• The Long-Term Effects of Developmental Hypoxia on Cardiac Mitochondrial Function in Snapping Turtles

      Galli, Gina L. J.; email: gina.galli@manchester.ac.uk; Ruhr, Ilan M.; Crossley, Janna; Crossley, Dane A., II (Frontiers Media S.A., 2021-06-28)
      It is well established that adult vertebrates acclimatizing to hypoxic environments undergo mitochondrial remodeling to enhance oxygen delivery, maintain ATP, and limit oxidative stress. However, many vertebrates also encounter oxygen deprivation during embryonic development. The effects of developmental hypoxia on mitochondrial function are likely to be more profound, because environmental stress during early life can permanently alter cellular physiology and morphology. To this end, we investigated the long-term effects of developmental hypoxia on mitochondrial function in a species that regularly encounters hypoxia during development—the common snapping turtle (Chelydra serpentina). Turtle eggs were incubated in 21% or 10% oxygen from 20% of embryonic development until hatching, and both cohorts were subsequently reared in 21% oxygen for 8 months. Ventricular mitochondria were isolated, and mitochondrial respiration and reactive oxygen species (ROS) production were measured with a microrespirometer. Compared to normoxic controls, juvenile turtles from hypoxic incubations had lower Leak respiration, higher P:O ratios, and reduced rates of ROS production. Interestingly, these same attributes occur in adult vertebrates that acclimatize to hypoxia. We speculate that these adjustments might improve mitochondrial hypoxia tolerance, which would be beneficial for turtles during breath-hold diving and overwintering in anoxic environments.
    • The white‐rot fungus, Phanerochaete chrysosporium, under combinatorial stress produces variable oil profiles following analysis of secondary metabolites

      Whiteford, R.; orcid: 0000-0002-2315-8252; email: rory.whiteford@manchester.ac.uk; Nurika, I.; Schiller, T.; Barker, G. (2021-02-25)
      Abstract: Aims: The effects of combinatorial stress on lipid production in Phanerochaete chrysosporium remain understudied. This species of white‐rot fungi was cultivated on solid‐state media while under variable levels of known abiotic and biotic stressors to establish the effect upon fungal oil profiles. Methods and Results: Environmental stressors induced upon the fungus included the following: temperature, nutrient limitation and interspecies competition to assess impact upon oil profiles. Fatty acid type and its concentration were determined using analytical methods of gas chromatography and mass spectrometry. Growth rate under stress was established using high‐performance liquid chromatography with ergosterol as the biomarker. Fungi grown on solid‐state agar were able to simultaneously produce short‐ and long‐chain fatty acids which appeared to be influenced by nutritional composition as well as temperature. Addition of nitrogen supplements increased the growth rate, but lipid dynamics remained unchanged. Introducing competition‐induced stress had significantly altered the production of certain fatty acids beyond that of the monoculture while under nutrient‐limiting conditions. Linoleic acid concentrations, for example, increased from an average of 885 ng μl−1 at monoculture towards 13 820 ng μl−1 at co‐culture, following 7 days of incubation. Conclusions: Interspecies competition produced the most notable impact on lipid production for solid‐state media cultivated fungi while the addition of nitrogen supplementation presented growth and lipid accumulation to be uncorrelated. Combinatorial stress therefore influences the yield of overall lipid production as well as the number of intermediate fatty acids produced, deriving similar oil profiles to the composition of vegetable and fish oils. Significance and Impact of the Study: Fungal secondary metabolism remains highly sensitive following combinatorial stress. The outcome impacts the research towards optimizing fungal oil profiles for biomass and nutrition. Future investigations on fungal stress tolerance mechanisms need to address these environmental factors throughout the experimental design.