Four endemic medicinal plants from the Yucatan peninsula belonging to genera with little pharmacological and phytochemical reported information and used for medicinal purposes by local communities were selected. The species selected included Jacquinia flammea Millsp. ex Mez, Sideroxylon foetidissimum Jacq. subsp. gaumeri, Serjania yucatanensis Standl., and Serjania adiantoides Radlk. The root, stem/bank and leaves of each plant species were extracted using ethanol and the resulting crude extracts were tested for their cytotoxic effect using the modified MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay followed by a bioassay-guided fractionation of the most active extracts in order to identify the active metabolites. The initial cytotoxic evaluation against HeLa cells at two fixed concentrations (100 and 33.3 µg/mL) identified the root extracts f J. flammea, S. foetidissimum subsp. gaumeri and S. yucatanensis, and the stem/bank extract of S. adiantoides as the most active extracts. The crude extract of roots of J. flammea was subjected to solvent partition using solvents of ascending polarity (pet. ether, CHCI3, EtOAc, BuOH and water). The resulting fractions were tested for their cytotoxic activity. The water fraction of the solvent partition showed the strongest activity against HeLa cells (IC50 = 28.61 ± 2.27 µg/mL). When tested against RAW 264.7 cells, the water fraction also showed significant activity (IC50 = 10.60 ± 1.83 µg/mL). The water fraction was subjected to chromatographic fractionation using open silica gel columns resulting in the isolation of a saponin as the most active metabolite against RAW 264.7 cells (IC50 = 4.76 ± 0.32 µg/mL). The isolated compound was identified using 1D (1H and 13C and DEPT-135) and 2D (COSY, HMBC, HSQC and NOESY and ROESY) NMR and mass spectrometry analysis as sakurasosaponin. The molluscicidal and antifungal activities of sakurasosaponin have been reported but no studies on its cytotoxic activity have been previously reported. The crude extract of roots of S. foetidissimum subsp. gaumeri was subjected to solvent partition using solvents of ascending polarity (pet. ether, CHC13, EtOAc, and BuOH). The resulting fractions were tested for their cytotoxic activity. The BuOH extract of S. foetidissimum subsp. gaumeri showed the strongest activity against RAW 264.7 cells (IC50 = 35.12 ± 4.32 µg/mL) and it was subjected to further chromatographic fractionation using open silica gel columns yielding mixtures of saponin-containing fractions. The crude extract of roots of S. yucatanensis was subjected to solvent partition using solvents of ascending polarity (pet. ether, CHCI3, EtOAc, and BuOH). The resulting fractions were tested for their cytotoxic activity. The crude extract of S. adiantoiodes did not show cytotoxic activity when tested against RAW 264.7 cells.

Within the UK, levels of timber processing are set to increase as the plantation grown forest resource reaches financial maturity. Made up predominately of exotic coniferous species, this resource has been the focus of many recent studies as wood users look to improve their fundamental knowledge of the primary characteristics that will enable them to make more appropriate decisions and capitalise on future opportunities. As a further contribution to this knowledge base, it was the aim of this thesis to determine moisture content variation within Sitka spruce (Picea sitchensis (Bong.) Carr) standing trees and roundwood logs. Within standing trees, moisture content was found to vary significantly in both the longitudinal and radial directions (P<0.001). Longitudinally, the base and top of the trees contained higher quantities of moisture than did the lower and mid sections. Radially, the moisture content at the centre of each disk was very low and this extended outwards before rapidly increasing mid-radius and then reaching a plateau near to the cambium. A sigmoid regression model successfully explained two-thirds of the radial moisture content variation as well as explaining the longitudinal moisture content variation. The radial variation with tree height was described by a shortening of the low moisture content extending outwards from the pith and a softening of the steepness of the increase with the duration extending as tree height increased. Seasonal variation within standing spruce trees was assessed within a plantation forest in northern England. Removing samples from 81 trees throughout a period covering 42 calendar weeks of 2012 revealed no significant effect of season on the moisture content although a link was identified with short-term variation in temperature. However, further analysis on the radial sections confirmed that when the moisture content data were converted to a percentage of total lumen saturation, a significant effect of seasonal variation was observed within the outer sapwood region (P<0.001). Whilst the standing trees as a whole did not demonstrate seasonal variation in moisture content, variation due to seasonal weather did have an effect on the drying of roundwood within the forest. Analysis of c. 25,000 samples, collected over a 6-year period, confirmed that season (dormant or growing) had a significant effect on sample moisture content (P<0.001). Temperature was recorded as having the greatest effect on moisture variation within roundwood whilst the effect of rainfall was not significant, due principally to the unpredictable nature of this variable throughout the year. To identify the radial and longitudinal moisture content change of roundwood during drying, an experiment was carried out to accelerate the drying process on short logs using an industrial oven at a constant temperature (40°C). Total drying time varied between 7 and 28 days prior to post drying analysis of the logs to determine the longitudinal and radial moisture profiles. All logs lost a constant quantity of moisture each day with the logs dried for 28 days losing more than 50% of their starting weight. Longitudinally, moisture was lost from all points along the length of each log with the log ends remaining driest, although these dry areas only accounted for 40% of the total log length. Radially, moisture declined across the log with the greatest amount removed from the outer radius. In order to provide some relevance of the impact moisture content variation has on the forest industry value chain, data collected from a working timber harvesting operation confirmed that variation existed between volume to weight conversions of different products. Within this even-aged Sitka spruce clearfell, volume to weight conversion factors ranged from 1.02 to 1.19. Differences of this magnitude can not only lead to a lack of understanding of between tree variation within a single site, but can also result in an impact on the optimum value recovery expected by each of the parties engaged within the value chain. The results presented within this thesis will help guide timber growers, agents, managers and purchasers in their future decision making when considering the most suitable markets for standing trees or roundwood logs. Improving knowledge of spatial and temporal moisture content variation will potentially result in maximising the forestry value chain and enable the forestry sector in the UK to make more from wood.

This thesis aims to understand the mechanisms involved in pollen transport and deposition in cave environments and the influence of different factors on the composition of the pollen assemblage, with special reference to the problem of the Neanderthal ‘Flower burial’ at Shanidar Cave, Kurdish Iraq. Limited systematic taphonomic work has been done in cave environments, with most of the studies on an ad hoc basis. However, the number of interconnected factors acting on pollen transport, deposition and accumulation in this kind of environments implies that models used for open-air sites are inadequate and demonstrates the need for further taphonomic studies. Surface samples from six caves located in the Zagros Mountains of Kurdish Iraq were collected along front-back transects and outside for comparison in order to evaluate the distribution of anemophilous and entomophilous taxa in relation to the sample location. Additional surface samples were collected from Shanidar Cave along a side to side and perimeter transects to better evaluate the pollen distribution. Water, airfall and animal dung samples were also collected to investigate the influence of those factors in pollen transport. Finally, stratigraphic samples collected during the excavation at the site were analysed for pollen and for particle size distribution. Results show that simple sac-like caves with little or no influence of factors such as water, humans and animals are characterised by broadly predictable patterns of pollen distribution with a positive correlation between anemophilous pollen and vicinity to the cave entrance and entomophilous pollen and distance from the cave entrance. Caves with active biotic vectors and/or more complex geomorphology show instead more irregular patterns. Cave SLS203 presents an inverse anemophilous/entomophilous distribution that is likely to be related to its geomorphological complexity (a second entrance at the back of the cave influencing the air circulation) and to the presence of animals. Shanidar Cave presents a very irregular distribution which is likely to reflect a combination of factors such as the mixing of surface sediments caused by the tourists visiting the site, the pollen transported by animals and that moved by the wind. Other factors, such as water input and cave entrance flora, seem not to play an important role in ii Kurdish Iraq, while they appear to strongly influence pollen distribution in caves elsewhere (e.g. Coles, 1988; Simpson, 2006). The stratigraphic samples were sterile or contained few pollen grains, probably because the aeolian nature of the sediments, deposited during stadials, with low pollen deposition and high sediment influx. Finally, clumps of pollen of both anemophilous and entomophilous taxa have been found for different taxa in all the caves. Leroi-Gourhan (1975) had suggested that similar clumps found in the vicinity of Shanidar IV remains were evidence for burial with flowers but their presence on the surface demonstrates that they can occur naturally and that other explanations should be considered. Moreover, the high amount of Lactuceae and the presence of older pollen grains in her samples suggest a strong taphonomic imprint not necessarily resulting from anthropogenic activity.

Previous studies have shown that mitochondrial petites of the yeast Saccharomyces cerevisiae appear to have some advantage over their wild type counterparts in terms of fermentative performance. In this thesis evidence is presented that inhibition of the respiratory chain by chemical or genetic means leads to an increase in ethanol formed per unit sugar and a decrease in biomass per unit sugar. The genetic studies involve a mutation in formation of subunit III of the cytochrome £ oxidase complex (pet!22) and a mutation in putative mitochondrial pyruvate transport (tpyl). The chemical study involves inhibition of mitochondrial pyruvate transport by a specific inhibitor alpha-cyano-4-hydroxycinnamic acid. To try and discover more of the nature of the tpyl mutation a gene was cloned from a yeast centromeric genomic library which complemented the mutation. The insert containing the complementing gene was reduced in size and sequenced. An open reading frame containing 1698 nucleotides coding for 566 amino acids was discovered. After comparison to databases the gene appeared to be undiscovered to date. No similarity was found between the translated protein and others on databases with the exception of the FAS2 gene of Penicillium patulum. Studies of isolated mitochondria and cell growth pattern, of the tpyl mutant, revealed data typical of a classical petite mutation rather than a mutation in a regulatory gene as described by the original paper describing the mutant.

Myxococcus xanthus Is a Gram negative, heterotrophic, soil dwelling, bacterium. It exhibits a number of interesting characteristics. Including the synthesis of carotenoids. Carotenoids protect the cells from lethal photolysis by protoporphyrin IX In the presence of light (Burchard and Dworking, 1966, J.Bac., 97, 1165-1168). The region of DNA which encodes the proteins responsible for the control of carotenogeneals by light has been identified (Martinez-Laborda and Murillo, 1989, Genetics, 122, 481-490, Hodgson, manuscript in preparation). This region, termed oafQRS, is under the control of a light inducible promoter, termed pQRS. The alma of study were to determine the mechanism by which light regulates pQRS, and to establish its possible application to biotechnology by reconstituting the light inducible mechanism in a heterologous host, Escherichia coll. To facilitate these studies the pQRS promoter was linked to a promoter-less lacZ gene, allowing a simple assay for promoter activity. The pQRS region exhibits two expression patterns In E. coll, which depend on the size of the pQRS region studied. Only one of these is believed to be the expression of pQRS, showing a low level of expression which may be increased in the presence of the carQRS region. The second expression pattern is believed due to a promoter-like region upstream of pQRS, term pX. A E. coli strain permeable to protoporphyrin IX has been isolated. This strain exhibits photolysis, in the presence of protoporphyrin IX, which may be quenched by carotenoids, and thus is an ideal system for further studies of the Induction of pQRS in E. coll. The pQRs promoter has been extensively studied in its native host. Genetic studies in which a mutant of M. xanthus deleted for carQRS was reconstituted with fragments of the region showed an open reading frame previously without function was required for full expression from pQRS . Light Induction of batch cultures of M. xanthus was used to study in part the physiology of the inductive process. The level to which pQRS activity is induced by light decreases throughout the growth cycle, and is subject to feedback control by endogenous carotenoids. The pQRS promoter may be induced by defined laser light of wavelength 410nm, the maxima of absorption by protoporphyrin IX. Extensive continuous culture experiments showed that the pQRS promoter may be induced in the dark by increasing the oxygenation of the culture. Typically two-fold induction was seen. In addition it was shown that the level of oxygenation determined the extent to which light stimulates expression from pQRS. The reactive species involved in the stimulation of pQRS activity by light and oxygen was investigated. The promoter could not be induced by exogenous hydrogen peroxide, or by the presence of methyl viologen, a superoxide radical generator. However, it was shown that the photoactive dye, Toluldlne Blue O, could induce expression from pQRS under red light stimulation which does not stimulate the native photoreceptor. This Induction was shown to be due to singlet oxygen by a singlet oxygen quencher. Additionally it was shown that Induction of pQRS by the native photoreceptor could be quenched in the same way. Thus It has been shown that light Induces carotenogenesis in M. xanthus through singlet oxygen.

Field work with natural phytoplankton assemblages using conventional oceanographic techniques, has established the limited ability of such methods to be able to identify the existence of iron-deplete conditions in the North Atlantic Ocean. Such results confirmed the requirement of "novel" detection methods to determine whether phytoplankton are iron limited in non-productive waters. Carotenoid-containing cell walls from the marine cyanobacterium Synechococcus WH 7803 contained two major polypeptides of Mr - 94,000 and 67,000. The larger of the two appeared to be heat modifiable, a characteristic of porins. Western blot analysis showed that the cell walls from different species of cyanobacteria and one prochlorophyte exhibited a high degree of antigenic relatedness. The effects of iron-deplete conditions upon the outer membrane protein (OMP) profile of Synechococcus WH 7803 was simulated by the addition of 15 nq ml-1 EDDA to normal growth medium. Initial SDS-PAGE analysis revealed the presence of specific iron-regulated outer-membrane proteins. The size of the polypeptides present depended upon the type of iron limitation imposed. Light-stimulated 35S-methionine uptake and incorporation into protein was observed with Synechococcus WH 7803. The reproducibility and sensitivity of this technique resulted in its use as a detection system for the synthesis of iron- regulated membrane proteins. After 21-48 hr growth of Synechococcus WH 7803 cells in iron-deplete medium a protein of Mj. 36,000 was synthesized. Repression of the protein's synthesis occurred after 24 hr growth in iron-replete medium. This protein was localized to both the internal membrane and the cell wall. By contrast, antibodies raised against the 36,000 Da polypeptide were able to detect the protein in internal membrane, cell wall and whole cell fractions of Synechococcus WH 7803 cells grown in both iron-replete and deplete medium. This suggests that the protein is expressed constitutively. Although partial characterization of the 36,000 Da polypeptide has, as yet, been unsuccessful, certain characteristics of the protein were reminiscent of those of TonB. Antibodies raised against a synthetic peptide containing the x-proline dipeptide repeat of TonB were unable to detect a similar protein in Synechococcus WH 7803. However, Southern hybridization analysis using both the S. typhimurium tonb gene and an oligonucleotide probe constructed against the TonB Lys-Pro dipeptide repeat, suggest the presence of a TonB homologue. Once the blockage has been removed from the N-terminus of the 36 kDa protein the sequence should hopefully yield conclusive evidence as to the protein's function. Sequestration of iron by Synechococcus WH 7803 cells was observed using flame atomic absorption spectroscopy on whole cell samples. Such sequestration suggests the presence of iron storage proteins. Western blot analysis and Mossbauer spectroscopy confirmed the presence of an iron storage protein namely bacterioferritin. The 57Fe associated with the storage protein was in the same form as that found in the bacterioferritins of B.coli and P.aeruginosa, as determined by Mossbauer spectroscopy. In addition, siderophore production has not been found in this cyanobacterium.

The enzyme L-asparaginase (L-asparagine amidohydrolase EC 3.5.1.1) has been shown to possess antitumour activity and has been extensively used over many years for the treatment of childhood acute lymphoblastic leukaemia. Today, this enzyme is produced commercially from either the enteric bacterium Escherichia coll or the plant pathogen Erwinla chrysanthemi NCPPB 1066. The following sections of this chapter have been written in the form of a review which summarises the available literature concerning L- asparaginase. The clinical, physical, biochemical, commercial and regulatory aspects of this enzyme are discussed, with particular emphasis on the chemotherapeutic L-asparaginase from Er. chrysanthemi NCPPB 1066, since this is the subject of the present study, in addition, the reader is introduced to the genus Erwinla and to the variety of tools that have been developed for the genetic analysis of a number of Erwinia species.

The uptake and transport of vanadium in several higher plant species has been examined. Studies utilizing excised Hordeum roots have revealed the uptake patterns of two different ionic species of vanadium (V02+ and V03) to be similar. Both ionic forms exhibited a large extracellular component in their uptake. This extracellular component was shown to be exchangeable with a number of agents but was most effectively removed by a post uptake treatment in a solution of chromium(VI). This removal of extracellular vanadium by chromium was considered to be a genuine exchange process although the mechanism involved is unclear. The effect of temperature, pH, metabolic inhibitors and complexing agents were also examined and found to be similar for the two ionic forms considered. Concentration dependent uptake of the two ionic forms was also examined. Saturation kinetics were observed when a wide concentration range of vanadium (0.1-5.0 MM) was employed. These results were considered suggestive of conversion of vanadium to a common form within root tissues. Whole plant studies utilizing Zea and Vicia also revealed highly similar uptake patterns for the two different ionic species of vanadium. Irrespective of the ionic form of vanadium supplied to the plant marked retention of vanadium within the root tissues was observed. Analysis of vanadium root-shoot transport patterns in plants supplied with different ionic species of vanadium suggested that a common form of vanadium was being transported in both cases. Possible interactions between vanadium and other ions within the plant are briefly considered. ESR studies utilizing Hordeum clearly illustrated the ability of plant roots to reduce pentavalent vanadium to the tetravalent form. Evidence from all three lines of study is discussed and considered to support the suggestion that vanadium within plant roots exists in the reduced tetravalent form. This is thought to be of prime importance in determining the mobility of vanadium within plant tissues.

No description available.

Disused railway lines make excellent vehicles to study ecological processes being linear, of fixed width, constructed in the same way, with potential vegetation influences such as time since abandonment and climate being easy to discover. Moreover they are rarely studied. Thus the current study fills a gap in the literature. Samples were taken from a total of 176 releves across 35 sites on 22 different railway lines within England and Wales. The communities were analysed using the standard UK phytosociological method, the National Vegetation Classification (NVC). Few similarities were found with published NVC communities. A large number of communities had affinities with MG1 Arrhenatherum elatius grassland but with un-described sub-communities, with ruderal species or wood and scrub species as major components. Similarly, a number of communities had affinities to OV communities but with different constant species. Hence it is difficult to apply the NVC to synanthropic habitats and that there are ruderal communities in existence that are not described in the NVC. A modified Braun-Blanquet approach to analysing the vegetation data was also undertaken. Hierarchical analysis identified seven clusters equating to communities. Species characteristic of each community were identified using Indicator Values, although these species rarely had both high fidelity and exclusivity. The potential contribution of environmental, temporal and edaphic variables to the development of these communities was assessed. This was underpinned by the theoretical question of succession. Is it an ordered progression through to a climax community or is the process much more stochastic ? There is no simple relationship between time since abandonment and any measure of successional progress. However CCA analysis showed that some factors, primarily abiotic, were significantly associated with community composition. Time since abandonment only becomes significant when it is combined with soil factors. This suggests that vegetation composition is not entirely random in these communities.