This thesis describes a series of experiments, firstly into mammalian arsenic urinary metabolites and secondly into the use of phospholipase enzymes as a tool to assist in the characterisation of lipids extracted from the seaweed, <i>Laminaria digitata</i>. HPLC-ICP-MS has been used as the principal analytical instrument, often coupled with ES-MS. The ICP-MS. Provides a ‘hard’ ionisation process and yields data specific to arsenic. ES-MS (electrospray mass spectrometry) is a ‘soft’ ionisation technique that allows analysis of the intact molecules. Analysis of the urine from Scottish Blackface sheep that had been the subjects of a feeding trial in which the sheep routinely ate <i>Laminaria</i> <i>digitata</i> as part of their normal diet revealed the presence of the short chain fatty acids, dimethylarsenopropionic acid and dimethylarsenobutanoic acid. These had previously only been seen in the urine of human volunteers following ingestion of cod liver oil. Further controlled feeding trial experiments were performed in which cod liver oil, <i>Laminaria digitata</i> and aqueous extract of <i>Laminaria digitata</i> was ingested by human volunteers. Similarities and differences in the arsenic urinary metabolites resulting from the different feeding trial regimes were investigated. The continual presence of arsenobetaine in the urine produced by the volunteers, including the control samples, raised questions concerning the accepted retention time of arsenobetaine in the body that were answered by performing another feeding trial, the results of which have been published. Phospholipase D, C, and A2 were used to cleave arsenic containing phospholipids extracted from freeze dried <i>Laminaria digitata</i>. Some valuable information was gained and the technique shows great promise for future study.

Abstract Recently there has been a renewed impetus in the search for novel ingredients to be used in the cosmeticindustry and Baobab (Adansonia digitata L., Malvaceae) seed oil has received high interest. In this study,a commercial Baobab seed oil sample was characterised (fatty acid content) using GCxGC-ToF-MS and apilot study on the safety and efficacy of the seed oil was performed. The safety and efficacy of Baobab seedoil after topical application was determined using healthy adult female caucasian participants (n = 20).A 2× magnifying lamp was used for visual analysis, while for monitoring and evaluation of the irritancylevel, transepidermal water loss (TEWL) and hydration level of the skin, Chromameter®, Aquaflux®andCorneometer®instruments, respectively, were used. In addition, Aquaflux®and Corneometer®instru-ments were used to assess occlusive effects. Thirteen methyl esters were identified using GCxGC-ToF-MS.The major fatty acids included 36.0% linoleic acid, 25.1% oleic acid and 28.8% palmitic acid with 10.1%constituting trace fatty acids. The irritancy of sodium lauryl sulphate (SLS) in the patch test differedsignificantly compared to both de-ionised water (p < 0.001) and Baobab seed oil (p < 0.001) but the dif-ference between the irritancy of Baobab seed oil and de-ionised water was not significant (p = 0.850).The moisture efficacy test indicated a reduced TEWL (p = 0.048) and an improved capacitance moistureretention (p < 0.001) for all the test products (Baobab oil, liquid paraffin, Vaseline®intensive care lotionand Vaseline®). The occlusivity wipe-off test indicated an increased moisture hydration (p < 0.001) anddecreased TEWL particularly when Baobab oil was applied. Baobab possesses hydrating, moisturising andocclusive properties when topically applied to the skin. Baobab seed oil could be a valuable functionalingredient for cosmeceutical applications.

The machair of the Outer Hebrides, Scotland, is a cultural landscape, designated as a Site of Special Scientific Interest. Crofting on the machair is a sustainable low-input, low-output system, producing crops for livestock fodder, which has been practiced for hundreds of years. Recent demographic changes have affected the agricultural practices, with unknown, but potentially negative effects on these marginal soils. The present work investigated the effects of some of these changes in agricultural practices, in particular the effect of amendment with kelp (Laminaria digitata), a brown seaweed, ploughing and land use on soil stability, water repellency and soil microbiology. Furthermore, the effect of kelp on plant seed germination and root development was assessed. The results showed that machair soil is resilient towards amendment with kelp and synthetic NPK fertilizer in a single growing season, and that this resilience was not caused by rapid degradation of kelp. There was evidence that kelp inhibits soil fungi, but increases total microbial biomass and activity. The soil was slightly to severely water repellent. The causes of this repellency could be attributed to a number of factors including plant organic matter, manure, land use and organic matter within aggregates. Kelp increased seed germination in a number of key native machair plants and crops, suggesting that kelp may affect native plant community composition and crop yield. Also, a promoting effect on root development of kelp was seen in some plant species, with a threshold concentration above which it became inhibiting. Furthermore, these results confirmed the presence of plant growth regulators in kelp. The above findings are relevant not only to the machair, but also to other marginal sandy soils, and to the use of seaweed species as organic alternatives to conventional synthetic fertilizers.

No description available.

Caption: “Water-home sewerage in a Baobab Tree at Mutino-Mulilo (?Katima), Eastern Caprivi. Headquarters of Major Trollip, Native Commissioner. Ca. 1940’s”

@Adansonia digitata@L. (Malvaceae) is a huge multipurpose tree of the savannahs of sub-Saharan Africa with high economic potential for local communities. The edible fruits and leaves are known for their high nutritional values and can be used fresh or processed. However, a high intra-specific variability regarding morphology, genetics and nutritional content of baobab and its products is documented for several African regions, while data for Kenya is largely lacking. This study aimed at documenting the genetic and morphological variability of baobab accessions in Kenya and at checking the presence of the newly described diploid baobab species @Adansonia kilima@. Samples were collected from 204 baobab trees from seven populations defined by geographical distance in South-eastern and Coastal Kenya at altitudes of 6-1,058 m asl. Leaf or bark samples for genetic diversity assessment were collected from all 204 trees, while leaves only from 65 and fruits from 76 trees (all in inland locations) for morphological analyses based on the publication Descriptors for Baobab. Nine microsatellite loci were used to assess genetic variation and results analysed with specific software because of the tetraploid nature of baobab. Overall genetic diversity was high and all loci were polymorphic. The mean gene diversity was 0.803 and observed heterozygosity was 0.907. Analysis of molecular variance (AMOVA) revealed low variation among populations (12.4%) and high variation within populations (87.6%). Bayesian clustering and Principal Coordinate Analysis divided the accessions into two clusters, one with only inland and one with coastal accessions. Although the presence of @Adansonia kilima@ was previously postulated for Kenya, flow cytometry did not detect any among the analysed samples as only tetraploids were observed. Regarding morphological characteristics, no differences among the fruit accession from inland populations were found (no fruits were collected in coastal areas). Leaf morphological data showed significant differences between inland and coastal populations with longest leaflets and leaf petioles in accession from the Coast, thus confirming the results obtained for genetic analysis. This study contributes to the overall knowledge of the genetic diversity of baobab in Kenya and can contribute to the development of germplasm conservation strategies and domestication programs for baobab.

Thesis (M. A. (Anthropology)) --University of Limpopo, 2016. / The baobab tree (Adansonia digitata), with more than 300 cultural and ethnobotanical uses in Africa has been identified as one of the most important savanna trees to be conserved, domesticated and valorised on the continent. A decline in baobab populations due to overexploitation could have a significant negative effect on African livelihoods. Therefore, it is important to determine potential strategies for the conservation of this tree species. The study aimed to explore the cultural significance and ethnobotanical use, as well as conservation of baobab trees by the Sagole community in the Vhembe District of the Limpopo Province, South Africa. Furthermore, the conservation efforts of this community and the provincial government were also elucidated. In the Sagole community 40 local community members, aged 20 years and older, were selected via convenience sampling. A semi-structured questionnaire was employed to collect information on the cultural significance of baobab trees to members of this community. Research questions focussed specifically on identifying folk taxonomy, the transfer of species-specific information to younger generations, and cultural taboos pertaining to the baobab. It has been discovered that young people of Sagole are not well versed in the cultural value pertaining to baobabs. Furthermore, members of the community and the village head (chief) have limited knowledge related to taboos associated with this species. Thus, when individuals transgressed a taboo related to this tree species there is no formal punishment. Sagole community members use baobab trees for various purposes such as food and medicine. The species is used medically to cure various ailments. Most inhabitants in the community harvest this tree. The most common plant parts harvested for cultural use are the fruits, bark, roots and leaves. However, community members have limited knowledge about the taboos related to harvesting of this majestic tree.

Alors que la base des interactions hôte-pathogène chez les plantes terrestres sont désormais très bien décrites, que ce soit au niveau physiologique, métabolique ou moléculaire, chez les macroalgues marines les investigations n'en sont qu'à leur début. Chez l'algue brune L. digitata, les études sur les réponses de défense suite à l'élicitation par les oligoguluronates, ont permis d'appréhender la transduction du signal conduisant à la production d'un burst oxydant, ainsi que la mise en place tardive de la résistance. Le métabolisme halogéné est particulièrement actif chez cette algue. Il semble être impliqué dans les réponses de défense comme en témoigne l'émission d'iode moléculaire et de composés organiques halogénés volatils, suite à l'élicitation par les oligoguluronates. Dans ce contexte, j'ai étudié la régulation du transcriptome de L. digitata en réponse à l'élicitation par les oligoguluronates, par hybridation soustractive suppressive, macroarray et PCR Quantitative. J'ai ainsi identifié dix gènes codant notamment des haloperoxydases, des thiorédoxines et des enzymes de la voie des pentoses phosphates. L'induction de ces gènes suite à l'élicitation suggère une gestion originale du stress oxydant chez L. digitata. L'implication du métabolisme halogéné dans les réponses de défense a été mise en avant par l'expression différentielle de certains gènes codant des haloperoxydases. La régulation spécifique de certains de ces gènes apporte la première preuve expérimentale que les différents membres d'haloperoxydases ont évolué vers des fonctions biologiques spécifiques. L'identification de ces gènes comme marqueurs moléculaires des réponses de défense a permis d'établir la première modélisation de la signalisation intracellulaire conduisant à l'activation de gènes de défense de L. digitata et de souligner le rôle du peroxyde d'hydrogène dans plusieurs voies distinctes. Les outils développés et les marqueurs moléculaires identifiés permettront d'approfondir la compréhension des réponses de défense des macroalgues dans le contexte des interactions biotiques et de la signalisation à distance.

Tree species belonging to the genus Acacia have a significant impact ecologically and economically in southern Africa. Together with the African baobab, these trees are recognized as icons of the African landscape. They are widely distributed in this area and extensively used by local communities as sources of energy, stock feed, medical remedies and building material. There is still a substantial lack of knowledge regarding the ecological association between these plants and other living organisms such as fungi. This is, however, not new to the African continent where fungi are generally poorly studied and collected, and it is envisaged that many new fungal species will be discovered as scientists focus their efforts more on this geographical niche. An example of the lack of knowledge on the fungal biodiversity in Africa is reflected in the limited reports of members of the Botryosphaeriaceae, described to date from Acacia spp.. A review on phytopathogens in South Africa by Crous et al. (2000) indicated no records of the Botryosphaeriaceae associated with native Acacia spp. Despite the importance of many species within the Botryosphaeriaceae as pathogens, knowledge about the true diversity and taxonomy of species in this family is limited, especially where native plant communities are concerned. This dissertation attempts to contribute to knowledge on the associations between members of the Botryosphaeriaceae and indigenous Acacia trees in southern Africa, and the possible role they may play in diseases of these trees. Chapter 1 represents a literature review that focuses on fungi previously associated with Acacia spp. on the African continent. Information provided in this chapter refers to available reports on pathogens and saprophytes occurring on Acacia spp. that are both native and nonnative to Africa. Special reference is made to those occurring in southern Africa. Due to the concern of the introduction of new pathogens in areas where native and non-native plants are co-existing, emphises is also placed on the possibility of pathogen-host jumps between native and non-native Acacia spp. The potential threat they might pose to the future biosecurity of these important trees is discussed. Acacia mellifera, also known as the blackthorn, is one of the native African Acacia spp. that has been extensively studied. This tree is threatened by a serious die-back disease with symptoms similar to the die-back typically caused by members of the Botryosphaeriaceae. In an effort to understand the association of the Botryosphaeriaceae with native Acacia spp. in southern Africa, a study was undertaken to search for the presence of these fungi on especially A. mellifera in Namibia and the Pretoria area in South Africa. Other Acacia spp. were also sampled in cases where they were present in the same areas as A. mellifera. These results are presented in chapter 2. In a previous study, the fungal diversity of native trees and plant species in the Northern Cape Province of South Africa was studied. This resulted in the isolation of a number of fungi that resembled the morphological characteristics of the Botryosphaeriaceae. In chapter 3, these fungi were further identified to species level based on morphological and phylogenetic characteristics. In chapter 4 an attempt was made to compare the Botryosphaeriaceae that are associated with important native trees with those occurring on non-native trees. To accomplish this, a pilot study was done to investigate the presence of the Botryosphaeriaceae on A. mearnsii in the Gauteng Province of South Africa. Results from chapters 2 and 3 on native Acacia spp. from Namibia and South Africa served as the bases of comparison for this chapter. Results of previous studies that investigated diseases of plantation grown A. mearnsii were also included for comparison. Lastly, a summary is included to review the results of this study and also the significance and impact these results made, not only on the taxonomy of the Botryosphaeriaceae, but also understanding the fungal biodiversity of indigenous tree species in southern Africa. To date, this is the most extensive study of the Botryosphaeriaceae associated with native African Acacia spp. and it is also the first study that resulted in the describtion of so many new species in this group of fungi from a single host. Results from this study indicated that there is a significantly greater diversity in the Botryosphaeriaceae associated with native Acacia spp. in southern Africa than was previously thought. This dissertation attempts to form the basis for future studies to finally understand the interactions between the Botryosphaeriaceae and their native hosts as well as their role and threat as pathogens to indigenous and economically important plants. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Microbiology and Plant Pathology / unrestricted

Tests carried out to determine the enzymatic activity of the fungus Xylaria Digitata showed the presence of Diastase, Invertase, Cytase, Maltase, Emulsin and Erepsin. Oxidase, protease and Amidase were not found to be present. / Master of Science