The effects of temperature and busulfan (Myleran) on the yellowtail tetra Astyanax altiparanae (Pisces, Characiformes) spermatogenesis

We aimed to standardize a protocol to suppress spermatogenesis in the characiform fish, Astyanax altiparanae, for future use as a host in germ cell transplant research, opening opportunities for a range of studies, such as spermatogenesis analyses and transgenesis because this species presents livestock characteristics to be used as a biological model. The effects of the chemotherapeutic busulfan (formulated as Myleran), which is used as medicine, therefore not as toxic to humans manipulation as analytical grade busulfan (Fluka) used in previous studies, were evaluated at physiological temperature of 28 °C, ideal for growth and reproduction of A altiparanae, and also at increased temperature 35 °C. The temperature groups were divided into three treatment groups: busulfan, DMSO only, and an untreated control. Macroscopic, histologic, stereological, and ultrastructure analysis showed that, at 28 °C, busulfan did not cause depletion of germ cells in A altiparanae. However, at 35 °C, sterilization was observed 3 weeks after the initial application. Similar results were obtained with maintenance of fish at 35 °C for a longer period with no accompanying Myleran treatment. This procedure allows reduction in stress and lower mortality resulting from manipulation during busulfan injection and is also suitable for mass treatment because large numbers of fish can be incubated in warm water.

Adult acclimation to combined temperature and pH stressors significantly enhances reproductive outcomes compared to short-term exposures

This study examined the effects of long-term culture under altered conditions on the Antarctic sea urchin, Sterechinus neumayeri. Sterechinus neumayeri was cultured under the combined environmental stressors of lowered pH (-0.3 and -0.5 pH units) and increased temperature (+2 °C) for 2 years. This time-scale covered two full reproductive cycles in this species and analyses included studies on both adult metabolism and larval development. Adults took at least 6-8 months to acclimate to the altered conditions, but beyond this, there was no detectable effect of temperature or pH. Animals were spawned after 6 and 17 months exposure to altered conditions, with markedly different outcomes. At 6 months, the percentage hatching and larval survival rates were greatest in the animals kept at 0 °C under current pH conditions, whilst those under lowered pH and +2 °C performed significantly less well. After 17 months, performance was not significantly different across treatments, including controls. However, under the altered conditions urchins produced larger eggs compared with control animals. These data show that under long-term culture adult S. neumayeri appear to acclimate their metabolic and reproductive physiology to the combined stressors of altered pH and increased temperature, with relatively little measureable effect. They also emphasize the importance of long-term studies in evaluating effects of altered pH, particularly in slow developing marine species with long gonad maturation times, as the effects of altered conditions cannot be accurately evaluated unless gonads have fully matured under the new conditions.

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by 20-50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37% compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

Ocean acidification mediates photosynthetic response to UV radiation and temperature increase in the diatom Phaeodactylum tricornutum

Increasing atmospheric CO2 concentration is responsible for progressive ocean acidification, ocean warming as well as decreased thickness of upper mixing layer (UML), thus exposing phytoplankton cells not only to lower pH and higher temperatures but also to higher levels of solar UV radiation. In order to evaluate the combined effects of ocean acidification, UV radiation and temperature, we used the diatom Phaeodactylum tricornutum as a model organism and examined its physiological performance after grown under two CO2 concentrations (390 and 1000 µatm) for more than 20 generations. Compared to the ambient CO2 level (390 µatm), growth at the elevated CO2 concentration increased non-photochemical quenching (NPQ) of cells and partially counteracted the harm to PS II (photosystem II) caused by UV-A and UV-B. Such an effect was less pronounced under increased temperature levels. The ratio of repair to UV-B induced damage decreased with increased NPQ, reflecting induction of NPQ when repair dropped behind the damage, and it was higher under the ocean acidification condition, showing that the increased pCO2 and lowered pH counteracted UV-B induced harm. As for photosynthetic carbon fixation rate which increased with increasing temperature from 15 to 25 °C, the elevated CO2 and temperature levels synergistically interacted to reduce the inhibition caused by UV-B and thus increase the carbon fixation.

Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO2

Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from ~0.5-250 µmol/kg (i.e. ~20-6000 µatm pCO2) at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean.

Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings

The Bragg wavelength of a PMMA based fiber grating is determined by the effective core index and the grating pitch, which, in temperature sensing, depend on the thermo-optic and thermal expansion coefficients of PMMA. These two coefficients are a function of surrounding temperature and humidity. Amorphous polymers including PMMA exhibit a certain degree of anisotropic thermal expansion. The anisotropic nature of expansion mainly depends on the polymer processing history. The expansion coefficient is believed to be lower in the direction of the molecular orientation than in the direction perpendicular to the draw direction. Such anisotropic behavior of polymers can be expected in drawn PMMA based optical fiber, and will lead to a reduced thermal expansion coefficient and larger temperature sensitivity than would be the case were the fiber to be isotropic. Extensive work has been carried out to identify these factors. The temperature responses of gratings have been measured at different relative humidity. Gratings fabricated on annealed and non-annealed PMMA optical fibers are used to compare the sensitivity performance as annealing is considered to be able to mitigate the anisotropic effect in PMMA optical fiber. Furthermore an experiment has been designed to eliminate the thermal expansion contribution to the grating wavelength change, leading to increased temperature sensitivity and improved response linearity. © 2014 Copyright SPIE.

Climate change and biotic invasions: a case history of a tropical woody vine

The impacts of climate change in the potential distribution and relative abundance of a C3 shrubby vine, Cryptostegia grandiflora, were investigated using the CLIMEX modelling package. Based upon its current naturalised distribution, C. grandiflora appears to occupy only a small fraction of its potential distribution in Australia under current climatic conditions; mostly in apparently sub-optimal habitat. The potential distribution of C. grandiflora is sensitive towards changes in climate and atmospheric chemistry in the expected range of this century, particularly those that result in increased temperature and water use efficiency. Climate change is likely to increase the potential distribution and abundance of the plant, further increasing the area at risk of invasion, and threatening the viability of current control strategies markedly. By identifying areas at risk of invasion, and vulnerabilities of control strategies, this analysis demonstrates the utility of climate models for providing information suitable to help formulate large-scale, long-term strategic plans for controlling biotic invasions. The effects of climate change upon the potential distribution of C. grandiflora are sufficiently great that strategic control plans for biotic invasions should routinely include their consideration. Whilst the effect of climate change upon the efficacy of introduced biological control agents remain unknown, their possible effect in the potential distribution of C. grandiflora will likely depend not only upon their effects on the population dynamics of C. grandiflora, but also on the gradient of climatic suitability adjacent to each segment of the range boundary.

Fluência de materiais

A presente dissertação apresenta uma abordagem ao tema Fluência, com um desenvolvimento geral para quatro materiais: madeira, alumínio, betão e aço. No entanto, particularizou-se este estudo apenas para dois destes materiais, a madeira e o alumínio. A madeira é um material viscoelástico, logo fortemente influenciado quando submetido a uma ação constante (Fluência) sendo agravada com alterações do teor em água. Iniciou-se o estudo, com uma introdução aos objetivos principais e a revisão teórica do conhecimento da propriedade mecânica (Fluência). Efetuou-se o estudo inicial para os quatro materiais indicados. Posteriormente, fez-se avaliação do efeito mecânico sortivo durante 60 dias com sete ciclos, em provetes de dimensões 20 x 20 x 400 mm3 (escala 1:10) de madeira de Eucalyptus globulus Labill. Recorrendo ao levantamento de um conjunto de modelos numéricos, procedeu-se ao ajuste e extrapolação do comportamento, em Fluência, para distintos períodos de tempo (1, 10 e 50 anos). Os resultados obtidos demonstraram que a madeira de Eucalipto não apresenta um limite no seu comportamento em Fluência, logo instável para os 60 dias de duração de ensaio. Os diferentes modelos de Fluência (x6) apresentaram uma variabilidade crescente de resultados, de acordo com o aumento de extrapolação dos resultados. Para a espécie de madeira de Eucalipto constatou-se ainda, que o ajuste e extrapolação de deformação para 50 anos ultrapassaram os valores sugeridos pelo Eurocódigo 5. A última parte deste trabalho, incidiu sobre o desenvolvimento da metodologia do ensaio em flexão de 3 provetes de alumínio similares, cujas dimensões eram de 20 x 20 x 400mm3. O objetivo desta metodologia foi avaliar o seu comportamento em Fluência. Numa primeira fase, foi aplicada uma carga contante de 160 kN. E numa segunda fase, foi aplicada o dobro dessa carga sujeita adicionalmente a uma temperatura bastante superior à temperatura ambiente (a rondar os 50 oC). Conclusivamente verificou-se que o alumínio não apresenta deformação por Fluência, para as condições de ensaio apresentadas.

Physiological stress responses in the warm-water fish matrinxã (Brycon amazonicus ) subjected to a sudden cold shock

The present work evaluated several aspects of the generalized stress response [endocrine (cortisol), metabolic (glucose), hematologic (hematocrit and hemoglobin) and cellular (HSP70)] in the Amazonian warm-water fish matrinxã (Brycon amazonicus ) subjected to an acute cold shock. This species farming has been done in South America, and growth and feed conversion rates have been interesting. However, in subtropical areas of Brazil, where the water temperature can rapidly change, high rates of matrinxã mortality have been associated with abrupt decrease in the water temperature. Thus, we subjected matrinxã to a sudden cold shock by transferring the fish directly to tanks in which the water temperature was 10ºC below the initial conditions (cold shock from 28ºC to 18ºC). After 1h the fish were returned to the original tanks (28ºC). The handling associated with tank transfer was also imposed on control groups (not exposed to cold shock). While exposure to cold shock did not alter the measured physiological conditions within 1h, fish returned to the ambient condition (water at 28º C) significantly increased plasma cortisol and glucose levels. Exposure to cold shock and return to the warm water did not affect HSP70 levels. The increased plasma cortisol and glucose levels after returning the fish to warm water suggest that matrinxã requires cortisol and glucose for adaptation to increased temperature.

RNA-seq analysis of the Quercus suber root response to drought

Dissertação de mestrado em Plant Molecular Biology, Biotechnology and Bioentrepreneurship

Warm Front, Better Health: Health Impact Evaluation of the Warm Front Scheme

About 4 million households in the UK cannot adequately heat their homes in winter due to low income and poor quality housing, the two main causes of fuel poverty. The primary impact of fuel poverty is cold homes in winter which can lead to various health problems and even death among the vulnerable young and the elderly population. The government launched the Warm Front scheme in 2000 to tackle fuel poverty among the vulnerable households in England by providing energy efficiency measures in the forms insulation and modern heating system(??). By 2004, about 770,000 households had benefited from the Warm Front scheme and a total of 2 million households are still expected to benefit by 2010. Since 2001, the Bartlett has been investigating with London School of Hygiene & Tropical Medicine and Sheffield Hallam University, the health and the environmental impact of the Warm Front scheme. This investigative study is the most detailed to date on fuel poor dwellings based on detailed surveys of household and dwelling data, fuel consumption record and monitored temperature and relative humidity from 3,100 dwellings before and after the energy efficiency measures. The Warm Front investigation was expected to continue until the end of 2007. The findings from the investigation indicated that the Warm Front scheme was likely to have benefits in terms of improved thermal comfort and well-being as a result of mean temperature rise of 1.6C in the living room and 2.8C in the bedroom. Warm Front also lead to a decrease in indoor relative humidity mainly from the increased temperature since there appeared to be little impact on vapour pressure from changes in air tightness. Pressure test results indicated that the effects of air tightness measures such as draught stripping and cavity wall insulation were offset by the installation of a central heating system, particularly when the pipe work feeding radiators was installed below timber floors.

Interaccions arbre-arbust al límit superior del bosc i efectes de gradients bioclimàtics en la vegetació

Durant el periode d’elaboració d’aquesta tesi hem aprofundit en el coneixement dels factors que controlen les dinàmiques espacio-temporals del límit superior del bosc. Aquest ecotò se situa entre el límit superior del bosc i els prats alpins i és susceptible a canvis ambientals, fet que provoca que fluctuï altitudinalment i latitudinalment en funció d’aquests canvis. Els motius d’aquesta dinàmica s’ha estudiat sovint des d’un punt de vista climàtic, però mai fins ara s’havia estudiat des d’un punt de vista de les interaccions entre organismes. Per aquest fet hem estat evaluant l’efecte de les interaccions planta-planta en la regulació de la dinàmica supraforestal. L’estudi l’hem emmarcat en un context alpí (als Pirineus Catalans) i en un context subàrtic (Lapònia, Suècia), fet que ens ha permès fer un estudi comparatiu en dos ecotons contrastats però homòlegs ecològicament. Hem desenvolupat una sèrie d’experiments considerant diversos factors (augment de temperatura, quantitat de nutrients, presència d’arbust, posició en l’ecotò); en les dues zones d’estudi hem fet una plantació de plançons dels arbres formadors del límit del bosc en les diverses situacions derivades de la combinació d’aquests factors, i hem fet el seguiment fenològic dels plançons durant tres periodes de creixement. Els resultats dels experiments ens han permès veure que les interaccions entre organismes tenen una gran importància en la regulació de la dinàmica supraforestal, tant als Pirineus com a Lapònia. Les interaccions planta-planta i planta-herbívors determinen el reclutament de plançons i per tant l’estructuració de les comunitats supraforestals. Per altra banda, la posició en l’ecotò evidencia la presència d’un gradient bioclimàtic; les manipulacions ambientals de temperatura i nutrients originen una resposta generalment positiva en el desenvolupament dels plançons, indicant que canvis en aquestes variables pot suposar alteracions notables de l’estructura forestal del límit del bosc. Per altra banda en aquest projecte també hem aprofundit en temes relacionats amb l'efecte dels gradients altitudinals en la distribució de plantes vasculars als Pirineus Catalans.

Interaccions arbre-arbust al límit superior del bosc i efectes de gradients bioclimàtics en la vegetació

Durant el periode d’elaboració d’aquesta tesi hem aprofundit en el coneixement dels factors que controlen les dinàmiques espacio-temporals del límit superior del bosc. Aquest ecotò se situa entre el límit superior del bosc i els prats alpins i és susceptible a canvis ambientals, fet que provoca que fluctuï altitudinalment i latitudinalment en funció d’aquests canvis. Els motius d’aquesta dinàmica s’ha estudiat sovint des d’un punt de vista climàtic, però mai fins ara s’havia estudiat des d’un punt de vista de les interaccions entre organismes. Per aquest fet hem estat evaluant l’efecte de les interaccions planta-planta en la regulació de la dinàmica supraforestal. L’estudi l’hem emmarcat en un context alpí (als Pirineus Catalans) i en un context subàrtic (Lapònia, Suècia), fet que ens ha permès fer un estudi comparatiu en dos ecotons contrastats però homòlegs ecològicament. Hem desenvolupat una sèrie d’experiments considerant diversos factors (augment de temperatura, quantitat de nutrients, presència d’arbust, posició en l’ecotò); en les dues zones d’estudi hem fet una plantació de plançons dels arbres formadors del límit del bosc en les diverses situacions derivades de la combinació d’aquests factors, i hem fet el seguiment fenològic dels plançons durant tres periodes de creixement. Els resultats dels experiments ens han permès veure que les interaccions entre organismes tenen una gran importància en la regulació de la dinàmica supraforestal, tant als Pirineus com a Lapònia. Les interaccions planta-planta i planta-herbívors determinen el reclutament de plançons i per tant l’estructuració de les comunitats supraforestals. Per altra banda, la posició en l’ecotò evidencia la presència d’un gradient bioclimàtic; les manipulacions ambientals de temperatura i nutrients originen una resposta generalment positiva en el desenvolupament dels plançons, indicant que canvis en aquestes variables pot suposar alteracions notables de l’estructura forestal del límit del bosc. Per altra banda en aquest projecte també hem aprofundit en temes relacionats amb l'efecte dels gradients altitudinals en la distribució de plantes vasculars als Pirineus Catalans.

Microfabrics in carbonate mylonites along a large-scale shear zone (Helvetic Alps)

Carbonate mylonites with varying proportions of second-phase minerals were collected at positions of increasing metamorphic grade along the basal thrust of the Morcles nappe (Helvetic nappes, Switzerland). Variations of temperature, stress, and strain rate, changes in chemistry of solid and fluid phases, and differing degrees of strain localization and annealing were tracked by measuring the shapes, mean sizes, and size distributions of both matrix and second-phase grains, as well as crystal preferred orientation (CPO) of the matrix. Field structures suggest that strain rate was constant along the fault. The mean and distribution of the calcite grain sizes were affected most profoundly by temperature: Increased temperature, presumably accompanied by decreased stress, correlated with larger mean sizes and wider size distributions. At a given location, the matrix grains in mylonites with more second-phase particles are, on average, smaller, have narrower size distributions, and have more elongate shapes. For example, mylonites with 50 vol.% of second phases have matrix grain sizes half that of pure mylonites. Changes in calcite chemistry and the presence of synkinematic fluids seemed to influence microfabric only weakly. Temporal variations in conditions, such as exhumation-induced cooling, apparently provoke changes in temperature, stress, and strain rate along the nappe. These changes result in further strain localization during retrograde conditions and cause the grain size to be reduced by an additional 50%. The matrix CPO strengthens with increasing temperature or strain, but weakens and rotates with increasing second-phase content, These fabric changes suggest differing rates of grain growth, grain size reduction, and development of CPO owing to variations in the deformation conditions and, perhaps, mechanisms. To interpret natural mylonite structures or to extrapolate mechanical data to natural situations requires careful characterization of the microfabric, and, in particular, second-phase minerals. (c) 2007 Elsevier B.V, All rights reserved.

USO DA RMN DE BAIXA RESOLUÇÃO NA AVALIAÇÃO DA DINÂMICA MOLECULAR DO Origanum vulgare

In this work, proton NMR relaxometry was used to measure the behavior of spin-lattice relaxation time with T1H as the time constant, and also of spin-spin relaxation time with the time constant T2H. These relaxometry parameters were determined to better understand the changes in the main structures present in commercial and in nature forms of origanum. The T1H relaxation data showed that the structures which had higher molecular mass were more sensitive to degradation with increased temperature treatment. According to the values of the T2H parameter, up to 150 degrees no significant change in the mobility and organization of water was observed. These data infer that the ideal cooking temperature and tea preparation mode for this herb should be around 100 degrees for the sample not to lose its characteristics. Also, it is not advisable to cook this herb at higher than 150 degrees but better to consume it at room temperature, especially give commercial herb has already been dehydrated.