Resolving the complete genome of Kuenenia stuttgartiensis from a membrane bioreactor enrichment using Single-Molecule Real-Time sequencing

Contains fulltext : 190074.pdf (publisher's version ) (Open Access)10 p

The identification of informative genes from multiple datasets with increasing complexity

Background In microarray data analysis, factors such as data quality, biological variation, and the increasingly multi-layered nature of more complex biological systems complicates the modelling of regulatory networks that can represent and capture the interactions among genes. We believe that the use of multiple datasets derived from related biological systems leads to more robust models. Therefore, we developed a novel framework for modelling regulatory networks that involves training and evaluation on independent datasets. Our approach includes the following steps: (1) ordering the datasets based on their level of noise and informativeness; (2) selection of a Bayesian classifier with an appropriate level of complexity by evaluation of predictive performance on independent data sets; (3) comparing the different gene selections and the influence of increasing the model complexity; (4) functional analysis of the informative genes. Results In this paper, we identify the most appropriate model complexity using cross-validation and independent test set validation for predicting gene expression in three published datasets related to myogenesis and muscle differentiation. Furthermore, we demonstrate that models trained on simpler datasets can be used to identify interactions among genes and select the most informative. We also show that these models can explain the myogenesis-related genes (genes of interest) significantly better than others (P < 0.004) since the improvement in their rankings is much more pronounced. Finally, after further evaluating our results on synthetic datasets, we show that our approach outperforms a concordance method by Lai et al. in identifying informative genes from multiple datasets with increasing complexity whilst additionally modelling the interaction between genes. Conclusions We show that Bayesian networks derived from simpler controlled systems have better performance than those trained on datasets from more complex biological systems. Further, we present that highly predictive and consistent genes, from the pool of differentially expressed genes, across independent datasets are more likely to be fundamentally involved in the biological process under study. We conclude that networks trained on simpler controlled systems, such as in vitro experiments, can be used to model and capture interactions among genes in more complex datasets, such as in vivo experiments, where these interactions would otherwise be concealed by a multitude of other ongoing events

Mapping 123 million neonatal, infant and child deaths between 2000 and 2017

Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2—to end preventable child deaths by 2030—we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000–2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations

Resolving the complete genome of Kuenenia stuttgartiensis from a membrane bioreactor enrichment using Single-Molecule Real-Time sequencing

Contains fulltext : 190074.pdf (publisher's version ) (Open Access)10 p

Gene Family Evolution Reflects Adaptation to Soil Environmental Stressors in the Genome of the Collembolan Orchesella cincta

Collembola (springtails) are detritivorous hexapods that inhabit the soil and its litter layer. The ecology of the springtail Orchesella cincta is extensively studied in the context of adaptation to anthropogenically disturbed areas. Here, we present a draft genome of an O. cincta reference strain with an estimated size of 286.8 Mbp, containing 20,249 genes. In total, 446 gene families are expanded and 1,169 gene families evolved specific to this lineage. Besides these gene families involved in general biological processes, we observe gene clusters participating in xenobiotic biotransformation. Furthermore, we identified 253 cases of horizontal gene transfer (HGT). Although the largest percentage of them originated from bacteria (37.5%), we observe an unusually high percentage (30.4%) of such genes of fungal origin. The majority of foreign genes are involved in carbohydrate metabolism and cellulose degradation. Moreover, some foreign genes (e.g., bacillopeptidases) expanded after HGT. We hypothesize that horizontally transferred genes could be advantageous for food processing in a soil environment that is full of decaying organic material. Finally, we identified several lineage-specific genes, expanded gene families, and horizontally transferred genes, associated with altered gene expression as a consequence of genetic adaptation to metal stress. This suggests that these genome features may be preadaptations allowing natural selection to act on. In conclusion, this genome study provides a solid foundation for further analysis of evolutionary mechanisms of adaptation to environmental stressors

Poly(A) binding protein nuclear 1 levels affect alternative polyadenylation

The choice for a polyadenylation site determines the length of the 3′-untranslated region (3′-UTRs) of an mRNA. Inclusion or exclusion of regulatory sequences in the 3′-UTR may ultimately affect gene expression levels. Poly(A) binding protein nuclear 1 (PABPN1) is involved in polyadenylation of pre-mRNAs. An alanine repeat expansion in PABPN1 (exp-PABPN1) causes oculopharyngeal muscular dystrophy (OPMD). We hypothesized that previously observed disturbed gene expression patterns in OPMD muscles may have been the result of an effect of PABPN1 on alternative polyadenylation, influencing mRNA stability, localization and translation. A single molecule polyadenylation site sequencing method was developed to explore polyadenylation site usage on a genome-wide level in mice overexpressing exp-PABPN1. We identified 2012 transcripts with altered polyadenylation site usage. In the far majority, more proximal alternative polyadenylation sites were used, resulting in shorter 3′-UTRs. 3′-UTR shortening was generally associated with increased expression. Similar changes in polyadenylation site usage were observed after knockdown or overexpression of expanded but not wild-type PABPN1 in cultured myogenic cells. Our data indicate that PABPN1 is important for polyadenylation site selection and that reduced availability of functional PABPN1 in OPMD muscles results in use of alternative polyadenylation sites, leading to large-scale deregulation of gene expression

Aging as Accelerated Accumulation of Somatic Variants: Whole-Genome Sequencing of Centenarian and Middle-Aged Monozygotic Twin Pairs

It has been postulated that aging is the consequence of an accelerated accumulation of somatic DNA mutations and that subsequent errors in the primary structure of proteins ultimately reach levels sufficient to affect organismal functions. The technical limitations of detecting somatic changes and the lack of insight about the minimum level of erroneous proteins to cause an error catastrophe hampered any firm conclusions on these theories. In this study, we sequenced the whole genome of DNA in whole blood of two pairs of monozygotic (MZ) twins, 40 and 100 years old, by two independent next-generation sequencing (NGS) platforms (Illumina and Complete Genomics). Potentially discordant single-base substitutions supported by both platforms were validated extensively by Sanger, Roche 454, and Ion Torrent sequencing. We demonstrate that the genomes of the two twin pairs are germ-line identical between co-twins, and that the genomes of the 100-year-old MZ twins are discerned by eight confirmed somatic single-base substitutions, five of which are within introns. Putative somatic variation between the 40-year-old twins was not confirmed in the validation phase. We conclude from this systematic effort that by using two independent NGS platforms, somatic single nucleotide substitutions can be detected, and that a century of life did not result in a large number of detectable somatic mutations in blood. The low number of somatic variants observed by using two NGS platforms might provide a framework for detecting disease-related somatic variants in phenotypically discordant MZ twins. © The Authors 2013

Reproducibility of high-throughput mRNA and small RNA sequencing across laboratories

RNA sequencing is an increasingly popular technology for genome-wide analysis of transcript sequence and abundance. However, understanding of the sources of technical and interlaboratory variation is still limited. To address this, the GEUVADIS consortium sequenced mRNAs and small RNAs of lymphoblastoid cell lines of 465 individuals in seven sequencing centers, with a large number of replicates. The variation between laboratories appeared to be considerably smaller than the already limited biological variation. Laboratory effects were mainly seen in differences in insert size and GC content and could be adequately corrected for. In small-RNA sequencing, the microRNA (miRNA) content differed widely between samples owing to competitive sequencing of rRNA fragments. This did not affect relative quantification of miRNAs. We conclude that distributing RNA sequencing among different laboratories is feasible, given proper standardization and randomization procedures. We provide a set of quality measures and guidelines for assessing technical biases in RNA-seq data