Project description:Bursaphelenchus okinawaensis is a self-fertilizing, hermaphroditic, fungus-feeding nematode used as a laboratory model for the genus Bursaphelenchus, which includes the important pathogen Bursaphelenchus xylophilus Here, we report the nearly complete genome sequence of B. okinawaensis The 70-Mbp assembly contained six scaffolds (>11 Mbp each) with telomere repeats on their ends, indicating complete chromosomes.
Project description:Background Trichoderma is a genus of fungi in the family Hypocreaceae and includes species known to produce enzymes with commercial use. They are largely found in soil and terrestrial plants. Recently, Trichoderma simmonsii isolated from decaying bark and decorticated wood was newly identified in the Harzianum clade of Trichoderma. Due to a wide range of applications in agriculture and other industries, genomes of at least 12 Trichoderma spp. have been studied. Moreover, antifungal and enzymatic activities have been extensively characterized in Trichoderma spp. However, the genomic information and bioactivities of T. simmonsii from a particular marine-derived isolate remain largely unknown. While we screened for asparaginase-producing fungi, we observed that T. simmonsii GH-Sj1 strain isolated from edible kelp produced asparaginase. In this study, we report a draft genome of T. simmonsii GH-Sj1 using Illumina and Oxford Nanopore technologies. Furthermore, to facilitate biotechnological applications of this species, RNA-sequencing was performed to elucidate the transcriptional profile of T. simmonsii GH-Sj1 in response to asparaginase-rich conditions. Results We generated ~ 14 Gb of sequencing data assembled in a ~ 40 Mb genome. The T. simmonsii GH-Sj1 genome consisted of seven telomere-to-telomere scaffolds with no sequencing gaps, where the N50 length was 6.4 Mb. The total number of protein-coding genes was 13,120, constituting ~ 99% of the genome. The genome harbored 176 tRNAs, which encode a full set of 20 amino acids. In addition, it had an rRNA repeat region consisting of seven repeats of the 18S-ITS1–5.8S-ITS2–26S cluster. The T. simmonsii genome also harbored 7 putative asparaginase-encoding genes with potential medical applications. Using RNA-sequencing analysis, we found that 3 genes among the 7 putative genes were significantly upregulated under asparaginase-rich conditions. Conclusions The genome and transcriptome of T. simmonsii GH-Sj1 established in the current work represent valuable resources for future comparative studies on fungal genomes and asparaginase production. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-08162-4.
Project description:With the arrival of telomere-to-telomere (T2T) assemblies of the human genome comes the computational challenge of efficiently and accurately constructing multiple genome alignments at an unprecedented scale. By identifying nucleotides across genomes which share a common ancestor, multiple genome alignments commonly serve as the bedrock for comparative genomics studies. In this review, we provide an overview of the algorithmic template that most multiple genome alignment methods follow. We also discuss prospective areas of improvement of multiple genome alignment for keeping up with continuously arriving high-quality T2T assembled genomes and for unlocking clinically-relevant insights.
Project description:Phaeodactylum tricornutum is a marine diatom with a growing genetic toolbox available and is being used in many synthetic biology applications. While most of the genome has been assembled, the currently available genome assembly is not a completed telomere-to-telomere assembly. Here, we used Oxford Nanopore long reads to build a telomere-to-telomere genome for Phaeodactylum tricornutum. We developed a graph-based approach to extract all unique telomeres, and used this information to manually correct assembly errors. In total, we found 25 nuclear chromosomes that comprise all previously assembled fragments, in addition to the chloroplast and mitochondrial genomes. We found that chromosome 19 has filtered long-read coverage and a quality estimate that suggests significantly less haplotype sequence variation than the other chromosomes. This work improves upon the previous genome assembly and provides new opportunities for genetic engineering of this species, including creating designer synthetic chromosomes.
Project description:BackgroundAnatidae contains numerous waterfowl species with great economic value, but the genetic diversity basis remains insufficiently investigated. Here, we report a chromosome-level genome assembly of Lion-head goose (Anser cygnoides), a native breed in South China, through the combination of PacBio, Bionano, and Hi-C technologies.FindingsThe assembly had a total genome size of 1.19 Gb, consisting of 1,859 contigs with an N50 length of 20.59 Mb, generating 40 pseudochromosomes, representing 97.27% of the assembled genome, and identifying 21,208 protein-coding genes. Comparative genomic analysis revealed that geese and ducks diverged approximately 28.42 million years ago, and geese have undergone massive gene family expansion and contraction. To identify genetic markers associated with body weight in different geese breeds, including Wuzong goose, Huangzong goose, Magang goose, and Lion-head goose, a genome-wide association study was performed, yielding an average of 1,520.6 Mb of raw data that detected 44,858 single-mucleotide polymorphisms (SNPs). Genome-wide association study showed that 6 SNPs were significantly associated with body weight and 25 were potentially associated. The significantly associated SNPs were annotated as LDLRAD4, GPR180, and OR, enriching in growth factor receptor regulation pathways.ConclusionsWe present the first chromosome-level assembly of the Lion-head goose genome, which will expand the genomic resources of the Anatidae family, providing a basis for adaptation and evolution. Candidate genes significantly associated with different goose breeds may serve to understand the underlying mechanisms of weight differences.
Project description:Bar-headed geese (Anser indicus) are adaptable to plateau environments. In this study, we sequenced and assembled a high-quality chromosome-level genome of the bar-headed goose using PacBio long reads and Hi-C technique, and generated 115.73 Gb of Illumina short-reads and 95.89 Gb of PacBio long-reads. The assembled bar-headed goose genome, with a contig N50 of 5.734 Mb and a scaffold N50 of 65.77 Mb, is 1.129 Gb in length and includes 33 chromosomes and 451 fragments. BUSCO assessment yielded a completeness score of 94.4%. In total, 15,376 protein-coding genes were predicted, of which 94.95% had homologs in protein databases. We identified 78 positively selected genes (PSGs) in the bar-headed goose genome, which were mainly enriched in calcium ion and ATP-binding. This bar-headed goose genome will be an important resource for increasing our understanding regarding the genetic basis of adaptation to life at a high altitude.
Project description:BACKGROUND: Theories of ageing predict a trade-off between metabolism, reproduction, and maintenance. Species with low investment in early reproduction are thus expected to be able to evolve more efficient maintenance and repair mechanisms, allowing for a longer potential life span (intrinsic longevity). The erosion of telomeres, the protective caps at the ends of linear chromosomes, plays an important role in cellular and organismal senescence, signalling the onset of age-related disease due to accumulation of unrepaired somatic damage. Using extensive longitudinal data from a long-term study of a natural population of barnacle geese Branta leucopsis, we investigated individual rates of telomere length changes over two years in 34 birds between 0 and 22 years of age, covering almost 80% of the species' lifespan. RESULTS: We show that telomeres in this long-lived bird are very well maintained, as theoretically expected, with an average loss rate of only 5 base pairs per year among adults. We thus found no significant relationship between change in telomere length and age. However, telomeres tended to shorten at a faster pace in juveniles compared to adults. For the first time, we demonstrate a faster telomere attrition rate in females compared to males. We found no correlation between telomere loss rate and adult survival or change in body mass. CONCLUSIONS: Our results add further support for a link between longevity and telomere maintenance, and highlight the complexities of telomere dynamics in natural populations.
Project description:BackgroundThe bar-headed goose (Anser indicus) mainly inhabits the plateau wetlands of Asia. As a specialized high-altitude species, bar-headed geese can migrate between South and Central Asia and annually fly twice over the Himalayan mountains along the central Asian flyway. The physiological, biochemical and behavioral adaptations of bar-headed geese to high-altitude living and flying have raised much interest. However, to date, there is still no genome assembly information publicly available for bar-headed geese.MethodsIn this study, we present the first de novo whole genome sequencing and assembly of the bar-headed goose, along with gene prediction and annotation.Results10X Genomics sequencing produced a total of 124 Gb sequencing data, which can cover the estimated genome size of bar-headed goose for 103 times (average coverage). The genome assembly comprised 10,528 scaffolds, with a total length of 1.143 Gb and a scaffold N50 of 10.09 Mb. Annotation of the bar-headed goose genome assembly identified a total of 102 Mb (8.9%) of repetitive sequences, 16,428 protein-coding genes, and 282 tRNAs. In total, we determined that there were 63 expanded and 20 contracted gene families in the bar-headed goose compared with the other 15 vertebrates. We also performed a positive selection analysis between the bar-headed goose and the closely related low-altitude goose, swan goose (Anser cygnoides), to uncover its genetic adaptations to the Qinghai-Tibetan Plateau.ConclusionWe reported the currently most complete genome sequence of the bar-headed goose. Our assembly will provide a valuable resource to enhance further studies of the gene functions of bar-headed goose. The data will also be valuable for facilitating studies of the evolution, population genetics and high-altitude adaptations of the bar-headed geese at the genomic level.
Project description:BACKGROUND:The domestic goose is an economically important and scientifically valuable waterfowl; however, a lack of high-quality genomic data has hindered research concerning its genome, genetics, and breeding. As domestic geese breeds derive from both the swan goose (Anser cygnoides) and the graylag goose (Anser anser), we selected a female Tianfu goose for genome sequencing. We generated a chromosome-level goose genome assembly by adopting a hybrid de novo assembly approach that combined Pacific Biosciences single-molecule real-time sequencing, high-throughput chromatin conformation capture mapping, and Illumina short-read sequencing. FINDINGS:We generated a 1.11-Gb goose genome with contig and scaffold N50 values of 1.85 and 33.12 Mb, respectively. The assembly contains 39 pseudo-chromosomes (2n = 78) accounting for ?88.36% of the goose genome. Compared with previous goose assemblies, our assembly has more continuity, completeness, and accuracy; the annotation of core eukaryotic genes and universal single-copy orthologs has also been improved. We have identified 17,568 protein-coding genes and a repeat content of 8.67% (96.57 Mb) in this genome assembly. We also explored the spatial organization of chromatin and gene expression in the goose liver tissues, in terms of inter-pseudo-chromosomal interaction patterns, compartments, topologically associating domains, and promoter-enhancer interactions. CONCLUSIONS:We present the first chromosome-level assembly of the goose genome. This will be a valuable resource for future genetic and genomic studies on geese.