85 research outputs found
Ionic and Osmotic Mechanisms Of Insect Chill-Coma And Chilling Injury
A mechanistic understanding of how temperature limits insect performance is needed to accurately model insect distribution and abundance. Upon crossing the temperature of their critical thermal minimum (CTmin), insects enter a state of paralysis (chill-coma). Chill-susceptible insects accumulate injuries (termed chilling injury) during prolonged exposure to low temperatures. My objective was to determine the mechanisms by which both chill-coma and chilling injury manifest in chill-susceptible insects. In aquatic animals, critical thermal limits are associated with a temperature-induced failure of oxygen supply relative to demand (oxygen- and capacity- limitation of thermotolerance; OCLT), which leads to reliance on anaerobic metabolism at thermal extremes. However, using open-flow respirometry and biochemical techniques, I found that fall field crickets (Gryllus pennsylvanicus) in chill-coma continued to exchange gases through the tracheal system and did not accumulate anaerobic byproducts, which suggests OCLT does not set the CTmin of insects. To characterize the patterns of ion balance disruption at low temperatures, I estimated water and ion content of the hemolymph and tissues of G. pennsylvanicus in chill-coma using gravimetric methods and atomic absorption spectrometry. Exposure to low temperatures caused a movement of Na+ and water from the hemolymph to the gut in G. pennsylvanicus, which increased hemolymph [K+] and depolarized muscle resting potential. When removed from the cold, crickets rebalanced ions and water, and the restoration of hemolymph [K+] (and muscle equilibrium potential) was coincident with the recovery of neuromuscular function. Although crickets recover the ability to move rapidly after removal from the cold, complete recovery of ion and water homeostasis requires additional time and metabolic investment. There is both inter- and intraspecific variation in cold tolerance in flies of the genus Drosophila. Using ion-selective microelectrodes, I found that cold-tolerant Drosophila species and cold- acclimated D. melanogaster maintain low concentrations of [Na+] and [K+] in their hemolymph. Drosophila cold tolerance was also associated with low Na+/K+-ATPase activity on a whole-organism level. Together, these studies allow me to construct a conceptual model of how the direct effects of temperature on ion homeostasis may drive chill-coma, chill-coma recovery and chilling injury in insects
The capacity to maintain ion and water homeostasis underlies interspecific variation in Drosophila cold tolerance
Many insects, including Drosophila, succumb to the physiological effects of chilling at temperatures well above those causing freezing. Low temperature causes a loss of extracellular ion and water homeostasis in such insects, and chill injuries accumulate. Using an integrative and comparative approach, we examined the role of ion and water balance in insect chilling susceptibility/ tolerance. The Malpighian tubules (MT), of chill susceptible Drosophila species lost [Na+] and [K+] selectivity at low temperatures, which contributed to a loss of Na+ and water balance and a deleterious increase in extracellular [K+]. By contrast, the tubules of chill tolerant Drosophila species maintained their MT ion selectivity, maintained stable extracellular ion concentrations, and thereby avoided injury. The most tolerant species were able to modulate ion balance while in a cold-induced coma and this ongoing physiological acclimation process allowed some individuals of the tolerant species to recover from chill coma during low temperature exposure. Accordingly, differences in the ability to maintain homeostatic control of water and ion balance at low temperature may explain large parts of the wide intra- and interspecific variation in insect chilling tolerance
Cross-tolerance and cross-talk in the cold: relating low temperatures to desiccation and immune stress in insects.
Multiple stressors, both abiotic and biotic, often are experienced simultaneously by organisms in nature. Responses to these stressors may share signaling pathways ( cross-talk ) or protective mechanisms ( cross-tolerance ). Temperate and polar insects that must survive the winter experience low temperatures accompanied by additional abiotic stressors, such as low availability of water. Cold and desiccation have many similar effects at a cellular level, and we present evidence that the cellular mechanisms that protect against cold stress also protect against desiccation, and that the responses to cold and dehydration likely evolved as cross-tolerance. By contrast, there are several lines of evidence suggesting that low temperature stress elicits an upregulation of immune responses in insects (and vice versa). Because there is little mechanistic overlap between cold stress and immune stress at the cellular level, we suggest that this is cross-talk. Both cross-talk and cross-tolerance may be adaptive and likely evolved in response to synchronous stressors; however, we suggest that cross-talk and cross-tolerance may lead to different responses to changes in the timing and severity of multiple stress interactions in a changing world. We present a framework describing the potentially different responses of cross-tolerance and cross-talk to a changing environment and describe the nature of these impacts using interaction of cold-desiccation and cold-immunity in overwintering insects as an example
Elevating the impact of conservation physiology by building a community devoted to excellence, transparency, ethics, integrity and mutual respect
[Extract] Ten years ago, the journal Conservation Physiology was launched jointly by the Society for Experimental Biology and Oxford University Press. Much has been accomplished since 2012 including publishing over 600 papers in the journal and helping to build a sense of place for aspiring and practicing conservation physiologists (Cooke et al., 2020). Yet, more work is needed to further elevate the impact of conservation physiology as a discipline and community. Here, we summarize what is needed to build and strengthen a community devoted to not only excellence, transparency, ethics, integrity and mutual respect, but also courage to tackle some of the overarching challenges humanity faces. As active voices in the conservation physiology community we hope that this paper will help shape the future of our discipline while also guiding the activities and priorities of the journal and editorial team.
Since the term ‘conservation physiology’ was coined by Wikelski and Cooke (2006) it has emerged as an essential component of conservation science and practice. Conservation physiology is about the use of physiological tools, knowledge and concepts to understand and solve conservation problems across diverse taxa (Cooke et al., 2013). It is regarded as being particularly effective at understanding mechanisms, generating cause–effect relationships (e.g. threat X does Y to organism Z), creating predictive tools and testing conservation interventions (Cooke and O’Connor, 2010). Issues relevant to conservation physiology range from very local, focused on recovery of an imperilled population (Birnie-Gauvin et al., 2017), to global-scale issues such as tackling the UN Sustainable Development Goals (Cooke et al., 2020) and the climate crisis (Madliger et al., 2021c). The discipline is now supported by a conceptual framework (Coristine et al., 2014), a journal (https://academic.oup.com/conphys) and a reference book (Madliger et al. 2021a). There is also a growing community of researchers who engage in conservation physiology and even define themselves as conservation physiologists (Madliger et al., 2021b). Moreover, in conservation physiology there are success stories that demonstrate the potential of conservation physiology (Madliger et al., 2016)
One hundred research questions in conservation physiology for generating actionable evidence to inform conservation policy and practice
Environmental change and biodiversity loss are but two of the complex challenges facing conservation practitioners and policy makers. Relevant and robust scientific knowledge is critical for providing decision-makers with the actionable evidence needed to inform conservation decisions. In the Anthropocene, science that leads to meaningful improvements in biodiversity conservation, restoration and management is desperately needed. Conservation Physiology has emerged as a discipline that is well-positioned to identify the mechanisms underpinning population declines, predict responses to environmental change and test different in situ and ex situ conservation interventions for diverse taxa and ecosystems. Here we present a consensus list of 10 priority research themes. Within each theme we identify specific research questions (100 in total), answers to which will address conservation problems and should improve the management of biological resources. The themes frame a set of research questions related to the following: (i) adaptation and phenotypic plasticity; (ii) human-induced environmental change; (iii) human-wildlife interactions; (iv) invasive species; (v) methods, biomarkers and monitoring; (vi) policy, engagement and communication; (vii) pollution; (viii) restoration actions; (ix) threatened species; and (x) urban systems. The themes and questions will hopefully guide and inspire researchers while also helping to demonstrate to practitioners and policy makers the many ways in which physiology can help to support their decisions
Reframing conservation physiology to be more inclusive, integrative, relevant and forward-looking: Reflections and a horizon scan
Applying physiological tools, knowledge and concepts to understand conservation problems (i.e. conservation physiology) has becomecommonplace and confers an ability to understand mechanistic processes,develop predictive models and identify cause-and-effect relationships. Conservation physiology is making contributions to conservation solutions; the number of \u27success stories\u27 is growing, but there remain unexplored opportunities for which conservation physiology shows immense promise and has the potential to contribute to major advances in protecting and restoring biodiversity. Here, we consider howconservation physiology has evolved with a focus on reframing the discipline to be more inclusive and integrative.Using a \u27horizon scan\u27,we further exploreways in which conservation physiology can be more relevant to pressing conservation issues of today (e.g. addressing the Sustainable Development Goals; delivering science to support the UN Decade on Ecosystem Restoration), aswell as more forward-looking to inform emerging issues and policies for tomorrow. Our horizon scan provides evidence that, as the discipline of conservation physiology continues to mature, it provides a wealth of opportunities to promote integration, inclusivity and forward-thinking goals that contribute to achieving conservation gains. To advance environmentalmanagementand ecosystemrestoration,we need to ensure that the underlying science (such as that generated by conservation physiology) is relevant with accompanying messaging that is straightforward and accessible to end users
Real-time measurement of metabolic rate during freezing and thawing of the wood frog, Rana sylvatica: Implications for overwinter energy use
Ectotherms overwintering in temperate ecosystems must survive low temperatures while conserving energy to fuel post-winter reproduction. Freeze-tolerant wood frogs, Rana sylvatica, have an active response to the initiation of ice formation that includes mobilising glucose from glycogen and circulating it around the body to act as a cryoprotectant. We used flow-through respirometry to measure CO2 production (VCO2) in real time during cooling, freezing and thawing. CO2 production increases sharply at three points during freeze-thaw: at +1°C during cooling prior to ice formation (total of 104±17 μl CO2 frog-1 event-1), at the initiation of freezing (565±85 μl CO 2 frog-1 freezing event-1) and after the frog has thawed (564±75 μl CO2 frog-1 freezing event-1). We interpret these increases in metabolic rate to represent the energetic costs of preparation for freezing, the response to freezing and the re-establishment of homeostasis and repair of damage after thawing, respectively. We assumed that frogs metabolise lipid when unfrozen and that carbohydrate fuels metabolism during cooling, freezing and thawing, and when frozen. We then used microclimate temperature data to predict overwinter energetics of wood frogs. Based on the freezing and melting points we measured, frogs in the field were predicted to experience as many as 23 freeze-thaw cycles in the winter of our microclimate recordings. Overwinter carbohydrate consumption appears to be driven by the frequency of freeze-thaw events, and changes in overwinter climate that affect the frequency of freeze-thaw will influence carbohydrate consumption, but changes that affect mean temperatures and the frequency of winter warm spells will modify lipid consumption
Reframing conservation physiology to be more inclusive, integrative, relevant and forward-looking: reflections and a horizon scan
Applying physiological tools, knowledge and concepts to understand conservation problems (i.e. conservation physiology) has become common place and confers an ability to understand mechanistic processes, develop predictive models and identify cause-and-effect relationships. Conservation physiology is making contributions to conservation solutions; the number of 'success stories' is growing, but there remain unexplored opportunities for which conservation physiology shows immense promise and has the potential to contribute to major advances in protecting and restoring biodiversity. Here, we consider howconservation physiology has evolved with a focus on reframing the discipline to be more inclusive and integrative. Using a 'horizon scan', we further exploreways in which conservation physiology can be more relevant to pressing conservation issues of today (e.g. addressing the Sustainable Development Goals; delivering science to support the UN Decade on Ecosystem Restoration), as well as more forward-looking to inform emerging issues and policies for tomorrow. Our horizon scan provides evidence that, as the discipline of conservation physiology continues to mature, it provides a wealth of opportunities to promote integration, inclusivity and forward-thinking goals that contribute to achieving conservation gains. To advance environmenta lmanagement and ecosystem restoration, we need to ensure that the underlying science (such as that generated by conservation physiology) is relevant with accompanying messaging that is straightforward and accessible to end users
Contributions and perspectives of Indigenous Peoples to the study of mercury in the Arctic
Arctic Indigenous Peoples are among the most exposed humans when it comes to foodborne mercury (Hg). In response,
Hg monitoring and research have been on-going in the circumpolar Arctic since about 1991; this work has been mainly
possible through the involvement of Arctic Indigenous Peoples. The present overview was initially conducted in the
context of a broader assessment of Hg research organized by the Arctic Monitoring and Assessment Programme.
This article provides examples of Indigenous Peoples' contributions to Hg monitoring and research in the Arctic, and
discusses approaches that could be used, and improved upon, when carrying out future activities. Over 40 mercury
projects conducted with/by Indigenous Peoples are identified for different circumpolar regions including the U.S.,
Canada, Greenland, Sweden, Finland, and Russia as well as instances where Indigenous Knowledge contributed to
the understanding of Hg contamination in the Arctic. Perspectives and visions of future Hg research as well as recommendations are presented. The establishment of collaborative processes and partnership/co-production approaches
with scientists and Indigenous Peoples, using good communication practices and transparency in research activities,
are key to the success of research and monitoring activities in the Arctic. Sustainable funding for community-driven
monitoring and research programs in Arctic countries would be beneficial and assist in developing more research/
monitoring capacity and would promote a more holistic approach to understanding Hg in the Arctic. These activities
should be well connected to circumpolar/international initiatives to ensure broader availability of the information and
uptake in policy development
- …