Phosphate absorption by Arabidopsis thaliana : the effects of phosphorus nutritional status : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology and Biotechnology at Massey University, Palmerston North, New Zealand

The effect of phosphorus nutritional status on phosphate uptake within the concentration range of the high affinity uptake mechanism, and subsequent translocation to the shoot was investigated in the plant species Arabidopsis thaliana. Plants of different nutritional status were generated by exposure to different set phosphate concentrations throughout an aseptic hydroponic growing period. Alternatively phosphorus deficiency was induced by growth at high concentrations of phosphate followed by a period of 5 days in phosphate-free hydroponic solution. In effect these growth conditions resulted in plants of distinguishable phenotypic character with respect to phosphate absorption, phosphate translocation, arsenate sensitivity and root-shoot ratio. To determine absorption kinetics nutrient depletion trials were carried out in which phosphate uptake was measured by monitoring the loss of phosphate from depletion solutions of set initial phosphate concentration to which the root systems of intact plants were exposed. Km and Vmax kinetic parameters were calculated from the depletion trial data using the software package "Igor Pro". Influx and net phosphate uptake was determined by setting the initial phosphate concentration of the depletion trials using either 32 P labelled KH 2 P0 4 or non-labelled KH 2 P0 4 respectively. Radioactivity was measured by counting the Cerenkov radiation in a scintillation counter. Non-labelled phosphate depletion was measured by either spectrophotometric assay or ion chromatography. To asses the effect of the phosphate analogue arsenate on phosphate influx, 32 P labelled phosphate uptake was measured with arsenate (KH 2 AsO 4 ) present in the depletion solution at a concentration of 20 µM. Phosphate translocation was determined by counting the Cerenkov radiation in the roots and shoots separately of plants that had been exposed to the 32 P labelled depletion solutions. Under the conditions of this project, phosphorus deficient plants exhibited alterations in the kinetic parameters Km and Vmax for phosphate uptake that were dependent on how the deficiency was induced. For plants that were grown continuously at low phosphate concentrations Km was decreased without a concomitant change in Vmax. For plants that were grown at high concentrations of phosphate followed by a 5 day period of phosphate starvation, a significant increase in Vmax was recorded without an associated change to Km. Phosphate uptake was found to be severely inhibited by the presence of arsenate in the depletion solution. Greatest inhibition however was found not to occur at the level of absorption into the plant root system but rather appeared to be at a site involved in phosphate loading into the xylem. Inhibition at this site was also found to be greatest in low phosphorus status plants. From these results it is suggested that plants of low phosphorus status possess high affinity phosphate xylem loading mechanisms, induced under conditions of phosphorus deficiency, which have a greater susceptibility to arsenate competitive inhibition and toxicity than equivalent xylem loading mechanisms in high phosphorus status plants

The Consumer Revolution: Turning Point in Human History, or Statistical Artifact?

A Farewell to Alms argued based on wages, rents and returns on capital that the English by 1800 were no wealthier than in 1400. An argument against this has been the supposed consumer revolution of 1600-1750. Since ordinary families by 1750 begin routinely consuming former luxury goods, income must have risen much faster than wages through a concomitant industrious revolution. This paper argues that the consumer and industrious revolutions of 1600-1750 are artifacts created by misinterpreting the major source on consumption in these years, probate inventories. Properly interpreted there is no conflict between wages, income and consumption in England 1600-1750.Consumer Revolution Pre-Modern

Intergenerational mobility in England, 1858-2012. Wealth, surnames, and social mobility

This paper uses a panel of 21,618 people with rare surnames whose wealth is observed at death in England and Wales 1858-2012 to measure the intergeneration elasticity of wealth over five generations. We show, using rare surnames to track families, that wealth is much more persistent over generations than standard one generation estimates would suggest. There is still a significant correlation between the wealth of families five generations apart. We show that this finding can be reconciled with standard estimates of wealth mobility by positing an underlying Markov process of wealth inheritance with an intergenerational elasticity of 0.70-0.75 throughout the years 1858-2012. The enormous social and economic changes of this long period had surprisingly little effect on the strength of inheritance of wealth

Technology in the Great Divergence

In this paper, we examine the changes in per-capita income and productivity from 1700 to modern times, and show four things: (1) that incomes per capita diverged more around the world after 1800 than before; (2) that the source of this divergence was increasing differences in the efficiency of economies; (3) that these differences in efficiency were not due to problems of poor countries in getting access to the new technologies of the Industrial Revolution; (4) that the pattern of trade from the late nineteenth century between the poor and the rich economies suggests that the problem of the poor economies was peculiarly a problem of employing labor effectively. This continues to be true today.

Geography is not Destiny. Geography, Institutions and Literacy in England, 1837-1863

Geography made rural society in the south-east of England unequal. Economies of scale in grain growing created a farmer elite and many landless labourers. In the pastoral north-west, in contrast, family farms dominated, with few hired labourers and modest income disparities. Engerman and Sokoloff (2012) argue that such differences in social structure between large plantations in the southern Americas, and family farming in the north, explain the rise of schooling in the north, and its absence in the south. We show, however, that rural literacy across England 1810-45 was not determined by geographically driven inequality. There were substantial differences in literacy by region, but driven by culture not geography. Geography is not destiny.Comparative regional history, European education history, human capital development

Survival of the Richest: The Malthusian Mechanism in Pre-Industrial England

Fundamental to the Malthusian model of pre-industrial society is the assumption that higher income increased reproductive success. Despite the seemingly inescapable logic of this model, the empirical support for this vital assumption in the preindustrial world is weak. Here we examine the relationship between income and net fertility using a large new cross-sectional data set on reproductive success, social status and income for England between 1585 and 1638. We find that for early seventeenth century England, a society seemingly close to a Malthusian equilibrium, wealth at death robustly predicts reproductive success. The richest male testators left behind double the number of children of the poorest. Consequently in the static English economy of this period social mobility was generally downwards. The strong association in England between wealth and reproductive success seems to also extend back to at least 1250.england and economy

Malthus to Modernity: England’s First Fertility Transition, 1760-1800

English fertility history is generally regarded as having been composed of two re-gimes: an era of unregulated marital fertility, from at least 1540 to 1890, then the modern era, with regulated marital fertility, lower for higher social classes. We show there were in fact three fertility regimes in England: a Malthusian regime which lasted from at least 1500 until 1780, where fertility was substantially higher for the rich, an intermediate regime from 1780 to 1890 with fertility undifferentiated by class, and finally the modern regime. Wealthy English men produced substantially fewer children within a generation of the onset of the Industrial Revolution, over 100 years before the classic demographic transition. At the same time the fertility of the poor increased. Determining what triggered this change, however, and why it coincided with the Industrial Revolution, will require further research.Demographic Transition in England

Welfare Reform, 1834

The English Old Poor Law, which before 1834 provided welfare to the elderly, children, the improvident, and the unfortunate, was a bête noire of the new discipline of Political Economy. Smith, Bentham, Malthus and Ricardo all demanded its abolition. The Poor Law Amendment Act of 1834, drafted by Political Economists, cut payments sharply. Because local rules on eligibility and provision varied greatly before the 1834 reform, we can estimate the social cost of the extensive welfare provision of the Old Poor Law. Surprisingly there is no evidence of any of the alleged social costs that prompted the harsh treatment of the poor after 1834. Political economy, it seems, was born in sin.Welfare Reform