Menu
July 7, 2019

High-coverage sequencing and annotated assemblies of the budgerigar genome.

Parrots belong to a group of behaviorally advanced vertebrates and have an advanced ability of vocal learning relative to other vocal-learning birds. They can imitate human speech, synchronize their body movements to a rhythmic beat, and understand complex concepts of referential meaning to sounds. However, little is known about the genetics of these traits. Elucidating the genetic bases would require whole genome sequencing and a robust assembly of a parrot genome.We present a genomic resource for the budgerigar, an Australian Parakeet (Melopsittacus undulatus) — the most widely studied parrot species in neuroscience and behavior. We present genomic sequence data that includes over 300× raw read coverage from multiple sequencing technologies and chromosome optical maps from a single male animal. The reads and optical maps were used to create three hybrid assemblies representing some of the largest genomic scaffolds to date for a bird; two of which were annotated based on similarities to reference sets of non-redundant human, zebra finch and chicken proteins, and budgerigar transcriptome sequence assemblies. The sequence reads for this project were in part generated and used for both the Assemblathon 2 competition and the first de novo assembly of a giga-scale vertebrate genome utilizing PacBio single-molecule sequencing.Across several quality metrics, these budgerigar assemblies are comparable to or better than the chicken and zebra finch genome assemblies built from traditional Sanger sequencing reads, and are sufficient to analyze regions that are difficult to sequence and assemble, including those not yet assembled in prior bird genomes, and promoter regions of genes differentially regulated in vocal learning brain regions. This work provides valuable data and material for genome technology development and for investigating the genomics of complex behavioral traits.


July 7, 2019

The functions of DNA methylation by CcrM in Caulobacter crescentus: a global approach.

DNA methylation is involved in a diversity of processes in bacteria, including maintenance of genome integrity and regulation of gene expression. Here, using Caulobacter crescentus as a model, we exploit genome-wide experimental methods to uncover the functions of CcrM, a DNA methyltransferase conserved in most Alphaproteobacteria. Using single molecule sequencing, we provide evidence that most CcrM target motifs (GANTC) switch from a fully methylated to a hemi-methylated state when they are replicated, and back to a fully methylated state at the onset of cell division. We show that DNA methylation by CcrM is not required for the control of the initiation of chromosome replication or for DNA mismatch repair. By contrast, our transcriptome analysis shows that >10% of the genes are misexpressed in cells lacking or constitutively over-expressing CcrM. Strikingly, GANTC methylation is needed for the efficient transcription of dozens of genes that are essential for cell cycle progression, in particular for DNA metabolism and cell division. Many of them are controlled by promoters methylated by CcrM and co-regulated by other global cell cycle regulators, demonstrating an extensive cross talk between DNA methylation and the complex regulatory network that controls the cell cycle of C. crescentus and, presumably, of many other Alphaproteobacteria.


July 7, 2019

Draft whole-genome sequences of nine non-O157 Shiga toxin-producing Escherichia coli strains.

Shiga toxin-producing Escherichia coli (STEC) is an important food-borne pathogen. Here, we report the draft whole-genome sequences of nine STEC strains isolated from clinical cases in the United States. This is the first report of such information for STEC of serotypes O69, H11, O145:H25, O118:H16, O91:H21, O146:H21, O45:H2, O128:H2, and O121:H19. Copyright © 2014 Lindsey et al.


July 7, 2019

Quorum sensing activity of Aeromonas caviae strain YL12, a bacterium isolated from compost.

Quorum sensing is a well-studied cell-to-cell communication method that involves a cell-density dependent regulation of genes expression mediated by signalling molecules. In this study, a bacterium isolated from a plant material compost pile was found to possess quorum sensing activity based on bioassay screening. Isolate YL12 was identified using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and molecular typing using rpoD gene which identified the isolate as Aeromonas caviae. High resolution tandem mass spectrometry was subsequently employed to identify the N-acyl homoserine lactone profile of Aeromonas caviae YL12 and confirmed that this isolate produced two short chain N-acyl homoserine lactones, namely C4-HSL and C6, and the production was observed to be cell density-dependent. Using the thin layer chromatography (TLC) bioassay, both AHLs were found to activate C. violaceum CV026, whereas only C6-HSL was revealed to induce bioluminescence expression of E. coli [pSB401]. The data presented in this study will be the leading steps in understanding the role of quorum sensing in Aeromonas caviae strain YL12.


July 7, 2019

Stenotrophomonas comparative genomics reveals genes and functions that differentiate beneficial and pathogenic bacteria.

In recent years, the number of human infections caused by opportunistic pathogens has increased dramatically. Plant rhizospheres are one of the most typical natural reservoirs for these pathogens but they also represent a great source for beneficial microbes with potential for biotechnological applications. However, understanding the natural variation and possible differences between pathogens and beneficials is the main challenge in furthering these possibilities. The genus Stenotrophomonas contains representatives found to be associated with human and plant host.We used comparative genomics as well as transcriptomic and physiological approaches to detect significant borders between the Stenotrophomonas strains: the multi-drug resistant pathogenic S. maltophilia and the plant-associated strains S. maltophilia R551-3 and S. rhizophila DSM14405T (both are biocontrol agents). We found an overall high degree of sequence similarity between the genomes of all three strains. Despite the notable similarity in potential factors responsible for host invasion and antibiotic resistance, other factors including several crucial virulence factors and heat shock proteins were absent in the plant-associated DSM14405T. Instead, S. rhizophila DSM14405T possessed unique genes for the synthesis and transport of the plant-protective spermidine, plant cell-wall degrading enzymes, and high salinity tolerance. Moreover, the presence or absence of bacterial growth at 37°C was identified as a very simple method in differentiating between pathogenic and non-pathogenic isolates. DSM14405T is not able to grow at this human-relevant temperature, most likely in great part due to the absence of heat shock genes and perhaps also because of the up-regulation at increased temperatures of several genes involved in a suicide mechanism.While this study is important for understanding the mechanisms behind the emerging pattern of infectious diseases, it is, to our knowledge, the first of its kind to assess the risk of beneficial strains for biotechnological applications. We identified certain traits typical of pathogens such as growth at the human body temperature together with the production of heat shock proteins as opposed to a temperature-regulated suicide system that is harnessed by beneficials.


July 7, 2019

Methylome diversification through changes in DNA methyltransferase sequence specificity.

Epigenetic modifications such as DNA methylation have large effects on gene expression and genome maintenance. Helicobacter pylori, a human gastric pathogen, has a large number of DNA methyltransferase genes, with different strains having unique repertoires. Previous genome comparisons suggested that these methyltransferases often change DNA sequence specificity through domain movement–the movement between and within genes of coding sequences of target recognition domains. Using single-molecule real-time sequencing technology, which detects N6-methyladenines and N4-methylcytosines with single-base resolution, we studied methylated DNA sites throughout the H. pylori genome for several closely related strains. Overall, the methylome was highly variable among closely related strains. Hypermethylated regions were found, for example, in rpoB gene for RNA polymerase. We identified DNA sequence motifs for methylation and then assigned each of them to a specific homology group of the target recognition domains in the specificity-determining genes for Type I and other restriction-modification systems. These results supported proposed mechanisms for sequence-specificity changes in DNA methyltransferases. Knocking out one of the Type I specificity genes led to transcriptome changes, which suggested its role in gene expression. These results are consistent with the concept of evolution driven by DNA methylation, in which changes in the methylome lead to changes in the transcriptome and potentially to changes in phenotype, providing targets for natural or artificial selection.


July 7, 2019

The Glanville fritillary genome retains an ancient karyotype and reveals selective chromosomal fusions in Lepidoptera.

Previous studies have reported that chromosome synteny in Lepidoptera has been well conserved, yet the number of haploid chromosomes varies widely from 5 to 223. Here we report the genome (393?Mb) of the Glanville fritillary butterfly (Melitaea cinxia; Nymphalidae), a widely recognized model species in metapopulation biology and eco-evolutionary research, which has the putative ancestral karyotype of n=31. Using a phylogenetic analyses of Nymphalidae and of other Lepidoptera, combined with orthologue-level comparisons of chromosomes, we conclude that the ancestral lepidopteran karyotype has been n=31 for at least 140?My. We show that fusion chromosomes have retained the ancestral chromosome segments and very few rearrangements have occurred across the fusion sites. The same, shortest ancestral chromosomes have independently participated in fusion events in species with smaller karyotypes. The short chromosomes have higher rearrangement rate than long ones. These characteristics highlight distinctive features of the evolutionary dynamics of butterflies and moths.


July 7, 2019

Complete genome sequence of Vibrio parahaemolyticus environmental strain UCM-V493.

Vibrio parahaemolyticus is the leading bacterial cause of seafood-related gastroenteritis in the world. Here, we report the complete genome sequence and annotation of an environmental strain of V. parahaemolyticus, UCM-V493, with the aim of understanding the differences between the clinical and environmental isolates of the bacteria. We also make some preliminary sequence comparisons with the clinical strain RIMD2210633.


July 7, 2019

Complete genome sequences of nitrofurantoin-sensitive and -resistant Escherichia coli ST540 and ST2747 strains.

Widespread multidrug resistance in Escherichia coli has necessitated the reintroduction of older antibiotics, such as nitrofurantoin. However, mechanisms by which resistance to nitrofurantoin emerges in E. coli are not well elucidated. Toward this aim, we sequenced two nitrofurantoin-sensitive E. coli sequence types (ST540 and ST2747) and their four nitrofurantoin-resistant derivatives generated in vitro under aerobic and anaerobic growth conditions.


July 7, 2019

Whole-genome sequence of Burkholderia sp. strain RPE67, a bacterial gut symbiont of the bean bug Riptortus pedestris.

Burkholderia sp. strain RPE67 is a bacterial symbiont isolated from a field-collected bean bug, Riptortus pedestris. To understand the genetic basis of the insect-microbe symbiosis, we performed whole-genome sequencing of the Burkholderia strain, revealing an 8.69-Mb genome consisting of three chromosomes and three plasmids. Copyright © 2014 Takeshita et al.


July 7, 2019

Complete genome sequence of Kosakonia sacchari type strain SP1(T.).

Kosakonia sacchari sp. nov. is a new species within the new genus Kosakonia, which was included in the genus Enterobacter. K sacchari is a nitrogen-fixing bacterium named for its association with sugarcane (Saccharum officinarum L.). K sacchari bacteria are Gram-negative, aerobic, non-spore-forming, motile rods. Strain SP1(T) (=CGMCC1.12102(T)=LMG 26783(T)) is the type strain of the K sacchari sp. nov and is able to colonize and fix N2 in association with sugarcane plants, thus promoting plant growth. Here we summarize the features of strain SP1(T) and describe its complete genome sequence. The genome contains a single chromosome and no plasmids, 4,902,024 nucleotides with 53.7% GC content, 4,460 protein-coding genes and 105 RNA genes including 22 rRNA genes, 82 tRNA genes, and 1 ncRNA gene.


Talk with an expert

If you have a question, need to check the status of an order, or are interested in purchasing an instrument, we're here to help.