53 research outputs found
Gene phylogenies and proteinâprotein interactions: possible artifacts resulting from shared protein interaction partners
The study of gene families critically depends on the correct reconstruction of gene genealogies, as for instance in the case of transcription factor genes like Hox genes and Dlx gene families. Proteins belonging to the same family are likely to share some of the same protein interaction partners and may thus face a similar selective environment. This common selective environment can induce co-evolutionary pressures and thus can give rise to correlated rates and patterns of evolution among members of a gene family. In this study, we simulate the evolution of a family of sequences which share a set of interaction partners. Depending on the amount of sequence dedicated to proteinâprotein interaction and the relative rate parameters of sequence evolution three outcomes are possible: if the fraction of the sequence dedicated to interaction with common co-factors is low and the time since divergence is small, the trees based on sequence information tend to be correct. If the time since gene duplication is long two possible outcomes are observed in our simulations. If the rate of evolution of the interaction partner is small compared to the rate of evolution of the focal protein family, the reconstructed trees tend towards star phylogenies. As the rate of evolution of the interaction partner approaches that of the focal protein family the reconstructed phylogenies tend to be incorrectly resolved. We conclude that the genealogies of gene families can be hard to estimate, in particular if the proteins interact with a conserved set of binding partners, as is likely the case for transcription factors
Bounded fitness landscapes and the evolution of the linguistic diversity
A simple spatial computer simulation model was recently introduced to study
the evolution of the linguistic diversity. The model considers processes of
selective geographic colonization, linguistic anomalous diffusion and mutation.
In the approach, we ascribe to each language a fitness function which depends
on the number of people that speak that language. Here we extend the
aforementioned model to examine the role of saturation of the fitness on the
language dynamics. We found that the dependence of the linguistic diversity on
the area after colonization displays a power law regime with a nontrivial
exponent in very good agreement with the measured exponent associated with the
actual distribution of languages on the Earth.Comment: 10 pages, 3 figure
Nitrogen fertilization (15NH4NO3) of palisadegrass and residual effect on subsequent no-tillage corn
Human toxocariasis: contribution by Brazilian researchers
In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of SĂŁo Paulo (IMT)
Composição corporal e requisitos lĂquidos e dietĂ©ticos de macroelementos minerais de bovinos Nelore nĂŁo-castrados
Biochemical and bioactive phytonutrients changes in tissues of two cultivars of fresh-cut cassava in stick form under refrigerated storage
The aim of this study was to evaluate the effects of fresh-cut in stick form of two cassava cultivars on their biochemical and antioxidant characteristics, at two harvest times. The fresh cut cassava sticks were packaged in polypropylene, maintained at 5±1ÂșC, with 90±5% relative humidity for 12 days. The concentration of carotenoids, total soluble phenolic compounds and the activity of phenylalanine ammonia lyase and antioxidant capacity were significantly higher for the sticks of cultivar 'Amarela' cassava than for the sticks of cultivar 'Cacau'. The concentrations of carotenoids, total soluble phenolic compounds, and the activity of phenylalanine ammonia lyase and antioxidant capacity were all significantly greater when harvested at 14-month of age. There was a significant increase in the activity of phenylalanine ammonia lyase during the 12 days of storage at 5ÂșC. However, there was a decrease in total carotenoids, soluble phenolic compounds, and in the antioxidant capacity of the two cultivars
Determinação das fraçÔes protĂ©icas e de carboidratos e taxas de degradação in vitro da cana-de-açĂșcar, da cama de frango e do farelo de algodĂŁo
WATER REQUIREMENT ESTIMATE FOR THE REPRODUCTIVE PERIOD OF MANGO ORCHADS IN THE NORTHEAST OF THE STATE OF PARĂ, BRAZIL
Capim-elefante (Pennisetum purpureum Schum.), sob duas doses de nitrogĂȘnio. Consumo e produção de leite
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