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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Identificação de novos alérgenos de pólen do cajueiro (Anacardium occidentale L.) para auxílio no diagnóstico e futura otimização do tratamento / Identification of novel allergens of cashew pollen

Daniele Danella Figo 28 June 2017 (has links)
A polinose é uma rinite alérgica sazonal que acontece pela sensibilização por pólens. Possui periodicidade anual, repetindo-se os sintomas sempre na mesma época do ano. Clinicamente, é caracterizada por rinoconjuntivite e/ou asma brônquica. A imunoterapia alérgeno-específica é o único tratamento capaz de modificar a evolução natural da doença, porém, depende fundamentalmente da correta identificação do alérgeno responsável. Diante disso e do número de pacientes que procuram o Ambulatório de Alergia da Universidade de Fortaleza com manifestações alérgicas exacerbadas na época de floração do cajueiro, o objetivo deste estudo foi produzir um extrato protéico a partir do pólen do cajueiro e identificar os alérgenos ainda não estudados presentes neste pólen. Doze pacientes residentes em Fortaleza, Nordeste do país, foram selecionados com base na história de rinite alérgica persistente e agravamento dos sintomas no momento da floração do cajueiro. Foi selecionado outro grupo com rinite alérgica que vive na mesma região, entretanto não apresenta relação clínica com a época de floração. Além disso, foram incluídos 5 indivíduos não-atópicos e expostos ao cajueiro como grupo controle. O soro desses pacientes foi testado em Western Blot 1D e 2D (WB) e as proteínas selecionadas foram submetidas à espectrometria de massas para identificação. Os epitopos foram preditos in silico pesquisando sequências detectadas por massa contra bases de dados de epítopos já conhecidos. Foi possível identificar alguns homólogos de alérgenos de outros pólens, como isoflavona redutase (Bet v 6), beta-1,3-glucanase (Ole e 9), proteína de choque térmico 70kDa (Cor a 10), além de outras proteínas que podem representar novos alergénios, tais como aminociclase, glutamina sintetase, fosfoglucomutase, ?-1,4-glucano-proteína-sintase, factor de alongamento 2 e biotina carboxilase, entre outros. A predição de epítopos revelou a possibilidade de reatividade cruzada com outros alérgenos de pólen conhecidos, tais como Phl p 4, Mal d 1, além de outros aeroalérgenos que também apareceram. Esta é a primeira descrição da alergia ao pólen do caju mostrando a reatividade específica de IgE no soros dos pacientes. A caracterização imunológica e estrutural de novos alérgenos, além de auxiliar no diagnóstico e tratamento de alergias não descritas, oferece ferramentas para prever epítopos e produzir moléculas hipoalergênicas nesta era da medicina de precisão / Pollinosis is a seasonal allergic rhinitis that develops due to pollens sensitization. Symptoms are manifested always in the same period of the year. Clinically, it is characterized by rhinoconjunctivitis and/or asthma. Allergen-specific immunotherapy is the only available treatment that can modify the natural course of the disease, however, it relies on the correct identification of the triggering allergen. Considering this and the number of patients attending the Allergy Clinic at University of Fortaleza with exacerbation of allergic symptoms during cashew flowering period, the aim of this study was to produce a protein extract from cashew tree pollen and identify the allergens not yet studied. Twelve patients living in Fortaleza, Northeast of country, were selected based on history of persistent allergic rhinitis and aggravation of symptoms at the time of cashew tree flowering. Another group living in the same region with allergic rhinitis without clinical relation with the flowering season was selected. Also 5 non-atopic subjects exposed to cashew tree were selected as a control group. The serum of these patients was tested for 1D and 2D Western Blotting (WB) and selected proteins were submitted to mass spectrometry for identification. Epitopes were predicted by in silico search comparing detected sequences against epitope databases. It was possible to identify some homologs of allergens from other pollens such as isoflavone reductase (Bet v 6), beta-1,3-glucanase (Ole e 9), heat shock protein 70kDa (Cor a 10), besides other proteins that might represent novel allergens, such aminociclase, glutamina sintetase, phosphoglucomutase, alpha-1,4-glucan-protein-synthase, elongation factor 2 and biotin carboxylase among others. The epitope prediction revealed the possibility of cross-reactivity with other known pollen allergens such as Phl p 4, Mal d 1 and other aeroallergens also appeared. This is the first description of cashew pollen allergy showing specific IgE reactivity of patients\' sera. The immunological and structural characterization of new allergens, besides aiding the diagnosis and treatment of non-described allergies, offers tools for predicting epitopes and producing hypoallergenic molecules in this era of precision medicine
172

Efeito da variação sazonal na produção de compostos ativos em Tithonia diversifolia (HEMSL) Gray, utilizando ensaio com microrganismos. / Effects of seasonal variation upon production of active compounds in tithonia diversifolia (HEMSL) Gray using microrganisms bioassay.

Paula Carolina de Simoni Cordeiro e Silva 13 August 2004 (has links)
A variação sazonal na produção de compostos secundários em Tithonia diversifolia (Hemsl) Gray foi investigada desde a primavera de 2002 até o inverno de 2003. Coletas bimensais foram realizadas com posterior extração e fracionamento do material vegetal (folhas e flores). As amostras foram monitoradas por CCD e analisadas quanto a atividade antimicrobiana contra Staphylococcus aureus, Escherichia coli, Salmonella choterasuis e Pseudomonas aeruginosa, pelo método de microplaca. Os perfis cromatográficos foral distintos para as diferentes épocas do ano, sendo evidenciada a presença de um grupo de substâncias em maior quantidade no mês de Abril de 2003 (outono), período de pré-florada desta espécie. Os extratos foram ativos para apenas dois microrganismos dentre os quatro testados. Algumas frações apresentaram CIM (concentração inibitória mínima) significativa (<1mg/mL). / The seasonal variation upon production of active compounds in Tithonia diversifolia (Hemsl) Gray was investigated from spring of 2002 until winter of 2003. Leaf samples were collected every three months for posterior extraction and analysis . The samples were monitored by Thin Layer Chromatography (TLC) and analyzed for anti-microbial activities on Staphylococcus aureus, Escherichia coli, Salmonella choterasuis and Pseudomonas aeruginosa, using micro-plate method. The TLC results showed a clear accumulation of active compounds during April . The extracts were active for only two microorganisms of a total of four studied.
173

Distribuição espacial e sazonalidade na borboleta Heliconius sara apseudes (Nymphalidae: Heliconiini) em uma floresta subtropical, no litoral do sudeste brasileiro / Spatial and seasonal distribution in the butterfly Heliconius sara apseudes (Nymphalidae: Heliconiini) in a subtropical forest in southeastern Brazilian coast

Sobral-Souza, Thadeu, 1985- 08 January 2011 (has links)
Orientador: Woodruff Whitman Benson / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-19T11:22:08Z (GMT). No. of bitstreams: 1 Sobral-Souza_Thadeu_M.pdf: 2228457 bytes, checksum: 1bafa7e233e5df09e117aab4299abb4c (MD5) Previous issue date: 2011 / Resumo: A ecologia de populações busca entender a variação na abundância das espécies no tempo e no espaço. Espécies que possuem ciclos de vida de curta duração, como a maior parte dos insetos, se tornam especialmente convenientes para essa finalidade. Este estudo examinou os padrões de abundância durante o ano 2009 de uma borboleta tropical próximo ao limite de sua distribuição geográfica, no sudeste do Brasil, em uma localidade subtropical. Neste trabalho, Heliconius sara apseudes foi estudada ao longo de uma estrada no Vale do Rio Quilombo, próximo à cidade de Santos, SP, Brasil, usando a metodologia de captura, marcação, liberação e recaptura (CMLR). Foram marcados 498 indivíduos de Heliconius sara (378 machos e 120 fêmeas) sendo 27,7% destes recapturados. Em 2009, indivíduos adultos de ambos os sexos apareceram na área na última semana de abril, sendo que os machos tiveram pico no início do mês de maio enquanto as fêmeas no fim do mês de abril. Os machos sempre foram muito mais abundantes que as fêmeas, independente da parte da estrada e da época do ano. Durante abril, plantas floridas, que servem de alimento para os adultos, eram abundantes. A abundância de adultos se manteve alta de abril a julho, seguido por um período de crescente raridade até sumir da área no início de outubro. Espacialmente, a abundância de H. sara foi maior na unidade demográfica 2 (final da estrada), próxima à serra, quando comparada com o início. A atividade, número de indivíduos voando, foi maior no final da estrada do que no início. Indivíduos marcados em diferentes segmentos da estrada se mostraram altamente residentes (96%). Os poucos que se dispersaram mais que 100 m (6 entre 138 recapturas) eram machos. O tempo médio de permanência no local foi de 18,8 dias para recapturas, com uma permanência máxima de 86 dias para machos e de 44 dias para fêmeas. Por fim, o comprimento da asa anterior (CAA) das fêmeas foi superior (2mm) ao dos machos. Diferente de H. sara de populações de Carajás - PA e de Linhares - ES que apresentam adultos ativos o ano inteiro, a população do Vale do Rio Quilombo aparentemente recruta de forma concentrada no mês de abril e some sem vestígios em outubro, ou mantêm populações baixas ou persiste em refúgios ecológicos sazonais / Abstract: Population ecology seeks to understand the variation in species abundance in time and space. Species that have life cycles of short duration, like most insects, is especially convenient for this purpose. This study examined patterns of abundance during one year in a tropical butterfly near the limit of geographical distribution, in southeastern Brazil, in a subtropical location. In this work, Heliconius sara apseudes was studied along of road in the Quilombo River Valley, near of Santos' city, SP, Brazil, using the method of capture, marking, release and recapture. 498 individuals were marked (378 males and 120 females) being 27.7% of those recaptured. In 2009, individuals of both sexes appeared in the last week of April, and the males had peaks in the beggining of the month of May while the females at the end of April. Males have always been much more abundant than females, regardless of road part and of the season. During April, flowering plants, which provide food for the adults were abundant. The abundance of adults remained high from April to July, followed by a period of rarity increasing until disappear in the area in early October. Spatially, the abundance of H. sara was higher in the second demographic unit (final Road), near the mountains, when compared with the beginning. The activity, number of individuals flying, was bigger in the end of the road than at the beginning. Individuals marked in different segments of the road were shown highly residents. The few that were dispersed more than 100 m (6 of 138 recaptures) were males. The average length of stay in place was 18.8 days for recaptures, with a maximum stay of 86 days for males and 44 days for females. Finally, the length of forewing of females was higher (2mm bigger) than the males. There was an increase in the size of the wings of males advancing years, perhaps due to better survival of larger butterflies. Different of H. sara populations further north that have active adults throughout the year, the population of Quilombo River Valley apparently recruits in concentrated form in April and disappears without a trace in October, or maintaining low populations or persisting in seasonal ecological refuges / Mestrado / Ecologia / Mestre em Ecologia
174

Seasonal predictability of North American coastal extratropical storm activity during the cold months

Pingree-Shippee, Katherine 01 May 2018 (has links)
Extratropical cyclones (ETCs) are major features of the weather in the mid- and high-latitudes and are often associated with hazardous conditions such as heavy precipitation, high winds, blizzard conditions, and flooding. Additionally, severe coastal damage and major local impacts, including inundation and erosion, can result from high waves and storm surge due to cyclone interaction with the ocean. Consequently, ETCs can have serious detrimental socio-economic impacts. The west and east coasts of North America are strongly influenced by ETC storm activity. These coastal regions are also host to many land-based, coastal, and maritime socio-economic sectors, all of which can experience strong adverse impacts from extratropical storm activity. Society would therefore benefit if variations in ETC storm activity could be predicted skilfully for the upcoming season. Skilful prediction would enable affected sectors to better anticipate, prepare for, manage, and respond to variations in storm activity and the associated risks. The overall objective of this dissertation is to determine the seasonal predictability of North American coastal extratropical storm activity during the cold months (3-month rolling seasons – OND, NDJ, DJF, JFM – during which storm activity is most frequent and intense) using Environment and Climate Change Canada’s Canadian Seasonal to Interannual Prediction System (CanSIPS). This dissertation describes research focused on three themes: 1.) reanalysis representation of North American coastal storm activity, 2.) potential predictability of storm activity and climate signal-storm activity relationships for the North American coastal regions, and 3.) seasonal prediction of storm activity in CanSIPS. Research Theme 1 evaluates six global reanalysis datasets to determine which best reproduces observed storm activity in the North American coastal regions, annually and seasonally, during the 1979-2010 time period using single-station surface pressure-based proxies; ERA-Interim is found to perform best overall. Research Theme 2, using ERA-Interim, investigates the potential predictability of extratropical storm activity (represented by mean sea level pressure [MSLP], absolute pressure tendency, and 10-m wind speed) during the 1979-2015 time period using analysis of variance. The detected potential predictability provides observation-based evidence showing that it may be possible to predict storm activity on the seasonal timescale. Additionally, using composite analysis, the El Niño-Southern Oscillation, Pacific Decadal Oscillation, and North Atlantic Oscillation are identified as possible sources of predictability in the North American coastal regions. Research Theme 2 provides a basis upon which seasonal forecasting of extratropical storm activity can be developed. Research Theme 3 investigates the seasonal prediction of North American coastal storm activity using the CanSIPS multi-model ensemble mean hindcasts (1981-2010). Quantitative deterministic, categorical deterministic, and categorical probabilistic forecasts are constructed using the three equiprobable category framework (below-, near-, and above-normal conditions) and the parametric Gaussian method for determining probabilities. These forecasts are then evaluated against ERA-Interim using the correlation skill score, percent correct score, and Brier skill score to determine forecast skill. Baseline forecast skill is found for the seasonal forecasts of all three storm activity proxies, with MSLP forecasts found to be most skilful and 10-m wind speed forecasts the least skilful. Skilful seasonal forecasting of North American coastal extratropical storm activity is, therefore, possible in CanSIPS. / Graduate
175

Sairaalahoito astmaatikon selviytymisen kuvaajana:rekisteritutkimus sairaalahoidossa olleiden astmaatikkojen ikä- ja sukupuolijakaumasta, uusien hoitojaksojen määrästä, hoitojaksojen vuodenaikavaihtelusta lapsilla, varusmiehillä ja aikuisilla sekä kuolleisuuden vuodenaikavaihtelusta

Harju, T. (Terttu) 25 March 1999 (has links)
Abstract This thesis discusses the age and sex distribution of previously hospitalised asthmatics and the number of new asthma-induced treatment periods as a proportion of all asthma-related hospital admissions. Seasonal fluctuations in treatment periods were analysed with respect to age, and seasonal fluctuations in mortality among previously hospitalised asthmatics by combining the hospital discharge register with the mortality statistics on the basis of the patients social security numbers. A total of 364,871 asthma-induced treatment periods were reported to the hospital discharge register in 1972-1992, of which 192,195 occurred in 1.1.1983-31.12.1992, and 28.6% of these were new cases. Treatment periods relative to population amounted to 2.76/1000 in 1972 and 3.43/1000 in 1992. The number of treatment periods among children was greatest at the age of 1 year, 11.2/1000 for boys and 5.5/1000 for girls, and lowest at 17 years among the boys, and 13 years among the girls. The numbers rose slowly in early adulthood (with the exception of men aged 18-22 years), reaching a new peak at 73 years of age for men, 10.3/1000, and 75 years for women, 9.5/1000, and decreasing gradually thereafter. A half of the treatment periods recorded for patients aged under 1 year or for men aged 20 years represented new cases, whereas otherwise the vast majority of the treatment periods were being readmissions. The seasonal peaks among the total of 59,624 hospital periods involving persons aged under 15 years reported to the discharge register in 1972-1992 occurred in May and October, and the lowest figures in January and July. Conscripts aged 18-22 years experienced 4894 asthma-induced treatment periods in 1982-1992, representing incidence rates of 8.5/1000 in 1982 and 27.7/1000 in 1992. The figure was highest in the month in which the conscripts entered service and the month following that. A total of 81,243 asthma-induced treatment periods were recorded for persons aged over 24 years in 1987-1992, the figures being highest in January-May, 18.2% above the monthly trend in January, and lowest in July, 26.1% below the monthly trend. 7622 of the asthmatics first admitted in 1977-1992 died at an age of over 24 years in 1987-1993, mortality being highest in December and January and lowest in August. Obstructive pulmonary diseases were the primary cause of death for 1283 persons, including 489 who died of asthma itself. Apart from children and men aged 18-22 years, asthma gives rise to a large number of treatment periods among the middle-aged and the elderly. Measures should be taken to diagnose it at an early stage in these groups and to intensify the treatment provided. In addition, the factors provoking asthma during military service should be minimised and preventive measures enhanced in the case of children in May and September. As far as adults are concerned, asthma-related hospitalisation may involve a greater fatality risk in winter, so that aggravations occurring in winter should be treated with particular care.
176

A critical evaluation of the causes of carcass condemnations in a South African cattle abattoir

Tlhapi, Petrus Thabo January 2013 (has links)
This study was conducted to investigate the causes and the effects of breed, gender and season on carcass condemnations post-mortem in a large South African abattoir. Condemnation of carcasses as a results of animal diseases and conditions has been identified as a problem in the South African beef industry, but the causes and extent of carcass condemnations have not been studied in detail. The importance of cattle management during transportation and pre-slaughter is generally appreciated, but a better understanding of the influence of breed, gender and season on the prevalence of carcass condemnations can help to improve slaughter management at large abattoirs. Diseases and conditions evaluated during this study were parafilaria, bruising, soiling, fever, peritonitis and pleuritis, abscesses, measles, oedema and intramuscular haemorrhage. Breeds of cattle slaughtered were Friesland, Bonsmara, Brahman, Angus, Afrikander, Hereford and Nguni cattle, grouped as males and females, and the seasonal effects investigated were confined to Autumn, Winter and Summer combined with Spring as it was not easy to distiquish between the two. Data was collected in a Grade A abattoir in South Africa in 2010. The experimental design involved 42 combinations based on their effects and interactions namely 7 breeds x 2 genders x 3 seasons. The model used in this procedure was based on the presence of conditions = (Intercept) x i x j x k where i~breed, j~gender and k~season. The binary response variable was the presence (value = 1) or absence (value = 2) of the respective condition. Overall, the significant order and extent of causes of bovine carcass condemnations evaluated in this particular abattoir during the period of study were peritonitis and pleuritis at 2.49%, soiling 2.33%, bruising 2.10%, parafilaria 0.54%, while other conditions had a negligible effect. Almost half of these carcass condemnations were due to soiling and bruising, which can be addressed by implementing better abattoir management and better management during transportation. Peritonitis and pleuritis were prevalent to a greater degree in Autumn, Soiling in Summer, bruising in winter and parafilaria more prevalent in Summer as well. Bonsmara bulls were more affected by peritonitis and pleuritis, soiling, bruising and parafilari compared to other breeds.. Overall breed, gender and season influenced carcass condemnations in large South African abattoir It is suggested that proper dehorning should be done at an early stage, especially in bulls of breeds like Bonsmara, Nguni, Friesland and Hereford, which predispose cattle to bruising which increases the number of carcass condemnations. Steps should be taken (i.e. proper handling techniques should be applied) to avoid injuries which may lead to internal bleeding, and eventually bruises (most probably due to fighting during transportation or in lairage), that can be avoided by using improved and upgraded facilities which include enough space per animal. In case of soiling, well-trained slaughter personnel, cattle handlers and cleaners should be hired to prevent bile and soil contamination during evisceration and to avoid mud or manure contamination durinmg lairage. It is recommended that employees be trained to help reduce the high rate of carcass condemnations. Breeds like Bonsmara and Brahman were more susceptible to peritonitis, pleuritis and parafilaria, so treatrment programmes are advisable for these breeds, especially those from regions where these conditions or diseases are more prevalent. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted
177

Distributions of glycine betaine and the methylamines in coastal waters : analytical developments and a seasonal study

Cree, Charlotte January 2015 (has links)
A novel technique comprising solid phase microextraction and gas chromatography has been developed to analyse the three methylamines (monomethylamine, dimethylamine and trimethylamine) at the concentrations expected in seawater. The volatility of the methylamines was exploited and allowed the headspace pre-concentration and gas chromatographic separation of the analytes. This method achieved limits of detection of 0.43 nmol dm-3, 2.50 nmol dm-3 and 0.37 nmol dm-3 for monomethylamine, dimethylamine and trimethylamine, respectively, which are lower than any previously reported for seawater. This technique was applied to natural samples collected from the Western English Channel (WEC) and the methylamines were successfully quantified. A liquid chromatography-mass spectrometry method was used to analyse glycine betaine in marine particulates. The volume filtered during sample collection was found to be critical in achieving accurate measurements of glycine betaine. Large filter volumes (1 L) significantly decreased observed concentrations compared to smaller volumes, and 10 mL was the optimised amount filtered. The difference in concentrations was attributed to large water volumes causing cell damage and loss of glycine betaine to the dissolved phase. Cell resilience was thought to play a role in the differences observed; for example, diatoms with their rigid silica cell walls were hypothesised to be more resilient to filtration stress. A seasonal study was carried out in the WEC using both 1 L and 10 mL samples and maximum glycine betaine concentrations were 50 nmol dm-3 and 484 nmol dm-3 in the 1 L and 10 mL samples, respectively. The latter concentrations were more than an order of magnitude higher than all previous measurements. Seasonality was observed and a significant correlation was found with chlorophyll a. Statistics were applied to the phytoplankton biomass data and contributions from specific phytoplankton taxa were identified, including from Prorocentrum minimum and Chaetoceros socialis.
178

Seasonal maize yield simulations for South Africa using a multi-model ensemble system

Le Roux, Noelien 30 November 2009 (has links)
Agricultural production is highly sensitive to climate and weather perturbations. Maize is the main crop cultivated in South Africa and production is predominantly rain-fed. South Africa’s climate, especially rainfall, is extremely variable which influences the water available for agriculture and makes rain-fed cropping very risky. In the aim to reduce the uncertainty in the climate of the forthcoming season, this study investigates whether seasonal climate forecasts can be used to predict maize yields for South Africa with a usable level of skill. Maize yield, under rain-fed conditions, is simulated for each of the magisterial districts in the primary maize producing region of South Africa for the period from 1979 to 1999. The ability of the CERES-Maize model to simulate South African maize yields is established by forcing the CERES-Maize model with observed weather data. The simulated maize yields obtained by forcing the CERES-Maize model with observed weather data set the target skill level for the simulation systems that incorporate Global Circulation Models (GCMs). Two GCMs produced the simulated fields for this study, they are the Conformal Cubic Atmospheric Model (CCAM) and the ECHAM4.5 model. CCAM ran a 5 and ECHAM4.5 a 6- member ensemble of simulations on horizontal grids of 2.1° x 2.1° and 2.8° x 2.8° respectively. Both models were forced with observed sea-surface temperatures for the period 1979 to 2003. The CERES-Maize model is forced with each ensemble member of the CCAM-simulated fields and with each ensemble member of the ECHAM4.5-simulated fields. The CERES-CCAM simulated maize yields and CERES-ECHAM4.5 simulated maize yields are combined to form a Multi-Model maize yield ensemble system. The simulated yields are verified against actual maize yields. The CERES-Maize model shows significant skill in simulating South Africa maize yields. CERES-Maize model simulations using the CCAM-simulated fields produced skill levels comparable to the target skill, while the CERES-ECHAM4.5 simulation system illustrated poor skill. The Multi-Model system presented here could therefore not outscore the skill of the best single-model simulation system (CERES-CCAM). Notwithstanding, the CERES-Maize model has the potential to be used in an operational environment to predict South African maize yields, provided that the GCM forecast fields used to force the model are adequately skilful. Such a yield prediction system does not currently exist in South Africa. / Dissertation (MSc)--University of Pretoria, 2009. / Geography, Geoinformatics and Meteorology / Unrestricted
179

Diet quality and season affect physiology and energetic priorities of captive Steller sea lions during and after periods of nutritional stress

Jeanniard Du Dot, Tiphaine 05 1900 (has links)
The ability of animals to contend with unpredictable seasonal shifts in quality and quantity of prey has implications for the conservation of wildlife. Steller sea lions(Eumetopias jubatus) were subjected to different quantities and qualities of food to determine what physiological and endocrine responses would occur and whether they differed between season (summer and winter) or diet (high-lipid Pacific herring Clupeapallasi vs. low-lipid Walleye Pollock Theragra chalcogramma). Eight females were divided among two groups. One (Group H) were fed herring for 28 days (baseline), then received a reduced caloric intake for a subsequent 28 days (restriction) to induce a 15%loss of body mass. The second (Group P) were also fed herring during the baseline followed by a reduced isocaloric diet of pollock during the restriction. Both groups subsequently returned to their baseline intake of herring for a 28-day controlled re-feeding. The two groups of sea lions lost identical mass during restrictions independent of species eaten, but did differ in the type of internal energy reserve (protein vs. lipids) they predominantly used. Group H lost significantly more lipids and less lean mass than Group P in both seasons. In summer, Group H also increased activity levels and decreased thermoregulation capacity to optimize energy allocation. No such changes were observed for Group P whose capacity to adjust to the reduced caloric intake seemed to have been blocked by the pollock diet. During winter, the sea lions spared energy allocated to activity (especially Group H) and preserved thermoregulation capacity. Changes in body mass was negatively related to free cortisol and positively related to IGF-1 in winter, but only IGF-1 was related to changes in mass in summer when lean mass regulation seemed more important. Levels of IGF-1 were associated with changes in protein metabolism in both seasons for both groups, but changes in body condition were never explained by the measured metabolites or hormones. The capacity to compensate for mass loss was seasonally dependent with sea lions displaying compensatory growth (by restoring lipid stores) in winter but not in summer. Summer appears to be a more difficult season for sea lions to recover from mild nutritional stress. These physiological findings can be used to refine bioenergetic models needed for the conservation of Steller sea lion populations. / Science, Faculty of / Zoology, Department of / Graduate
180

Phytoplankton Communities in Temperate Rivers

Contant, Jacinthe January 2012 (has links)
The structure of phytoplankton communities was examined seasonally across five rivers with a focus on small cells and their relative importance. Picophytoplankton (0.2-2 μm), previously considered insignificant in rivers, reached densities as high as those observed in lakes and oceans (~ 10e4-10e5 cells/mL). Their relative importance was not a function of trophic state with the highest contribution to algal biomass found in the most eutrophic river. Body size distributions were analyzed from both chlorophyll-a size fractions and taxonomic enumerations; no significant effect of river or season was detected, suggesting that phytoplankton size distribution is not a useful metric of change in rivers. Unlike lake ecosystems, the rivers were uniformly dominated by small cells (< 20 μm). Taxonomic analyses of the seasonal succession did not reveal a common periodicity of particular divisions (e.g. diatoms). However, strong dominance was more typical of eutrophic rivers even though taxa richness was similar.

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