Life in Low Oxygen: how do naked mole-rats and Siamese fighting fish live in such harsh environments?
Some animals can live under environmental conditions that would cause humans long-lasting harm, and potentially death. Understanding the physiological mechanisms that underpin this ability to live in harsh environments can potentially provide solutions to human health problems, while elucidating how such specific adaptations evolved in the animal Kingdom. Two such examples of species that live in harsh environments - naked mole-rats (Heterocephalus glaber) and Siamese fighting fish (Betta splendens) - inhabit incredibly low oxygen habitats, and are extremely tolerant of environments high in CO2.
The Bathyergidae rodent group, to which mole-rats belong, have been studied extensively for numerous reasons spanning multiple disciplines, due to the many unique features of this assemblage; longevity (they live 30 years despite being 5-inch long rodents), immunity to cancer, lack of muscle wastage with age, unique calcium structure in their teeth, a eusocial society like that of social insects. The Bathyergidae group can also survive CO2 saturations of over 6%. It is thought that the species have unique metabolic pathways that prevent oxygen starvation in the brain, allowing the animals to be highly active in such conditions, but the exact mechanism is not yet known. Outstanding questions about this phenomenon, therefore, are:
(a) how do the metabolic pathways of these species support the resilience to low oxygen concentrations,
(b) what metabolic responses do they show to decreasing oxygen levels, and,
(c) how are the Bathyergidae able to live and perform high activity levels in such low oxygen conditions, and in turn, how is this linked to their oxygen-deficiency resilience. The clue is likely to be related to their subterranean lifestyle. This section of the project is to study the metabolic responses of Bathyergidae members to fluctuations in oxygen concentrations in (i) their natural environments, and (ii) a laboratory setting, via manipulations of oxygen concentrations.
Similarly, Siamese fighting fish inhabit low oxygen environments, yet engage in vigorous territorial displays and aggressive physical interactions. Bettas are facultatively air-breathing freshwater fish, possessing a labyrinth organ that enables them to obtain oxygen directly from the air to supplement aquatic oxygen uptake. During aggressive encounters, male Bettas engage in intense fin and opercular flare displays, which cause significant changes in muscle metabolites and increased rates of oxygen uptake. Bettas are unable to pump water over their gills during the opercular flare displays (gills open) throughout aggressive encounters, and are therefore effectively unable to exchange respiratory gases with water when displaying. This project aims to (i) measure how this species perform high-intensity exercise and locomotive feats under such conditions, (ii) what scope there is for phenotypic plasticity (an individual to change and adapt to environmental perturbation) at the individual level, through experimental manipulation of oxygen levels in the water, and (iii) how territoriality is influenced by fluctuations in oxygen content of the water.
this project operates in conjunction with Dr Chris Faulkes (QMUL), Dr Monica Daley (RVC), Prof Craig White (Monash) and Prof Nigel Bennett (Pretoria)
Proposed start date September 2018
A three year funded studentship based on Research council rates including tuition fees and stipend.
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FTE Category A staff submitted: 24.00
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