4,002 research outputs found
FLOWERING LOCUS C -dependent and -independent regulation of the circadian clock by the autonomous and vernalization pathways
Background
The circadian system drives pervasive biological rhythms in plants. Circadian clocks integrate endogenous timing information with environmental signals, in order to match rhythmic outputs to the local day/night cycle. Multiple signaling pathways affect the circadian system, in ways that are likely to be adaptively significant. Our previous studies of natural genetic variation in Arabidopsis thaliana accessions implicated FLOWERING LOCUS C (FLC) as a circadian-clock regulator. The MADS-box transcription factor FLC is best known as a regulator of flowering time. Its activity is regulated by many regulatory genes in the "autonomous" and vernalization-dependent flowering pathways. We tested whether these same pathways affect the circadian system.
Results
Genes in the autonomous flowering pathway, including FLC, were found to regulate circadian period in Arabidopsis. The mechanisms involved are similar, but not identical, to the control of flowering time. By mutant analyses, we demonstrate a graded effect of FLC expression upon circadian period. Related MADS-box genes had less effect on clock function. We also reveal an unexpected vernalization-dependent alteration of periodicity.
Conclusion
This study has aided in the understanding of FLC's role in the clock, as it reveals that the network affecting circadian timing is partially overlapping with the floral-regulatory network. We also show a link between vernalization and circadian period. This finding may be of ecological relevance for developmental programing in other plant species
Age-Related Success with Elective Single versus Double Blastocyst Transfer
Background. Although the optimal outcome of assisted reproductive technology (ART) is a healthy singleton pregnancy, the rate of twin gestation from ART in women over the age of 35 is persistently high. Methods/Findings. We compared clinical pregnancy rates (PRs), ongoing pregnancy/live birth rates, and multiple gestation rates (MGRs) in 108 women who chose elective single blastocyst transfer (eSBT) to 415 women who chose elective double blastocyst transfer (eDBT) at a hospital-based IVF center. There was no significant difference in PR between eSBT and eDBT (57.4% versus 50.2%, P = 0.47) nor between eSBT and eDBT within each age group: <35, 35–37, 38–40, and >40. The risk of multiple gestations, however, was greatly increased between eSBT and eDBT (1.6 versus 32.4%, P < 0.00005), and this difference did not vary across age groups. Conclusion(s). Women undergoing eDBT are at uniformly high risk of multiple gestation regardless of age. eSBT appears to significantly lower the risk of multiple gestation without compromising PR
Use of the Montreal Cognitive Assessment (MoCA) in a Rural Outreach Program for Military Veterans
The Montreal Cognitive Assessment (MoCA) is a free, easily accessible screener ideal for rural areas where resources are limited. We examined administration and scoring by Veteran Community Outreach Health Workers (VCOHWs); compared positive screening rates using two cutoff scores; and examined predictors of education-adjusted scores in N = 168 rural military Veterans from the Alabama Veteran Rural Health Initiative. Accuracy of administration (95 percent) and scoring (68 percent) was calculated and recommendations are offered. Higher than expected rates of positive screens were observed (40 percent using 24/30 cutoff) in this relatively young (M = 55 years) community-dwelling sample. Age, education, and race but not subjective health predicted differences in domain and total education-adjusted scores on multivariate and univariate tests. This study advances social science research in rural communities by being the first to: (1) examine MoCA scores in a rural, Deep South U.S. sample; and (2) report fidelity administration data for VCOHWs
Data integration methodology that couples novel bioreactor monitoring tools, automated sampling, and applied mathematics to redefine bioproduction processes
International audienc
Quantum Chaotic Scattering in Microwave Resonators
In a frequency range where a microwave resonator simulates a chaotic quantum
billiard, we have measured moduli and phases of reflection and transmission
amplitudes in the regimes of both isolated and of weakly overlapping resonances
and for resonators with and without time-reversal invariance. Statistical
measures for S-matrix fluctuations were determined from the data and compared
with extant and/or newly derived theoretical results obtained from the
random-matrix approach to quantum chaotic scattering. The latter contained a
small number of fit parameters. The large data sets taken made it possible to
test the theoretical expressions with unprecedented accuracy. The theory is
confirmed by both, a goodness-of-fit-test and the agreement of predicted values
for those statistical measures that were not used for the fits, with the data
Diagnosis and treatment of acute sinusitis in the primary care setting: A retrospective cohort
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113710/1/lary25363.pd
Herbivory and time since flowering shape floral rewards and pollinator-pathogen interactions
Herbivory can induce chemical changes throughout plant tissues including flowers, which could affect pollinator-pathogen interactions. Pollen is highly defended compared to nectar, but no study has examined whether herbivory affects pollen chemistry. We assessed the effects of leaf herbivory on nectar and pollen alkaloids in Nicotiana tabacum, and how herbivory-induced changes in nectar and pollen affect pollinator-pathogen interactions. We damaged leaves of Nicotiana tabacum using the specialist herbivore Manduca sexta and compared nicotine and anabasine concentrations in nectar and pollen. We then pooled nectar and pollen by collection periods (within and after one month of flowering), fed them in separate experiments to bumble bees (Bombus impatiens) infected with the gut pathogen Crithidia bombi, and assessed infections after seven days. We did not detect alkaloids in nectar, and leaf damage did not alter the effect of nectar on Crithidia counts. In pollen, herbivory induced higher concentrations of anabasine but not nicotine, and alkaloid concentrations rose and then fell as a function of days since flowering. Bees fed pollen from damaged plants had Crithidia counts 15 times higher than bees fed pollen from undamaged plants, but only when pollen was collected after one month of flowering, indicating that both damage and time since flowering affected interaction outcomes. Within undamaged treatments, bees fed late-collected pollen had Crithidia counts 10 times lower than bees fed early-collected pollen, also indicating the importance of time since flowering. Our results emphasize the role of herbivores in shaping pollen chemistry, with consequences for interactions between pollinators and their pathogens
Oxygen Tomography by Čerenkov-Excited Phosphorescence during External Beam Irradiation
The efficacy of radiation therapy depends strongly on tumor oxygenation during irradiation. However, current techniques to measure this parameter in vivo do not facilitate routine monitoring in patients. Herein, we demonstrate a noninvasive method for tomographic imaging of oxygen partial pressure (pO2 ) in deep tissue using the phosphorescence decay of an oxygen-sensitive probe excited by Čerenkov radiation induced by external beam radiotherapy. Tissue-simulating scattering phantoms (60 mm diameter with a 20 mm anomaly) containing platinum(II)-G4 (PtG4), a dendritic porphyrin-based phosphor, whose phosphorescence is quenched in the presence of oxygen, were irradiated with a clinical linear accelerator. The emitted phosphorescence was measured at various positions on the phantom boundary using a spectrograph coupled to an intensified charge-coupled device (ICCD). At each position, PtG4 phosphorescence decay curves were measured by synchronizing the ICCD to the linear accelerator pulses. Tomographic images of phosphorescence yield and lifetime were recovered for phantoms with homogenous PtG4 concentrations and heterogeneous pO2 . Since PtG4 lifetime is strongly and predictably dependent on pO 2 through the Stern-Volmer relationship, tomographic images of pO 2 were also reported, and showed excellent agreement with independent oxygenation measurements. Translating this approach to the clinic could facilitate direct sensing of pO2 during radiotherapy
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