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Isolation of a gene from Drosophila by complementation in yeast 总被引:21,自引:0,他引:21
Transformation of mutant yeast cells by cloned genomic DNA from a higher eukaryote has made it possible to isolate a Drosophila DNA sequence that complements a yeast adenine-8-mutation. A 0.8-kilobase poly(A)-containing RNA is transcribed from the cloned Drosophila segment in transformed yeast cells and can account for functional expression of the gene. 相似文献
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Poly rG can form four-stranded helices. The Hoogsteen-paired quartets of G residues on which such structures depend are so stable that they will form in 5'-GMP solutions, provided that Na+ or K+ are present (see for example, refs 2-4). Telomeric DNA sequences, which are G-rich, adopt four-stranded antiparallel G-quartet conformations in vitro, and parallel tetramerization of G-rich sequences may be involved in meiosis. Here we show that RNAs containing short runs of Gs can also tetramerize. A 19-base oligonucleotide derived from the 5S RNA of Escherichia coli (strand III), 5'GCCGAUGGUAGUGUGGGGU3', forms a K(+)-stabilized tetrameric aggregate that depends on the G residues at its 3' end. This complex is so stable that it would be surprising if similar structures do not occur in nature. 相似文献
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Topological domains in mammalian genomes identified by analysis of chromatin interactions 总被引:1,自引:0,他引:1
The spatial organization of the genome is intimately linked to its biological function, yet our understanding of higher order genomic structure is coarse, fragmented and incomplete. In the nucleus of eukaryotic cells, interphase chromosomes occupy distinct chromosome territories, and numerous models have been proposed for how chromosomes fold within chromosome territories. These models, however, provide only few mechanistic details about the relationship between higher order chromatin structure and genome function. Recent advances in genomic technologies have led to rapid advances in the study of three-dimensional genome organization. In particular, Hi-C has been introduced as a method for identifying higher order chromatin interactions genome wide. Here we investigate the three-dimensional organization of the human and mouse genomes in embryonic stem cells and terminally differentiated cell types at unprecedented resolution. We identify large, megabase-sized local chromatin interaction domains, which we term 'topological domains', as a pervasive structural feature of the genome organization. These domains correlate with regions of the genome that constrain the spread of heterochromatin. The domains are stable across different cell types and highly conserved across species, indicating that topological domains are an inherent property of mammalian genomes. Finally, we find that the boundaries of topological domains are enriched for the insulator binding protein CTCF, housekeeping genes, transfer RNAs and short interspersed element (SINE) retrotransposons, indicating that these factors may have a role in establishing the topological domain structure of the genome. 相似文献
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Coste B Xiao B Santos JS Syeda R Grandl J Spencer KS Kim SE Schmidt M Mathur J Dubin AE Montal M Patapoutian A 《Nature》2012,483(7388):176-181
Mechanotransduction has an important role in physiology. Biological processes including sensing touch and sound waves require as-yet-unidentified cation channels that detect pressure. Mouse Piezo1 (MmPiezo1) and MmPiezo2 (also called Fam38a and Fam38b, respectively) induce mechanically activated cationic currents in cells; however, it is unknown whether Piezo proteins are pore-forming ion channels or modulate ion channels. Here we show that Drosophila melanogaster Piezo (DmPiezo, also called CG8486) also induces mechanically activated currents in cells, but through channels with remarkably distinct pore properties including sensitivity to the pore blocker ruthenium red and single channel conductances. MmPiezo1 assembles as a ~1.2-million-dalton homo-oligomer, with no evidence of other proteins in this complex. Purified MmPiezo1 reconstituted into asymmetric lipid bilayers and liposomes forms ruthenium-red-sensitive ion channels. These data demonstrate that Piezo proteins are an evolutionarily conserved ion channel family involved in mechanotransduction. 相似文献
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