共查询到20条相似文献,搜索用时 0 毫秒
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Molecular and Cellular Biochemistry - 相似文献
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Joulain D 《化学与生物多样性》2008,5(6):896-909
For a long time, exotic scents from the islands of the South Pacific have universally been appreciated. Most frequently, fragrant flowers (e.g., frangipani, jasmine sambac, tiaré, pua kenikeni) are used locally for ornamental purposes such as flower garlands (leis). Despite their powerful and delightful fragrance, very few of these flowers have been commercially employed in this part of the world for perfume manufacturing. Creative perfumers are nevertheless strongly interested to better understand these fragrances and to use them, either genuine or artificially reconstituted. Analytical results on the fragrance of these flowers are reported, together with some economical considerations. 相似文献
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近年来的研究表明 :CpG特征结构是脊椎动物免疫系统识别微生物DNA并产生针对抗原的保护性免疫反应的主要机制 ,它在体内及体外均能诱导以Th1细胞为主的高水平、高特异性的细胞免疫应答 ;是质粒DNA疫苗及裸DNA疫苗诱导机体免疫应答的原因之一 ,在临床实验中CpG ODN已被用作抗原疫苗、DNA疫苗治疗肿瘤、变态反应性疾病的强有力佐剂。CpG特征结构能够诱导机体产生以Th1细胞为主的细胞免疫应答是因为它能够作用于T细胞、B细胞、NK细胞、巨噬细胞及树突状细胞等免疫细胞。树突状细胞是机体最主要的专职抗原呈递… 相似文献
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Complex brains have evolved a highly efficient network architecture whose structural connectivity is capable of generating a large repertoire of functional states. We detect characteristic network building blocks (structural and functional motifs) in neuroanatomical data sets and identify a small set of structural motifs that occur in significantly increased numbers. Our analysis suggests the hypothesis that brain networks maximize both the number and the diversity of functional motifs, while the repertoire of structural motifs remains small. Using functional motif number as a cost function in an optimization algorithm, we obtain network topologies that resemble real brain networks across a broad spectrum of structural measures, including small-world attributes. These results are consistent with the hypothesis that highly evolved neural architectures are organized to maximize functional repertoires and to support highly efficient integration of information. 相似文献
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生物序列motif的识别是后基因组时代的一个核心问题。本文首先回顾了识别motif的几种主要算法,然后根据motif的重要性和随机性介绍了利用网络识别motif的两种具有代表性的方法:一种是建立一个随机网络混合模型,利用EM算法识别其中随机的网络motif;另一种用修正的参数流算法过滤出其中的最大密度予图,即为生物序列motif,并指出这两种方法的优劣,最后还对今后研究方向给出了讨论。 相似文献
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Repeat elements are important components of eukaryotic genomes. One limitation in our understanding of repeat elements is that most analyses rely on reference genomes that are incomplete and often contain missing data in highly repetitive regions that are difficult to assemble. To overcome this problem we develop a new method, REPdenovo, which assembles repeat sequences directly from raw shotgun sequencing data. REPdenovo can construct various types of repeats that are highly repetitive and have low sequence divergence within copies. We show that REPdenovo is substantially better than existing methods both in terms of the number and the completeness of the repeat sequences that it recovers. The key advantage of REPdenovo is that it can reconstruct long repeats from sequence reads. We apply the method to human data and discover a number of potentially new repeats sequences that have been missed by previous repeat annotations. Many of these sequences are incorporated into various parasite genomes, possibly because the filtering process for host DNA involved in the sequencing of the parasite genomes failed to exclude the host derived repeat sequences. REPdenovo is a new powerful computational tool for annotating genomes and for addressing questions regarding the evolution of repeat families. The software tool, REPdenovo, is available for download at https://github.com/Reedwarbler/REPdenovo. 相似文献
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Shun K. Hirota Kozue Nitta Yoshihisa Suyama Nobumitsu Kawakubo Akiko A. Yasumoto Tetsukazu Yahara 《PloS one》2013,8(12)
To trace the fate of individual pollen grains through pollination processes, we determined genotypes of single pollen grains deposited on Hemerocallis stigmas in an experimental mixed-species array. Hemerocallis fulva, pollinated by butterflies, has diurnal, reddish and unscented flowers, and H. citrina, pollinated by hawkmoths, has nocturnal, yellowish and sweet scent flowers. We observed pollinator visits to an experimental array of 24 H. fulva and 12 F2 hybrids between the two species (H. fulva and H. citrina) and collected stigmas after every trip bout of swallowtail butterflies or hawkmoths. We then measured selection by swallowtail butterflies or hawkmoths through male and female components of pollination success as determined by single pollen genotyping. As expected, swallowtail butterflies imposed selection on reddish color and weak scent: the number of outcross pollen grains acquired is a quadratic function of flower color with the maximum at reddish color, and the combined pollination success was maximal at weak scent (almost unrecognizable for human). This explains why H. fulva, with reddish flowers and no recognizable scent, is mainly pollinated by swallowtail butterflies. However, we found no evidence of hawkmoths-mediated selection on flower color or scent. Our findings do not support a hypothesis that yellow flower color and strong scent intensity, the distinctive floral characteristics of H. citrina, having evolved in adaptations to hawkmoths. We suggest that the key trait that triggers the evolution of nocturnal flowers is flowering time rather than flower color and scent. 相似文献
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Malde K 《Bioinformatics (Oxford, England)》2011,27(7):1041-1042
The SFF file format produced by Roche's 454 sequencing technology is a compact, binary format that contains the flow values that are used for base and quality calling of the reads. Applications, e.g. in metagenomics, often depend on accurate sequence information, and access to flow values is important to estimate the probability of errors. Unfortunately, the programs supplied by Roche for accessing this information are not publicly available. Flower is a program that can extract the information contained in SFF files, and convert it to various textual output formats. AVAILABILITY: Flower is freely available under the General Public License. 相似文献
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Summary Interactions between proteins are extremely variable. However, in the dimeric proteins comprised of regular motifs, interface interactions are similar to those that stabilize monomers. Additional stability is gained by converting loops within motifs or domains to linkers across interfaces. In multi-domain proteins, interactions can be greatly effected by the conformation of linkers between domains. Complex association of subunits, involving higher rotational symmetry or cubic symmetry, frequently involves motif sharing across interfaces. 相似文献
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Topogenic Motifs in P-type ATPases 总被引:4,自引:0,他引:4
Geering K 《The Journal of membrane biology》2000,174(3):181-190