The control of rhythmic emission of floral volatiles emitted from Rosa damascena semperflorens cv. 'Quatre Saisons' throughout floral development under various light regimes was studied. 2-Phenylethanol was the major volatile emitted in addition to monoterpenols, oxidised monoterpenols, monoterpenes and aromatic compounds. All detected volatiles were emitted rhythmically, with maximum peaks coinciding 8-10 h into a 12-h photoperiod. For some compounds a secondary, nocturnal peak was apparent. The primary and secondary maxima both occurred at approximately 24-h intervals. Rhythms appeared to be regulated endogenously: rhythmic emission continued upon exposure to continuous light or continuous darkness, and a phase shift in emission was induced upon inversion of the photoperiod. Additionally, emission continued after flower excision. A similar profile of free volatiles was stored within the floral tissue, together with glycosidic forms of 2-phenylethanol (>99% beta-D-glucoside), benzyl alcohol, citronellol and geraniol. Regression analysis indicated a significant decrease in glycosylated 2-phenylethanol through the photoperiod. These results suggest that glycosylated volatiles stored within petals may be a source of rhythmically emitted volatiles.
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http://dx.doi.org/10.1007/s00425-004-1250-5 | DOI Listing |
Alzheimers Dement
December 2024
Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, USA.
Background: Several studies link circadian rhythm disturbances to Alzheimer's disease. However, little is known about circadian rhythm involvement with Alzheimer's pathology in early stages of the disease. The current study investigates the relationship between circadian rhythms, Aβ and tau PET, and short-term memory, and explores how circadian rhythms vary between age, sex, and APOE4 status.
View Article and Find Full Text PDFEnviron Monit Assess
January 2025
Department of Environmental Sciences, Tezpur University, Tezpur, India.
PLoS One
December 2024
Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.
Monitoring the seasonal and diurnal variations in headwater stream metabolic regimes can provide critical information for understanding how ecosystems will respond to future environmental changes. In East Fork Creek, a headwater stream in middle Tennessee, week-long field campaigns were set up each month from May 2022 to May 2023 to collect stream metabolism estimators. In a more extensive field campaign from July 2-5 in 2022, diel signals were observed for temperature, pH, turbidity, and concentrations of Ca, Mg, K, Se, Fe, Ba, chloride, nitrate, DIC, DO, DOC, and total algae.
View Article and Find Full Text PDFSci Rep
December 2024
Wushan County Productivity Promotion Center, Tianshui, 741300, China.
Soil nitrogen (N) transformation is an essential portion of the N cycle in wetland ecosystems, governing the retention status of soil N by controlling the effective soil N content. N deposition produced by human activities changes the physical characteristics of soil, affecting N fractions and enzyme activities. To characterize these influences, three different N addition levels (N5, 5 g/m; N10, 10 g/m; N15, 15 g/m) were established using a wet meadow on the Qinghai-Tibet Plateau (QTP) as a control treatment (0 g/m).
View Article and Find Full Text PDFHuan Jing Ke Xue
January 2025
National Engineering Laboratory of Urban Sewage Advanced Treatment and Resource Utilization Technology, Faculty of Architecture, Civil and Transportation Engineering, Beijing University of Technology, Beijing 100124, China.
To achieve non-carbon dioxide greenhouse gas emission reduction and control in municipal wastewater treatment plants (WWTPs), this study conducted one-year long-term monitoring of nitrous oxide (NO) in the anaerobic-anoxic-aerobic (AO) process of a large-scale municipal wastewater treatment plant in Beijing. The experimental results showed that the anaerobic and anoxic zones of the AO process could effectively remove dissolved NO contained in the return sludge, while the aerobic zone was the main area for NO generation and emission, and its generation pathway may have been dominated by ammonia oxidizing bacteria (AOB) denitrification. A significant difference was observed between winter and summer NO production, and the difference in the average NO release flux was up to 7.
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