| 1. |
- Verlaak, Stijn, et al.
(författare)
-
Electronic Structure and Geminate Pair Energetics at Organic-Organic Interfaces: The Case of Pentacene/C-60 Heterojunctions
- 2009
-
Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 19:23, s. 3809-3814
-
Tidskriftsartikel (refereegranskat)abstract
- Organic semiconductors are characterized by localized states whose energies are predominantly determined by electrostatic interactions with their immediate molecular environment. As a result, the details of the energy landscape at heterojunctions between different organic semiconductors cannot simply be deduced from those of the individual semiconductors, and they have so far remained largely unexplored. Here, microelectrostatic computations are performed to clarify the nature of the electronic structure and geminate pair energetics at the pentacene/C-60 interface, as archetype for an interface between a donor molecule and a fullerene electron acceptor. The size and orientation of the molecular quadrupole moments, determined by material choice, crystal orientation, and thermodynamic growth parameters of the semiconductors, dominate the interface energetics. Not only do quadrupoles produce direct electrostatic interactions with charge carriers, but, in addition, the discontinuity of the quadrupole field at the interface induces permanent interface dipoles. That discontinuity is particularly striking for an interface with C-60 molecules, which by virtue of their symmetry possess no quadrupole. Consequently, at a pentacene/C-60 interface, both the vacuum-level shift and geminate pair dissociation critically depend on the orientation of the pentacene pi-system relative to the adjacent C-60.
|
|
| 2. |
- Chen, Nansheng, et al.
(författare)
-
Identification of ciliary and ciliopathy genes in Caenorhabditis elegans through comparative genomics
- 2006
-
Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 7:12, s. R126-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The recent availability of genome sequences of multiple related Caenorhabditis species has made it possible to identify, using comparative genomics, similarly transcribed genes in Caenorhabditis elegans and its sister species. Taking this approach, we have identified numerous novel ciliary genes in C. elegans, some of which may be orthologs of unidentified human ciliopathy genes. Results: By screening for genes possessing canonical X-box sequences in promoters of three Caenorhabditis species, namely C. elegans, C. briggsae and C. remanei, we identified 93 genes ( including known X-box regulated genes) that encode putative components of ciliated neurons in C. elegans and are subject to the same regulatory control. For many of these genes, restricted anatomical expression in ciliated cells was confirmed, and control of transcription by the ciliogenic DAF-19 RFX transcription factor was demonstrated by comparative transcriptional profiling of different tissue types and of daf-19(+) and daf-19(-) animals. Finally, we demonstrate that the dye-filling defect of dyf-5( mn400) animals, which is indicative of compromised exposure of cilia to the environment, is caused by a nonsense mutation in the serine/threonine protein kinase gene M04C9.5. Conclusion: Our comparative genomics-based predictions may be useful for identifying genes involved in human ciliopathies, including Bardet-Biedl Syndrome ( BBS), since the C. elegans orthologs of known human BBS genes contain X-box motifs and are required for normal dye filling in C. elegans ciliated neurons.
|
|
| 3. |
- Raffalli-Mathieu, Francoise, et al.
(författare)
-
Differences between bovine and human steroid double-bond isomerase activities of Alpha-class glutathione transferases selectively expressed in steroidogenic tissues
- 2007
-
Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 0304-4165 .- 1872-8006. ; 1770:1, s. 130-136
-
Tidskriftsartikel (refereegranskat)abstract
- Bovine glutathione transferase A1-1 (bGST A1-1) and human GST A3-3 (hGST A3-3) share both high amino acid sequence similarity and selective expression in steroidogenic organs. hGST A3-3 is the most efficient steroid isomerase known in mammals, and is thought to catalyze isomerization reactions in the biosynthesis of steroid hormones. We observed that four out of five residues essential to the high steroid isomerase activity of hGST A3-3 are conserved in bGST A1-1. The bovine GST was cloned, heterologously expressed, and purified to homogeneity. Its specific activity towards classical GST substrates and two steroids, Delta(5)-androstene-3,17-dione and Delta(5)-pregnene-3,20-dione, was studied, and the steady-state kinetic parameters with the steroids were determined. We find that bGST A1-1 exhibits enzymatic activities comparable to those of hGST A3-3 towards non-steroid substrates. However, the bovine enzyme had 100 times lower catalytic efficiency in steroid isomerization reactions than the human GST. Nevertheless, bGST A1-1 was found as efficient as bovine 3 beta-hydroxysteroid dehydrogenase as a steroid isomerase. We discuss likely reasons for the contrasting steroid isomerase activities of bGST AM and hGST A3-3, and alternative roles of bGST A1-1.
|
|
| 4. |
- Rousseau-Gueutin, Mathieu, et al.
(författare)
-
Comparative genetic mapping between octoploid and diploid Fragaria species reveals a high level of colinearity between their genomes and the essentially disomic behavior of the cultivated octoploid strawberry
- 2008
-
Ingår i: Genetics. - : OXFORD UNIV PRESS INC. - 0016-6731 .- 1943-2631. ; 179:4, s. 2045-2060
-
Tidskriftsartikel (refereegranskat)abstract
- Macrosynteny and colinearity between Fragaria (strawberry) species showing extreme levels of ploidy have been studied through comparative genetic mapping between the octoploid cultivated strawberry. (F x ananassa) and its diploid relatives. A comprehensive map of the octoploid strawberry, in which almost all linkage groups are ranged into the seven expected homoeologeous groups was obtained, thus providing were observed between homo(eo)logous linkage groups and between the octoploid homoeologous groups and their corresponding diploid linkage groups. These results reveal that the polyploidization events that took place along the evolution of the Fragaria genus and the more recent juxtaposition of two octoploid strawberry genomes in the cultivated strawberry did not trigger any major chromosomal rearrangements in genomes involved in F. x ananassa. They further suggest the existence of a close levels of polysomic segregation suggested by the observation of large linkage groups in coupling phase only, the prevalence of linkage groups in coupling/replusion phase clearly demonstrates that the meiotic behavior is mainly disomic in the cultivated strawberry.
|
|
| 5. |
- Simon-Bouy, Brigitte, et al.
(författare)
-
Hypophosphatasia: molecular testing of 19 prenatal cases and discussion about genetic counseling.
- 2008
-
Ingår i: Prenatal diagnosis. - : Wiley. - 0197-3851 .- 1097-0223. ; 28:11, s. 993-8
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We studied hypophosphatasia (HP) mutations in 19 cases prenatally detected by ultrasonography without familial history of HP. We correlated the mutations with the reported ultrasound signs, and discussed genetic counseling with regard to the particular dominantly inherited prenatal benign form of HP. METHOD: The coding sequence of the tissue nonspecific alkaline phosphatase (TNSALP) gene was analyzed by DNA sequencing, and 3D modeling was used to locate the mutated amino acids with regard to the functional domains of TNSALP. RESULTS: Although reported ultrasound signs were heterogeneous, two mutated alleles were found in 18 of the 19 cases studied, indicating recessive transmission of the disease. Functional domains of TNSALP were affected by 74% of missense mutations. In all the cases, including one with only a heterozygous mutation, molecular, biological, and familial data do not corroborate the hypothesis of prenatal benign HP. The mutation c.1133A>T observed in the prenatal benign form of HP and common in USA was not found in this series. CONCLUSION: The results point out the prenatally detectable allelic heterogeneity of HP. The nature of the detected mutations and the evidence of recessive inheritance do not support these cases being affected with prenatal benign HP.
|
|
