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Migration Potential (migration + potential)
Selected AbstractsSeed Dispersal Distances and Plant Migration Potential in Tropical East AsiaBIOTROPICA, Issue 5 2009Article first published online: 9 MAR 200, Richard T. Corlett ABSTRACT Most predictions of vegetation responses to anthropogenic climate change over the next 100 yr are based on plant physiological tolerances and do not account for the ability of plant species to migrate over the distances required in the time available, or the impact of habitat fragmentation on this ability. This review assesses the maximum routine dispersal distances achievable in tropical East Asia and their vulnerability to human impacts. Estimates for various plant,vector combinations range from < 10 m, for species dispersed by ants or mechanical means, to > 10 km for some species dispersed by wind (tiny seeds), water, fruit pigeons, large fruit bats (tiny seeds), elephants, rhinoceroses, and people. Most plant species probably have maximum dispersal distances in the 100,1000 m range, but the widespread, canopy-dominant Dipterocarpaceae and Fagaceae are normally dispersed < 100 m. Large fruit bats and fruit pigeons are particularly important for long-distance dispersal in fragmented landscapes and should be protected from hunting. The maximum seed dispersal distances estimated in this study are potentially sufficient for many plant species to track temperature changes in steep topography, but are far too small for a significant role in mitigating climate change impacts in the lowlands, where temperature and rainfall gradients are much more shallow. [source] Climate change effects on physiology and population processes of hosts and vectors that influence the spread of hemipteran-borne plant virusesGLOBAL CHANGE BIOLOGY, Issue 8 2009TOMÁS CANTO Abstract Plant virus diseases constitute one of the limiting factors to the productivity of agriculture. Changes in host plants and insect vector populations that might result from climate change (their geographical distribution range, their densities, migration potential and phenology) could affect the spread of plant viruses. At the individual level, alterations in plant physiological processes that are relevant to their molecular interactions with viruses, like changes in metabolism, leaf temperature, and their effects on some processes, like the temperature-sensitive antiviral resistance based in RNA silencing, can also influence the ability of individual plants to control viral infections. In order to assess the impact that climate change may have on the incidence and spread of hemipteran-borne plant viruses, its potential effects on virus/plant interactions and hemipteran insect vectors, as well as other operating processes, which could exacerbate or mitigate them, are identified and analyzed in this review. [source] Emerging functions of p21-activated kinases in human cancer cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2002Rakesh Kumar The p21 activated kinases (Paks), an evolutionarily conserved family of serine/threonine kinases, are important for a variety of cellular functions including cell morphogenesis, motility, survival, mitosis, and angiogenesis. Paks are widely expressed in numerous tissues and are activated by growth factors and extracellular signals through GTPase-dependent and -independent mechanisms. Overexpression of Paks in epithelial cancer cells has been shown to increase migration potential, increase anchorage independent growth, and cause abnormalities in mitosis. Dysregulation of Paks has been reported in several human tumors and neurodegenerative diseases. A growing list of novel Pak interacting proteins has opened up exciting avenues of investigation by which to understand the functions of Paks in tumorigenesis. In this review, we will summarize the current knowledge of the Paks family with respect to emerging cellular functions and possible contributions to cancer. © 2002 Wiley-Liss, Inc. [source] The effect of skeletal maturity on the regenerative function of intrinsic ACL cellsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2010Ashley N. Mastrangelo Abstract Anterior cruciate ligament (ACL) injuries are an important clinical problem, particularly for adolescent patients. The effect of skeletal maturity on the potential for ACL healing is as yet unknown. In this study, we hypothesized that fibroblastic cells from the ACLs of skeletally immature animals would proliferate and migrate more quickly than cells from adolescent and adult animals. ACL tissue from skeletally immature, adolescent, and adult pigs and sheep were obtained and cells obtained using explant culture. Cell proliferation within a collagen,platelet scaffold was measured at days 2, 7, and 14 of culture using AM MTT assay. Cellular migration was measured at 4 and 24 h using a modified Boyden chamber assay, and cell outgrowth from the explants also measured at 1 week. ACL cells from skeletally immature animals had higher proliferation between 7 and 14 days (p,<,0.01 for all comparisons) and higher migration potential at all time points in both species (p,<,0.01 for all comparisons). ACL cells from skeletally immature animals have greater cellular proliferation and migration potential than cells from adolescent or adult animals. These experiments suggest that skeletal maturity may influence the biologic repair capacity of intrinsic ACL cells. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:644,651, 2010 [source] Influence of a Self-Assembling Peptide, RADA16, Compared with Collagen I and Matrigel on the Malignant Phenotype of Human Breast-Cancer Cells in 3D Cultures and in vivoMACROMOLECULAR BIOSCIENCE, Issue 5 2009Kun Mi Abstract Cancer-cell phenotype is not only the result of malignant progression, but also dependent on the microenvironment surrounding them, including influences from the extracellular matrix and its structural properties. We have investigated the influence of the nanofiber matrix of the self-assembling peptide, RADA16, in comparison with collagen I and Matrigel on the malignant phenotype of the human breast-cancer cell, MDA-MB-231, in 3D cultures, including the morphology, survival, proliferation rate, migration potential and the effect of these matrices on the malignancy of the cancer cells in vivo. Our data indicate that these tumor cells change their morphology in response to the different 3D matrix in vitro cultures and the RADA16 self-assembling peptide scaffold mimics an extracellular matrix and could effectively reduce the malignant phenotype of the tumor cells in vitro and in vivo. [source] R-Ras promotes tumor growth of cervical epithelial cellsCANCER, Issue 3 2003Héctor Rincón-Arano B.S. Abstract BACKGROUND R-Ras is 55% identical to H-Ras. However, these two oncogenes seem to have different tumor-transforming potential. R-Ras induced cell transformation in fibroblasts but not in other cell types. R-Ras also reportedly induces a more invasive phenotype in breast epithelial cells through integrin activation. The authors studied the mechanisms whereby R-Ras induces a malignant phenotype. METHODS Dominant negative (R-Ras43N) and constitutively active (R-Ras87L) mutants of R-Ras were stably transfected into human cervical epithelium C33A cells. Transfected cells were analyzed for adhesion, cell spreading, migration, and growth in culture and in nude mice. The activity of extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI 3-K) also was determined by Western blot analysis and by in vitro kinase assays. RESULTS R-Ras87L-transfected cells, but not R-Ras43 N-transfected cells, had a higher growth rate in nude mice and in culture compared with control cells. None of the transfected C33A cells showed an increase in cell adhesion to fibronectin or collagen I, nor did they show an increment of ,1 integrin affinity. However, cells that expressed R-Ras87L, but not cells that expressed R-Ras 43N, presented a marked increase in cell spreading and migration through collagen-coated membranes. Increases in cell proliferation, spreading, and migration induced by R-Ras87L were inhibited by the PI 3-K inhibitor LY294002. In addition, PI 3-K activity, but not ERK activity, was increased only in cells that expressed R-Ras87L. CONCLUSIONS These data suggest that the oncogene R-Ras promotes tumor growth of cervical epithelial cells and increases their migration potential over collagen through a pathway that involves PI 3-K. Cancer 2003;97:575,85. © 2003 American Cancer Society. DOI 10.1002/cncr.11093 [source] Forecasting migration of cereal aphids (Hemiptera: Aphididae) in autumn and springJOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2009A. M. Klueken Abstract The migration of cereal aphids and the time of their arrival on winter cereal crops in autumn and spring are of particular importance for plant disease (e.g. barley yellow dwarf virus infection) and related yield losses. In order to identify days with migration potentials in autumn and spring, suction trap data from 29 and 45 case studies (locations and years), respectively, were set-off against meteorological parameters, focusing on the early immigration periods in autumn (22 September to 1 November) and spring (1 May to 9 June). The number of cereal aphids caught in a suction trap increased with increasing temperature, global radiation and duration of sunshine and decreased with increasing precipitation, relative humidity and wind speed. According to linear regression analyses, the temperature, global radiation and wind speed were most frequently and significantly associated with migration, suggesting that they have a major impact on flight activity. For subsequent model development, suction trap catches from different case studies were pooled and binarily classified as days with or without migration as defined by a certain number of migrating cereal aphids. Linear discriminant analyses of several predictor variables (assessed during light hours of a given day) were then performed based on the binary response variables. Three models were used to predict days with suction trap catches ,1, ,4 or ,10 migrating cereal aphids in autumn. Due to the predominance of Rhopalosiphum padi individuals (99.3% of total cereal aphid catch), no distinction between species (R. padi and Sitobion avenae) was made in autumn. As the suction trap catches were lower and species dominance changed in spring, three further models were developed for analysis of all cereal aphid species, R. padi only, and Metopolophium dirhodum and S. avenae combined in spring. The empirical, cross-classification and receiver operating characteristic analyses performed for model validation showed different levels of prediction accuracy. Additional datasets selected at random before model construction and parameterization showed that predictions by the six migration models were 33,81% correct. The models are useful for determining when to start field evaluations. Furthermore, they provide information on the size of the migrating aphid population and, thus, on the importance of immigration for early aphid population development in cereal crops in a given season. [source] | ||||||||||