Th.--Méd.--Paris, 1919-1920. / Paris, 1919-1920, tome 30, n ° 443.

Thesis (M.A.)--Eastern Illinois University, 1994. / Includes bibliographical references (leaves 74-76).

Many species of moths within the family Noctuidae are significant agricultural pests. Specific floral volatiles are attractive to both male and female Noctuidae and may be used to as attractants in crop protection. For the first time the following research compares two types of floral volatile blends - those that mimic natural floral odours and those that are artifical odour blends ('super-blends'). In wind tunnel bioassays and field trials in two diverse geographic locations (Argentina and the United Kingdom) a range of noctuid moth species that are considered crop pests were found to be attracted to both types of the floral odour blends. However, a 'super-blend' containing phenylacetaldehyde, salicylaldehyde, methyl 2-methoxybenzoate, linalool, and limonene (in a 10 : 4 : 2 : 2 : 1 ratio) was found to be the most effective general attractant across the following species: Helicoverpa armigera and gelotopoeon, Heliothis zea, Spodoptera frugiperda, and Autographa gamma suggesting that these compounds are universal cues to this family of moths when searching for flowers. Further behavioural bioassays found that the physiological state of the insect had an important effect on its behavioural response to the floral odour super-blend. Bioassays carried out on H. armigera revealed that gravid insects were significantly less likely compared to virgin insects to make contact with an odour blend baited lure. In addition, insects provided with sucrose solution were significantly less likely to make contact with the odour source compared to starved insects or insects only provided with water. This is the first time this affect has been seen in this species and may have important implications for using these types of floral odours for crop protection. Investigations into the most effective trap for capturing Noctuidae found that a homemade bucket and water trap or funnel and sleeve traps were significantly more effective than UniTraps or sticky traps. During the field trials large numbers of nontarget insects were also captured, including beneficial insects and pest species. By using green coloured traps captures of beneficial hymenoptera (Syrphidae and Apoidea) were significantly reduced. Taken together, the current findings provide insights into how Noctuid moths interact with host odour cues and how they may be used in developing pest management techniques.

Nitric oxide (NO), a diffusible gas molecule, is a major signal molecule in both plants and animals and regulates a plethora of biological processes. S-nitrosylation, a post-translation modification, is conducted by NO, which covalently attaches protein cysteine thiols and forms an S-nitroso thiol. S-nitrosylation plays an important role in plant development and plant immune systems. In Arabidopsis thaliana, S-nitrosoglutathione (GSNO) is the major NO donor for S-nitrosylation, and GSNO reductase (GSNOR) indirectly controls the S-nitrosylation level by turning over the GSNO. An A. thaliana T-DNA insertion mutant gsnor1-3 shows the loss of GSNOR activity and increases the S-nitrosylation level, resulting in loss of apical dominance, reduction of SA accumulation, increased hypersensitive response (HR) cell death and reduced disease resistance against virulence, avirulence and non-host pathogens. Interestingly, loss of GSNOR in Drosophila melanogaster, an animal model system, reduces the resistance against gram-positive and fungal pathogens. Catalase is an antioxidant enzyme and regulates the redox environment through scavenging the hydrogen peroxide (H2O2) to oxygen and water. Previous work in our lab had discovered two gsnor1-3 suppressor mutants, gsnor1-3 spl7 and gsnor1-3 spl8, which restore the loss of apical dominance and partially restore disease resistance. These two suppressor mutants were then identified as the point mutation in CAT3. CAT3, one of the three CAT genes in Arabidopsis, expresses catalase specifically in vascular tissues. To further extend the suppression of cat3 in gsnor1-3, the mutations in CAT3 and its paralogs CAT2 and CAT1, as well as other redox-related genes in gsnor1-3 background, were generated. In the developmental phenotype, only the gsnor1-3 cat3 showed significant changes compared with gsnor1-3. The disease susceptibility and HR cell death in gsnor1-3 cat3 were less than gsnor1- 3 and similar to wild-type. Moreover, the redox-related genes and CAT3 paralog mutations in gsnor1-3 background showed no significant changes in disease resistance against virulence pathogen compared with gsnor1-3 plant. Meanwhile, an SA-dependent (salicylic acid) defence-related gene (PR1, pathogenesis-related gene 1) showed the early expression in gsnor1-3 cat3 plant compared with gsnor1-3 plant. Results of developmental and disease-related phenotypes suggest the suppression effects which turn-over the malfunction in gsnor1- 3 are highly specific to CAT3. The previous report demonstrates that the hydroxyl radical, a reactive oxygen species by-product from H2O2, decomposes GSNO to oxidised glutathione in vitro. The interaction of GSNO and hydroxyl radical may be the possible mechanism of how cat3 suppresses gsnor1- 3. Therefore, we speculated less amount of GSNO in gsnor1-3 cat3 plant than in gsnor1-3 plant and lower level of hydroxyl radicals in gsnor1-3 cat3 plant than in cat3 plant. To evaluate our hypothesis, the content hydroxyl and GSNO were analysed in wild-type, gsnor1-3, cat3 and gsnor1-3 cat3 plants. The total S-nitrosylated protein, which indicates the GSNO content in vivo, was less in gsnor1-3 cat3 than in gsnor1-3. Furthermore, the level of hydroxyl radical in gsnor1-3 cat3 was lower than cat3. Accordingly, the reduction of hydroxyl radical in gsnor1- 3 cat3 may occur due to the reaction with GSNO and vice versa. Similar to what has been found in Arabidopsis, D. melanogaster also reported partial restoration of the immunodeficiency phenotypes of gsnor knock-out flies with an additional mutation in CAT gene. Interestingly, the content of hydroxyl radical in gsnor-/- cat-/- line was less than cat+/-. Collectively, our results suggest an interaction of hydroxyl radical and GSNO may happen both in Arabidopsis and Drosophila. Further research is needed to clarify the interaction between hydroxyl radical and GSNO in Arabidopsis as well as in Drosophila.

The case for improving Phosphorus-Use Efficiency in crops is widely recognised. Although much is known about the underlying molecular and regulatory mechanisms, improvements have been hampered by the extreme complexity of phosphorus (P) dynamics in soil and plants (across all physical scales), including its soil chemistry and uptake, distribution and deficiency responses in plants. The urgency and direction of phosphate research is also being driven by the availability of finite P stocks to farmers and reducing environmental hazards. Thus, systems approaches become essential to identify the most potent (combinations of) target genes for improving phosphate uptake and utilisation in crops. This study has applied these approaches with the aim of increasing understanding of the regulation of phosphate uptake at three separate spatial scales, primarily in rice, but also in Arabidopsis. The first and major part of this study has focused on the cell scale, wherein novel mathematical models for molecular regulation of phosphate acquisition have been developed. Owing to the sparsity of the data, advanced techniques for parameter fitting were employed, which resulted in an original model, which accurately reflected the profiles of all the genes apart from PHO2. It was clear that miR399-mediated degradation was insufficient to explain the apparent early reduction in PHO2 mRNA levels. Five hypotheses were explored mathematically, of which the most plausible is that there is a phosphate-sensitive transcriptional repressor (PsTR) of PHO2 mRNA synthesis. To support this hypothesis, mRNA was extracted from phosphate-starved and untreated roots over a short, 12-hour time course. Quantitative Polymerase Chain Reactions (qPCR) of PHO2 mRNA both confirmed the early decline predicted by the hypothesis and also revealed a temporary restoration of mRNA levels, which points to PHO2 (a type-2 ubiquitin ligase) regulating its own transcript levels. Sensitivity analysis of these models indicates that the utilisation rate of cytosolic phosphate is the biggest influence on this system. Output from simulations with the original and PsTR models qualitatively reproduced the phenotypes of various published phosphate-research papers, with the exception of RNASEQ data in which phosphate-starved rice roots were resupplied with phosphate. In this instance, the observed rapid drop in mRNA levels for PHO2 and IPS1 were incorrectly predicted, pointing to one or more other regulatory mechanisms not represented in these models. The IPS1 gene encodes a long non-coding RNA that has a poly-A tail. Its RNA also binds to miR399 and accumulates to extremely high levels in plant roots during phosphate stress. A sudden loss of IPS1 would release the bound miR399 causing the observed rapid loss of PHO2 mRNA. The observed IPS1 profile can be explained by either the gene having a “super-promotor” that is capable of extremely high RNA synthesis under low phosphate conditions, or the transcript being protected from degradation by phosphate-sensitive RNA-binding proteins. Informatics analyses favour the latter and a revised model incorporating RNA protection was found to have parameters for IPS1 synthesis that are similar to those normally used in modelling gene regulation. The analyses also point to PUMILIO proteins playing this role. The second part of this work has explored the role of tissue geometry in determining root phosphate levels and flux. Multi-cellular vertex-based models of published Arabidopsis and rice root cross-sections were produced using CellSeT, into which equations for phosphate uptake, flux and utilistion were embedded using OpenAlea. Simulations suggest that Arabidopsis trichoblasts have lower cytosolic phosphate levels than neighbouring epidermal cells, because they have a larger area through which phosphate flows into the inner tissues. This implies that trichoblasts are more sensitive to phosphate stress and reduced phosphate levels could therefore be part of the trigger for initiating root-hair growth. Adding root hairs of varying lengths into this geometry shows that a hair does not have to grow much before the phosphate levels in this trichoblast exceeds those in the neighbouring cells and that phosphate flows to them. This potentially suppresses root-hair formation in nearby trichoblasts. The rice simulations show that aerenchyma dramatically reduces cytosolic phosphate in surrounding cells and point to a role for lacunae in rapid uptake of phosphate, without the need for large water fluxes. Alongside aerenchyma, a higher proportion of fluid-filled lacunae could be a desirable trait for improving nutrient-uptake efficiency. At the whole-plant scale for the third part of this work, a time-course dataset has been generated to record the effect of phosphate starvation over 21 days on the uptake dynamics of eleven other macro- and micro-nutrients. This dataset will be of use in future systems studies of nutrient uptake and interactions.

The baobab tree (Adansonia digitata L.), with more than 300 uses and commercial value in EU and US, has been identified as one of the most important edible savannah trees to be conserved, domesticated and valorised in Africa. A decline in baobab populations due to overexploitation and/or changes in climate could have a significant negative effect on African livelihoods. Therefore, it is important to determine potential strategies for conservation and cultivation. The present and potential future distributions of the baobab tree were studied using Maxent niche modelling framework. And, in order to contribute to the selection of superior materials for cultivation, fruit morphology was studied in situ (in Malawi and Mali) while leaf and seedling morphology were studied in situ (in Benin and Malawi) and in a greenhouse experiment. Maxent modelling suggests that predicted changes in climate will have a negative effect on baobab tree distribution in Africa: only a percentage of the present distribution was predicted to be suitable in the future. Some countries were found not to have any suitable habitats for the baobab tree in the future. Several conservation strategies are recommended, such as in situ conservation in Protected Areas; ex situ conservation in Seed Banks and conservation through ‘sustainable utilisation’. Modelling results also showed that the baobab tree could be widely cultivated in most countries in south-eastern Africa and in the Sudano-Sahelian zone of West Africa. India, north-west Australia, Madagascar, north-east Brazil and Mexico could be other suitable places for cultivating the baobab tree outside Africa. Although results from modelling should be validated with in situ seedling experiments, there seems to be potential for the wide cultivation of this species. Significant differences in leaf, fruit and seedling morphology were observed between Benin, Mali and Malawi and also within each country. While some characteristics were correlated with environmental differences between study sites, others might be genetically determined. It seems that genetic and physiological effects play a role in baobab fruit, leaf and seedling morphology. Thus, there is room for selecting high quality baobab planting materials

The aim of the thesis is to contribute to our understanding of how individuals in developing countries cope when faced with environmental risks. These themes are explored while focusing on small-scale farming communities in Wellawaya, south-east Sri Lanka, that are heterogeneously exposed to a particular environmental risk, namely the Human-Elephant Conflict (HEC). First, we examine the strategies which households within farming communities use to cope with exposure to the HEC. We conduct an individual-level household survey of 468 randomly-sampled households across sixteen farming communities which are highly exposed to the HEC. Our unique, cross-sectional data provides a snapshot of the coping strategies which they employ. We find that households which experience greater HEC-related damage are more likely to: rely to a greater extent on non-farm income; cultivate less land in each of the two cropping seasons; and have children who engage in non-farm employment. Next, we investigate the effect of interdependent risk exposure on individuals’ ex-post sharing behaviour. By interdependence, we refer to when an individual’s choice over their own risk exposure directly impacts the risk exposure of another individual. The results from our lab-type risk-and-sharing game suggest that individuals positively reciprocate when another individual’s decision causes them to face lower risk exposure, but do not negatively reciprocate when another individual’s decision causes them to face higher risk exposure. A risk-averse individual who has agency over another’s risk exposure is more likely to share ex-post payoffs, while a relatively risk-tolerant individual does not. Our results suggest that risk attitudes and the balance of power within communities need to be considered by policymakers involved in the design of community-driven development initiatives. Finally, we adopt a mixed methods approach to investigating how heterogeneity in individual returns to a public good and beneficiaries’/contributors’ risk attitudes affect public good contributions. We examine this in the context of Sri Lanka’s HEC and conduct a one-shot, framed, lab-in-the-field, public goods experiment (PGG) which reveals subjects’ contribution preferences when returns from the public good are asymmetric. Subjects also answer a hypothetical contribution question (HCQ) stating their time contributions to the construction of the public good. We find that heterogeneity in individual returns does not have a negative effect on contribution behaviour. Risk-aversion in the PGG, in this context, motivates people to engage in collective risk mitigation. The mixed method approach provides an encouraging and balanced account of communities’ potential engagement in HEC-mitigating public goods provision.

Rhizobia are frequently used in the agriculture sector to enhance legume growth and improve soil fertility. There is growing interest in utilizing biological nitrogen fixation as a means of increasing the potential for sustainable intensification of food production whilst simultaneously reducing environmental damage caused by overuse of chemical fertilisers. Biochar, a recalcitrant carbon-rich product of pyrolysis which may be added to soil as a fertilizer or as a soil improver, alters soil physico-chemical properties usually by acting as a liming agent, by increasing water holding capacity or by modifying cation exchange capacity. The effects of biochar on the soil microbial community are not fully understood. Therefore, the main aim of this investigation was to evaluate the effects of biochar on the Rhizobium-legume relationship and determine whether biochar could increase legume growth. To achieve this aim, a series of growth experiments were carried out under controlled conditions in which broad bean (Vicia faba) was grown with Rhizobium leguminosarum and the symbiosis tested against three concentrations of biochar applied as a soil amendment and with two different char particle sizes. Beans responded well to Rhizobium under char-free conditions but the effects of biochar on the symbiosis were variable and depended on char particle size, concentration and Rhizobium strain (commercial or indigenous). Powdered char inhibited plant growth when in the presence of the commercial rhizobia, but not with indigenous strains. This is an important finding since commercial inocula are commonly used in agronomic situations. Plant available soil nutrients were modified by biochar and surprisingly by an interaction between char concentration and the two rhizobia strains. When beans were co-cropped with wheat, beans performed better when grown with powdered char than without. This is in contrast to the response of bean plants to powdered char in the absence of any competition. Since wheat was generally the superior competitor, powdered char amendment enabled the bean to take advantage of the N-limiting environment that powdered char created and perform better than in the soils that advantaged the wheat. The investigation highlighted the complexity of the system, but identified the importance of char particle size and Rhizobium strain selection.

Orientador: Glaucia Maria Pastore / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-23T08:30:07Z (GMT). No. of bitstreams: 1 Oliveira_JoaquimGilbertode_M.pdf: 47283557 bytes, checksum: 29eaaa38c27e972895c6571b67b3664b (MD5) Previous issue date: 1998 / Resumo: Foram estudados alguns parâmetros de processo para a produção de metilcetonas por uma nova linhagem de Aspergillus sp. pré-selecionada como produtora de lipase extracelular, ainda não relatada na literatura. Através da utilização da técnica de cromatografia gasosa acoplada a detetor seletivo de massas e de cálculo de índice de retenção, foram identificadas as quatro principais metilcetonas produzidas que são: 2-pentanona, 2-heptanona, 2-nonanona e 2-undecanona. As maiores concentrações de metilcetonas (2-pentanona, 2-heptanona, 2-nonanona e 2-undecanona) encontradas quando foi utilizado creme de leite de cabra foram: 0.5, 1.4, 2.4 e 0.4 mg/g de substrato respectivamente e de 0.3, 0.8, 1.04 e 0.22 mg/g de substrato quando se utilizou creme de leite de vaca. Creme de leite de cabra e creme de leite de vaca foram os dois substratos adequados para a produção das metilcetonas, devido a sua composição de ácidos graxos, sendo que, a maior concentração de ácidos graxos de cadeia média esteve presente no creme de leite de cabra e portanto foi obtida uma maior concentração de metilcetonas quando se utilizou este substrato. Foi observado que as melhores condições para produção de metilcetonas foram: período de incubação de 96 horas a 30°C, pH 4,5 e sistema de reação contendo uma mistura de lipase e esporos da linhagem n° 1099. Uma suspensão de lipase isenta de esporos foi incapaz de produzir metilcetonas / Abstract: A newly strain of Aspergillus sp. which produced extracellular lipase was chosen to study some of the process parameters for the production of methyl ketones. Four methyl ketones (2-pentanone, 2-heptanone, 2-nonanone and 2undecanone) were identified from their retention indices and using a gas chromatograph equipped with a mass detector. Of the two substrates used (goat's milk cream and cow's milk cream) the best results were obtained with in the goat's milk cream. The reason for this behavior could be differences in the fatty acid composition of the two substrates. The high concentrations of methyl ketones (2-pentanone, 2-heptanone, 2-nonanone and 2-undecanone) observed were: 0.5, 1.4, 2.4 e 0.4 mg/l respectively, when goat's milk cream was used as substrate. When cow's milk cream was used, the concentrations of methyl ketones were: 0.3, 0.8, 1.04 e 0.22 mg/g respectively. The results suggest good conditions to produce methyl ketones in 96 hours of incubation at 30°C, pH 4,5 and a reaction system with a mixture of lipase and spores of strain n° 1099 / Mestrado / Mestre em Ciências

This study investigated the simulated impact and vibration tests on bruise damage and quality of the British strawberries from winter and summer cultivations. The actual transport of food products was also monitored for the vibration and temperature levels in the city and highways. The winter cultivation produced a superior overall quality of 'Elsanta' and 'Sonata' strawberries compared to the summer cultivation. 'Sonata' fruits were more sensitive to vibration damage in the summer cultivation. The packed strawberry punnet of 250 g was tested in impact and vibration tests. The maximum drop height at 750 mm gave a significantly larger wet bruise level of around 40% than other drop heights (p.0.05). The simulated vibration investigated the three frequencies and three exposure times plus control. The vibrated fruits from the most severe of 5 Hz (1.1 g) for 150 sec had significantly higher wet bruises (50-60%) than for other treatments (p.0.05). The bruise damages increased for both simulated tests after storage at 10°C, 70±5% RH for 3 days. The EC value gave a significantly stronger correlation with wet bruise and severity score as compared to puncture, compression and respiration rate measurements (p.0.01). The EC method is suggested for use as a rapid indicator and a predictor for the bruise assessment of strawberries. The vibration and air temperature levels in the refrigerated truck and semi-trailer were monitored. The overall peak frequency of power density was often found at 10-14 Hz. The vertical vibration was the dominant direction during the road transport. The rear-top position gave a stronger root mean square acceleration value. A gradual increase of vibration level occurred after the first drop in city distribute as well as for a smaller load. The range of temperature during food transport was around 2 to 8oC with a set point at 3°C.