Natalie Warburton

Poor numeracy/quantitative skills (QS) development is a widespread issue across Australian tertiary education. Lack of fundamental QS can impede students' progression in STEM degrees, and disadvantage individual students across other domains of life (e.g., financial literacy and active citizenship). Our ACDS-funded Diversity in Numbers (DiN) project seeks to evaluate a targeted, course-wide, just-in-time model for undergraduate development of QS. Digital numeracy modules will be designed to scaffold QS development through embedded interactive content and rich automated feedback. Each module targets a core QS concept (e.g., statistical testing, unit conversions, mathematical relationships) and is framed around a published article relevant to unit content, to expand student awareness of numbers as a tool across diverse fields of science. Given the ongoing under-representation of women, LGBTIQA+ people and other minorities in STEM, the selection of journal articles aims to increase students' appreciation of diversity from many different viewpoints, while developing their QS. At a broader level, the project aims to address the ongoing lack of diversity among STEM graduates and within the STEM workforce by enabling students to "see themselves" within published research. Here we will present the design of our research project to assess the success of our pilot DiN modules.

Bandicoots and bilbies (order Peramelemorphia) represent the principle group of omnivorous marsupials from a range of habitats across Australia and New Guinea. Bandicoots and bilbies most commonly use quadrupedal, asymmetrical half-bounding or bounding gaits and present an unusual assortment of hind limb morphological features, including an ossified patella, a modified tibiofibular joint, and syndactylous morphology of the pes. Comparative dissections of the hind limb of the southern brown bandicoot Isoodon obesulus fusciventer (n = 8) and greater bilby Macrotis lagotis (n=4) provide an interesting study in the adaptation of soft-tissues in the Peramelemorphia. Bilby hind limb muscle anatomy appeared relatively unspecialised; the arrangement and development of muscles was as expected for a syndactylous marsupial with moderately long, slender limb bones, a semi-flexed stance and an unspecialised digitigrade gait. In contrast, I. obesulus displayed significant modification of the muscular anatomy and associated connective tissues of the hind limb, which appear to reflect adaptation for rapid acceleration and locomotion, including strongly flexed limb posture, long muscle bellies with very short tendons, and extreme development of fascial structures. Differences between the hind limb anatomy of the bandicoot and bilby appear likely to reflect the different ecological and environmental pressures on their locomotor strategy. On one hand, bilbies inhabit open, arid country and retreat a relatively short distance to the shelter of their burrow when threatened. On the other hand, southern brown bandicoots inhabit much more closed environments and use explosive acceleration through dense cover to flee from potential threats.

Purpose: The somatic neuromuscular junction (NMJ) is a valuable experimental model of synapse formation. Such experiments are most commonly performed on placental mammals (e.g. mouse), where all four limbs develop on a similar timescale. By contrast, some Australian marsupials have very segmented limb development, where forelimbs are precociously developed to assist the journey to the pouch, while hindlimbs are comparatively unformed. We have compared the morphological development of the NMJ in kangaroo hindlimbs and forelimbs, to investigate how NMJ development proceeds in an animal with this novel developmental pattern. Methods: Three Western Grey Kangaroo neonates aged postnatal day (P) 0, 26 and 100 were ethically sourced from licensed shooters in South-Western Australia. 5 forelimb and 4 hindlimb muscles from each specimen were embedded, cryosectioned, and stained immunohistochemically for NMJ compartment proteins. Results: Confocal micrographs of adult kangaroo NMJs revealed an unusual oval endplate with a internal perforation at its centre. When markers of NMJ development described in rodents (e.g. neurofilament distribution, ACh receptor clustering) were analysed in P0 neonates, forelimb NMJs were considerably more developed than hindlimb junctions. However, between P0 and 100, NMJs in kangaroo forelimbs developed at a slower rate than hindlimb NMJs, so that all limbs were similarly developed by P100. Conclusions: Our preliminary data indicates that the segmented limb development in Western Grey Kangaroos is reflected at the level of the NMJ. This segmented NMJ development, combined with the relative accessibility of kangaroo neonates (which undergo a large degree of maturation in the pouch), present novel opportunities for studying synaptic development compared with placental mammals.

The principles of synapse formation have been largely unraveled by investigations at the somatic neuromuscular junction (NMJ). Such experiments are commonly performed on placental mammals (e.g. mouse), where all four limbs develop on a similar timescale. By contrast, some Australian marsupials have very segmented limb development, where forelimbs are precociously developed to assist the journey to the pouch, while hindlimbs are comparatively unformed. We explored the implications of this novel developmental pattern for the morphological development of marsupial NMJs. Western Grey Kangaroo neonates (n = 8) aged postnatal day (P) 0-100 were ethically sourced from licensed shooters. Multiple (5-9) muscles from each specimen were embedded, cryosectioned, and stained immunohistochemically for NMJ compartment proteins. Confocal micrographs of adult kangaroo NMJs revealed small oval endplates with a central internal perforation. Standard indices of synapse maturation (e.g. ACh receptor clustering) confirmed significant NMJ development from P0-P100. Notably, forelimb NMJs were considerably more developed than hindlimb junctions at P0. From P0-100, kangaroo forelimb NMJs developed at a slower rate than hindlimb NMJs, so that all limbs were similarly developed by P100. Interestingly, within the hindlimb, a detailed comparison of 5 muscles suggested a single, homogenous developmental profile, in contrast with recent studies in mouse suggesting both fast and delayed synapsing muscle populations (Pun et al., 2002). The segmented nature of NMJ development in Western Grey Kangaroos combined with the relative accessibility provided by a protracted maturation in the pouch, suggest that marsupials may present novel opportunities for studying synapse maturation compared with placental mammals.