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Abstract Background Wolbachia incompatible insect technique (IIT) programs have been shown in field trials to be highly effective in suppressing populations of mosquitoes that carry diseases such as dengue, chikungunya, and Zika. However, the frequent and repeated release of Wolbachia-infected male mosquitoes makes such programs resource-intensive. While the need for optimization is recognized, potential strategies to optimize releases and reduce resource utilization have not been fully explored. Results We developed a process-based model to study the spatio-temporal metapopulation dynamics of mosquitoes in a Wolbachia IIT program, which explicitly incorporates climatic influence in mosquito life-history traits. We then used the model to simulate various scale-down and redistribution strategies to optimize the existing program in Singapore. Specifically, the model was used to study the trade-offs between the intervention efficacy outcomes and resource requirements of various release program strategies, such as the total number of release events and the number of mosquitoes released. We found that scaling down releases in existing sites from twice a week to only once a week yielded small changes in suppression efficacy (from 87 to 80%), while requiring 44% fewer mosquitoes and release events. Additionally, redistributing mosquitoes from already suppressed areas and releasing them in new areas once a week led to a greater total suppressive efficacy (83% compared to 61%) while also yielding a 16% and 14% reduction in the number of mosquitoes and release events required, respectively. Conclusions Both scale-down and redistribution strategies can be implemented to significantly reduce program resource requirements without compromising the suppressive efficacy of IIT. These findings will inform planners on ways to optimize existing and future IIT programs, potentially allowing for the wider adoption of this method for mosquito-borne disease control.

Background: Wolbachia incompatible insect technique (IIT) programs have been shown in field trials to be highly effective in suppressing populations of mosquitoes that carry diseases such as dengue, chikungunya, and Zika. However, the frequent and repeated release of Wolbachia-infected male mosquitoes makes such programs resource-intensive. While the need for optimization is recognized, potential strategies to optimize releases and reduce resource utilization have not been fully explored. Results: We developed a process-based model to study the spatio-temporal metapopulation dynamics of mosquitoes in a Wolbachia IIT program, which explicitly incorporates climatic influence in mosquito life-history traits. We then used the model to simulate various scale-down and redistribution strategies to optimize the existing program in Singapore. Specifically, the model was used to study the trade-offs between the intervention efficacy outcomes and resource requirements of various release program strategies, such as the total number of release events and the number of mosquitoes released. We found that scaling down releases in existing sites from twice a week to only once a week yielded small changes in suppression efficacy (from 87 to 80%), while requiring 44% fewer mosquitoes and release events. Additionally, redistributing mosquitoes from already suppressed areas and releasing them in new areas once a week led to a greater total suppressive efficacy (83% compared to 61%) while also yielding a 16% and 14% reduction in the number of mosquitoes and release events required, respectively. Conclusions: Both scale-down and redistribution strategies can be implemented to significantly reduce program resource requirements without compromising the suppressive efficacy of IIT. These findings will inform planners on ways to optimize existing and future IIT programs, potentially allowing for the wider adoption of this method for mosquito-borne disease control. [ABSTRACT FROM AUTHOR]

The key building blocks for life on Mars could be preserved within potentially habitable paleo-depositional settings with their detection possible by utilizing mid-infrared spectroscopy; however, a definite identification and confirmation of organic or even biological origin will require the samples to be returned to Earth. In the present study, Fourier-transform infrared (FTIR) spectroscopic techniques were used to characterize both mineralogical and organic materials within Mars dust simulant JSC Mars-1 and ancient Antarctic cyanobacterial microbial mats from 1901 to 1904 Discovery Expedition. When FTIR spectroscopy is applied to cyanobacterial microbial mat communities, the resulting spectra will reflect the average biochemical composition of the mats rather than taxa-specific spectral patterns of the individual organisms and can thus be considered as a total chemical analysis of the mat colony. This study also highlights the potential difficulties in the detection of these communities on Mars and which spectral biosignatures will be most detectable within geological substrates. Through the creation and analysis of a suite of dried microbial mat material and Martian dust simulant mixtures, the spectral signatures and wavenumber positions of CH x aliphatic hydrocarbons and the C-O and O-H bands of polysaccharides remained detectable and may be detectable within sample mixtures obtained through Mars Sample Return activities.

Water present on early Mars is often assumed to have been habitable. In this study, experiments were performed to investigate the habitability of well-defined putative martian fluids and to identify the accompanying potential formation of biosignatures. Simulated martian environments were developed by combining martian fluid and regolith simulants based on the chemistry of the Rocknest sand shadow at Gale Crater. The simulated chemical environment was inoculated with terrestrial anoxic sediment from the Pyefleet mudflats (United Kingdom). These enrichments were cultured for 28 days and subsequently subcultured seven times to ensure that the microbial community was solely grown on the defined, simulated chemistry. The impact of the simulated chemistries on the microbial community was assessed by cell counts and sequencing of 16S rRNA gene profiles. Associated changes to the fluid and precipitate chemistries were established by using ICP-OES, IC, FTIR, and NIR. The fluids were confirmed as habitable, with the enriched microbial community showing a reduction in abundance and diversity over multiple subcultures relating to the selection of specific metabolic groups. The final community comprised sulfate-reducing, acetogenic, and other anaerobic and fermentative bacteria. Geochemical characterization and modeling of the simulant and fluid chemistries identified clear differences between the biotic and abiotic experiments. These differences included the elimination of sulfur owing to the presence of sulfate-reducing bacteria and more general changes in pH associated with actively respiring cells that impacted the mineral assemblages formed. This study confirmed that a system simulating the fluid chemistry of Gale Crater could support a microbial community and that variation in chemistries under biotic and abiotic conditions can be used to inform future life-detection missions.

Meteorites that fall to Earth quickly become contaminated with terrestrial microorganisms. These meteorites are out of chemical equilibrium in the environments where they fall, and equilibration promotes formation of low-temperature alteration minerals that can entomb contaminant microorganisms and thus preserve them as microfossils. Given the well-understood chemistry of meteorites and their recent discovery on Mars by rovers, a similarly weathered meteorite on Mars could preserve organic and fossil evidence of a putative past biosphere at the martian surface. Here, we used several techniques to assess the potential of alteration minerals to preserve microfossils and biogenic organics in terrestrially weathered ordinary chondrites from the Nullarbor Plain, Australia. We used acid etching of ordinary chondrites to reveal entombed fungal hyphae, modern biofilms, and diatoms within alteration minerals. We employed synchrotron X-ray fluorescence microscopy of alteration mineral veins to map the distribution of redox-sensitive elements of relevance to chemolithotrophic organisms, such as Mn-cycling bacteria. We assessed the biogenicity of fungal hyphae within alteration veins using a combination of Fourier-transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry, which showed that alteration minerals sequester and preserve organic molecules at various levels of decomposition. Our combined analyses results show that fossil microorganisms and the organic molecules they produce are preserved within calcite-gypsum admixtures in meteorites. Furthermore, the distributions of redox-sensitive elements ( e.g. , Mn) within alteration minerals are localized, which qualitatively suggests that climatically or microbially facilitated element mobilization occurred during the meteorite's residency on Earth. If returned as part of a sample suite from the martian surface, ordinary chondrites could preserve similar, recognizable evidence of putative past life and/or environmental change.

The detection of potential biosignatures with mineral matrices is part of a multifaceted approach in the search for life on other planetary bodies. The 2020 ExoMars Rosalind Franklin rover includes within its payload three IR spectrometers in the form of ISEM (Infrared Spectrometer for ExoMars), MicrOmega, and Ma-MISS (Mars Multispectral Imager for Subsurface Studies). The use of this technique in the detection and characterization of biosignatures is of great value. Organic materials are often co-deposited in terrestrial evaporites and as such have been proposed as relevant analogs in the search for life on Mars. This study focuses on Ca-sulfates collected from the hypersaline Tírez Lake in Spain. Mid infrared and visible near infrared analysis of soils, salt crusts, and crystals with green and red layering indicative of microbial colonization of the samples was acquired from across the lake and identified the main mineral to be gypsum with inputs of carbonate and silica. Organic functional groups that could be attributed to amides and carboxylic acids were identified as well as chlorophyll; however, due to the strong mineralogical absorptions observed, these were hard to unambiguously discern. Taxonomical assignment demonstrated that the archaeal community within the samples was dominated by the halophilic extremophile Halobacteriaceae while the bacterial community was dominated by the class Nocardiaceae. The results of this research highlight that sulfates on Mars are a mixed blessing, acting as an effective host for organic matter preservation but also a material that masks the presence of organic functional groups when analyzed with spectroscopic tools similar to those due to fly on the 2020 ExoMars rover. A suite of complementary analytical techniques therefore should be used to support the spectral identification of any candidate extraterrestrial biosignatures.

Discovery of a remnant habitable environment by the Mars Science Laboratory in the sedimentary record of Gale Crater has reinvigorated the search for evidence of martian life. In this study, we used a simulated martian mudstone material, based on data from Gale Crater, that was inoculated and cultured over several months and then dried and pressed. The simulated mudstone was analysed with a range of techniques to investigate the detectability of biosignatures. Cell counting and DNA extraction showed a diverse but low biomass microbial community that was highly dispersed. Pellets were analysed with bulk Elemental Analysis - Isotope Ratio Mass Spectrometry (EA-IRMS), high-resolution Laser-ablation Ionisation Mass Spectrometry (LIMS), Raman spectroscopy and Fourier Transform InfraRed (FTIR) spectroscopy, which are all techniques of relevance to current and future space missions. Bulk analytical techniques were unable to differentiate between inoculated samples and abiotic controls, despite total levels of organic carbon comparable with that of the martian surface. Raman spectroscopy, FTIR spectroscopy and LIMS, which are high sensitivity techniques that provide chemical information at high spatial resolution, retrieved presumptive biosignatures but these remained ambiguous and the sedimentary matrix presented challenges for all techniques. This suggests challenges for detecting definitive evidence for life, both in the simulated lacustrine environment via standard microbiological techniques and in the simulated mudstone via analytical techniques with relevance to robotic missions. Our study suggests that multiple co-incident high-sensitivity techniques that can scan the same micrometre-scale spots are required to unambiguously detect biosignatures, but the spatial coverage of these techniques needs to be high enough not to miss individual cellular-scale structures in the matrix.

Cryptoendolithic lichen communities of the Dry Valleys, Antarctica, survive in an extremely inhospitable environment, finding refuge in microscopic niches where conditions suitable for life exist. Such "within-rock" communities may have evolved on Mars when conditions for life on the surface deteriorated to such an extent that they could no longer survive. Fourier transform infrared spectroscopy of unprepared whole-rock Antarctic Beacon sandstones was used to vertically profile molecular vibrations of fatty acids, proteins, and carboxylic acids created by endolithic communities. Spectral biosignatures were found localized to lichen-rich areas and were absent in crustal regions and the bulk rock substrate. These cryptoendolithic profiles will aid similar spectroscopic investigations of organic biosignatures during future Martian subsurface studies and will help in the identification of similar communities in other localities across the Earth.

Microorganisms have been found to etch volcanic glass within volcaniclastic deposits from the Ontong Java Plateau, creating micron-sized tunnels and pits. The fossil record of such bioalteration textures is interpreted to extend back ∼3.5 billion years to include meta-volcanic glass from ophiolites and Precambrian greenstone belts. Bioalteration features within glass clasts from Leg 192 of the Ocean Drilling Program were investigated through optical microscopy and Fourier transform infrared (FTIR) spectroscopy of petrographic thin sections. Extended depth of focus optical microscopic imaging was used to identify bioalteration tubules within the samples and later combined with FTIR spectroscopy to study the organic molecules present within tubule clusters. The tubule-rich areas are characterized by absorption bands indicative of aliphatic hydrocarbons, amides, esters, and carboxylic groups. FTIR analysis of the tubule-free areas in the cores of glass clasts indicated that they were free of organics. This study further constrains the nature of the carbon compounds preserved within the tubules and supports previous studies that suggest the tubules formed through microbial activity.

One of the keys to understanding and identifying life on other planets is to study the preservation of organic compounds and their precursor micro-organisms on Earth. Rio Tinto in southwestern Spain is a well documented site of microbial preservation within iron sulphates and iron oxides over a period of 2.1 Ma. This study has investigated the preservation of filamentous iron oxidising bacteria and organics through optical microscopy, scanning electron microscopy (SEM) and Fourier transform infra-red (FTIR) spectroscopy, from laboratory cultures of natural samples to contemporary natural materials to million-year old river terraces. Up to 40% elemental carbon and >7% nitrogen has been identified within microbial filaments and cell clusters in all samples through SEM EDS analyses. FTIR spectroscopy identified C-H(x) absorption bands between 2960 and 2800 cm(-1), Amide I and II absorption bands at 1656 and 1535 cm(-1), respectively and functional group vibrations from within nucleic acids at 917, 1016 and 1124 cm(-1). Absorption bands tracing the diagenetic transformation of jarosite to goethite to hematite through the samples are also identified. This combination of mineralogy, microbial morphology and biomolecular evidence allows us to further understand how organic fossils are created and preserved in iron-rich environments, and ultimately will aid in the search for the earliest life on Earth and potential organics on Mars., (© 2011 Blackwell Publishing Ltd.)

Knowledge of ancient terrestrial hydrothermal systems-how they preserve biological information and how this information can be detected-is important in unraveling the history of life on Earth and, perhaps, that of extinct life on Mars. The Rhynie Chert in Scotland was originally deposited as siliceous sinter from Early Devonian hot springs and contains exceptionally well-preserved fossils of some of the earliest plants and animals to colonize the land. The aim of this study was to identify biomolecules within the samples through Fourier transform infrared (FTIR) spectroscopy and aid current techniques in identification of ancient hot spring deposits and their biological components on Mars. Floral and faunal fossils within the Rhynie Chert are commonly known; but new, FTIR spectroscopic analyses of these fossils has allowed for identification of biomolecules such as aliphatic hydrocarbons and OH molecules that are potentially derived from the fossilized biota and their environment. Gas chromatograph-mass spectrometer (GCMS) data were used to identify n-alkanes; however, this alone cannot be related to the samples' biota. Silicified microfossils are more resistant to weathering or dissolution, which renders them more readily preservable over time. This is of particular interest in astropaleontological research, considering the similarities in the early evolution of Mars and Earth.

Objective: A survey of clinical laboratories was conducted to capture information about quality indicators in use within the state of Arizona. This information was then used to determine which quality indicators are applicable across the spectrum of clinical laboratories making them suitable for benchmarking laboratory performance. The objectives of this study were also to heighten awareness of benchmarking practices for clinical laboratory managers and laboratory quality assurance personnel, to develop objective methods of quality monitoring for performance improvement, and to encourage collaboration between laboratories and accreditation agencies., Methods: A review of the current literature was conducted to assess the status of benchmarking within the clinical laboratory. Data were also obtained from the Centers for Medicare & Medicaid Services (CMS) about all licensed clinical laboratories in Arizona. A mail survey was then created and conducted to investigate the use of clinical laboratory quality indicators in Arizona., Setting and Participants: A paper survey was mailed to a representative sample of clinical laboratory managers included in the CMS licensed laboratories listing for the state of Arizona., Main Outcome Measures: The selected sample was surveyed by mail and validation testing of the survey was conducted using the t-test. The compiled survey data is also presented in the form of histograms., Results: Applying the t-test to the sample vs. population data proved that the sample was not a very good representation of the population and a better selection method should be used in future studies. Of the 319 of 3198 clinical laboratories randomly selected to receive the survey, 21 (6.58% of the sample or 0.66% of the population) responded with completed surveys. The information received from the respondents revealed a relationship between test volume and the number of indicators being monitored by clinical laboratories, the preference of indicators being monitored by those laboratories, the size of the laboratories where the majority of benchmarking is occurring, and a link between accrediting agencies and benchmarking activities., Conclusion: The survey proved that quality indicators are used for quality improvement purposes within the clinical laboratory; although it also showed that the industry still does not have a standardized approach to the use of quality indicators for benchmarking performance against other laboratories.