A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum

A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse 1a. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community

Meta-analysis of 49 549 individuals imputed with the 1000 Genomes Project reveals an exonic damaging variant in ANGPTL4 determining fasting TG levels

Background So far, more than 170 loci have been associated with circulating lipid levels through genomewide association studies (GWAS). These associations are largely driven by common variants, their function is often not known, and many are likely to be markers for the causal variants. In this study we aimed to identify more new rare and low-frequency functional variants associated with circulating lipid levels. Methods We used the 1000 Genomes Project as a reference panel for the imputations of GWAS data from ~60 000 individuals in the discovery stage and ~90 000 samples in the replication stage. Results Our study resu

Genetic Sharing with Cardiovascular Disease Risk Factors and Diabetes Reveals Novel Bone Mineral Density Loci.

Bone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR) method to identify single nucleotide polymorphisms (SNPs) associated with BMD by leveraging cardiovascular disease (CVD) associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD) at conditional FDR < 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity

Seasonal dynamics of the accumulation, distribution and redistribution of dry matter and mineral nutrients in a weedy species of gladiolus (gladiolus caryophyllaceus)

The seasonal dynamics of the accumulation, distribution and redistribution of dry matter and 12 mineral nutrients by a weedy species of gladiolus (Gladiolus caryophyllaceus) were studied at Perth, Western Australia, where it has colonized the nutrient-poor sandy soils. Parent corms sprouted in autumn, and the plants had completed their growth cycle by early summer. The mature replacement corm had 3 5-25% of the plant’s P, Ca, Na, Zn and Cu, 5-15% of its K, N, Cl, Mg, S and dry matter, and < 5% of its Fe and Mn. Seeds had 26% of the plant’s dry matter, 60% of its N and P, 21-33% of its S, Mg, Cu and K, 5-20% of its Fe, Mn and Zn, and < 5% of its Ca and Na. The mature vegetative shoot had 47% of the plant’s dry matter and over 40% of each nutrient, except for N, P and Cu. Phosphorus, K and N were redistributed from the parent corm with over 85% efficiency, S, Mg, Zn and Cu with 60-70% efficiency, but there was < 10% redistribution of Ca, Na, Cl, Fe and Mn. The efficiency of redistribution from the leafy shoot was over 70% for N and P, 29-52% for K, Mg and Cu, 16-20% for S, Zn and Cl, but negligible for Ca, Na, Fe and Mn. Redistribution from the shoot could have provided the replacement corm and seeds with 53-98% of their Cu, Mg, N, P and K, and 29-38% of their S, Zn and dry matter. Seeds contained over 60% of each nutrient in a capsule, except for Ca, Na and Fe. Redistribution from the capsule walls could have provided 13-19% of the P, Cu and Zn, and 3-7% of the N, K, Mg and dry matter accumulated by seeds. Each plant produced an average of 520 seeds. Removal of flowers and buds at first anthesis resulted in a larger replacement corm containing a greater quantity of most nutrients, indicating competition between the replacement corm and seeds for nutrients. Redistribution from parent to replacement cormlets in the absence of shoot and root development was high, with over 50% of the dry matter and each nutrient, except for Ca, being transferred. Concentrations of nutrients were low in all organs of G. caryophyllaceus, especially the replacement corm. It was concluded that the effective redistribution of key nutrients, such as N and P, to reproductive structures and tolerance of low internal concentrations of nutrients contribute to the capacity of G. caryophyllaceus to colonize and persist on infertile soils