The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.

SPAdes, a new genome assembly algorithm and its applications to single-cell sequencing ( 7th Annual SFAF Meeting, 2012)

The genus Fritillaria comprises approximately 130 perennial herbaceous species. In the Pharmacopoeia of the People’s Republic of China, the bulbs of 11 Fritillaria species are used in Chinese herbal medicines. However, the traditional methods of morphological classification cannot accurately identify closely related species of Fritillaria. Previous studies have attempted to identify these species with universal molecular markers, but insufficient phylogenetic signal was available. In this study, the complete chloroplast genomes of eight Fritillaria species were compared. The length of the eight Fritillaria chloroplast genomes ranges from 151,009 bp to 152,224 bp. A total of 136 SSR loci were identified, including 124 polymorphic SSR loci. For large repeat sequences, 108 repeat loci and four types of repeats were observed. Ten highly variable regions were identified as potential molecular markers. These SSRs, large repeat sequences and highly variable regions provide important information for the development of genetic markers and DNA fingerprints. Phylogenetic analyses showed that the topological structures of all data sets (except the IR regions) were in complete agreement and well resolved. Overall, this study provides comprehensive chloroplast genomic resources, which will be valuable for future studies of evolution and species identification in Fritillaria.

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Chloroplast genomic resources for phylogeny and DNA barcoding: a case study on Fritillaria.

Because the role of Chinese courts is limited, in general, to procedural matters, it is the tax administration that determines whether a transaction involves tax avoidance. This organ of the government places special emphasis on international tax avoidance arrangements. In particular, it has been concerned about the inappropriate use by multinational enterprises of double taxation treaties with third parties offering low tax rates on Chinese source income. This practice provided the impetus for enactment of a GAAR as part of reform of the Corporate Income Tax Law, effective in 2008. The GAAR provides authority to investigate certain anti-avoidance activities and authorizes the tax administration to employ a substance over form approach by reference to five factors. These factors permit the tax administration to consider the form and substance of an arrangement, timing, reference to steps taken to put the arrangement into place, financial effects, and tax consequences. If tax avoidance is uncovered, the tax administration is given authority to re-characterize the transaction according to economic reality. The adoption of a GAAR has had considerable impact on the activities of multinationals that may use conduit Chinese companies for investment only if there is economic substance to the arrangement.

The People’s Republic of China

Lilium is a large genus that includes approximately 110 species distributed throughout cold and temperate regions of the Northern Hemisphere. The species-level phylogeny of Lilium remains unclear; previous studies have found universal markers but insufficient phylogenetic signals. In this study, we present the use of complete chloroplast genomes to explore the phylogeny of this genus. We sequenced nine Lilium chloroplast genomes and retrieved seven published chloroplast genomes for comparative and phylogenetic analyses. The genomes ranged from 151,655 bp to 153,235 bp in length and had a typical quadripartite structure with a conserved genome arrangement and moderate divergence. A comparison of sixteen Lilium chloroplast genomes revealed ten mutation hotspots. Single nucleotide polymorphisms (SNPs) for any two Lilium chloroplast genomes ranged from 8 to 1,178 and provided robust data for phylogeny. Except for some of the shortest internodes, phylogenetic relationships of the Lilium species inferred from the chloroplast genome obtained high support, indicating that chloroplast genome data will be useful to help resolve the deeper branches of phylogeny.

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Complete chloroplast genome sequences of Lilium : insights into evolutionary dynamics and phylogenetic analyses

Lythraceae belongs to the order Myrtales, which is part of Archichlamydeae. The family has 31 genera containing approximately 620 species of herbs, shrubs and trees. Of these 31 genera, five large genera each possess 35 or more species. They are Lythrum, with 35; Rotala, with 45; Nesaea, with 50; Lagerstroemia, with 56; and Cuphea, with 275 species. We reported six newly sequenced chloroplast (cp) genomes (Duabanga grandiflora, Trapa natans, Lythrum salicaria, Lawsonia inermis, Woodfordia fruticosa and Rotala rotundifolia) and compared them with 16 other cp genomes of Lythraceae species. The cp genomes of the 22 Lythraceae species ranged in length from 152,049 bp to 160,769 bp. In each Lythraceae species, the cp genome contained 112 genes consisting of 78 protein coding genes, four ribosomal RNAs and 30 transfer RNAs. Furthermore, we detected 211–332 simple sequence repeats (SSRs) in six categories and 7–27 long repeats in four categories. We selected ten divergent hotspots (ndhF, matK, ycf1, rpl22, rpl32, trnK-rps16, trnR-atpA, rpl32-trnL, trnH-psbA and trnG-trnR) among the 22 Lythraceae species to be potential molecular markers. We constructed phylogenetic trees from 42 Myrtales plants with 8 Geraniales plants as out groups. The relationships among the Myrtales species were effectively distinguished by maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (BI) trees constructed using 66 protein coding genes. Generally, the 22 Lythraceae species gathered into one clade, which was resolved as sister to the three Onagraceae species. Compared with Melastomataceae and Myrtaceae, Lythraceae and Onagraceae differentiated later within Myrtales. The study provided ten potential molecular markers as candidate DNA barcodes and contributed cp genome resources within Myrtales for further study.

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Comparative analyses of chloroplast genomes from 22 Lythraceae species: inferences for phylogenetic relationships and genome evolution within Myrtales

Genome size (GS) diversity is of fundamental biological importance. The occurrence of giant genomes in angiosperms is restricted to just a few lineages in the analyzed genome size of plant species so far. It is still an open question whether GS diversity is shaped by neutral or natural selection. The genus Lilium, with giant genomes, is phylogenetically and horticulturally important and is distributed throughout the northern hemisphere. GS diversity in Lilium and the underlying evolutionary mechanisms are poorly understood. We performed a comprehensive study involving phylogenetically independent analysis on 71 species to explore the diversity and evolution of GS and its correlation with karyological and environmental traits within Lilium (including Nomocharis). The strong phylogenetic signal detected for GS in the genus provides evidence consistent with that the repetitive DNA may be the primary contributors to the GS diversity, while the significant positive relationships detected between GS and the haploid chromosome length (HCL) provide insights into patterns of genome evolution. The relationships between GS and karyotypes indicate that ancestral karyotypes of Lilium are likely to have exhibited small genomes, low diversity in centromeric index (CVCI) values and relatively high relative variation in chromosome length (CVCL) values. Significant relationships identified between GS and annual temperature and between GS and annual precipitation suggest that adaptation to habitat strongly influences GS diversity. We conclude that GS in Lilium is shaped by both neutral (genetic drift) and adaptive evolution. These findings will have important consequences for understanding the evolution of giant plant genomes, and exploring the role of repetitive DNA fraction and chromosome changes in a plant group with large genomes and conservation of chromosome number.

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Genome Size Diversity in Lilium (Liliaceae) Is Correlated with Karyotype and Environmental Traits

Lilium cernuum is endangered and was listed in the category of key protected wild plants in China. In this study, we report the complete chloroplast genome of L. cernuum using Illumina paired-end sequencing. The entire chloroplast genome maps as a circular molecule of 152,604 bp built with a quadripartite organization: two inverted repeats (IRs) of 26,481 bp separated by a large single copy (LSC) sequence of 82,058 bp and a small single copy (SSC) sequence of 17,584 bp. The chloroplast genome contains the conservative structure present in most Liliaceae chloroplasts composing of 79 protein-coding genes, 30 tRNAs and 4 rRNAs. Among these genes, 15 harbor a single intron, and 2 contain a couple of introns. A maximum likelihood phylogenomic analysis showed that L. cernuum was closely related to L. tsingtauense and L. hansonii that belonged to the family Liliaceae.

The complete chloroplast genome of Lilium cernuum : genome structure and evolution

Lilium fargesii Franchet is an endangered species endemic to China. In this study, the complete chloroplast genome has been generated from the Next Generation Sequencing. The whole genome is 153,235 bp in length, and includes one large single copy region of 82,217 bp, one small single copy region of 17,038 bp and a pair of inverted repeat region of 26,990 bp. It contains 132 genes, comprising 86 protein-coding genes (78 PCG species), 38 transfer RNA (30 tRNA species) and eight ribosomal RNA genes (four rRNA species). In the maximum likelihood tree, all species of Lilium were clustered into two monophyletic groups with 100 % bootstrap value.

Yu Bi

Papers

Chloroplast genomic resources for phylogeny and DNA barcoding: a case study on Fritillaria.

Complete chloroplast genome sequences of Lilium : insights into evolutionary dynamics and phylogenetic analyses

Genome Size Diversity in Lilium (Liliaceae) Is Correlated with Karyotype and Environmental Traits

The complete chloroplast genome of Lilium cernuum : genome structure and evolution

The complete chloroplast genome sequence of Lilium fargesii (Lilium, Liliaceae)