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68 records were found.

Antarctic ecosystems (such as the ponds by Bratina Island, Antarctica) provide an excellent opportunity to examine organisms that can live in one of the most extreme and geochemically varied environments in the world. These ponds are of interest as each one can vary greatly in size, depth, and age as well as profiles of dissolved oxygen, metal concentrations, pH and salinity. Even within ponds geochemically distinct stratified layers can form which can greatly influence their microbial communities. There are a number of studies which indicate that microbial populations found in Antarctic ponds will be highly diverse and variable due to the uniqueness of the environment. This study aims to increase our knowledge of microbial biodiversity and the environmental factors which structure them, in particular the stratification transition zone...
The Antarctic Dry Valleys are characterized by extremely low temperatures, arid conditions, high salinity and virtual absence of plants. Therefore, food webs of these microbially dominated soils are among the simplest on earth making these mineral soils a perfect model to study microbial biogeography. This study aims to characterize the distribution and diversity of Archaea within the Dry Valleys as part of the New Zealand Terrestrial Antarctic Biocomplexity Survey (NZTABS). An international multidisciplinary organization focusing on biotic organisms, community structure and their functional linkage to determine what environmental factors drive biocomplexity. Archaea are so far the least known members of the microbial community with only a few successful attempts at detection indicating a patchy distribution and low diversity. A wide r...
The Beardmore Glacier region of the Central Transantarctic Mountains (CTAM), approximately 600 km south of the McMurdo Dry Valleys (MDV), has been studied to a much lesser extent than the accessible MDV and other regions of the continent. The CTAM were visited in the 2010/2011 austral summer, and two concurrent studies undertaken; these are presented in the form of manuscripts for publication in peer-reviewed journals, as a thesis by publication. Soil chronosequences in three of the largest ice-free areas (Ong Valley, Mount Achernar, and the Dominion Range), at altitudes above 1600 m along the polar plateau margin, were examined. Transects perpendicular to the current ice edge reveal a gradual increase in soil depth (from 2 cm to > 80 cm to underlying ice), weathering, horizonation, salt content, and a decrease in pH; all of these fact...
Mount Erebus is the most active volcano on the Antarctic continent, and has the most geographically and physically isolated geothermal soil on Earth. It is exposed to some of the most extreme environmental conditions on the planet. Recent preliminary genetic analysis of the microbial community present in the 65??C subsurface soil of Tramway Ridge, Mount Erebus has revealed a unique thermophilic microbial system, with the dominant members possessing little genetic similarity to any known bacteria. The aim of this project was to apply a range of techniques to investigate metabolic and physiological requirements of this poorly understood microbial system. The study included physical-chemical soil surveying, strategic cultivation, community based phenotypic arrays, nutritional enrichment experiments and pyrosequencing. This multifaceted, m...
Pleurobranchaea maculata (grey-side gilled sea slug) was discovered to contain the neurotoxin tetrodotoxin (TTX) in 2009 after a spate of dog poisoning cases on the beaches of Auckland, New Zealand. One of the great mysteries of TTX is the lack of conclusive evidence about its ultimate origin. Possible sources postulated have included both endogenous and exogenous. Additionally, within a species both toxic and non-toxic strains exist. For example, in New Zealand, P. maculate from the North Island are toxic, whereas P. maculata from the South Island are not. The overarching hypothesis of this Master???s project is that TTX has a dietary origin in P. maculata and that they will preferentially feed on TTX-containing food. This Master???s thesis aimed to test this hypothesis through three distinct aims: (1) To develop a non-lethal biopsy m...
Cyanobacteria (blue-green algae) are a group of ancient prokaryotic organisms which have become synonymous with water quality deterioration. An array of compounds is produced by aquatic cyanobacteria, the largest group being the oligopeptides. A major class of cyanobacterial oligopeptides are the microcystins; cyclic heptapeptides which contain the unique amino acid Adda (3 amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid). Due to their ability to inhibit protein phosphatases 1 and 2A and as they are concentrated in the liver, microcystins can be highly toxic to animals. Anabaenopeptins are cyclic hexapeptides which contain a carbonyl-linked sidechain amino acid and a ring which is cyclised through the sidechain amine of the position two D-lysine. Matrix-assisted laser desorption/ionisation-time of flight mass spectromet...
Invasive species are widely recognised as one of the major threats to marine biodiversity worldwide. With increasingly faster and more frequent transoceanic shipping, propagule pressure in the marine environment is likely to further increase, leading to a need for effective strategies for the early detection, prevention and control of marine invasive species. However, such strategies are often difficult to implement as many marine species cannot be accurately categorised as either native or non-native. For these reasons molecular genetic methods have increasingly been utilised for the study of marine invasive species. The potential for molecular data to enhance traditional morphology-based information is recognised and there has been huge progress in the application of molecular genetic methods to the study of marine bioinvasions in th...
A unique community of bacteria colonizes the dorsal integument of the polychaete annelid Alvinella pompejana, which inhabits the high-temperature environments of active deep-sea hydrothermal vents along the East Pacific Rise. The composition of this bacterial community was characterized in previous studies by using a 16S rRNA gene clone library and in situ hybridization with oligonucleotide probes. In the present study, a pair of PCR primers (P94-F and P93-R) were used to amplify a segment of the dissimilatory bisulfite reductase gene from DNA isolated from the community of bacteria associated with A. pompejana. The goal was to assess the presence and diversity of bacteria with the capacity to use sulfate as a terminal electron acceptor. A clone library of bisulfite reductase gene PCR products was constructed and characterized by restr...
A highly integrated, morphologically diverse bacterial community is associated with the dorsal surface of Alvinella pompejana, a polychaetous annelid that inhabits active high-temperature deep-sea hydrothermal vent sites along the East Pacific Rise (EPR). Analysis of a previously prepared bacterial 16S ribosomal DNA (rDNA) library identified a spirochete most closely related to an endosymbiont of the oligochete Olavius loisae. This spirochete phylotype (spirochete A) comprised only 2.2% of the 16S rDNA clone library but appeared to be much more dominant when the same sample was analyzed by denaturing gradient gel electrophoresis (DGGE) and the terminal restriction fragment length polymorphism procedure (12 to 18%). PCR amplification of the community with spirochete-specific primers used in conjunction with DGGE analysis identified two ...
This paper describes a method used to model relative wetness for part of the Antarctic Dry Valleys using Geographic Information Systems (GIS) and remote sensing. The model produces a relative index of liquid water availability using variables that influence the volume and distribution of water. Remote sensing using Moderate Resolution Imaging Spectroradiometer (MODIS) images collected over four years is used to calculate an average index of snow cover and this is combined with other water sources such as glaciers and lakes. This water source model is then used to weight a hydrological flow accumulation model that uses slope derived from Light Detection and Ranging (LIDAR) elevation data. The resulting wetness index is validated using three-dimensional visualization and a comparison with a high-resolution Advanced Land Observing Satelli...
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