The first Antechinus reference genome provides a resource for investigating the genetic basis of semelparity and age-related neuropathologies

Antechinus are a genus of mouse-like marsupials that exhibit a rare reproductive strategy known as semelparity and also naturally develop age-related neuropathologies similar to those in humans. We provide the first annotated antechinus reference genome for the brown antechinus (Antechinus stuartii). The reference genome is 3.3 Gb in size with a scaffold N50 of 73Mb and 93.3% complete mammalian BUSCOs. Using bioinformatic methods we assign scaffolds to chromosomes and identify 0.78 Mb of Y-chromosome scaffolds. Comparative genomics revealed interesting expansions in the NMRK2 gene and the protocadherin gamma family, which have previously been associated with aging and age-related dementias respectively. Transcriptome data displayed expression of common Alzheimer’s related genes in the antechinus brain and highlight the potential of utilising the antechinus as a future disease model. The valuable genomic resources provided herein will enable future research to explore the genetic basis of semelparity and age-related processes in the antechinus.

The first Antechinus reference genome provides a resource for investigating the genetic basis of semelparity and age-related neuropathologies

Antechinus are a genus of mouse-like marsupials that exhibit a rare reproductive strategy known as semelparity and also naturally develop age-related neuropathologies similar to those in humans. We provide the first annotated antechinus reference genome for the brown antechinus (Antechinus stuartii). The reference genome is 3.3Gb in size with a scaffold N50 of 73Mb and 93.3% complete mammalian BUSCOs. Using bioinformatic methods we assign scaffolds to chromosomes and identify 0.78Mb of Y-chromosome scaffolds. Comparative genomics revealed interesting expansions in the NMRK2 gene and the protocadherin gamma family, which have previously been associated with aging and age-related dementias respectively. Transcriptome data displayed expression of common Alzheimer’s related genes in the antechinus brain and highlight the potential of utilising the antechinus as a future disease model. The valuable genomic resources provided herein will enable future research to explore the genetic basis of semelparity and age-related processes in the antechinus.

Responding to the weather: energy budgeting by a small mammal in the wild

Energy conservation is paramount for small mammals because of their small size, large surface area to volume ratio, and the resultant high heat loss to the environment. To survive on limited food resources and to fuel their expensive metabolism during activity, many small mammals employ daily torpor to reduce energy expenditure during the rest phase. We hypothesized that a small terrestrial semelparous marsupial, the brown antechinus Antechinus stuartii, would maximize activity when foraging conditions were favorable to gain fat reserves before their intense breeding period, but would increase torpor use when conditions were poor to conserve these fat reserves. Female antechinus were trapped and implanted with small temperature-sensitive radio transmitters to record body temperature and to quantify torpor expression and activity patterns in the wild. Most antechinus used torpor at least once per day over the entire study period. Total daily torpor use increased and mean daily body temperature decreased significantly with a reduction in minimum ambient temperature. Interestingly, antechinus employed less torpor on days with more rain and decreasing barometric pressure. In contrast to torpor expression, activity was directly related to ambient temperature and inversely related to barometric pressure. Our results reveal that antechinus use a flexible combination of physiology and behavior that can be adjusted to manage their energy budget according to weather variables.

Movement of small mammals through a road-underpass is facilitated by a wildlife railing

Wildlife underpasses in Australia are commonly fitted with timber railings to facilitate the passage of arboreal and scansorial mammals but there are no published accounts of railing use. We compared detections of such mammals on railings in two underpasses to detections on the ground in these and other underpasses. The brown antechinus (Antechinus stuartii) and the black rat (Rattus rattus) were detected on a closely monitored railing on 12–14% of nights over three years. These species were detected on the ground of underpasses on <1% of nights. Koalas (Phascolarctos cinereus) and brushtail possums (Trichosurus spp.) were infrequently detected, koalas only on the ground and brushtail possums mostly on the ground. These observations suggest that road crossings by small scansorial mammals can be facilitated by timber railings.

Post-fire recovery of torpor and activity patterns of a small mammal

To cope with the post-fire challenges of decreased availability of food and shelter, brown antechinus ( Antechinus stuartii ), a small marsupial mammal, increase the use of energy-conserving torpor and reduce activity. However, it is not known how long it takes for animals to resume pre-fire torpor and activity patterns during the recovery of burnt habitat. Therefore, we tested the hypothesis that antechinus will adjust torpor use and activity after a fire depending on vegetation recovery. We simultaneously quantified torpor and activity patterns for female antechinus from three adjacent areas: (i) the area of a management burn 1 year post-fire, (ii) an area that was burned 2 years prior, and (iii) a control area. In comparison to shortly after the management burn, antechinus in all three groups displayed less frequent and less pronounced torpor while being more active. We provide the first evidence that only 1 year post-fire antechinus resume pre-fire torpor and activity patterns, probably in response to the return of herbaceous ground cover and foraging opportunities.

Reproductive parameters of surviving 'die-off' male Antechinus flavipes and Antechinus stuartii (Dasyuridae : Marsupialia) in their second year of life

Males of the genus Antechinus (Dasyuromorphia) undergo dramatic behavioural, physical and physiological change that results in complete male mortality after the mating period. Occasionally, males in the wild survive longer than this immediate post-mating period, and post ‘die-off’ survivorship for a second year has also been documented in captivity. The present study sought to quantify changes in the physiology and behaviour of male A. flavipes and A. stuartii that survive through a second year of life. Males from both species never demonstrated spermatorrhoea in their second year, although secondary sexual characteristics and sexual behaviour were recovered in their second year. Thus, the seminiferous tubular collapse seen before the mating period in their first year of life is irreversible and complete, although the cycling of other sexual characteristics suggests that the hypothalamic-pituitary-gonadal pathways and function of the interstitial cells of the testes are retrievable.