Australian Populations Research Articles

Multiple Recent Colonizations of the Australian Region by the Chydorus sphaericus Group (Crustacea: Cladocera)

Biotic introductions are an ongoing disruption for many ecosystems. For passively dispersed freshwater zooplankton, transcontinental introductions have been common but are poorly studied in the southern hemisphere. Here we assess the hypothesis of recent introduction for populations of the Chydorus sphaericus group (Crustacea: Cladocera) in Australia. We analyzed 254 sequences (63 original sequences) from the cytochrome oxidase I region of mitochondrial DNA of Chydorus sp., which included global representation. Three Australian populations were connected with separate clades in the northern hemisphere, suggesting multiple colonization events for Australia. The timescale of the divergences was consistent with recent (Quaternary) dispersal. As Australian populations are exposed to migrating birds from the northern hemisphere, both avian and anthropogenic sources are candidates for dispersal vectors. We concluded that recent cross-hemisphere dispersal in the Chydorus sphaericus group is more common than previously believed.

The genomic structure of isolation across breed, country and strain for important South African and Australian sheep populations

BackgroundSouth Africa and Australia shares multiple important sheep breeds. For some of these breeds, genomic breeding values are provided to breeders in Australia, but not yet in South Africa. Combining genomic resources could facilitate development for across country selection, but the influence of population structures could be important to the compatability of genomic data from varying origins. The genetic structure within and across breeds, countries and strains was evaluated in this study by population genomic parameters derived from SNP-marker data. Populations were first analysed by breed and country of origin and then by subpopulations of South African and Australian Merinos.ResultsMean estimated relatedness according to the genomic relationship matrix varied by breed (-0.11 to 0.16) and bloodline (-0.08 to 0.06) groups and depended on co-ancestry as well as recent genetic links. Measures of divergence across bloodlines (FST: 0.04–0.12) were sometimes more distant than across some breeds (FST: 0.05–0.24), but the divergence of common breeds from their across-country equivalents was weak (FST: 0.01–0.04). According to mean relatedness, FST, PCA and Admixture, the Australian Ultrafine line was better connected to the SA Cradock Fine Wool flock than with other AUS bloodlines. Levels of linkage disequilibrium (LD) between adjacent markers was generally low, but also varied across breeds (r2: 0.14–0.22) as well as bloodlines (r2: 0.15–0.19). Patterns of LD decay was also unique to breeds, but bloodlines differed only at the absolute level. Estimates of effective population size (Ne) showed genetic diversity to be high for the majority of breeds (Ne: 128–418) but also for bloodlines (Ne: 137–369).ConclusionsThis study reinforced the genetic complexity and diversity of important sheep breeds, especially the Merino breed. The results also showed that implications of isolation can be highly variable and extended beyond breed structures. However, knowledge of useful links across these population substructures allows for a fine-tuned approach in the combination of genomic resources. Isolation across country rarely proved restricting compared to other structures considered. Consequently, research into the accuracy of across-country genomic prediction is recommended.

Revealing mechanisms of infectious disease spread through empirical contact networks.

The spread of pathogens fundamentally depends on the underlying contacts between individuals. Modeling the dynamics of infectious disease spread through contact networks, however, can be challenging due to limited knowledge of how an infectious disease spreads and its transmission rate. We developed a novel statistical tool, INoDS (Identifying contact Networks of infectious Disease Spread) that estimates the transmission rate of an infectious disease outbreak, establishes epidemiological relevance of a contact network in explaining the observed pattern of infectious disease spread and enables model comparison between different contact network hypotheses. We show that our tool is robust to incomplete data and can be easily applied to datasets where infection timings of individuals are unknown. We tested the reliability of INoDS using simulation experiments of disease spread on a synthetic contact network and find that it is robust to incomplete data and is reliable under different settings of network dynamics and disease contagiousness compared with previous approaches. We demonstrate the applicability of our method in two host-pathogen systems: Crithidia bombi in bumblebee colonies and Salmonella in wild Australian sleepy lizard populations. INoDS thus provides a novel and reliable statistical tool for identifying transmission pathways of infectious disease spread. In addition, application of INoDS extends to understanding the spread of novel or emerging infectious disease, an alternative approach to laboratory transmission experiments, and overcoming common data-collection constraints.

Variations in chemical defences and patterns of natural enemy attack between native and introduced populations of fireweed (Senecio madagascariensis): Implications for biological control

AbstractNative to South Africa, fireweed (Senecio madagascariensis Poiret; Asteraceae) is an annual or short‐lived perennial herb that is highly invasive in Australia, where it is a target for biological control. Preliminary research indicates that fireweed may be undergoing adaptive changes along its invasion gradient in Australia. Changes, such as a shift in plant chemical defence, may influence fireweed’s interaction with specialist insect herbivores, and hence the efficacy of a biocontrol program. As the testing of biocontrol candidates is a rigorous and lengthy process, confirmation of fireweed’s susceptibility to insect attack may assist in fast tracking candidate suitability, where changes in plant defensive chemistry are found. In a large experimental field study in fireweed’s native range, we compared the susceptibility of Australian and South African populations to insect natural enemy attack (in terms of plant biomass, insect richness and composition). Simultaneously, we assessed the variation in plant pyrrolizidine alkaloid concentrations and composition to rationalise any differences in natural enemy attack between populations. We found no significant differences in plant biomass across fireweed populations, despite significantly higher alkaloid concentrations in Australian populations. The composition of the endophagous (specialist) insect herbivore assemblage was related to alkaloid composition, but there were only minor differences in the assemblage between Australian and South African fireweed populations. Moreover, we found no significant differences in the abundance, richness or Shannon diversity indices of endophagous or ectophagous (generalist) insect herbivores between Australian and South African fireweed populations. Our results suggest that despite variations in chemical defence, Australian fireweed populations displayed neither reduced nor increased susceptibility to specialist insect herbivore attack, supporting the notion that if host‐specific biocontrol agents are released, their impact in Australia is unlikely to be influenced by any changes in plant chemical defence.

Developing a protocol for neuroimaging to investigate brain ageing and dementia in collaboration with aboriginal Australian communities

AbstractBackgroundDementia rates in Aboriginal Australians are 3‐5 times higher than in the broader Australian population, and among the highest rates reported globally. Existing evidence suggests that dementia types are similar to those found in non‐Indigenous Australian populations. Neuroimaging, however, has not been previously available in any study of dementia in this population to support or inform clinical diagnoses.MethodThis study extends our epidemiological work, and arose from extensive community consultation and engagement. This engagement included a pilot MRI study (n=14), community planning survey, and guidance from an Aboriginal and Torres Strait Islander Steering Committee. The neuroimaging sub‐study is a prospective, cross‐sectional non‐interventional study. Participants first complete a comprehensive interview and diagnostic assessment as part of the Koori Growing Old Well study. Consenting participants with cognitive decline (diagnosis of cognitive impairment or dementia; n=40) and age/sex‐matched healthy controls (n=40) aged 60+ will undergo MR, FDG PET‐CT and PiB PET‐CT scans. An additional n=120 participants >55 years will be recruited to an MR scan‐only condition.ResultPilot work and consultation showed acceptability of neuroimaging with partnering Aboriginal communities, including 74% of planning survey participants (n=213) indicating that neuroimaging should be included in future dementia studies (Lavrencic et al., 2020, Int Psychogeriatr). Older Aboriginal people living in New South Wales, Australia are currently being recruited; n=20 have undergone PET‐CT and MR scans to date (expected study completion by 2023). Outcome analyses will compare cognitive decline and healthy control groups on a range of measures including amyloid burden, regional glucose metabolism, hippocampal atrophy/volume and vascular indices on MR. Associations between amyloid burden and vascular pathology will be examined for cases of possible/probable Alzheimer’s disease. Correlations between MR measures and early life stress, adult adversity, cognitive function, and clinically diagnosed cognitive impairment will be investigated.ConclusionOur study will, for the first time, investigate functional and anatomical neuroimaging in older Aboriginal Australians and inform dementia prevention, diagnosis and policy for Aboriginal Australians. It will also contribute to the wider literature on vascular risk in the pathogenesis of AD, with associated biomedical and social risk factors across the lifespan of Aboriginal Australians.

Long-acting injectable buprenorphine - 'best practice' opioid agonist therapy for Australian prisoners.

To consider opioid agonist therapy in prisons. Given the substantial risks of substance misuse by prisoners, long-acting injectable buprenorphine should be adopted as 'best practice' treatment in Australian prison populations.

The role of environmental cues in sugar-sweetened beverage consumption using a temporal self-regulation theory framework

Sugar-sweetened beverage consumption is related to adverse health outcomes such as obesity and Type 2 diabetes. The present research further examined the utility of the temporal self-regulation theory in predicting sugar-sweetened beverage consumption. In addition, the research aimed to identify salient cues that trigger intake. Two-hundred and eighty-seven participants were recruited using convenience sampling in US and Australian populations. Hierarchical multiple regression analyses were used, and the final model accounted for 27.1% of the variance in consumption, providing partial support for the temporal self-regulation theory (ƒ2 = 0.37). Intention accounted for a significant 7.0% of variance (R2 = 0.07, p < .001), behavioural prepotency variables (past behaviour, habit, and cues) together combined for an additional 15.1% of variance (R2 = 0.15, p < .001), but neither measure of self-regulatory capacity (trait self-control, inhibition) was a significant predictor. No cues emerged as unique predictors, however the findings suggest that consumption may be influenced by a combination of cues across different situations. Behavioural prepotency moderated the intention-behaviour relationship such that as behavioural prepotency increased, the greater the influence intention had on behaviour. Further support for the role of both intention and automatic processes in sugar-sweetened beverage consumption was garnered, but more research is needed to identify when specific cues influence consumption most.

Genetics Variants associated with Anterior Cruciate Ligament injury in Australia, South Africa, and Japan

Previous small-scale studies have shown an association between the COL5A1 gene and anterior cruciate ligament (ACL) injury risk. In this larger study, the genotype and allele frequency distributions of the COL5A1 rs12722 C/T and rs10628678 AGGG/deletion (AGGG/-) indel variants were compared between: i) participants with ACL injury in independent and combined cohorts from South-Africa (SA) and Australia (AUS) vs controls (CON), and ii) participants with any ligament or only ACL injury in a Japanese (JPN) cohort vs CON. Samples were collected from SA (n=467; n=235 cases; n=232 controls), AUS (n=442; n=362 cases; n=80 controls) and JPN (n=1,903; cases n=500; n=1,403 controls). Genomic DNA was extracted and genotyped. Distributions were compared, and inferred haplotype analyses performed. No independent associations were noted for rs12722 or rs10628678 when the combined SA and AUS cohort was analysed. However, the rs12722-rs10628678 C- inferred haplotype was over-represented in the female SA + AUS CON vs ACL (p=0.040, OR=0.15, CI=0.04-0.56), whereas T- inferred haplotype was over-represented in the ACL SA+AUS participants in female participants (p<0.001, OR=4.74, CI=1.66-13.55). Moreover, the rs12722 C/C genotype was over-represented in JPN ACL vs CON (p=0.039, OR=0.52, 0.27-1.00), and the rs10628678 -/- genotype over-represented with increased risk of ligament injuries (p=0.035, OR=1.31, CI=1.02-1.68) in the JPN cohort. Collectively, these results highlight that a region within the COL5A1 3’-UTR is associated with ligament susceptibility. This must be evaluated in larger cohorts and functional contribution to ligament and knee joint biomechanics further explored. Highlights▪The rs12722 rs10628678 T- inferred haplotype was over-represented with increased risk of ACL rupture in the combined SA and AUS female participants.▪The rs12722 rs10628678 C- inferred haplotype was over-represented with decreased risk of ACL rupture in the combined SA and AUS female participants.▪The rs12722 C/C genotype and rs10628678 -/- genotype was associated with increased risk of ACL rupture and ligament injuries in JPN, respectively.▪A region within the COL5A1 3’-UTR is associated with susceptibility to ligament injuries, ACL rupture in particular, and must be investigated further as it may have a bearing on functional capacity of ligaments or joint biomechanics. Conflict of interest statement: My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of the abstract entitled "COL5A1 Gene variants and ligament injuries in Australian, South African, and Japanese populations" to be presented in the SMA conference in 2021.

Female craniometrics support the \u2018two-layer model\u2019 of human dispersal in Eastern Eurasia

This study reports a cranio-morphometric analysis of female human remains from seven archaeological sites in China, Vietnam and Taiwan that date between 16,000 and 5300 BP. The aim of the analysis is to test the “two-layer” model of human dispersal in eastern Eurasia, using previously unanalysed female remains to balance the large sample of previously-analysed males. The resulting craniometric data indicate that the examined specimens all belong to the “first layer” of dispersal, and share a common ancestor with recent Australian and Papuan populations, and the ancient Jomon people of Japan. The analysed specimens pre-date the expansion of agricultural populations of East/Northeast Asian origin—that is, the “second layer” of human dispersal proposed by the model. As a result of this study, the two-layer model, which has hitherto rested on evidence only from male skeletons, is now strongly supported by female-derived data. Further comparisons reveal that the people of the first layer were closer in terms of their facial morphology to modern Africans and Sri Lankan Veddah than to modern Asians and Europeans, suggesting that the Late Pleistocene through Middle Holocene hunter-gatherers examined in this study were direct descendants of the anatomically modern humans who first migrated out of Africa through southern Eurasia.

Phenotypic differentiation among native, expansive and introduced populations influences invasion success

AbstractAimHumans influence species distributions by modifying the environment and by dispersing species beyond their natural ranges. Populations of species that have established in disjunct regions of the world may exhibit trait differentiation from native populations due to founder effects and adaptations to selection pressures in each distributional region. We compared multiple native, expansive and introduced populations of a single species across the world, considering the influence of environmental stressors and transgenerational effects.LocationUnited States Gulf and Atlantic coasts, United States interior, European Atlantic and Mediterranean coasts, east coast of Australia.TaxonBaccharis halimifolia L. (eastern baccharis).MethodsWe monitored seed germination, seedling emergence, survival and early growth in a common garden experiment, conducted with over 18,200 seeds from 80 populations. We also evaluated the influence of environmental stress and maternal traits on progeny performance.ResultsIntroduced European Atlantic populations had faster germination and early growth than native populations. However, this was not the case for the more recently naturalized European Mediterranean populations. Introduced Australian populations grew faster than native populations in non‐saline environments but had lower survival in saline conditions commonly encountered in the native range. Similarly, expansive inland US populations germinated faster than coastal native populations in non‐saline environments but grew and germinated more slowly in saline environments. Maternal inflorescence and plant size were positively related with seed germination and seedling survival, whereas flower abundance was positively correlated with seedling early growth and survival. However, maternal traits explained a much lower fraction of the total variation in early demographic stages of B. halimifolia than did distributional range.Main conclusionsPhenotypic differentiation could allow B. halimifolia to adapt to different biotic and abiotic selection pressures found in each distributional range, potentially contributing to its success in introduced and expansive ranges.

The Gene-Drug Duality: Exploring the Pharmacogenomics of Indigenous Populations.

While pharmacogenomic studies have facilitated the rapid expansion of personalized medicine, the benefits of these findings have not been evenly distributed. Genomic datasets pertaining to Indigenous populations are sorely lacking, leaving members of these communities at a higher risk of adverse drug reactions (ADRs), and associated negative outcomes. Australia has one of the largest Indigenous populations in the world. Pharmacogenomic studies of these diverse Indigenous Australian populations have been hampered by a paucity of data. In this article, we discuss the history of pharmacogenomics and highlight the inequalities that must be addressed to ensure equal access to pharmacogenomic-based healthcare. We also review efforts to conduct the pharmacogenomic profiling of chronic diseases among Australian Indigenous populations and survey the impact of the lack of drug safety-related information on potential ADRs among individuals in these communities.

A health political science for health promotion.

If health promotion as a field of change for human and ecological health is to maintain its urgency, it needs to continue building its policy credentials. This paper charts the development of policy as a concern for IUHE/IUHPE (International Union for Health Education/International Union for Health Promotion and Education) from the mid-1970s when 'health education policies' were prominent issues, to the launch of Healthy Public Policy (in the 1980s) and Health in All Policy (in the 2000s). We argue that solid conceptual and theoretical foundations exist to frame and develop the relevance and connectedness of health promotion more prominently. We start off with a brief introduction into (health) political science, and then illustrate the urgency of the argument with three case studies. The first takes a critical realist perspective on 'closing the gap' in Australian Indigenous populations. With recent evidence it demonstrates that the core of the policymaking process needs to re-align itself with an Indigenous narrative. The second case study reviews the politics of healthy urban planning and health equity in cities. Taking a critical theory institutionalist view, the case describes how the political and narrative parallels between urban theory and health equity have gone underexplored. With an explicit gaze to connect the two, the field could become a large and influential driver of enhanced health promotion and public health policy. The third case describes the languages, policy frames, and distinctions, in four urban/health paradigms. It shows that unconscious policy and practice bias exists in policy priorities and processes. We conclude with observations and recommendations on the role of health promotion as a conceptual realm and field of activity. We show that all health promoters should be aware of the political nature of their enterprise. Tools and analyses exist to help further action.

Association Between Enterovirus Infection and Type 1 Diabetes Risk: A Meta-Analysis of 38 Case-Control Studies.

ObjectiveThe association between enterovirus infection and type 1 diabetes (T1D) is controversial, and this meta-analysis aimed to explore the correlation.MethodsPubMed, Embase, Web of Science, and Cochrane Database were searched from inception to April 2020. Studies were included if they could provide sufficient information to calculate odds ratios and 95% confidence intervals. All analyses were performed using STATA 15.1.ResultsThirty-eight studies, encompassing 5921 subjects (2841 T1D patients and 3080 controls), were included. The pooled analysis showed that enterovirus infection was associated with T1D (P < 0.001). Enterovirus infection was correlated with T1D in the European (P < 0.001), African (P = 0.002), Asian (P = 0.001), Australian (P = 0.011), and Latin American (P = 0.002) populations, but no conclusion could be reached for North America. The association between enterovirus infection and T1D was detected in blood and tissue samples (both P < 0.001); no association was found in stool samples.ConclusionOur findings suggest that enterovirus infection is associated with T1D.

Phylogeography of the wide-host range panglobal plant pathogen Phytophthora cinnamomi.

Various hypotheses have been proposed regarding the origin of the plant pathogen Phytophthora cinnamomi. P.cinnamomi is a devastating, highly invasive soilborne pathogen associated with epidemics of agricultural, horticultural and forest plantations and native ecosystems worldwide. We conducted a phylogeographic analysis of populations of this pathogen sampled in Asia, Australia, Europe, southern and northern Africa, South America, and North America. Based on genotyping-by-sequencing, we observed the highest genotypic diversity in Taiwan and Vietnam, followed by Australia and South Africa. Mating type ratios were in equal proportions in Asia as expected for a sexual population. Simulations based on the index of association suggest a partially sexual, semi-clonal mode of reproduction for the Taiwanese and Vietnamese populations while populations outside of Asia are clonal. Ancestral area reconstruction provides new evidence supporting Taiwan as the ancestral area, given our sample, indicating that this region might be near or at the centre of origin for this pathogen as speculated previously. The Australian and South African populations appear to be a secondary centre of diversity following migration from Taiwan or Vietnam. Our work also identified two panglobal, clonal lineages PcG1-A2 and PcG2-A2 of A2mating type found on all continents. Further surveys of natural forests across Southeast Asia are needed to definitively locate the actual centre of origin of this important plant pathogen.

WMel Wolbachia genome remains stable after 7 years in Australian Aedes aegypti field populations.

Infection of wMel Wolbachia in Aedes aegypti imparts two signature features that enable its application for biocontrol of dengue. First, the susceptibility of mosquitoes to viruses such as dengue and Zika is reduced. Second, a reproductive manipulation is caused that enables wMel introgression into wild-type mosquito populations. The long-term success of this method relies, in part, on evolution of the wMel genome not compromising the critical features that make it an attractive biocontrol tool. This study compared the wMel Wolbachia genome at the time of initial releases and 1–7 years post-release in Cairns, Australia. Our results show the wMel genome remains highly conserved up to 7 years post-release in gene sequence, content, synteny and structure. This work suggests the wMel genome is stable in its new mosquito host and, therefore, provides reassurance on the potential for wMel to deliver long-term public-health impacts.

The evolution of targeted cannibalism and cannibal-induced defenses in invasive populations of cane toads

Biotic conflict can create evolutionary arms races, in which innovation in one group increases selective pressure on another, such that organisms must constantly adapt to maintain the same level of fitness. In some cases, this process is driven by conflict among members of the same species. Intraspecific conflict can be an especially important selective force in high-density invasive populations, which may favor the evolution of strategies for outcompeting or eliminating conspecifics. Cannibalism is one such strategy; by killing and consuming their intraspecific competitors, cannibals enhance their own performance. Cannibalistic behaviors may therefore be favored in invasive populations. Here, we show that cane toad tadpoles (Rhinella marina) from invasive Australian populations have evolved an increased propensity to cannibalize younger conspecifics as well as a unique adaptation to cannibalism-a strong attraction to vulnerable hatchlings-that is absent in the native range. In response, vulnerable conspecifics from invasive populations have evolved both stronger constitutive defenses and greater cannibal-induced plastic responses than their native range counterparts (i.e., rapid prefeeding development and inducible developmental acceleration). These inducible defenses are costly, incurring performance reductions during the subsequent life stage, explaining why plasticity is limited in native populations where hatchlings are not targeted by cannibalistic tadpoles. These results demonstrate the importance of intraspecific conflict in driving rapid evolution, highlight how plasticity can facilitate adaptation following shifts in selective pressure, and show that evolutionary processes can produce mechanisms that regulate invasive populations.

The effect of national disease-modifying therapy subsidy policy on long-term disability outcomes in people with multiple sclerosis

Background: Disease-modifying therapies (DMTs) are used to treat people with relapsing-onset multiple sclerosis (ROMS), but our knowledge is largely limited to their short-term effects. Objective: To determine (1) the impact of national-level DMT subsidy policy on DMT use and health outcomes in people with MS (PwMS) and (2) the long-term effects of DMT on disability and quality of life (QoL; 5-level EQ-5D version (EQ-5D-5L) utility value). Methods: This observational cohort study compared Australian and New Zealand populations with different levels of DMT availability 10–20 years post-ROMS diagnosis. Between-country differences were assessed using standardised differences. Associations were assessed with multivariable linear regression models. Results: We recruited 328 Australians and 256 New Zealanders. The Australian cohort had longer DMT treatment duration, greater proportion of disease course treated and shorter duration between diagnosis and starting DMT. The Australian cohort had lower median Expanded Disability Status Scale (EDSS) (3.5 vs 4.0) and Multiple Sclerosis Severity Score (MSSS) (3.05 vs 3.71) and higher QoL (0.71 vs 0.65). In multivariable models, between-country differences in disability and QoL were largely attributed to differential use of DMT. Conclusions: This study provides evidence for the impact of national-level DMT policy on disability outcomes in PwMS. Where DMTs are more accessible, PwMS experienced less disability progression and improved QoL 10–20 years post-diagnosis.

Seroprevalence of hepatitis B antibodies among international and domestic university students.

Chronic hepatitis B prevalence is low in most Australian populations, with universal infant HBV vaccination introduced in 2000. Migrants from high prevalence countries are at risk of acquisition before arrival and non-immune adults are potentially at risk through skin penetrating procedures and sexual contact, particularly during international travel. The risk profile of young adult students, many from high prevalence countries, is inadequately understood. A cross-sectional online survey conducted among university students collected data on demographic, vaccination and travel characteristics and blood samples were tested for hepatitis B surface antibody (HBsAb) and hepatitis B core antibody (HBcAb). Analyses identified factors associated with HBsAb seroprevalence and self-reported vaccination. The serosurvey was completed by 804 students born between 1988 and 1993, with 613/804 (76.2%, 95% CI 73.2-79.1) self-reporting prior HBV vaccination. Overall, 526/804 (65.4%, 95% CI 62.0%-68.6%) students were seropositive to HBsAb, including 438/613 (71.5%, 95% CI 67.8-74.9) students self-reporting a prior HBV vaccine and 88/191 (46.1%, 95% CI 39.2-53.2) students self-reporting no prior HBV vaccine. Overall, 8/804 (1.0%, 95% CI 0.5%-2.0%) students were HBcAb positive, of whom 1/804 (0.1%, 95% CI 0.02%-0.7%) was currently infectious. The prevalence of chronic HBV infection was low. However, more than one in four students were susceptible to HBV and over-estimated their immunity. Future vaccination efforts should focus on domestic students born before the introduction of the infant program and all international students. Screening and vaccination of students, including through campus-based health services, are an opportunity to catch-up young adults prior to undertaking at-risk activities, including international travel.

Genetic diversity and population structure of six South African Acacia mearnsii breeding populations based on SSR markers.

Black wattle (Acacia mearnsii) has great economic value as a commercial source of tannins, timber and a source of firewood for local and international markets. It has been suggested that to maximize the genetic gain of A. mearnsii plantations in South Africa, the gene pool that exist within ICFR needs to be broadened via introduction of new genotypes with diverse traits. In this work, 282 A. mearnsii samples sourced from the ICFR breeding program were genotyped using 11 cross-species SSR markers. Our results showed low to moderate genetic differentiation (FST) among the six breeding subpopulations, with positive inbreeding (FIS) values that could be attributed to an historical inbreeding event. Low levels of relatedness could however indicate some mechanism of inbreeding avoidance. The effects from a recent supplementation of genetic material from two native Australian populations were observed through genetic structuring analyses. Analysis of molecular variance (AMOVA) revealed that significant genetic variation was mainly distributed within populations (75%) and among individuals (23%). The results provide significant information on A. mearnsii population genetic diversity and structure, which can be used for conservation of the current subpopulations and future tree improvement programs.

Improved detection of flaviviruses in Australian mosquito populations via replicative intermediates.

Mosquito-borne flaviviruses are significant contributors to the arboviral disease burdens both in Australia and globally. While routine arbovirus surveillance remains a vital exercise to identify known flaviviruses in mosquito populations, novel or divergent and emerging species can be missed by these traditional methods. The MAVRIC (monoclonal antibodies to viral RNA intermediates in cells) system is an ELISA-based method for broad-spectrum isolation of positive-sense and double-stranded RNA (dsRNA) viruses based on detection of dsRNA in infected cells. While the MAVRIC ELISA has successfully been used to detect known and novel flaviviruses in Australian mosquitoes, we previously reported that dsRNA could not be detected in dengue virus-infected cells using this method. In this study we identified additional flaviviruses which evade detection of dsRNA by the MAVRIC ELISA. Utilising chimeric flaviviruses we demonstrated that this outcome may be dictated by the non-structural proteins and/or untranslated regions of the flaviviral genome. In addition, we report a modified fixation method that enables improved detection of flavivirus dsRNA and inactivation of non-enveloped viruses from mosquito populations using the MAVRIC system. This study demonstrates the utility of anti-dsRNA monoclonal antibodies for identifying viral replication in insect and vertebrate cell systems and highlights a unique characteristic of flavivirus replication.