Astrobiology is a multidisciplinary topic that addresses the origin, distribution and evolution of life in the universe. One of the key questions relates to whether life could have evolved on other planetary bodies, and Mars has been the major focus. Biologists contribute to this question by studying the ecology of extreme environments on Earth that share closest analogy to Mars’ past or present environment. In this thesis, molecular-level interrogations were used to address some aspects of microbial biodiversity, ecology and stress tolerance in two such extreme environments. The high-altitude cold and intense UV irradiance of central Tibet was selected as an analogue for Mars surface today, whilst cold alkaline high-carbonate freshwater lakes were chosen as an analogue for Mars’ previous late wet phase. Biological soil crusts from central Tibet supported a diverse microflora and these were variously bacteria or eukarya dominated. The relatively well-developed eukarya-dominated crusts were characterized and showed they comprised of Stichococcus bacillaris, plus alphaproteobacteria, betaproteobacteria, bacteroidetes and gemmatimonadetes. In order to evaluate the diversity of radiation-tolerant taxa in these soils, samples were exposed to ionizing radiation and viability, physiology and phylogenetic identity determined. The most radio-tolerant taxa isolated and characterized were from the radiation tolerant phylum Deinococci (15kGy), whilst a relatively diverse range of Actinobacteria, Bacilli, Cyanobacteria and Proteobacteria were also recovered after exposure to doses up to 10kGy. This implies the high-radiation environment has selected for tolerance among diverse phyla, with tolerances that far exceed environmental exposure. It is not known at this stage if they all employ similar protective strategies. Microbial reefs that have developed in cold alkaline lakes in British Columbia were studied as analogues for a late-wet Mars environment. Molecular ecological analysis revealed that communities consisted largely of of Proteobacteria (alpha), Cyanobacteria (Leptolyngbya) and Acidobacteria, with similarities in community assembly to marine stromatolites. Microbial diversity varied spatially and temporally within microbialites, and indicated that geographically proximal structures can develop with different communities. Significant changes also occur between summer and winter when the lake surface is frozen. Investigation of other nearby lakes with similar geochemistry but not supporting microbialites revealed extensive microbial mats. These developed in the presence of relatively high concentrations of methane or sulfate, and their biodiversity reflected this with several putative methanotrophic and sulphate utilizing taxa identified. No obvious cues that inhibit or promote microbialite formation were observed in this study. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

The main part of the introduction illustrates the health care provision made in the past for workforces of the oil and gas industries functioning in remote places usually associated with an environmental hazard. Much of the past work has been carried out in the North Sea and the provision made there has been reviewed in some detail together with the gradual development of health care in the United Arab Emirates for both the offshore and the onshore oil-related workforces. There follows a short review of the provision made for two analogous situations - Newfoundland and Labrador and the British Antarctic Territories - since the developments there are of direct relevance to the Middle East situation. The main environmental hazard in the Middle East is heat and so the physiology and pathology of thermal balance in man are addressed in some detail. The first study is on the identification of the particular thermal problem which occurs in the offshore workings on the Abu Dhabi oil and gas companies, namely heat cramps. This problems had not been previously identified and the work done in determining its presence and its management is duly reported, indicating the problems of accepting health education material designed for one environment by another. In the development of systems of health care for both oil and non-oil related remote populations, the importance of training of the population at risk has been repeatedly emphasised. The perceived problems in that area are skill retention by laymen and the acceptance of the guidelines of the European and US Resuscitation Councils. A second study was therefore carried out to examine skill retention in laymen together with the feasibility of carrying out resuscitation manoeuvres in high temperatures.

Thesis (Ph.D.)--Biology, Georgia Institute of Technology, 2008. / Committee Chair: Patricia Sobecky; Committee Member: Ellery Ingall; Committee Member: Jim Spain; Committee Member: Martial Taillefert; Committee Member: Thomas DiChristina.

Extreme environments created through natural and anthropogenic processes harbor microbes with diverse physiologies capable of catalyzing chemical reactions which are environmentally beneficial on local and global scales. This work focused on two unique environments, the Gulf of Mexico (GoM) submarine mud volcano systems and the subsurface soils at the Department of Energy s (DOE) Field Research Center (FRC) located in the Oak Ridge National Laboratory Reservation (Oak Ridge, TN). In addition to the physical and chemical extremes present within mud volcano sediments and FRC subsurface soils, these environments are sources of greenhouse gases as well as metal/radionuclide contaminants, respectively. Within the previously uncharacterized mud volcano cold seep sediments, culture-independent analyses of microbial community structure via DNA and RNA clone libraries indicated Gammaproteobacteria and anaerobic methane oxidizing Archaea as the dominant methane oxidizing taxa. Culture-dependent studies of FRC subsurface Arthrobacter and Bacillus isolates demonstrated extensive lateral gene transfer of the PIB-type ATPase metal resistance genes. Additionally, FRC Bacillus and Rahnella isolates demonstrated U(VI) sequestration capabilities as up to 95% soluble U(VI) was immobilization via biogenic phosphate mineral production resulting from constitutive nonspecific phosphohydrolase activity. Findings from these studies identify the prokaryotic diversity within aquatic and terrestrial sediments that contribute to the geochemical cycling of carbon, metals, and radionuclides.

The scope of extreme-environment diving defined within this work encompasses diving modes outside of the generally accepted no-decompression, open-circuit, compressed-air diving limits on selfcontained underwater breathing apparatus (scuba) in temperate or warmer waters. Extreme-environment diving is scientifically and politically interesting. The scientific diving operational safety and medical framework is the cornerstone from which diving takes place in the scientific community. From this effective baseline, as evidenced by decades of very low DCS incidence rates, the question of whether compressed air is the best breathing medium under pressure was addressed with findings indicating that in certain depth ranges a higher fraction of oxygen (while not exceeding a PC 2 of 1.6 ATA) and a lower fraction of nitrogen result in extended bottom times and a more efficient decompression. Extremeenvironment diving under ice presents a set of physiological. equipment, training and operational challenges beyond regular diving that have also been met through almost 50 years of experience as an underwater research tool. Diving modes such as mixed-gas, surface-supplied diving with helmets may mitigate risk factors that the diver incurs as a result of depth, inert gas narcosis or gas consumption. A close approximation of inert gas loading and decompression status monitoring is a function met by dive computers, a necessity in particular when the diver ventures outside of the single-dive profile into the realm of multi-level, multi-day repetitive diving or decompression diving. The monitoring of decompression status in extreme environments is now done exclusively through the use of dive computers and evaluations of the performance of regulators under ice have determined the characteristics of the next generation of life-support equipment for extreme-environment diving for science. These polar, deep and contaminated water environments require risk assessment that analyzes hazards such as cold stress, hydration, overheating, narcosis, equipment performance and decompression sickness. Scientific diving is a valuable research tool that has become an integral methodology in the pursuit of scientific questions in extreme environments of polar regions, in contaminated waters, and at depth.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Mark G. Allen; Committee Co-Chair: Dr. Oliver Brand; Committee Member: Dr. Andrew Peterson; Committee Member: Dr. Elliot Chaikof; Committee Member: Dr. Gregory Durgin; Committee Member: Dr. Robert Butera.

Philosophiae Doctor - PhD / There are approximately 10³¹ bacteriophages in the biosphere, outnumbering bacteria 10:1, hence, the dynamic and specific nature of phage-host interactions exerts significant influence on microbial communities. Bacteriophages also represent the reservoir of the highest known genetic diversity making them a potential source of novel biotechnological products. However, the isolation of novel bacteriophages is limited by the observation that less than 1% of bacterial hosts have been cultured. This study aimed to bypass this problem by developing novel culture independent approaches to improve our ability to isolate novel phage-host pairs. Samples were collected from an abandoned copper prospecting site near the Gobabeb Desert Research and Training Station and a Salt lake located in the Swakopmund region of the Namibian desert. Two approaches were explored in this study namely viral tagging and reverse metaviromics. For viral tagging, fluorescently labelling the environmental phage fraction before challenging the environmental bacterial fraction with tagged phages proved difficult. This was most likely due to the complex interaction of the labelling agent with phages and requires further studies. For the reverse metaviromics approach, total DNA from the environmental phage fractions was extracted, sequenced and analyzed for novel phages. Analysis of the phage diversity showed that the copper site was dominated by tailed viruses as has been shown for other extreme arid environments. However, the saline site was atypical of marine environments, with tailed viruses being the most abundant, suggesting that the diversity present is not only driven by salinity. Using the metaviromic sequence data to guide the selection of potential bacterial hosts, two strategies were employed. In the first, putative hosts were predicted based on similarity of phage sequences to those identified in databases. Media targeting these specific genera were employed, 8 bacterial species were isolated and based on 16S rRNA similarity to the closest known species were identified as Halomonas caseinilytica, Halomonas eurihalina, Halomonas sinaiensis, Idiomarina loihiensis, Marinobacter xestospongiae, Virgibacillus salarius and two Salinivibrio species. The 16S rRNA analysis also suggested that H. sinaiensis, V. salarius and both Salinivibrio species are novel. All 8 isolates were challenged with the environmental phage fraction. A novel phage, SMHB1, was isolated on one of the Salinivibrio spp. and is only the second characterized phage ever described for this genus. SMHB1 is a 32 kb myovirus, with a head diameter of 56 nm, and a tail length of 106 nm. The second approach involved the design of fluorescently labelled probes targeting phages identified from the metaviromic sequence data. In a control E. coli system to detect cloned phage DNA fragments, 87% of the interrogated cells showed significant hybridization of the phage specific probe to the target. The optimized method was applied to a simulated environmental bacterial fraction and a detection limit of 1:100 was observed for the bacteria containing the phage DNA fragment of interest. This study demonstrates the possibility of improving the specificity of isolating phage-host pairs in a culture-independent manner by incorporating sequence data in the experimental design; and contributes to our knowledge of the phage diversity of an understudied extreme environment.

>Magister Scientiae - MSc / Microorganisms of the class Actinobacteria and domain Archaea are interesting from a biotechnological perspective owing to their metabolic attributes as producers of secondary metabolites and resilience under harsh environmental conditions respectively. Lake Magadi is a soda lake well studied in terms of its geology and limnology. Research attention has also been drawn to the microbial populations which thrive in this unique habitat but currently there are no reports on the assessment of its microflora using molecular methods. This study aimed to assess the actinobacterial and archaeal communities within Lake Magadi, Kenya a hypersaline –highly alkaline habitat using metagenomic methods as a preliminary study to identify potential candidates for exploitative biology Samples from two sites dubbed Lake Magadi station 2 (LM2) and Lake Magadi salt pan 4 (LMS4) within the Lake Magadi were analyzed using the 16S rRNA gene as a phylogenetic marker. Cluster analysis of taxon-specific 16S rDNA PCR-DGGE profiles revealed moderately heterogeneous actinobacterial and archaeal populations across the sample sites under investigation which is probably a reflection of the differences in abiotic conditions at the study sites. This observation was also confirmed from the multi-dimensional scaling (MDS) plot. PCR-based clonal libraries of actinobacterial and archaeal communities of both study sites retrieved a total of thirty-two clones (twenty actinobacterial and twelve archaeal) were sequenced. Analysis of the sequences revealed cultured and uncultured signatures of microorganisms typical of hypersaline and or highly alkaline niches. A few (3) sequences presented novelty (<96%) in identities with any previously identified organism. It was concluded that the species dominance at site LMS4 [situated within the salt flats of Lake Magadi and site for exploration of trona and its mineralized extensions (nacholite and gayllusite)] is likely to be dictated by anthropogenic stress since most of the microbial signals associated with the study site are typical of saline and or alkaline environmental samples exposed to especially mining but also agricultural and waste management practices. Isolation studies also revealed previously identified strains peculiar to hypersaline brines and sediments. The strains retrieved were affiliated to the taxonomically diverse genus Bacillus and Halomonas sp. The true applications and potential opportunities these isolates have for biotechnology have been well documented. Observations made from the culture dependent and culture independent methods suggests strongly that study site LMS4 is subjected to environmental conditions more severe than at site LM2. This study is a guide for future studies as it provides primary information on the haloalkaliphilic representatives of the actinobacteria phylum and domain Archaea within the soda lake environment. It can serve as a pedestal for investigation into the molecular machinery that supports the haloalkaliphilic lifestyles of inhabiting microorganisms and consequently give leads as to how they can be commercially exploited.

Research purpose The purpose of this study is to examine the extent to which both employees and leaders in extreme environments perceive the same levels of safety participation. Furthermore, this study examines the association between empowering leadership and team performance as well as empowering leadership and safety participation. Research design, approach and methods This study follows a quantitative approach as its main purpose is to establish relationships between constructs. As such, correlations and multiple regression analyses were conducted. Convenience sampling was applied to obtain the data. Firefighters and their immediate line officers (lieutenants) were surveyed. Five fire departments in small to medium cities were chosen in the Great Lakes and south-eastern regions in the United States (US). Questionnaires were distributed to 263 firemen, of which 186 were firefighters and 78 were their line officers/lieutenants. Main findings Results indicated that a positive association does not exist between firefighters' perceptions of safety participation and their leaders' perception of safety participation when control variables are added. Therefore, no significant relationship exists between firefighters' perceptions of safety participation and their leaders' perception of safety participation. Furthermore, the results also showed a positive association does not exist between empowering leadership and safety participation when control variables are added. Consequently, no significant relationship exists between firefighters' reports of empowering leadership and lieutenants' reports of safety participation. Lastly, regarding empowering leadership and team performance, the results did not support a direct relationship between these two constructs. Limitations The results should be interpreted bearing in mind that they are applicable to the United States of America and may not be generalised to the South African context. Additionally, very little research has been conducted on empowering leadership and safety behaviour in extreme environments, and therefore the literature review was limited to other organisational environments. Lastly, only three cultural groups (White, Black and Hispanic) and only men participated in this study, so results may not be generalisable to other demographic groups. The study was only positioned in extreme environments, specifically in firefighting, therefore it is unclear whether the results can be generalised to other work environments. Future Research It is suggested that this study is replicated, firstly because little research has been done in extreme environments but, secondly, that it also be specifically replicated in South Africa. Indicated by the data, a lieutenant's age has a positive association with how he perceives his team's safety participation. This could be due to various reasons. For example, the more experienced the lieutenant the more comfortable he gets towards the extreme environment. Lastly, it is suggested that research is conducted to determine other leadership styles which could be effective in extreme environments. Conclusion Insight was given into the empowering leadership style in terms of team performance and safety behaviour. Furthermore, the relation between firefighters' perceptions of safety participation and their leaders' perceptions of safety participation was not confirmed. / Dissertation (MCom)--University of Pretoria, 2017. / Human Resource Management / MCom / Unrestricted

Wearable computers allow users the freedom to work in any environment including hazardous environments that may require protective clothing. Past research has shown that protective clothing interferes with manual materials handling tasks, medical tasks, and manual dexterity tasks. However, little information exists regarding how protective clothing affects task performance with wearable input devices. As a result, a study was conducted to address this issue and offer recommendations to enhance the compatibility of chemical protective clothing and wearable input devices. Sixteen active-duty soldiers performed a text-entry task with a wearable mouse and touch pad, while bare handed, wearing 7-mil, 14-mil, and 25-mil chemical protective gloves, wearing a respirator alone, and wearing the respirator and each of three gloves. Upon completion of the experiment, participants rated task difficulty, confidence using the input device, and input device preference. Task completion times were 9% slower with the 25-mil glove than the 7-mil glove. Text entry was not perceived as difficult when bare handed, or wearing the 7-mil and 14-mil gloves, suggesting that thin chemical protective gloves (i.e. 7-mil and 14-mil) are more suitable than thicker gloves for use with wearable input devices. When using the touch pad, task completion times were 17% faster than when using the mouse. Subjective ratings of difficulty, confidence, and preference provide strong support for the use of a touch pad input device rather than a mouse. / Master of Science