Abstract
Cherax destructor, the yabby, is an iconic Australian freshwater crayfish species, which, similar to other major invertebrate groups, is grossly under-represented in genomic databases. The yabby is also the principal commercial freshwater crustacean species in Australia subject to explotation via inland fisheries and aquaculture. To address the genomics knowledge gap for this species and explore cost effective and efficient methods for genome assembly, we generated 106.8 gb of Nanopore reads and performed a long-read only assembly of the Cherax destructor genome. On a mini-server configured with an ultra-fast swap space, the de novo assembly took 131 h (∼5.5 days). Genome polishing with 126.3 gb of PCR-Free Illumina reads generated an assembled genome size of 3.3 gb (74.6% BUSCO completeness) with a contig N50 of 80,900 bp, making it the most contiguous for freshwater crayfish genome assemblies. We found an unusually large number of cellulase genes within the yabby genome which is relevant to understanding the nutritional biology, commercial feed development, and ecological role of this species and crayfish more generally. These resources will be useful for genomic research on freshwater crayfish and our methods for rapid and super-efficient genome assembly will have wide application.
Highlights
Australia’s freshwater crayfish are highly diverse and as charismatic as the country’s better known avian and mammalian fauna, but far less appreciated and studied
Given the degree of ongoing interest in the nutritional biology and trophic status of freshwater crayfish, we examine the diversity of cellulase genes in freshwater crayfish
Assuming the sequencing depth with the highest observed frequency represents the coverage of the single-copy genomic region, the genome size of Cherax destructor is estimated to be 4.36–4.64 gb (Total sequencing yield in gigabases divided by single-copy coverage)
Summary
Australia’s freshwater crayfish are highly diverse and as charismatic as the country’s better known avian and mammalian fauna, but far less appreciated and studied. Crayfish are found in a range of freshwater environments, include some exceptionally large species in Australia, and can reach very high densities in both natural and cultured environments (Nyström and Strand, 1996; Whitledge and Rabeni, 1997; Jones and Ruscoe, 2000; Reynolds and Richardson, 2013). As a result, they often represent keystone species and ecosystem engineers in permanent and semi-permanent freshwater systems in many parts of the world. Given the degree of ongoing interest in the nutritional biology and trophic status of freshwater crayfish, we examine the diversity of cellulase genes in freshwater crayfish
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
