A new era for space life science: international standards for space omics processing

10 p.-2 fig.Space agencies have announced plans for human missions to the Moon to prepare for Mars. However, the space environment presents stressors that include radiation, microgravity, and isolation. Understanding how these factors affect biology is crucial for safe and effective crewed space exploration. There is a need to develop countermeasures, to adapt plants and microbes for nutrient sources and bioregenerative life support, and to limit pathogen infection. Scientists across the world are conducting space omics experiments on model organisms and, more recently, on humans. Optimal extraction of actionable scientific discoveries from these precious datasets will only occur at the collective level with improved standardization. To address this shortcoming, we established ISSOP (International Standards for Space Omics Processing), an international consortium of scientists who aim to enhance standard guidelines between space biologists at a global level. Here we introduce our consortium and share past lessons learned and future challenges related to spaceflight omics.European (D.B., H.C., N.J.S., R.H., and S. Giacomello) contribution is supported by ESA Topical Team “Space Omics: Towards an integrated ESA/NASA –omics database for spaceflight and ground facilities experiments” grant 4000131202/20/NL/PG/pt to R.H. S. Giacomello is supported by Formas grant 2017-01066_3. H.C. is supported by the Horizon Centre for Doctoral Training at the University of Nottingham (UKRI grant no. EP/S023305/1) and by the NASA GeneLab Animal Analysis Working Group. N.J.S. is supported by the National Aeronautics and Space Administration (NNX15AL16G). NASA GeneLab members (J.M.G., S.V.C., S.S.R., L.D., S. Gebre) are supported by the NASA Space Biology program within the NASA Science Mission Directorate's (SMD) Biological and Physical Sciences (BPS) Division. R.B. and S. Gilroy are supported by NASA (80NSSC19K0132). L.R. and M.M. represent the Omics Subgroup of Japan Society for the Promotion of Science (JSPS) KAKENHI funding group Living in Space and are supported by JP15K21745, JP15H05940, and JP20H03234. L.R. is supported by JSPS postdoctoral fellowship P20382. D.T. is supported by the Department of Biomedical and Health Informatics and The Children’s Hospital of Philadelphia Research Institute. K.F. is supported by the UC San Diego Department of Medicine and National Institutes of Health, grant UL1TR001442 of CTSA (Clinical and Translational Science Awards). C.E.M. is funded from the WorldQuant Foundation, The Pershing Square Sohn Cancer Research Alliance, and the National Institutes of Health (R01MH117406).Peer reviewe

Genome sequencing reveals diversification of virulence factor content and possible host adaptation in distinct subpopulations of Salmonella enterica

<p>Abstract</p> <p>Background</p> <p>Divergence of bacterial populations into distinct subpopulations is often the result of ecological isolation. While some studies have suggested the existence of <it>Salmonella enterica </it>subsp. <it>enterica </it>subclades, evidence for these subdivisions has been ambiguous. Here we used a comparative genomics approach to define the population structure of <it>Salmonella enterica </it>subsp. <it>enterica</it>, and identify clade-specific genes that may be the result of ecological specialization.</p> <p>Results</p> <p>Multi-locus sequence analysis (MLSA) and single nucleotide polymorphisms (SNPs) data for 16 newly sequenced and 30 publicly available genomes showed an unambiguous subdivision of <it>S. enterica </it>subsp. <it>enterica </it>into at least two subpopulations, which we refer to as clade A and clade B. Clade B strains contain several clade-specific genes or operons, including a β-glucuronidase operon, a S-fimbrial operon, and cell surface related genes, which strongly suggests niche specialization of this subpopulation. An additional set of 123 isolates was assigned to clades A and B by using qPCR assays targeting subpopulation-specific SNPs and genes of interest. Among 98 serovars examined, approximately 20% belonged to clade B. All clade B isolates contained two pathogenicity related genomic islands, SPI-18 and a cytolethal distending toxin islet; a combination of these two islands was previously thought to be exclusive to serovars Typhi and Paratyphi A. Presence of β-glucuronidase in clade B isolates specifically suggests an adaptation of this clade to the vertebrate gastrointestinal environment.</p> <p>Conclusions</p> <p><it>S. enterica </it>subsp. <it>enterica </it>consists of at least two subpopulations that differ specifically in genes involved in host and tissue tropism, utilization of host specific carbon and nitrogen sources and are therefore likely to differ in ecology and transmission characteristics.</p

Comparative genomics of the bacterial genus Listeria: Genome evolution is characterized by limited gene acquisition and limited gene loss

<p>Abstract</p> <p>Background</p> <p>The bacterial genus <it>Listeria </it>contains pathogenic and non-pathogenic species, including the pathogens <it>L. monocytogenes </it>and <it>L. ivanovii</it>, both of which carry homologous virulence gene clusters such as the <it>prfA </it>cluster and clusters of internalin genes. Initial evidence for multiple deletions of the <it>prfA </it>cluster during the evolution of <it>Listeria </it>indicates that this genus provides an interesting model for studying the evolution of virulence and also presents practical challenges with regard to definition of pathogenic strains.</p> <p>Results</p> <p>To better understand genome evolution and evolution of virulence characteristics in <it>Listeria</it>, we used a next generation sequencing approach to generate draft genomes for seven strains representing <it>Listeria </it>species or clades for which genome sequences were not available. Comparative analyses of these draft genomes and six publicly available genomes, which together represent the main <it>Listeria </it>species, showed evidence for (i) a pangenome with 2,032 core and 2,918 accessory genes identified to date, (ii) a critical role of gene loss events in transition of <it>Listeria </it>species from facultative pathogen to saprotroph, even though a consistent pattern of gene loss seemed to be absent, and a number of isolates representing non-pathogenic species still carried some virulence associated genes, and (iii) divergence of modern pathogenic and non-pathogenic <it>Listeria </it>species and strains, most likely circa 47 million years ago, from a pathogenic common ancestor that contained key virulence genes.</p> <p>Conclusions</p> <p>Genome evolution in <it>Listeria </it>involved limited gene loss and acquisition as supported by (i) a relatively high coverage of the predicted pan-genome by the observed pan-genome, (ii) conserved genome size (between 2.8 and 3.2 Mb), and (iii) a highly syntenic genome. Limited gene loss in <it>Listeria </it>did include loss of virulence associated genes, likely associated with multiple transitions to a saprotrophic lifestyle. The genus <it>Listeria </it>thus provides an example of a group of bacteria that appears to evolve through a loss of virulence rather than acquisition of virulence characteristics. While <it>Listeria </it>includes a number of species-like clades, many of these putative species include clades or strains with atypical virulence associated characteristics. This information will allow for the development of genetic and genomic criteria for pathogenic strains, including development of assays that specifically detect pathogenic <it>Listeria </it>strains.</p

IONIZATION ENERGIES OF THE ISOMERS OF CN2CN_{2}

Author Institution: Cherry L. Emerson Center for Scientific Computation, Santa Clara University; Department of Chemistry, Santa Clara UniversityThe geometries and harmonic vibrational frequencies for the structural isomers of $CN_{2}$ and the corresponding cations have been calculated at the $B3LYP/6-311+g(2df)$ level. Adiabatic ionization energies were calculated at the G1, G2(MP2) and G2 levels as well for each of the isomers. Of the cations, the linear molecule $CNN^{+}$ is found to have the lowest energy. $NCN^{+}$ (also linear) lies 0.2 eV higher in energy than $CNN^{+}$. The other isomer of the cation, cyc-$CN_{2}^{+}$, has a cyclic structure with $C_{2v}$ symmetry and lies 0.8 eV higher in energy than $CNN^{+}$. The adiabatic ionization energies of the radicals determined at the G2 level are $IP(NCN) = 12.52 \pm 0.07 eV$, $IP(CNN) = 11.01 \pm 0.07 eV$ and $IP(cyc-CN_{2}) = 11.94 \pm 0.07 eV$

A Whole-Genome Single Nucleotide Polymorphism-Based Approach To Trace and Identify Outbreaks Linked to a Common Salmonella enterica subsp. enterica Serovar Montevideo Pulsed-Field Gel Electrophoresis Type

In this study, we report a whole-genome single nucleotide polymorphism (SNP)-based evolutionary approach to study the epidemiology of a multistate outbreak of Salmonella enterica subsp. enterica serovar Montevideo. This outbreak included 272 cases that occurred in 44 states between July 2009 and April 2010. A case-control study linked the consumption of salami made with contaminated black and red pepper to the outbreak. We sequenced, on the SOLiD System, 47 isolates with XbaI PFGE pattern JIXX01.0011, a common pulsed-field gel electrophoresis (PFGE) pattern associated with isolates from the outbreak. These isolates represented 20 isolates collected from human sources during the period of the outbreak and 27 control isolates collected from human, food, animal, and environmental sources before the outbreak. Based on 253 high-confidence SNPs, we were able to reconstruct a tip-dated molecular clock phylogeny of the isolates and to assign four human isolates to the actual outbreak. We developed an SNP typing assay to rapidly discriminate between outbreak-related cases and non-outbreak-related cases and tested this assay on an extended panel of 112 isolates. These results suggest that only a very small percentage of the human isolates with the outbreak PFGE pattern and obtained during the outbreak period could be attributed to the actual pepper-related outbreak (20%), while the majority (80%) of the putative cases represented background cases. This study demonstrates that next-generation-based SNP typing provides the resolution and accuracy needed for outbreak investigations of food-borne pathogens that cannot be distinguished by currently used subtyping methods

Identification and Characterization of Novel <em>Salmonella</em> Mobile Elements Involved in the Dissemination of Genes Linked to Virulence and Transmission

<div><p>The genetic diversity represented by >2,500 different <em>Salmonella</em> serovars provides a yet largely uncharacterized reservoir of mobile elements that can contribute to the frequent emergence of new pathogenic strains of this important zoonotic pathogen. Currently, our understanding of <em>Salmonella</em> mobile elements is skewed by the fact that most studies have focused on highly virulent or common serovars. To gain a more global picture of mobile elements in <em>Salmonella</em>, we used prediction algorithms to screen for mobile elements in 16 sequenced <em>Salmonella</em> genomes representing serovars for which no prior genome scale mobile element data were available. From these results, selected mobile elements underwent further analyses in the form of validation studies, comparative analyses, and PCR-based population screens. Through this analysis we identified a novel plasmid that has two cointegrated replicons (IncI1-IncFIB); this plasmid type was found in four genomes representing different <em>Salmonella</em> serovars and contained a virulence gene array that had not been previously identified. A <em>Salmonella</em> Montevideo isolate contained an IncHI and an IncN2 plasmid, which both encoded antimicrobial resistance genes. We also identified two novel genomic islands (SGI2 and SGI3), and 42 prophages with mosaic architecture, seven of them harboring known virulence genes. Finally, we identified a novel integrative conjugative element (ICE) encoding a type IVb pilus operon in three non-typhoidal <em>Salmonella</em> serovars. Our analyses not only identified a considerable number of mobile elements that have not been previously reported in <em>Salmonella</em>, but also found evidence that these elements facilitate transfer of genes that were previously thought to be limited in their distribution among <em>Salmonella</em> serovars. The abundance of mobile elements encoding pathogenic properties may facilitate the emergence of strains with novel combinations of pathogenic traits.</p> </div

Phylogeny inferred with maximum likelihood of the IncI1 replicon.

<p>Maximum likelihood phylogeny conducted with IncI1 sequences for plasmids found in this study and currently available sequences. Analysis was conducted with RAxML. Two clades were observed (clade I and clade II), with clade I containing the <i>Salmonella</i> plasmids analyzed here.</p