Circadian Activity Rhythms Research Articles

Effect of the daily duration of calf contact on the dam's ultradian and circadian activity rhythms

Cow-calf contact systems are attracting increasing interest among farmers and some are already being implemented into dairy farms. However, a comprehensive assessment of animal welfare in these systems is lacking. One reason for this is the large amount of time required for behavioral observations. However, the increased use of sensors in herd management assistance systems offers new opportunities for automated monitoring of animal welfare. For example, accelerometers can be used to collect activity data for a specific pattern analysis. In this study, ultradian and circadian rhythms of cows were analyzed. The degree of functional coupling (DFC; range of values: 0–1) expresses the extent to which the activity is cyclic to 24 h, and therefore harmonically synchronized with the periodicity of the environment. A DFC of 1 indicates complete adaptation of the cows' activity rhythm to the 24-h day. Additionally, the diurnality index (DI) is used to examine the distribution of diurnal and nocturnal activity. A DI of 1 indicates complete diurnal activity, whereas −1 indicates complete nocturnal activity. The rhythms of healthy and well-adapted animals show high adaptation to the 24-h day, whereas external or endogenous effects can interfere with these rhythms. Although contact with their calves allows cows to behave more naturally, it is possible that calves demanding their mothers' attention may affect the cows' rhythmicity, similar to other external factors. To test this hypothesis, 2 herds of German Holstein cows housed in a mirrored loose housing system were included in the study, which was conducted over 2 experimental periods. Three treatments were applied, differing in contact between cow and calf. The contact dams had either whole-day or daytime contact with their calves, and the no-contact cows were separated from their calves directly postpartum. Accelerometers were used to record and analyze the cows' activity between 59 and 83 DIM, thus excluding the calving and weaning phases. Generalized linear mixed models were used to estimate the effect of treatment (no, daytime, and whole-day contact) on DFC and DI, considering the effects of estrus, deviation of milking start in the evening, and parity (primi- vs. multiparous). Finally, the harmonic period lengths of the activity patterns were extracted to analyze the distribution of the primarily expressed period lengths of the different treatments. In general, the average activity patterns of the cows did not differ between the treatments. However, dams with whole-day contact showed a lower activity peak before milking but a higher activity after evening milking. Nevertheless, the DFC and DI were similar in each group. During estrus, the chance of a maximum DFC decreased and the DI increased. Whole-day contact dams showed the most significant harmonic periods (33 per cow). Nevertheless, the primarily expressed period length (3.4 h) was equal in each treatment. In conclusion, neither contact with the calf nor its daily duration affected the ultradian and circadian rhythms of dams compared with cows separated from their calf.

Circadian Rhythms of Body Temperature and Locomotor Activity in Spontaneously Hypertensive Rats under Frequent Changes in Light Conditions.

Changes in lighting accompany modern urbanization trends and can lead to various pathologies based on circadian disturbances. In this study, we assessed the changes in the circadian rhythm of core body temperature (Tcore) and locomotor activity of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) following exposure to different lighting conditions: extended light phase of the day (16 h-8 h, 20 h-4 h, 24 h-0 h), light pollution, monochromatic light, and bright light therapy. The telemetry data was collected after experimental lighting conditions during periods with standard lighting (12 h of light and 12 h of darkness) and was processed using linear and cosinor analysis. The daily rhythms of rats' parameters persisted in accordance with the standard lighting regime. Tcore changes were observed in both groups compared to the initial period: in WKY, a decrease in Tcore during the darkness and an increase during the light; in SHR, the opposite trend, with Tcore increased during the darkness and decreased during the light phase of the day. A relationship between Tcore and activity was observed with weak correlation. WKY exhibited more pronounced signs of adaptive variation and desynchronization compared to SHR, which could be associated with a wider range of functional capabilities of the organism without cardiovascular pathology.

The role of melatonin deficiency induced by pinealectomy on motor activity and anxiety responses in young adult, middle-aged and old rats.

Aging affects anxiety levels in rats while the pineal gland, via its hormone melatonin, could modulate their inherited life "clock." The present study aimed to explore the impact of plasma melatonin deficiency on anxiety responses and the possible involvement of the hypothalamic-pituitary-adrenocortical (HPA) axis and heat shock proteins (Hsp) 70 and 90 in the frontal cortex (FC) and the hippocampus in young adult, middle-aged and elderly rats with pinealectomy. Melatonin deficiency induced at different life stages did not affect the lifespan of rats. Pinealectomy abolished the circadian rhythm of motor activity, measured for 48h in the actimeter, in young adult but not in middle-aged rats. Pinealectomy reduced the motor activity of the young adult rats during the dark phase and impaired the diurnal activity variations of old rats. The same generations (3- and 18month-old rats with pinealectomy) had lower anxiety levels than the matched sham groups, measured in three tests: elevated-plus maze, light-dark test, and novelty-suppressed feeding test. While the activity of the HPA axis remained intact in young adult and middle-aged rats with melatonin deficiency, a high baseline corticosterone level and blunted stress-induced mechanism of its release were detected in the oldest rats. Age-associated reduced Hsp 70 and 90 levels in the FC but not in the hippocampus were detected. Pinealectomy diminished the expression of Hsp 70 in the FC of middle-aged rats compared to the matched sham rats. Our results suggest that while melatonin hormonal dysfunction impaired the motor activity in the actimeter and emotional behavior in young adult and elderly rats, the underlying pathogenic mechanism in these generations might be different and needs further verification.

Contribution of the eye and of opn4xa function to circadian photoentrainment in the diurnal zebrafish.

The eye is instrumental for controlling circadian rhythms in mice and human. Here, we address the conservation of this function in the zebrafish, a diurnal vertebrate. Using lakritz (lak) mutant larvae, which lack retinal ganglion cells (RGCs), we show that while a functional eye contributes to masking, it is largely dispensable for the establishment of circadian rhythms of locomotor activity. Furthermore, the eye is dispensable for the induction of a phase delay following a pulse of white light at CT 16 but contributes to the induction of a phase advance upon a pulse of white light at CT21. Melanopsin photopigments are important mediators of photoentrainment, as shown in nocturnal mammals. One of the zebrafish melanopsin genes, opn4xa, is expressed in RGCs but also in photosensitive projection neurons in the pineal gland. Pineal opn4xa+ projection neurons function in a LIGHT ON manner in contrast to other projection neurons which function in a LIGHT OFF mode. We generated an opn4xa mutant in which the pineal LIGHT ON response is impaired. This mutation has no effect on masking and circadian rhythms of locomotor activity, or for the induction of phase shifts, but slightly modifies period length when larvae are subjected to constant light. Finally, analysis of opn4xa;lak double mutant larvae did not reveal redundancy between the function of the eye and opn4xa in the pineal for the control of phase shifts after light pulses. Our results support the idea that the eye is not the sole mediator of light influences on circadian rhythms of locomotor activity and highlight differences in the circadian system and photoentrainment of behaviour between different animal models.

Chronobiological approach to study microsymbiont catalase activity in female reproductive tract

Catalase is a heme-containing enzyme belonging to protection factors that destroys peroxide compounds. The presence of catalase activity is an important ability of microorganisms that allows them to be protected from unfavorable factors as well as adapt to macroorganism conditions. Catalase along with superoxide dismutase plays an important role in pathogen resistance to phagocyte oxygen-dependent bactericidal mechanisms. The aim of the study was to investigate microsymbiont catalase activity from female reproductive tract in normocenosis and candidiasis dysbiosis using the chronobiological approach. The study was conducted on clinical isolates, isolated from female reproductive tract microsymbiocenosis. The catalase activity was determined by spectrophotometry based on 24 hour-long hydrogen peroxide reduction with 3-hours interval in winter season. Dynamic hydrogen peroxide was assessed in 3–5 experiment replicates. In some Lactobacillus spp., catalase was found containing no heme group — pseudocatalase. Chronobiological approach allowed to reveal enzyme activity from all microsymbionts. The dominant and associative microbiota isolated from healthy females was characterized by circadian (24 hours) rhythms of catalase activity early in the morning — 5 a.m. (р 0.05). Hydrogen peroxide decomposes spontaneously or via non-enzymatic catalysts, and microorganisms cope with this situation under such conditions. In microsymbionts characteristic of female reproductive tract dysbiosis, and usually found in large numbers along with decreased Lactobacillus spp. ultradian rhythms with 12- and 8-hour harmonics of catalase activity with acrophase were recorded in the morning (8 a.m.) and evening hours (8 p.m.). The minimum values of enzyme production in all cultures were recorded at 12 p.m. and 5 p.m. Therefore, the contribution of the rhythm of the studied parameter at varying degree of vaginal sterility reflects the adaptive pathogen capabilities to the conditions of existence and can be the basis for studying related regulatory mechanisms. Mesor and amplitude phase stability are universal rhythmometric parameters used to evaluate patient’s condition independent of species assignment.

Circadian and sleep phenotypes in a mouse model of Alzheimer's disease characterized by intracellular accumulation of amyloid β oligomers.

Disturbances in sleep-wake and circadian rhythms may reportedly precede the onset of cognitive symptoms in the early stages of Alzheimer's disease (AD); however, the underlying mechanisms of these AD-induced sleep disturbances remain unelucidated. To specifically evaluate the involvement of amyloid beta (Aβ) oligomers in AD-induced sleep disturbances, we examined circadian and sleep phenotypes using an Aβ-GFP transgenic (Aβ-GFP Tg) mouse characterized by intracellular accumulation of Aβ oligomers. The circadian rhythm and free-running period of wheel running activity were identical between Aβ-GFP Tg and littermate wild-type mice. The durations of rapid eye movement (REM) sleep were elongated in Aβ-GFP Tg mice; however, the durations of non-REM sleep and wakefulness were unaffected. The Aβ-GFP Tg mice exhibited shifts in the electroencephalogram (EEG) power spectra toward higher frequencies in the inactive light phase. These findings suggest that the intracellular accumulation of Aβ oligomers might be associated with sleep quality; however, its impact on circadian systems is limited.

ЦИРКАДНЫЙ РИТМ В ЯЙЦЕКЛАДКЕ КУР

The paper is devoted to poultry motor activity circadian rhythms and these rhythms influence on layer production. The time of egg forming in layer oviduct is proved to be constant, that is, 24 hours. It doesn’t depend on egg laying cycle longevity. Egg laying time is determined with ovulation time. The signal to production rhythms synchronization is the time light switching on in poultry house. When light in poultry house is being switched on at the same time the ovulation beginning phase is moving towards morning hours and resulting in egg laying pause. Some egg laying rhythm asynchrony is characteristic for low productive layers. New light regimes introduction with layers biological rhythms accounting helps to increase egg production.

Role of melanocortin system in the locomotor activity rhythms and melatonin secretion as revealed by agouti-signalling protein (asip1) overexpression in zebrafish.

Temporal signals such as light and temperature cycles profoundly modulate animal physiology and behaviour. Via endogenous timing mechanisms which are regulated by these signals, organisms can anticipate cyclic environmental changes and thereby enhance their fitness. The pineal gland in fish, through the secretion of melatonin, appears to play a critical role in the circadian system, most likely acting as an element of the circadian clock system. An important output of this circadian clock is the locomotor activity circadian rhythm which is adapted to the photoperiod and thus determines whether animals are diurnal or nocturnal. By using a genetically modified zebrafish strain known as Tg (Xla.Eef1a1:Cau.asip1)iim04, which expresses a higher level of the agouti signalling protein 1 (Asip1), an endogenous antagonist of the melanocortin system, we observed a complete disruption of locomotor activity patterns, which correlates with the ablation of the melatonin daily rhythm. Consistent with this, in vitro experiments also demonstrated that Asip1 inhibits melatonin secretion from the zebrafish pineal gland, most likely through the melanocortin receptors expressed in this gland. Asip1 overexpression also disrupted the expression of core clock genes, including per1a and clock1a, thus blunting circadian oscillation. Collectively, these results implicate the melanocortin system as playing an important role in modulating pineal physiology and, therefore, circadian organisation in zebrafish.

Spatial distribution and circadian locomotor activity of invasive armored catfish (Loricariidae) in the freshwater and brackish water.

Invasive suckermouth armored catfish Pterygoplichthys spp. successfully spread during one decade into many river systems of Vietnam. Wide and rapid invasion of armored catfish might be associated with using brackish water in estuaries to spread from one river system to another. The first goal of our study was to assess the horizontal and vertical distribution of invasive fish in freshwater (Da Rang River) and in brackish water (Da Rang River estuary) associated with circadian rhythm. In the both sampling locations, fish were mainly caught at nighttime at the bottom and near the surface using the net traps and vertical nets. In estuary, fish were caught in the net traps with distance 2.0-7.5 m from the right or left banks where water was predominantly fresh. In freshwater of the Da Rang River, fish were often caught near the left bank with gravel and stone substrate. The second goal of our study was to experimentally evaluate the circadian (12 hours of the night and 12 hours of the day) rhythm of locomotor activity (LA) of fish. Fish from different freshwater locations (Am Chua canal and Da Rang River) had a similar diurnal dynamic of LA with mostly movements (77-83% of total diurnal LA) at nighttime (18:00-6:00, GMT+7) at the end of the wet season. Armored catfish from the brackish water location (Da Rang River estuary) also were mostly active (76% of total diurnal LA) overnight. However, fish from freshwater and brackish water had difference in the timing of behavioral activity. Fish LA from estuary was significantly lower than LA of fish from freshwater locations during 18:00 to 21:00 before low tide. The results of our field and experimental studies established that armored catfish in estuary moved in horizontal and vertical planes predominantly at nighttime. Tide level regulates locomotor activity of invasive fish and could influence on the possibility of their spreading through the estuary.

Circadian Rhythms of Locomotor Activity Mediated by Cryptochrome 2 and Period 1 Genes in the Termites Reticulitermes chinensis and Odontotermes formosanus.

Locomotor activity rhythms are crucial for foraging, mating and predator avoidance in insects. Although the circadian rhythms of activity have been studied in several termite species, the molecular mechanisms of circadian rhythms in termites are still unclear. In this study, we found that two termite species, R. chinensis and O. formosanus, exhibited clear circadian rhythms of locomotor activity in constant darkness along with rhythmically expressed core clock genes, Cry2 and Per1. The knockdown of Cry2 or Per1 expression in the two termite species disrupted the circadian rhythms of locomotor activity and markedly reduced locomotor activity in constant darkness, which demonstrates that Cry2 and Per1 can mediate the circadian rhythms of locomotor activity in termites in constant darkness. We suggest that locomotor activity in subterranean termites is controlled by the circadian clock.

The presence/absence of conspecifics modulates the circadian locomotor activity and body mass in spotted munia (Lonchura punctulata)

ABSTRACT Biological clocks regulate the behavior and physiology of animals by tracking the local time using diverse time cues. Social cues are relevant in studying the behavior of gregarious animals, but these cues have not been widely studied in birds. Temporal information for circadian timekeeping is socially communicated through visual, physical, olfactory, and auditory means. We examined the efficacy of pulsatile social interactions on locomotor activity and its associated characteristics such as distribution profile of rest and activity, total counts, activity duration, phase shift in activity onset, and circadian periodicity in spotted munia. Besides, we analyzed the effect of such social interactions on their body mass. Spotted munia exhibited phase shift in the onset of activity when subjected to social isolation, but these cues could not affect their circadian periodicity. In Pair as well as in Group, social isolation led to increased activity and activity duration, and decreased body mass in guests relative to the host bird. Our results suggest that the circadian rhythm of locomotor activity in spotted munia is quite sensitive to socialization and isolation, and isolation is detrimental for the birds. Consistent with these observations, the decline in body mass revealed the physiological consequences of social isolation on spotted munia.

Restless nights when sick: ectoparasite infections alter rest-activity cycles of diurnal fish hosts.

Circadian rhythms are timekeeping mechanisms responsible for an array of biological processes. Disruption of such cycles can detrimentally affect animal health. Circadian rhythms are critical in the co-evolution of host–parasite systems, as synchronization of parasite rhythms to the host can influence infection dynamics and transmission potential. This study examines the circadian rhythms in behaviour and activity of a model fish species (Poecilia reticulata) in isolation and in shoals, both when uninfected and infected with an ectoparasite (Gyrodactylus turnbulli). Additionally, the rhythmical variance of parasite activity under different light conditions as well as rhythmical variance in parasite transmissibility was explored. Overall, infection alters the circadian rhythm of fish, causing nocturnal restlessness. Increased activity of gyrodactylids on the host's skin at night could potentially contribute to this elevated host activity. Whilst migration of gyrodactylids across the host's skin may have caused irritation to the host resulting in nocturnal restlessness, the disruption in guppy activity rhythm caused by the expression of host innate immunity cannot be excluded. We discuss the wider repercussions such behavioural responses to infection have for host health, the implications for animal behaviour studies of diurnal species as well as the application of chronotherapeutic approaches to aquaculture.

Accounting for an individual approach to training of athletes in playing sports (on the example of basketball, volleyball and futsal)

The article is devoted to the study of ways to optimize the training process for student basketball, volleyball and futsal teams, taking into account the individual biorhythmic properties of female athletes. The study determines the importance of individualizing training and preparation, in particular, taking into account circadian rhythms and other biorhythmic aspects that determine physiological and psychological changes in female athletes during the day. The tasks of the study included testing the biological rhythms of female athletes to improve the training process. 36 sportswomen (14 basketball players, 12 volleyball players, 10 soccer players) of the teams of the National University of Life and Environmental Sciences of Ukraine took part in the study. The analysis of the biological rhythms of female athletes included various indicators that help to understand their physiological reactions and determine the optimal schedule of training and rest. Among them were taken: heart rate, rhythmic changes in body temperature (measurement of body temperature during the day to determine the circadian rhythm of heat exchange), rhythmic changes in blood pressure (observation of changes in blood pressure during the day to determine the circadian rhythm of cardiovascular activity), indicators of activity and sleep (determination of activity and sleep mode, including time of awakening, time of falling asleep and duration of sleep), hand strength (hand dynamometry), standing long jump. The article examines the results of the study, which include an analysis of the optimal time for training, fatigue and recovery management, adaptation of training programs to biorhythms, and the impact on psychological readiness. The conclusions drawn indicate that an individual approach to training, based on biorhythmic properties and psychomotor qualities, can improve the performance of sportswomen in the aforementioned teams. This article is aimed at coaches, scientists and physical training specialists interested in innovative methods of training female athletes aimed at taking into account their individual biorhythms to achieve optimal results in basketball, volleyball and futsal.

Association between disruption of circadian activity rhythms and obesity

ABSTRACT This cross-sectional study aimed to elucidate the association between disruption of circadian activity rhythms and obesity-related indices. This study included 69 older participants (male, n = 36; female, n = 33), and disruption of circadian activity rhythms in daily life was assessed using the cosinor method based on physical activity data. The daily physical activity data were fitted to a cosine curve to estimate the peak phase (acrophase), and the difference in the peak phase (time) for each day was determined. The standard deviation (SD) of the mean peak phase differences over 6 days was obtained. The higher the SD value, the more disturbed the circadian rhythm of activity. Based on the calculated values, the samples were divided into tertiles (small, medium, and large). A significant positive correlation was found between Log SD and body fat percentage on the disruption of circadian activity rhythms and obesity-related indices. In addition, positive associations were observed among body mass, body mass index, and Log SD. However, these associations were not observed in women. These results suggest that disruption of circadian activity rhythms is associated with obesity-related indices and may differ according to sex.

Chronobiology of free-ranging domestic cats: Circadian, lunar and seasonal activity rhythms in a wildlife corridor

Among domestic animals, the domestic cat (Felis catus) probably has the highest proportion of free-ranging individuals in the population and as such is an important component (i.e. predator) in ecosystems. Due to their potential impact on wildlife, the management of domestic cats is a hot topic today. However, there are few studies on the chronobiology and activity of domestic cats in relation to natural cycles. Therefore, the aim of our research was to investigate their circadian, lunar and seasonal rhythms. We monitored the activity of free-ranging cats in a selected corridor within an approximately 800 m2 patch of shrubs and trees in an agricultural landscape that is regularly used by wildlife in the surrounding area. Monitoring was carried out for two consecutive years using a trail camera. Data collection was based on video analysis of all recorded video clips (n = 2081 from 732 camera trap nights). A total of at least 15 individuals were identified in the area. Cats were most frequently observed in spring and summer (a total of 70% of all observations). Cats with prey were mostly observed in summer (∼56%) and never in winter. Circadian activity of domestic cats was nocturnal/crepuscular (p < 0.0001) with two peaks of activity, one in the late evening (∼21.00 h) and another in the early morning (∼5.00 h). The appearance of the cats with the prey corresponded to the general circadian activity. Slight shifts in activity due to day length (sunset/sunrise) were observed when comparing circadian rhythms in relation to seasons, especially in winter when there was a pronounced peak in activity in the early evening. For cat activity in relation to the lunar cycle, we found a tendency for higher nocturnal activity around new moon (p = 0.065), with this pattern being significant in spring (p < 0.05). However, the appearance of cats with prey was not related to the lunar cycle. Understanding the circadian, lunar and seasonal activity rhythms of domestic cats is an important prerequisite for developing an optimal cat management strategy that takes into account both welfare aspects (especially natural behaviour) and minimising the impact of domestic cats on wildlife.

Opioid infusions at different times of the day produce varying degrees of opioid-induced hyperalgesia

BackgroundOpioids are metabolised by enzymes the activities of which vary with the circadian rhythm. We examined whether opioid infusions administered at different times of the day produce varying degrees of opioid-induced hyperalgesia (OIH) in animal experiments and clinical studies. MethodsMale Sprague–Dawley rats received remifentanil infusions (1 μg kg−1·min−1 for 1 h) at Zeitgeber times (ZT) 0, 4, 8, 12, 16, or 20 h. Rhythmicity of mechanical hypersensitivity was assayed after the infusion. Mechanical hypersensitivity, drug concentration, and metabolic enzyme activity of Wistar rats that received sufentanil (10 μg kg−1; four consecutive i.p. injections at 15-min intervals) or remifentanil infusion at ZT0 or ZT8 were assayed. Sixty patients who underwent abdominal laparoscopic surgery under general anaesthesia received remifentanil infusion (0.15 μg kg−1 min−1) and sufentanil injection (0.2 μg kg−1) at induction and skin incision, respectively. Postoperative pressure pain sensitivity, pain Numeric Rating Scale (NRS), drug concentrations, and nonspecific esterase activity were assessed. ResultsSprague–Dawley rats that received remifentanil infusion exhibited a robust rhythmic paw withdrawal threshold (JTK_CYCLE: P=0.001, Q=0.001, Phase=26). Wistar rats infused with remifentanil or sufentanil at ZT8 exhibited greater OIH (P<0.001) than those infused at ZT0, with higher blood concentrations (P<0.001) and lower metabolic enzyme activities (P=0.026 and P=0.028, respectively). Patients in the afternoon group exhibited higher pressure pain sensitivity at forearm (P=0.002), higher NRS (P<0.05), higher drug concentrations (sufentanil: P=0.037, remifentanil: P=0.005), and lower nonspecific esterase activity (P=0.024) than the morning group. ConclusionsOpioid infusions administered at different times of day produced varying degrees of OIH, possibly related to circadian rhythms of metabolic enzyme activities. Clinical trial registrationNCT 05234697.

Influence of Melatonin on Maturation of Male Germ Cells.

We studied the influence of epiphysectomy and administration of melatonin to epiphysectomized outbred white rats on the level and daily dynamics of damage to the genetic material of developing male germ cells. Epiphysectomy leads to an increase in the level of damage in the DNA structure and the disappearance of the circadian rhythm of the activity of repair enzyme PARP-1 and the apoptosis-inducing enzyme caspase-3. The administration of melatonin to animals after epiphysectomy reduces the level of DNA damage, restores the circadian rhythm of activity of PARP-1 and caspase-3. These fundings suggest that melatonin can indirectly protect DNA of maturing male gametes.

The circadian activity rhythms for elderly inpatients with stroke or motor diseases in a rehabilitation facility and its relationship to physical activity level.

The online version contains supplementary material available at 10.1007/s41105-023-00488-8.

Identification of CYCLE targets that contribute diverse features of circadian rhythms in the mosquito Culex pipiens

Culex pipiens demonstrates robust circadian rhythms in adult eclosion, flight activity, mating, and development. These rhythmic patterns are believed to be controlled by the endogenous light-entrainable circadian clock that consists of positive and negative regulators working in a transcription-translation feedback loop. Moreover, these mosquitoes undergo seasonal diapause in exposure to the short photoperiod of late summer or early fall. However, the exact genetic and cellular mechanism behind the clock gene-mediated activity pattern, seasonal time measurement, and subsequent diapause initiation still need to be unraveled. To determine the possible linkage between clock genes and downstream processes, here we employed ChIP-sequencing to identify the direct targets of one of the core clock proteins, Cycle (CYC). The nearest genes with peaks mapping to their 1Kb upstream region of the transcription start site were extracted and scanned for consensus E box sequences, resulting in a dataset comprising the target genes possibly regulated by CYC. Based on the highest fold enrichment and functional relevance, we identified genes relating to five gene categories of potential interest, including peptide/receptors, neurotransmission, olfaction, immunity, and reproductive growth. Of these, we validated fourteen genes with ChIP-qPCR and qRT-PCR. These genes showed a significantly high expression in dusk compared to dawn in concert with the activity level of the CYC transcription factor and are thus strong candidates for mediating circadian rhythmicity and possibly regulating seasonal shifts in mosquito reproductive activity.

The Effects Of Time-of-day Dependent Exercise Training On Circadian Rhythms In Activity And Cardiovascular Adaptations

The Effects Of Time-of-day Dependent Exercise Training On Circadian Rhythms In Activity And Cardiovascular Adaptations