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21.
The coalescent with recombination is a fundamental model to describe the genealogical history of DNA sequence samples from recombining organisms. Considering recombination as a process which acts along genomes and which creates sequence segments with shared ancestry, we study the influence of single recombination events upon tree characteristics of the coalescent. We focus on properties such as tree height and tree balance and quantify analytically the changes in these quantities incurred by recombination in terms of probability distributions. We find that changes in tree topology are often relatively mild under conditions of neutral evolution, while changes in tree height are on average quite large. Our results add to a quantitative understanding of the spatial coalescent and provide the neutral reference to which the impact by other evolutionary scenarios, for instance tree distortion by selective sweeps, can be compared. 相似文献
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Dynamic changes in microbiota and mycobiota during spontaneous ‘Vino Santo Trentino’ fermentation 下载免费PDF全文
Irene Stefanini Davide Albanese Agostino Cavazza Elena Franciosi Carlotta De Filippo Claudio Donati Duccio Cavalieri 《Microbial biotechnology》2016,9(2):195-208
Vino Santo is a sweet wine produced from late harvesting and pressing of Nosiola grapes in a small, well‐defined geographical area in the Italian Alps. We used metagenomics to characterize the dynamics of microbial communities in the products of three wineries, resulting from spontaneous fermentation with almost the same timing and procedure. Comparing fermentation dynamics and grape microbial composition, we show a rapid increase in a small number of wine yeast species, with a parallel decrease in complexity. Despite the application of similar protocols, slight changes in the procedures led to significant differences in the microbiota in the three cases of fermentation: (i) fungal content of the must varied significantly in the different wineries, (ii) Pichia membranifaciens persisted in only one of the wineries, (iii) one fermentation was characterized by the balanced presence of Saccharomyces cerevisiae and Hanseniaspora osmophila during the later phases. We suggest the existence of a highly winery‐specific ‘microbial‐terroir’ contributing significantly to the final product rather than a regional ‘terroir’. Analysis of changes in abundance during fermentation showed evident correlations between different species, suggesting that fermentation is the result of a continuum of interaction between different species and physical–chemical parameters. 相似文献
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Filippo Maggi Claudia Giuliani Gelsomina Fico Massimo Ricciutelli Massimo Bramucci Luana Quassinti 《Plant biosystems》2019,153(2):325-335
Apium nodiflorum (L.) Lag. (water celery) is an hydrophytic plant forming dense submerged populations occurring along streams and rivers of Europe. In the present work we provided new insights into the phytochemistry and biology of A. nodiflorum. In particular, we studied the chemical profile of essential oil and polar extracts obtained from the flowering aerial parts of water celery growing in central Italy, together with the essential oil biological activities, namely antimicrobial, antioxidant and cytotoxicity on tumour cells. In addition, we correlated the productivity in secondary metabolites to the secreting structures through a detailed micromorphological study. The essential oil was dominated by two main chemotypes, characterized by myristicin and limonene, respectively. The oils showed significant toxicity on tumour cells, as evidenced by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, with IC50 values in the range 3.8–15.9 μg mL?1, together with inhibitory effects on Candida albicans (inhibition zones of 10–11 mm). HPLC-MS analysis showed the caffeoylquinic acids and quercetin-3-O-glucoside as the most abundant phenolic compounds. Ducts and vittae were the principal secretory structures of vegetative (leaves and stems) and reproductive (fruits) parts, respectively, storing mainly essential oil. Results of this work provide scientific evidences for the possible valorization and exploitation of water celery. 相似文献
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Roberta Piazza Filippo Micheletti Sara Condino Giada Magni Raffaella N. Berchiolli Paolo De Simone Vincenzo Ferrari Mauro Ferrari Roberto Pini Francesca Rossi 《Journal of biophotonics》2019,12(9)
The in situ laser fenestration is an interesting option for the endovascular treatment of short‐necked aneurysms with an intraoperative modification of a standard endograft. According to literature evidence, diode laser emitting in the near‐infrared wavelength (810 nm) can be successfully used to fenestrate the endograft fabric. This paper describes a three‐dimensional navigation system for the accurate targeting of the fenestration site, then reports results of an ex vivo study to assess whether the laser operative conditions, which ensure the fabric fenestration, are harmless for the biological tissue surrounding the endoprosthesis. Two hundred twenty‐five samples of human aorta, including healthy specimens and abdominal aortic aneurysm samples, were irradiated ex vivo using a 810 nm diode laser. Energy and pulse duration were varied. Irradiated tissues were fixed in formaldehyde, sectioned and subjected to histological examination. Only 7.5% of the irradiated samples exhibited a thermal damage, which was always confined to the contact point between the laser fiber tip and the aortic wall. These experiments suggest that the diode laser can be safely used for the proposed surgical application. 相似文献
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Filippo Conti Maria Cristina Valerio Joseph P. Zbilut Alessandro Giuliani 《Systems and synthetic biology》2007,1(4):161-165
A biological system, like any complex system, blends stochastic and deterministic features, displaying properties of both.
In a certain sense, this blend is exactly what we perceive as the “essence of complexity” given we tend to consider as non-complex
both an ideal gas (fully stochastic and understandable at the statistical level in the thermodynamic limit of a huge number
of particles) and a frictionless pendulum (fully deterministic relative to its motion). In this commentary we make the statement
that systems biology will have a relevant impact on nowadays biology if (and only if) will be able to capture the essential
character of this blend that in our opinion is the generation of globally ordered collective modes supported by locally stochastic
atomisms. 相似文献
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Absalon S Kohl L Branche C Blisnick T Toutirais G Rusconi F Cosson J Bonhivers M Robinson D Bastin P 《PloS one》2007,2(5):e437
To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist Trypanosoma brucei possesses a single flagellum that adheres to the cell body where a specific cytoskeletal structure is localised, the flagellum attachment zone (FAZ). Trypanosomes build a new flagellum whose distal tip is connected to the side of the old flagellum by a discrete structure, the flagella connector. During this process, the basal body of the new flagellum migrates towards the posterior end of the cell. We show that separate inhibition of flagellum assembly, base-to-tip motility or flagella connection leads to reduced basal body migration, demonstrating that the flagellum contributes to its own positioning. We propose a model where pressure applied by movements of the growing new flagellum on the flagella connector leads to a reacting force that in turn contributes to migration of the basal body at the proximal end of the flagellum. 相似文献
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In social systems characterized by a high degree of fission-fusion dynamics, members of a large community are rarely all together, spending most of their time in smaller subgroups with flexible membership. Although fissioning into smaller subgroups is believed to reduce conflict among community members, fusions may create conflict among individuals from joining subgroups. Here, we present evidence for aggressive escalation at fusion and its mitigation by the use of embraces in wild spider monkeys (Ateles geoffroyi). Our findings provide the first systematic evidence for conflict management at fusion and may have implications for the function of human greetings. 相似文献
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