192 research outputs found
Evaluation of traditionally used medicinal plants for anticancer, antioxidant, anti-inflammatory and anti-viral (HPV-1) activity
The aim of this study was to determine the anticancer, antioxidant, anti-inflammatory and antiviral activities of traditionally used medicinal plants.The extracts were tested for cytotoxicity against human melanoma (A375), epidermoid carcinoma (A431), cervical epithelial carcinoma (HeLa) and human embryonic kidney cells (HEK-293). The antioxidant and anti-inflammatory activities were also determined. Gomphocarpus fruticosus, Helichrysum kraussii and Syzygium jambos were selected for activity against the herpes simplex virus type-1.The extracts exhibited low toxicity towards HEK-293 cells, and four extracts; namely Acacia mellifera, G. fruticosus, H. kraussii and S. jambos, were able to inhibit the A431 and HeLa cells with 50% inhibitory concentrations (IC50) ranging from 34.90-56.20μg/ml. Arbutus unedo, Combretum molle, Dissotis princeps, Erythrophleum lasianthum, Harpephyllum caffrum, H. kraussii and S. jambos, showed high DPPH inhibitory activity, with IC50 values ranging from 2.41-5.25μg/ml. The highest antioxidant activity was seen for S. jambos (DPPH) and A. unedo (NO) respectively with greater activity than ascorbic acid. D. princeps, H. caffrum, Leucas martinicensis and S. jambos, showed high inhibition of the cyclooxygenase-2 (COX-2) enzyme with IC50 values ranging from 3.79-25.80μg/ml with S. jambos showing the highest activity. S. jambos further showed the highest anti-HSV-1 activity at 50.00μg/ml against 100TCID50virus challenge dose.This is the first report of the selected plants for their cytotoxicity, anti-inflammatory and viral inhibitory activity. S. jambos was able to show high inhibition of the HPV type-1 virus and the COX-2 enzyme.The National Research Foundation of South Africa (84870), the University of Pretoria and the Department of Science and Technology. Walter Sisulu National Botanical Gardens (SANBI).http://www.elsevier.com/locate/sajb2018-09-30hj2017Plant Production and Soil Scienc
Improving the transferability of suspended solid estimation in wetland and deltaic waters with an empirical hyperspectral approach
The deposition of suspended sediment is an important process that helps wetlands accrete surface material and maintain elevation in the face of sea level rise. Optical remote sensing is often employed to map total suspended solids (TSS), though algorithms typically have limited transferability in space and time due to variability in water constituent compositions, mixtures, and inherent optical properties. This study used in situ spectral reflectances and their first derivatives to compare empirical algorithms for estimating TSS using hyperspectral and multispectral data. These algorithms were applied to imagery collected by NASA’s Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) over coastal Louisiana, USA, and validated with a multiyear in situ dataset. The best performing models were then applied to independent spectroscopic data collected in the Peace–Athabasca Delta, Canada, and the San Francisco Bay–Delta Estuary, USA, to assess their robustness and transferability. A derivative-based partial least squares regression (PLSR) model applied to simulated AVIRIS-NG data showed the most accurate TSS retrievals (R2 = 0.83) in these contrasting deltaic environments. These results highlight the potential for a more broadly applicable generalized algorithm employing imaging spectroscopy for estimating suspended solids
Assessment of ecosystem services of an urbanized tropical estuary with a focus on habitats and scenarios
Tropical estuaries are one of the most valuable ecosystems on the planet because of the number of ecosystem services they provide. The increasing anthropogenic pressure to which these estuaries are subject has caused a reduction in their natural capital stock. Therefore, the application of a pragmatic and rational ecosystem-based management approach to sustainably manage the multiple ecosystem services provided by this ecosystem is necessary. The aim of our study is to present an approach that combines prospective scenarios with habitat-based perspective to assess the supply capacity of ecosystem services, plus determine the impact of protected areas in an urbanized tropical estuary. The current situation and two scenarios were generated to evaluate the capacity of habitats to supply ecosystem services. This type of assessment will allow the decision makers to visualize the effect of their choices or the occurrence of events which might produce significant changes in the estuary. Thus, over time, measures can be taken to sustain the supply of ecosystem services. We determined that the establishment of protected areas have a positive impact; however, the effect is not the same for all of them. Consequently, indicating that actions such as community participation, research, education, management planning and infrastructure development must accompany the development of a protected area
The Impact of Accelerating Land-Use Change on the N-Cycle of Tropical Aquatic Ecosystems: Current Conditions and Projected Changes
Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone
Applying cumulative effects to strategically advance large-scale ecosystem restoration
International efforts to restore degraded ecosystems will continue to expand over the coming decades, yet the factors contributing to the effectiveness of long-term restoration across large areas remain largely unexplored. At large scales, outcomes are more complex and synergistic than the additive impacts of individual restoration projects. Here, we propose a cumulative-effects conceptual framework to inform restoration design and implementation and to comprehensively measure ecological outcomes. To evaluate and illustrate this approach, we reviewed long-term restoration in several large coastal and riverine areas across the US: the greater Florida Everglades; Gulf of Mexico coast; lower Columbia River and estuary; Puget Sound; San Francisco Bay and Sacramento–San Joaquin Delta; Missouri River; and northeastern coastal states. Evidence supported eight modes of cumulative effects of interacting restoration projects, which improved outcomes for species and ecosystems at landscape and regional scales. We conclude that cumulative effects, usually measured for ecosystem degradation, are also measurable for ecosystem restoration. The consideration of evidence-based cumulative effects will help managers of large-scale restoration capitalize on positive feedback and reduce countervailing effects
Integrated Carbon Budget Models for the Everglades Terrestrial-Coastal-Oceanic Gradient: Current Status and Needs for Inter-Site Comparisons
Recent studies suggest that coastal ecosystems can bury significantly more C than tropical forests, indicating that continued coastal development and exposure to sea level rise and storms will have global biogeochemical consequences. The Florida Coastal Everglades Long Term Ecological Research (FCE LTER) site provides an excellent subtropical system for examining carbon (C) balance because of its exposure to historical changes in freshwater distribution and sea level rise and its history of significant long-term carbon-cycling studies. FCE LTER scientists used net ecosystem C balance and net ecosystem exchange data to estimate C budgets for riverine mangrove, freshwater marsh, and seagrass meadows, providing insights into the magnitude of C accumulation and lateral aquatic C transport. Rates of net C production in the riverine mangrove forest exceeded those reported for many tropical systems, including terrestrial forests, but there are considerable uncertainties around those estimates due to the high potential for gain and loss of C through aquatic fluxes. C production was approximately balanced between gain and loss in Everglades marshes; however, the contribution of periphyton increases uncertainty in these estimates. Moreover, while the approaches used for these initial estimates were informative, a resolved approach for addressing areas of uncertainty is critically needed for coastal wetland ecosystems. Once resolved, these C balance estimates, in conjunction with an understanding of drivers and key ecosystem feedbacks, can inform cross-system studies of ecosystem response to long-term changes in climate, hydrologic management, and other land use along coastlines
Priming Analogical Reasoning with False Memories
Like true memories, false memories are capable of priming answers to insight-based problems. Recent research has attempted to extend this paradigm to more advanced problem-solving tasks, including those involving verbal analogical reasoning. However, these experiments are constrained inasmuch as problem solutions could be generated via spreading activation mechanisms (much like false memories themselves) rather than using complex reasoning processes. In three experiments we examined false memory priming of complex analogical reasoning tasks in the absence of simple semantic associations. In Experiment 1, we demonstrated the robustness of false memory priming in analogical reasoning when backward associative strength among the problem terms was eliminated. In Experiments 2a and 2b, we extended these findings by demonstrating priming on newly created homonym analogies that can only be solved by inhibiting semantic associations within the analogy. Overall, the findings of the present experiments provide evidence that the efficacy of false memory priming extends to complex analogical reasoning problems
Global dataset of soil organic carbon in tidal marshes.
Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha-1 in the top 30 cm and 231 ± 134 Mg SOC ha-1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies
Absence of domestic triatomine colonies in an area of the coastal region of Ecuador where Chagas disease is endemic
- …