936 resultados para growth and yield


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In the last two decades, cases of corruption have been unveiled in different countries, raising public awareness and reinforcing a trend in which society expects more from their leaders. Our objective in this paper is to examine the effects of corruption and seigniorage on inflation and growth rates. The model used in this article is an extension of the model used by Huang and Wei (2006). We find interesting results and one of them is that, under some conditions, corruption has a positive impact on the growth rate. JEL classification : D73, E52, E58, E62. Keywords : Corruption; Fiscal Policy; Growth; Monetary Policy; Seigniorage.

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Zebrafish has been largely accepted as a vertebrate multidisciplinary model but its usefulness as a model for exercise physiology has been hampered by the scarce knowledge on its swimming economy, optimal swimming speeds and cost of transport. Therefore, we have performed individual and group-wise swimming experiments to quantify swimming economy and to demonstrate the exercise effects on growth in adult zebrafish.

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Prostate cancer is generally a slowly developing disease. However, some cancers develop into an aggressive, metastasic and consequently life-threatening state. The mechanisms of prostate cancer spread are still mainly unidentified but hormones and growth factors are known to been involved. The forming of new blood vessels i.e. angiogenesis is crucial for tumor growth. Blood vessels and lymphatic vessels are also prominent routes for metastasis. Both angiogenic and lymphangiogenic factors are overexpressed in prostate cancer. We established an in vivo model to study the factors effecting human prostate cancer growth and metastasis. Tumors were produced by the orthotopic inoculation of PC-3 prostate cancer cells into the prostates of immunodeficient mice. Like human prostate tumors, these tumors metastasized to prostate-draining lymph nodes. Treatment of the mice with the bisphosphonate alendronate known to decrease prostate cancer cell invasion in vitro inhibited metastasis and decreased tumor growth. Decreased tumor growth was associated with decreased angiogenesis and increased apoptosis of tumor cells. To elucidate the role of angiogenesis in prostate cancer progression, we studied the growth of orthotopic PC-3 tumors overexpressing fibroblast growth factor b (FGF8b) known to be expressed in human prostate cancer. FGF8b increased tumor growth and angiogenesis, which were both associated with a characteristic gene expression pattern. To study the role of lymphangiogenesis, we produced orthotopic PC-3 tumors overexpressing vascular endothelial growth factor C (VEGF-C). Blocking of VEGF-C receptor (VEGFR3) completely inhibited lymph node metastasis whereas overexpression of VEGF-C increased tumor growth and angiogenesis. VEGF-C also increased lung metastases but, surprisingly, decreased spread to lymph nodes. This suggests that the expanded vascular network was primarily used as a route for tumor spreading. Finally, the functionality of the capillary network in subcutaneous FGF8b-overexpressing PC-3 tumors was compared to that of tumors overexpressing VEGF. Both tumors showed angiogenic morphology and grew faster than control tumors. However, FGF8b tumors were hypoxic and their perfusion and oxygenation was poor compared with VEGF tumors. This suggests that the growth advantage of FGF8b tumors is more likely due to stimulated proliferation than effective angiogenesis. In conclusion, these results show that orthotopic prostate tumors provide a useful model to explore the mechanisms of prostate cancer growth and metastasis.

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The tomato cv. Fukuju nº. 2 was used for studying the effect of single and double infections with Potato virus X (PVX) and Tobacco mosaic virus (TMV). Mixed infection resulted in a synergistic increase of disease severity, where more growth reduction was seen with simultaneous inoculations than with sequential inoculations at four-day intervals. At five and 12 days post-inoculation, the increased severity of the disease coincided with enhancement of virus accumulation in the rapidly expanding upper leaves. The PVX concentration in leaves nº 5 to 7 of doubly infected plants was three to six fold that of singly infected ones, as determined by DAS-ELISA. Mixed infection with the L strain led to higher enhancement of PVX than with the TMV-L11A strain. The concentration of TMV-L was lower in double infection and significantly higher than TMV-L11A in both singly and doubly infected plants. Analyses of the PVX ORF2 by Western blot and Northern hybridization revealed the pattern of accumulation of the 25 kDa protein and the RNAs, respectively, following those of the virion and coat protein. The strain TMV-L11A overcame the resistance gene in cv. GCR 237 (Tm-1). In the upper leaf nº. 8, the concentration of PVX was three times higher in plants with mixed infection than with L11A. The concentrations of the L and OM (TMV strains) in both singly and doubly infected plants were at very low levels, and the synergistic effect on PVX concentration and disease severity was not observed.

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The effect of Heterodera glycines on photosynthesis, leaf area and yield of soybean (Glycine max) was studied in two experiments carried out under greenhouse condition. Soybean seeds were sown in 1.5 l (Experiment 1) or 5.0 l (Experiment 2) clay pots filled with a mixture of field soil + sand (1:1) sterilized with methyl bromide. Eight days after sowing, seedlings were thinned to one per pot, and one day later inoculated with 0; 1.200; 3.600; 10.800; 32.400 or 97.200 J2 juveniles of H. glycines. Experiment 1 was carried out during the first 45 days of the inoculation while Experiment 2 was conducted during the whole cycle of the crop. Measurements of photosynthetic rate, stomatic conductance, chlorophyll fluorescence, leaf color, leaf area, and chlorophyll leaf content were taken at ten-day intervals throughout the experiments. Data on fresh root weight, top dry weight, grain yield, number of eggs/gram of roots, and nematode reproduction factor were obtained at the end of the trials. Each treatment was replicated ten times. There was a marked reduction in both photosynthetic rate and chlorophyll content, as well as an evident yellowing of the leaves of the infected plants. Even at the lowest Pi, the effects of H. glycines on the top dry weight or grain yield were quite severe. Despite the parasitism, soybean yield was highly correlated with the integrated leaf area and, accordingly, the use of this parameter was suggested for the design of potential damage prediction models that include physiological aspects of nematode-diseased plants.

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The addition of organic residues to soil is an option to control some soil-borne diseases. Benzaldehyde and powders of kudzu (Pueraria lobata), velvetbean (Mucuna deeringiana), and pine-bark (Pinus elliottii and P. taeda) added to soil could reduce certain soil-borne diseases. This study evaluated the effects of benzaldehyde and the dried powders of kudzu, velvetbean, and pine-bark as soil amendments on germination and formation of sclerotia, on mycelial growth of Sclerotium rolfsii, on plant survival, and disease incidence. The data showed that high amounts of benzaldehyde (0.4 ml kg-1 of soil) and velvetbean (100 g kg-1) inhibited S. rolfsii mycelial growth and sclerotium germination. However, low amounts of benzaldehyde (0.1 ml kg-1), kudzu (25 g kg-1), and pine-bark (25 g kg-1) stimulated mycelial growth and sclerotium germination. Kudzu (25-100 g kg-1) and velvetbean (25-100 g kg-1) inhibited the formation of sclerotia. Nevertheless, benzaldehyde at 0.2 and 0.4 ml kg-1 stimulated the formation of sclerotia. Kudzu (50 and 100 g kg-1) and pine-bark (50 g kg-1) favored the colonization of sclerotia by Trichoderma sp. The numbers of soybean (Glycine max) plants were higher and diseased plants were lower than the non-amend soil in the following treatments: kudzu (50 and 100 g kg-1), velvetbean (50 and 100 g kg-1), and pine-bark (50 g kg-1). Disease severity on tomato (Lycopersicon esculentum) plants was low in soil treated with kudzu or velvetbean (30 and 35 g kg-1) and pine-bark (35 g kg-1). Dried powders of kudzu, velvetbean, or pine-bark added to soil can reduce disease by reducing pathogen inoculum.

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The growth of breast cancer is regulated by hormones and growth factors. Recently, aberrant fibroblast growth factor (FGF) signalling has been strongly implicated in promoting the progression of breast cancer and is thought to have a role in the development of endocrine resistant disease. FGFs mediate their auto- and paracrine signals through binding to FGF receptors 1-4 (FGFR1-4) and their isoforms. Specific targets of FGFs in breast cancer cells and the differential role of FGFRs, however, are poorly described. FGF-8 is expressed at elevated levels in breast cancer, and it has been shown to act as an angiogenic, growth promoting factor in experimental models of breast cancer. Furthermore, it plays an important role in mediating androgen effects in prostate cancer and in some breast cancer cell lines. We aimed to study testosterone (Te) and FGF-8 regulated genes in Shionogi 115 (S115) breast cancer cells, characterise FGF-8 activated intracellular signalling pathways and clarify the role of FGFR1, -2 and -3 in these cells. Thrombospondin-1 (TSP-1), an endogenous inhibitor of angiogenesis, was recognised as a Te and FGF-8 regulated gene. Te repression of TSP-1 was androgen receptor (AR)-dependent. It required de novo protein synthesis, but it was independent of FGF-8 expression. FGF-8, in turn, downregulated TSP-1 transcription by activating the ERK and PI3K pathways, and the effect could be reversed by specific kinase inhibitors. Differential FGFR1-3 action was studied by silencing each receptor by shRNA expression in S115 cells. FGFR1 expression was a prerequisite for the growth of S115 tumours, whereas FGFR2 expression alone was not able to promote tumour growth. High FGFR1 expression led to a growth advantage that was associated with strong ERK activation, increased angiogenesis and reduced apoptosis, and all of these effects could be reversed by an FGFR inhibitor. Taken together, the results of this thesis show that FGF-8 and FGFRs contribute strongly to the regulation of the growth and angiogenesis of experimental breast cancer and support the evidence for FGF-FGFR signalling as one of the major players in breast cancers.

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Four levels of shading (full sunlight (0%), 30, 50, 70% of solar radiation interception on growth, chlorophyll concentration and photosynthetic rate were studied in Croton urucurana Baill., a pioneer plant species. This species seedlings are of potential interest for reforestation projects and recovery of degraded areas. The seedlings were grown in pots containing soil and sand (2:1) and later transferred to plastic bags of 3 dm³ and submitted to different levels of shading (30, 50, 70%) of solar radiation and full sunlight, as control. The experimental design was completely randomized with five replicates and each experimental unit was composed of five plants. The results suggest that plants submitted to 70% shading showed higher dry weight accumulation in leaf and root, and higher plant height and leaf area. However, the seedlings root system showed higher dry biomass under full sunlight. It was observed a tendency to increase chlorophyll concentration and to decrease photosynthetic rate with the increase of the shading level.