No description available.

No description available.

Feeding the extract of the seaweed Ascophyllum nodosum (ANOD) has been shown to mediate the response of livestock to certain environmental stressors. To determine if feeding ANOD is useful in alleviating handling and transport stress, two trials were conducted. The dose response trial was conducted to determine at which rate ANOD should be fed to obtain beneficial results. Forty-four lambs received ANOD at either 0 (control), 0.5, 1, or 2% of dry matter intake per day (approximately 0, 0.25, 0.5, and 1 g/kg of body wt per day). Sheep were administered ANOD twice daily for 14d. After 14d of supplementation, IgG and IgM antibody response to ovalbumin was reduced by ANOD. The sheep fed at the 2% rate had a narrower range of body temperature during transport than controls. The 2% rate also had lower body temperatures than the controls during times when the thermal heat index was above 80. The sheep fed the 2% rate had lower cortisol and aldosterone concentrations during walking and transport compared to the controls. Post transport, sheep supplemented at the 1 or 2% rates were less dehydrated as indicated by plasma chemistry profiles andelectrolyte concentrations. In a subsequent trial, the major components of the ANOD (fucoidan, salt, and betaine) were fed to determine which, if any, were responsible for the treatment effects in the dose response trial. After 14d supplementation, the salt and ANOD sheep had a depressed IgG and IgM antibody response to ovalbumin and an increase in white blood cell counts and lymphocyte numbers compared to controls. The ANOD sheep were generally lower in body temperature than the other treatments during transport. The ANOD and salt sheep had lower cortisol concentrations compared to controls. At the end of transport, sheep supplemented with ANOD or salt had lower electrolyte concentrations than control sheep. Supplementation with ANOD was associated with lowered body temperature; however, it also suppressed antibody titer which could leave animals susceptible to bacterial infection. The lowered antibody production is of concern and needs further study before ANOD can be recommended as a useful stress management tool.

No description available.

No description available.

No description available.

Seaweeds fulfil many of the criteria regarded as being important for a good biomonitor. They are known to accumulate trace metals and the concentration of these metals measured in the thalli of native populations has been related to the level of contamination in the surrounding water. However, this passive biomonitoring approach has been of limited use and the relationship between the concentration of metal in the seaweed and that in the surrounding environment is not always apparent. The aim of this study was to investigate the response of the rhodophyte Gracilariopsis longissima to copper exposure, in the laboratory and field, in order to increase the understanding of the toxic effects of the metal and ultimately to assess the potential of this species as a biomonitor of trace metal pollution. A series of comparative physiological experiments were performed to assess the relative effects of copper on the growth and physiology of the species. Growth was reduced at significantly lower levels of copper {l2µg Lˉ¹) than any other physiological parameter measured. Photosynthesis, as measured by oxygen evolution and fluorescence measurements, was only reduced at high copper treatments (250-400µg Lˉ¹). This coincided with the actual shrinkage of the algal material, increased ion leakage and loss of pigmentation. One possible explanation for the uncoupling of growth from photosynthesis was investigated and rejected. Copper accumulated in the thallus of exposed material as a linear function of the copper treatment. Algal material was able to recover, in terms of growth, following exposure to elevated levels of copper. This recovery coincided with a significant release of copper from the thalli and a resulting increase of copper in the recovery media. This discovery suggests that the accumulated metal is not irreversibly bound to the thalli, and has important implications in terms of using the species as a biomonitor of copper pollution. Populations of G. longissima collected from sites known to differ in trace metal contamination were exposed to copper in a series of laboratory based experiments to measure the effect of the metal on their growth. Exposure to elevated levels of copper significantly reduced growth. However, no major difference existed between the response of the populations compared. Possible explanations for this are discussed. Considerable inter and intra-individual variability was found to exist within populations of G. longissima and causes and implications of this mostly overlooked source of variation are highlighted. A field method of active biomonitoring using reciprocally transplanted individuals was developed as an alternative to passive biomonitoring and was found to offer a number of distinct advantages. In particular, the ability to observe responses to copper in areas where no natural population occurred was explored at a highly contaminated site.

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The aims of this project were to investigate the cellular stress response (CSR) in Enteromorpha spp. and assess the potential of the Stress-70 protein (an indicator of the CSR) as a biomarker of pollutant exposure and acquired tolerance in Enteromorpha spp., compared with conventional physiological endpoints of toxicity. Cross-reactivity of a commercial Stress-70 antibody with E. intestinalis proteins was determined and used to develop an assay for Stress-70. Using this assay E. intestinalis was found to exhibit a typical heat shock response. Stress-70 proved to be a relatively insensitive biomarker of copper exposure and did not appear to be involved in copper tolerance, the genetic basis of which was investigated by growing E. intestinalis using a novel culturing technique. Although growth was variable, it provided a simple, consistent and sensitive measure of copper toxicity. The chlorophyll fluorescence parameter Fv/Fm was insensitive to copper exposure. Nutrient limitation enhanced copper toxicity and significantly impaired growth, Fv/Fm and Stress-70 production in E. intestinalis. In both copper ‘sensitive’ and ‘tolerant’ E. intestinalis, copper exposure did not affect the ability to raise a heat shock response. In ‘sensitive’ algae, copper and heat shock were additive stressors, with heat shock acting as a stronger inducer of Stress-70. Only heat shock affected 'tolerant' algae. Zinc was less toxic than copper but in contrast to copper studies, Stress-70 was a relatively sensitive indicator of zinc exposure, compared to Fv/Fm and growth. Studies of triazine herbicides revealed that on a molarity basis, Irgarol 1051 was more toxic to E. intestinalis than atrazine. Fv/Fm and growth were strongly affected by Irgarol exposure, but Stress-70 levels were unaltered by exposure to the herbicide. Fv/Fm and Stress-70 were poor in situ biomarkers of pollution, but another chlorophyll fluorescence parameter - complementary area - appeared to correlate with levels of organic pollution. Overall, Stress-70 was found not to be a useful biomarker of exposure to copper or triazines in E. intestinalis, or in situ pollution. However, the Stress-70 assay developed has a number of alternative applications and Enteromorpha spp. were deemed to be potentially useful in pollution monitoring with the selection of suitable biomarker responses.

No description available.