Collections of Saprolegniaceous fungi were made from diseased tropical fish. Nineteen strains, representing three fungal genera (<u>Saprolegnia</u>, <u>Achlya</u> and <u>Pythium</u>), were isolated from 11 fish species. Due to difficulty in inducing sexual fruiting, only two strains were identified to species; both of these being <u>A. americana</u>. Laboratory infection studies revealed the ability of strains of each different fungus to infect five selected tropical fish species. <u>Saprolegnia</u> sp. and <u>A. americana</u> proved to be more vigorous and lethal pathogens than <u>Pythium</u> sp. No indications of host specificity were evident. All chemicals tested (Table 4) showed definite fungicidal abilities. No effective fungicidal concentration of the chemicals tested would permit sustained fish culturing. Malachite green was the most effective fungicide tested, being functional in concentrations as low as 2 ppm. / Master of Science

Les études comparatives réalisées selon un large éventail spatio-temporel sont fort utiles pour améliorer notre compréhension de l’état de santé des populations d'animaux sauvages. Ce mémoire vise à étudier le parasitisme chez le caribou migrateur (Rangifer tarandus) en Amérique du Nord et au Groenland. Un total de 1507 caribous a été échantillonné à travers douze troupeaux pour sept de leurs principaux macroparasites. L’intensité de Hypoderma tarandi augmentait avec l’âge chez les mâles alors que le contraire a été observé chez les femelles. La prévalence de Fascioloides magna, Taenia hydatigena et Cephenemyia trompe était plus élevée chez les adultes que chez les jeunes. La prévalence et l’intensité de F. magna et la prévalence de T. hydatigena étaient plus élevées lorsque la taille des troupeaux de caribous était élevée. Cette recherche fournit la première étude comparative de ces parasites helminthes et arthropodes chez le caribou migrateur à large échelle spatio-temporelle. / Comparative studies across time and geographical regions are useful to improve our understanding of the health of wildlife populations. Our goal was to study parasitism in migratory caribou (Rangifer tarandus) of North America and Greenland. A total of 1507 caribou were sampled across twelve herds to assess seven of their main macroparasites. Intensity of Hypoderma tarandi increased with age for males while the opposite was observed in females. Prevalence of Fascioloides magna, Taenia hydatigena, and Cephenemyia trompe was higher in adults than in calves. Prevalence and intensity of F. magna and prevalence of T. hydatigena were higher at high caribou herd sizes than at low herd sizes. Our research provides the first comparative survey of these helminth and arthropod parasites of caribou across a broad spatial-temporal range.

No description available.

Call number: LD2668 .T4 1937 H63 / Master of Science

Call number: LD2668 .T4 1979 S73 / Master of Science

Call number: LD2668 .R4 1957 E47 / Master of Science / Entomology

Introduction Le Québec accueille 50 000 immigrants annuellement dont 30 % viennent d’Afrique et 27 % d’Asie. Dans les dix dernières années, 200 à 600 enfants ont été adoptés annuellement, majoritairement de l’Asie. Plusieurs régions d’origine des immigrants sont endémiques pour des parasites. C’est pourquoi l’immigration influence fortement l’épidémiologie de ces maladies. La giardiase, la filariose, la schistosomiase, la strongyloïdose et la malaria sont les plus prévalentes. Il existe peu de données sur les maladies parasitaires chez les immigrants au Québec. Cette étude vise à décrire l’épidémiologie de cette problématique dans la province. Méthode Une étude descriptive transversale a été privilégiée. Les immigrants ayant consulté au centre des maladies tropicales de l’Université McGill et les enfants de la clinique d’adoption de l’hôpital Maisonneuve-Rosemont ont été ciblés. Une grille standardisée a été utilisée pour la collecte des données dans la base de données de GeoSentinel et les dossiers médicaux. Des analyses descriptives et inférentielles fournissent un profil des immigrants atteints et des facteurs associés. Résultats Au moins un parasite se trouve chez 32 % (202/638) des immigrants à l’étude. Les parasitoses les plus prévalentes chez ces cas sont la strongyloïdose (28%), la filariose (21%), la schistosomiase (17%), et la malaria (12%). Le tiers des cas sont des demandeurs d’asile et 43 % (86/202) viennent de l’Afrique subsaharienne. Une proportion élevée d’infection, 50 % (27/56), se trouve chez les Haïtiens. Chez 15 % (73/499) des enfants adoptés, on trouve au moins un parasite; la giardiase et la strongyloïdose sont les plus prévalentes. La majorité (292/499) des enfants à l’étude viennent de la Chine et 69 % (22/32) des enfants Haïtiens sont infectés par des parasites. Discussion et conclusion La littérature appuie nos résultats. La population immigrante est en croissance au Québec ce qui est une des richesses de la province. Par contre, c’est une population qui est vulnérable au niveau de la santé. Environ 1/3 des immigrants et 1/6 des enfants adoptés sont atteints par des parasitoses. Plus de la moitié (57 %) des immigrants atteints sont infectés par des parasites qui ont des conséquences importantes. Des interventions ciblant cette population sont recommandées afin de diminuer ce fardeau.

Submitted in partial fulfillment of the academic requirements for the degree of Master of Technology: Biotechnology, 2009. / Production of numerous biotechnologically-important products such as threonine is based on cultivation of bacterial cultures. Infection of these bacterial cultures by bacteriophages has a detrimental effect in the production of these bioproducts. Despite this, most people controlling these bioprocesses do not recognize the early signs of bacteriophage infection. SA Bioproducts (Ply) Ltd was no exception and has suffered tremendous loss of production time after bacteriophages infected threonine producing E. coli strain B. This study was aimed at developing assays to control and prevent bacteriophage infection at this company. These included determining the source of phages by monitoring the process plant environment, optimising the detection and enumeration methods so as to monitor the levels of bacteriophages in the environment, identification of bacteriophages in order to determine the number of bacteriophages capable of infection threonine producing E. coli strain B, treatment and of phages, and possible prevention of phage infection. Adam's DAL method was very efficient at detecting phages in the samples collected at various areas (sumps, odour scrubber, process water, and soil) around the plant for 16 weeks. High levels of phages were found in the sumps and this was identified as the source of infection. Samples collected were grouped together according to their source. The samples were enriched and purified in order to characterise them. The prevalent phage in all samples was identified as a T1-like phage. Bacterial strains that grew on the plate in the presence of phages were assumed to be resistant to phages or contained lysogenic phages which would explain the new lytic cycles that were observed whenever these resistant strains were used for production. UV light, green v indicator plates, and a mutagen (Mitomycin C) were used to detect Iysogens. Mitomycin C at 1 IJg/ml was found to be most effective in detecting lysogenic phages. This was shown by new plaque forming units that were visible on the DAL plates. Temperature (heat), chemicals, and inhibitors (vitamins) were investigated as strategies for prevention and treatment of bacteriophage infection. Bacteriophage samples were exposed to 70, 80, 100, and 120°C. At these temperatures pfu counts in the samples were reduced significantly. At 120°C there was a complete inactivation of bacteriophages within 30 minutes. Chemicals investigated such as sodium hydroxide and Albrom 100T were capable of complete deactivation of bacteriophages at a very low concentration (0.1%). Therefore, these chemicals can be used to clean the plant area and sumps. Vitamins C, K and E solutions were investigated to determine their inhibitory effect on bacteriophages. Vitamin C, K and E reduced pfu counts by 3, 2, and 4 logs, respectively. Therefore vitamin C and E solutions were mixed and to determine if mixing them would enhance their inactivation capabilities. This resulted in a reduction greater than 9 logs of phage in the sample (from 7.7 x 109 to 3 pfu/ml). The host bacterium was also exposed to this mixture to determine effect of the vitamin mixture on its growth. It was found that there was no effect exerted by this mixture on the host bacteria. This proved to be an ideal mixture for combating phages during fermentation. However, vitamin E is not cost effective for co-feeding in 200 m' fermenters, and therefore vitamin C solution was a cost-effective alternative. It was concluded that bacteriophage contaminated bioprocessing plant should be properly cleaned using a combination of heat and chemicals. Bacteriophage infection should be prevented by employing inhibitors.

Severe population bottlenecks and the small size of many remnant habitats may render many bird populations prone to extinction from disease outbreaks. Bottlenecks may increase inbreeding which in turn may result in a low diversity of resistance and an immune system that is impaired or defective. Thus, bottlenecked populations may be less immunocompetent and more vulnerable to microbiological and parasitic perturbations. Few studies have assessed the effect of bottlenecks on the immunocompetence of birds. In this study, I used twelve saddleback (Philesturnus carunculatus) and two New Zealand robin (Petroica a. australis) populations, to determine if the severe bottlenecks reduce the immunocompetence of birds. When I experimentally challenged the immune system of two robin populations I found that despite the two populations having similar parasite loads, robins from the severely bottlenecked Motuara Island population exhibited a significantly lower T-cell mediated immune response than the source population (Nukuwaiata Island) suggesting that birds passing through severe population bottlenecks have a compromised immunocompetence. In the saddleback, severe bottlenecks, as well as high population densities and small island size, lead to individuals exhibiting higher stress levels and feather mite loads and lower immune function, as was evident by lower lymphocyte counts. I did not find levels of fluctuating asymmetry of saddlebacks to be directly influenced by bottleneck size. However, I did find that individuals with higher levels of fluctuating asymmetry had higher loads of hippoboscid flies and lower loads of coccidia suggesting a possible trade-off between growth and immune function. In contrast to previous studies looking at behavioural secondary sexual traits, I found no effect of founder number on the size of wattles in saddleback. I did however demonstrate that wattle size reflected the level of immune function in females as well as males, suggesting that females play a far greater role in offspring fitness than has been appreciated in traditional theories of sexual selection. Overall, my results indicate that severe bottlenecks can lead to reductions in immunocompetence in the resulting populations, especially in those populations that pass through the most severe bottlenecks. Based on the evidence from my thesis, I recommend conservation managers should aim to use at least 90 individuals to found new populations in order to reduce the deleterious effects of bottlenecks on immune function. If the costs of population bottlenecks and inbreeding are to be avoided, conservationists must adequately address the role of genetic factors in susceptibility to disease, and work towards minimising the risk of severe population bottlenecks in the management of endangered birds

I investigated parasitic infection and immunocompetence in populations of introduced bird species in New Zealand (NZ) that had experienced a range of population bottlenecks (11-808 individuals), and compared these parameters to non-bottlenecked conspecifics in the United Kingdom (UK). My aims were two-fold; firstly to assess if population bottlenecks are linked to increased parasite loads and/or decreased immunocompetence, and secondly, to assess at what severity of bottleneck these effects become evident. I found that ectoparasite load (chewing lice, Order: Phthiraptera, Sub-Orders: Amblycera & Ischnocera) was significantly higher in the more severely bottlenecked species in NZ than in the UK, whilst this difference became non-significant at more moderate bottlenecks. The difference was mainly driven by the Sub-Order Amblycera. The prevalence of avian malaria (Plasmodium spp.) was significantly negatively correlated to bottleneck size within NZ, after controlling for body mass. Total leucocyte and differential lymphocyte counts were elevated in the less bottlenecked species that were infected with malaria, whilst the populations at the more severe end of the bottleneck spectrum did not exhibit such a response. Furthermore, heterophil/lymphocyte (HL) ratio (a parameter used as an indicator of environmental and/or immunological stress), was significantly raised in the more bottlenecked species when compared to their UK counterparts, and this difference was correlated with the size of the bottleneck. Immunocompetence was further assessed by the experimental challenge of six introduced birds species in NZ with the mitogen phytohaemagglutinin (PHA). Immune response to PHA was significantly correlated to bottleneck size, but in the opposite direction to that predicted; immune response was greater in the more bottlenecked species. However, this may be an indication of increased investment in immunity, due to increased parasite and pathogen pressure or differential investment in varying components of the immune system. Finally, the immune response to PHA was compared in nestlings of two species that had experienced very different bottlenecks (70 vs. 653). After controlling for ectoparasitic infestation, I found no difference between the two species; however, this finding may be confounded by interspecific competition. Overall, my findings suggest that more severe population bottlenecks may result in increased susceptibility to pathogens, and impact on the immune system. This has a number of implications for the development of conservation protocols, and future avenues of research are suggested.