April 21, 2020  |  

Early Sex-chromosome Evolution in the Diploid Dioecious Plant Mercurialis annua.

Suppressed recombination allows divergence between homologous sex chromosomes and the functionality of their genes. Here, we reveal patterns of the earliest stages of sex-chromosome evolution in the diploid dioecious herb Mercurialis annua on the basis of cytological analysis, de novo genome assembly and annotation, genetic mapping, exome resequencing of natural populations, and transcriptome analysis. The genome assembly contained 34,105 expressed genes, of which 10,076 were assigned to linkage groups. Genetic mapping and exome resequencing of individuals across the species range both identified the largest linkage group, LG1, as the sex chromosome. Although the sex chromosomes of M. annua are karyotypically homomorphic, we estimate that about a third of the Y chromosome has ceased recombining, containing 568 transcripts and spanning 22.3 cM in the corresponding female map. Nevertheless, we found limited evidence for Y-chromosome degeneration in terms of gene loss and pseudogenization, and most X- and Y-linked genes appear to have diverged in the period subsequent to speciation between M. annua and its sister species M. huetii which shares the same sex-determining region. Taken together, our results suggest that the M. annua Y chromosome has at least two evolutionary strata: a small old stratum shared with M. huetii, and a more recent larger stratum that is probably unique to M. annua and that stopped recombining about one million years ago. Patterns of gene expression within the non-recombining region are consistent with the idea that sexually antagonistic selection may have played a role in favoring suppressed recombination.Copyright © 2019, Genetics.


April 21, 2020  |  

Large-scale ruminant genome sequencing provides insights into their evolution and distinct traits.

The ruminants are one of the most successful mammalian lineages, exhibiting morphological and habitat diversity and containing several key livestock species. To better understand their evolution, we generated and analyzed de novo assembled genomes of 44 ruminant species, representing all six Ruminantia families. We used these genomes to create a time-calibrated phylogeny to resolve topological controversies, overcoming the challenges of incomplete lineage sorting. Population dynamic analyses show that population declines commenced between 100,000 and 50,000 years ago, which is concomitant with expansion in human populations. We also reveal genes and regulatory elements that possibly contribute to the evolution of the digestive system, cranial appendages, immune system, metabolism, body size, cursorial locomotion, and dentition of the ruminants. Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.


April 21, 2020  |  

Draft genome assembly and transcriptome sequencing of the golden algae Hydrurus foetidus (Chrysophyceae)

Hydrurusfoetidus is a freshwater alga belonging to the phylum Heterokonta. It thrives in cold rivers in polar and high alpine regions. It has several morphological traits reminiscent of single-celled eukaryotes, but can also form macroscopic thalli. Despite its ability to produce polyunsaturated fatty acids, its life under cold conditions and its variable morphology, very little is known about its genome and transcriptome. Here, we present an extensive set of next-generation sequencing data, including genomic short reads from Illumina sequencing and long reads from Nanopore sequencing, as well as full length cDNAs from PacBio IsoSeq sequencing and a small RNA dataset (smaller than 200 bp) sequenced with Illumina. We combined this data with, to our knowledge, the first draft genome assembly of a chrysophyte algae. The assembly consists of 5069 contigs to a total assembly size of 171 Mb and a 77% BUSCO completeness. The new data generated here may contribute to a better understanding of the evolution and ecological roles of chrysophyte algae, as well as to resolve the branching patterns within the Heterokonta.


April 21, 2020  |  

Draft Genome Sequence of Dicyma pulvinata Strain 414-3, a Mycoparasite of Cladosporium fulvum, Causal Agent of Tomato Leaf Mold.

Dicyma pulvinata strain 414-3, isolated from the surface of a tomato leaf, is a mycoparasitic fungus of Cladosporium fulvum, which causes leaf mold of tomato. We report here the draft genome sequence of strain 414-3, which will contribute to elucidating the molecular mechanisms involved in the mycoparasitism.Copyright © 2019 Sushida et al.


April 21, 2020  |  

Complete Genome Sequence of Subcluster 5.2 Synechococcus sp. Strain CB0101, Isolated from the Chesapeake Bay.

Synechococcus sp. strain CB0101 is a model strain for cyanobacteria living in the estuarine environment. It is also a representative member of marine Synechococcus subcluster 5.2. The draft genome sequence of CB0101 was reported in 2014 with 454 sequencing. Here, we report the complete genome sequence of CB0101, obtained with PacBio sequencing. CB0101 contains a specialized array of genes which are involved in sensing, responding to, and persisting in the presence of environmental stress.Copyright © 2019 Fucich et al.


April 21, 2020  |  

Draft Genome Sequence of Streptomyces sp. Strain RKND-216, an Antibiotic Producer Isolated from Marine Sediment in Prince Edward Island, Canada.

Streptomyces sp. strain RKND-216 was isolated from marine sediment collected in Prince Edward Island, Canada, and produces a putatively novel bioactive natural product with antitubercular activity. The genome assembly consists of two contigs covering 5.61?Mb. Genome annotation identified 4,618 predicted protein-coding sequences and 19 predicted natural product biosynthetic gene clusters.Copyright © 2019 Liang et al.


April 21, 2020  |  

Draft Genome Sequence of Bifidobacterium longum ZJ1, Isolated from a Centenarian in Anhui, China.

Here, we present the complete genome sequence of a Bifidobacterium longum isolate, that of strain ZJ1, and this strain showed a cholesterol degradation ability that is greater than that of five strains we chose for comparison (Bifidobacterium longum 536, B. infantis 1912, B. longum 1941, B. breve ATCC 15698, B. infantis ATCC 17930). The draft genome of strain ZJ1 consists of 2,414,672?bp, with 2,042 protein-coding genes, 69 noncoding RNA genes, and 60.16% G+C content.Copyright © 2019 Jin et al.


April 21, 2020  |  

High-Quality Draft Genome Sequence of Fusarium oxysporum f. sp. cubense Strain 160527, a Causal Agent of Panama Disease.

Fusarium oxysporum f. sp. cubense is the causal agent of banana Fusarium wilt, also known as Panama disease. Here, we present a high-quality genome sequence of F. oxysporum f. sp. cubense strain 160527. The genome assembly is composed of 12 contigs with a total assembly length of 51,139,495?bp (N50 contig length, 4,884,632?bp). Copyright © 2019 Asai et al.


April 21, 2020  |  

Draft Genome Sequence of Methylocystis heyeri H2T, a Methanotroph with Habitat-Specific Adaptations, Isolated from a Peatland Ecosystem.

Methylocystis heyeri H2T is an aerobic facultative methanotroph which was isolated from an acidic Sphagnum peat bog lake and is a common inhabitant of peatland ecosystems. This bacterium possesses two particulate methane monooxygenases with low and high affinity to methane and a number of genomic adaptations to acidic conditions.Copyright © 2019 Oshkin et al.


April 21, 2020  |  

Draft Genome Sequences of Shiga Toxin-Producing Escherichia coli O157:H7 Strains Recovered from a Major Production Region for Leafy Greens in California.

Shiga toxin-producing Escherichia coli O157:H7 is a foodborne pathogen and is responsible for outbreaks of human gastroenteritis. This report documents the draft genome sequences of nine O157:H7 cattle strains, which were identified to be PCR positive for a Shiga toxin gene but displayed different levels of functional toxin activity.


April 21, 2020  |  

Complete Whole-Genome Sequences of Two Raoultella terrigena Strains, NCTC 13097 and NCTC 13098, Isolated from Human Cases.

Raoultella terrigena is a bacterial species associated with soil and aquatic environments; however, sporadic cases of opportunistic disease in humans have been reported. Here, we report the first two complete genome sequences from clinical strains isolated from human sources that have been deposited in the National Collection of Type Cultures (NCTC). © Crown copyright 2019.


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