•We use sap flux to determine stand water use (S) for 3 mangrove forests in Florida.•We compare rates of S with evapotranspiration (ET).•S represented 34–66% of ET, depending on forest structural ...characteristics.•S ranged from conservative rates of 350mmyear−1 to higher rates of 872mmyear−1.•Many mangrove forests are small in stature and likely conservative in water use.
Leaves from mangrove forests are often considered efficient in the use of water during photosynthesis, but less is known about whole-tree and stand-level water use strategies. Are mangrove forests as conservative in water use as experimental studies on seedlings imply? Here, we apply a simple model to estimate stand water use (S), determine the contribution of S to evapotranspiration (ET), and approximate the distribution of S versus ET over annual cycles for three mangrove forests in southwest Florida, USA. The value of S ranged from 350 to 511mmyear−1 for two mangrove forests in Rookery Bay to 872mmyear−1 for a mangrove forest along the Shark River in Everglades National Park. This represents 34–49% of ET for Rookery Bay mangroves, a rather conservative rate of S, and 63–66% of ET for the Shark River mangroves, a less conservative rate of S. However, variability in estimates of S in mangroves is high enough to require additional study on the spatial changes related to forest structural shifts, different tidal regimes, and variable site-specific salinity concentrations in multiple mangrove forests before a true account of water use conservation strategies can be understood at the landscape scale. Evidence does suggest that large, well-developed mangrove forests have the potential to contribute considerably to the ET balance; however, regionally most mangrove forests are much smaller in stature in Florida and likely contribute less to regional water losses through stand-level transpiration.
The aim of this study was to determine the presence of SARS-CoV-2 on food surfaces and surfaces in public spaces in 3 districts of Lima, Peru. A cross-sectional descriptive study was carried out in ...three districts of the Lima metropolitan area. Surfaces that were most exposed to users were selected. Samples were swabbed for 4 weeks and transported to the laboratory to determine the presence of the virus. One thousand ninety-five inert surface samples and 960 food surface samples were evaluated for the identification of SARS-CoV-2 by the real time-PCR molecular test, whereby only one sample from an automated teller machine was positive. Most of the inert and food surfaces evaluated did not show the presence of SARS-CoV-2 during the time of sample collection. Despite the negative results, the frequency of disinfection and hygiene measures on highcontact surfaces should be maintained and increased to prevent other highly contagious infectious diseases. Key words: Inert surfaces; Food; SARS-CoV-2
To determine the value of contrast-enhanced computed tomography (CT)-derived radiomic features in the preoperative prediction of Ki-67 expression in adrenocortical carcinoma (ACC) and to detect ...significant associations between radiomic features and Ki-67 expression in ACC.
For this retrospective analysis, patients with histopathologically proven ACC were reviewed. Radiomic features were extracted for all patients from the preoperative contrast-enhanced abdominal CT images. Statistical analysis identified the radiomic features predicting the Ki-67 index in ACC and analysed the correlation with the Ki-67 index.
Fifty-three cases of ACC that met eligibility criteria were identified and analysed. Of the radiomic features analysed, 10 showed statistically significant differences between the high and low Ki-67 expression subgroups. Multivariate linear regression analysis yielded a predictive model showing a significant association between radiomic signature and Ki-67 expression status in ACC (R2=0.67, adjusted R2=0.462, p=0.002). Further analysis of the independent predictors showed statistically significant correlation between Ki-67 expression and shape flatness, elongation, and grey-level long run emphasis (p=0.002, 0.01, and 0.04, respectively). The area under the curve for identification of high Ki-67 expression status was 0.78 for shape flatness and 0.7 for shape elongation.
Radiomic features derived from preoperative contrast-enhanced CT images show encouraging results in the prediction of the Ki-67 index in patients with ACC. Morphological features, such as shape flatness and elongation, were superior to other radiomic features in the detection of high Ki-67 expression.
•The Ki-67 index is considered one of the most important established prognostic markers for local recurrence of adrenocortical carcinoma.•Preoperative CT studies can be utilized to predict the Ki-67 index in patients with adrenocortical carcinoma.•Morphological features such as shape flatness and elongation are associated with a high Ki-67 index.
The volatile gas isoprene is emitted in teragrams per annum quantities from the terrestrial biosphere and exerts a large effect on atmospheric chemistry. Isoprene is made primarily from recently ...fixed photosynthate; however, alternate carbon sources play an important rolé, particularly when photosynthate is limiting. We examined the relative contribution of these alternate carbon sources under changes in light and temperature, the two environmental conditions that have the strongest influence over isoprene emission. Using a novel real-time analytical approach that allowed us to examine dynamic changes in carbon sources, we observed that relative contributions do not change as a function of light intensity. We found that the classical uncoupling of isoprene emission from net photosynthesis at elevated leaf temperatures is associated with an increased contribution of alternate carbon. We also observed a rapid compensatory response where alternate carbon sources compensated for transient decreases in recently fixed carbon during thermal ramping, thereby maintaining overall increases in isoprene production rates at high temperatures. Photorespiration is known to contribute to the decline in net photosynthesis at high leaf temperatures. A reduction in the temperature at which the contribution of alternate carbon sources increased was observed under photorespiratory conditions, while photosynthetic conditions increased this temperature. Feeding 2-¹³C glycine (a photorespiratory intermediate) stimulated emissions of ¹³C₁-₅ isoprene and ¹³CO₂, supporting the possibility that photorespiration can provide an alternate source of carbon for isoprene synthesis. Our observations have important implications for establishing improved mechanistic predictions of isoprene emissions and primary carbon metabolism, particularly under the predicted increases in future global temperatures.
Stress granules (SGs) are sites for mRNA storage, protection, and translation repression. TIA1 and TIAR1 are two RNA-binding proteins that are key players in SGs formation in mammals. TIA1/TIAR have ...a prion-like domain (PrD) in their C-terminal that promotes liquid-phase separation. Lack of any TIA1/TIAR has severe consequences in mice. However, it is not clear whether the failure to form proper SGs is the cause of any of these problems. We disrupted two predicted α-helices within the prion-like domain of the
TIA1/TIAR homolog, TIAR-1, to test whether its association with SGs is important for the nematode. We found that
PrD mutant animals continued to form TIAR-1 condensates under stress in the
gonad. Nonetheless, TIAR-1 condensates appeared fragile and disassembled quickly after stress. Apparently, the SGs continued to associate regularly as observed with CGH-1, an SG marker. Like
-knockout nematodes,
PrD mutant animals exhibited fertility problems and a shorter lifespan. Notwithstanding this,
PrD mutant nematodes were no sensitive to stress. Our data demonstrate that the predicted prion-like domain of TIAR-1 is important for its association with stress granules. Moreover, this domain may also play a significant role in various TIAR-1 functions unrelated to stress, such as fertility, embryogenesis and lifespan.
From April 2014 to January 2015, ozone (O3) dynamics were investigated as part of GoAmazon 2014/5 project in the central Amazon rainforest of Brazil. Just above the forest canopy, maximum hourly O3 ...mixing ratios averaged 20 ppbv (parts per billion on a volume basis) during the June–September dry months and 15 ppbv during the wet months. Ozone levels occasionally exceeded 75 ppbv in response to influences from biomass burning and regional air pollution. Individual convective storms transported O3-rich air parcels from the mid-troposphere to the surface and abruptly enhanced the regional atmospheric boundary layer by as much as 25 ppbv. In contrast to the individual storms, days with multiple convective systems produced successive, cumulative ground-level O3 increases. The magnitude of O3 enhancements depended on the vertical distribution of O3 within storm downdrafts and origin of downdrafts in the troposphere. Ozone mixing ratios remained enhanced for > 2 h following the passage of storms, which enhanced chemical processing of rainforest-emitted isoprene and monoterpenes. Reactions of isoprene and monoterpenes with O3 are modeled to generate maximum hydroxyl radical formation rates of 6×106 radicals cm−3s−1. Therefore, one key conclusion of the present study is that downdrafts of convective storms are estimated to transport enough O3 to the surface to initiate a series of reactions that reduce the lifetimes of rainforest-emitted hydrocarbons.
•In the rainforest, convective storms transport ozone-rich air to the surface.•Ozone levels remain enhanced for more than 2 h after the passage of storms.•Enhanced ozone drives oxidation of rainforest-emitted hydrocarbons.
Inland sources of particulate chloride for atmospheric nitryl chloride (ClNO2) formation remain unknown and unquantified, hindering air quality assessments. Globally each winter, tens of millions of ...tons of road salt are spread on roadways for deicing. Here, we identify road salt aerosol as the primary chloride aerosol source, accounting for 80–100% of ClNO2 formation, at an inland urban area in the wintertime. This study provides experimental evidence of the connection between road salt and air quality through the production of this important reservoir for nitrogen oxides and chlorine radicals, which significantly impact atmospheric composition and pollutant fates. A numerical model was employed to quantify the contributions of chloride sources to ClNO2 production. The traditional method for simulating ClNO2 considers chloride to be homogeneously distributed across the atmospheric particle population; yet, we show that only a fraction of the particulate surface area contains chloride. Our new single-particle parametrization considers this heterogeneity, dramatically lowering overestimations of ClNO2 levels that have been routinely reported using the prevailing methods. The identification of road salt as a ClNO2 source links this common deicing practice to atmospheric composition and air quality in the urban wintertime environment.
Air pollution modifies floral scent trails McFrederick, Quinn S.; Kathilankal, James C.; Fuentes, Jose D.
Atmospheric environment (1994),
03/2008, Letnik:
42, Številka:
10
Journal Article
Recenzirano
Floral hydrocarbons provide essential signals to attract pollinators. As soon as they are emitted to the atmosphere, however, hydrocarbons are destroyed by chemical reactions involving pollutants ...such as ozone. It is therefore likely that increased air pollution interferes with pollinator attracting hydrocarbon signals. To test this hypothesis, a Lagrangian diffusion model was used to determine the position of air parcels away from hydrocarbon sources and to estimate the rate of chemical destruction of hydrocarbons as air parcels moved across the landscape. The hydrocarbon compounds linalool,
β-myrcene, and
β-ocimene were chosen because they are known to be common scents released from flowers. The suppressed ambient abundances of volatile organic compounds were determined in response to increased regional levels of ozone, hydroxyl, and nitrate radicals. The results indicate that the documented increases in air pollution concentrations, from pre-industrial to present times, can lead to reductions in volatile compound concentrations insects detect as they pollinate flowers. For highly reactive volatiles the maximum downwind distance from the source at which pollinators can detect the scents may have changed from kilometers during pre-industrial times to <200
m during the more polluted conditions of present times. The increased destruction of floral signals in polluted air masses may have important implications for both pollinators and signaling plants. When patches of flowers are further apart than the visual range of pollinators, such as in fragmented landscapes, the loss of scent signals may mean that pollinators spend more time searching for patches and less time foraging. This decrease in pollinator foraging efficiency will simultaneously decrease the pollinator's reproductive output and the amount of pollen flow in flowering plants.
PDF
