Project description:Investigation of mRNA expression (using HiSeq 2500) in response to treatment of Daphnia magna to pyriproxyfen, wetland water, or stormwater samples.
Project description:To unravel complex dynamics of environmental disturbance and microbial metabolic activities, we set up laboratory microcosms to investigate the effects of SO42- and O2 alone or in combination on microbial activities and interactions, as well as the resulting fate of carbon within wetland soil. We used proteogenomics to characterize the biochemical and physiological responses of microbial communities to individual perturbations and their combined effects. Stoichiometric models were employed to deconvolute carbon exchanges among the main functional guilds. These findings can contribute to the development of mechanistic models for predicting greenhouse gas emissions from wetland ecosystems under various climate change scenarios.
Project description:In recent years, sediments from cave environments have provided invaluable insights into ancient hominids, as well as past fauna and flora. Unfortunately, locations with favourable conditions for ancient DNA (aDNA) preservation in sediments are scarce. In this study we analysed a set of samples obtained from sediments adhered to different human skeletal elements, originating from Neolithic to Medieval sites in England, and performed metagenomics and metaproteomics analysis. From them, we were able to reconstruct a partial human genome. The genetic profile of those human sequences matches the one recovered from the original skeletal element. Additionally, aDNA sequences matching the genomes of endogenous gut and oral microbiome bacteria were identified. We also found the presence of genetic sequences corresponding to animals and plants. In particular we managed to retrieve the partial genome and proteome of a Black Rat (Rattus rattus), sharing close genetic affinities to other medieval Rattus rattus. Our results demonstrate that material usually discarded, as it is sediments adhering to human remains, can be used to get a glimpse of the environmental conditions at the time of the death of an individual.
Project description:The abundance of bacterial (AOB) and archaeal (AOA) ammonia oxidisers, assessed using quantitative PCR measurements of their respective a-subunit of the ammonia monooxygenase (amoA) genes, and ammonia oxidation rates were measured in four contrasting coastal sediments in the Western English Channel. Sediment was sampled bimonthly from July 2008 to May 2011, and measurements of ammonia oxidiser abundance and activity compared to a range of environmental variables including salinity, temperature, water column nutrients and sediment carbon and nitrogen content. Despite a higher abundance of AOA amoA genes within all sediments, and at all time-points, rates of ammonia oxidation correlated with AOB and not AOA amoA gene abundance. Other than ammonia oxidation rate, sediment particle size was the only variable that correlated with the spatial and temporal patterns of AOB amoA gene abundance, implying a preference of the AOB for larger sediment particles. This is possibly due to deeper oxygen penetration into the sandier sediments, increasing the area available for ammonia oxidation to occur, higher concentrations of inhibitory sulphide with pore waters of muddier sediments or a combination of both oxygen and sulphide concentrations. Similar to many other temporal studies of nitrification within estuarine and coastal sediments, decreases in AOB amoA gene abundance were evident during summer and autumn, with maximum abundance and ammonia oxidation rates occurring in winter and early spring. The lack of correlation between AOA amoA gene abundance and ammonium oxidation rate suggests an alternative role for amoA-carrying AOA within these sediments.