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排序方式: 共有347条查询结果,搜索用时 140 毫秒
1.
Zlenko Valerii A. Kotikov Ilia V. Troshin Leonid P. 《Plant Cell, Tissue and Organ Culture》2002,70(3):295-299
Petioles from in vitro grown plants of interspecific grapevine hybrids cvs `Bianca', `Podarok Magaracha' and `Intervitis Magaracha' were cultured on solid NN medium supplemented with 2,4-D and BA at various concentrations. The callus developed was cultured in liquid NN medium supplemented with 0.5 mg l–1 BA to induce formation of somatic embryos. Somatic embryos of globular and heart-stage developed in suspensions of `Podarok Magaracha' and `Intervitis Magaracha'. In contrast, `Bianca' did not undergo embryogenesis beyond globular stage. This made it necessary to perform subculture of the suspensions to HTE liquid medium supplemented with 0.2 mg l–1 BA for the development of globular embryos into heart stage. Heart-stage embryos developed into torpedo-stage after subculturing suspensions of all three cultivars to liquid HTE medium supplemented with 0.1 mg l–1 IAA and 30 mg l–1 sodium hummate. Torpedo-stage embryo suspensions were subcultured in liquid HTE medium supplemented with 0.5 mg l–1 BA, 0.5 mg l–1 GA3 and 0.5 mg l–1 GA3 + 0.2 mg l–1 BA. After 12 days of incubation, plantlets were cultured on solid M2MS medium: without growth regulators and with 0.5 mg l–1 BA. Plantlets that developed in liquid HTE media with 0.5 mg l–1 GA3 or 0.5 mg l–1 GA3 + 0.2 mg l–1 BA produced 82–90% shoots on solid M2MS medium with 0.5 mg l–1 BA after 50 days of culture. 相似文献
2.
Matheus E. Bianconi Luke T. Dunning Emma V. Curran Oriane Hidalgo Robyn F. Powell Sahr Mian Ilia J. Leitch Marjorie R. Lundgren Sophie Manzi Maria S. Vorontsova Guillaume Besnard Colin P. Osborne Jill K. Olofsson Pascal-Antoine Christin 《Proceedings. Biological sciences / The Royal Society》2020,287(1938)
C4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C4 and non-C4 populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C4 lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C4 phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C4 physiology away from its region of origin. 相似文献
3.
4.
Hong‐Mei Liu Libor Ekrt Petr Koutecky Jaume Pellicer Oriane Hidalgo Jeannine Marquardt Fatima Pustahija Atsushi Ebihara Sonja Siljak‐Yakovlev Mary Gibby Ilia Leitch Harald Schneider 《植物分类学报:英文版》2019,57(4):418-430
Recent studies investigating the evolution of genome size diversity in ferns have shown that they have a distinctive genome profile compared with other land plants. Ferns are typically characterized by possessing medium‐sized genomes, although a few lineages have evolved very large genomes. Ferns are different from other vascular plant lineages as they are the only group to show evidence for a correlation between genome size and chromosome number. In this study, we aim to explore whether the evolution of fern genome sizes is not only shaped by chromosome number changes arising from polyploidy but also by constraints on the average amount of DNA per chromosome. We selected the genus Asplenium L. as a model genus to study the question because of the unique combination of a highly conserved base chromosome number and a high frequency of polyploidy. New genome size data for Asplenium taxa were combined with existing data and analyzed within a phylogenetic framework. Genome size varied substantially between diploid species, resulting in overlapping genome sizes among diploid and tetraploid spleenworts. The observed additive pattern indicates the absence of genome downsizing following polyploidy. The genome size of diploids varied non‐randomly and we found evidence for clade‐specific trends towards larger or smaller genomes. The 578‐fold range of fern genome sizes have arisen not only from repeated cycles of polyploidy but also through clade‐specific constraints governing accumulation and/or elimination of DNA. 相似文献
5.
Sun Y Breydo L Makarava N Yang Q Bocharova OV Baskakov IV 《The Journal of biological chemistry》2007,282(12):9090-9097
Despite the ability of most proteins to form amyloid, very little is know about amyloid fibril structures and the factors that govern their stability. Using amyloid fibrils produced from full-length prion protein (PrP), we describe a reliable approach for determining both site-specific and global conformational stability of the fibrillar form. To measure site-specific stability, we produced six variants of PrP by replacing the residues at positions 88, 98, 127, 144, 196, and 230 with cysteine, labeled the new cysteines with the fluorescent dye acrylodan, and investigated their conformational status within the amyloid form in guanidine hydrochloride-induced denaturation experiments. We found that the fibrils labeled at positions 127, 144, 196, and 230 displayed cooperative unfolding and showed a very high C1/2 value similar to that observed for the global unfolding of the amyloid structure. The unfolding at residue 98 was also cooperative; however, it showed a C1/2 value substantially lower than that of global unfolding, whereas the unfolding of fibrils labeled at residue 88 was non-cooperative. These data illustrate that there are at least two independent cooperative folding domains within the amyloid structure of the full-length PrP. In addition, kinetic experiments revealed only a partial overlap between the region that constituted the fibrillar cross-beta core and the regions that were involved in nucleation. This result illustrates that separate PrP regions accounted for the nucleation and for the formation of the conformationally most stable fibrillar core. 相似文献
6.
7.
Loogväli EL Roostalu U Malyarchuk BA Derenko MV Kivisild T Metspalu E Tambets K Reidla M Tolk HV Parik J Pennarun E Laos S Lunkina A Golubenko M Barac L Pericic M Balanovsky OP Gusar V Khusnutdinova EK Stepanov V Puzyrev V Rudan P Balanovska EV Grechanina E Richard C Moisan JP Chaventré A Anagnou NP Pappa KI Michalodimitrakis EN Claustres M Gölge M Mikerezi I Usanga E Villems R 《Molecular biology and evolution》2004,21(11):2012-2021
It has been often stated that the overall pattern of human maternal lineages in Europe is largely uniform. Yet this uniformity may also result from an insufficient depth and width of the phylogenetic analysis, in particular of the predominant western Eurasian haplogroup (Hg) H that comprises nearly a half of the European mitochondrial DNA (mtDNA) pool. Making use of the coding sequence information from 267 mtDNA Hg H sequences, we have analyzed 830 mtDNA genomes, from 11 European, Near and Middle Eastern, Central Asian, and Altaian populations. In addition to the seven previously specified subhaplogroups, we define fifteen novel subclades of Hg H present in the extant human populations of western Eurasia. The refinement of the phylogenetic resolution has allowed us to resolve a large number of homoplasies in phylogenetic trees of Hg H based on the first hypervariable segment (HVS-I) of mtDNA. As many as 50 out of 125 polymorphic positions in HVS-I were found to be mutated in more than one subcluster of Hg H. The phylogeographic analysis revealed that sub-Hgs H1*, H1b, H1f, H2a, H3, H6a, H6b, and H8 demonstrate distinct phylogeographic patterns. The monophyletic subhaplogroups of Hg H provide means for further progress in the understanding of the (pre)historic movements of women in Eurasia and for the understanding of the present-day genetic diversity of western Eurasians in general. 相似文献
8.
Monocytes treated with human immunodeficiency virus Tat kill uninfected CD4(+) cells by a tumor necrosis factor-related apoptosis-induced ligand-mediated mechanism 总被引:6,自引:0,他引:6
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Yang Y Tikhonov I Ruckwardt TJ Djavani M Zapata JC Pauza CD Salvato MS 《Journal of virology》2003,77(12):6700-6708
9.
Origin and diffusion of mtDNA haplogroup X 总被引:10,自引:0,他引:10
Reidla M Kivisild T Metspalu E Kaldma K Tambets K Tolk HV Parik J Loogväli EL Derenko M Malyarchuk B Bermisheva M Zhadanov S Pennarun E Gubina M Golubenko M Damba L Fedorova S Gusar V Grechanina E Mikerezi I Moisan JP Chaventré A Khusnutdinova E Osipova L Stepanov V Voevoda M Achilli A Rengo C Rickards O De Stefano GF Papiha S Beckman L Janicijevic B Rudan P Anagnou N Michalodimitrakis E Koziel S Usanga E Geberhiwot T Herrnstadt C Howell N Torroni A Villems R 《American journal of human genetics》2003,73(5):1178-1190
A maximum parsimony tree of 21 complete mitochondrial DNA (mtDNA) sequences belonging to haplogroup X and the survey of the haplogroup-associated polymorphisms in 13,589 mtDNAs from Eurasia and Africa revealed that haplogroup X is subdivided into two major branches, here defined as “X1” and “X2.” The first is restricted to the populations of North and East Africa and the Near East, whereas X2 encompasses all X mtDNAs from Europe, western and Central Asia, Siberia, and the great majority of the Near East, as well as some North African samples. Subhaplogroup X1 diversity indicates an early coalescence time, whereas X2 has apparently undergone a more recent population expansion in Eurasia, most likely around or after the last glacial maximum. It is notable that X2 includes the two complete Native American X sequences that constitute the distinctive X2a clade, a clade that lacks close relatives in the entire Old World, including Siberia. The position of X2a in the phylogenetic tree suggests an early split from the other X2 clades, likely at the very beginning of their expansion and spread from the Near East. 相似文献
10.
The Menkes copper-translocating P-type ATPase (ATP7A; MNK) is a ubiquitous protein that regulates the absorption of copper in the gastrointestinal tract. Inside cells the protein has a dual function: it delivers copper to cuproenzymes in the Golgi compartment and effluxes excess copper. The latter property is achieved through copper-dependent vesicular trafficking of the Menkes protein to the plasma membrane of the cell. The trafficking mechanism and catalytic activity combine to facilitate absorption and intercellular transport of copper. The mechanism of catalysis and copper-dependent trafficking of the Menkes protein are the subjects of this review. Menkes disease, a systemic copper deficiency disorder, is caused by mutations in the gene encoding the Menkes protein. The effect of these mutations on the catalytic cycle and the cell biology of the Menkes protein, as well as predictions of the effect of particular mutant MNKs on observed Menkes disease symptoms will also be discussed. 相似文献