Circadian Influences on Brain Lipid Metabolism and Neurodegenerative Diseases. Metabolites Circadian rhythms are intrinsic, 24 h cycles that regulate key physiological, mental, and behavioral processes, including sleep-wake cycles, hormone secretion, and metabolism. These rhythms are controlled by the brain's suprachiasmatic nucleus, which synchronizes with environmental signals, such as light and temperature, and consequently maintains alignment with the day-night cycle. Molecular feedback loops, driven by core circadian "clock genes", such as Clock, Bmal1, Per, and Cry, are essential for rhythmic gene expression; disruptions in these feedback loops are associated with various health issues. Dysregulated lipid metabolism in the brain has been implicated in the pathogenesis of neurological disorders by contributing to oxidative stress, neuroinflammation, and synaptic dysfunction, as observed in conditions such as Alzheimer's and Parkinson's diseases. Disruptions in circadian gene expression have been shown to perturb lipid regulatory mechanisms in the brain, thereby triggering neuroinflammatory responses and oxidative damage. This review synthesizes current insights into the interconnections between circadian rhythms and lipid metabolism, with a focus on their roles in neurological health and disease. It further examines how the desynchronization of circadian genes affects lipid metabolism and explores the potential mechanisms through which disrupted circadian signaling might contribute to the pathophysiology of neurodegenerative disorders. 10.3390/metabo14120723

Clock-Sleep Communication. Current molecular medicine Rhythmicity is a characteristic feature of the inanimate universe. The organization of biological rhythms in time is an adaptation to the cyclical environmental changes brought on by the earth's rotation on its axis and around the sun. Circadian (L. Circa = "around or approximately"; diem = "a day") rhythms are biological responses to the geophysical light/dark (LD) cycle in which an organism adjusts to alterations in its internal physiology or external environment as a function of the time of day. Sleep has been considered a biological rhythm. Normal human sleep, an essential physiologic process, comprises two distinct phases: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. A mature adult human's sleep/wake cycle displays a circadian rhythm with a ~24-hour cycle. According to the two-process model of sleep regulation, the human sleep/wake cycle is orchestrated by circadian and homeostatic processes. Sleep homeostasis (a sleep-dependent process) and circadian rhythm (a sleep-independent process) are two biological processes controlling the sleep/wake cycle. There are also ultradian (< 24-hour) rhythms, including the NREM-REM sleep cycle, which has been extensively studied. The clock and sleep genes both influence sleep. In this overview, we have reviewed the circadian genes and their role in regulating sleep. Besides, the gene expression and biological pathways associated with sleep and circadian rhythm-associated diseases also have been highlighted. 10.2174/0115665240305615240630113434

Pollination Across the Diel Cycle: A Global Meta-Analysis. Ecology letters The daily transition between day and night, known as the diel cycle, is characterised by significant shifts in environmental conditions and biological activity, both of which can affect crucial ecosystem functions like pollination. Despite over six decades of research into whether pollination varies between day and night, consensus remains elusive. We compiled the evidence of diel pollination from 135 studies with pollinator exclusion experiments involving 139 angiosperms. We used phylogenetic multi-level meta-analysis to test the influence of environmental conditions and plant functional traits on diel pollination differences. Our synthesis revealed an overall lack of difference in pollination between day and night; many plant species (90% of studied spp.) exhibit similar pollination success across the diel cycle. Diel pollination differences were partially explained by elevation: nocturnal pollination success was greater at low elevations, whereas diurnal pollination was more beneficial at higher elevations. Furthermore, floral traits related to pollinator attraction (odour, colour) and anthesis time influenced diel pollination differences. In the light of increasing anthropogenic pressures on biodiversity, as well as unique challenges for nocturnal biota, this synthesis underscores the diel complementarity of pollinators for many flowering plants and the importance of considering both nocturnal and diurnal pollinators in agricultural and conservation contexts. 10.1111/ele.70036