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Simulated brain tumor growth dynamics using a three-dimensional cellular automaton 总被引:10,自引:0,他引:10
Kansal AR Torquato S Harsh GR IV Chiocca EA Deisboeck TS 《Journal of theoretical biology》2000,203(4):367-382
We have developed a novel and versatile three-dimensional cellular automaton model of brain tumor growth. We show that macroscopic tumor behavior can be realistically modeled using microscopic parameters. Using only four parameters, this model simulates Gompertzian growth for a tumor growing over nearly three orders of magnitude in radius. It also predicts the composition and dynamics of the tumor at selected time points in agreement with medical literature. We also demonstrate the flexibility of the model by showing the emergence, and eventual dominance, of a second tumor clone with a different genotype. The model incorporates several important and novel features, both in the rules governing the model and in the underlying structure of the model. Among these are a new definition of how to model proliferative and non-proliferative cells, an isotropic lattice, and an adaptive grid lattice. 相似文献
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PHILIP W. ATKINSON ALLAN J. BAKER KAREN A. BENNETT NIGEL A. CLARK JACQUIE A. CLARK KIMBERLY B. COLE ANNE DEKINGA AMANDA DEY SIMON GILLINGS PATRICIA M. GONZÁLEZ KEVIN KALASZ CLIVE D. T. MINTON JASON NEWTON LAWRENCE J. NILES THEUNIS PIERSMA ROBERT A. ROBINSON HUMPHREY P. SITTERS 《Journal of Applied Ecology》2007,44(4):885-895
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PIERRE‐OLIVIER ANTOINE KEVIN F. DOWNING JEAN‐YVES CROCHET FRANCIS DURANTHON LAWRENCE J. FLYNN LAURENT MARIVAUX GRÉGOIRE MÉTAIS ABDUL RAHIM RAJPAR GHAZALA ROOHI 《Zoological Journal of the Linnean Society》2010,160(1):139-194
Rhinocerotids are particularly abundant and diversified in Neogene deposits of the Indian subcontinent, but their systematics is far from being well defined. Based on the revision of old collections and new findings from the Early Miocene of the Bugti Hills and Zinda Pir, Pakistan, ‘Aceratherium blanfordi Lydekker, 1884’ is a chimera, consisting of two dentally convergent but postcranially distinct rhinocerotid taxa: Pleuroceros blanfordi and Mesaceratherium welcommi sp. nov. Postcranial features appear to be much more diagnostic than craniodental morphology in this case. A phylogenetic analysis based on 282 morphological characters scored for 28 taxa (four outgroups and ingroup including both taxa of interest and a ‘branching group’) strengthens this statement and supports Pleuroceros and Mesaceratherium as monophyletic genera within Rhinocerotinae. Both genera are recognized for the first time outside Europe. In the Bugti Hills, P. blanfordi and M. welcommi are part of an exceptionally diversified rhinocerotid fauna, with up to nine species associated in the same locality (Kumbi 4f). This rhinocerotid assemblage confirms the earliest Miocene age (Agenian/Aquitanian) of the upper member of the Chitarwata Formation as a whole. Coeval homotaxic rhinocerotid faunas from Europe (France, Czech Republic) and East Africa (Uganda, Kenya) support broad and sustainable rhinocerotid interchanges amongst South Asia, Europe, and Africa under compatible environmental conditions throughout earliest Miocene times. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 139–194. 相似文献
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Calanus finmarchicus is a key‐structural species of the North Atlantic polar biome. The species plays an important trophic role in subpolar and polar ecosystems as a grazer of phytoplankton and as a prey for higher trophic levels such as the larval stages of many fish species. Here, we used a recently developed ecological niche model to assess the ecological niche (sensu Hutchinson) of C. finmarchicus and characterize its spatial distribution. This model explained about 65% of the total variance of the observed spatial distribution inferred from an independent dataset (data of the continuous plankton recorder survey). Comparisons with other types of models (structured population and ecophysiological models) revealed a clear similarity between modeled spatial distributions at the scale of the North Atlantic. Contemporary models coupled with future projections indicated a progressive reduction of the spatial habitat of the species at the southern edge and a more pronounced one in the Georges Bank, the Scotian Shelf and the North Sea and a potential increase in abundance at the northern edge of its spatial distribution, especially in the Barents Sea. These major changes will probably lead to a major alteration of the trophodynamics of North Atlantic ecosystems affecting the trophodynamics and the biological carbon pump. 相似文献
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Background
Since the first fungal genome sequences became available, investigators have been employing comparative genomics to understand how fungi have evolved to occupy diverse ecological niches. The secretome, i.e. the entirety of all proteins secreted by an organism, is of particular importance, as by these proteins fungi acquire nutrients and communicate with their surroundings.Results
It is generally assumed that fungi with similar nutritional lifestyles have similar secretome compositions. In this study, we test this hypothesis by annotating and comparing the soluble secretomes, defined as the sets of proteins containing classical signal peptides but lacking transmembrane domains of fungi representing a broad diversity of nutritional lifestyles. Secretome size correlates with phylogeny and to a lesser extent with lifestyle. Plant pathogens and saprophytes have larger secretomes than animal pathogens. Small secreted cysteine-rich proteins (SSCPs), which may comprise many effectors important for the interaction of plant pathogens with their hosts, are defined here to have a mature length of ≤ 300 aa residues, at least four cysteines, and a total cysteine content of ≥5%. SSCPs are found enriched in the secretomes of the Pezizomycotina and Basidiomycota in comparison to Saccharomycotina. Relative SSCP content is noticeably higher in plant pathogens than in animal pathogens, while saprophytes were in between and closer to plant pathogens. Expansions and contractions of gene families and in the number of occurrences of functional domains are largely lineage specific, e.g. contraction of glycoside hydrolases in Saccharomycotina, and are only weakly correlated with lifestyle. However, within a given lifestyle a few general trends exist, such as the expansion of secreted family M14 metallopeptidases and chitin-binding proteins in plant pathogenic Pezizomycotina.Conclusions
While the secretomes of fungi with similar lifestyles share certain characteristics, the expansion and contraction of gene families is largely lineage specific, and not shared among all fungi of a given lifestyle.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-722) contains supplementary material, which is available to authorized users. 相似文献10.
Patterns of distribution of morphology in the fossil recordshould be examined more rigorously to evaluate the relativeeffectiveness of alternative evolutionary models and to integratethe dimension of true evolutionary time more directly with evolutionarytheory. Grant (1972) has discussed three main problems in the detectionof character displacement: we must assume that sympatry followedallopatry, that the state in allopatry represents the static,pre-contact state, and that there are no other reasons accountingfor differences within a species in allopatric and sympatriczones. These problems can be largely avoided with suitable paleoiitologicaldata. In an example involving the coincident 10 million-year historiesof two congeneric species of Devonian trilobites, the one knowninstance of sympatry reveals marked divergent shifts in onespecies and a "mixed" reaction of convergent, divergent, andneutral shifts in the other species. The characters undergoingthese shifts are largely those which (i) serve as specific differentia,and (ii) show the most change within one of the species overits entire history. This suggests that character displacementmay be simply a magnified microcosm of a general pattern ofinteraction between two species even when allopatric, providedthat allopatry is sustained through competitive exclusion. 相似文献