Cytokinin has strong connections to development and a growing role in the abiotic stress response. Here we show that CYTOKININ RESPONSE FACTOR 2 (CRF2) is additionally involved in the salt (NaCl) stress response. CRF2 promoter‐GUS expression indicates CRF2 involvement in the response to salt stress as well as the previously known cytokinin response. Interestingly, CRF2 mutant seedlings are quite similar to the wild type (WT) under non‐stressed conditions yet have many distinct changes in response to salt stress. Cytokinin levels measured by liquid chromatography–tandem mass spectrometry (LC‐MS/MS) that increased in the WT after salt stress are decreased in
Precisely targeted measurements of trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) reveal inter-chamber heterogeneities in specimens of the planktic foraminifer
- NSF-PAR ID:
- 10209431
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 11
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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SUMMARY crf2 , potentially from CRF2 regulation of cytokinin biosynthesis genes. Ion content measured by inductively coupled plasma optical emission spectrometry (ICP‐OES) was increased in the WT for Na, K, Mn, Ca and Mg after salt stress, whereas the corresponding Ca and Mg increases are lacking incrf2 . Many genes examined by RNA‐seq analysis were altered transcriptionally by salt stress in both the WT andcrf2 , yet interestingly approximately one‐third of salt‐modifiedcrf2 transcripts (2655) showed unique regulation. Different transcript profiles for salt stress incrf2 compared with the WT background was further supported through an examination of co‐expressed genes by weighted gene correlation network analysis (WGCMA) and principal component analysis (PCA). Additionally, Gene Ontology (GO) enrichment terms found from salt‐treated transcripts revealed most photosynthesis‐related terms as only being affected incrf2 , leading to an examination of chlorophyll levels and the efficiency of photosystem II (via the ratio of variable fluorescence to maximum fluorescence,F v/F m) as well as physiology after salt treatment. Salt stress‐treatedcrf2 plants had both reduced chlorophyll levels and lowerF v/F mvalues compared with the WT, suggesting that CRF2 plays a role in the modulation of salt stress responses linked to photosynthesis. -
Throughout the course of an organism’s life, the chemical signatures of environment, food consumption, and weather are recorded into their carbonate structures; these signatures can be directly linked to a time-resolved lifespan. Here we present trace element data from benthic foraminifera and tropical molluscs determined using an ESI NWR193UC excimer laser coupled with an Agilent 8900 triple quadrupole mass spectrometer in the MicroAnalytical Geochemistry and Isotope Characterization (MAGIC) Laboratory at the University of Maine. Benthic foraminifera are protists that live on the sea floor and produce calcite shells, progressively adding chambers. Changes in Mg/Ca in foraminifera are used as a proxy for ocean temperature. Laser ablation ICP-MS data for 18 trace elements were collected in individual growth chambers in foraminifera of the genus Uvigerina from the Bay of Plenty. Line scans were performed within thin (~10 µm) chamber walls using a spot size of 8 µm, beam energy density of 3 J/cm2, repetition rate of 12 Hz, and scan speeds of 2-3 µm/s. Concentrations were determined relative to the NIST610 glass. Ratios of Mg/Ca and other trace elements record the same range of values as those determined via bulk wet chemistry analysis of ~10 foraminifera for a given population, which suggests that LA-ICP-MS may be a viable alternative to wet chemistry. Trace element data were collected across shells of the warm-tropical mollusc species Chione subrugosa from the Ostra Base Camp area, Peru (78°37’22”W, 8°54’46”S). Previous studies of the area have suggested that a large climate transition occurred, transforming a warm water tropical bay into a desert surrounded by a coastal stand with cool waters. This area was occupied by humans at 6250-5450 radiocarbon years BP. This study examines Chione subrugosa, which were found in the living position at the fossilized Ostra Beach and are thought to have been the final living warm-tropical molluscs in the bay. Studies of modern molluscs have revealed that molluscs record massive climatic changes, such as El Niño, in their chemistry. Laser ablation provides a unique opportunity to examine chemical changes directly related to the changing coastal environment. Line scans transverse growth bands along the length of the shell, providing a high resolution record of daily variation in trace element chemistry over the lifespan of the mollusc. Eleven elements were analysed with a beam energy density of 2.4 J/cm2, repetition rate of 15 Hz, spot size of 5 x 25 µm, and a scan speed of 5 µm/s. Preliminary data suggest the preservation of yearly oscillations in trace elements, with high concentrations of La, Ce, U, and Pb during early shell growth. Continued study will examine catastrophic mollusc life events in an effort to link these with environmental climate changes over daily timescales.more » « less
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Abstract Sr‐U, a coral‐based paleothermometer, corrects for the effects of Rayleigh Fractionation on Sr/Ca by regressing multiple, paired U/Ca and Sr/Ca values. Prior applications of Sr‐U captured mean annual sea surface temperatures (SSTs), inter‐annual variability, and long‐term trends. However, because many Sr/Ca‐U/Ca pairs are needed for a single Sr‐U value as originally formulated, the temporal resolution of the proxy is typically limited to 1 year. Here, we address this limitation by applying laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS) to three
Porites colonies from Jarvis and Nikumaroro Islands in the central equatorial Pacific (CEP), generating ∼25 Sr/Ca‐U/Ca pairs per month of skeletal growth. Both Sr/Ca and U/Ca vary significantly over small (sub‐mm) length scales and support the calculation of Sr‐U values using the original regression method. Over the represented temperature range of 24–31°C, the Sr/Ca‐U/Ca‐SST relationships are nonlinear, a finding consistent with predictions of the Rayleigh model. To reflect this non‐linearity, we developed a calibration using multivariate nonlinear regression. The multivariate, three‐coral calibration was applied to 20 years of monthly resolved Sr/Ca and U/Ca of a coral interval not included in the calibration, yielding RMSE = 0.73°C andr 2 = 0.85 (p < 0.05;df = 256). The multivariate calibration performed significantly better than Sr/Ca alone (r 2 = 0.28). Applying the new calibration to a subfossilPorites from Kiritimati Atoll, CEP (2200 Before Present) yields equivalent phase and amplitude of interannual variability, but water temperatures ∼1.6°C cooler than they are in this region today. -
Home dust samples were collected from the surface of heating, ventilation, and air conditioning (HVAC) filters from eleven homes at different locations in Columbia, South Carolina, USA. Bulk metal concentrations in the dusts were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Size-based elemental distributions in the <450 nm particles were determined by asymmetrical flow-field flow fractionation (AF4) coupled to ICP-MS. The bulk Ti/Nb ratios are generally higher (up to 5609) than the natural background ratios ( e.g. , 320), indicating contamination of home dusts with TiO 2 -engineered particles. Size-based Ti/Nb ratios in the <450 nm fraction are similar to the natural background ratio, indicating a natural origin of Ti-bearing particles in this size fraction, and subsequently that anthropogenic Ti-bearing particles (TiO 2 ) are associated with particles >450 nm either due to aggregation or to their release as large particles. The concentrations of TiO 2 -engineered particles were estimated by mass balance calculations using total Ti concentrations and increases in Ti/Nb ratios above the natural background ratio. They vary between 0 and 13 300 mg TiO 2 kg −1 . The upper crustal-normalized rare earth element pattern indicates a positive La and Ce anomaly. The size of the cerium and lanthanum anomalies varies from 0.8 to 1.6 and 0.7 to 3.95, respectively, indicating contamination of several home dusts with Ce and La. The concentrations of bulk anthropogenic Ce and La were estimated based on mass balance calculations and anomaly size and varied between 0 and 5.7 ± 2.2 mg Ce kg −1 and 0 and 21.1 ± 7.4 mg La kg −1 , respectively. Size-based Ce/La ratios in the <450 nm fraction are lower than the natural background ratio, indicating contamination of this size fraction with nanosized La-bearing particles. Anthropogenic Ti and La concentrations in home dust are attributed to releases from paint during home renovation. This implies that exposure of construction workers to Ti- and La-bearing particles during home renovation may potentially pose human health risks.more » « less
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Detrital zircon (DZ) U‐Pb laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) has revolutionised the way geologists approach many Earth science questions. Although recent research has focused on rapid sample throughput, acquisition rates are limited to 100–300 analyses h−1. We present a method to acquire zircon U‐Pb dates at rates of 120, 300, 600 and 1200 analyses h−1(30, 12, 6 and 3 s per analysis) by multi‐collector LA‐ICP‐MS. We demonstrate the efficacy of this method by analysing twelve zircon reference materials with dates from ~ 3465 to ~ 28 Ma. Mean offset from high‐precision dates increases with faster rates from 0.9% to 1.1%; mean random 1
s uncertainty increases from 0.6% to 1.3%. We tested this new method on a sandstone sample previously characterised by large‐n DZ geochronology. Quantitative comparison shows increased correspondence among age distributions comprising > 300 dates. This new method holds promise for DZ geochronology because (a) it requires no major changes to hardware, but rather modifications to software; (b) it yields robust age distributions well‐suited for quantitative analysis and maximum depositional age calculations; (c) there is only a minor sacrifice of accuracy and measurement uncertainty; and (d) there is less burden to researchers in terms of time investment and analytical cost.
