3 research outputs found
Caenorhabditis elegans as a Promising Model Organism in Chronobiology
Circadian rhythms represent an adaptive feature, ubiquitously found in nature, which grants living beings the ability to anticipate daily variations in their environment. They have been found in a multitude of organisms, ranging from bacteria to fungi, plants, and animals. Circadian rhythms are generated by endogenous clocks that can be entrained daily by environmental cycles such as light and temperature. The molecular machinery of circadian clocks includes a transcriptional-translational feedback loop that takes approximately 24 h to complete. Drosophila melanogaster has been a model organism of choice to understand the molecular basis of circadian clocks. However, alternative animal models are also being adopted, each offering their respective experimental advantages. The nematode Caenorhabditis elegans provides an excellent model for genetics and neuro-behavioral studies, which thanks to its ease of use and manipulation, as well as availability of genetic data and mutant strains, is currently used as a novel model for circadian research. Here, we aim to evaluate C. elegans as a model for chronobiological studies, focusing on its strengths and weaknesses while reviewing the available literature. Possible zeitgebers (including light and temperature) are also discussed. Determining the molecular bases and the neural circuitry involved in the central pacemaker of the C. elegans’ clock will contribute to the understanding of its circadian system, becoming a novel model organism for the study of diseases due to alterations of the circadian cycle.</p
Caenorhabditis elegans as a Promising Model Organism in Chronobiology
Circadian rhythms represent an adaptive feature, ubiquitously found in nature, which grants living beings the ability to anticipate daily variations in their environment. They have been found in a multitude of organisms, ranging from bacteria to fungi, plants, and animals. Circadian rhythms are generated by endogenous clocks that can be entrained daily by environmental cycles such as light and temperature. The molecular machinery of circadian clocks includes a transcriptional-translational feedback loop that takes approximately 24 h to complete. Drosophila melanogaster has been a model organism of choice to understand the molecular basis of circadian clocks. However, alternative animal models are also being adopted, each offering their respective experimental advantages. The nematode Caenorhabditis elegans provides an excellent model for genetics and neuro-behavioral studies, which thanks to its ease of use and manipulation, as well as availability of genetic data and mutant strains, is currently used as a novel model for circadian research. Here, we aim to evaluate C. elegans as a model for chronobiological studies, focusing on its strengths and weaknesses while reviewing the available literature. Possible zeitgebers (including light and temperature) are also discussed. Determining the molecular bases and the neural circuitry involved in the central pacemaker of the C. elegans’ clock will contribute to the understanding of its circadian system, becoming a novel model organism for the study of diseases due to alterations of the circadian cycle.</p
Chronic circadian desynchronization of feeding-fasting rhythm generates alterations in daily glycemia, LDL cholesterolemia and microbiota composition in mice
Abstract: Introduction: The circadian system synchronizes behavior and physiology to the
24-h light– dark (LD) cycle. Timing of food intake and fasting periods provide
strong signals for peripheral circadian clocks regulating nutrient assimilation,
glucose, and lipid metabolism. Mice under 12h light:12h dark (LD) cycles exhibit
behavioral activity and feeding during the dark period, while fasting occurs at rest
during light. Disruption of energy metabolism, leading to an increase in body mass,
was reported in experimental models of circadian desynchronization. In this work,
the effects of chronic advances of the LD cycles (chronic jet-lag protocol, CJL)
were studied on the daily homeostasis of energy metabolism and weight gain.
Methods: Male C57 mice were subjected to a CJL or LD schedule, measuring
IPGTT, insulinemia, microbiome composition and lipidemia.
Results: Mice under CJL show behavioral desynchronization and feeding activity
distributed similarly at the light and dark hours and, although feeding a similar daily
amount of food as compared to controls, show an increase in weight gain. In addition,
ad libitum glycemia rhythm was abolished in CJL-subjected mice, showing similar blood
glucose values at light and dark. CJL also generated glucose intolerance at dark in an
intraperitoneal glucose tolerance test (IPGTT), with increased insulin release at both light
and dark periods. Low-density lipoprotein (LDL) cholesterolemia was increased under
this condition, but no changes in HDL cholesterolemia were observed. Firmicutes/
Bacteroidetes ratio was analyzed as a marker of circadian disruption of microbiota
composition, showing opposite phases at the light and dark when comparing LD vs. CJL.
Discussion: Chronic misalignment of feeding/fasting rhythm leads to metabolic
disturbances generating nocturnal hyperglycemia, glucose intolerance and
hyperinsulinemia in a IPGTT, increased LDL cholesterolemia, and increased
weight gain, underscoring the importance of the timing of food consumption
with respect to the circadian system for metabolic health