Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2001. / Härtill 11 uppsatser.

Thesis (M.S.)--University of Wisconsin--Madison, 1985. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 43-48).

This study aimed to better understand the role of rodents as seed predators and dispersers in the fynbos biome at De Hoop Nature Reserve, South Africa in May and June, 2013. Based on previous studies I hypothesised that the large, nut-like seeds of Ceratocaryum argenteum (Restionaceae) are scatter-hoarded by rodents and that rodent seed choices and seed fates are affected by seed size and hull thickness. Field trials using three seed types showed that smaller seeds with a high reward and low processing cost were consumed significantly(p<0.01) more than large, thick hulled seeds. Application of wire tags to facilitate discovery of relocated seeds had no significant influence on seed choice (p>0.05), but further research should be conducted to determine if spooling of C. argenteum seeds influences rodent seed choice. Smaller seeds with a high-reward and low processing cost showed a significantly greater percentage of usage (p<0.01) where seed stations were encountered and exploited. Rhabdomys pumilio was confirmed as being the most common murid at the study site, however, it seems unlikely that it scatter-hoards C. argenteum seeds, as no consumption or burial of seeds was observed. However, R. pumilio did show an interest in C. argenteum seeds and attempted to consume some seeds or carried seeds over distances not significantly different (p>0.05) from the observed distances between nearest neighbour C.argenteum plants before discarding them on the soil. Additionally, the maximum distance R. pumilio moved C. argenteum seeds was commensurate with the maximum distance between nearest neighbour C. argenteum stands, so the end fate of the seeds remains unknown. Further research should account for seasonal variability in scatter-hoarding behaviour.

No description available.

隨著社會發展, 各種病毒、環境致癌物, 以及不健康食等多種因素導致諸種頑症高發, 並以人類獲得牲免疫缺陷綜合症(艾滋病)和各種腫瘤為代表。從天然產物, 特別是傳統中藥中, 篩選藥用有效成分是治療這類疾病的有效途徑之一。研究發現, 核糖體失活蛋白, 核糖核酸酶, 凝集素, 蛋白酪抑制劑等具有良好的藥用開發前景。本論文著重於從不同植物種于中篩選藥用蛋白, 並對其藥用機制進行研究。 / 是吹研究共純化出六種藥用蛋白。第一, 從苦瓜種子中純化出一種二型核糖體失活蛋白MCL。體外細胞試驗和體內裸鼠試驗顯示MCL 能夠有效抑制鼻咽癌細胞CNE-l 和CNE-2 生長。第二, 苦瓜種于中一個新的核糖核酸酪RNase MC2被分離出來。RNase MC2 通過調控半胱氨酸依賴性細胞死亡蛋白晦(Caspase)信號途徑和絲裂原活化蛋白激酶(MAPKs) 信號途徑誘導乳腺癌MCF-7 細胞凋亡。第三, 從宮粉羊蹄甲種子中提取一種具有抑制腫瘤細胞生長的蛋白酪抑制劑BvvTI 。第四, 從紅花羊蹄甲種子中提取出一與BvvTI 類似的具有抗腫瘤生長的蛋白酶抑制劑BPLTI。 第五，特長秋紫莢豆中存在一個血液凝集素EAPl。EAPL具有制止HIV-l 逆轉錄酶活性, 抗腫瘤, 誘導一氧化氮生成功效。第六, 從另外一種四季豆, 藍虎王, 中提取出一個血液凝集素BTKL。BTKL 通過誘導肝癌HepG2細胞出現DNA 斷裂, 細胞核破壞, 升高線粒體膜通透性, 誘導一氧化氮和細胞因予的表達, 從而導致其凋亡。 / 總之, 上述實驗結果表明, 這六種蛋白具有一定的藥用前景, 可以作為治療艾滋病和不同腫瘤的候造藥物或者候選輔助藥物。進一步體內實驗和臨床實驗評價其療效值得開展。 / Viral pathogens, environmental carcinogens, and unhealthy diets cause severe damage to humans, leading to the acquirement of different stubborn diseases exemplified by AIDS/HIV and neoplasms. Screening of new drugs from natural products, especially from traditional Chinese medicine, provides a promising strategy for these patients. Proteins with potential medicinal applications include ribosome-inactivating proteins (RIPs), ribonucleases, lectins, protease inhibitors and others. The intent of this research proposal is to isolate and characterize proteins with therapeutic potential from plant seeds. / In this project, six medicinal proteins of different origins have been purified by liquid chromatography. One of them is Momordica charantia lectin (MCL), which is a type 11 RIP from the seeds of bitter gourd (M. charantia, BG), with antitumor activity toward human nasopharyngeal carcinoma cells in vitro and in vivo. We have purified a new ribonuclease, named RNase MC2, from BG seeds. It selectively induces apoptosis in breast cancer cells associated with caspase pathways induction and MAPKs activation. Two Kunitz-type trypsin inhibitors, termed BvvTI and BPLTI, have been purified and characterized from the seeds of Bauhinia variegata var. variegata, and B. purpurea L., respectively. EAPL, a lectin with anti-HIV-l reverse transcriptase, antitumor, and nitric oxide (NO) inducing activities was purified from seeds of Phaseolus vulgaris cv. Extralong autumn purple bean. Finally, BTKL is a new P. vulgaris lectin that induced selective toxicity on human liver carcinoma Hep G2 cells. / In conclusion, the above results evince that these proteins are good candidates for the exploration of anti-HIV and/or antitumor drugs or adjuvants. Further research on their efficacies in in vivo as well as clinical trials is warranted. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Fang, Fei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 162-187). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / ABSTRACT --- p.ii / 中文摘要 (CHINESE ABSTRACT) --- p.iii / ACKNOWLEDGEMENTS --- p.iv / PUBLICATIONS --- p.v / LIST OF ABBREViATIONS --- p.ix / LIST OF FIGURES --- p.x / LIST OF TABLES --- p.xii / Chapter CHAPTER1 --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- Prelude --- p.2 / Chapter 1.2 --- Literature review of bitter gourd --- p.4 / Chapter 1.2.1 --- Anti-diabetic property of BG --- p.5 / Chapter 1.2.2 --- Anti-HIV activity of BG --- p.15 / Chapter 1.2.3 --- Antitumor activity of BG --- p.18 / Chapter 1.2.4 --- Looking forward --- p.25 / Chapter 1.2.5 --- Conclusions --- p.29 / Chapter 1.3 --- Research rationale, design, and brief results --- p.35 / Chapter CHAPTER2 --- PURIFICATION AND CHARACTERIZATION OF RIBOSOME INACTIVATING PROTEIN --- p.39 / Chapter 2.1 --- Momordica charantia lectin, a type 11 ribosome inactivating protein, exhibits antitumor activity toward human nasopharyngeal carcinoma cells in vitro and in vivo --- p.40 / Chapter 2.1.1 --- Introduction --- p.40 / Chapter 2.1.2 --- Materials and methods --- p.42 / Chapter 2.1.3 --- Results --- p.46 / Chapter 2.1.4 --- Discussion --- p.59 / Chapter CHAPTER 3 --- PURIFICATION AND CHARACTERIZATION OF RIBONUCLEASE --- p.64 / Chapter 3.1 --- RNase MC2: A new Momordica charantia ribonuclease that selectively induces apoptosis in breast cancer cells associated with MAPKs activation and caspase pathways induction --- p.66 / Chapter 3.1.1 --- Introduction --- p.66 / Chapter 3.1.2 --- Materials and methods --- p.67 / Chapter 3.1.3 --- Results --- p.69 / Chapter 3.1.4 --- Discussion --- p.79 / Chapter CHAPTER 4 --- PURIFICATION AND CHARACTERIZATION OF PROTEASE INHIBITORS --- p.84 / Chapter 4.1 --- Bauhinia variegata var variegata trypsin inhibitor: from isolation to potential medicinal applications --- p.86 / Chapter 4.1.1 --- Introduction --- p.86 / Chapter 4.1.2 --- Materials and methods --- p.86 / Chapter 4.1.3 --- Results --- p.89 / Chapter 4.1.4 --- Discussion --- p.97 / Chapter 4.2 --- A potential human hepatocellular carcinoma inhibitor from Bauhinia purpurea L.seeds: From purification to mechanism exploration --- p.99 / Chapter 4.2.1 --- Introduction --- p.99 / Chapter 4.2.2 --- Materials and methods --- p.100 / Chapter 4.2.3 --- Results --- p.101 / Chapter 4.2.4 --- Discussion --- p.112 / Chapter CHAPTER 5 --- PURIFICATION AND CHARACTERIZATION OF MEDICINAL LECTINS --- p.114 / Chapter 5.1 --- A Lectin with Anti-HIV-l Reverse Transcriptase, Antitumor and Nitric Oxide Inducing Activities from Seeds of Phaseolus vulgaris cv Extra-long Autumn Purple Bean --- p.116 / Chapter 5.1.1 --- Introduction --- p.118 / Chapter 5.1.2 --- Materials and methods --- p.119 / Chapter 5.1.3 --- Results --- p.123 / Chapter 5.1.4 --- Discussion --- p.132 / Chapter 5.2 --- A new Phaseolus vulgaris lectin induces selective toxicity on human liver carcinoma Hep G2 cells --- p.136 / Chapter 5.2.1 --- Introduction --- p.136 / Chapter 5.2.2 --- Materials and methods --- p.137 / Chapter 5.2.3 --- Results --- p.138 / Chapter 5.2.4 --- Discussion --- p.150 / Chapter CHAPTER6 --- CONCLUSION AND FUTURE PERSPECTiVES --- p.154 / Chapter 6.1 --- Conclusions --- p.156 / Chapter 6.2 --- Future perspectives --- p.159 / References --- p.162

Terrestrial mammals affect numerous aspects of plant demography, colonization, and community structure in Neotropical forests. Granivorous mammals destroy seeds via seed predation and seedlings through herbivory, negatively affecting plant fitness. Mammals can also positively affect plants by dispersing or hoarding seeds. Seed fate outcomes are contingent on the interaction between mammal seed handling strategies and the intrinsic anti-predation defenses possessed by seeds. In field experiments at La Selva Biological Station, I investigated how collared peccaries (Pecari tajacu) and Central American agoutis (Dasyprocta punctata) affect five species of large seeds that have various defenses against predation. Overall, peccaries consumed and killed most non-defended and chemically-defended seeds but they could not destroy seeds with physical defenses. Agoutis killed non-defended and physically-defended seeds, but not seeds with chemical defenses. Using seeds of Mucuna holtonii, I investigated how chemical and structural defenses deter mammal and insect seed predation respectively. I also determined how endosperm removal by invertebrates affects seed germination and seedling biomass. Chemical defenses protected seeds from rodents, but not ungulates that digest seeds via pregastric fermentation. Physical defenses protected seeds from invertebrate seed predators, and removal of endosperm negatively affected both seed germination and seedling growth. To determine how scatter-hoarding by agoutis affects seed escape from seed predators, germination, and seedling growth, I created simulated agouti hoards. I also investigated how mammals affect young seedling survival. Hoarding enhanced seed survival, germination, and seedling growth for most species of seeds. Terrestrial mammals killed some seedlings via seed predation rather than by herbivory. Overall, large mammal activity in La Selva negatively affected seed and seedling survival and this likely influences many aspects of forest dynamics.

Soil seed banks are important to the maintenance and restoration of floras. Extant seed banks exhibit unique characteristics with regard to the distribution of seed size and seed density. Seeds were recovered from the Upper Pennsylvanian Wise Formation in southwest Virginia. Structurally preserved seeds were also examined from coal balls of the Pennsylvanian Pottsville and Allegheny Groups, Ohio. The size distribution of the seeds from the Wise Formation is similar to that of structurally preserved seeds of the Upper Pennsylvanian Pottsville and Allegheny Group coal balls. In contrast, the seed size distributions in extant wetland, grassland, woodland and forest habitats are significantly narrower than that of seeds from the Pennsylvanian seed banks. Larger seeds are less dependent on light for germination, and aid in seedling establishment more than smaller seeds, especially in dense stable forests where disturbance events are rare. Large seed size may contribute to increased seed longevity, which reduces the effect of environmental variability on seed germination and development. The significantly larger size of the Palaeozoic seeds may have imparted an advantage for seedling establishment in the dense Palaeozoic forests. The preponderance of large seeds may be a result of the absence of large seed predators (e.g. herbivorous tetrapods), and may have been an evolutionary strategy to minimize damage to the embryo from a predator population dominated by small invertebrates with chewing or sucking mouthparts. The estimated seed density of 192 seeds/m2 in the Palaeozoic seed bank falls within the range of modern seed banks, but at the lower end of modern seed bank densities in a variety of habitats.

Studies of seed dynamics and seedling establishment at the community level in savanna ecosystems are scant, particularly in the tropical savannas of Central Brazil. The Brazilian savannas (cerrado) have the largest diversity of plant species among Neotropical savannas. Cerrado vegetation exhibits consistent changes in tree density and tree size along shallow topographic gradients. Vegetation types differ from closed savannas with high tree density, and a nearly continuous canopy cover in the uppermost portions, to open savannas with scattered short trees in the low portions of the topographic gradients. Whether or not dynamics of seeds and seedlings of woody species are consistent with variations in tree density and tree canopy cover across the cerrado landscape has not been determined, but could potentially influence such spatial patterns of tree density and canopy cover. The main objective of this study was to evaluate seed dynamics (i.e., seed rain, soil seed banks, and seed characteristics) and seedling establishment of woody species in three major cerrado vegetation types (closed, intermediate and open savannas) which differ in tree canopy cover and tree height. These vegetation types are located along topographic gradients of approximately 30 m in elevation and 1000 m in length. I conducted field work from June 2005 to August 2008 at the Instituto Brasileiro de Geografia e Estatística (IBGE) reserve, a field experimental station located 35 Km south of Brasilia, Brazil (15˚ 56' S, 47˚ 63' W, altitude 1100 m). I established permanent plots in each of the three vegetation types to assess seed rain, seed limitation, seed predation, and seed removal. I also quantified density and composition of the soil seed bank in each vegetation type and studied seed characteristics (i.e., kind of dormancy, moisture content, longevity) of 14 common cerrado woody species. In the field, I quantified establishment of woody seedlings in fire-protected savannas as well as in accidentally burned and frequently burned savannas. In the greenhouse I performed experiments to evaluate the effect of litter cover and light level on seedling emergence of 9 common cerrado woody species. Finally, I evaluated the effect of pulses of heat on seed germination of 5 common cerrado woody species under controlled conditions. The overall results of this study show that regardless of tree canopy cover, cerrado vegetation types are limited in seeds and seedlings of woody species, but these limitations are higher in open than in closed savannas. Most woody species do not form persistent soil seed banks along cerrado vegetation types because their seeds are short-lived, predated and quickly removed from the ground. In addition, dispersal season and dormancy appear to control timing of germination at the onset of the rainy season to ensure survival of seedlings in the field. In the absence of fire, establishment of woody seedlings is higher in closed than in open savannas because canopy cover mitigates the stressful environmental conditions of open savannas and thus facilitates establishment of woody seedlings. As a result, closed savannas are likely to maintain higher density of woody elements over time than open savannas. In burned savannas, however, species composition of woody and herbaceous seedlings is significantly affected because establishment of seedlings of woody and herbaceous species decreases but vegetative reproduction increases. This dissertation study indicates that interactions of early life-history stages of woody species with environmental and disturbance factors appear to play a more significant role in maintaining woody cover variations along cerrado topographic gradients than previously recognized.

Free radical and aldehydic breakdown product content were determined, by EPR and UV / visible spectroscopy, primarily in intermediate (desiccation tolerant) seeds of <i>Carica papaya</i> L. (Papaya) and recalcitrant (desiccation intolerant) seeds of <i>Aesculus hippocastanum</i> L. (Horse chestnut), but also in other species covering a range of desiccation tolerances, with a view to determining the role of oxidative stress as a diagnostic marker for desiccation tolerance. Axes of non-senescent highly viable recalcitrant seeds of horse chestnut were metabolically active, contained products of lipid peroxidation, displayed low levels of enzymatic protection against activated oxygen and peroxides, and a two-peak free radical EPR signal. During fully hydrated storage at 16 °C for up to 18 months, seeds exhibited, sequentially, an increase in germination rate, a transient increase in intensities of both the low field and high field EPR peaks, a significant increase in membrane leakage and decrease in seed viability, germination rate, and SOD and peroxidase activities. Drying 'unstored' seeds below and embryonic axis moisture content of 40 to 50 % initiated viability loss. At < 25 % moisture content all axes were inviable and displayed a 2- to 4-fold increase in solute leakage, lipid peroxidation products and the low field EPR signal. Seed desiccation sensitivity increased with hydrated storage. The accumulation of lipid peroxidation products and free radicals on drying generally occurred to a greater extent, or at a higher moisture content, than observed with unstored seeds. The results indicate a mediating role for oxidative stress in recalcitrant seed viability loss which is differentially expressed during hydrated, 'natural' ageing and desiccation. Similar trends were seen in other recalcitrant species with the increase in lipid peroxidation products occurring around the point of viability loss. However the study of a more orthodox species (papaya) revealed no such trends.

Thesis (M.Agric. (Agricultural Economics)) -- University of Limpopo / Maize is the most important cereal crop grown in South Africa. This crop is produced throughout the country under diverse environments. The study only focuses on the technical efficiency because it is an important subject in developing agriculture where resources are limited, but high population growth is very common. Technical efficiency is the ability of a farmer to obtain output from a given set of physical inputs. Farmers have a tendency of under and/or overutilising the factors of production. The main aim of this study was to analyse the technical efficiency of small-scale maize producers in Ga-Mothiba rural community of Limpopo Province. The objective of the study was to determine the level of technical efficiency of smallscale maize producers and to identify the socio-economic characteristics that influence technical efficiency of small-scale maize producers in Ga-Mothiba. Purposive and Snowball sampling techniques were used to collect primary data from 120 small-scale farmers. Cobb-Douglas production function was used to determine the level of technical efficiency and Logistic regression model was used to analyse the variables that have influence the technical efficiency of maize production. Cobb-Douglas results reveal that small-scale farmers in Ga-Mothiba are experiencing technical inefficiency in maize production due to the decreasing return to scale, which means they are over-utilising factors of production. Logistic regression results indicate that out of 13 variables included in the analysis as socio-economic factors, 10 of them (level of education, income of the household on monthly basis, farmer`s farming experience, farm size, cost of tractor hours, fertiliser application, purchased hybrid maize seeds, membership to farmers` organisation, is maize profitable) were found to be significant and 3 (gender, age and hired labour) are non-significant. However, farm size was found to be the most significant variable at 99% level, showing a positive relationship to smallscale maize producer`s technical efficiency. Therefore, it is recommended that government should do the on-farm training since farmers mainly depend on trial and error and farmers` should have access to enough arable land and tractor services. However, farmers need to be trained on matters relating to fertiliser application, on the amount of seeds a farmer should apply per ha, and the importance of using hybrid seed.