Long-lived, top-level predators, such as some marine mammals, serve as important indicators of ecosystem health. Assessing the abundance and habitat use of such marine top predators is essential for the formulation of effective conservation and management actions. There is considerable concern over the viability of small humpback dolphin opulations across a global scale and a number of studies have raised concerns over their vulnerability to extinction. In light of the recent uplisting of Indian Ocean humpback dolphins (Sousa plumbea) to ‘Endangered’ on the South African Red Data list, there is an urgent need for a greater understanding of the abundance and spatial distribution of this species along the South African coastline. Using small vessels as survey platforms between March 2014 and June 2015, this study attempted to determine the abundance, spatial distribution and habitat preferences of Indian Ocean humpback dolphins along 150 km of South Africa’s south coast. A further aim was to assess the utilisation of the current Marine Protected Area network by humpback dolphins along this coastline relative to areas outside of formal protection. Mark-recapture methods applied to photo-identification data produced abundance estimates of 84 individuals (95% CI: 72-115) within the study area for both open and closed models. An average group size of 3.94 individuals (range 1-12; SD = ± 2.82) was observed during the study, indicating a decrease in average group size of ~45 % from a previous assessment in 2002/03. Such a decline in group size could potentially be a result of a change in social structure in response to reduced prey availability. Spatial analyses of humpback dolphin geographic positions, using a kernel density estimator (KDE) and effort-weighted density grid analyses, indicate that the species is unevenly distributed over the coastal zone within the area. Sightings occurred at the highest densities within Buffels Bay and along Goukamma MPA, followed by Plettenberg Bay, Nature’s Valley, and around the Bloukrans, Elandsbos and Groot River East mouths. Habitat preference was assessed using a standard classification-based method and the results indicate a strong preference, in particular, for Dissipative Intermediate Sandy Coast habitat, followed by Very Exposed Rocky Coast, Intermediate Sandy Coast, Estuarine Shore, Mixed Shore and Inshore Reef habitats. Areas of high humpback dolphin densities appear to be associated with these habitat types, especially with Dissipative-Intermediate Sandy Coast habitat. Humpback dolphins were sighted at relatively low densities along stretches of coastline consisting predominately of Exposed Rocky Shore habitat. Long expanses of this habitat type may limit humpback dolphin movements along the coast. The observed patterns in distribution and habitat preferences may be linked to the availability of prey and/or the avoidance of predators. Average sightings per kilometer travelled (SPUE) indicate that the utilisation of the Robberg and Tsitsikamma MPAs by humpback dolphins was low, most likely due to the low availability of sandy coastline in these areas. In contrast, the utilisation of the Goukamma MPA, which is characterised by a high availability of Dissipative-Intermediate Sandy Coast, was very high. The low population numbers and declines in average group size of Indian Ocean humpback dolphins within the study area warrant concern and call for effective conservation and management measures. In light of ever-increasing levels of anthropogenic threats to coastal areas, future research and long-term monitoring of the population is essential to broaden our knowledge of the species and to detect population trends.

Disorders affecting articular cartilage are amongst the most common problems in orthopaedics. Osteoarthritis, the end stage of the disease of articular cartilage, reduces the quality of life for tens of millions of people in the world, and has a profound impact on the economics of industrialized countries. Despite progress in articular cartilage research, the problem is still far from being defeated. Various models e.g. in vitro cartilage explants and in vivo animal models, have been established for cartilage research, but each has its own limitations. Thus, a novel ex vivo isolated joint organ culture model was developed. Bovine metatarsophalangeal joints were chosen as a suitable synovial joint because it consists of a hinge-type joint that is similar to the human knee joint, and has a large cartilage surface that provides enough space for multiple sampling in the same joint. The joints were isolated aseptically and placed into culture media. The viability of chondrocytes, glycosaminoglycan (GAG) content of cartilage matrix, cartilage morphology and water content of matrix were evaluated under different culture conditions, i.e. static, static with flowing media, and dynamic with different durations of the movement period. The model was used to investigate the effect on the sharp scalpel cartilage injury of adding serum to the culture medium by culturing the whole joint explants in serum-supplied or serum-free media. The feasibility of investigating the early phases of chondrocyte implantation in this model was also studied: circular holes of 2.5 mm diameter were created by making a pilot hole with a 2.0 mm drill followed by using a fresh 2.5 mm biopsy punch. Allogeneic isolated chondrocytes at different passages were aggregated as cell pellets and implanted in the holes to evaluate their integration ability and the response from the recipient cartilage. Results from the static model showed that, after 28 days culture, the chondrocytes were still alive with 66.5%, 80.9% and 46.9% viability in the superficial, middle and deep zones, respectively. The GAG content of the static model decreased 19.2% after the first week of culture and then lost another 15.0% during the third week. Paradoxically, at end of the 4th week the GAG level rebounded to some extent and increased 19.0% relative to the previous week. Interestingly, the cell viability of all three zones improved if the culture fluid was flowing as seen with the experiments carried out with stirred media or dynamic movement of the articular surfaces. (e.g. for the stirred media after 28 days of culture the chondrocyte viability was 80.6%, 92.4% and 70.4% for the superficial, middle and deep zones respectively.) The GAG content was maintained at a constant level in the contact area of the dynamic model, but decreased as in the media-stirred model and non-contact area of the dynamic model to a similar extent to that observed with the static model. In the injury model, the GAG content fell approximately 10.8% straight after the scalpel cut, but no further loss was observed if the joint was cultured in the serum-supplied media. In contrast, if the injured joint was cultured in the serum-free media, the GAG content continued to fall week by week and finally dropped by 41.7% at the end of the 4th week. In the chondrocyte implantation model, the majority of the host chondrocytes around the circular defect were alive (78.5 % viability). Viewed from the surface, the dead cells were all within 20 μm from the cut edge. The implanted chondrocytes, which were aggregated as cell pellets, began to transform their shapes and spread to the surrounding surface of the recipient cartilage, but did not appear to integrate with the host tissue during the first 2 weeks of culture. The results supported the validity of this ex vivo joint model and demonstrated that the chondrocytes subjected to flow of the media or dynamic loads survived well over a 4 week period. Of importance was the finding that there was no measured loss of the matrix GAG content when the joints were under dynamic load compared to all of the non-loaded conditions. This whole joint model could be of value in providing a more natural and controllable platform where research involving the normal processes or pathologic mechanisms of articular cartilage can be investigated, as well as the early response to newly developed pharmacological agents and cartilage tissue engineering constructs.

[pt] A dessalinização térmica é uma técnica utilizada em diversas partes do mundo para produção de água. Países como Estados Unidos, Israel, Espanha e Grécia utilizam esse tipo de sistema em grande escala, garantindo um abastecimento constante para alguns pontos de seu território e contribuindo para o aperfeiçoamento dos sistemas de produção. No Brasil, apesar da vasta bacia hidrográfica e da existência de grandes reservatórios subterrâneos, a dessalinização térmica poderia ser vista como alternativa de produção para apoiar o desenvolvimento agrícola e industrial em algumas regiões, criando também melhores condições sociais para a população beneficiada, especialmente no nordeste brasileiro. Nessa dissertação propomos um método para avaliação preliminar de diversos cenários para implantação de tais sistemas. A avaliação aborda inicialmente a definição do dessalinizador, realizada através das formulações disponíveis em trabalhos acadêmicos que têm como base a Primeira Lei da Termodinâmca. Tais formulações foram adaptadas para o caso em estudo. Em seguida são avaliados os principais parâmetros para viabilidade do projeto, tais como Valor Presente Líquido (VPL) e Índice de Lucratividade (IL), de forma a demonstrar se o projeto seria ou não viável. Para consolidação da metodologia utilizada foi criado um programa que permite a avaliação de diversos cenários de maneira independente, sendo de fácil acesso e de grande flexibilidade para o usuário interessado neste tema. / [en] Thermal desalination is a technology used in many places for water production. Some countries use desalination to produce big volume of water, like USA, Israel, Spain and Greece, aiming for the steady supply of water to some specific regions, contributing to the improvement of production systems. In Brazil, inspite of the huge volume of water available through the rivers, thermal desalination should be considered as an alternative for water production supporting the development of country for food production and for industry, specially in the northeastern region. In this work, a method of evaluation for different water supply needs was conceived, in order to perform the preliminary evaluation of this kind of system. It begins with the definition of the thermal desalinator which will compose the production system. This first step was based on First Law of Thermodynamics formulations available in technical articles used as reference. After technical analysis, the main parameters used for the study of feasibility are defined, for example, the Net Present Value. The methodology extracted from reference articles was simplified and converted into an algorithm, developted for an easy evaluation of different situations.

>Magister Scientiae - MSc / The blood-brain barrier (BBB) is an interface between the brain parenchyma and the circulating system. This barrier plays a vital role in protecting the CNS by restricting free paracellular diffusion of molecules from the systemic circulation. Methamphetamine (MA) is a highly addictive psychostimulant and has demonstrated neurotoxic properties as well as the ability to compromise the BBB. MA exposure is strongly linked with increased oxidative stress which can result in a decrease in the integrity of the BBB.The aim of this study was to investigate in vitro effects of pure and street MA "tik" on DNA proliferation and cell cycles in mouse brain endothelial (bEnd5) cells. Trypan blue was used to determine effects of MA (0.0001M-1mM) on cell viability and % cell growth. The Cell Titer Glo® luminescent assay and nonradioactive analogue, 5-bromo-2'-deoxyuridine (BrdU) was used to detect ATP and DNA levels, respectively. Cell cycles (propidium iodide incorporation) were analysed using flow cytometry. Statistical analysis was performed using Wilcoxin Rank Sum Test in which P<0.05 was denoted as significant. Results of this study showed that: 1. Viability of bEnd5 cells exposed to all selected concentrations of MA were unaffected when compared to controls (P>0.05). 2. % Cell growth was suppressed by MA exposure at 96hrs in comparison to that of controls (P≤0.03). 3. Cells exposed to MA had significant higher ATP concentrations than control cells at 96hrs (P ≤.0.03) 4. DNA synthesis was markedly suppressed in cells exposed to pure MA and street MA sample 4 (P≤0.03), while was similar and higher in cells exposed to street MA sample 1 (P=0.39), and street MA sample 2 and 3 (P≤0.04), respectively at 96hrs. 5. bEnd5 cell were arrested between 72 and 96hrs at the G1-S phase. In conclusion, this study demonstrated pure and illicit samples of MA obtained from forensic police did not affect the viability of bEnd5 cells, however resulted in the significant suppression of their cell numbers. This growth inhibition may be due to MA-induced cell cycle arrest at the G1-S phase. The study also showed that compounds found in the samples of street MA produced results significantly different to that of pure MA.

Please read the abstract in the section 00front of this document / Dissertation (MSc (Genetics))--University of Pretoria, 2007. / Genetics / unrestricted

Nitrification is currently the most common means of ammonia removal from wastewaters in temperate climates. In conventional suspended growth systems operating in northern climate regions, nitrification completely ceases at temperatures below 8°C. This is a considerable concern in passive treatment systems where wastewater temperatures can reach as low as 1°C for extended periods in the winter months. There is evidence biofilm technologies have the ability to nitrify at low temperatures, however, the literature is missing an understanding of low temperature nitrification and the subsequent impacts during seasonal changes. Additionally, there is an urgent need to gain a fundamental knowledge of the interplay between nitrifying performance optimization, biofilm morphology and the microbiome. This research aims to fill these needs using nitrifying moving bed biofilm reactors (MBBRs) at the lab and pilot scale. This research concluded the most important factor determining MBBR carrier selection is a combination of surface area and pore space size. Although high surface area to volume carriers are attractive, the propensity to clog at high loading rates significantly decreases the removal rates. The viability of the biomass and ammonia oxidizing bacterial communities were not significantly changed, indicating the ammonia removal rates were reduced due to loss of surface area in the clogged carriers. Operation at 1°C demonstrated significant rates of nitrification can be attained and stable for extended periods of operation. This study developed the first kinetic curve at 1°C with a maximum removal rate of 0.35 gN/m2·d. The performance of the post carbon removal nitrifying MBBR systems were shown to be enhanced at 1°C by an increase in the viable embedded biomass as well as thicker biofilm. This effectively increased the number of viable cells present during low temperature operation, which partially compensated for the significant decrease in rate of ammonia removal per nitrifying cell. At all studied loading rates at 1°C, the ammonia oxidizing bacteria were primarily in the family Nitrosomonadaceae (greater than 95 percent abundance of AOB population) and the nitrite oxidizing bacteria were primarily the genus Nitrospira (greater than 99 percent abundance of NOB population). Operation at 20°C demonstrated high rates of removal in high loaded condition and robustness in extreme low loaded conditions. In both high loaded and extreme low loaded conditions the viability of the nitrifying biomass was sustained, with the family Nitrosomonadaceae as the primary ammonia oxidizing bacteria and the genus Nitrospira as the primary nitrite oxidizing bacteria. In extreme low loaded conditions and as well during start-up phases there are high prevalence of bacteria not directly related to the nitrification process. Their presence however indicates a dynamic process with changes in microbial composition within the biofilm matrix in response to varying conditions. Change in microbial composition likely helps stabilize and maintain the biofilm matrix enhancing process robustness in the temperate climates. The new knowledge gained in this research optimizes the operation of nitrifying MBBR systems and elucidates the impacts of operational conditions on the biofilm and microbial community of nitrifying MBBR systems to further our understanding of nitrifying attached growth treatment technologies. The results of this study are anticipated to be used to design the first MBBR treatment system for year round ammonia removal in passive treatment systems located in northern climate regions.

As leveduras são de relevante importância dentro da agroindústria sucroalcooleira devido sua participação no processo fermentativo de produção de álcool. Deste modo, faz-se necessário o conhecimento deste agente fermentativo com destaque para Saccharomyces cerevisiae, principal gênero. O objetivo deste trabalho foi estudar a linhagem de levedura S. cerevisiae Y904, exposta a condições não proliferantes, após fermentação em meio que sofreu adição de óleo vegetal e sua possível correlação com manutenção da viabilidade celular. Foram realizadas análises para contagem de unidades formadoras de colônias, viabilidade celular, concentração celular, nitrogênio total na levedura e no meio, carboidratos totais, trealose e glicogênio. As leveduras submetidas a condições não proliferantes apresentaram menores teores de carboidratos totais, com destaque para trealose e glicogênio, em relação às leveduras comerciais. Saccharomyces cerevisiae sofreu queda de viabilidade acentuada após 24 h em solução fisiológica, em condições não proliferantes, sob agitação de 90 rpm e temperatura de 30 ± 1°C, seguida de uma acentuada autólise a partir de 120 h (5°dia), provavelmente, devido ao teor de carboidratos de reserva da célula que se encontravam em valores extremamente baixos, da ordem de 0,15 mg de trealose em 100 mg da matéria seca e 4 mg de glicogênio em 100 mg da matéria seca. A partir desse ponto entraram em total desorganização celular. / Yeast is highly important in sugar and alcohol agroindustry due to its role in the fermentative process of alcohol production. Thus, it is necessary to know this microorganism, most specially the Saccharomyces cerevisiae, the main species. The objective of this work was to study the strain Y904 of the yeast Saccharomyces cerevisiae under non-proliferating conditions after fermentation in a medium in which it was added vegetable oil and verify its possible correlation with the maintenance of the cellular viability. Analyses were performed in order to determine colony forming units, cellular viability, cellular concentration, total nitrogen in yeast and in medium, total carbohydrates and trehalose and glycogen contents. The yeast submitted to non-proliferating conditions presented a lower content of total carbohydrates, specially trehalose and glycogen, when compared to commercial yeasts. The viability of the yeast Saccharomyces cerevisiae Y904 markedly decreased after 24 hours in physiological solution under non-proliferating conditions in a shaker for 90 rpm at 30 ± 1°C. It was observed an accentuated autolysis from the 120 th hour (5 th day) on. This was probably because of the very low content of the carbohydrates of reserve in the cells, 0.15 mg of trehalose and 4.0 mg of glycogen in 100 mg of dry weight. From this point the cells began a total cellular disorganization.

Philosophiae Doctor - PhD / Typha capensis (T. capensis), commonly known as bulrush, is a medicinal plant found growing in the wetland areas of South Africa. In traditional medicine, rhizome decoctions of T. capensis are used to treat a wide variety of ailments, including venereal disease, dysentery, diarrhoea and low libido in men. Previously, T. capensis rhizomes were shown to be a rich source of antioxidants, such as catechin and epicatechin, inhibiting both reactive oxygen species and reactive nitrogen species. The antioxidant capacity of such plant species serves as a reservoir of electrons to transport them into gold salt for the production of gold nanoparticles through green nanotechnology. Therefore, this study aimed to investigate the application of T. capensis in green nanotechnology and nano-medicine.

The master´s thesis deals with research of viability and contraction measurement of cardiomyocytes. The work is divided into two main areas – theoretical and practical part. Theoretical part is aimed at electrophysiology of cardiomyocytes. Practical part includes detection of contractibility based on eccentricity in program Matlab. For research of viability, were used several media for example DMEM and MPRI.

Orientador: Leila Trevisan Braz / Resumo: Polinizações manuais na cultura do meloeiro apresentam taxa de sucesso de cerca de 40%, entretanto, pouco se relata na literatura sobre os aspectos que afetam esta taxa, tornando-a baixa, e como incrementa-la. Este trabalho teve por objetivo estudar a biologia reprodutiva do meloeiro, e estratégias para aumentar a taxa de pegamento de frutos na cultura. Para tal, foram estudados a viabilidade polínica e receptividade estigmática em genótipos de meloeiro ao longo do dia da antese, e, o impacto de diferentes protocolos de polinização na fixação de frutos. Desta forma, foram desenvolvidos três experimentos, um de viabilidade polínica in vitro, e um de receptividade estigmática, estes envolvendo três genótipos de melão rendilhado e cinco horários de coleta de flores, visando entender o comportamento floral do meloeiro ao longo do dia. E um terceiro trabalho, onde foi estudado a fixação de frutos, massa total e massa de mil sementes dos frutos formados sob diferentes protocolos de polinização, para tal empregou-se autopolinizações e hibridações, em dois horários e soluções diretamente nos estigmas da flor hermafrodita, com o objetivo de beneficiar a germinação e estrutura dos tubos polínicos, propiciando fecundações mais eficientes. Após as avaliações, os dados foram submetidos a análise estatística e comparados pelo teste de Tukey a 5% de significância. Foi possível concluir que a viabilidade polínica do meloeiro é afetada pelo genótipo, e os genótipos, JAB 11, JAB 20 e Fantasy, ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Manual pollination in melon crop has a success rate of about 40%, however, little is reported in the literature about the aspects that affect this rate, making it low, and how to increase it. This work aimed to study the reproductive biology of melon, and strategies to increase the fruit set rate in the crop. To this end, we studied the pollen viability and stigmatic receptivity in melon genotypes throughout the day of anthesis, and the impact of different pollination protocols on fruit fixation. Thus, three experiments were carried out, one with in vitro pollen viability and one with stigmatic receptivity, involving three tracery melon genotypes and five flower collection schedules, aiming to understand the floral behavior of melon throughout the day. And a third work, where the fruit fixation, total mass and mass of one thousand seeds of the fruits formed under different pollination protocols was studied. in order to benefit the germination and structure of pollen tubes, providing more efficient fertilization. After the evaluations, the data were submitted to statistical analysis and compared by Tukey test at 5% of significance. It was concluded that the pollen viability of melon is affected by genotype, and the genotypes, JAB 11, JAB 20 and Fantasy, used in this work present viability peak at 09am. Stigmas remain receptive throughout the day of anthesis, allowing pollinations to be made throughout the day if pollen is viable. In JAB 20 hermaphrodite flowers, the applicatio... (Complete abstract click electronic access below) / Mestre