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Have no fear, the numbat is here! Today we announce the release of the first chromosome-length genome assembly for one of Australia’s most prized native marsupials.


Australian numbat (Myrmecobius fasciatus) boasts a beautifully coloured reddish-brown fur coat, laced with white stripes that contrast with the salt and pepper fur presiding from their tail to slightly past their rear feet. Glossy black eyes located in front of their two cupped ears are tied together with the numbat’s perfectly pointed black noise, making for an intriguing yet eye catching complexion. With their dazzling looks it’s easy to see why numbats are one of Australia’s most prized possessions.

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Photo Description: Numbat (Myrmecobius fasciatus). Photo credits: Perth Zoo, CC BY-SA 3.0, via Creative Commons

Numbats can be found in most of the 'lower half' of Australia. They are known to be solitary and territorial, occupying up to 1.5 square kilometres of land per individual, for same-sex animals. It’s common for male and female territories to overlap, and the two sexes may move even closer together during their mating season lasting from February to March.


Originating from the Dasyuromorphia, the order comprising most of the Australian carnivorous marsupials, these cute creatures feast exclusively on termites. Fussy eaters you might say! Consuming up to 20 000 per day, numbats are strictly diurnal, which means they are only active during the day and their activity levels are closely linked to those of termites [3].


The numbat was on the verge of extinction during the late 20th century. Extensive conservation efforts as well as government and community intervention led to a gradually increasing population of numbats. Still, with less than 1000 numbats left in the wild, the species is listed as ‘endangered’ on the Red List of the International Union for the Conservation of Nature and Natural Resources. The main threat to numbats is predation by introduced predators – foxes and cats. This threat of predation is exacerbated by other factors including habitat loss and fragmentation from land clearing, which also makes numbats more vulnerable to birds of prey such as wedge-tailed eagles and falcons.


The genome assembly shared today was generated using the sample provided by Perth Zoo which was used to generate a draft assembly with short-insert size Illumina reads [404,932,803 PE reads] and scaffolded to a chromosome-length genome with Hi-C [662,932,607 PE reads]. See our Methods page for more detail on the assembly procedure. Check the interactive map of the 7 numbat chromosomes below!

The termite-eating numbat is one of the thylacine’s closest living relatives, sharing a common ancestor ~35 million years ago. Both these enigmatic creatures have stripes, but that’s not where the similarity ends – as much as 95 per cent of their DNA may be identical [1].

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Check out below how the chromosomes in the new assembly align with those of another close relative of the thylacine, the Tasmanian devil. It appears that the chromosomes have been very stable across Dasyuromorphia, with both species exhibiting the 2n=14 karyotype and one-to-one correspondence between the chromosomes, with just a few tentative inversions.

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Whole genome alignment plot between the Numbat and the Tasmanian devil. Numbat genome assembly: Myrmecobius_fasciatus_HiC, Tasmanian devil genome assembly: Devil_ref_v7.0_HiC, a DNA Zoo upgrade from (Murchison et al., 2012).

This work was enabled by resources provided by DNA Zoo Australia, The University of Western Australia (UWA) and DNA Zoo, Aiden Lab at Baylor College of Medicine (BCM) with additional computational resources and support from the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.

 
 
 

Hey everyone! With the latest release we've hit the 275 assemblies mark, which means it's time to do some raw sequencing data upload to NCBI Sequence Read Archive!


The new data have now been uploaded under BioProject accession PRJNA512907, with legume data from a recently published paper available under BioProject accession PRJNA679437. Overall, the uploaded data cover Hi-C data for 281 species and WGS data for 91 spanning 569 experiments and 34,565,252,649,062 bases!


We thank Illumina, Macrogen, Novogen, the Broad Institute and Baylor College of Medicine GARP core for their help with the data production!


As always, we share the data without restrictions: see our data usage policy here.


Subscribe below or follow us on twitter for more upcoming updates!


P.S.: Check out the celebratory card from a junior DNA Zoo Australia member marking the occasion, below!

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Updated: Feb 23, 2022

Just about everyone knows what a watermelon (Citrullus lanatus) looks like. They come in various sizes and shapes, and the edible interior portion in various colors (white, red, yellow, etc.), but, how many are familiar with the ancestors of the watermelon - the primitive, wild forms?

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Immature fruit of Citrullus naudinianus, photo by Robert Jarret (USDA) [CC]

The genus Citrullus is small in terms of the number of recognized species – containing only 7 or so. All the members of the genus are native to xerophytic (containing little liquid water) environments and the distribution ranges of individual species includes portions of the African continent, the Middle East and South and Central Asia. Each Citrullus species possesses one or more unique characteristics that allow it to survive, and thrive, in a hostile environment.


A great example of the diversity within the genus Citrullus is the gemsbok cucumber (it’s not really a cucumber at all!). The fruit of this desert-loving plant (scientific name Citrullus naudinianus) are, in fact, eaten by gemsbok. However, the fruit are also favored by mole-rats, jackals and honey badgers. Squirrels, porcupines, crickets and other insects use the water that gathers in the skin of old fruit after rains.


The fruit of the gemsbok cucumber are bitter. This is likely due to the presence of tetracyclic terpines common in the fruit of some other members of the genus. Nonetheless, the cooked fruit are edible. The bushmen of the Kalahari eat the fruit after they have been roasted in a fire or boiled. The cooking renders the terpines harmless. The fleshy fruits are also known to serve as a source of water and have even been used to make pickles. In addition to its fleshy fruits, the gemsbok cucumber produces large underground storage roots.

We report here a chromosome-length genome sequence of the gemsbok cucumber (Citrullus naudinianus), a plant bearing small (6-12cm in length) oval-shaped fruits with rudimentary spines. This plant is native to southern Africa including Botswana, Namibia, Mozambique, Zambia, Zimbabwe and South Africa. It represents the basal branch in the taxonomic tree of Citrullus and the Citrullus species most distantly related to the common watermelon. Unlike all other members of the genus Citrullus, the gemsbok cucumber is dioecious having separate male and female plants. The genetic mechanism accounting for the conversion from dioecy (gemsbok cucumber) to monoecy (all other Citrullus species), has yet to be determined.


The genome sequence of the gemsbok cucumber serves to provide an evolutionary anchor point for a pan-genus study on genome evolution in the genus Citrullus. It also facilitates an examination of the evolution of the gemsbok cucumber’s many unique adaptive traits that allow it to survive in an environment where few other plants can.

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Interior of ripening fruit of Citrullus naudinianus, photo by Robert Jarret, USDA [CC]

Check the interactive map below and explore the Hi-C contacts across the 11 chromosomes of the gemsbok cucumber, and don't forget to visit the assembly page for more details on this HiFi+Hi-C genome assembly!

References:

1. Chomicki, G. and S. Renner. 2015. Watermelon origin solved with molecular phylogenetics including Linnaean material: another example of museomics. New Phytologist (2015) 205: 526–532 doi: 10.1111/nph.13163.

2. Jeffrey, C. 1978. Cucurbitaceae. Fl. Zambes. 4:414-499. Flora Zambesiaca Managing Committee, Glasgow.

3. Retief, E. and N.L. Meyer. 2017. Cucurbitaceae. In: E. Retief and N.L. Meyer (Eds.) Plants of the Free State: Inventory and identification guide. Strelitzia 38:484-489. South African National Biodiversity Institute, Pretoria.

4. Schaefer, H. and S.S. Renner. 2011. Cucurbitaceae. Cucurbitaceae Durande (1782), nom. cons. In: K. Kubitzk (ed.) Flowering Plants. Eudicots: Sapindales, Cucurbitales, Myrtaceae. Springer. pp. 112-174.

5. Tropical Plants Database, Ken Fern. tropical.theferns.info. 2021-12-26. <tropical.theferns.info/viewtropical.php?id=Acanthosicyos+naudinianus>

6. WFO. 2021: Acanthosicyos naudinianus (Sond.) C. Jeffrey. Published on the internet; http://www.worldfloraonline.org/taxon/wfo-000051376.

 
 
 

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