3,400 research outputs found
CRISPR-mediated targeted mRNA degradation in the archaeon Sulfolobus solfataricus
No full textEuropean SulfoSYS-project [SysMo P–N-01-09-23] and grant [9P23000 and P25369] by the Austrian Research fund (to C.S.) and by grant [BB/K000314/1] from the Biotechnology and Biological Sciences Research Council (to M.F.W.). Funding for open access charge: Austrian Science Fund.The recently discovered clustered regularly interspaced short palindromic repeat (CRISPR)-mediated virus defense represents an adaptive immune system in many bacteria and archaea. Small CRISPR RNAs cause cleavage of complementary invading nucleic acids in conjunction with an associated protein or a protein complex. Here, we show CRISPR-mediated cleavage of mRNA from an invading virus in the hyperthermophilic archaeon Sulfolobus solfataricus. More than 40% of the targeted mRNA could be cleaved, as demonstrated by quantitative polymerase chain reaction. Cleavage of the mRNA was visualized by northern analyses and cleavage sites were mapped. In vitro, the same substrates were cleaved by the purified CRISPR-associated CMR complex from Sulfolobus solfataricus. The in vivo system was also re-programmed to knock down mRNA of a selected chromosomal gene (β-galactosidase) using an artificial miniCRISPR locus. With a single complementary spacer, ∼50% reduction of the targeted mRNA and of corresponding intracellular protein activity was achieved. Our results demonstrate in vivo cleavage of mRNA in a prokaryote mediated by small RNAs (i.e. analogous to RNA interference in eukaryotes) and the re-programming of the system to silence specific genes of interest.Peer reviewe
Genome-based reclassification of Picrophilus torridus Zillig et al. 1996 as a later heterotypic synonym of Picrophilus oshimae Schleper et al. 1996
No full textIn the present study, we attempt to clarify the taxonomic positions of Picrophilus oshimae and Picrophilus torridus . The 16S rRNA gene sequence similarity between P. oshimae DSM 9789T and P. torridus DSM9790T (99.4 %) was above the threshold value (98.6 %) for bacterial species delineation. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between P. oshimae DSM 9789T and P. torridus DSM9790T were higher than the threshold values (95–96 % for ANI and 70 % for dDDH) for bacterial species delineation. The present results indicate that Picrophilus torridus Zillig et al. 1996 is a later heterotypic synonym of Picrophilus oshimae Schleper et al. 1996
Iptycene-Containing Azaacenes with Tunable Luminescence
No full textAn optimized route toward iptycene-capped, p-dibromo-quinoxalinophenazine was developed, increasing the yield significantly from literature procedures. New iptycene-containing symmetrical azaacenes were synthesized from this intermediate using Suzuki–Miyaura cross-coupling, and their photophysical properties were evaluated. Tuning the substituents allows modulating emission wavelengths across the visible spectrum. Substitution with 3-methoxy-2-methylthiophene exhibits a quantum yield of 35%. The (triisopropylsilyl)acetylene product has a quantum yield of 38% and serves as a model compound for the synthesis of polymers based on this electrooptically active molecular motif. Keywords: N-heteroiptycene - Suzuki–Miyaura cross-coupling - Sonogashira coupling - pyrazinoquinoxaline - luminescenceUnited States. Air Force. Office of Scientific Researc
Genome sequence of Picrophilus torridus and its implications for life around pH 0
No full textThe euryarchaea Picrophilus torridus and Picrophilus oshimae are able to grow around pH 0 at up to 65degreesC, thus they represent the most thermoacidophilic organisms known. Several features that may contribute to the thermoaciclophilic survival strategy of A torridus were deduced from analysis of its 1.55-megabase genome. A torridus has the smallest genome among nonparasitic aerobic microorganisms growing on organic substrates and simultaneously the highest coding density among thermoacidophiles. An exceptionally high ratio of secondary over ATP-consuming primary transport systems demonstrates that the high proton concentration in the surrounding medium is extensively used for transport processes. Certain genes that may be particularly supportive for the extreme lifestyle of P. torridus appear to have been internalized into the genome of the Picrophilus lineage by horizontal gene transfer from crenarchaea and bacteria. Finally, it is noteworthy that the thermoaciclophiles from phylogenetically distant branches of the Archaea apparently share an unexpectedly large pool of genes
Measurement of D*+- meson production and F2(c) in deep inelastic scattering at HERA
No full textDESY-HERA. Measurement of the inclusive production of D*(2010)+- mesons in DIS of 27.5 GeV positrons and 820 GeV protons with a centre of mass energy of 300 GeV. The data were taken during the 1996 and 1997 HERA running periods and have an integrated luminosity of 18.6 pb-1. Numerical values were supplied by P. Schleper
Responses of hyperthermophilic crenarchaea to UV irradiation
No full textThis work was supported by a dedicated functional genomics grant from the Swedish Research Council and the Swedish Graduate Research School in Genomics and Bioinformatics to RB, and by grants from the Wellcome Trust and BBSRC to MFW.Background: DNA damage leads to cellular responses that include the increased expression of DNA repair genes, repression of DNA replication and alterations in cellular metabolism. Archaeal information processing pathways resemble those in eukaryotes, but archaeal damage response pathways remain poorly understood. Results: We analyzed the transcriptional response to UV irradiation in two related crenarchaea, Sulfolobus solfataricus and Sulfolobus acidocaldarius. Sulfolobus species encounter high levels of DNA damage in nature, as they inhabit high temperature, aerobic environments and are exposed to sunlight. No increase in expression of DNA repair genes following UV irradiation was observed. There was, however, a clear transcriptional response, including repression of DNA replication and chromatin proteins. Differential effects on the expression of the three transcription factor B ( tfb) genes hint at a mechanism for the modulation of transcriptional patterns in response to DNA damage. TFB3, which is strongly induced following UV irradiation, competes with TFB1 for binding to RNA polymerase in vitro, and may act as a repressor of transcription or an alternative transcription factor for certain promoters. Conclusion: A clear response to DNA damage was observed, with down-regulation of the DNA replication machinery, changes in transcriptional regulatory proteins, and up-regulation of the biosynthetic enzymes for beta-carotene, which has UV protective properties, and proteins that detoxify reactive oxygen species. However, unlike eukaryotes and bacteria, there was no induction of DNA repair proteins in response to DNA damage, probably because these are expressed constitutively to deal with increased damage arising due to high growth temperatures.Peer reviewe
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