The Past, Present, and Future of Research on Interviewer Effects

Interviewer-administered surveys are a primary method of collecting information from populations across the United States and the world. Various types of interviewer-administered surveys exist, including large-scale government surveys that monitor populations (e.g., the Current Population Survey), surveys used by the academic community to understand what people think and do (e.g., the General Social Survey), and surveys designed to gauge public opinion at a particular time point (e.g., the Gallup Daily Tracking Poll). Interviewers participate in these data collection efforts in a multitude of ways, including creating lists of housing units for sampling, persuading sampled units to participate, and administering survey questions (Morton-Williams 1993). In an increasing number of surveys, interviewers are also tasked with collecting blood, saliva, and other biomeasures, and asking survey respondents for consent to link survey data to administrative records (Sakshaug 2013). Interviewers are also used in mixed mode surveys to recruit and interview non respondents after less expensive modes like mail and web have failed (e.g., the American Community Survey and the Agricultural Resource Management Survey; de Leeuw 2005; Dillman, Smyth and Christian 2014; Olson et al. 2019). In completing these varied tasks, interviewers affect survey costs and coverage, nonresponse, measurement, and processing errors (Schaeffer, Dykema and Maynard 2010; West and Blom 2017)

Isotopic and chemical assessment of the dynamics of methane sources and microbial cycling during early development of an oil sands pit lake

Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).NSERC (CRDPJ 488301-15) and COSIA; FONDECYT, Grant 11191138 (ANID Chile); COPAS COASTAL ANID, FB210021Peer ReviewedWater-capped tailings technology (WCTT) is a key component of the reclamation strategies in the Athabasca oil sands region (AOSR) of northeastern Alberta, Canada. The release of microbial methane from tailings emplaced within oil sands pit lakes, and its subsequent microbial oxidation, could inhibit the development of persistent oxygen concentrations within the water column, which are critical to the success of this reclamation approach. Here, we describe the results of a four-year (2015–2018) chemical and isotopic (δ13C) investigation into the dynamics of microbial methane cycling within Base Mine Lake (BML), the first full-scale pit lake commissioned in the AOSR. Overall, the water-column methane concentrations decreased over the course of the study, though this was dynamic both seasonally and annually. Phospholipid fatty acid (PLFA) distributions and δ13C demonstrated that dissolved methane, primarily input via fluid fine tailings (FFT) porewater advection, was oxidized by the water column microbial community at all sampling times. Modeling and under-ice observations indicated that the dissolution of methane from bubbles during ebullition, or when trapped beneath ice, was also an important source of dissolved methane. The addition of alum to BML in the fall of 2016 impacted the microbial cycling in BML, leading to decreased methane oxidation rates, the short-term dominance of a phototrophic community, and longer-term shifts in the microbial community metabolism. Overall, our results highlight a need to understand the dynamic nature of these microbial communities and the impact of perturbations on the associated biogeochemical cycling within oil sands pit lakes

A Low-Diversity Microbiota Inhabits Extreme Terrestrial Basaltic Terrains and Their Fumaroles : Implications for the Exploration of Mars

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.Peer reviewe

Sample Collection and Return from Mars: Optimising Sample Collection Based on the Microbial Ecology of Terrestrial Volcanic Environments

With no large-scale granitic continental crust, all environments on Mars are fundamentally derived from basaltic sources or, in the case of environments such as ices, evaporitic, and sedimentary deposits, influenced by the composition of the volcanic crust. Therefore, the selection of samples on Mars by robots and humans for investigating habitability or testing for the presence of life should be guided by our understanding of the microbial ecology of volcanic terrains on the Earth. In this paper, we discuss the microbial ecology of volcanic rocks and hydrothermal systems on the Earth. We draw on microbiological investigations of volcanic environments accomplished both by microbiology-focused studies and Mars analog studies such as the NASA BASALT project. A synthesis of these data emphasises a number of common patterns that include: (1) the heterogeneous distribution of biomass and diversity in all studied materials, (2) physical, chemical, and biological factors that can cause heterogeneous microbial biomass and diversity from sub-millimetre scales to kilometre scales, (3) the difficulty of a priori prediction of which organisms will colonise given materials, and (4) the potential for samples that are habitable, but contain no evidence of a biota. From these observations, we suggest an idealised strategy for sample collection. It includes: (1) collection of multiple samples in any given material type (similar to 9 or more samples), (2) collection of a coherent sample of sufficient size (similar to 10 cm(3)) that takes into account observed heterogeneities in microbial distribution in these materials on Earth, and (3) collection of multiple sample suites in the same material across large spatial scales. We suggest that a microbial ecology-driven strategy for investigating the habitability and presence of life on Mars is likely to yield the most promising sample set of the greatest use to the largest number of astrobiologists and planetary scientists

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Investigating intra-bone isotopic variations in bioapatite using IR-laser ablation and micromilling: Implications for identifying diagenesis?

The potential of in situ microsampling (micromilling and IR-laser ablation) to detect intra-sample isotopic variation resulting from diagenesis and/or natural remodeling of bone was examined in this study. Modern sheep bones were exposed to microbial populations to induce diagenesis and the δC and δO values of bioapatite structural carbonate and phosphate were determined for these samples and for diagenetically modified archaeological samples from three different environments. No significant differences were found between the δC or δO values of microbially colonized and uncolonized areas on the modern bone surfaces, or between well-preserved and poorly preserved regions of the archaeological material. However, high degree of intra-sample variation was observed in δ-values obtained using IR-laser ablation, some of which arose from methodological challenges associated with this method. Further, δC values obtained using IR-laser ablation were lower than those acquired by conventional analysis, likely because of contamination from organic matter in the samples. Isotopic compositions of structural carbonate samples obtained by micromilling were less variable. For both methods, however, significant differences in δC and δO values were observed for different bone surfaces. These variations may indicate differences in the isotopic compositions of food and water incorporated into osteons over a lifetime, and illustrate the relationship between bone remodelling and isotopic heterogeneity in bone. Overall, our results highlight the difficulties of using the IR-laser ablation method for measuring isotopic compositions of bone

Robust, high-productivity phototrophic carbon capture at high pH and alkalinity using natural microbial communities

Abstract Background Bioenergy with carbon capture and storage (BECCS) has come to be seen as one of the most viable technologies to provide the negative carbon dioxide emissions needed to constrain global temperatures. In practice, algal biotechnology is the only form of BECCS that could be realized at scale without compromising food production. Current axenic algae cultivation systems lack robustness, are expensive and generally have marginal energy returns. Results Here it is shown that microbial communities sampled from alkaline soda lakes, grown as biofilms at high pH (up to 10) and high alkalinity (up to 0.5 kmol m−3 NaHCO3 and NaCO3) display excellent (>1.0 kg m−3 day−1) and robust (>80 days) biomass productivity, at low projected overall costs. The most productive biofilms contained >100 different species and were dominated by a cyanobacterium closely related to Phormidium kuetzingianum (>60%). Conclusion Frequent harvesting and red light were the key factors that governed the assembly of a stable and productive microbial community

Robust, high-productivity phototrophic carbon capture at high pH and alkalinity using natural microbial communities

Abstract Background Bioenergy with carbon capture and storage (BECCS) has come to be seen as one of the most viable technologies to provide the negative carbon dioxide emissions needed to constrain global temperatures. In practice, algal biotechnology is the only form of BECCS that could be realized at scale without compromising food production. Current axenic algae cultivation systems lack robustness, are expensive and generally have marginal energy returns. Results Here it is shown that microbial communities sampled from alkaline soda lakes, grown as biofilms at high pH (up to 10) and high alkalinity (up to 0.5 kmol m−3 NaHCO3 and NaCO3) display excellent (>1.0 kg m−3 day−1) and robust (>80 days) biomass productivity, at low projected overall costs. The most productive biofilms contained >100 different species and were dominated by a cyanobacterium closely related to Phormidium kuetzingianum (>60%). Conclusion Frequent harvesting and red light were the key factors that governed the assembly of a stable and productive microbial community

Biosignatures associated with freshwater microbialites

Freshwater microbialites (i.e., lithifying microbial mats) are quite rare in northern latitudes of the North American continent, with two lakes (Pavilion and Kelly Lakes) of southeastern BC containing a morphological variety of such structures. We investigated Kelly Lake microbialites using carbon isotope systematics, phospholipid fatty acids (PLFAs) and quantitative PCR to obtain biosignatures associated with microbial metabolism. δC values (mean δC -4.9 ± 1.1‱, = 8) were not in isotopic equilibrium with the atmosphere; however, they do indicate C-depleted inorganic carbon into Kelly Lake. The values of carbonates on microbialite surfaces (δC) fell within the range predicted for equilibrium precipitation from ambient lake water δC (-2.2 to -5.3‱). Deep microbialites (26 m) had an enriched δC value of -0.3 ± 0.5‱, which is a signature of photoautotrophy. The deeper microbialites (>20 m) had higher biomass estimates (via PLFAs), and a greater relative abundance of cyanobacteria (measured by 16S copies via qPCR). The majority of PLFAs constituted monounsaturated and saturated PLFAs, which is consistent with gram-negative bacteria, including cyanobacteria. The central PLFA δC values were highly depleted (-9.3 to -15.7‱) relative to δC values of bulk organic matter, suggesting a predominance of photoautotrophy. A heterotrophic signature was also detected via the depleted and 15:0 lipids (-3.2 to -5.2‱). Based on our carbonate isotopic biosignatures, PLFA, and qPCR measurements, photoautotrophy is enriched in the microbialites of Kelly Lake. This photoautotrophy enrichment is consistent with the microbialites of neighboring Pavilion Lake. This indication of photoautotrophy within Kelly Lake at its deepest depths raises new insights into the limits of measurable carbonate isotopic biosignatures under light and nutrient limitations