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951.
Background
DNA barcoding, i.e. the use of a 648 bp section of the mitochondrial gene cytochrome c oxidase I, has recently been promoted as useful for the rapid identification and discovery of species. Its success is dependent either on the strength of the claim that interspecific variation exceeds intraspecific variation by one order of magnitude, thus establishing a "barcoding gap", or on the reciprocal monophyly of species.Results
We present an analysis of intra- and interspecific variation in the butterfly family Lycaenidae which includes a well-sampled clade (genus Agrodiaetus) with a peculiar characteristic: most of its members are karyologically differentiated from each other which facilitates the recognition of species as reproductively isolated units even in allopatric populations. The analysis shows that there is an 18% overlap in the range of intra- and interspecific COI sequence divergence due to low interspecific divergence between many closely related species. In a Neighbour-Joining tree profile approach which does not depend on a barcoding gap, but on comprehensive sampling of taxa and the reciprocal monophyly of species, at least 16% of specimens with conspecific sequences in the profile were misidentified. This is due to paraphyly or polyphyly of conspecific DNA sequences probably caused by incomplete lineage sorting.Conclusion
Our results indicate that the "barcoding gap" is an artifact of insufficient sampling across taxa. Although DNA barcodes can help to identify and distinguish species, we advocate using them in combination with other data, since otherwise there would be a high probability that sequences are misidentified. Although high differences in DNA sequences can help to identify cryptic species, a high percentage of well-differentiated species has similar or even identical COI sequences and would be overlooked in an isolated DNA barcoding approach. 相似文献952.
Farwanah H Pierstorff B Schmelzer CE Raith K Neubert RH Kolter T Sandhoff K 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,852(1-2):562-570
Ceramides covalently bound to keratinocytes are essential for the barrier function of the skin, which can be disturbed in diseases, such as psoriasis and atopic dermatitis. These ceramides of the classes omega-hydroxyacyl-sphingosine and omega-hydroxyacyl-6-hydroxysphingosine contain an omega-hydroxy fatty acid. For their separation and identification, a new analytical approach based on normal phase liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry and tandem nano-electrospray mass spectrometry, respectively, is presented here. Tandem mass spectrometry provided structural information about the sphingoid base as well as the fatty acid moieties. The chain lengths of the bases ranged from C12 to C22, the chain lengths of the fatty acids varied between C28 and C36. In total, 67 ceramide species have been identified in human skin. The analytical methods presented in this work can be helpful for investigating alterations in the ceramide composition of the skin as seen in psoriasis, atopic dermatitis, and diseases with impaired epidermal barrier function. 相似文献
953.
Perceptual events derive their significance to an animal from their meaning about the world, that is from the information they carry about their causes. The brain should thus be able to efficiently infer the causes underlying our sensory events. Here we use multisensory cue combination to study causal inference in perception. We formulate an ideal-observer model that infers whether two sensory cues originate from the same location and that also estimates their location(s). This model accurately predicts the nonlinear integration of cues by human subjects in two auditory-visual localization tasks. The results show that indeed humans can efficiently infer the causal structure as well as the location of causes. By combining insights from the study of causal inference with the ideal-observer approach to sensory cue combination, we show that the capacity to infer causal structure is not limited to conscious, high-level cognition; it is also performed continually and effortlessly in perception. 相似文献
954.
Daniela Schilling Fabian Tetzlaff Sarah Konrad Wei Li Gabriele Multhoff 《Cell stress & chaperones》2015,20(1):139-147
Recent findings suggest that hypoxia of the tumor microenvironment contributes to immune escape from natural killer (NK) cell-mediated cytotoxicity. Heat shock protein 70 (Hsp70) and the stress-regulated major histocompatibility class I chain-related protein A and B (MICA/B) both serve as ligands for activated NK cells when expressed on the cell surface of tumor cells. Herein, we studied the effects of hypoxia and hypoxia-inducible factor-1α (HIF-1α) on the membrane expression of these NK cell ligands in H1339 with high and MDA-MB-231 tumor cells with low basal HIF-1α levels and its consequences on NK cell-mediated cytotoxicity. We could show that a hypoxia-induced decrease in the membrane expression of MICA/B and Hsp70 on H1339 and MDA-MB-231 cells, respectively, is associated with a reduced sensitivity to NK cell-mediated lysis. A knockdown of HIF-1α revealed that the decreased surface expression of MICA/B under hypoxia is dependent on HIF-1α in H1339 cells with high basal HIF-1α levels. Hypoxia and HIF-1α did not affect the MICA/B expression in MDA-MB-231 cells but reduced the Hsp70 membrane expression which in turn also impaired NK cell recognition. Furthermore, we could show that the hypoxia-induced decrease in membrane Hsp70 is independent of HIF-1α in MDA-MB-231. Our data indicate that hypoxia-induced downregulation of both NK cell ligands MICA/B and Hsp70 impairs NK cell-mediated cytotoxicity, whereby only MICA/B appears to be regulated by HIF-1α. 相似文献
955.
Konrad Platzer Heinrich Sticht Stacey L. Edwards William Allen Kaitlin M. Angione Maria T. Bonati Campbell Brasington Megan T. Cho Laurie A. Demmer Tzipora Falik-Zaccai Candace N. Gamble Yorck Hellenbroich Maria Iascone Fernando Kok Sonal Mahida Hanna Mandel Thorsten Marquardt Kirsty McWalter Rami Jamra 《American journal of human genetics》2019,104(2):203-212
956.
957.
Konrad Herbst Emma Söderhjelm Ebbe Nordlander Michael Brorson 《Inorganica chimica acta》2007,360(8):2697-2703
The versatility of cuboidal Mo3S4Co clusters for the preparation of complexes with different numbers of valence shell electrons (VSE) in the cluster is described. The reaction of the geometrically incomplete cuboidal cluster salt [(η5-Cp′)3Mo3S4][pts] (pts = p-toluenesulfonate) with one molar equivalent of [Co2(CO)8] afforded almost quantitatively the electroneutral 60 VSE cluster [(η5-Cp′)3Mo3S4Co(CO)] (1), which previously has been prepared in low yield by Curtis et al. in autoclave syntheses [M.D. Curtis, U. Riaz, O.J. Curnow, J.W. Kampf, Organometallics 14 (1995) 5337]. Cluster 1 was also obtained in high yield by reaction of [(η5-Cp′)3Mo3S4][pts] with [(η5-Cp∗)Co(CO)2]. Reaction of [(η5-Cp′)3Mo3S4][pts] with two molar equivalents of [Co(I)(CO)3(PPh3)] led to a complex mixture of products, of which the electron deficient 58 VSE cluster salt [(η5-Cp′)3Mo3S4Co(I)][Co(I)3(thf)] ([2][Co(I)3(thf)]) was isolated as single crystals. In the crystal structures of 1 and [2][Co(I)3(thf)], the Co-Mo bond lengths are almost identical, indicating a delocalization of the electron deficiency in [2]+. The reduced form of [2]+, [(η5-Cp′)3Mo3S4Co(I)] (2), was prepared by oxidative substitution of the carbonyl ligand in 1 by I2. Further reactions of 1 with PPh3 and NO leading to the 60 and 61 VSE cluster complexes [(η5-Cp′)3Mo3S4Co(PPh3)] (3) and [(η5-Cp′)3Mo3S4Co(NO)] (4), respectively, enabled the preparation of Mo3S4Co clusters in altogether four different oxidation states. 相似文献
958.
Danckwardt S Kaufmann I Gentzel M Foerstner KU Gantzert AS Gehring NH Neu-Yilik G Bork P Keller W Wilm M Hentze MW Kulozik AE 《The EMBO journal》2007,26(11):2658-2669
The prothrombin (F2) 3' end formation signal is highly susceptible to thrombophilia-associated gain-of-function mutations. In its unusual architecture, the F2 3' UTR contains an upstream sequence element (USE) that compensates for weak activities of the non-canonical cleavage site and the downstream U-rich element. Here, we address the mechanism of USE function. We show that the F2 USE contains a highly conserved nonameric core sequence, which promotes 3' end formation in a position- and sequence-dependent manner. We identify proteins that specifically interact with the USE, and demonstrate their function as trans-acting factors that promote 3' end formation. Interestingly, these include the splicing factors U2AF35, U2AF65 and hnRNPI. We show that these splicing factors not only modulate 3' end formation via the USEs contained in the F2 and the complement C2 mRNAs, but also in the biocomputationally identified BCL2L2, IVNS and ACTR mRNAs, suggesting a broader functional role. These data uncover a novel mechanism that functionally links the splicing and 3' end formation machineries of multiple cellular mRNAs in an USE-dependent manner. 相似文献
959.
Kjeldsen KU Kjellerup BV Egli K Frølund B Nielsen PH Ingvorsen K 《FEMS microbiology ecology》2007,61(2):384-397
District heating systems (DHS) are extreme aqueous environments characterized by high temperatures, high pH (9.5-10.0), and low nutrient availability. Culture-independent and culture-dependent techniques showed that DHS may nevertheless harbour geno- and phenotypically diverse bacterial biofilm communities. Approximately 50% of the cells in biofilms growing on mild steel coupons in rotortorque reactors connected to the return line (40 degrees C) of a Danish DHS were detectable by FISH analysis and thus were probably metabolically active. A bacterial 16S rRNA gene clone library generated from the biofilms was dominated by proteobacterial phylotypes (closely related to known aerobic species) and by phylotypes affiliated to the anaerobic class Clostridia. Anoxic enrichment cultures derived from biofilms primarily contained 16S rRNA gene and dsrAB (encoding major subunits of dissimilatory sulfite reductase) phylotypes affiliated to the latter class. Alkalitolerant and neutrophilic anaerobic bacteria were isolated from the DHS, including novel Gram-positive and deltaproteobacterial sulfate-reducers and sulfite-reducers constituting novel Gram-positive lineages. In total, 39 distinct 16S rRNA gene phylotypes representing ten classes were identified. The detection of several alkalitolerant, sulfide-producing, and, thus, potentially biocorrosive species underlines the need to maintain a high water quality in the DHS in order to prevent the proliferation of these species. 相似文献
960.
Kreiter S Konrad T Sester M Huber C Türeci O Sahin U 《Cancer immunology, immunotherapy : CII》2007,56(10):1577-1587
Assessment of antigen-specific T-cell responses has been greatly facilitated by development of ELISPOT and intracellular cytokine flow cytometry (CFC) assays. The use of autologous antigen presenting cells transfected with in vitro transcribed RNA as stimulators allows in principle quantification of antigen-specific T-cells independent of the knowledge of the epitopes. We describe here a cytokine secretion assay that enables simultaneous assessment of both antigen-specific CD4+ as well as CD8+ T-cells directly from clinical samples without the need for generation of dendritic cells. To this aim, bulk PBMCs were electroporated with RNA encoding the antigen fused to trafficking signal sequences derived from a MHC class I molecule and used as stimulators. With human cytomegalovirus (HCMV) phosphoprotein 65 (pp65) as antigen we show that for measuring ex vivo T-cell responses in ELISPOT and CFC such stimulators are superior or at least equivalent to a pool of overlapping peptides representing the entire pp65 sequence as well as to untagged pp65 encoding RNA. This approach avoids the time consuming generation of dendritic cells as immune stimulators and, in particular when used in the context of the CFC, is robust, broadly applicable and fast. 相似文献