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排序方式: 共有487条查询结果,搜索用时 171 毫秒
1.
V. D. Lakhno A. S. Shigaev T. B. Feldman V. A. Nadtochenko M. A. Ostrovsky 《Doklady. Biochemistry and biophysics》2016,471(1):435-439
A quantum-classical model of photoisomerization of the visual pigment rhodopsin chromophore is proposed. At certain (and more realistic) parameter value combinations, the model is shown to accurately reproduce a number of independent experimental data on the photoreaction dynamics: the quantum yield, the time to reach the point of conical intersection of potential energy surfaces, the termination time of the evolution of quantum subsystem, as well as the characteristic low frequencies of retinal molecular lattice fluctuations during photoisomerization. In addition, the model behavior is in good accordance with experimental data about coherence and local character of quantum transition. 相似文献
2.
K. M. Serova A. E. Vishnyakov O. V. Zaitseva O. N. Kotenko A. N. Ostrovsky 《Doklady biological sciences》2017,475(1):144-147
The nervous system structure was compared for the first time in avicularia and vibracula in seven species of the cheilostome bryozoans from six families by immunohistochemical methods and confocal scanning microscopy. Regardless of significant differences in heterozooid shape, size, and position in a colony, their muscular and nervous systems have a common structure, which suggests their parallel evolution. 相似文献
3.
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
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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
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Biology Bulletin - A review of our own data and published material on the screening pigments of the eyes of vertebrates and invertebrates and the human eye, i.e., melanosomes and ommochromes, is... 相似文献
8.
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
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Tatiana B. Feldman Oleksandr I. Ivankov Alexander I. Kuklin Tatiana N. Murugova Marina A. Yakovleva Olga A. Smitienko Irina B. Kolchugina Adam Round Valentin I. Gordeliy Alexander V. Belushkin Mikhail A. Ostrovsky 《生物化学与生物物理学报:生物膜》2019,1861(10):183000
The supramolecular organization of the visual pigment rhodopsin in the photoreceptor membrane remains contentious. Specifically, whether this G protein-coupled receptor functions as a monomer or dimer remains unknown, as does the presence or absence of ordered packing of rhodopsin molecules in the photoreceptor membrane. Completely opposite opinions have been expressed on both issues. Herein, using small-angle neutron and X-ray scattering approaches, we performed a comparative analysis of the structural characteristics of the photoreceptor membrane samples in buffer, both in the outer segment of photoreceptor cells, and in the free photoreceptor disks. The average distance between the centers of two neighboring rhodopsin molecules was found to be ~5.8 nm in both cases. The results indicate an unusually high packing density of rhodopsin molecules in the photoreceptor membrane, but molecules appear to be randomly distributed in the membrane without any regular ordering. 相似文献