Circadian clocks are endogenous time keeping mechanisms that are ubiquitous among animals. They enable coordination of many essential biological and metabolic processes in relation to the 24 hour light cycle on earth. However, there are many habitats on earth that are not subject to this light cycle. This study aims to look at the potential genetic drift of the circadian rhythm of a subterranean spider, Meta ovalis, as well as gathering general natural history information on this under-studied spider. This study will fill general gaps in knowledge of this spider and its habitat, highlight the importance of studying organisms within a subterranean environment, and place importance on cave conservation and acquiring knowledge of these specialized, and sensitive species. This study integrates circadian and foraging theory to evaluate species as circadian specialists and generalists based on how narrowly or widely their activity is spread over the 24 h cycle. We suggest that M. ovalis benefits from a generalist strategy, showing small bursts of focused activity widely dispersed across the 24 h cycle, allowing it to capture prey opportunistically whenever it is available. Live spiders were collected from area caves, monitored in an environment controlled for light and temperature, and returned to their cave of origin. The activity of each spider was analyzed for differences in circadian activity among and between populations to determine if there is a significant drift of the circadian strategy between isolated populations of Meta ovalis. We expect to see a different circadian strategy implemented between populations due to drift from the spiders being isolated from other populations.

Adipose tissue secretes many important biologically active proteins called adipokines. A subset of adipokines, called C1q tumor necrosis factor (TNF) related proteins (CTRPs), play a key role in metabolism, inflammation, and cell signaling. C1q TNF Related Protein 3 (CTRP3) increases hepatic fatty acid oxidation, decreases inflammation, and aids in cardiovascular recovery following a myocardial infarction. However, the mechanisms behind CTRP3’s protective effects on organ systems are unknown. This exploratory study aims to analyze the circulating oligomeric state of CTRP3 and the circadian regulation of CTRP3 to help understand the role of CTRP3 in preventing disease. METHODS: For analysis of the oligomeric state of CTRP3 non-fasting mouse serum was collected from high fat fed hyper-glycemic mice or low fat fed normoglycemic mice and was separated by size exclusion filtration. For analysis of the circadian regulation of CTRP3 serum samples were collected from mice at 4 different time points (2 dark cycle and 2 light cycle) throughout the day and circulating CTRP3 levels were analyzed by immunoblot analysis. RESULTS: In both high fat and low fat fed mice CTRP3 was found to circulate in both >300 kDa oligomers and >100kDa oligomers, with no detectable amount of CTRP3 less 100 kDa. Interestingly, although there was no difference in the total amount of CTRP3 between the high fat and low fat fed mice there was a higher abundance of CTRP3 >300 kDa in the high fat fed and a greater abundance of CTRP3 found 100-300 kDa. Additionally, we found that serum CTRP3 levels vary greatly throughout a 24-hour time-period within each mouse, but no consensus circadian pattern was observed. CONCLUSION: In vitro mammalian produced recombinant CTRP3 protein was found to exist as trimer, hexamer, and high molecule weight. This is the first study to indicate that CTRP3 circulates in different oligomeric states in vivo, and this is also the first study to observe a difference in the oligomeric state of CTRP3 related to metabolic state. Combined these findings indicate that oligomeric state of CTRP3 may be more metabolically relevant than total amount of circulating CTRP3. In addition, our finding of a high variability of CTRP3 within the same mouse at different times throughout the day indicates that is not regulated by circadian rhythms but is susceptible to variability due to some unknown regulatory factor. These findings have identified novel unknown aspects of CTRP3, which require further research to understand the role of CTRP3 in human health and disease.

Whereas circadian rhythms in humans and many other organisms are closely linked to the solar day and even slight deviations could cause significant health problems, several spider species thrive despite extremely shortened or extended circadian clocks. These naturally occurring clocks influence a variety of behaviors, which may help spiders maintain a precarious balance between their conflicting roles as predator and prey. The southern black widow, Latrodectus mactans, is primarily nocturnal in its locomotor activity, but this activity appears only loosely regulated by its circadian clock. This study attempts to determine how internal circadian oscillators affect other aspects of black widow behavior, since preliminary data suggest that they also possess potentially irregular circadian patterns. The behavioral patterns of twenty female black widows were recorded over a span of several weeks. Approximately 3,400 hours of footage in standard (12-hour light-dark cycles) and constant conditions (complete darkness) were analyzed and specific behaviors were recorded using the software BORIS. This study focused on three specific sets of behavior: foraging versus retreat patterns, general activity levels throughout a 24-hr period, and waste disposal. Predation stimuli were also introduced during each cycle set to determine how the widows’ responses were affected by their internal circadian oscillators. Free-run behaviors (behavior no longer entrained to the standard 24hr cycle) observed during the dark-dark cycles differed from the behavior observed during light-dark cycles in both frequency and duration of actions, particularly those related to foraging or web work. Likewise, certain behaviors and prey avoidance techniques observed during light-cycle periods were not observed during constant conditions. This experiment examines several previously unstudied black widow behaviors for generating a better understanding on how they act in natural conditions and to determine how their actions may be influenced by their highly unusual circadian rhythms. Ultimately, this experiment will contribute to a larger, ongoing study investigating circadian-controlled behaviors and rhythms in spiders.

Doctor of Philosophy / Humans and all mammals have an internal timekeeping mechanism named the circadian clock that enables anticipation and response to the approximately 24-hour solar day and other environmental conditions. The circadian clock is self-sustained and coordinates rhythmic physiological functions such as the sleep/wake cycle, body temperature, hormone production, and metabolism, together forming the organism's "circadian rhythm." Chronic disruption of the circadian rhythm is known to be carcinogenic , but the molecular explanation for this phenomenon remains elusive. The purpose of my dissertation work was to investigate the role of mutations commonly associated with cancer as a potential molecular mechanism of circadian clock dysfunction. The PER2 gene produces the PER2 protein, which our laboratory has previously shown to interact with p53, a key "tumor suppressor" that responds to DNA damage. When not functional, these tumor suppressors can lead to uncontrolled cell division and eventually cancer. We focused on a mutation in p53 that changes p53's function and its interaction with PER2 in a manner that also prevents PER2 from functioning normally within the circadian clock. This dual dysregulation leads to the loss of rhythmic clock gene expression, and in turn, changes to cellular fitness, metabolism, and proliferation.

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Shi, Yujian. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 83-101). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

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Thesis (M.Sc.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 87-115). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: LINK NOT YET AVAILABLE.

Unicellular freshwater cyanobacterium Synechococcus elongatus PCC 7942 is the model organism for studying the circadian clock in cyanobacteria. Despite tremendous work over the last decade in identification of clock-related loci and elucidation of molecular mechanisms of the central oscillator, many details of the basic steps in generating circadian rhythms of biological processes remain unsolved and many components are still missing. A transposon-mediated mutagenesis and sequencing strategy has been adopted to disrupt essentially every locus in the genome so as to identify all of the loci that are involved in clock function. The complete genome sequence has been determined by a combination of shotgun sequences and transposon-mediated sequences. The S. elongatus PCC 7942 genome is 2,695,903 bp in length, and has a 55.5% GC content. Automated annotation identified 2,856 protein-coding genes and 51 RNA coding loci. A system for community refinement of the annotation was established. Organization and characteristic features of the genome are discussed in this dissertation. More than 95% of the PCC 7942 genome has been mutagenized and mutants affected in approximately 30% of loci have been screened for defects in circadian function. Approximately 70 new clock loci that belong to different functional categories have been discovered through a team effort. Additionally, functional analysis of insertion mutants revealed that the Type-IV pilus assembly protein PilN and the RNA chaperon Hfq are involved in transformation competence of S. elongatus cells. Functional analysis of an atypical short period kaiA insertional mutant showed that the short period phenotype is caused mainly by the truncation of KaiA by three amino acid residues. The interaction between KaiC and the truncated KaiA is weakened as shown by fluorescence anisotropy analysis. Deletion analysis of pANL, the large endogenous plasmid, implies that two toxin-antitoxin cassettes were responsible for inability to cure cells of this plasmid. In summary, the results indicate that this functional genomics project is very promising toward fulfilling our goal to assemble a comprehensive view of the cyanobacterial circadian clock. The mutagenesis reagents and dataset generated in this project will also benefit the greater scientific community.

Thesis (M. Sc.)--York University, 2001. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 128-145). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ66409.