Genome Sequence Assembly Research Articles

Photoreceptor genes in a trechine beetle, Trechiama kuznetsovi, living in the upper hypogean zone

To address how organisms adapt to a new environment, subterranean organisms whose ancestors colonized subterranean habitats from surface habitats have been studied. Photoreception abilities have been shown to have degenerated in organisms living in caves and calcrete aquifers. Meanwhile, the organisms living in a shallow subterranean environment, which are inferred to reflect an intermediate stage in an evolutionary pathway to colonization of a deeper subterranean environment, have not been studied well. In the present study, we examined the photoreception ability in a trechine beetle, Trechiama kuznetsovi, which inhabits the upper hypogean zone and has a vestigial compound eye. By de novo assembly of genome and transcript sequences, we were able to identify photoreceptor genes and phototransduction genes. Specifically, we focused on opsin genes, where one long wavelength opsin gene and one ultraviolet opsin gene were identified. The encoded amino acid sequences had neither a premature stop codon nor a frameshift mutation, and appeared to be subject to purifying selection. Subsequently, we examined the internal structure of the compound eye and nerve tissue in the adult head, and found potential photoreceptor cells in the compound eye and nerve bundle connected to the brain. The present findings suggest that T. kuznetsovi has retained the ability of photoreception. This species represents a transitional stage of vision, in which the compound eye regresses, but it may retain the ability of photoreception using the vestigial eye.

Draft genome sequence of potato crop bacterial isolates and nanoparticles-intervention for the induction of secondary metabolites biosynthesis

IntroductionInsights about the effects of gold nanoparticles (AuNPs) on the biosynthetic manipulation of unknown microbe secondary metabolites could be a promising technique for prospective research on nano-biotechnology. AimIn this research, we aimed to isolate a fresh, non-domesticated unknown bacterium strain from a common scab of potato crop located in Saudi Arabia and study the metabolic profile. MethodologyThis was achieved through genomic DNA (gDNA) sequencing using Oxford Nanopore Technology. The genomic data were subjected to several bioinformatics tools, including canu-1.9 software, Prokka, DFAST, Geneious Prime, and AntiSMASH. We exposed the culture of the bacterial isolate with different concentrations of AuNPs and investigated the effects of AuNPs on secondary metabolites biosynthesis using several analytical techniques. Furthermore, Tandem-mass spectrometric (MS/MS) technique was optimized for the characterization of several significant sub-classes. ResultsThe genomic draft sequence assembly, alignment, and annotation have verified the bacterial isolate as Priestia megaterium. This bacterium has secondary metabolites related to different biosynthetic gene clusters. AuNPs intervention showed an increase in the production of compounds with the molecular weights of 254 and 270 Da in a direct-dependent manner with the increase of the AuNPs concentrations. ConclusionThe increase in the yields of compound 1 and 2 concomitantly with the increase in the concentration of the added AuNPs provide evidences about the effects of nanoparticles on the biosynthesis of the secondary metabolites. It contributes to the discovery of genes involved in different biosynthetic gene clusters (BGCs) and prediction of the structures of the natural products.

Elucidating the genomic history of commercially used Bacillus thuringiensis subsp. tenebrionis strain NB176.

Bacillus thuringiensis subsp. tenebrionis (Btt) produces a coleopteran-specific crystal protoxin protein (Cry3Aa δ-endotoxin). After its discovery in 1982, the strain NB125 (DSM 5526) was eventually registered in 1990 to control the Colorado potato beetle (Leptinotarsa decemlineata). Gamma-irradiation of NB125 resulted in strain NB176-1 (DSM 5480) that exhibited higher cry3Aa production and became the active ingredient of the plant protection product Novodor® FC. Here, we report a comparative genome analysis of the parental strain NB125, its derivative NB176-1 and the current commercial production strain NB176. The entire genome sequences of the parental and derivative strains were deciphered by a hybrid de novo approach using short (Illumina) and long (Nanopore) read sequencing techniques. Genome assembly revealed a chromosome of 5.4 to 5.6 Mbp and six plasmids with a size range from 14.9 to 250.5 kbp for each strain. The major differences among the original NB125 and the derivative strains NB176-1 and NB176 were an additional copy of the cry3Aa gene, which translocated to another plasmid as well as a chromosomal deletion (~ 178 kbp) in NB176. The assembled genome sequences were further analyzed in silico for the presence of virulence and antimicrobial resistance (AMR) genes.

Genome-wide characterization of R2R3-MYB gene family in Santalum album and their expression analysis under cold stress.

Sandalwood (Santalum album) is a high-value multifunctional tree species that is rich in aromatic substances and is used in medicine and global cosmetics. Due to the scarcity of land resources in tropical and subtropical regions, land in temperate regions is a potential resource for the development of S. album plantations in order to meet the needs of S. album production and medicine. The R2R3-MYB transcription factor family is one of the largest in plants and plays an important role in the response to various abiotic stresses. However, the R2R3-MYB gene family of S. album has not been studied. In this study, 144 R2R3-MYB genes were successfully identified in the assembly genome sequence, and their characteristics and expression patterns were investigated under various durations of low temperature stress. According to the findings, 31 of the 114 R2R3-MYB genes showed significant differences in expression after cold treatment. Combining transcriptome and weighted gene co-expression network analysis (WGCNA) revealed three key candidate genes (SaMYB098, SaMYB015, and SaMYB068) to be significantly involved in the regulation of cold resistance in S. album. The structural characteristics, evolution, and expression pattern of the R2R3-MYB gene in S. album were systematically examined at the whole genome level for the first time in this study. It will provide important information for future research into the function of the R2R3-MYB genes and the mechanism of cold stress response in S. album.

A chromosome-level genome assembly of an early matured aromatic Japonica rice variety Qigeng10 to accelerate rice breeding for high grain quality in Northeast China.

Early-matured aromatic japonica rice from the Northeast is the most popular rice commodity in the Chinese market. The Qigeng10 (QG10) was one of the varieties with the largest planting area in this region in recent years. It was an early-matured japonica rice variety with a lot of superior traits such as semi-dwarf, lodging resistance, long grain, aromatic and good quality. Therefore, a high-quality assembly of Qigeng10 genome is critical and useful for japonica research and breeding. In this study, we produced a high-precision QG10 chromosome-level genome by using a combination of Nanopore and Hi-C platforms. Finally, we assembled the QG10 genome into 77 contigs with an N50 length of 11.80 Mb in 27 scaffolds with an N50 length of 30.55 Mb. The assembled genome size was 378.31Mb with 65 contigs and constituted approximately 99.59% of the 12 chromosomes. We identified a total of 1,080,819 SNPs and 682,392 InDels between QG10 and Nipponbare. We also annotated 57,599 genes by the Ab initio method, homology-based technique, and RNA-seq. Based on the assembled genome sequence, we detected the sequence variation in a total of 63 cloned genes involved in grain yield, grain size, disease tolerance, lodging resistance, fragrance, and many other important traits. Finally, we identified five elite alleles (qTGW2Nipponbare , qTGW3Nanyangzhan , GW5IR24 , GW6Suyunuo , and qGW8Basmati385 ) controlling long grain size, four elite alleles (COLD1Nipponbare , bZIP73Nipponbare , CTB4aKunmingxiaobaigu , and CTB2Kunmingxiaobaigu ) controlling cold tolerance, three non-functional alleles (DTH7Kitaake , Ghd7Hejiang19 , and Hd1Longgeng31 ) for early heading, two resistant alleles (PiaAkihikari and Pid4Digu ) for rice blast, a resistant allele STV11Kasalath for rice stripe virus, an NRT1.1BIR24 allele for higher nitrate absorption activity, an elite allele SCM3Chugoku117 for stronger culms, and the typical aromatic gene badh2-E2 for fragrance in QG10. These results not only help us to better elucidate the genetic mechanisms underlying excellent agronomic traits in QG10 but also have wide-ranging implications for genomics-assisted breeding in early-matured fragrant japonica rice.

Morphological and molecular characterisation of Trachactinolaimus nanjingensis n. sp. (Dorylaimida: Actinolaimidae) from Nanjing, China

Summary Trachactinolaimus nanjingensis n. sp. isolated from mosses at the Yangshan Quarry Park in Nanjing, P.R. China, is described. It is characterised by 3.01 (2.64-3.42) mm long female and 2.84 (2.50-3.22) mm long male, four onchia with numerous mural denticles (>100), vulva with a transverse slit, 15-19 contiguous ventromedian supplements, spicules length of 61.5 (54.6-64.3) μm, and female and male both having long tail, with c′ values equal to 5.0-9.2 and 2.3-3.5, respectively. The new species was morphologically compared with T. brevicaudatus, T. dominicus, T. montanus and T. radulatus. The sequences of 18S and 28S rRNA genes of the new species were obtained using regular PCR amplification, while the ITS and mtCOI sequences were extracted from the whole genome sequencing assembly. The phylogenetic relationships of the new species were reconstructed using 18S and 28S sequences and the status of the new species was discussed. The 18S and 28S sequences of a population of genus Westindicus recovered during the present study were also obtained. This is the first time to present the ITS and mtCOI sequences of family Actinolaimidae.

Clustered cases of human adenovirus types 4, 7, and 14 infections in US Department of Defense Beneficiaries during the 2018–2019 season

Human adenoviruses (HAdV) are genetically diverse and can infect a number of tissues with severities varied from mild to fatal. HAdV types 3, 4, 7, 11, 14, 21, and 55 were associated with acute respiratory illnessesoutbreaks in the United States and in other countries. The risk of outbreaks can be effectively controlled by HAdV vaccination or mitigated by screening and preventive measures. During the influenza season 2018-2019, the DoD Global Respiratory Pathogen Surveillance Program (DoDGRS) received 24 300 respiratory specimens. HAdV samples that produced positive cytopathic effects in viral cultivation were subjected to next-generation sequencing for genome sequence assembly, genome typing, whole genome phylogeny, and sequence comparative analyses. A variety of HAdV types were identified in this study, including HAdV types 1-7, 14, 55, and 56. HAdV types 4, 7, and 14 were found in clustered cases in Colorado, Florida, New York, and South Carolina. Comparative sequence analyses of these isolates revealed the emergence of novel genetic mutations despite the stability of adenovirus genomes. Genomic surveillance of HAdV suggested possible undetected outbreaks and shed light on prevalence, genetic divergence, and viral evolution of HAdV. Continued surveillance will inform risk assessment and countermeasures.

Prevalence and Characterization of CRISPR Locus 2.1 Spacers in Escherichia coli Isolates Obtained from Feces of Animals and Humans.

The clustered regularly interspaced short palindromic repeat (CRISPR) has been studied as an immune system in prokaryotes for the survival of bacteriophages. The CRISPR system in prokaryotes records the invasion of bacteriophages or other genetic materials in CRISPR loci. Accordingly, CRISPR loci can reveal a history of infection records of bacteriophages and other genetic materials. Therefore, identification of the CRISPR array may help trace the events that bacteria have undergone. In this study, we characterized and identified the spacers of the CRISPR loci in Escherichia coli isolates obtained from the feces of animals and humans. Most CRISPR spacers were found to stem from phages. Although we did not find any patterns in CRISPR spacers according to sources, our results showed that phage-derived spacers mainly originated from the families Inoviridae, Myoviridae, Podoviridae, and Siphoviridae and the order Caudovirales, whereas plasmid-derived CRISPR spacers were mainly from the Enterobacteriaceae family. In addition, it is worth noting that the isolates from each animal and human source harbored source-specific spacers. Considering that some of these taxa are likely found in the gut of mammalian animals, CRISPR spacers identified in these E. coli isolates were likely derived from the bacteriophageome and microbiome in closed gut environments. Although the bacteriophageome database limits the characterization of CRISPR arrays, the present study showed that some spacers were specifically found in both animal and human sources. Thus, this finding may suggest the possible use of E. coli CRISPR spacers as a microbial source tracking tool. IMPORTANCE We characterized spacers of CRISPR locus 2.1 in E. coli isolates obtained from the feces of various sources. Phage-derived CRISPR spacers are mainly acquired from the order Caudovirales, and plasmid-derived CRISPR spacers are mostly from the Enterobacteriaceae family. This is thought to reflect the microbiome and phageome of the gut environment of the sources. Hence, spacers may help track the encounter of bacterial cells with bacterial cells, viruses, or other genetic materials. Interestingly, source-specific spacers are also observed. The identification of source-specific spacers is thought to help develop the methodology of microbial source tracking and understanding the interactions between viruses and bacteria. However, very few spacers have been uncovered to track where they originate. The accumulation of genome sequences can help identify the hosts of spacers and can be applied for microbial source tracking.

Genomic Sequence of Canadian Chenopodium berlandieri: A North American Wild Relative of Quinoa.

Chenopodium berlandieri (pitseed goosefoot) is a widespread native North American plant, which was cultivated and consumed by indigenous peoples prior to the arrival of European colonists. Chenopodium berlandieri is closely related to, and freely hybridizes with the domesticated South American food crop C. quinoa. As such it is a potential source of wild germplasm for breeding with C. quinoa, for improved quinoa production in North America. The C. berlandieri genome sequence could also be a useful source of information for improving quinoa adaptation. To this end, we first optimized barcode markers in two chloroplast genes, rbcL and matK. Together these markers can distinguish C. berlandieri from the morphologically similar Eurasian invasive C. album (lamb's quarters). Second, we performed whole genome sequencing and preliminary assembly of a C. berlandieri accession collected in Manitoba, Canada. Our assembly, while fragmented, is consistent with the expected allotetraploid structure containing diploid Chenopodium sub-genomes A and B. The genome of our accession is highly homozygous, with only one variant site per 3-4000 bases in non-repetitive sequences. This is consistent with predominant self-fertilization. As previously reported for the genome of a partly domesticated Mexican accession of C. berlandieri, our genome assembly is similar to that of C. quinoa. Somewhat unexpectedly, the genome of our accession had almost as many variant sites when compared to the Mexican C. berlandieri, as compared to C. quinoa. Despite the overall similarity of our genome sequence to that of C. quinoa, there are differences in genes known to be involved in the domestication or genetics of other food crops. In one example, our genome assembly appears to lack one functional copy of the SOS1 (salt overly sensitive 1) gene. SOS1 is involved in soil salinity tolerance, and by extension may be relevant to the adaptation of C. berlandieri to the wet climate of the Canadian region where it was collected. Our genome assembly will be a useful tool for the improved cultivation of quinoa in North America.

Bulked Oligo-FISH for Chromosome Painting and Chromosome Barcoding.

Recently developed bulked oligo-FISH is a highly versatile method, which is applicable in any plant species with an assembled genome sequence. This technique allows in situ identification of individual chromosomes, large chromosomal rearrangements, comparative karyotype analysis, or even the reconstruction of the three-dimensional organization of the genome. The method is based on the identification of thousands of short oligonucleotides, unique to specific genome regions, which are synthesized in parallel, fluorescently labeled and used as probes for FISH. In this chapter, we propose a detailed protocol for amplification and labeling of single-stranded oligo-based painting probes from so-called MYtags immortal libraries, the preparation of mitotic metaphase and meiotic pachytene chromosome spreads, and a protocol for the fluorescence in situ hybridization procedure using the synthetic oligo probes. The proposed protocols are demonstrated for banana (Musa spp.).

MEGAnnotator2: a pipeline for the assembly and annotation of microbial genomes.

The reconstruction of microbial genome sequences by bioinformatic pipelines and the consequent functional annotation of their genes' repertoire are fundamental activities aiming at unveiling their biological mechanisms, such as metabolism, virulence factors, and antimicrobial resistances. Here, we describe the development of the MEGAnnotator2 pipeline able to manage all next-generation sequencing methodologies producing short- and long-read DNA sequences. Starting from raw sequencing data, the updated pipeline can manage multiple analyses leading to the assembly of high-quality genome sequences and the functional classification of their genetic repertoire, providing the user with a useful report constituting features and statistics related to the microbial genome. The updated pipeline is fully automated from the installation to the delivery of the output, thus requiring minimal bioinformatics knowledge to be executed.

Flow Sorting-Assisted Optical Mapping.

Optical mapping-a technique that visualizes short sequence motives along DNA molecules of hundred kilobases to megabase in size-has found an important place in genome research. It is widely used to facilitate genome sequence assemblies and analyses of genome structural variations. Application of the technique is conditional on availability of highly pure ultra-long high-molecular-weight DNA (uHMW DNA), which is challenging to achieve in plants due to the presence of the cell wall, chloroplasts, and secondary metabolites, just as a high content of polysaccharides and DNA nucleases in some species. These obstacles can be overcome by employment of flow cytometry, enabling a fast and highly efficient purification of cell nuclei or metaphase chromosomes, which are afterward embedded in agarose plugs and used to isolate the uHMW DNA in situ. Here, we provide a detailed protocol for the flow sorting-assisted uHMW DNA preparation that has been successfully used to construct whole-genome as well as chromosomal optical maps for 20 plant species from several plant families.

Genome Sequence Resource of Trichothecium roseum (ZM-Tr2021), the Causal Agent of Postharvest Pink Rot.

Trichothecium roseum is an economically and agriculturally important fungal pathogen that causes postharvest pink rot on a variety of fruits and vegetables. In addition, it is a biocontrol agent against insects and phytopathogens. However, few genome-sequence resources of T. roseum are publicly available, and this has likely limited progress in understanding genes involved in pathogenicity and other processes in the fungus. In the current study, we used Illumina and PacBio DNA sequencing technologies to generate a chromosome-scale genome sequence assembly of a T. roseum strain (ZM-Tr2021) isolated from colonies of the wheat powdery mildew, Blumeria graminis f. sp. tritici, in China. In total, 26.06 Gb polymerase reads for raw data and 25.86 Gb subreads were obtained. These reads were processed into a 33.80 Mb genome assembly containing 19 contigs, resulting in nine superscaffolds that likely correspond to nearly full-length chromosomes, with an N50 of 4.31 Mb and scaffold lengths ranging from 2.02 Mb to 6.06 Mb. Combining the data of transcriptome and genome, we predicted 8695 protein-coding genes, of which 8488 genes were annotated with known functions. To the best of our knowledge, this is the first chromosome-scale genome of a Trichothecium species. The assembled genome sequence will facilitate studies of comparative genomics, genome evolution, pathogenicity and parasitism of T. roseum and, thereby, provide insights into control of crop diseases caused by the fungus and its use as a biocontrol agent.

Draft Genome Sequence of a Sulfur-Oxidizing Bacterium, Aquamicrobium lusatiense NLF2-7, Isolated from Livestock Wastewater.

Here, we report the draft genome sequence of Aquamicrobium lusatiense NLF2-7, a Gram-negative, aerobic, non-flagellum-forming, rod-shaped bacterium that was isolated from livestock wastewater in South Korea. The assembled genome sequence is 5,201,486 bp, with 4,972 protein-coding sequences in 12 contigs, and possess the genes for the sulfur oxidation pathway.

2197. Genomic Surveillance for Human Adenovirus Infections among Department of Defense Beneficiaries in the 2018-2019 Season

Abstract Background Human adenoviruses (family Adenoviridae, genus Mastadenovirus) (HAdV) species B, C and E cause acute respiratory illnesses (ARI). In particular, respiratory HAdV types 3, 4, 7, 11, 14, 21 and 55 were associated with ARI outbreaks in the US and in other countries. The risk of outbreaks can be effectively controlled by implementation of the live HAdV types 4 and 7 vaccines or mitigated by screening and preventive measures. Methods During the influenza season 2018 – 2019, the DoD Global Respiratory Pathogen Surveillance Program (DoDGRS) received 24,300 specimens from its surveillance network. In total, 322 (1.3%) respiratory specimens were positive for HAdV in molecular assays. HAdV samples that produced positive cytopathic effects (CPE) in subsequent viral cultivation were subjected to next-gen sequencing (NGS) for genome sequence assembly, HAdV genome typing, whole genome phylogeny, and sequence comparative analyses to identify sequence insertions, deletions and amino acid mutations. Results Out of 166 viral culture samples available for NGS, whole genome sequences were obtained for 161 isolates. A variety types of HAdV were identified, including HAdV-1 (N = 15), HAdV-2 (N = 26), HAdV-3 (N = 60), HAdV-4 (N = 13), HAdV-5 (N = 6), HAdV-6 (N = 3), HAdV-7 (N = 12), HAdV-14 (N = 10), HAdV-55 (N = 1), and HAdV-56 (N = 1). HAdV types 4, 7 and 14, which were reported causing ARI outbreaks in the US military and other congregate settings, were found in clustered cases in several US states. Comparative sequence analyses of these isolates revealed the emergence of novel genetic mutations despite the stability of adenovirus genomes. Conclusion Routine clinical respiratory pathogen diagnostics or molecular surveillance of respiratory diseases detect adenovirus without determination of HAdV type. Human adenoviruses are genetically diverse and can infect a number of tissues with severities varied from mild to fatal. Enhanced genomic surveillance of HAdV in the US and worldwide will shed light on prevalence, genetic divergence, and viral evolution of human adenoviruses and inform timely risk assessment and countermeasures. Disclosures All Authors: No reported disclosures.

Genome Sequence Resource of Fusarium graminearum TaB10 and Fusarium avenaceum KA13, Causal Agents of Stored Apple Rot.

The filamentous fungus Fusarium graminearum is a well-known cereal pathogen and F. avenaceum is a pathogen with a wide host range. Recently, both species were reported as causal agents of apple rot, raising concerns about postharvest yield losses and mycotoxin contamination. Here, we report genome assemblies of F. avenaceum KA13 and F. graminearum TaB10, both isolated from fruits with symptoms of apple rot. The final F. avenaceum KA13 genome sequence assembly of 41.7 Mb consists of 34 scaffolds, with an N50 value of 2.2 Mb and 15,886 predicted genes. The total size of the final F. graminearum TaB10 assembly is 36.76 Mb, consisting of 54 scaffolds with an N50 value of 1.7 Mb, and it consists of 14,132 predicted genes. These new genomes provide valuable resources to better understand plant-microbe interaction in stored apple rot disease. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Enhanced Arbovirus Surveillance with High-Throughput Metatranscriptomic Processing of Field-Collected Mosquitoes.

Surveillance programs are essential for the prevention and control of mosquito-borne arboviruses that cause serious human and animal diseases. Viral metatranscriptomic sequencing can enhance surveillance by enabling untargeted, high-throughput arbovirus detection. We used metatranscriptomic sequencing to screen field-collected mosquitoes for arboviruses to better understand how metatranscriptomics can be utilised in routine surveillance. Following a significant flood event in 2016, more than 56,000 mosquitoes were collected over seven weeks from field traps set up in Victoria, Australia. The traps were split into samples of 1000 mosquitoes or less and sequenced on the Illumina HiSeq. Five arboviruses relevant to public health (Ross River virus, Sindbis virus, Trubanaman virus, Umatilla virus, and Wongorr virus) were detected a total of 33 times in the metatranscriptomic data, with 94% confirmed using reverse transcription quantitative PCR (RT-qPCR). Analysis of metatranscriptomic cytochrome oxidase I (COI) sequences enabled the detection of 12 mosquito and two biting midge species. Screening of the same traps by an established public health arbovirus surveillance program corroborated the metatranscriptomic arbovirus and mosquito species detections. Assembly of genome sequences from the metatranscriptomic data also led to the detection of 51 insect-specific viruses, both known and previously undescribed, and allowed phylogenetic comparison to past strains. We have demonstrated how metatranscriptomics can enhance surveillance by enabling untargeted arbovirus detection, providing genomic epidemiological data, and simultaneously identifying vector species from large, unsorted mosquito traps.

Towards a Genetic Linkage Map of the California Condor, an Endangered New World Vulture Species.

The development of a linkage map is an important component for promoting genetic and genomic studies in California condors, an endangered New World vulture species. Using a set of designed anonymous microsatellite markers, we genotyped a reference condor population involving 121 individuals. After marker validation and genotype filtering, the genetic linkage analysis was performed using 123 microsatellite loci. This resulted in the identification of 15 linkage groups/subgroups that formed a first-generation condor genetic map, while no markers linked to a lethal chondrodystrophy mutation were found. A panel of polymorphic markers that is instrumental in molecular parentage diagnostics and other genetic studies in the California condor was selected. Further condor conservation genomics research will be focused on updating the linkage map and integrating it with cytogenetic and BAC-based physical maps and ultimately with the genome sequence assembly.

Chromosome-level genome assembly reveals potential epigenetic mechanisms of the thermal tolerance in the oriental fruit fly, Bactrocera dorsalis

The oriental fruit fly, Bactrocera dorsalis (Hendel), has very strong ecological adaptability and phenotypic plasticity. Here, the genome of B. dorsalis was assembled into 549.45 Mb sequences with a contig N50 length of 12.81 Mb. Among, 95.67 % assembled genome sequences were anchored on six chromosomes with an N50 length of 94.63 Mb. According to the basic characteristics of the sex chromosomes of Tephritidae, the X chromosome of B. dorsalis was identified. Significant gene expansions were detected in several important gene families related to adaptability. In particular, we annotated 50 histone modification enzymes (HMEs) in this genome. A comparative transcriptome analysis indicated that 12 HME genes were differentially expressed in two thermo-tolerant strains (heat and cold). Interestingly, four and seven of the 12 HME genes responded to heat shock or cold hardening, respectively. These evidences suggested that the histone modification as an epigenetic modification may be involved in the thermal tolerance of B. dorsalis, but with different regulation mechanisms in thermal acclimation and hardening. The high quality genome of B. dorsalis provides an invaluable resource for further functional genomic study. Moreover, comparative genomic analysis will shed insights on revealing the mechanisms of adaptive evolution in this fly.

De novo genome assembly and analysis of Zalaria sp. Him3, a novel fructooligosaccharides producing yeast

BackgroundZalaria sp. Him3 was reported as a novel fructooligosaccharides (FOS) producing yeast. However, Zalaria spp. have not been widely known and have been erroneously classified as a different black yeast, Aureobasidium pullulans. In this study, de novo genome assembly and analysis of Zalaria sp. Him3 was demonstrated to confirm the existence of a potential enzyme that facilitates FOS production and to compare with the genome of A. pullulans.ResultsThe genome of Zalaria sp. Him3 was analyzed; the total read bases and total number of reads were 6.38 Gbp and 42,452,134 reads, respectively. The assembled genome sequence was calculated to be 22.38 Mbp, with 207 contigs, N50 of 885,387, L50 of 10, GC content of 53.8%, and 7,496 genes. g2419, g3120, and g3700 among the predicted genes were annotated as cellulase, xylanase, and β-fructofuranosidase (FFase), respectively. When the read sequences were mapped to A. pullulans EXF-150 genome as a reference, a small amount of reads (3.89%) corresponded to the reference genome. Phylogenetic tree analysis, which was based on the conserved sequence set consisting of 2,362 orthologs in the genome, indicated genetic differences between Zalaria sp. Him3 and Aureobasidium spp.ConclusionThe differences between Zalaria and Aureobasidium spp. were evident at the genome level. g3700 identified in the Zalaria sp. Him3 likely does not encode a highly transfructosyl FFase because the motif sequences were unlike those in other FFases involved in FOS production. Therefore, strain Him3 may produce another FFase. Furthermore, several genes with promising functions were identified and might elicit further interest in Zalaria yeast.