Nutrient and toxin interactions in neurodegenerative disease

Flight activity and effort of breeding pied flycatchers in the wild, revealed with accelerometers and machine learning

Flight behaviours of birds have been extensively studied from different angles such as their kinematics, aerodynamics and, more generally, their migration patterns. Nevertheless, much is still unknown about the daily foraging flight activity and behaviour of breeding birds, and potential differences among males and females. The recent development of miniaturized accelerometers allows us a glimpse into the daily life of a songbird. Here, we tagged 13 male and 13 female pied flycatchers (Ficedula hypoleuca) with accelerometers and used machine learning approaches to analyse their flight activity and effort during the chick rearing period. We found that during 2 h of foraging, chick-rearing pied flycatchers were flying on average 13.7% of the time. Almost all flights (>99%) were short flights lasting less than 10 s. Flight activity changed throughout the day and was highest in the morning and lowest in the early afternoon. Male pied flycatchers had lower wing loading than females, and in-flight accelerations were inversely correlated with wing loading. Despite this, we found no significant differences in flight duration and intensity between sexes. This suggests that males possess a higher potential flight performance, which they did not fully utilize during foraging flights.

Striatal metabolism of hexanal, a lipid peroxidation product, in the rat

Free radical induced lipid peroxidation may play a role in neurodegeneration and peroxidation leads to the formation of hexanal from omega-6 fatty acids. We have previously demonstrated in vitro that pyruvate dehydrogenase (PDH) catalyzes the condensation of saturated aldehydes with pyruvate to form acyloins. We have further shown in perfused rat heart that hexanal, presumably via PDH, is converted to 3-hydroxyoctan-2-one and that it in turn can be reduced to 2,3-octanediol. We now extend this work using intra-striatal microdialysis to show that this reaction also occurs in rat brain. The reduction of hexanal to hexanol was also evaluated. Microdialysis probes were implanted bilaterally in the striatum and were infused with hexanal with and in the absence of added pyruvate. Analysis of microdialysis samples showed a release of 3-hydroxyoctan-2-one (9.5-10.5 pmol/min), 2,3-octanediol (2.2-2.7 pmol/min) and hexanol (64-74 pmol/min). Pyruvate addition did not increase 3-hydroxyoctan-2-one or 2,3-octanediol production. In a second series of experiments where no exogenous hexanal was infused, endogenous production of 3-hydroxyoctan-2-one (1.0-1.3 pmol/min) and 2,3-octanediol (1.0-1.2 pmol/min) was still observed, although no hexanol was detected. We also investigated the possibility that oxidative stress induced by 1-methyl-4-phenylpyridinium (MPP+) would increase lipid peroxidation resulting in increased production of 3-hydroxyoctan-2-one. Analysis of samples collected following MPP+ infusion indicated no additional increase suggesting that brief exposure to MPP+ does not increase hexanal formation over baseline levels during the experimental period.