Phytochemical and antioxidant properties of different solvent extracts of Kirkia wilmsii tubers

Objective:To determine suitable phytochemical extraction solvents,screen for phytochemicals,determine the total phenol and flavonoid contents and the antioxidant activities of different solvent extracts of Kirkia wilmsii(K.wilmsii),an ethnomedicine in South Africa.Methods:Extractions were performed from dried tubers of the K.wilmsii plant,using several solvents and varying extraction times.Extract yields were determined and suitable extraction solvents were selected.Total phenol and flavonoid contents of the extracts were determined spectrophotometrically using gallic acid and quercetin as standards.The free radical scavenging activity of the extracts was investigated using l,l-diphenyl-2-picrylhydrazyl radical.Results:Phytochemical screening confirmed the presence of phenolics,flavonoids,terpenoids,tannins,cardenolide deoxy sugars and reducing sugars.Of the 12 solvent extracts used,six gave yields higher than 5%,while the other six gave yields less than 1%.The highest extract yield of 52.9%was obtained using 80%methanol while the lowest yield of 7.3%was obtained using ethanol at 60 min.The 80%methanol,methanol/chloroform/water(12:5:3)and 60%methanol extracts were significantly higher than those of ethanol,methanol and water(P < 0.05).Total phenolic content recorded extracts ranged from(45.32 ± 0.50) to(122.84 ± 0.31) mg gallic acid equivalent per gram.A maximum total flavonoid content of(917.02 ± 0.10) mg quercetin equivalent per gram and a minimum of(206.26 ± 0.10) mg quercetin equivalent per gram were recorded for methanol and water,respectively.The flavonoid content for methanol was significantly higher than all the other extracts(P < 0.05).The scavenging profiles of K.wilmsii extracts were significantly lower(P < 0.05) than that of ascorbic acid and IC50 values ranged from 129.94 μg/mL for methanol to 225.04 μg/mL for water.An IC50 value of 56.52μg/mL was obtained with ascorbic acid.Conclusions:Ethanol,methanol,methanol/chloroform/water,80%methanol,60%methanol and water can be used as suitable phytochemical extraction solvents for K.wilmsii tubers.Total phenolic content and total flavonoid content analysis proved the presence of high levels of phenolic compounds as well as flavonoids.The presence of phenols and flavonoid could be responsible for the radical scavenging activities observed.

Chemoprotective activity of aqueous leaf extract of Acalypha wilkesiana against cyclophosphamide-induced toxicity in rats

Objective:To investigate the protective effect of aqueous leaf extract of Acalypha(A.)wilkesiana Muell.Arg(Euphorbiaceae)against cyclophosphamide-induced toxicity in albino rats.Methods:Twenty male albino rats were randomly divided into five groups of four animals each.The control group(Ⅰ)was fed with pellets and distilled water,while group Ⅱ was orally administered with only 20 mg/kg cyclophosphamide.Groups Ⅲ,Ⅳ and Ⅴ were coadministered with 20 mg/kg body weight cyclophosphamide and 110,220 and 440 mg/kg body weight A.wilkesiana leaf extract,respectively,for 7 d.After treatment,liver and kidney function biomarkers,haematological parameters,liver antioxidants,and mitochondrial membrane permeability transition pore opening were investigated.Results:A.wilkesiana leaf extract significantly reduced(P<0.05)cyclophosphamide-induced increase in plasma aspartate aminotransferase,alanine aminotransferase,creatinine,uric acid and urea.It increased superoxide dismutase,catalase,glutathione-S-transferase activities and reduced glutathione levels.It also increased packed cell volume count,hemoglobin concentration and white blood cell count while inhibiting the induction of mitochondrial swelling.Conclusions:This study demonstrates that aqueous extract of A.wilkesiana leaf protected tissues against cyclophosphamide-induced oxidative damage.

Internalising solar radiation management technological externalities： An ethical review on the design of economic instruments

1. IntroductionA geoengineering approach for removing atmospheric CO2is growing in the climate science literature and climate policyresearch. The recent Fifth Assessment Report （AR5） of TheIntergovernmental Panel on Climate Change （IPCC, 2014）which provides a clear and up-to-date assessment of the currentstate of scientific knowledge relevant to climate changebrings climate engineering from the fringes of the policydebate into the mainstream. Solar radiation management（SRM） involves large-scale methods that seek to reduce theamount of absorbed solar energy in the climate systems andcould to some degree offset global temperature rise and itseffects.

Analysis of Volutin Granule Formation in <i>Saccharomyces cerevisiae</i>

The budding yeast Saccharomyces cerevisiae serves as an effective model organism for many cellular pathways including phosphate transport, accumulation, and storage. In S. cerevisiae, phosphate is actively transported across the plasma membrane via several phosphate carriers and is then transported into the acidic vacuole (roughly equivalent to the mammalian lysosome with degradative functions but with additional storage functions, such as calcium) where it is synthesized into volutin, a storage form of polyphosphate, found in many organisms. We have been studying volutin granule formation in wild type cells to determine the physiological requirements for formation and in mutants to determine the pathway by which the volutin biosynthetic proteins are transported to the vacuole. Undertaking an analysis of volutin formation in yeast vacuoles by blocking vacuole function with pharmacological agents, such as ionomycin and CCCP, we see that vacuole pH as well as vacuolar calcium seems critical for volutin formation. Different blocks in vacuolar protein sorting have differential effects on volutin granule accumulation, with volutin granule formation seen in all mutant strains thus far tested, except for vps33, a mutant cell strain lacking all vacuolar structure. Our data are consistent with pleiotrophic effects of vacuolar physiological function blocks leading to a decrease in volutin formation.

Luminometric Studies of Yeast Response to Complex Environmental Calcium Variations Demonstrate Sensing of External Calcium Ion Changes

The response of yeast to sharp environmental increases in calcium concentration has been extensively studied. However, systematic studies of the response under more general changes are still lacking. Only limited exploration of cellular responses has been conducted where calcium concentration is decreased. This article describes a set of luminometric experiments that monitor the cytosolic calcium concentration under changing external concentration conditions. As a decrease in external calcium concentrations requires the use of large sample volumes, the experiments require the use of equipment adapted for this purpose. We describe the modification of commercial luminometric equipment to make the exploration possible. We explore the yeast cellular behavior when an increase in external calcium concentration is followed by a decrease in external calcium concentration. We compare these results with those from the case of a double pulse of concentration increase. Results from the experiment show that the first, concentration increasing pulse produces the well-known sharp increase in cytosolic calcium followed by calcium sequestration to return to a cytosolic concentration near its initial condition. Surprisingly, the calcium decrease step shows similar results with a cytosolic increase followed by a return to lower levels. The results suggest the presence of a calcium sensing mechanism regulating calcium influx from external sources. This mechanism would produce channel opening as a response to any changes in external concentration, be it an enhancement or a depletion.

Comparative assessment on rodent impacts and cultural perceptions of ecologically based rodent management in 3 Afro-Malagasy farming regions

Rodents generate negative consequences for smallholder farmers in Africa that directly impact household and livestock damage,food security,and public health.Ecologically Based Rodent Management(EBRM)seeks sustainable solutions for the mitigation of rodent damage through assessments of rodent population dynamics,agro-ecosystems,and socio-cultural contexts.We adopt a comparative approach across 3 rural Afro-Malagasy smallholder farming regions in South Africa,Tanzania,and Madagascar to assess the household impacts of rodent pests and current perceptions and preferences associated with several rodent control measures.We conducted focus group questionnaires and interviews in different study site locations.Rodents assert multiple impacts on Afro-Malagasy farmers demonstrating recurrent and emerging agricultural and household costs,and public health impacts.We identify a significant knowledge gap in educating communities about the application of different EBRM approaches in favor of acute poisons that are perceived to be more effective.Cultural issues and taboos also have a significant impact on the social acceptance of rodent hunting as well as biological control using indigenous predators.We advocate for an enhanced investigation of the socio-cultural beliefs associated with different rodent practices to understand the factors underlying social acceptance.A collaborative approach that integrates the perspectives of target communities to inform the design of EBRM initiatives according to the specific agro-ecosystem and socio-cultural context is necessary to ensure programmatic success.

Individual variation in ballooning dispersal by black widow spiderlings： The effects of family and social rearing

Individual behavioral variation is ubiquitous across taxa and important to understand if we wish to fully use beha- vioral data to understand the ecology and evolution of organisms. Only recently have studies of individual variation in dispersal behavior become a focus of research. A better understanding of individual variation in dispersal behavior is likely to improve our understanding of population dynamics. In particular, the dynamics of critically small populations （endangered species） and large populations （pest species） may be driven by unique dispersal variants. Here we documented individual variation in the ballooning dispersal behavior of Western black widow spiderlings Latrodectus hesperus, an urban pest species found in superabundant in- festations throughout cities of the desert Southwest USA. We found a great deal of family-level variation in ballooning dispersal, and this variation was highly consistent （repeatable） across time. Maternal egg investment was a poor predictor of this ballooning dispersal. Instead, we show that spiderlings reared in isolation are significantly slower to disperse than spiderlings raised in a more natural setting surrounded by full siblings. Thus, our study examines a widespread but poorly understood dispersal behavior （ballooning）, and suggests urban pest population dynamics are likely driven by the interaction of variation in individuals, families and social environments

Genetic differentiation between and within Northern Native American language groups:an argument for the expansion of the Native American CODIS database

The National Research Council recommends that genetic differentiation among subgroups of ethnic samples be lower than 3%of the total genetic differentiation within the ethnic sample to be used for estimating reliable random match probabilities for forensic use.Native American samples in the United States’Combined DNA Index System(CODIS)database represent four language families:Algonquian,Na-Dene,Eskimo-Aleut,and Salishan.However,a minimum of 27 Native American language families exists in the US,not including language isolates.Our goal was to ascertain whether genetic differences are correlated with language groupings and,if so,whether additional language families would provide a more accurate representation of current genetic diversity among tribal populations.The 21 short tandem repeat(STR)loci included in the Globalfiler^(■)PCR Amplification Kit were used to characterize six indigenous language families,including three of the four represented in the CODIS database(i.e.Algonquian,Na-Dene,and Eskimo-Aleut),and two language isolates(Miwok and Seri)using major population genetic diversity metrics such as F statistics and Bayesian clustering analysis of genotype frequencies.Most of the genetic variation(97%)was found to be within language families instead of among them(3%).In contrast,when only the three of the four language families represented in both the CODIS database and the present study were considered,4%of the genetic variation occurred among the language groups.Bayesian clustering resulted in a maximum posterior probability indicating three genetically distinct groups among the eight language families and isolates:(1)Eskimo,(2)Seri,and(3)all other language groups and isolates,thus confirming genetic subdivision among subgroups of the CODIS Native American database.This genetic structure indicates the need for an increased number of Native American populations based on language affiliation in the CODIS database as well as more robust sample sets for those language families.

Detecting Fake News Over Online Social Media via Domain Reputations and Content Understanding

Fake news has recently leveraged the power and scale of online social media to effectively spread misinformation which not only erodes the trust of people on traditional presses and journalisms, but also manipulates the opinions and sentiments of the public. Detecting fake news is a daunting challenge due to subtle difference between real and fake news. As a first step of fighting with fake news, this paper characterizes hundreds of popular fake and real news measured by shares, reactions, and comments on Facebook from two perspectives:domain reputations and content understanding. Our domain reputation analysis reveals that the Web sites of the fake and real news publishers exhibit diverse registration behaviors, registration timing, domain rankings, and domain popularity. In addition, fake news tends to disappear from the Web after a certain amount of time. The content characterizations on the fake and real news corpus suggest that simply applying term frequency-inverse document frequency(tf-idf) and Latent Dirichlet Allocation(LDA) topic modeling is inefficient in detecting fake news,while exploring document similarity with the term and word vectors is a very promising direction for predicting fake and real news. To the best of our knowledge, this is the first effort to systematically study domain reputations and content characteristics of fake and real news, which will provide key insights for effectively detecting fake news on social media.

Quantifying compliance with COVID-19 mitigation policies in the US: A mathematical modeling study

The outbreak of COVID-19 disrupts the life of many people in the world.In response to this global pandemic,various institutions across the globe had soon issued their prevention guidelines.Governments in the US had also implemented social distancing policies.However,those policies,which were designed to slow the spread of COVID-19,and its compliance,have varied across the states,which led to spatial and temporal heterogeneity in COVID-19 spread.This paper aims to propose a spatio-temporal model for quantifying compliance with the US COVID-19 mitigation policies at a regional level.To achieve this goal,a specific partial differential equation(PDE)is developed and validated with shortterm predictions.The proposed model describes the combined effects of transboundary spread among state clusters in the US and human mobilities on the transmission of COVID-19.The model can help inform policymakers as they decide how to react to future outbreaks.