both floras are of autochthonous/paraautochthonous origin. In the Early Jurassic the Hungarian locality was a delta plain; the Romanian locality was an intramontane depression filled predominantly by a braided river system. The floristic composition of the two localities (52 genera, 120 species), although superficially similar (25 common genera), differs at species level (only 9 common species) as well as in the proportions of taxa in major plant groups. These differences can be explained by differences in environmental conditions resulting from palaeogeographic and topographic factors. Based on previous and recent studies, alpha diversity as well as statistically (DCA, PCA) differentiated ecogroups are compared and discussed. For common species, the GLM method was used to classify them to particular environmental response types. Their environmental requirements in both ecosystems are evaluated. Some of the shared species showed different preferences at the localities, explainable by their broad ecological tolerance

Outline analysis of the grapevine (Vitis vinifera L.) berry shape by elliptic Fourier descriptors

Grapevine berry morphology is one of the most important features in table grape production. In this study, berry samples of 46 grapevine accessions were investigated for 3 consecutive years with elliptic Fourier descriptors (EFD) to evaluate shape diversity. Ten reference shapes obtained from the OIV descriptor list were involved and principal component (PC) scores summarizing the EFD's were statistically evaluated with Two way ANOVA and discriminant analysis. The cummulative contribution of the five principal components was 96.83 %. Two way ANOVA revealed that berry shape had high variability within the accessions and years. Based on the linear discriminant analysis, reference shapes were compared to those of the accessions and graphic reconstruction was carried out. OIV references were considered as unknown samples and grouped into the accession classes. Overall correct classification of the accessions into their group was 13.88 %. Our results showed that EFD together with reference shapes are a powerful method to discribe berry shape and possibly give the future basis of uvometric evaluation of grapevine cultivars

Graled (Grapevine leaf digitalization) Software for the Detection and Graphic Reconstruction of Ampelometric Differences Between Vitis Leaves

Raster graphic ampelometric software was not exclusively developed for the estimation of leaf area, but also for the characterization of grapevine (Viti vinifera L.) leaves. The software was written in C-Hprogramming language, using the C-1-1- Builder 2007 for Windows 95-XP and Linux operation systems. It handles desktop-scanned images. On the image analysed with the GRA.LE.D., the user has to determine 11 points. These points are then connected and the distances between them calculated. The GRA.LE.D. software supports standard ampelometric measurements such as leaf area, angles between the veins and lengths of the veins. These measurements are recorded by the software and exported into plain ASCII text files for single or multiple samples. Twenty-two biometric data points of each leaf are identified by the GRA.LE.D. It presents the opportunity to statistically analyse experimental data, allows comparison of cultivars and enables graphic reconstruction of leaves using the Microsoft Excel Chart Wizard. The GRA. LE.D. was thoroughly calibrated and compared to other widely used instruments and methods such as photo-gravimetry, LiCor L0100, WinDIAS2.0 and ImageTool. By comparison, the GRA.LE.D. presented the most accurate measurements of leaf area, but the LiCor L0100 and the WinDIAS2.0 were faster, while the photo-gravimetric method proved to be the most time-consuming. The WinDIAS2.0 instrument was the least reliable. The GRA.LE.D. is uncomplicated, user-friendly, accurate, consistent, reliable and has wide practical application

Assembly in G1 phase and long-term stability are unique intrinsic features of CENP-A nucleosomes

Centromeres are the site of kinetochore formation during mitosis. Centromere protein A (CENP-A), the centromere-specific histone H3 variant, is essential for the epigenetic maintenance of centromere position. Previously we showed that newly synthesized CENP-A is targeted to centromeres exclusively during early G1 phase and is subsequently maintained across mitotic divisions. Using SNAP-based fluorescent pulse labeling, we now demonstrate that cell cycle-restricted chromatin assembly at centromeres is unique to CENP-A nucleosomes and does not involve assembly of other H3 variants. Strikingly, stable retention is restricted to the CENP-A/H4 core of the nucleosome, which we find to outlast general chromatin across several cell divisions. We further show that cell cycle timing of CENP-A assembly is independent of centromeric DNA sequences and instead is mediated by the CENP-A targeting domain. Unexpectedly, this domain also induces stable transmission of centromeric nucleosomes, independent of the CENP-A deposition factor HJURP. This demonstrates that intrinsic properties of the CENP-A protein direct its cell cycle-restricted assembly and induces quantitative mitotic transmission of the CENP-A/H4 nucleosome core, ensuring long-term stability and epigenetic maintenance of centromere position.FCT fellpwships: (SFRH/BD/74284/2010, SFRH/BPD/69115/2010), National Institutes of Health grant: (GM082989), Burroughs Wellcome Fund (Career Award in the Biomedical Sciences), Rita Allen Foundation Scholar Award, Instituto Gulbenkian de Ciência, European Commission FP7 Program, EMBO

GRA.LE.D. (GRApevine LEaf Digitalization) Software for the Detection and Graphic Reconstruction of Ampelometric Differences Between Vitis Leaves

Raster graphic ampelometric software was not exclusively developed for the estimation of leaf area,but also for the characterization of grapevine (Viti vinifera L.) leaves. The software was written in C++programming language, using the C++ Builder 2007 for Windows 95-XP and Linux operation systems. Ithandles desktop-scanned images. On the image analysed with the GRA.LE.D., the user has to determine11 points. These points are then connected and the distances between them calculated. The GRA.LE.D.software supports standard ampelometric measurements such as leaf area, angles between the veins andlengths of the veins. These measurements are recorded by the software and exported into plain ASCII textfiles for single or multiple samples. Twenty-two biometric data points of each leaf are identified by theGRA.LE.D. It presents the opportunity to statistically analyse experimental data, allows comparison ofcultivars and enables graphic reconstruction of leaves using the Microsoft Excel Chart Wizard. The GRA.LE.D. was thoroughly calibrated and compared to other widely used instruments and methods such asphoto-gravimetry, LiCor Li3100, WinDIAS2.0 and ImageTool. By comparison, the GRA.LE.D. presentedthe most accurate measurements of leaf area, but the LiCor Li3100 and the WinDIAS2.0 were faster, whilethe photo-gravimetric method proved to be the most time-consuming. The WinDIAS2.0 instrument wasthe least reliable. The GRA.LE.D. is uncomplicated, user-friendly, accurate, consistent, reliable and haswide practical application

Cdk Activity Couples Epigenetic Centromere Inheritance to Cell Cycle Progression

Centromeres form the site of chromosome attachment to microtubules during mitosis. Identity of these loci is maintained epigenetically by nucleosomes containing the histone H3 variant CENP-A. Propagation of CENP-A chromatin is uncoupled from DNA replication initiating only during mitotic exit. We now demonstrate that inhibition of Cdk1 and Cdk2 activities is sufficient to trigger CENP-A assembly throughout the cell cycle in a manner dependent on the canonical CENP-A assembly machinery. We further show that the key CENP-A assembly factor Mis18BP1(HsKNL2) is phosphorylated in a cell cycle-dependent manner that controls its centromere localization during mitotic exit. These results strongly support a model in which the CENP-A assembly machinery is poised for activation throughout the cell cycle but kept in an inactive noncentromeric state by Cdk activity during S, G2, and M phases. Alleviation of this inhibition in G1 phase ensures tight coupling between DNA replication, cell division, and subsequent centromere maturation.FCT doctoral fellowship: (SFRH/BD/33219/2007); FCT grant: (BIA-BCM/100557/2008); Fundação Calouste Gulbenkian; European Commission FP7 programme; EMBO installation grant