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91.
Evolution and maintenance of haploid–diploid life cycles in natural populations: The case of the marine brown alga Ectocarpus 下载免费PDF全文
Lucía Couceiro Mickael Le Gac Heather M. Hunsperger Stéphane Mauger Christophe Destombe J. Mark Cock Sophia Ahmed Susana M. Coelho Myriam Valero Akira F. Peters 《Evolution; international journal of organic evolution》2015,69(7):1808-1822
The evolutionary stability of haploid–diploid life cycles is still controversial. Mathematical models indicate that niche differences between ploidy phases may be a necessary condition for the evolution and maintenance of these life cycles. Nevertheless, experimental support for this prediction remains elusive. In the present work, we explored this hypothesis in natural populations of the brown alga Ectocarpus. Consistent with the life cycle described in culture, Ectocarpus crouaniorum in NW France and E. siliculosus in SW Italy exhibited an alternation between haploid gametophytes and diploid sporophytes. Our field data invalidated, however, the long‐standing view of an isomorphic alternation of generations. Gametophytes and sporophytes displayed marked differences in size and, conforming to theoretical predictions, occupied different spatiotemporal niches. Gametophytes were found almost exclusively on the alga Scytosiphon lomentaria during spring whereas sporophytes were present year‐round on abiotic substrata. Paradoxically, E. siliculosus in NW France exhibited similar habitat usage despite the absence of alternation of ploidy phases. Diploid sporophytes grew both epilithically and epiphytically, and this mainly asexual population gained the same ecological advantage postulated for haploid–diploid populations. Consequently, an ecological interpretation of the niche differences between haploid and diploid individuals does not seem to satisfactorily explain the evolution of the Ectocarpus life cycle. 相似文献
92.
93.
Dubinectes infirmussp. n., Munnopsidae, is described from the Argentine Basin, southwest Atlantic, at depths between 4586-4607 m. The new species is distinguished by a narrow rim of the pleotelson posterior margin which is not raising over its dorsal surface; article 3 of the antennula is subequal in length to article 2; distomedial lobes of male pleopod 1 are of same size as distolateral lobes; stylet of male pleopod 2 is subequal in length to protopod; uropod exopod is more than a half of endopod length. Some generic characters which are weakly pronounced in the new species or have different state are defined more precisely in the revised diagnosis of Dubinectes. The modified diagnosis of the genus, a key to the species of Dubinectes as well as the distribution of the genus are presented. 相似文献
94.
Davis S 《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2011,42(2):226-232
Absent as a breeding bird from Britain for at least a century, avocets (Recurvirostra avosetta) began nesting on the east coast of Britain, in Suffolk, shortly after the end of the Second World War, having honed in on two spots on Britain's coast that had been flooded for war-related reasons. The avocets' presence was surrounded in secrecy, while a dedicated few kept up a protective watch over them. As the Royal Society for the Protection of Birds (RSPB) took over responsibility for the flourishing colony, they claimed the episode as a symbol of success for British protection, later making the bird their logo. Counter to the RSPB's story of protecting a British bird, I read the narratives of events in terms of making a bird British. I show how, as postwar Britain slumped economically and spiritually and tried to rebuild itself, the birds became a vehicle for formulating national identity: of Britain as a home to which to return and belong. Exploring the themes of returning servicemen and closed territories, the paper also examines the episode in terms of the naturalisation of the military and the militarisation of nature. 相似文献
95.
96.
Gustavsson E Ek S Steen J Kristensson M Älgenäs C Uhlén M Wingren C Ottosson J Hober S Borrebaeck CA 《New biotechnology》2011,28(4):302-311
In the past decade, many initiatives were taken for the development of antibodies for proteome-wide studies, as well as characterisation and validation of clinically relevant disease biomarkers. Phage display offers many advantages compared to antibody generation by immunisation because it is an unlimited resource of affinity reagents without batch-to-batch variation and is also amendable for high throughput in contrast to conventional hybridoma technology. One of the major bottlenecks to proteome-wide binder selection is the limited supply of suitable target antigens representative of the human proteome. Here, we provide proof of principle of using easily accessible, cancer-associated protein epitope signature tags (PrESTs), routinely generated within the Human Protein Atlas project, as surrogate antigens for full-length proteins in phage selections for the retrieval of target-specific binders. These binders were subsequently tested in western blot, immunohistochemistry and protein microarray application to demonstrate their functionality. 相似文献
97.
Biomarker identification is of utmost importance for the development of novel diagnostics and therapeutics. Here we make use of a translational database selection strategy, utilizing data from the Human Protein Atlas (HPA) on differentially expressed protein patterns in healthy and breast cancer tissues as a means to filter out potential biomarkers for underlying genetic causatives of the disease. DNA was isolated from ten breast cancer biopsies, and the protein coding and flanking non-coding genomic regions corresponding to the selected proteins were extracted in a multiplexed format from the samples using a single DNA sequence capture array. Deep sequencing revealed an even enrichment of the multiplexed samples and a great variation of genetic alterations in the tumors of the sampled individuals. Benefiting from the upstream filtering method, the final set of biomarker candidates could be completely verified through bidirectional Sanger sequencing, revealing a 40 percent false positive rate despite high read coverage. Of the variants encountered in translated regions, nine novel non-synonymous variations were identified and verified, two of which were present in more than one of the ten tumor samples. 相似文献
98.
Engineering bispecificity into a single albumin-binding domain 总被引:2,自引:0,他引:2
Bispecific antibodies as well as non-immunoglobulin based bispecific affinity proteins are considered to have a very high potential in future biotherapeutic applications. In this study, we report on a novel approach for generation of extremely small bispecific proteins comprised of only a single structural domain. Binding to tumor necrosis factor-α (TNF-α) was engineered into an albumin-binding domain while still retaining the original affinity for albumin, resulting in a bispecific protein composed of merely 46 amino acids. By diversification of the non albumin-binding side of the three-helix bundle domain, followed by display of the resulting library on phage particles, bispecific single-domain proteins were isolated using selections with TNF-α as target. Moreover, based on the obtained sequences from the phage selection, a second-generation library was designed in order to further increase the affinity of the bispecific candidates. Staphylococcal surface display was employed for the affinity maturation, enabling efficient isolation of improved binders as well as multiparameter-based sortings with both TNF-α and albumin as targets in the same selection cycle. Isolated variants were sequenced and the binding to albumin and TNF-α was analyzed. This analysis revealed an affinity for TNF-α below 5 nM for the strongest binders. From the multiparameter sorting that simultaneously targeted TNF-α and albumin, several bispecific candidates were isolated with high affinity to both antigens, suggesting that cell display in combination with fluorescence activated cell sorting is a suitable technology for engineering of bispecificity. To our knowledge, the new binders represent the smallest engineered bispecific proteins reported so far. Possibilities and challenges as well as potential future applications of this novel strategy are discussed. 相似文献
99.
Sophia S. Barinova Alexey Petrov Eviatar Nevo 《Central European Journal of Biology》2011,6(2):246-259
Comparative analysis of algal communities in the rivers of Israel was completed to highlight the influence of environmental
variables on biodiversity. The study revealed that 671 species of algae and cyanobacteria belonging to nine taxonomic divisions
were present during 2002–2009 in the Yarqon, Alexander, Hadera, Qishon, Oren, Lower and Upper Jordan, and Zin rivers. The
species richness of each river was evaluated by taxonomic structural comparison, geobotanical, hierarchical cluster analysis,
and the degree of relatedness for different levels of taxonomic resolution. The analysis revealed close similarity of the
Upper Jordan and Oren rivers. The average taxonomic distinctness index showed that the Yarqon, Oren, Upper Jordan, and Qishon
communities were partly degraded due to permanent environmental disturbances. The variation in taxonomic distinctness index
showed that the Alexander, Yarqon and Hadera communities were formed not only due to anthropogenic factors but also through
long-term climatic impact. The most abundant indicator species inhabit low streaming and standing alkaline waters of medium
salinity and low to medium organic pollution. The statistical approaches allowed discrimination between climatic and anthropogenic
factors that impact upon the riverine biodiversity in semi-arid environments. Analysis shows the influence of anthropogenic
factors was strongly modulated by climatic impacts causing a marked decease of species richness from north to south. 相似文献
100.
Weisberg E Ray A Nelson E Adamia S Barrett R Sattler M Zhang C Daley JF Frank D Fox E Griffin JD 《PloS one》2011,6(9):e25351