This study is designed to (a) demonstrate the highly productive nature of the littoral area as compared to the pelagic region, (b) the possible importance of phyco-periphyton in the diets of fish, (c) the effects of meteorological conditions on distribution of phytoplankton, and (d) a demonstration of the invalidity of using artificial substrates as a universal means of measuring productivity.

The purpose of this investigation was to determine the site of the carotenoid pigments in C. spp. strain 7E1C as a step towards resolving the role of the pigment in the cell.

Eukaryotic organisms are divided into about 30 groups today, yet there still reamain many groups whose classification in the eukaryotic tree we are not sure about. This study focused on jacobids, a evolutionary important protist group from the Excavata taxa. Together with Heterolobosea, Euglenozoa and Tsukubamonadida, jacobids constitue a Discoba subgroup of Excavata taxa. Jacobids are significant mainly for their mitochondrial genome, which structurally resembles the original α-proteobacterial genome of the free-living ancestor of mitochondria. Some jacobids have their mitochondrial genome simplified, making them potential candidates for a model group used to study the mitochondrial evolution. However, too few members of jacobid group have been identified so far and the exact phylogeny of the group must be thoroughly understood for the detailed study of mitochondria evolution. This study focuses on broadening the taxonomic coverage of the jacobid excavate protists Andalucia. Twenty new strains of Andalucia have been established into stable culture, their morphology was assessed and SSU rDNA sequenced. Based on the phylogenetic analysis, Andalucia incarcarata species divides into three morphologically almost indistinguishable lines representing three species. Further, this study characterized a...

Cassava ranks seventh in terms of worldwide crop production, providing a staple for over half a billion people. The production of cassava is limited by several factors, with post-harvest physiological deterioration (PPD) of storage roots a major constraint. PPD is a process initiated on harvesting and mediated by reactive oxygen species (ROS) that ultimately renders storage roots unpalatable and unmarketable. It is similar to a conventional plant wound response, but crucially lacks efficient wound repair and down-regulation of stress signalling. Therefore, the strategy utilised here to modulate PPD focussed on increasing the ROS scavenging ability of storage root tissue through a biotechnological approach. Three expression plasmids were produced, harbouring cassava genes encoding the antioxidant enzymes APX, CAT and SOD under the control of the storage rootspecific StPAT promoter. In addition, a reporter expression plasmid was created, with StPAT driving the expression of GusP. Transgenic Arabidopsis plants containing the StPAT::GusP cassette demonstrated root-specific GusP staining. Non-root tissue also showed wound-inducible GusP activity conferred by the StPAT promoter. This novel activity was detected almost immediately after wounding and occurred independently of ethylene, MeJa and ROS. The 3’ 261 bp of the StPAT promoter was sufficient to confer wound-inducible expression and contained putative wound responsive cis regulatory motifs. Analysis of PATATIN function indicated a role during early responses to wounding in the liberation of free fatty acids from cell membranes. Over-expression of the target genes in the model plant Arabidopsis increased the antioxidant enzyme activity in the roots of selected lines. Transgenic plants generally exhibited similar levels of oxidative stress resistance to wild-type plants, a result due in part to the efficient nature of the oxidative stress response of Arabidopsis – the APX activity of wild-type plants increased to transgenic levels under H2O2 stress. However, PPD in cassava is at least partially the result of a poor antioxidant response to harvesting, and so transformation of cassava with the expression plasmids remained a viable strategy. Transgenic cassava plants harbouring the expression cassettes are being generated and will soon be assessed for PPD resistance.

This thesis investigates the impact of two invasive ecosystem engineers on the river banks. Invasive species generate significant global environmental and economic costs and represent a particularly potent threat to freshwater ecosystems. Ecosystem engineers are organisms that modify their physical habitat. Therefore this thesis will explore the interaction of these two types of species and their impacts on the example of the impact of signal crayfish and Himalayan balsam The obtained results indicate that there are few avenues through which invasive ecosystem engineers can influence river bank processes. While many uncertainties remain, due to the intrinsic complexity of river ecosystems, a multitude of anthropogenic stressors that they are increasingly subjected to and a wide array of ecosystem services that rivers provide to people, it is important to consider the role of invasive ecosystem engineers in river management practices. on river banks. The work included analyses and development of conceptual models for the understanding of invasive ecosystem engineers, followed by four research chapters aimed at answering specific questions. A study of signal crayfish impact is primarily focused on the impact of burrows that crayfish dig as shelter and their influence on riverbank erosion. The interaction between habitat characteristics, the occurrence of burrows and erosion is analysed on three different levels of spatial scale: bank section in reach, reach in the catchment and bank section in the catchment. Bank section in reach survey (Chapter 4) focused on a reach heavily impacted by crayfish burrowing on the River Windrush, UK, in order to study the maximum effect of burrowing. Also, smaller spatial extent enabled detailed study of three sets of variables as well as an assessment of the impact that signal crayfish population density has on burrowing. Reach in catchment spatial scale expanded the survey to cover 103 river reaches in the Thames catchment and was based on a combination of habitat information from publicly available online data sets, primarily the River Habitat Survey database and rapid field surveys that recorded burrows and erosion. Bank section in catchment-scale was based on the same 103 sites, but the main focus of field observations were ten metres long bank sections for which habitat, burrows and erosion information were collected. Overall, burrowed banks were more likely to be characterised by cohesive bank material, steeper bank profiles with large areas of bare bank face, often on outer bend locations and were associated with bank profiles with signs of erosion. There were indications that signal crayfish burrowing is contributing to the river bank erosion, but no conclusive results have been made. Study of the impact of the Himalayan balsam was undertaken on eight sites at the River Brenta in Italy and it was focused on three main aspects. Firstly it was established that extent of Himalayan balsam domination over native vegetation varies widely depending on the habitat conditions and native plants encountered. Secondly, it was established that there are no conclusive differences in the extent of erosion and deposition on transects covered by native vegetation and Himalayan balsam. Thirdly, measurement of traits of individual plants showed significant differences in traits of individual plants that are known to have consequences for river bank erosion and deposition.

Plankton play a key role in regulating nutrient and carbon cycles in freshwater ecosystems. The uptake and processing of nutrients in planktonic biomass are highly sensitive to changes in the environment, such as alterations in the availability of limiting nutrients, increasing temperature due to climate change, and changes to the composition of interacting species. The focus of this thesis is to use a variety of experimental and theoretical methods to assess and predict the impact of multiple perturbations on community structure, dynamics and ecosystem function, with a particular focus on interactions between phytoplankton and their consumers (zooplankton). Increases in both temperature and phytoplankton species diversity independently decreased CO2 concentrations when the number of non-resource species (those inedible to the zooplankton) were high. Using structural equation modeling I show that the effect is indirect, resulting largely from the positive impacts on total biomass of phytoplankton. Phytoplankton are limited by a range of resources, and differences in the functional traits used to utilize light and nutrients can explain the distributions of species under different temperature regimes. I found that under light and nitrogen limitation, resource requirements are generally lowest at intermediate temperatures, and that changes in temperature may therefore alter the competitive hierarchy amongst species. Using the model freshwater phytoplankton Chlamydomonas reinhardtii, I also find that previous selection environments govern future competitive abilities in phytoplankton. Adaptation to a high salt and low nutrient stress increases competitive ability under light limited conditions, indicating a strong dependency of selection environment for overall competitiveness. This thesis provides a mechanistic insight into the role of diverse plankton communities for community dynamics and ecosystem functioning.

The systematic relationship of two species of the Peromyscus truei group (P. truei and P. difficilis) was analysed through the application of starch gel electrophoresis, numerical taxonomy, and chromosomal techiques. Of 20 loci examined, 11 were monomorphic in all populations, two exhibited variation in only two populations, and seven loci were polymorphic in two or more populations. The mean number of polymorphic loci per population was 0.186, the mean number of polymorphic loci per individual was 0.024, and the proportion of loci heterozygous per individual was 2.4%. Chromosomal forms of P. truei, P. t. gentilis (FN 54) and P. t. truei (FN 62), and P. difficilis, P. d. petricola (FN 56) and P. d. nasutus (FN 58), were consistent for their karyotypes throughout their geographic ranges. No chromosomal hybrids were detected. Numerical analysis of morphological characters and similarity values based on allelic frequencies utilizing Roger's coefficient (S) demonstrated a distinct seperation of karyotypic forms of P. truei (S = 0.902) and P. difficilis (S = 0.924) and were below the mean value of S for conspecifics (S = 0.950). All data indicates that each chromosomal form of the P. truei group examined represents four distinct species. The oldest available name for chromosomal forms of P. true with a fundamental number of 62 is Peromyscus truei Shufeldt (1885) and the oldest available name for chromosomal forms with a fundamental number of 54 is Peromyscus gratus Merriam (1898). The oldest available name for chromosomal forms of P. difficils with a fundamental number of 58 is PeromYSCus nasutus Allen (1891) and the oldest available name for chromosomal forms with a fundamental number of 56 is Peromyscus difficilis Allen (1891).

Submitted by Jorge Cativo (jcativo@gmail.com) on 2018-05-23T22:12:32Z No. of bitstreams: 2 VariedadesdeespeciesdeorquideasencontradasnaAmazoniaClaudiaLimaCabral.pdf: 87962 bytes, checksum: 67b14c047c6db4395f97de1f2c5a1203 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-23T22:12:32Z (GMT). No. of bitstreams: 2 VariedadesdeespeciesdeorquideasencontradasnaAmazoniaClaudiaLimaCabral.pdf: 87962 bytes, checksum: 67b14c047c6db4395f97de1f2c5a1203 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-02 / Dichaea bragae is a pendulous plant, small, reaching five centimeters in length, the flower reaches five centimeters and has a structure called the lip, which is a modified petal. It is a landing structure of insect pollinators. The flower of Anathalis manausesis, according to the researcher, is only 3 millimeters (mm) and its leaf is less than 1 centimeter (cm). It is considered the smallest of the species already described. Brazil registers more than three thousand types of orchids. In Amazonas, there are about 300. According to the biologist, Amazonian orchids have characteristics similar to those of other regions. They can be found mainly in the so-called Amazonian campinaranas, areas with sandy soils, and also in the canopy of trees. Orchids have a preference, a need for light, a diffuse light. And the treetops are an ideal environment for them. In a dense ombrophilous forest, which is a tall forest, with trees up to 25 or 30 meters, you can hardly see orchids. / La Dichaea bragae es una planta péndula, pequeña, llegando a cinco centímetros de longitud, la flor llega a cinco centímetros y presenta una estructura llamada labelo, que es un pétalo modificado. Es una estructura de aterrizaje de insectos polinizadores. La flor de la Anathalis manausesis, de acuerdo con el investigador, tiene sólo 3 milímetros (mm) y su hoja mide menos de 1 centímetro (cm). Se considera la menor de las especies ya descritas. Brasil registra más de tres mil tipos de orquídeas. En el Amazonas, son cerca de 300. De acuerdo con el biólogo, las orquídeas de la amazonia tienen características similares a las de otras regiones. Se pueden encontrar, principalmente, en las llamadas campinaranas amazónicas, áreas con suelos arenosos, y también en la copa de árboles. Las orquídeas tienen preferencia, una necesidad de luz, una luz difusa. Y la copa de los árboles es un ambiente ideal para ellas. En un bosque de ombrófilo denso, que es un bosque alto, con árboles de hasta 25 o 30 metros, difícilmente usted puede ver orquídeas. / A Dichaea bragae é uma planta pêndula, pequena, chegando a cinco centímetros de comprimento, a flor chega a cinco centímetros e apresenta uma estrutura chamada labelo, que é uma pétala modificada. É uma estrutura de pouso de insetos polinizadores. Já a flor da Anathalis manausesis, de acordo com o pesquisador, tem apenas 3 milímetros (mm) e sua folha mede menos de 1 centímetro (cm). Ela é considerada a menor das espécies já descritas. o Brasil registra mais de três mil tipos de orquídeas. No Amazonas, são cerca de 300. De acordo com o biólogo, as orquídeas da amazônia têm características semelhantes às de outras regiões. Elas podem ser encontradas, principalmente, nas chamadas campinaranas amazônicas, áreas com solos arenosos, e também na copa de árvores. Orquídeas têm preferência, uma necessidade de luz, uma luz difusa. E a copa das árvores é um ambiente ideal para elas. Em uma floresta de ombrófila densa, que é uma floresta alta, com árvores de até 25 ou 30 metros, dificilmente você consegue enxergar orquídeas

Philosophiae Doctor - PhD / Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain. Although the etiology of PD is not completely known, it is believed to involve an association of various genetic, cellular, and environmental factors that individually or simultaneously advance neuronal degeneration. Neurotoxins such as 1-methyl-4-phenylpyridinium (MPP+) and 6-hydroxydopamine (6-OHDA) have been widely used to investigate distinct underlying mechanisms involved in the pathogenesis of PD. Presently, treatment options for PD are limited, as the available drugs are mainly focused on alleviating symptoms with limited ability to prevent disease progression. Accordingly, there is an increase in the use of natural compounds/products as potential neuroprotective agents. These neuroprotective treatments are believed to intervene in some stages in the pathogenesis of PD to suppress possible mechanisms of dopaminergic neuronal death such as apoptosis, mitochondrial dysfunction, oxidative stress, disturbances of calcium homeostasis, inflammation and autophagy. Thus, novel protective strategies for PD may be designed by targeting these mechanisms or intracellular signaling cascades that participate in PD pathogenesis.

Philosophiae Doctor - PhD / In the marine environment, penguins have been described as curators and serve a critical role in ecological balance. The African penguin (Spheniscus demersus) has undergone a rapid population decline, mainly due to disturbances in their natural habitat. The African penguin was up-listed from vulnerable to endangered on the IUCN Red List for Threatened Species in 2010 and thus urgent conservation action is required. Integral to long-term conservation action of any species is a basic knowledge of its reproductive biology, which is currently lacking for African penguins. The main aim of this investigation was to evaluate techniques for the collection of semen in African penguin and to determine sperm quality in order to cryopreserve sperm for in vitro fertilization (IVF) purposes of captive and wild populations. Semen was collected once a week during two breeding seasons from two captive African penguins. Ejaculates (n=51) were obtained over two breeding seasons (Jan-Feb and Jun-Oct) and evaluated for semen volume, sperm concentration, sperm vitality, sperm motility and sperm morphology. In addition twelve (six females and six males, n=4 were breeding pairs) captive African penguins were monitored for hormone (estradiol, testosterone, progesterone) levels prior to and after the egg-laying period.