Passive acoustics provides a powerful tool for marine mammal research and mitigation of the risk posed by high energy anthropogenic acoustic activities through monitoring animal positions. Animal vocalisations can be detected and utilised in poor visibility conditions and while animals are dived. Marine mammal research is often conducted on restricted financial budgets by non-government organisations and academic institutions from boats or ships towing hydrophone arrays often comprising only two elements. The arrival time-delay of the acoustic wavefront from the vocalising animals across the array aperture is computed, often using freely available software, and typically regarded as the bearing of the animal to the array. This methodology is limited as it provides no ranging information and, until a boat manoeuvre is performed, whether the animal is to the left or right of the array remains ambiguous. Methods of determining range that have been suggested either negate the fact the animal is moving, rely on robust detection of acoustic reflections, rely on accurate equipment calibration and knowledge of the animal’s orientation or require modification of hydrophone equipment. There is a clear need to develop an improved method of estimating animal position as relative bearing, range and elevation to a hydrophone array or boat based on time-delay measurements. To avoid the costs of upgrading hydrophone arrays, and potentially the size of the vessels required to tow them, a software solution is desirable. This thesis proposes that the source location be modelled as a probability density function and that the source location is estimated as the mean. This is developed into a practical method using particle filters to track sperm whales. Sperm whales are the ideal subject species for this kind of development because the high sound pressure levels of their impulsive vocalisations (up to 236 dB re 1 μPa) makes them relatively simple to detect. Simulation tracking results demonstrate particle filters are capable of tracking a manoeuvring target using time-delay measurements. Tracking results for real data are presented and compared to the pseudotrack reconstructed from a tag equipped with accelerometers, magnetometers, a depth sensor and an acoustic recorder placed on the subject animal. For the majority of datasets the animal is tracked to a position relatively close to the surface sighting position. Sperm whales are typically encountered in groups, therefore a viable tracking solution needs to be capable of tracking multiple animals. A multiple hypothesis tracking method is proposed and tested for associating received vocalisations with animals, whereby vocalisations are correctly associated for periods exceeding 15 minutes

The concept of a particular atom, compound or group of compounds being transformed by geochemical, anthropogenic and biological processes on a global scale is not new: the cycling of water and carbon and nitrogen have been recognised in biology and geography. A similar cycle can be constructed for sulphur, which at the most basic level is much like that of carbon. The primary difference is that unlike carbon dioxide (C02) and photosynthesis, biological agents do not play as great a part in the removal of sulphur compounds from the atmosphere to a terrestrial form.

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.

Membrane proteins in Xenopus laevis embryos were analysed on 1- and 2-dimensional gels. Proteins showing temporal variation in their expression in the membrane during Xenopus development were detected. The overall range of membrane proteins present between fertilisation and late neurula stage embryos was found to stay essentially constant, with few proteins showing temporal variation. Microinjection of 30 S-methionine into Xenopus laevis embryos was used to investigate membrane protein synthesis. Dramatic changes in the composition of proteins synthesised during Xenopus laevis early development were noted, with most significant changes observed at the gastrula stage following the mid-blastula transition. Cell membrane variation in Xenopus laevis embryos was studied using cell surface labelling with 125 Iodine. Two proteins specific to labelling of disaggregated embryos were detected and these are thought to be specific to intercellular membranes. Cell surface labelling with 125 Iodine was also used to characterise overall changes in the cell membrane during Xenopus laevis early development. Histo- autoradiography of 125 Iodine surface labelled embryos was used to confirm the origin of cleavage furrow membrane in the dividing embryo, and the source of ciliated cells from the double layered epidermis in Xenopus laevis neurulae. 2B12, a monoclonal antibody raised against adult Xenopus laevis brain tissue, was characterised on embryo and tissue sections using indirect immunofluoresence. Biochemical analysis of 2B12 activity has indicated that the antigen may be a ganglioside, specific to myelin and other nervous tissue membrane.

Homologues of developmentally important regulatory genes from other species have been found to be expressed in early amphibian development. The Drosophila dorso-ventral polarity .gene, dorsal, is involved in the formation of ventral structures and dorsal- mutants arise from a default state where only dorsal structures are formed. A Xenopus homologue of dorsal may play a crucial role in interpreting some of the earliest embryonic signals.

The main aim of this work was to identify the important cis-acting regulatory sequences, and the trans-acting factors with which they interact, which are required for the tissue-specific expression of the Xenopus borealis skeletal actin gene. All sequences necessary and sufficient for the correct spatial and temporal expression of the Xenopus borealis skeletal actin gene are located in a 156 bp fragment of the gene that spans from nucleotide residues -197 to -42 in its promoter. This region of the skeletal actin promoter contains three imperfect repeats of a CArG sequence motif that has been demonstrated to be important in the expression of other sarcomeric actin genes. Deletion analysis of the promoter of the Xenopus borealis skeletal actin gene, using Xenopus micro-injection techniques as a transient assay system for promoter activity, have identified that CArG box3 is essential for skeletal actin gene expression. By using band shift assays I have demonstrated that, under my assay conditions, CArG box2 is unable to bind any proteins in vitro . Conversely, the CArG boxl sequence exhibits two binding activities on band shift analysis. One of these is antigenically related to the transcription factor SRF, whilst the second appears to be distinct from this protein. CArG box3 also interacts with a protein in vitro. Although this sequence exhibits a similar shift to that of the CArG boxl/SRF complex on band shift analysis, my experiments suggest that this protein is distinct from SRF. A combination of the CArG boxl and CArG box3 motifs is unable to confer muscle-specific gene expression on a heterologous promoter. Furthermore, I have identified an upstream regulatory element (URE) in the Xenopus borealis skeletal actin gene promoter that spans from nucleotides -197 to -167 that is required for the expression of the gene, at least when sequences between nucleotide -42 and +28 are absent. The URE of the Xenopus borealis skeletal actin gene is capable of interacting with a trans-acting factor(s) in vitro. In addition to this a further region of the gene which spans from nucleotide residues -83 to -42 is also capable of interacting with a factor(s) in vitro. The mechanisms by which these multiple regulatory elements control the tissue-specific expression of the Xenopus borealis skeletal actin gene will be discussed.

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.

Oystercatchers Haematopus ostralegus and cockles Cerastoderma edule were studied with the aim of understanding the behaviour of predators and the consequences which this behaviour has on the cockle population. At Traeth Melynog, Anglesey, the cockle density declined down the shore and those at the bottom were larger, older and heavier than those at the top. This pattern was caused by the spat settling at the top of the shore combined with downshore movement of some cockles. As a consequence, both flesh content and size were correlated with prey density. The profitability (flesh eaten per minute handling time) of cockles increased with their size. According to optimal foraging theory, these larger ones should therefore have been preferred, and this proved to be so. The rate at which oystercatchers ate cockles followed a type II functional response. The plateau was not caused solely by handling time, nor were satiation or interference important. Analysis of the functional responses of other birds feeding on one prey species showed that in each case the behaviour also conformed with a type II distribution yet neither handling time nor satiation appeared responsible. To account for this, a theoretical model was developed which generates type II functional responses from optimal foraging theory. Another model was developed which predicts the aggregative numerical response for a given level of interference. Because of correlations between density, size and flesh content within the cockle population at I Traeth Melynog, this model could not be directly applied to the data. But the basic assumption of the model - that oystercatchers obeyed the ideal free distribution - could be tested. It gave a poor fit to the data. There was little measurable interference between oystercatchers feeding on cockles. The number of oystercatchers on the Ribble fluctuated in parallel with the cockle population. Much of this change appeared to be due to an influx of young birds. This suggests that young birds seek a suitable estuary whilst adults tend to return to the one found whilst young. Thus the change in oystercatcher numbers was an aggregative numerical response rather than a population numerical response. Due to correlations within the cockle population at Traeth Melynog, profitability reached a maximum value at 25-100 cockles per m2. Therefore the oystercatchers concentrated their feeding at these relatively low cockle densities. As a result, cockle mortality due to predation by oystercatchers was inversely density dependent over most of the range of densities. However, since cockle movement took place, this pattern of mortality could not be detected in the cockle population.

No description available.