Surface sediment diatom assemblages and water quality in Welsh lakes: brief descriptions of 33 sites selected for study

In May 1987 surface sediment and periphyton samples were collected for diatom analysis from 27 upland lakes in mid- and north Wales (Figure 1). The sites were selected to provide a range of water acidities from circumneutral to strongly acid. The results, together with those collected from other regions in the British Isles, are to be used to produce a UK diatom-water quality data set that will facilitate calibration of sediment core diatom assemblages and reconstruction of past water quality characteristics such as pH (eg. Birks et al. 1990)

Lake Acidification in the United Kingdom II. A preliminary report to the Department of the Environment under Contract PECD 7/10/167

This report summarises progress made in Department of the Environment project PECD 7/10/167 - "causes and extent of lake acidification in the United Kingdom". It includes data and results available at the present time and indicates where work is still in progress. We expect that all work will be completed on schedule and that a final report will be issued shortly after completion of the contract (March 31st 1990)

The Surface Waters Acidification Project Palaeolimnology Programme: modern diatom/lake-water chemistry data-set

In 1983, when the Surface Waters Acidification Programme (SWAP) was announced, we were asked to design and implement a palaeolimnology sub-project involving scientists from Sweden, Norway, and the UK. Our aim was to reconstruct the acidification history of a range of sites in the three countries and to identify and evaluate the various alternative causes of lake acidification. The results of the project have been published recently (Battarbee et al. 1990, Renberg and Battarbee 1990). Although a comprehensive range of palaeolimnological methods and approaches was used in the study we recognised diatom analysis as central to the entire project. We consequently committed considerable effort to improving our diatom methodology and we were especially concerned with the pursuit of a common approach to diatom taxonomy and pH reconstruction. This effort centred on the creation and analysis of a large data-set of surface-sediment diatom assemblages and associated environmental variables from 170 sites representing the full range of lake types in the acid-sensitive and acidified regions of the three countries

A Bayesian palaeoenvironmental transfer function model for acidified lakes

A Bayesian approach to palaeoecological environmental reconstruction deriving from the unimodal responses generally exhibited by organisms to an environmental gradient is described. The approach uses Bayesian model selection to calculate a collection of probability-weighted, species-specific response curves (SRCs) for each taxon within a training set, with an explicit treatment for zero abundances. These SRCs are used to reconstruct the environmental variable from sub-fossilised assemblages. The approach enables a substantial increase in computational efficiency (several orders of magnitude) over existing Bayesian methodologies. The model is developed from the Surface Water Acidification Programme (SWAP) training set and is demonstrated to exhibit comparable predictive power to existing Weighted Averaging and Maximum Likelihood methodologies, though with improvements in bias; the additional explanatory power of the Bayesian approach lies in an explicit calculation of uncertainty for each individual reconstruction. The model is applied to reconstruct the Holocene acidification history of the Round Loch of Glenhead, including a reconstruction of recent recovery derived from sediment trap data.The Bayesian reconstructions display similar trends to conventional (Weighted Averaging Partial Least Squares) reconstructions but provide a better reconstruction of extreme pH and are more sensitive to small changes in diatom assemblages. The validity of the posteriors as an apparently meaningful representation of assemblage-specific uncertainty and the high computational efficiency of the approach open up the possibility of highly constrained multiproxy reconstructions

Metabolic shift underlies recovery in reversible infantile respiratory chain deficiency.

Reversible infantile respiratory chain deficiency (RIRCD) is a rare mitochondrial myopathy leading to severe metabolic disturbances in infants, which recover spontaneously after 6-months of age. RIRCD is associated with the homoplasmic m.14674T>C mitochondrial DNA mutation; however, only ~ 1/100 carriers develop the disease. We studied 27 affected and 15 unaffected individuals from 19 families and found additional heterozygous mutations in nuclear genes interacting with mt-tRNAGlu including EARS2 and TRMU in the majority of affected individuals, but not in healthy carriers of m.14674T>C, supporting a digenic inheritance. Our transcriptomic and proteomic analysis of patient muscle suggests a stepwise mechanism where first, the integrated stress response associated with increased FGF21 and GDF15 expression enhances the metabolism modulated by serine biosynthesis, one carbon metabolism, TCA lipid oxidation and amino acid availability, while in the second step mTOR activation leads to increased mitochondrial biogenesis. Our data suggest that the spontaneous recovery in infants with digenic mutations may be modulated by the above described changes. Similar mechanisms may explain the variable penetrance and tissue specificity of other mtDNA mutations and highlight the potential role of amino acids in improving mitochondrial disease

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms