893 resultados para stages of development
Resumo:
Our objective for this study was to evaluate the influence of preindustrial and expected future atmospheric CO2 concentrations (280 µatm and 700 µatm pCO2, respectively) on different life-cycle stages of the kelp Laminaria hyperborea from Helgoland (Germany, North Sea). Zoospore germination, gametogenesis, vegetative growth, sorus formation and photosynthetic performance of vegetative and fertile tissue were examined. The contribution of external carbonic anhydrase (exCA) to C-supply for net-photosynthesis (net-PS) and the Chla- and phlorotannin content were investigated. Female gametogenesis and vegetative growth of sporophytes were significantly enhanced under the expected future pCO2. rETR(max) and net-PS of young vegetative sporophytes tended to increase performance at higher pCO2. The trend towards elevated net-PS vanished after inhibition of exCA. In vegetative sporophytes, phlorotannin content and Chla content were not significantly affected by pCO2.
Resumo:
Ocean acidification (OA) effects on larvae are partially attributed for the rapidly declining oyster production in the Pacific Northwest region of the United States. This OA effect is a serious concern in SE Asia, which produces >80% of the world's oysters. Because climate-related stressors rarely act alone, we need to consider OA effects on oysters in combination with warming and reduced salinity. Here, the interactive effects of these three climate-related stressors on the larval growth of the Pacific oyster, Crassostrea gigas, were examined. Larvae were cultured in combinations of temperature (24 and 30 °C), pH (8.1 and 7.4), and salinity (15 psu and 25 psu) for 58 days to the early juvenile stage. Decreased pH (pH 7.4), elevated temperature (30 °C), and reduced salinity (15 psu) significantly delayed pre- and post-settlement growth. Elevated temperature lowered the larval lipid index, a proxy for physiological quality, and negated the negative effects of decreased pH on attachment and metamorphosis only in a salinity of 25 psu. The negative effects of multiple stressors on larval metamorphosis were not due to reduced size or depleted lipid reserves at the time of metamorphosis. Our results supported the hypothesis that the C. gigas larvae are vulnerable to the interactions of OA with reduced salinity and warming in Yellow Sea coastal waters now and in the future.
Resumo:
Ocean Acidification (OA) has been shown to affect photosynthesis and calcification in the coccolithophore Emiliania huxleyi, a cosmopolitan calcifier that significantly contributes to the regulation of the biological carbon pumps. Its non-calcifying, haploid life-cycle stage was found to be relatively unaffected by OA with respect to biomass production. Deeper insights into physiological key processes and their dependence on environmental factors are lacking, but are required to understand and possibly estimate the dynamics of carbon cycling in present and future oceans. Therefore, calcifying diploid and non-calcifying haploid cells were acclimated to present and future CO2 partial pressures (pCO2; 38.5 Pa vs. 101.3 Pa CO2) under low and high light (50 vs. 300 µmol photons/m**2 /s). Comparative microarray-based transcriptome profiling was used to screen for the underlying cellular processes and allowed to follow up interpretations derived from physiological data. In the diplont, the observed increases in biomass production under OA are likely caused by stimulated production of glycoconjugates and lipids. The observed lowered calcification under OA can be attributed to impaired signal-transduction and ion-transport. The haplont utilizes distinct genes and metabolic pathways, reflecting the stage-specific usage of certain portions of the genome. With respect to functionality and energy-dependence, however, the transcriptomic OA-responses resemble those of the diplont. In both life-cycle stages, OA affects the cellular redox-state as a master regulator and thereby causes a metabolic shift from oxidative towards reductive pathways, which involves a reconstellation of carbon flux networks within and across compartments. Whereas signal transduction and ion-homeostasis appear equally OA-sensitive under both light intensities, the effects on carbon metabolism and light physiology are clearly modulated by light availability. These interactive effects can be attributed to the influence of OA and light on the redox equilibria of NAD and NADP, which function as major sensors for energization and stress. This generic mode of action of OA may therefore provoke similar cell-physiological responses in other protists.
Resumo:
This article is the introduction to a special issue of The Developing Economies which presented the results of a research project by the Institute of Developing Economies that examined the development mechanisms in Korea and Taiwan. Our conclusion in this article is that their development mechanisms, despite their similar development patterns of export-led industrialization, have been essentially different: a government-led mechanism in Korea as opposed to a market-led mechanism in Taiwan. We verified this difference through comparative studies of the two economies covering trade balances, the growth of total factor productivity, the scale of enterprises and business groups, and the development processes of individual manufacturing sectors. In our explanatory discussion we propose that the difference in the mechanisms is based on: 1) the amount of accumulation in the economy at the time postwar industrialization started, 2) the relationship between government and society, and 3) the mechanism of social network formation.
Resumo:
As the success of East Asian countries has shown, labor-intensive industry is recognized to lead economic growth in the early stages of development, utilizing relatively low labor costs. This same growth process has already started in South and South East Asian LDCs since the mid-1990s. However, the manufacturing sector in sub-Saharan Africa has been underdeveloped and manufacturing exports, in particular labour-intensive goods, have stagnated. This paper investigates the international competitiveness of the African manufacturing sector and its determinants through an analytical survey of empirical studies and a comparison with Asian low income countries. Empirical evidences indicate that primary factors of competitiveness, namely productivity, labour cost and exchange rate are unfavorable in sub-Saharan Africa. Representative arguments attribute the weak competitiveness to problems in the business environment, factor endowment, and the exchange rate. However, careful review shows that labour cost is beyond the range explained by endowment and misalignment of exchange rates have been reduced in Africa. Moreover, comparison with Asian low income countries which have competitiveness in labour-intensive goods shows no difference in the quality of business environment, while the labour cost is significantly lower than sub-Saharan African countries. Although results should be considered tentative, high labour cost beyond endowment and conservative investment behavior emerge as important factors for the weak competitiveness in sub-Saharan Africa when controlling income level.
Resumo:
The World Bank's legal and judicial reforms programs have expanded considerably since it began to address the issue of governance in the early 1990s. Initially the Bank focused on legal reforms for inducing private investment. Currently, its legal assistance extends to include the criminal justice sector. Such activities cannot be directly construed from its Articles of Agreement. This paper will discuss how the Bank interpreted its Articles in order to ligitimize its expanding activities. The Bank has manoeuvred itself into the criminal justice sector by skillfully changing its concept of development without deviating from its mandate. The change can be described as an 'evolution' which has allowed the Bank to identify any area as target for its development assistance.