Ontogenetic trace element distribution in brachiopod shells: an indicator of original seawater chemistry

Articulated fossil brachiopod shells have been used extensively to extract primary chemical information of Phanerozoic seawater. Despite the selection of well-preserved shells using trace element, microstructure and cathodoluminescence criteria, there are still concerns as to whether the selected brachiopod shells do indeed contain original seawater signals. Analyzed in-situ by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LAICPMS), Sr, Na, Mg, Mn, B and Ba distribute symmetrically in shell transects of the modem brachiopods Magellania flavescens and Terebratulina septentrionalis. Symmetry of the trace element distribution pattern is considered an intrinsic and original ontogenetic property of the brachiopod shell chemistry. The trace element distribution is symmetrical in a well-preserved shell of the Devonian brachiopod Independatrypa lemma, indicating that the selected shell by the conventional criteria has preserved its original seawater signal for 400 Ma. In another specimen of I. lemma that is considered diagenetically altered, trace element concentrations are asymmetrically distributed in the shell. The agreement between the distribution criteria and the conventional methods indicates the latter can be used to select brachiopod shells with original seawater chemistry. The average element concentration in the whole shell of unaltered brachiopods should be a reflection of the seawater chemistry, while its change in different part of a shell reflects ontogenetic effect, and its high frequent fluctuations in a transect are results of changes in environmental parameters with seasonal or annual characteristics. (C) 2004 Elsevier B.V. All rights reserved

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Ontogenetic trace element distribution in brachiopod shells: an indicator of original seawater chemistry

Articulated fossil brachiopod shells have been used extensively to extract primary chemical information of Phanerozoic seawater. Despite the selection of well-preserved shells using trace element, microstructure and cathodoluminescence criteria, there are still concerns as to whether the selected brachiopod shells do indeed contain original seawater signals. Analyzed in-situ by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LAICPMS), Sr, Na, Mg, Mn, B and Ba distribute symmetrically in shell transects of the modem brachiopods Magellania flavescens and Terebratulina septentrionalis. Symmetry of the trace element distribution pattern is considered an intrinsic and original ontogenetic property of the brachiopod shell chemistry. The trace element distribution is symmetrical in a well-preserved shell of the Devonian brachiopod Independatrypa lemma, indicating that the selected shell by the conventional criteria has preserved its original seawater signal for 400 Ma. In another specimen of I. lemma that is considered diagenetically altered, trace element concentrations are asymmetrically distributed in the shell. The agreement between the distribution criteria and the conventional methods indicates the latter can be used to select brachiopod shells with original seawater chemistry. The average element concentration in the whole shell of unaltered brachiopods should be a reflection of the seawater chemistry, while its change in different part of a shell reflects ontogenetic effect, and its high frequent fluctuations in a transect are results of changes in environmental parameters with seasonal or annual characteristics. (C) 2004 Elsevier B.V. All rights reserved