Proteins persist longer in the fossil record than DNA, but the longevity, survival mechanisms and substrates remain contested. Here, we demonstrate the role of mineral binding in preserving the protein sequence in ostrich (Struthionidae) eggshell, including from the palaeontological sites of Laetoli (3.8 Ma) and Olduvai Gorge (1.3 Ma) in Tanzania. By tracking protein diagenesis back in time we find consistent patterns of preservation, demonstrating authenticity of the surviving sequences. Molecular dynamics simulations of struthiocalcin-1 and -2, the dominant proteins within the eggshell, reveal that distinct domains bind to the mineral surface. It is the domain with the strongest calculated binding energy to the calcite surface that is selectively preserved. Thermal age calculations demonstrate that the Laetoli and Olduvai peptides are 50 times older than any previously authenticated sequence (equivalent to ~16 Ma at a constant 10°C).DOI: http://dx.doi.org/10.7554/eLife.17092.001

The abundance of volatile organic compounds (VOCs) found in homes depends on many factors such as emissions, ventilation and the oxidative environment and these are evolving over time, reflecting changes in chemical use, behaviour and building design/materials. The concentrations of VOCs in 25 UK homes of varying ages, design and occupancy were quantified using continuous indoor air sampling over five days. Air was collected through low flow (1 mL min) constant flow restrictors into evacuated 6 L internally silica-treated canisters until the canisters reached atmospheric pressure. This was followed by thermal desorption-gas chromatography and high mass accuracy time-of-flight mass spectrometry (TD-GC-TOF/MS). A fully quantitative analysis was performed on the eight most abundant hydrocarbon-based VOCs found. Despite differences in building characteristics and occupant numbers 94% of the homes had d-limonene or α-pinene as the most abundant VOCs. The variability seen across the 25 homes in concentrations of monoterpenes indoors was considerably greater than that of species such as isoprene, benzene, toluene and xylenes. The variance in VOCs indoors appeared to be strongly influenced by occupant activities such as cleaning with 5-day average concentrations of d-limonene ranging from 18 μg m to over 1400 μg m, a peak domestic value that is possibly the highest yet reported in the literature.

Field measurements of volatile organic compounds (VOCs) are important in a range of disciplines including air pollution science, medical diagnostics and security screening. There is an enduring need for a portable device that provides reliable compoundspecific measurements, at mixing ratios in the part per billion and part per trillion range. Outdoor VOCs sources are primarily from traffic, and the information provided from such measurements could inform the public of the sources of emission and potentially affect their decisions and behaviour. Similarly, measurements of VOCs in indoor environments could increase awareness of emissions from building materials or the use of various consumer products and provide information on indoor ventilation. This work describes the development of a lab-on-a-chip (LOC) device for VOC measurements, a collaboration of multiple disciplines, involving research and development from a number of different fields in sciences and engineering. The objective is to develop a multispecies sensor for measuring VOCs in gas phase samples, through the deployment of thermal desorption methods in combination with a micro-fabricated gas chromatography -photoionization detection (GC-PID) device. Most of the work has been done in the evaluation of the PID detection means, which has shown to offer substantial potential for the development of a field portable air quality sensor. Initial tests on a Peltier device to control the temperature of a GC column have also been carried out. The use of such device removes the dependence on the bulky GC oven which has high power consumption, and allows the initial temperature of the column to be as low as 10 o C, potentially enabling the analysis of VOCs without the need for cryogenic cooling. The final developed system will be validated using controlled experiments and against reference standards and measurement techniques, and applied in number of real-world monitoring investigations, including indoor atmospheres and air pollution studies.

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