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排序方式: 共有123条查询结果,搜索用时 15 毫秒
1.
WEICHAO Zhai DERRICK YONG JEHAN JOMAA EL-JAWHARI RICHARD CUTHBERT DENNIS MCGONAGLE MAY WIN NAING ELENA JONES 《Cytotherapy》2019,21(8):803-819
Regardless of their tissue of origin, multipotent mesenchymal stromal cells (MSCs) are commonly expanded in vitro for several population doublings to achieve a sufficient number of cells for therapy. Prolonged MSC expansion has been shown to result in phenotypical, morphological and gene expression changes in MSCs, which ultimately lead to the state of senescence. The presence of senescent cells in therapeutic MSC batches is undesirable because it reduces their viability, differentiation potential and trophic capabilities. Additionally, senescent cells acquire senescence-activated secretory phenotype, which may not only induce apoptosis in the neighboring host cells following MSC transplantation, but also trigger local inflammatory reactions. This review outlines the current and promising new methodologies for the identification of senescent cells in MSC cultures, with a particular emphasis on non-destructive and label-free methodologies. Technologies allowing identification of individual senescent cells, based on new surface markers, offer potential advantage for targeted senescent cell removal using new-generation senolytic agents, and subsequent production of therapeutic MSC batches fully devoid of senescent cells. Methods or a combination of methods that are non-destructive and label-free, for example, involving cell size and spectroscopic measurements, could be the best way forward because they do not modify the cells of interest, thus maximizing the final output of therapeutic-grade MSC cultures. The further incorporation of machine learning methods has also recently shown promise in facilitating, automating and enhancing the analysis of these measured data. 相似文献
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ELENA V. ERMILOVA ZHANNETA M. ZALUTSKAYA MAXIM M. NIKITIN TATYANA V. LAPINA EMILIO FERNÁNDEZ 《Plant, cell & environment》2010,33(6):1049-1056
The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre‐gametes mostly used a low‐affinity system (LATS) component, but gametes obtained after light treatment of N‐deprived pre‐gametes expressed both LATS and high‐affinity system (HATS) components for the uptake of methylammonium/ammonium. The activity of the LATS component was stimulated by light in only 5 min in a process independent of protein synthesis. By using the lrg6 mutant that produces sexually competent gametes in the dark, light effects on ammonium transport and gamete differentiation have been separately analysed. We have found light regulation of four Amt1 genes: Amt1; 1, Amt1; 2, Amt1; 4 and Amt1; 5. Whereas light‐dependent expression of Amt1; 1, Amt1; 2 and Amt1; 4 was independent of gametogenesis, and that of Amt1; 5 was activated in the lrg6 mutant, suggesting a connection between this transporter and the subsequent events taking place during gametogenesis. 相似文献
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ELENA V. BUZAN BORIS KRYSTUFEK BERND HÄNFLING WILLIAM F. HUTCHINSON 《Biological journal of the Linnean Society. Linnean Society of London》2008,94(4):825-835
Comprehensive taxonomic sampling can vastly improve the accuracy of phylogenetic reconstruction. Here, we present the most inclusive phylogenetic analysis of Arvicolinae (Mammalia, Rodentia) to date, combining all published cytochrome b gene sequences of greater than 1097 bp and new sequences from two monotypic genera. Overall, the phylogenetic relationships between 69 species of voles and lemmings, representing 18 genera and 10 tribes, were studied. By applying powerful modern approaches to phylogenetic reconstruction, such as maximum likelihood and Bayesian analysis, we provide new information on the early pulse of evolution within the Arvicolinae. While the position of two highly divergent lineages, Phenacomys and Ondatra , could not be resolved, the tribe Lemmini, appeared as the most basal group of voles. The collared lemmings (Dicrostonychini) grouped together with all of the remaining tribes. The two previously unstudied monotypic genera Dinaromys and Prometheomys form a moderately well-supported monophyletic clade, possibly a sister group to Ellobius (Ellobiusini). Furthermore, with one exception, all tribes ( sensu Musser & Carleton, 2005) proved to be monophyletic and can thus be regarded as meaningful evolutionary entities. Only the tribe Arvicolini emerged as paraphyletic in both analyses because of the unresolved phylogenetic position of Arvicola terrestris . Steppe voles of the genus Lagurus were solidly supported as a sister group to the Microtus and allies clade. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 825–835. 相似文献
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MARCO MASSETI ELENA PECCHIOLI CRISTIANO VERNESI 《Biological journal of the Linnean Society. Linnean Society of London》2008,93(4):835-844
The European fallow deer ( Dama dama dama ) is one of the most widespread cervids, and its distribution has been heavily affected by man. At present, only one wild autochthonous population is reputed to survive in Anatolia, but its census size is dramatically decreasing. This means that a significant portion of the ancestral genetic diversity of this taxon is seriously threatened. In the present study, a portion of the mitochondrial DNA (D-loop) in 37 D. d. dama specimens from three Mediterranean sites, Turkey, the island of Rhodes (Greece), and the Italian Peninsula, and seven individuals of the Persian fallow deer, Dama dama mesopotamica , was sequenced, and the results from the data analysis are interpreted in light of current archaeozoological and biogeographical knowledge. We conclude that: (1) D. d. mesopotamica is strongly differentiated from D. d. dama , confirming the results of previous genetic studies and (2) the Rhodian populations of D. d. dama , founded by humans in Neolithic times, possess a set of mitochondrial lineages, found in no other study populations. The persistence of these haplotypes is particularly significant because human-mediated processes (e.g. domestication) usually result in genetic depletion and erosion of an ancestral genetic pool. In the case of the Rhodes' population of fallow deer, we hypothesize that, during the foundation of this population, humans unknowingly preserved a remarkable portion of the original genetic diversity of the source population(s). © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 835–844. 相似文献
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DITTE HOLM ANDERSEN ELENA FABBRI ALBERTO SANTINI SANDRINE PAGET EDOUARD CADIEU FRANCIS GALIBERT CATHERINE ANDR ETTORE RANDI 《Molecular ecology resources》2006,6(4):1184-1187
We characterized 59 canine single nucleotide polymorphisms (SNPs) in the endangered Italian wolf (Canis lupus) population, which were discovered by resequencing sequence‐tagged‐site (STS) DNA sequences that are known to contain SNPs in domestic dogs. Dog SNPs were usually found also in wolves. Additional SNPs unique in dogs or wolves were discovered, which is important for detecting hybrids between dogs and wolves. We developed new primer sets and analysed 15 SNPs by Pyrosequencing. The characterized SNPs will provide an important addition to the genetic markers that are currently available for studying wild populations of canids. 相似文献
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SALLY HLADYZ SCOTT D. TIEGS MARK O. GESSNER PAUL S. GILLER GETA RÎŞNOVEANU ELENA PREDA MARIUS NISTORESCU MARKUS SCHINDLER GUY WOODWARD 《Freshwater Biology》2010,55(9):1916-1929
1. Human land‐use has altered catchments on a large scale in most parts of the world, with one of the most profound changes relevant for streams and rivers being the widespread clearance of woody riparian vegetation to make way for livestock grazing pasture. Increasingly, environmental legislation, such as the EU Water Framework Directive (EU WFD), calls for bioassessment tools that can detect such anthropogenic impacts on ecosystem functioning. 2. We conducted a large‐scale field experiment in 30 European streams to quantify leaf‐litter breakdown, a key ecosystem process, in streams whose riparian zones and catchments had been cleared for pasture compared with those in native deciduous woodland. The study encompassed a west–east gradient, from Ireland to Switzerland to Romania, with each of the three countries representing a distinct region. We used coarse‐mesh and fine‐mesh litter bags (10 and 0.5 mm, respectively) to assess total, microbial and, by difference, macroinvertebrate‐mediated breakdown. 3. Overall, total breakdown rates did not differ between land‐use categories, but in some regions macroinvertebrate‐mediated breakdown was higher in deciduous woodland streams, whereas microbial breakdown was higher in pasture streams. This result suggests that overall ecosystem functioning is maintained by compensatory increases in microbial activity in pasture streams. 4. We suggest that simple coefficients of breakdown rates on their own often might not be powerful enough as a bioassessment tool for detecting differences related to land‐use such as riparian vegetation removal. However, shifts in the relative contributions to breakdown by microbial decomposers versus invertebrate detritivores, as revealed by the ratios of their associated breakdown rate coefficients, showed clear responses to land‐use. 相似文献
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1. The leaf beetle, Chrysomela lapponica, originally uses the salicyl glucosides (SGs) of its host plants to sequester salicylaldehyde, which serves as a defence against generalist enemies but attracts specialist enemies. However, some populations of C. lapponica have shifted to SG‐poor hosts, and their secretions do not contain salicylaldehyde. 2. In was suggested that beetles shift to SG‐poor hosts to escape from specialist enemies. To test this hypothesis, we compared field mortality between two populations of C. lapponica that were associated with SG‐rich willow, Salix myrsinifolia (Kola Peninsula and Finland) and two populations that fed on SG‐poor willows, S. glauca (Ural) and S. caprea (Belarus). 3. Mortality from generalist enemies was significantly higher in Belarus than in three other populations, whereas mortality from specialists did not differ among populations. A specialist predator (syrphid fly larvae, Parasyrphus nigritarsis) and specialist parasitoids (phorid flies, Megaselia spp.) were attracted to the secretions of larvae reared on both SG‐rich and SG‐poor hosts. 4. Feeding on leaves of S. caprea and S. myrsinifolia both previously damaged by leaf puncturing and by the larvae of potentially competing species Chrysomela vigintipunctata, decreased the weight and prolonged the development of C. lapponica. 5. Thus, populations of C. lapponica that have shifted to SG‐poor willow species did not obtain enemy‐free space because specialist enemies have developed adaptations to herbivores that switched to a novel host plant. We suggest that in some populations host plant shift was favoured by interspecific competition with the early season SG‐using specialist, C. vigintipunctata. 相似文献