The circadian rhythms are not solely regulated by photoperiod but are also influenced by feed regimen. Therefore, maternal nutrient restriction during gestation could potentially impact the fetal circadian rhythm. Melatonin, a circadian rhythm modulator hormone, has shown to act as an antioxidant reducing reactive oxygen species during stress exposure; and two potential mechanisms have been proposed for melatonin causing vasoconstriction and vasodilation regulating blood flow. In livestock species, nutrient restriction during gestation reduces uterine blood flow, limiting nutrients availability to the fetus for growth and development. Therefore, this project aimed to use beef heifers to evaluate the maternal nutrient restriction and/ or melatonin supplementation in (1) temporal transcript abundance of clock genes, angiogenic factors and nutrient sensing genes in bovine placenta, (2) temporal alterations of uteroplacental blood flow, vaginal temperatures, and placentome vascularization, and (3) fetal morphometrics. Early maternal nutrient restriction did not alter placental explants gene expression. Furthermore, the maternal portion of the placentome exhibited limit temporal variation, while the fetal tissue exhibited a clear temporal rhythm in the mRNA relative abundance of the genes measured. Additionally, melatonin supplementation during late gestation, showed to increased uterine blood flow, reduced vaginal temperatures, and rescued fetal weights during compromised pregnancies in a season dependent manner. In conclusion, the bovine placenta exhibited an autonomous circadian rhythm, while the fetal and maternal circadian rhythms appeared to be independent systems. Future research should examine the effects of melatonin supplementation in fetal organ development.

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Changes in locomotor rhythms of Mus musculus as a response to combinations of lighting and feeding cues were quantitatively assessed in this study. Time allowed for feeding was varied (3, 5, and 7 hours) to examine effect of different zeitgeber strengths on locomotor pattens. The effect of temporal light/dark cue removal on locomotor rhythms was examined in conjunction with restricted feeding regimes. The potential to use blood glucose levels as a temporal feeding cue was examined by comparing the locomotor rhythms of mice consuming either a high glucose or high starch diet. Blood glucose curves for animals under restricted feeding regimes of 1 and 5 hour lengths were determined for the two diets. Most of the locomotor activity records from animals in total darkness and a restricted feeding regime contained rhythm splitting. Only the anticipatory component of locomotor activity was synchronized by the 7 hour and 5 hour restricted feeding regimes in total darkness. Mice on a 3 hour restriction regime also exhibited a free run component in locomotor activity. The two experimental diets did not produce statistical differences in plasma glucose concentrations when animals were placed on a 5 hour restricted feeding regime in total darkness, but did when they were placed in a light/dark l2:l2 lighting cycle with a 1 hour feeding regime. The locomotor records indicated that free-running locomotor components were synchronized only by light/dark transitions, while the anticipatory component was synchronized by food presentation. The results of this study are consistent with a Two-Oscillator Model for control of activity rhythms. / Master of Science

The possibility that visual thresholds fluctuate in a circadian rhythmic (twenty-four hour) pattern was examined. Subjects were tested at 0400h, 1000h, 1600h and 2200h in a 30 minute dark adaptation procedure using a von Békésy tracking method. Two experiments were performed; the first tested cone functions with a red 1 degree monochromatic test stimulus located ten degrees nasally. There were no sex differences for the ten male and female subjects used in this study. However, there were time of day differences with higher thresholds at 1000h than at any other time. The second experiment examined both rod and cone thresholds with a heterochromatic test stimulus. Sex differences were found 'for the 10 male and 10 female subjects. The rods for males were found to exhibit significantly higher thresholds at 1000h than any other time. There were no significant differences for females. The null results for females may be due to an influence of the menstrual cycle on vision. The rod differences for males is thought to occur because of rod outer segment shedding which also has a circadian rhythm. A circadian rhythm questionnaire was administered to the subjects and it was found that morningness and vigorousness related to visual thresholds. / Master of Science

Approved for public release, distribution is unlimited / This study investigates the effects of reversing sleep-wake cycles on mood, sleep, and fatigue of the crewmembers and Air Wing 9 of the USS JOHN C. STENNIS (CVN-74). It also reviews the research conducted in sleep deprivation, circadian rhythms, shiftwork, fatigue, and mood. The effects of reversing sleep-wake cycle on mood of the crewmembers were analyzed by assessing a repeated administration of the Profile of Mood States (POMS). Mood states were monitored at three time points associated with the current work schedule (night shift vs. day shift) of the crewmembers. The results showed that younger participants were angrier than older participants on night shiftwork. The results also indicated that there was a significant interaction between repeated measures of mood states and gender. In addition, female participants reported significantly higher mood scale scores than the male participants, and topside participants were getting significantly less sleep than belowdecks participants. Given these findings, this area of research warrants further exploration. There is a significant need to educate military personnel of the effects of sleep deprivation and shiftwork on their job performance and individual health and safety. / Ensign, United States Navy

Approved for public release, distribution is unlimited / The Benefield Anechoic Facility (BAF), Edwards Air Force Base, California, is the largest anechoic military test facility in the world for testing developmental and operational electromagnetic equipment. Supervisors must often extend employees' work hours considerably in order to meet mission (i.e., test) timelines. Supervisors at the BAF currently have no accurate means of identifying when an employee's work performance is at risk of decreasing due to sleep deprivation, unbalanced circadian rhythms, and/or fatigue. Therefore, the focus of this research was to create a method for supervisors to effectively gauge the work performance levels of employees placed at risk for sleep deprivation. Thus, individual sleep data were collected for one week on eight volunteers at the BAF using assigned sleep monitoring devices known as Actigraphs. Extensive questionnaires were developed to determine volunteers' sleep pattern, demographics, and sleep history. For analysis purposes, the Fast Avoidance Scheduling Tool (FAST), based on the Sleep, Activity, Fatigue, and Task Effectiveness (SAFTE) model was used to determine how the performance level of each volunteer differed based on the amount of sleep acquired. The results demonstrated that as the week progressed and the volunteers' sleep decreased, the effectiveness of their work performance correspondingly decreased to a level where the safety of the test and the volunteers were both at risk. / Civilian, United States Air Force

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on January 6, 2010). Thesis advisor: M. Cathleen Kuehl-Kovarik. Includes bibliographical references.

The biological clock are responsible for entraining of circadian rhytms in many physiological and behavioral functions, including the activity of immune system. In mammals, the biological clock are located in the suprachiasmatic nuclei of the hypothalamus and also on the periphery. The main oscillator in suprachiamatic nuclei synchronizes the phases of the peripheral oscillators in tissues and the other brain areas and it also drives synthesis of melatonin in the pineal gland. Its endogenous period Tau (τ) is being synchronized with external 24-hour day under normal conditions, mostly by the light-dark cycles during the day and night and also by non-photic stimuli. By the application of endotoxin, disruption of normal endogenous conditions in organism causes activation of the immune response, behavioral changes and phase shifts of the circadian rhythmicity. This work examines effect of acute application endotoxin lipopolysaccharid on the cellular signaling cascades in the cells of suprachiasmatic nuclei and pineal gland. Our data indicate, that levels of phosphorylated forms of kinases GSK3β, ERK1/2 and levels of phosphorylated forms transcription factors STAT3 are substantially modificated after administration of lipopolysaccharid in the suprachiasmatic nuclei and especially in the pineal gland of...