Expanding the known distribution of phascolartid gammaherpesvirus 1 in koalas to populations across Queensland and New South Wales

Koala populations across the east coast of Australia are under threat of extinction with little known about the presence or distribution of a potential pathogen, phascolartid gammaherpesvirus 1 (PhaHV-1) across these threatened populations. Co-infections with PhaHV-1 and Chlamydia pecorum may be common and there is currently a limited understanding of the impact of these co-infections on koala health. To address these knowledge gaps, archived clinical and field-collected koala samples were examined by quantitative polymerase chain reaction to determine the distribution of PhaHV-1 in previously untested populations across New South Wales and Queensland. We detected PhaHV-1 in all regions surveyed with differences in detection rate between clinical samples from rescued koalas (26%) and field-collected samples from free-living koalas (8%). This may reflect increased viral shedding in koalas that have been admitted into care. We have corroborated previous work indicating greater detection of PhaHV-1 with increasing age in koalas and an association between PhaHV-1 and C. pecorum detection. Our work highlights the need for continued surveillance of PhaHV-1 in koala populations to inform management interventions, and targeted research to understand the pathogenesis of PhaHV-1 and determine the impact of infection and co-infection with C. pecorum.

Development of diagnostic and point of care assays for a gammaherpesvirus infecting koalas

The recent listing of koala populations as endangered across much of their range has highlighted the need for better management interventions. Disease is a key threat to koala populations but currently there is no information across the threatened populations on the distribution or impact of a gammaherpesvirus, phascolarctid gammaherpesvirus 1 (PhaHV-1). PhaHV-1 is known to infect koalas in southern populations which are, at present, not threatened. Current testing for PhaHV-1 involves lengthy laboratory techniques that do not permit quantification of viral load. In order to better understand distribution, prevalence and impacts of PhaHV-1 infections across koala populations, diagnostic and rapid point of care tests are required. We have developed two novel assays, a qPCR assay and an isothermal assay, that will enable researchers, clinicians and wildlife managers to reliably and rapidly test for PhaHV-1 in koalas. The ability to rapidly diagnose and quantify viral load will aid quarantine practices, inform translocation management and guide research into the clinical significance and impacts of PhaHV-1 infection in koalas.

Differences in constitutive innate immunity between divergent Australian marsupials

Understanding immunity in wildlife populations is important from both One Health and conservation perspectives. The constitutive innate immune system is the first line of defence against pathogens, and comparisons among taxa can test the impact of evolution and life history on immune function. We investigated serum bacterial killing ability (BKA) of five marsupial species that employ varying life history strategies, demonstrated to influence immunity in other vertebrates. The brushtail possum and eastern grey kangaroo had the greatest BKA, while ringtail possums and koalas had the least. These differences were independent of social structure, captivity status and phylogeny, but were associated with diet and body size. Sex and disease status had no effect on BKA in koalas, however potential for differences between wild and captive koalas warrants further investigation. The current study has provided a foundation for future investigations into how adaptive and innate immunity interact in marsupials from an eco-evolutionary perspective.

Future-proofing the koala: synergising genomic and environmental data for effective species management

Climatic and evolutionary processes are inextricably linked to conservation. Avoiding extinction in rapidly changing environments often depends upon a species' capacity to adapt in the face of extreme selective pressures. Here, we employed exon capture and high-throughput next-generation sequencing to investigate the mechanisms underlying population structure and adaptive genetic variation in the koala (Phascolarctos cinereus), an iconic Australian marsupial that represents a unique conservation challenge because it is not uniformly threatened across its range. An examination of 250 specimens representing 91 wild source locations revealed that five major genetic clusters currently exist on a continental scale. The initial divergence of these clusters appears to have been concordant with the Mid-Brunhes Transition (∼ 430-300 kya), a major climatic reorganization that increased the amplitude of Pleistocene glacial-interglacial cycles. While signatures of polygenic selection and environmental adaptation were detected, strong evidence for repeated, climate-associated range contractions and demographic bottleneck events suggests that geographically isolated refugia may have played a more significant role in the survival of the koala through the Pleistocene glaciation than in situ adaptation. Consequently, the conservation of genome-wide genetic variation must be aligned with the protection of core koala habitat to increase the resilience of threatened populations to accelerating anthropogenic threats. Finally, we propose that the five major genetic clusters identified in this study should be accounted for in future koala conservation efforts (e.g. guiding translocations), as existing management divisions in the states of Queensland and New South Wales do not reflect historic or contemporary population structure.

First evidence of deviation from Mendelian proportions in a conservation programme

Classic Mendelian inheritance is the bedrock of population genetics and underpins pedigree-based management of animal populations. However, assumptions of Mendelian inheritance might not be upheld in conservation breeding programmes if early viability selection occurs, even when efforts are made to equalise genetic contributions of breeders. To test this possibility, we investigated deviations from Mendelian proportions in a captive metapopulation of the endangered Tasmanian devil. This marsupial population is ideal for addressing evolutionary questions in conservation due to its large size, range of enclosure types (varying in environmental conditions), good genomic resources (which aid interpretation), and the species' biology. Devil mothers give birth to more offspring than they can nurse in the pouch, providing the potential for intense viability selection amongst embryos. We used data from 140 known sire-dam-offspring triads to isolate within-family selection from population-level mechanisms (such as mate choice or inbreeding), and compared observed offspring genotypes at 123 targeted SNPs to neutral (i.e., Mendelian) expectations. We found lower offspring heterozygosity than expected, and subtle patterns that varied across a gradient of management intensity from zoo-like enclosures to semi-wild environments for some loci. Meiotic drive or maternal-foetal incompatibilities are consistent with our results, although we cannot statistically confirm these mechanisms. We found some evidence that maternal genotype affects annual litter size, suggesting that family-level patterns are driven by differential offspring mortality before birth or during early development. Our results show that deviations from Mendelian inheritance can occur in conservation programmes, despite best-practice management to prevent selection.

Characterization of reproductive gene diversity in the endangered Tasmanian devil

Interindividual variation at genes known to play a role in reproduction may impact reproductive fitness. The Tasmanian devil is an endangered Australian marsupial with low genetic diversity. Recent work has shown concerning declines in productivity in both wild and captive populations over time. Understanding whether functional diversity exists at reproductive genes in the Tasmanian devil is a key first step in identifying genes that may influence productivity. We characterized single nucleotide polymorphisms (SNPs) at 214 genes involved in reproduction in 37 Tasmanian devils. Twenty genes contained nonsynonymous substitutions, with genes involved in embryogenesis, fertilization and hormonal regulation of reproduction displaying greater numbers of nonsynonymous SNPs than synonymous SNPs. Two genes, ADAMTS9 and NANOG, showed putative signatures of balancing selection indicating that natural selection is maintaining diversity at these genes despite the species exhibiting low overall levels of genetic diversity. We will use this information in future to examine the interplay between reproductive gene variation and reproductive fitness in Tasmanian devil populations.

Human remyelination promoting antibody inhibits apoptotic signaling and differentiation through Lyn kinase in primary rat oligodendrocytes

PURPOSE

Human remyelination promoting IgM mAbs target oligodendrocytes (OLs) and function in animal models of multiple sclerosis (MS). However, their mechanism of action is unknown. This study seeks to identify the cellular mechanism of action of a recombinant human IgM on OL survival.

METHODS

Binding of rHIgM22 to the surface of rat OLs was studied by co-localization with various markers. RHIgM22-mediated effects on apoptotic signaling in OLs, differentiation markers, and signaling molecules were detected by Western blotting and immunoprecipitation.

RESULTS

RHIgM22 co-localized with integrin β3 but not other integrin β-chains in OLs. Downstream of integrin β3 we identified Src family kinase (SFK) Lyn as a key player of rHIgM22-mediated actions in OLs. Lyn immunoprecipitated in a complex together with integrin αvβ3 and PDGFαR. Lyn expression was 9-fold up-regulated and Lyn activation was 3-fold higher inrHIgM22-treated OL cultures compared with controls. RHIgM22 inhibited apoptotic signaling by greater than 10-fold reduction of caspase-3 and capsase-9 cleavage and reduced by 4-fold expression of differentiation markers MBP and MOG in OLs. SFK inhibitors PP2 and SU6656 inhibited Lyn activity and restored caspase-cleavage in OLs. A human IgM that did not promote remyelination and medium wereused as controls.

CONCLUSIONS

rHIgM22 prevented apoptotic signaling andinhibited OL differentiation by Lyn implying thatIgM-mediated remyelination is due toprotection of OPC and OLs rather than promotion of OPC differentiation.

The effect of Rapid Induction Analgesia on subjective pain ratings and pain tolerance

The effect of Rapid Induction Analgesia (RIA) on pain tolerance and ratings of mechanically induced pain in the pain-sensitized forearm was investigated in 58 undergraduates. Posthypnotic suggestions of relaxation and analgesia did not influence pain ratings or tolerance, but relaxation ratings increased after RIA. When suggestions for analgesia were made throughout pain testing, ratings of pain unpleasantness at the pain tolerance point decreased more in the RIA group than in the attention control group. However, RIA did not influence pain threshold or tolerance. It was concluded that RIA was more effective in reducing subjective reports of pain (particularly the affective component) than in altering pain tolerance, and that maintenance of hypnotic suggestions was more effective than posthypnotic suggestions of comfort and relaxation in alleviating the affective component of pain.

Rapid induction analgesia for the alleviation of procedural pain during burn care

Burn patients must often endure intense pain during their regular dressing changes. The aim of the present study was to investigate the therapeutic effect of rapid induction analgesia (RIA) on resting and procedural pain, anticipatory anxiety, relaxation levels and medication consumption in 30 hospitalized burn patients. Patients rated levels of pain and relaxation for four burn care sessions. RIA was conducted twice on 15 patients, whereas dressing changes proceeded as usual in 15 control patients. When asked to recall pain during the dressing changes, patients remembered an experience which was worse in its entirety than the average of spot ratings taken during the burn care procedure. However, self-reported ratings of the sensory and affective components of pain decreased significantly during and after RIA, particularly in patients who became readily absorbed, and relaxation increased during burn care. Anticipatory anxiety decreased before dressing changes in the RIA group, and analgesic intake decreased between treatment sessions. The promising outcome of this study confirms RIA as a viable adjunct to narcotic treatment for pain control during burn care.