1,901 publications found
Sort by
Photoperiod affects oxidative stress in the liver of Cricetulus barabensis through the Nrf2-Keap1 signaling pathway

ABSTRACT Changes in photoperiod affect both oxidative stress (OS) levels and antioxidant enzyme activities in animals. The liver accounts for a vital body metabolic organ. Different light durations may produce different outcomes in terms of OS and liver antioxidant pathways, but the underlying mechanism is not yet understood. This study investigated the effects of diverse photoperiods (SD, short day; MD, moderate day; LD, long day) on OS degree (H2O2 and MDA), antioxidant enzyme activities (superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GPx]), liver total antioxidant capacity, and the Nrf2-Keap1 signaling pathway in striped dwarf hamsters (Cricetulus barabensis) livers. Our results showed that (1) SD treatment for 8 weeks increased the levels of phosphorylated Nrf2, upregulated the Nrf2-Keap1 signaling pathway, and increased the protein expression of SOD and GPx, while decreasing the MDA concentration, all of which reduced the OS degree. (2) Additionally, LD treatment for 8 weeks reduced the extent of Nrf2 phosphorylation, resulting in downregulation of the Nrf2-Keap1 pathway, thus reducing protein expression of SOD2 and CAT, increasing the concentrations of H2O2 and MDA, and increasing OS degree. Collectively, OS levels in C. barabensis liver decreased during SD but increased during LD.

Darkness at night during the new moon period alters the expression levels of the clock genes in the brain of a moon-related spawner, the Malabar grouper Epinephelus malabaricus

ABSTRACT Some fish in tropical and subtropical waters exhibit moon-related rhythmicity in their reproduction and migration. We investigated the involvement of the subtypes of cryptochrome (mgCry) in moon-related rhythmicity of the Malabar grouper Epinephelus malabaricus, which spawns around the new moon period. Under natural photoperiodic conditions, the levels of mgCry1 and mgCry2 showed daily variation with peaks at 11:00 and 19:00, respectively, in the diencephalon (including the pituitary), regardless of the moon phase. The weekly changes in mgCry2, but not mgCry1, were moon-dependent, with higher levels around the new moon. When fish were reared under natural moonlight, mgCry2 in the pituitary was higher at 15:00 and 11:00 during the new moon period than the full moon period. Rearing fish under moonlight-exposed or moonlight-blocked conditions resulted in increases in mgCry genes in the pituitary during the night at full moon, suggesting that the pituitary is a target organ of the moonlight-dependent clock system. These findings indicate that mgCry genes in the brain of the Malabar grouper exhibits moon dependency, with changes according to the duration of darkness at night. We conclude that weekly changes in Cry genes in the brain play a role in entraining moon-dependent events in the Malabar grouper.

Open Access
Impact of training-shift change on chronotype and social jetlag: a longitudinal study on dancers

ABSTRACT Variations in circadian phase are expected after extreme changes of regular schedules. We took advantage of a real-life model of dance students to address the influence of social pressures on chronotype and sleep patterns in a paired longitudinal study. Seventeen dancers (18–27 years old) being trained at the Uruguayan national dance school ENFA-SODRE switched from training in the night shift in 2019 to the morning shift in 2021 and were evaluated using the Munich Chronotype Questionnaire. Dancers showed a significant advance in their chronotype (07:08 ± 01:39 to 05:12 ± 00:56, p = 0.043) and a significant increase in social jetlag (1.71 ± 1.05 to 2.46 ± 0.80, p = 0.027), while sleep duration fell within the recommended range for the age in both the night shift and the morning shift. The change in chronotype is correlated with the change in social disruption (n = 12, p = 0.038, R2 = 0.36). Dancers alternately used the strategy of oversleeping on free days (associated with higher SJL) or advancing their chronotype (with slight or no change in SJL). Analyzing the effects at the individual level, we were able to highlight the plasticity of the circadian system to cope with the impact of the morning training schedule within non-sedentary late young adults who abruptly, but permanently, changed the timing of their dance training.

Time of day affects the tolerance distinction of sugarcane varieties to water deficiency through physiological traits

ABSTRACT Water deficiency is one of the most limiting abiotic factors to sugarcane world production (Saccharum spp.). Data on chlorophyll content and gas exchange are used to select genotypes tolerant to water deficit. However, these variables are influenced by environmental factors, which vary intensely throughout the day. Thus, this research aimed to evaluate the influence of diurnal variation of gas exchange, leaf water potential, chlorophyll content, and SPAD index on the differentiation between genotypes tolerant and susceptible to water deficiency. The greenhouse experiment was conducted in a completely randomized 2 × 2 × 4 factorial scheme, with two varieties (RB867515/RB855453), two soil water tensions [without water deficiency (–D) and with water deficiency (+D)], and four evaluation times (7 am, 10 am, 1 pm, and 4 pm) with four replicates. RB867515 maintained greater CO2 assimilation, stomatal conductance, transpiration rate, intrinsic transpiration efficiency, leaf water potential, total chlorophyll content, and SPAD index under +D, regulating carbon gain about water loss and providing greater shoot biomass under +D compared to RB855453. The best times to perform the measurements for selecting tolerant genotypes based on physiological traits and specifically on the SPAD index are at 10 am and between 7 am and 10 am, respectively.