Journal of Experimental Biology - Latest Issue

• Behavior choices amongst grooming, feeding and courting in Drosophila show contextual flexibility, not an absolute hierarchy of needs

  ABSTRACT

  To determine the algorithmic rules and neural circuits controlling selection amongst competing behaviors, we established assays where adult Drosophila melanogaster choose between grooming and feeding, grooming and courting, or feeding and courting. We found that there is not an absolute hierarchy: while flies typically perform grooming first, they can choose to feed if sufficiently starved, or court if an appropriate female is available. Flies alternate between competing behaviors, performing short bouts of each action rather than completely satisfying one drive before transitioning to another. While we did not do an exhaustive screen, from the candidates we examined, we did not find evidence for a specific genetic or neuronal locus that affects all decisions. We did identify genetic background effects, suggesting that multiple genes may contribute to decision-making priorities. Our results add to a growing body of work on decision making in Drosophila and provide a foundation for future investigation of the exact neural circuits required to achieve appropriate choices.

• ECR Spotlight – Carla Ladd

  ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Carla Ladd is an author on ‘ Behavior choices amongst grooming, feeding and courting in Drosophila show contextual flexibility, not an absolute hierarchy of needs’, published in JEB. Carla is a postdoc in the lab of Kenneth Kosik at the Neuroscience Research Institute, University of California, Santa Barbara, USA, investigating the effects of Alzheimer's Disease on habituation.

• The heart's energy secret: impact of DHA deficiency on cardiac mitochondrial efficiency and thermal performance in sardine ( Sardina pilchardus )

  ABSTRACT

  Climate-induced changes in marine ecosystems are predicted to reduce the production of omega-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA), such as docosahexaenoic acid (DHA), in primary producers. This decline can spread through food webs, reducing DHA availability in small pelagic fish such as sardines. DHA is essential for mitochondrial membrane integrity and ATP production. We tested whether dietary DHA deficiency impairs cardiac mitochondrial function in sardines, limiting their ability to cope with rapid temperature changes. Wild adult sardines reared under laboratory conditions were fed either a control or a DHA-deficient diet at natural fluctuating temperature. After 6 months, we measured in vitro cardiac mitochondria performance from nine individuals per group at 12, 15, 18 and 21°C. DHA-deficient sardines had lower DHA in cardiac cell membranes, leading to reduced mitochondrial efficiency, with increased proton leakage, reduced oxidative phosphorylation and ATP production. High inter-individual variability suggests DHA alone does not fully explain mitochondrial efficiency changes, with additional metabolic mechanisms involved. While mitochondria maintained respiratory capacity up to 21°C, ATP synthesis efficiency declined with temperature, suggesting DHA-deficient sardines may face greater energetic constraints under warming. These findings highlight how dietary changes alter the metabolic resilience in marine ectotherms facing rapid environmental fluctuations, although responses under more extreme temperatures remain to be explored.

• Arctic lake trout can't take the heat

• Sleepy lizards perk up when they smell fire