Menu
April 21, 2020  |  

Genome analysis of the rice coral Montipora capitata.

Corals comprise a biomineralizing cnidarian, dinoflagellate algal symbionts, and associated microbiome of prokaryotes and viruses. Ongoing efforts to conserve coral reefs by identifying the major stress response pathways and thereby laying the foundation to select resistant genotypes rely on a robust genomic foundation. Here we generated and analyzed a high quality long-read based ~886 Mbp nuclear genome assembly and transcriptome data from the dominant rice coral, Montipora capitata from Hawai’i. Our work provides insights into the architecture of coral genomes and shows how they differ in size and gene inventory, putatively due to population size variation. We describe a recent example of foreign gene acquisition via a bacterial gene transfer agent and illustrate the major pathways of stress response that can be used to predict regulatory components of the transcriptional networks in M. capitata. These genomic resources provide insights into the adaptive potential of these sessile, long-lived species in both natural and human influenced environments and facilitate functional and population genomic studies aimed at Hawaiian reef restoration and conservation.


September 22, 2019  |  

The Florida manatee (Trichechus manatus latirostris) immunoglobulin heavy chain suggests the importance of clan III variable segments in repertoire diversity.

Manatees are a vulnerable, charismatic sentinel species from the evolutionarily divergent Afrotheria. Manatee health and resistance to infectious disease is of great concern to conservation groups, but little is known about their immune system. To develop manatee-specific tools for monitoring health, we first must have a general knowledge of how the immunoglobulin heavy (IgH) chain locus is organized and transcriptionally expressed. Using the genomic scaffolds of the Florida manatee (Trichechus manatus latirostris), we characterized the potential IgH segmental diversity and constant region isotypic diversity and performed the first Afrotherian repertoire analysis. The Florida manatee has low V(D)J combinatorial diversity (3744 potential combinations) and few constant region isotypes. They also lack clan III V segments, which may have caused reduced VH segment numbers. However, we found productive somatic hypermutation concentrated in the complementarity determining regions. In conclusion, manatees have limited IGHV clan and combinatorial diversity. This suggests that clan III V segments are essential for maintaining IgH locus diversity. Copyright © 2017 Elsevier Ltd. All rights reserved.


September 22, 2019  |  

Transcription-associated mutation promotes RNA complexity in highly expressed genes – A major new source of selectable variation.

Alternatively spliced transcript isoforms are thought to play a critical role for functional diversity. However, the mechanism generating the enormous diversity of spliced transcript isoforms remains unknown, and its biological significance remains unclear. We analyzed transcriptomes in saker falcons, chickens, and mice to show that alternative splicing occurs more frequently, yielding more isoforms, in highly expressed genes. We focused on hemoglobin in the falcon, the most abundantly expressed genes in blood, finding that alternative splicing produces 10-fold more isoforms than expected from the number of splice junctions in the genome. These isoforms were produced mainly by alternative use of de novo splice sites generated by transcription-associated mutation (TAM), not by the RNA editing mechanism normally invoked. We found that high expression of globin genes increases mutation frequencies during transcription, especially on nontranscribed DNA strands. After DNA replication, transcribed strands inherit these somatic mutations, creating de novo splice sites, and generating multiple distinct isoforms in the cell clone. Bisulfate sequencing revealed that DNA methylation may counteract this process by suppressing TAM, suggesting DNA methylation can spatially regulate RNA complexity. RNA profiling showed that falcons living on the high Qinghai-Tibetan Plateau possess greater global gene expression levels and higher diversity of mean to high abundance isoforms (reads per kilobases per million mapped reads?=18) than their low-altitude counterparts, and we speculate that this may enhance their oxygen transport capacity under low-oxygen environments. Thus, TAM-induced RNA diversity may be physiologically significant, providing an alternative strategy in lifestyle evolution.


September 22, 2019  |  

Genomes of 13 domesticated and wild rice relatives highlight genetic conservation, turnover and innovation across the genus Oryza.

The genus Oryza is a model system for the study of molecular evolution over time scales ranging from a few thousand to 15 million years. Using 13 reference genomes spanning the Oryza species tree, we show that despite few large-scale chromosomal rearrangements rapid species diversification is mirrored by lineage-specific emergence and turnover of many novel elements, including transposons, and potential new coding and noncoding genes. Our study resolves controversial areas of the Oryza phylogeny, showing a complex history of introgression among different chromosomes in the young ‘AA’ subclade containing the two domesticated species. This study highlights the prevalence of functionally coupled disease resistance genes and identifies many new haplotypes of potential use for future crop protection. Finally, this study marks a milestone in modern rice research with the release of a complete long-read assembly of IR 8 ‘Miracle Rice’, which relieved famine and drove the Green Revolution in Asia 50 years ago.


September 22, 2019  |  

Draft genome assembly of the invasive cane toad, Rhinella marina.

The cane toad (Rhinella marina formerly Bufo marinus) is a species native to Central and South America that has spread across many regions of the globe. Cane toads are known for their rapid adaptation and deleterious impacts on native fauna in invaded regions. However, despite an iconic status, there are major gaps in our understanding of cane toad genetics. The availability of a genome would help to close these gaps and accelerate cane toad research.We report a draft genome assembly for R. marina, the first of its kind for the Bufonidae family. We used a combination of long-read Pacific Biosciences RS II and short-read Illumina HiSeq X sequencing to generate 359.5 Gb of raw sequence data. The final hybrid assembly of 31,392 scaffolds was 2.55 Gb in length with a scaffold N50 of 168 kb. BUSCO analysis revealed that the assembly included full length or partial fragments of 90.6% of tetrapod universal single-copy orthologs (n = 3950), illustrating that the gene-containing regions have been well assembled. Annotation predicted 25,846 protein coding genes with similarity to known proteins in Swiss-Prot. Repeat sequences were estimated to account for 63.9% of the assembly.The R. marina draft genome assembly will be an invaluable resource that can be used to further probe the biology of this invasive species. Future analysis of the genome will provide insights into cane toad evolution and enrich our understanding of their interplay with the ecosystem at large.


September 22, 2019  |  

First draft genome for red sea bream of family Sparidae.

Reference genomes for all organisms on earth are now attainable owing to advances in genome sequencing technologies (Goodwin et al., 2016). Generally, species that contribute considerably to the economy or human welfare are sequenced and are considered more important than others. Furthermore, coastal indigenous people mainly depend on marine species for their food sources, which has resulted in the extinction of several marine species (Cisneros-Montemayor et al., 2016). Of these, an extinction risk assessment of marine fishes, mainly for sea breams (Family: Sparidae), has recently been conducted by way of a global extinction risk assessment from the dataset of the International Union for Conservation of Nature’s Red List Process, which mentions that around 25 species are threatened/near-threatened according to their body weight (Comeros-Raynal et al., 2016). Another report clearly showed the benefit of worldwide aquaculture production, which contributed to 47% of total seafood production, and also highlighted the over-fishing of sea breams (FAO, 2018). The Republic of Korea is the fourth largest seafood producer in the world, producing 3.3 million tons in 2015 and exporting seafood worth $1.6 billion in 2016; therefore, aquaculture- associated research is fundamental for Korea. In the present study, the red sea bream (Pagrus major), which belongs to the family Sparidae, which comprises 35 genera, 132 species, and 10 subspecies (de la Herran et al., 2001; NCBI, 2018), was assessed.


July 19, 2019  |  

Bats may eat diurnal flies that rest on wind turbines

Bats are currently killed in large numbers at wind turbines worldwide, but the ultimate reason why this happens remains poorly understood. One hypothesis is that bats visit wind turbines to feed on insects exposed at the turbine towers. We used single molecule next generation DNA sequencing to identify stomach contents of 18 bats of four species (Pipistrellus pygmaeus, Nyctalus noctula, Eptesicus nilssonii and Vespertilio murinus) found dead under wind turbines in southern Sweden. Stomach contents were diverse but included typically diurnal flies, e.g. blow-flies (Calliphoridae), flesh-flies (Sarcophagidae) and houseflies (Muscidae) and also several flightless taxa. Such prey items were eaten by all bat species and at all wind turbine localities and it seems possible that they had been captured at or near the surface of the turbines at night. Using sticky traps, we documented an abundance of swarming (diurnal) ants (Myrmica spp.) and sometimes blow-flies and houseflies at the nacelle house. Near the base of the tower the catches were more diverse and corresponded better with the taxa found in the bat stomachs, including various diurnal flies. To evaluate if flies and other insects resting on the surface of a wind turbine are available to bats, we ensonified a house fly (Musca) on a smooth (plastic) surface with synthetic ultrasonic pulses of the frequencies used by the bat species that we had sampled. The experiment revealed potentially useful echoes, provided the attack angle was low and the frequency high (50–75 kHz). Hence resting flies and other arthropods can probably be detected by echolocating bats on the surface of a wind turbine. Our findings are consistent with published observations of the behavior of bats at wind turbines and may actually explain the function of some of these behaviors.


July 19, 2019  |  

Characterisation of MHC class I genes in the koala.

Koala (Phascolarctos cinereus) populations are on the decline across the majority of Australia’s mainland. Two major diseases threatening the long-term survival of affected koala populations are caused by obligate intracellular pathogens: Chlamydia and koala retrovirus (KoRV). To improve our understanding of the koala immune system, we characterised their major histocompatibility complex (MHC) class I genes, which are centrally involved in presenting foreign peptides derived from intracellular pathogens to cytotoxic T cells. A total of 11 class I genes were identified in the koala genome. Three genes, Phci-UA, UB and UC, showed relatively high genetic variability and were expressed in all 12 examined tissues, whereas the other eight genes had tissue-specific expression and limited polymorphism. Evidence of diversifying selection was detected in Phci-UA and UC, while gene conversion may have played a role in creating new alleles at Phci-UB. We propose that Phci-UA, UB and UC are likely classical MHC genes of koalas, and further research is needed to understand their role in koala chlamydial and KoRV infections.


July 19, 2019  |  

Long-read sequence assembly of the firefly Pyrocoelia pectoralis genome.

Fireflies are a family of insects within the beetle order Coleoptera, or winged beetles, and they are one of the most well-known and loved insect species because of their bioluminescence. However, the firefly is in danger of extinction because of the massive destruction of its living environment. In order to improve the understanding of fireflies and protect them effectively, we sequenced the whole genome of the terrestrial firefly Pyrocoelia pectoralis.Here, we developed a highly reliable genome resource for the terrestrial firefly Pyrocoelia pectoralis (E. Oliv., 1883; Coleoptera: Lampyridae) using single molecule real time (SMRT) sequencing on the PacBio Sequel platform. In total, 57.8 Gb of long reads were generated and assembled into a 760.4-Mb genome, which is close to the estimated genome size and covered 98.7% complete and 0.7% partial insect Benchmarking Universal Single-Copy Orthologs. The k-mer analysis showed that this genome is highly heterozygous. However, our long-read assembly demonstrates continuousness with a contig N50 length of 3.04 Mb and the longest contig length of 13.69 Mb. Furthermore, 135 589 SSRs and 341 Mb of repeat sequences were detected. A total of 23 092 genes were predicted; 88.44% of genes were annotated with one or more related functions.We assembled a high-quality firefly genome, which will not only provide insights into the conservation and biodiversity of fireflies, but also provide a wealth of information to study the mechanisms of their sexual communication, bio-luminescence, and evolution.© The Authors 2017. Published by Oxford University Press.


July 19, 2019  |  

Adaptation and conservation insights from the koala genome.

The koala, the only extant species of the marsupial family Phascolarctidae, is classified as ‘vulnerable’ due to habitat loss and widespread disease. We sequenced the koala genome, producing a complete and contiguous marsupial reference genome, including centromeres. We reveal that the koala’s ability to detoxify eucalypt foliage may be due to expansions within a cytochrome P450 gene family, and its ability to smell, taste and moderate ingestion of plant secondary metabolites may be due to expansions in the vomeronasal and taste receptors. We characterized novel lactation proteins that protect young in the pouch and annotated immune genes important for response to chlamydial disease. Historical demography showed a substantial population crash coincident with the decline of Australian megafauna, while contemporary populations had biogeographic boundaries and increased inbreeding in populations affected by historic translocations. We identified genetically diverse populations that require habitat corridors and instituting of translocation programs to aid the koala’s survival in the wild.


July 19, 2019  |  

A high-quality, long-read de novo genome assembly to aid conservation of Hawaii’s last remaining crow species

Genome-level data can provide researchers with unprecedented precision to examine the causes and genetic consequences of population declines, which can inform conservation management. Here, we present a high-quality, long-read, de novo genome assembly for one of the world’s most endangered bird species, the ?Alala (Corvus hawaiiensis; Hawaiian crow). As the only remaining native crow species in Hawai?i, the ?Alala survived solely in a captive-breeding program from 2002 until 2016, at which point a long-term reintroduction program was initiated. The high-quality genome assembly was generated to lay the foundation for both comparative genomics studies and the development of population-level genomic tools that will aid conservation and recovery efforts. We illustrate how the quality of this assembly places it amongst the very best avian genomes assembled to date, comparable to intensively studied model systems. We describe the genome architecture in terms of repetitive elements and runs of homozygosity, and we show that compared with more outbred species, the ?Alala genome is substantially more homozygous. We also provide annotations for a subset of immunity genes that are likely to be important in conservation management, and we discuss how this genome is currently being used as a roadmap for downstream conservation applications.


July 7, 2019  |  

It’s more than stamp collecting: how genome sequencing can unify biological research.

The availability of reference genome sequences, especially the human reference, has revolutionized the study of biology. However, while the genomes of some species have been fully sequenced, a wide range of biological problems still cannot be effectively studied for lack of genome sequence information. Here, I identify neglected areas of biology and describe how both targeted species sequencing and more broad taxonomic surveys of the tree of life can address important biological questions. I enumerate the significant benefits that would accrue from sequencing a broader range of taxa, as well as discuss the technical advances in sequencing and assembly methods that would allow for wide-ranging application of whole-genome analysis. Finally, I suggest that in addition to ‘big science’ survey initiatives to sequence the tree of life, a modified infrastructure-funding paradigm would better support reference genome sequence generation for research communities most in need. Copyright © 2015 Elsevier Ltd. All rights reserved.


July 7, 2019  |  

Twenty-one novel microsatellite loci for the endangered Florida salt marsh vole (Microtus pennsylvanicus dukecampbelli)

We present 21 microsatellite loci developed for Florida salt marsh voles (Microtus pennsylvanicus dukecampbelli). Microsatellites were identified from single molecule real time sequencing (Pacific Biosciences). We screened 30 loci and identified 21 loci as suitable for genotyping. We screened 17 individuals from Long Cabbage Key, and 3 individuals from an unnamed island. There was no significant departure from Hardy–Weinberg equilibrium or linkage equilibrium. Fifteen of the 21 loci were variable, with overall observed heterozygosity averaging 0.39, and a mean number of alleles of 3.14. Linkage disequilibrium estimate of Ne was 10.7 (95 % CI 6.1–20.1). These markers will be useful for conservation genetics studies of this endangered species.


July 7, 2019  |  

Novel urease-negative Helicobacter sp. ‘H. enhydrae sp. nov.’ isolated from inflamed gastric tissue of southern sea otters.

A total of 31 sea otters Enhydra lutris nereis found dead or moribund (and then euthanized) were necropsied in California, USA. Stomach biopsies were collected and transected with equal portions frozen or placed in formalin and analyzed histologically and screened for Helicobacter spp. in gastric tissue. Helicobacter spp. were isolated from 9 sea otters (29%); 58% (18 of 31) animals were positive for helicobacter by PCR. The Helicobacter sp. was catalase- and oxidase-positive and urease-negative. By electron microscopy, the Helicobacter sp. had lateral and polar sheathed flagella and had a slightly curved rod morphology. 16S and 23S rRNA sequence analyses of all ‘H. enhydrae’ isolates had similar sequences, which clustered as a novel Helicobacter sp. closely related to H. mustelae (96-97%). The genome sequence of isolate MIT 01-6242 was assembled into a single ~1.6 Mb long contig with a 40.8% G+C content. The annotated genome contained 1699 protein-coding sequences and 43 RNAs, including 65 genes homologous to known Helicobacter spp. and Campylobacter spp. virulence factors. Histological changes in the gastric tissues extended from mild cystic degeneration of gastric glands to severe mucosal erosions and ulcers. Silver stains of infected tissues demonstrated slightly curved bacterial rods at the periphery of the gastric ulcers and on the epithelial surface of glands. The underlying mucosa and submucosa were infiltrated by low numbers of neutrophils, macrophages, and lymphocytes, with occasional lymphoid aggregates and well-defined lymphoid follicles. This is the second novel Helicobacter sp., which we have named ‘H. enhydrae’, isolated from inflamed stomachs of mustelids, the first being H. mustelae from a ferret.


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.