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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Biology, 1975. / Bibliography: leaves 42-44. / by Michael Binder. / M.S.

Thesis. 1977. B.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / B.S.

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The ability to withstand environmental temperature variation is essential for plant survival. Formative studies in Arabidopsis have revealed that light signalling pathways has a potentially unique role in shielding plant growth and development from seasonal and daily fluctuations in temperature. In this thesis we further investigate the integration of the light signalling networks and temperature signalling on the molecular level in Arabidopsis. First, we identified the transcript of the bHLH transcription factor LONG HYPOCOTYL IN FAR-RED 1 (HFR1) to be highly dependent on the ambient temperature and under strong control of the red light photoreceptor PHYTOCHROME B (phyB). We found that the long hypocotyl phenotype of the hfr1 mutant was exaggerated in warm conditions, specifically in blue light, downstream of cryptochrome 1. We further show that HFR1 acts in the warm by suppressing the function of PHYTOCHROME INTERACTING FACTOR 4 and 5 (PIF4, PIF5). PIF4 appears to act as a master regulator of several temperature responses and is directly regulated by the phytochromes. Thus, we define a molecular network where red light and blue light signals together with temperature merge on the regulation of PIF4. In the second part of this thesis, we investigate the relationship between temperature and the fluence rate of light on the inhibition of hypocotyl elongation in Arabidopsis. We find that the response to increasing fluence rates of light is highly dependent on the ambient temperature and that PIF4 and PIF5 acting downstream of the major red light photoreceptor, phyB, are essential for this response. In addition, we provide evidence that in cool conditions, PIF activity is under strong suppression by the gibberellin and HY5 pathways specifically at high fluence rates of red light. The collected work of this thesis highlights the importance of the PIF proteins as integrators of temperature and light signals and furthermore, demonstrates that the response to temperature is highly dependent on both the quality and quantity of light.

Light and temperature are two of the most important non-biological signals that plants must be able to sense and respond to. However, it is not just the individual signals, but the interaction between them that is important. In the dark, Arabidopsis has strongly reduced temperature plasticity. The red light photoreceptor phyB and the PIF family of transcription factors have previously been identified as key regulators of this response. Computer modelling was used to study the interaction between the proteins, to explain counter-intuitive behaviour at certain light conditions. A fluence rate dependent response to temperature was uncovered, where high temperature causes a reversal of the normal seedling response to light. In a PIF and phyB dependent manner, increasing light intensity in the warm can lead to an increase in hypocotyl elongation, the opposite of what has been previously published. This was shown to be dependent on an apically derived response to high fluence rates, independent of the Phytochromes. To extend the analysis beyond the seedling stage, the adult phenotypes of light signalling mutants were subsequently characterised at different temperatures. The temperature dependent control of flowering time and leaf growth were both dependent on Phytochrome and the PIFs, but in apparent opposite directions. This demonstrates that the light signalling system in plants is a complex network of signalling factors, affecting each other in a dynamic process to respond to light and temperature.

High-temperature processing of rice needs close attention due to the susceptibility of rice grains to fissures. The present study was carried out to redress the lack of information on the quality of rice dried at high-temperatures using a range of drying air temperatures from 160 - 200??C and grain moisture contents varying from 27 to 33%wb. A laboratory type high temperature dryer-oven was developed and constructed, and the performance was compared with commercial fluidized-bed and spouted-bed dryers. The new column type treatment plant, targeted at small-scale rice farmers was designed to reduce milling breakages was tested for high-temperature treatments. Short term drying (160 ??? 180 seconds) of high moisture rough rice at high-temperatures such as 160 - 200??C increased head rice yield by 5 - 8% in long grain rice and 7 - 11% in medium grain rice. The head rice yield increase achieved was very close to the highest potential head rice recovery possible for a given sample. The head rice yield increase was mainly due to a hardened surface layer of the rice kernel, formed by two effects, a surface fusion and surface gelatinization during high-temperature treatment. This stress protection layer is only effective for a short period (1 - 2 minutes) at high temperatures. Tempering of treated grains, either by storing in gunny bags or rapid cooling, can secure the grains to some extent from grain breakage. The highest head rice yield increase was obtained by ceasing the high-temperature effect at the grain moisture level of 24 - 25%wb. The colour and appearance of high-temperature treated grains were closer to those of untreated grains with the toughness closer to that of parboiled rice. The setback values of high-temperature treated rice measured by RVA, which is a preferred character by consumers, were closer to aged rice. High-temperature treatments did not affect the cooking qualities except a slight increase in water absorption. The alterations in the grain due to high-temperature treatment are limited to only for 8 - 9% of the total volume (mainly outer region) of the rice grain, preserving more than 90% of the grain with raw-rice quality. Structural changes such as complexing of amylose ??? lipid, amylose -protein and denaturation of protein play a dominant role on quality changes than gelatinization. A new method introduced to measure the degree of gelatinization of pre-gelatinized rice, using hot paste viscosity by rapid visco analyser (RVA), was successful. The peak viscosity parameter in the RVA was more suitable for measuring the chemical changes in high-temperature treated rice. Spouted-bed drying technology is not suitable for high-temperature treatment due to the unfavourable conditions for the formation of a hardened layer under intermittent heating and cooling. Fluidized-bed dryers could be used for high-temperature drying, but is not cost effective for the small-scale farmer level. The novel type treatment plant was successful in reducing the amount of broken grains to almost zero, increasing the head rice yield by 50 - 120kg per 1000kg of rough rice. It was also effective as a germination arrester, inhibiting the germination ability within a very short period such as 30 - 60 seconds. This equipment is more effective as a treatment Plant as it reduces moisture by only 1.5 - 2.0% at highest head rice yield recovery. An empirical model was successfully established (R2 = 0.99) for grain moisture content (db) and drying temperature during high-temperature processing. In model validation process, a good agreement was found between predicted and experimental data. The modelling between head rice yield and high-temperature drying was unsuccessful (R2 = 0.89) mainly due the interference from other factors such as initial moisture stress due to re-wetting and uncontrolled post treatment drying environment conditions. The study revealed some breakthrough for the rice industry in addition to its quantitative evaluation of increase in head rice yield. 1. Ability to produce grains with twice the toughness of milled untreated rice, without losing colour and appearance. 2. Fissured grains, previously weakened due to moisture-stress (considered as a loss), can be successfully recovered by treating this high-temperature technique. Currently there is no method available to increase the head rice yield of this type of fissured grains except parboiling, which is not widely accepted among consumers. 3. Drying at 200??C drying temperature completely destroyed the viability of seeds within 40 -60 seconds, hence providing a remedy for germination problems in wet harvests. 4. Since high-temperature drying needs wet rough rice, early harvesting can be done which will reduce shattering losses. This enable the farmers to use the field for an inter-seasonal crop which can utilise higher residual soil moisture in the paddy fields compared to other crops.

A high quality, historical surface air temperature data set is essential for the reliable investigation of climate change and variability. In this study, such a data set has been prepared for Australia by adjusting raw mean annual temperature data for inhomogeneities associated with station relocations, changes in exposure, and other problems. Temperature records from long-term stations were collaborated from the set of all raw data held by the Australian Bureau of Meteorology. These long-term records were extended by combining stations and manually entering previously unused archived temperature measurements. An objective procedure was developed to determine the necessary adjustments, in conjunction with complementary statistical methods and station history documentation. The objective procedure involved creating a reference time series for each long-term station, from the median values at surrounding, well-correlated stations. Time series of annual mean maximum and mean minimum temperatures have been produced for 224 stations, and the adjusted dataset has been made available to the research community. The adjusted data are likely to be more representative of real climatic variations than raw data due to the removal of discontinuities. The adjusted data set has been compared with previously used temperature data sets, and data sets of other parameters. The adjusted data set provides adequate spatial coverage of Australia back to 1910. Additional adjusted data are available prior to this date at many stations. Trends in annual mean maximum, minimum, the mean of the maximum and minimum, and the range between the maximum and minimum, have been calculated at each site. Maximum and minimum temperatures have increased since about 1950, with minimum temperatures increasing faster than maximum temperatures.

The thermoregulatory responses of subjects wearing two different forms of rugby league jersey, one with plastic sponsorship recognition and numbering (trial Gl) and one without (trial G2), and a lightweight alternative (trial G3), were compared with a trial without any form of upper body garment (trial GO). Ten male volunteers, mean age 20.9 (±2.3) years, height 179.8 (±4.7) cm, weight 80.2 (±8.9) kg, and body surface area 1.99 (±0.13) m2, participated in this study. Subjects had a mean maximal oxygen uptake capacity of 56.0 (±6.3) ml.kg.min-1 and a sum of 8 skinfolds of 80.6 (±23.8) mm. Subjects were exercised at approximately 50% of maximal oxygen uptake in a warm humid environment for 50 minutes. Mean ambient temperature was 27.6°C (±0.32) with a relative humidity of 64.7% (±1.44). Measurements of core and skin (7 sites) temperature, heart rate, oxygen uptake, plasma volume, peak lactate concentration, and pre- and post-trial body weight, hematocrit and garment weight were recorded. The statistical results showed that all subjects experienced significant (p ≤.0001) decreases in body weight representing a percentage decrease ranging from 1.2-1.3%. No significant difference was found between trials with respect to body weight change. No significant effect of garment type was found on pre- and post-trial hematocrit, plasma volume changes or peak blood lactic acid concentration. However, mean peak lactate was highest for trial Gl (5.6 mmol.L-1 ±2.2) and lowest for trial G3 (4.6 mmol.L-1 ±1.27). Post-trial core temperature was significantly (p≤ .0001) higher than the resting value; no significant difference was found between trials. The mean absolute increase for all experimental trials was 0.9°C. A significant (p≤.005) difference between mean total (7 sites) skin temperature was found with a post-hoc test revealing that trials Gl and G2 were significantly higher than trial GO; no significant difference was found when comparing trial G3 with trial GO or when comparing the garments between each other. Mean skin temperature under the garment (4 sites) was found to be significantly (p≤.05) higher for all trials involving a garment when compared with mean skin temperature outside (3 sites) the garment; no significant difference was found between trials. Mean oxygen uptake was significantly different between trials (p≤.005), with trial Gl and G3 found to be significantly lower than trial GO; no difference was found when comparing the garments with each other. Post-trial garment weights were significantly (p≤.001) heavier than pre-trial and were significantly (p≤.0001) different when compared with each other. There was no significant effect on heart rate, haematocrit, plasma volume changes, peak blood lactic acid concentration, or core temperature due to garment type. However, differences in skin temperature suggest that the garment used in trial G3 may have a benefit. Further research should consider the impact of increased exercise intensity and/or environmental temperature and humidity on the measured parameters while wearing the garments described in this study.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 42-46). Also available on the World Wide Web.