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Ca2+ is an integral component of the functional and developmental regulation of the mitochondria. In skeletal muscle, Ca2+ is reported to modulate the rate of ATP resynthesis, regulate the expression of peroxisome proliferator-activated receptor-gamma coactivator 1 (PGC1α) following exercise, and drive the generation of reactive oxygen species (ROS). Due to the latter, mitochondrial Ca2+ overload is recognized as a pathophysiological event but the former events represent important physiological functions in need of tight regulation. Recently, we described the relationship between [Ca2+]mito and resting [Ca2+]cyto and other mitochondrial Ca2+-handling properties of skeletal muscle. An important next step is to understand the triggers for Ca2+ redistribution between intracellular compartments, which determine the mitochondrial Ca2+ load. These triggers in both physiological and pathophysiological scenarios can be traced to the coupled activity of the ryanodine receptor 1 (RyR1) and store-operated Ca2+ entry (SOCE) in the resting muscle. In this piece, we will discuss some issues regarding Ca2+ measurements relevant to mitochondrial Ca2+-handling, the steady-state relationship between cytoplasmic and mitochondrial Ca2+, and the potential implications for Ca2+ handling by muscle mitochondria and cellular function.

Aim: After environmental disasters, species with large population losses may need urgent protection to prevent extinction and support recovery. Following the 2019–2020 Australian megafires, we estimated population losses and recovery in fire-affected fauna, to inform conservation status assessments and management. Location: Temperate and subtropical Australia. Time period: 2019–2030 and beyond. Major taxa: Australian terrestrial and freshwater vertebrates; one invertebrate group. Methods: From > 1,050 fire-affected taxa, we selected 173 whose distributions substantially overlapped the fire extent. We estimated the proportion of each taxon’s distribution affected by fires, using fire severity and aquatic impact mapping, and new distribution mapping. Using expert elicitation informed by evidence of responses to previous wildfires, we estimated local population responses to fires of varying severity. We combined the spatial and elicitation data to estimate overall population loss and recovery trajectories, and thus indicate potential eligibility for listing as threatened, or uplisting, under Australian legislation. Results: We estimate that the 2019–2020 Australian megafires caused, or contributed to, population declines that make 70–82 taxa eligible for listing as threatened; and another 21–27 taxa eligible for uplisting. If so-listed, this represents a 22–26% increase in Australian statutory lists of threatened terrestrial and freshwater vertebrates and spiny crayfish, and uplisting for 8–10% of threatened taxa. Such changes would cause an abrupt worsening of underlying trajectories in vertebrates, as measured by Red List Indices. We predict that 54–88% of 173 assessed taxa will not recover to pre-fire population size within 10 years/three generations. Main conclusions: We suggest the 2019–2020 Australian megafires have worsened the conservation prospects for many species. Of the 91 taxa recommended for listing/uplisting consideration, 84 are now under formal review through national processes. Improving predictions about taxon vulnerability with empirical data on population responses, reducing the likelihood of future catastrophic events and mitigating their impacts on biodiversity, are critical.

Resting skeletal muscle generates heat for endothermy in mammals but not amphibians, while both use the same Ca 2+ -handling proteins and membrane structures to conduct excitation–contraction coupling apart from having different ryanodine receptor (RyR) isoforms for Ca 2+ release. The sarcoplasmic reticulum (SR) generates heat following Adenosine triphosphate (ATP) hydrolysis at the Ca 2+ pump, which is amplified by increasing RyR1 Ca 2+ leak in mammals, subsequently increasing cytoplasmic [Ca 2+ ] ([Ca 2+ ] cyto ). For thermogenesis to be functional, rising [Ca 2+ ] cyto must not interfere with cytoplasmic effectors of the sympathetic nervous system (SNS) that likely increase RyR1 Ca 2+ leak; nor should it compromise the muscle remaining relaxed. To achieve this, Ca 2+ activated, regenerative Ca 2+ release that is robust in lower vertebrates needs to be suppressed in mammals. However, it has not been clear whether: i) the RyR1 can be opened by local increases in [Ca 2+ ] cyto ; and ii) downstream effectors of the SNS increase RyR Ca 2+ leak and subsequently, heat generation. By positioning amphibian and malignant hyperthermia-susceptible human-skinned muscle fibers perpendicularly, we induced abrupt rises in [Ca 2+ ] cyto under identical conditions optimized for activating regenerative Ca 2+ release as Ca 2+ waves passed through the junction of fibers. Only mammalian fibers showed resistance to rising [Ca 2+ ] cyto , resulting in increased SR Ca 2+ load and leak. Fiber heat output was increased by cyclic adenosine monophosphate (cAMP)-induced RyR1 phosphorylation at Ser2844 and Ca 2+ leak, indicating likely SNS regulation of thermogenesis. Thermogenesis occurred despite the absence of SR Ca 2+ pump regulator sarcolipin. Thus, evolutionary isolation of RyR1 provided increased dynamic range for thermogenesis with sensitivity to cAMP, supporting endothermy.

1. Environmental DNA (eDNA) monitoring is a useful tool for species detection but its use in addressing management questions remains scarce. One factor limiting the use of eDNA as a routine monitoring tool is uncertainty around the potential of eDNA data to estimate species abundance. While several confounding factors limit the ability of eDNA data to estimate absolute abundances at large spatial and temporal scales, eDNA data have the potential to estimate relative species abun- dances patterns at smaller scales, and this information can assist management. 2. Environmental DNA and conventional monitoring surveys were conducted in the Abercrombie River catchment (Australia) where an incursion of the invasive red- fin perch (Perca fluviatulis) threatens the survival of a population of endangered Macquarie perch (Macquaria australasica). Species-specific assays were used to quantify eDNA concentrations from water samples and estimate the relative abundance of both species. Electrofishing and fyke netting surveys were used to validate key observations from the eDNA survey. 3. Environmental DNA of both species was detected at all sites except one, where redfin perch DNA was not detected. Between species comparisons of eDNA con- centrations revealed a clear negative relationship between the eDNA concen- trations of both species, consistent with other evidence of redfin perch having a negative impact on Macquarie perch populations. Between site comparisons of redfin perch eDNA concentrations showed evidence of a novel incursion of the species in the upper reaches of the Abercrombie River and conventional monitor- ing in the following year confirmed the pattern of increased redfin perch abun- dances from downstream to upstream sites. 4. Relative comparisons of eDNA concentrations of aquatic species can be used to assess species interactions and reveal unexpected species abundance patterns (e.g. allowing inferences of novel incursions of invasive species). This informa- tion is critical to evaluate current, and design future, management strategies. Consequently, while deriving absolute species abundances from quantitative eDNA data may remain challenging, the use of quantitative eDNA surveys can provide relative abundance patterns valuable to the conservation and manage- ment of invasive and endangered species. 5. The quantitative nature of eDNA survey data has been debated extensively in the current literature because of potential confounding influences. Current study results show that these confounding influences may be less problematic at small spatial scales and quantitative eDNA data can be effective to monitor relative spe- cies abundances patterns.

UK The Supreme Court handed down its judgment in Halliburton v. Chubb in November 2020. The case addressed the test for apparent bias and the issue of arbitrators’ duties of disclosure in English-seated arbitrations. The authors of this article represented the London Court of International Arbitration (LCIA) as interveners in the Supreme Court appeal. This article explores the key points arising out of the judgment and takes stock of the current position under English law. The authors discuss certain issues that remain open following the judgment, including the relationship between the duties of disclosure and confidentiality. They explore the extent to which parties’ adoption of institutional rules can modify the English law position, and comment on the extent to which English law is now in line with that of other jurisdictions. The article notes that Halliburton v. Chubb is one of a number of recent cases globally concerning the scope of arbitrators’ duties. It concludes that while the decision of the Supreme Court provides a welcome degree of clarity as to the English law position, and a necessary confirmation that the English courts take a robust approach to such issues, the judgment itself was necessarily confined to relatively narrow facts. As such, questions relating to arbitrators’ duties are likely to return to the spotlight in future cases, and English law is likely to continue to develop as the relevant principles are applied to different fact patterns and as new norms emerge amongst arbitrators. Halliburton v. Chubb, Arbitrators’ duties, Duty of disclosure, Apparent bias, Conflicts of interest, Impartiality, Challenges to arbitrators, Arbitration Act 1996, Confidentiality, Supreme Court

Significance The evolution of mammals to use skeletal muscle as a source of heat allowed them to spread to all parts of the globe. The generation of heat requires increased adenosine triphosphate (ATP) hydrolysis in the resting muscle in a regulated manner, but how this mechanism works is unknown. The results suggest that mammals increase their RyR1 Ca2+ leak rate to amplify a basal ATP turnover rate at the sarcoplasmic reticulum Ca2+ pump that is higher than that of lower vertebrates. Muscle-based thermogenesis allows regulation of body temperature that is essential for life in mammals and provides a potential pathway for manipulating body weight or temperature by altering metabolic rate., Mammals rely on nonshivering thermogenesis (NST) from skeletal muscle so that cold temperatures can be tolerated. NST results from activity of the sarcoplasmic reticulum (SR) Ca2+ pump in skeletal muscle, but the mechanisms that regulate this activity are unknown. Here, we develop a single-fiber assay to investigate the role of Ca2+ leak through ryanodine receptor 1 (RyR1) to generate heat at the SR Ca2+ pump in resting muscle. By inhibiting a subpopulation of RyR1s in a single-fiber preparation via targeted delivery of ryanodine through transverse tubules, we achieve in-preparation isolation of RyR1 Ca2+ leak. This maneuver provided a critical increase in signal-to-noise of the SR-temperature-sensitive dye ER thermoyellow fluorescence signal from the fiber to allow detection of SR temperature changes as either RyR1 or SR Ca2+ pump activity was altered. We found that RyR1 Ca2+ leak raises cytosolic [Ca2+] in the local vicinity of the SR Ca2+ pump to amplify thermogenesis. Furthermore, gene-dose-dependent increases in RyR1 leak in RYR1 mutant mice result in progressive rises in leak-dependent heat, consistent with raised local [Ca2+] at the SR Ca2+ pump via RyR1 Ca2+ leak. We also show that basal RyR Ca2+ leak and the heat generated by the SR Ca2+ pump in the absence of RyR Ca2+ leak is greater in fibers from mice than from toads. The distinct function of RyRs and SR Ca2+ pump in endothermic mammals compared to ectothermic amphibians provides insights into the mechanisms by which mammalian skeletal muscle achieves thermogenesis at rest.

Store-operated Ca

Aquatic snails serve an important role in the ecosystem. They also play an essential role in the life cycle of many parasites as hosts and may pose risks to animal and human health. In Australia, the role of snails in the transmission of parasites of livestock is well studied. However, despite the country’s unique biodiversity and wildlife, little is known about the role of snails in the transmission and survival of parasites in other ecosystems, including aquatic and aquaculture systems. This study aimed to determine the occurrence of parasites in freshwater snails in the eastern Murray Darling Basin. A total of 275 snails were collected from various localities, including aquaculture fishery ponds and natural creeks during the summer and autumn months in the southern hemisphere. Three different species of freshwater snails, all common to the area, were found, including Bullastra lessoni (n = 11), Isidorella hainesii (n = 157), and Haitia acuta (n = 107), of which 9.1%, 1.3%, and 4.7%, respectively, were found to be harboring various developmental stages of Trematoda. No other parasite was found in the examined snails. Parasites were identified as Choanocotyle hobbsi, Plagiorchis sp. and Petasiger sp. based on the sequences of their ITS2, 18S, and 28S ribosomal DNA region. Herein, we report a native parasite Choanocotyle hobbsi in an introduced snail, Haitia acuta, from both natural and aquaculture ponds. As there are no genetic sequences for adult specimens of Petasiger spp. and Plagiorchis spp. collected in Australia for comparison, whether the specimens collected in this study are the larval stage of one of the previously described species or are a new, undescribed species cannot yet be determined. Our results also suggest snails collected from aquaculture ponds may be infected with considerably more parasites.

Description, RyR1 Ca2+ leak causes a cascade of events that shifts Ca2+ to the cytoplasm and mitochondria, supporting force generation., Muscle contraction depends on tightly regulated Ca2+ release. Aberrant Ca2+ leak through ryanodine receptor 1 (RyR1) on the sarcoplasmic reticulum (SR) membrane can lead to heatstroke and malignant hyperthermia (MH) susceptibility, as well as severe myopathy. However, the mechanism by which Ca2+ leak drives these pathologies is unknown. Here, we investigate the effects of four mouse genotypes with increasingly severe RyR1 leak in skeletal muscle fibers. We find that RyR1 Ca2+ leak initiates a cascade of events that cause precise redistribution of Ca2+ among the SR, cytoplasm, and mitochondria through altering the Ca2+ permeability of the transverse tubular system membrane. This redistribution of Ca2+ allows mice with moderate RyR1 leak to maintain normal function; however, severe RyR1 leak with RYR1 mutations reduces the capacity to generate force. Our results reveal the mechanism underlying force preservation, increased ATP metabolism, and susceptibility to MH in individuals with gain-of-function RYR1 mutations.

Fish species that have no commercial or recreational value are often overlooked in conservation management, despite serious threats to their long-term future. This can be termed the ‘small threatened freshwater fishes’ paradigm. Population viability analysis (PVA) is a useful technique to assess threatened species and conservation management options. While the development and use of population models and population viability analysis is common in conservation, and often used for larger fishes, this has not been so for small threatened freshwater species. This study uses the PVA process to develop a stochastic population model for Nannoperca australis (southern pygmy perch) in temperate south-eastern Australia. The model was most sensitive to early life-history survival rates, for which there were no estimates from field data, compared with other model uncertainty. This study also found that the oldest age class had the highest reproductive value, providing unique support to the value of big, old, fat and fecund fish (BOFFFs) in sustaining natural populations. Modelling indicated that a population in stable habitat supporting about 2000 female adults would likely to be viable, able to withstand some disturbance and possibly be used as a source population for reintroductions. In reality, however, there are few populations in the wild of sufficient size to withstand such take for translocations and hence the production of fish through hatchery means may be required. This type of approach should prove useful for the conservation management of many similar species globally.

On-ground management actions targeting invasive and/or native species are often undertaken based on incomplete and biased distribution data for the species of interest. Once an invasive species becomes established, containment can provide an effective management option to conserve native biodiversity only if it is implemented beyond the outer distribution limits of the species of interest. Determining these outer distribution limits is currently difficult for freshwater fish species because of the low sensitivity and biases associated with conventional monitoring methods. The improved sensitivity of environmental DNA-based surveys makes them particularly useful to determine these outer distribution limits. In this study, we used conventional monitoring methods and eDNA-based monitoring using real-time PCR to determine the spread of the invasive redfin perch (Perca fluviatilis) in an intermittent river system. This voracious predatory fish is responsible for the continued decline of several threatened and vulnerable species within Australia. We found that eDNA detection rates were high in our study system, when redfin perch presence was confirmed by conventional monitoring, compared to previously published works. Additionally we describe how the combination of conventional and eDNA-based monitoring can improve redfin perch distribution data compared to conventional monitoring alone. This improvement has subsequently been used to inform management and determine the optimal location for the construction of an exclusion barrier.

The Murray–Darling Basin (MDB) is Australia’s food bowl, contributing 40% of agricultural production and supporting a population of over 4 million people. Historically, the MDB supported a unique native fish community with significant cultural, subsistence, recreational, commercial and ecological values. Approximately one-quarter of the MDB’s native species are endemic. Changes to river flows and habitats have led to a >90% decline in native fish populations over the past 150 years, with almost half the species now of conservation concern. Commercial fisheries have collapsed, and important traditional cultural practices of First Nations People have been weakened. The past 20 years have seen significant advances in the scientific understanding of native fish ecology, the effects of human-related activities and the recovery measures needed. The science is well established, and some robust restoration-enabling policies have been initiated to underpin actions. What is now required is the political vision and commitment to support investment to drive long-term recovery. We present a summary of 30 priority activities urgently needed to restore MDB native fishes.

Many freshwater fishes are imperilled globally, and there is a need for easily accessible, contemporary ecological knowledge to guide management. This compendium contains knowledge collated from over 600 publications and 27 expert workshops to support the restoration of 9 priority native freshwater fish species, representative of the range of life-history strategies and values in south-eastern Australia’s Murray–Darling Basin. To help prioritise future research investment and restoration actions, ecological knowledge and threats were assessed for each species and life stage. There is considerable new knowledge (80% of publications used were from the past 20 years), but this varied among species and life stages, with most known about adults, then egg, juvenile and larval stages (in that order). The biggest knowledge gaps concerned early life stage requirements, survival, recruitment, growth rates, condition and movements. Key threats include reduced longitudinal and lateral connectivity, altered flows, loss of refugia, reductions in both flowing (lotic) and slackwater riverine habitats, degradation of wetland habitats, alien species interactions and loss of aquatic vegetation. Examples and case studies illustrating the application of this knowledge to underpin effective restoration management are provided. This extensive ecological evidence base for multiple species is presented in a tabular format to assist a range of readers.

Greenshell™ mussels (GSM–Perna canaliculus) are a source of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). Farmed GSM are considered to be a sustainable source of LC-PUFA as they require no dietary inputs, gaining all of their oil by filter-feeding microorganisms from sea water. GSM oil is a high-value product, with a value as much as 1000 times that of fish oils. GSM oil has important health benefits, for example, anti-inflammatory activity. It also contains several minor lipid components that are not present in most fish oil products, and that have their own beneficial effects on human health. We have shown the lipid content of the female GSM (1.9 g/100 g ww) was significantly greater than that of the male (1.4 g/100 g ww). Compared with male GSM, female GSM contained more n-3 LC-PUFA, and stored a greater proportion of total lipid in the gonad and mantle. The higher lipid content in the female than the male GSM is most likely related to gamete production. This information will be useful to optimize extraction of oils from GSM, a local and sustainable source of n-3 LC-PUFA.

(2008). Foakes v Beer and Promissory Estoppel: A Step Too Far. King's Law Journal: Vol. 19, No. 3, pp. 630-636.