Deletion of the Nucleotide Excision Repair Gene Ercc1 Reduces Immunoglobulin Class Switching and Alters Mutations Near Switch Recombination Junctions

The structure-specific endonuclease ERCC1-XPF is an essential component of the nucleotide excision DNA repair pathway. ERCC1-XPF nicks double-stranded DNA immediately adjacent to 3′ single-strand regions. Substrates include DNA bubbles and flaps. Furthermore, ERCC1 interacts with Msh2, a mismatch repair (MMR) protein involved in class switch recombination (CSR). Therefore, ERCC1-XPF has abilities that might be useful for antibody CSR. We tested whether ERCC1 is involved in CSR and found that Ercc1−/− splenic B cells show moderately reduced CSR in vitro, demonstrating that ERCC1-XPF participates in, but is not required for, CSR. To investigate the role of ERCC1 in CSR, the nucleotide sequences of switch (S) regions were determined. The mutation frequency in germline Sμ segments and recombined Sμ-Sγ3 segments cloned from Ercc1−/− splenic B cells induced to switch in culture was identical to that of wild-type (WT) littermates. However, Ercc1−/− cells show increased targeting of the mutations to G:C bp in RGYW/WRCY hotspots and mutations occur at sites more distant from the S–S junctions compared with WT mice. The results indicate that ERCC1 is not epistatic with MMR and suggest that ERCC1 might be involved in processing or repair of DNA lesions in S regions during CSR

Spatial Light Modulators for the Manipulation of Individual Atoms

We propose a novel dipole trapping scheme using spatial light modulators (SLM) for the manipulation of individual atoms. The scheme uses a high numerical aperture microscope to map the intensity distribution of a SLM onto a cloud of cold atoms. The regions of high intensity act as optical dipole force traps. With a SLM fast enough to modify the trapping potential in real time, this technique is well suited for the controlled addressing and manipulation of arbitrarily selected atoms.Comment: 9 pages, 5 figure

Micropaleontological counting methods and techniques : an exercise on an eight metres section of the lower Pliocene of Capo Rossello, Sicily

The LG.C.P. project 74/1/1 "a systems approach to accuracy in time", aims at a quantification of the refinement that may be attained with various methods of stratigraphic correlation. A considerable part of the pilot studies carried out by the "Dutch" working group deals with the application of numerical methods in biostratigraphy, in which one of the lines of research aims at a better understanding of counted numbers of specimens of individual taxa in suites of samples, as presented in so-called distribution charts or range charts. The biozonations constructed from such charts, from which in practice the more general zonation schemes are compiled, are commonly based on entries and exits of indivual taxa or groups of taxa. The corresponding datum levels based on single or multiple presence-absence criteria (as well as relatively high frequencies of taxa, so-called acmes) determine the zones recognized in the vertical successions. These methods and the actual counting on which they are - often unconsciously - based are being evaluated by the Utrecht team for several sections of the Mediterranean Neogene. The purpose of the present investigation was only to obtain a better documented insight in the reliability of different methods of collecting quantitative data

Beitraege zur Bauwerksaerodynamik

SIGLEAvailable from TIB Hannover: FR 4907+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Polycistronic expression of a ß-carotene biosynthetic pathway in Saccharomyces cerevisiae coupled to ß-ionone production

The flavour and fragrance compound ß-ionone, which naturally occurs in raspberry and many other fruits and flowers, is currently produced by synthetic chemistry. This study describes a synthetic biology approach for ß-ionone production from glucose by Saccharomyces cerevisiae that is partially based on polycistronic expression. Experiments with model proteins showed that the T2A sequence of the Thosea asigna virus mediated efficient production of individual proteins from a single transcript in S. cerevisiae. Subsequently, three ß-carotene biosynthesis genes from the carotenoid-producing ascomycete Xanthophyllomyces dendrorhous (crtI, crtE and crtYB) were expressed in S. cerevisiae from a single polycistronic construct. In this construct, the individual crt proteins were separated by T2A sequences. Production of the individual proteins from the polycistronic construct was confirmed by Western blot analysis and by measuring the production of ß-carotene. To enable ß-ionone production, a carotenoid-cleavage dioxygenase from raspberry (RiCCD1) was co-expressed in the ß-carotene producing strain. In glucose-grown cultures with a second phase of dodecane, ß-ionone and geranylacetone accumulated in the organic phase. Thus, by introducing a polycistronic construct encoding a fungal carotenoid pathway and an expression cassette encoding a plant dioxygenase, a novel microbial production system has been established for a fruit flavour compound

Prototypanlage Nukleare Prozesswaerme (PNP), Referenzphase. F+E-Arbeiten zur Hydrierenden Kohlevergasung (HKV) Fortfuehrung des Betriebes der halbtechnischen Anlage zur Hydrierenden Kohlevergasung. Schlussbericht

With 15 refs., 6 tabs., 15 figs.Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman