Showing items related by title, author, creator and subject.

• A clock shock: mouse CLOCK is not required for circadian oscillator function

  DeBruyne, Jason P.; Noton, Elizabeth; Lambert, Christopher M.; Maywood, Elizabeth S.; Weaver, David R.; Reppert, Steven M. (2006-05-04)

  The circadian clock mechanism in the mouse is composed of interlocking transcriptional feedback loops. Two transcription factors, CLOCK and BMAL1, are believed to be essential components of the circadian clock. We have used the Cre-LoxP system to generate whole-animal knockouts of CLOCK and evaluated the resultant circadian phenotypes. Surprisingly, CLOCK-deficient mice continue to express robust circadian rhythms in locomotor activity, although they do have altered responses to light. At the molecular and biochemical levels, clock gene mRNA and protein levels in both the master clock in the suprachiasmatic nuclei and a peripheral clock in the liver show alterations in the CLOCK-deficient animals, although the molecular feedback loops continue to function. Our data challenge a central feature of the current mammalian circadian clock model regarding the necessity of CLOCK:BMAL1 heterodimers for clock function.
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  Risk of Recurrent Falls after Indoor and Outdoor Falls in the Elderly

  Li, Wenjun; Kang, Hyung-Joo; Procter-Gray, Elizabeth; Procter-Gray, Elizabeth; Hannan, Marian T.; Lipsitz, Lewis A. (2014-05-20)

  Background: Falls are the most common and serious health problems of the elderly. The primary goal of the study is to determine whether risk for recurrent indoor and outdoor falls differ by type of previous falls and by gender. Method: We analyzed data on falls collected in the MOBILIZE Boston prospective cohort study of community-dwelling women and men aged 65 years or older. The participants were followed for up to 4.3 years (median=2.3y). Logistic regression models, clustered by participant, were performed to estimate the probability of a subsequent indoor or outdoor fall after any fall, indoor fall, and outdoor fall. Natural log transformed time since the most recent any fall, time since the most recent indoor fall, and time since the most recent outdoor fall were used to predict probabilities of a subsequent fall of each type. Result: Among 502 participants who reported at least one fall during the follow-up, 330 had at least one reccurent fall during the follow-up period. Men and women differed in their tendencies to fall recurrently as well as in their response to an outdoor fall. Median time to the recurrent any fall since the most recent any fall was 9 weeks (IQR=22) for men and 17 weeks (IQR=30) for women [p= Conclusion: Falls, especially outdoor falls, may have different implications for the subsequent fall risks of men vs. women. Further study should examine whether outdoor falls may be an indicator of robustness for elderly women but for frailty in elderly men.
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  Selective Bacterial Community Enrichment between the Pitcher Plants Sarracenia minor and Sarracenia flava

  Yourstone, Scott M; Weinstein, Ilon; Ademski, Elizabeth; Shank, Elizabeth A; Stasulli, Nikolas M (2021-11-24)

  The interconnected and overlapping habitats present in natural ecosystems remain a challenge in determining the forces driving microbial community composition. The cuplike leaf structures of some carnivorous plants, including those of the family Sarraceniaceae, are self-contained ecological habitats that represent systems for exploring such microbial ecology questions. We investigated whether Sarracenia minor and Sarracenia flava cultivate distinct bacterial communities when sampled at the same geographic location and time. This sampling strategy eliminates many abiotic environmental variables present in other studies that compare samples harvested over time, and it could reveal biotic factors driving the selection of microbes. DNA extracted from the decomposing detritus trapped in each Sarracenia leaf pitcher was profiled using 16S rRNA amplicon sequencing. We identified a surprising amount of bacterial diversity within each pitcher, but we also discovered bacteria whose abundance was specifically enriched in one of the two Sarracenia species. These differences in bacterial community representation suggest some biotic influence of the Sarracenia plant on the bacterial composition of their pitchers. Overall, our results suggest that bacterial selection due to factors other than geographic location, weather, or prey availability is occurring within the pitchers of these two closely related plant species. This indicates that specific characteristics of S. minor and S. flava may play a role in fostering distinct bacterial communities. These confined, naturally occurring microbial ecosystems within Sarracenia pitchers may provide model systems to answer important questions about the drivers of microbial community composition, succession, and response to environmental perturbations. IMPORTANCE This study uses amplicon sequencing to compare the bacterial communities of environmental samples from the detritus of the leaf cavities of Sarracenia minor and Sarracenia flava pitcher plants. We sampled the detritus at the same time and in the same geographic location, eliminating many environmental variables present in other comparative studies. This study revealed that different species of Sarracenia contain distinct bacterial members within their pitchers, suggesting that these communities are not randomly established based on environmental factors and the prey pool but are potentially enriched for by the plants' chemical or physical environment. This study of these naturally occurring, confined microbial ecosystems will help further establish carnivorous pitcher plants as a model system for answering important questions about the development and succession of microbial communities.