Hasil untuk "Natural history (General)"

Samuel Finnikin, James O’Hara, Tom Marshall

Abstract Background Recurrent sore throat affects a small minority of adults but can cause substantial morbidity. Evidence to guide tonsillectomy eligibility in adults is limited, and current criteria are extrapolated from paediatric populations. We aimed to describe the epidemiology, management, and prognosis of adult sore throat in UK primary care. Methods Using CPRD Aurum (2010–2020 adults with a first coded episode of sore throat or tonsillitis were identified and matched to controls. Episode frequency, antibiotic use, ENT referral, and tonsillectomy were analysed. Predictors of recurrent episodes (≥3 in 365 days), referral, and tonsillectomy were assessed using time-to-event, multinomial logistic, and multilevel mixed-effects regression models. Findings Of 4.45 million adults, 1.70 million (38.3%) had ≥1 episode; most (61.5%) had only one, but 4.1% experienced ≥3 within 1 year. Recurrent episodes were more common in younger females and those from more deprived areas. Only 21,869 patients (0.5% of the exposed cohort) underwent tonsillectomy, and just 25.7% of these met Paradise criteria at any time; conversely, only 13.9% of those meeting criteria underwent surgery. Patients who had a tonsillectomy tended to be younger, female, and from less deprived areas. Pre-tonsillectomy episode rates were unexpectedly low, but the data indicated that individuals with high baseline burden continue to experience elevated episode rates over several years. Conclusions Recurrent sore throat is uncommon, but those affected face substantial disease burden. Current tonsillectomy patterns are poorly aligned with disease burden and show inequities by deprivation. Earlier identification of adults likely to develop recurrent episodes, and more timely surgical intervention, may improve patient outcomes and the cost-effectiveness of tonsillectomy.

Ivet A. Yordanova, Joseph B. Prescott

Abstract Marburg virus (MARV) is a highly pathogenic zoonotic filovirus. The Orthomarburgvirus marburgense species includes MARV and Ravn virus (RAVV), which differs from MARV by 21% at the nucleotide level and 22% at the protein level. This review offers fresh discussions of the epidemiology, genetics and natural reservoir transmission of RAVV, summarizes experimental animal models, outlines current vaccine development and raises outstanding questions about RAVV life history, transmission and pathogenicity.

Qiuhua Yang, Lili Wang, Yanfang Zhong et al.

In autumn 2020, cultured sea cucumbers (Apostichopus japonicus) in the Xiapu Sea area (Southeast China) exhibited ulcerative skin lesions. To identify the causative pathogen, the Gram-negative strain 10MKXP20 was isolated from the muscle tissue of diseased animals and identified as Photobacterium leiognathi through phenotypic and genetic analysis. The bacterium was sensitive to 14 antibiotics, including tetracycline and enrofloxacin, but resistant to gentamicin, neomycin, kanamycin, rifampicin, amikacin, and amoxicillin. Minimum inhibitory concentration (MIC) assays revealed varying efficacy among the tested antibiotics, with enrofloxacin, doxycycline, and florfenicol showing particularly low MICs, indicating strong inhibitory activity. Challenge experiments via immersion and intramuscular injection confirmed the pathogenicity of P. leiognathi 10MKXP20, with mortality rates being dose-dependent. This study is the first to identify P. leiognathi as the causative agent of ulcerative skin disease in sea cucumbers, providing crucial insights for disease diagnosis and antibiotic treatment.

Stefanie Simpson, Lindsey S. Smart, Lindsey S. Smart et al.

Blue carbon ecosystems, such as mangroves, tidal marshes, and seagrasses, are important for climate mitigation. As carbon sinks, they often exhibit higher per hectare carbon storage capacity and sequestration rates than terrestrial systems. These ecosystems provide additional benefits, including enhancing water quality, sustaining biodiversity, and maintaining coastal resilience to climate change impacts. The widespread loss of blue carbon ecosystems due to anthropogenic activities can contribute to increasing carbon emissions globally. Monetizing blue carbon through carbon credits offers an avenue to generate revenue and incentivize conservation and restoration efforts. However, limited data on project costs and carbon benefits make prioritization of blue carbon projects challenging. To address these challenges, we have developed, in collaboration with blue carbon experts, the Blue Carbon Cost Tool. This is a user-friendly interface enabling comparison of three core market project components – 1) carbon credit estimation, 2) project cost estimation, and 3) a qualitative, non-economic feasibility assessment – to assess and compare potential for blue carbon projects. Tool simulations with data available from nine countries demonstrate (a) how factors such as country, ecosystem type and project scale drive variability, (b) the need for local or project-specific data to enhance accuracy and reduce uncertainty, particularly in tidal marsh and seagrass systems, and (c) that higher price tolerance or upfront capital is needed to bridge implementation and maintenance cost gaps. The Blue Carbon Cost Tool can aid project developers and investors to better understand market opportunity and the resources needed to develop high quality blue carbon market projects.

Chenyang Huang, Jing Li, Min Zhang et al.

Abstract. Hepatitis B virus (HBV) infection is a global epidemic whose prevention and control among children warrant significant attention. Despite the availability of effective vaccines, the disease continues to affect millions of children worldwide, underscoring the need for a comprehensive understanding of its epidemiology and natural history in this vulnerable population. While research on HBV in adults has advanced considerably, the natural history of HBV infection in children remains less well-defined and may differ from adult studies due to unique immunological and physiological characteristics. This article reviews the epidemiological characteristics of HBV infection in children worldwide and summarizes the research progress on the natural outcomes of children with chronic HBV infection. Furthermore, the necessity of this review stems from the critical role that early detection, monitoring, and timely intervention play in mitigating the long-term consequences of chronic hepatitis B (CHB) in children. By synthesizing current evidence and identifying knowledge gaps, we hope to inform clinical practice, guide future research directions, and ultimately improve the health outcomes of children living with HBV. In doing so, this review article offers a valuable reference for healthcare providers, researchers, and policymakers working to combat the global challenge of HBV infection among children. The aim is to provide a relevant reference for the monitoring, screening, diagnosis, and treatment of children with CHB.

Jacqueline Leon, Tyler Ohler, Joseph Beckman et al.

Background:  Kratom, derived from a tree species native to Southeast Asia and used in traditional medicine, is gaining popularity within the United States. While at low doses it is intended for stimulant use, higher doses of kratom can achieve analgesic effects similar to opiates. It’s use and misuse continues to be an area of interest given its unregulated status and propensity for addiction and abuse. Here we present four cases of kratom abuse observed in the inpatient and outpatient settings in southcentral Kentucky.   The Case: First, 20-year-old female with medical history of anxiety and major depressive disorder presented to the emergency department due to symptoms of restlessness, body aches, chills, nausea, palpitations and loose stools. Patient revealed she has been taking 7-8 kratom tablets daily and had attempted immediate cessation but relapsed due to her symptoms. In clinic follow up, she was started on Atarax and methyl salicylate patches for symptom control and is currently in process of tapering off Kratom. Next, 49-year-old male with history of hypertension, chronic kidney disease, hyperlipidemia, and chronic pain presented to clinic with recurrent hypertensive episodes. He disclosed chronic use of kratom following MVC 5 years prior, currently taking 10 g every 4-5 hours. With a desire to cut back, the patient and his physician through shared-decision making created a tapering plan. With a slow taper, he has not reported any withdrawal symptoms. As his kratom use trends down, he will be referred to  pain management specialist for chronic pain.  Additionally, 18-year-old male with no significant medical history was brought to the ED being found unresponsive and foaming at the mouth. He was tachypneic, tachycardic, and hypotensive with a mildly elevated troponin. After receiving Narcan and IV fluids, the patient became responsive. Patient disclosed he was taking two 50 mg packages of kratom alongside marijuana and alcohol for recreation. After returning to baseline, the patient was discharged with close outpatient follow up. Lastly, 38-year-old female with medical history of anxiety/depression, seizures, and thyroidectomy complicated by vocal cord dysfunction presented to the ED after being found minimally responsive by family. Family explained the patient took up to 60 kratom tablets daily and she was found to have urine mitragynine level > 2500. Patient initially displayed nonsensical speech, paranoia, and hallucinations, but progressed to hypersomnolence with subsequent seizure and catatonia necessitating ICU admission. Ultimately transferred to tertiary center for benzodiazepine challenge and possible ECT.   Conclusion: Presently, the United States does not regulate the manufacturing or distribution of kratom. In fact, very little is known about the long-term effects safety profile. Due to the demonstrated potential for abuse and harm, six states have made the drug illegal. From our patient interactions, the common theme is one of surreptitious addiction, monetary strain, and little understanding of the risks inherent to what was marketed as a natural supplement.  Further research is warranted appropriately counsel our patients to the potential dangers recreational kratom use poses and improve the understanding  the medical and socioeconomic impact of its wide availability.

Octavio Aburto-Oropeza, Valentina Platzgummer, Erica M. Ferrer et al.

Mechanisms for marine ecological protection and recovery, including area-based conservation tools like ‘Marine Protected Areas’ (MPAs) are necessary tools to reach the Aichi Target or the forthcoming 30x30 target set by the Kunming-Montreal Biodiversity Framework. However, full ecosystem recovery takes years to manifest and the idea that MPA protection alone will foster human well-being is frequently contradicted by socio-economic evidence. Therefore, a new framework for marine area-based conservation and ecosystem restoration that reconciles the discrepancies between ecological recovery and socio-economic growth timelines is needed to effectively meet global biodiversity conservation targets. We introduce the concept of ‘Marine Prosperity Areas,’ (MPpA) an area-based conservation tool that prioritizes human prosperity as opposed to passively relying on ecosystem recovery to catalyze social change and economic growth. This concept leverages a suite of tried-and-true community-based intervention and investment strategies to strengthen and expand access to environmental science, social goods and services, and the financial perks of the blue economy. This data-driven framework may be of interest to stakeholders who support traditional area-based conservation models, but also to those who have been historically opposed to MPAs or have been excluded from past conservation processes.

Mónica-Yanira Rodríguez-Pérez, Laura Sánchez-Velasco, Martha-Patricia Rosas-Hernández et al.

Xueqi Li, Xueqi Li, Qinfeng Gao et al.

A two-stage diet-switch experiment was conducted to examine the hypothesis that the changes in digestive enzyme activities of sea cucumber (Apostichopus japonicus) induced by historic diets might persist in the regenerated intestines. In stage I, A. japonicus were treated with two different diets for 56 days, including diet A with 11% crude protein, 1% crude lipid, and 40% carbohydrate, and diet B with 18% crude protein, 2% crude lipid, and 35% carbohydrate. In stage II, each treatment was subjected to evisceration with 0.35M KCl or not (eviscerated and non-eviscerated groups), half of which were then switched to different diets from diet A to B or vice versa for 112 days. The persistence of digestive enzyme activities was evaluated by measuring the changes in digestive enzyme activities before and after evisceration. In stage I, diets B and A increased trypsin and amylase activities, respectively. In stage II, the higher trypsin activities were observed in eviscerated and non-eviscerated A. japonicus that had consumed diet B in stage I. The higher amylase activities were observed only in eviscerated A. japonicus that had consumed diet A in stage I. It indicated that the historic diets showed long-term effects on the digestion of A. japonicus, which led to the persistence of changes in both trypsin and amylase activities in intestines, especially in the regenerated intestines. In addition, the specific growth rates (SGRs) and metabolic rates (MRs) of A. japonicus were affected by the long-term effects of historic diets. Meanwhile, the relationships between enzymic activities, SGRs, and MRs were observed in A. japonicus, indicating that the historic diets could produce long-term effects on the growth and metabolism of A. japonicus through their long-term effects of historic diets on digestive enzyme activities. In conclusion, the present study showed that the changes in digestive enzyme activities induced by different diets in stage I could persist in the intestines and regenerated intestines, leading to long-term effects of historic diets on the growth and metabolism of A. japonicus.

Amália Maria Sacilotto Detoni, Ajit Subramaniam, Sheean T. Haley et al.

Inputs of new nitrogen by cyanobacterial diazotrophs are critical to ocean ecosystem structure and function. Relative to other ocean regions, there is a lack of data on the distribution of these microbes in the western South Atlantic. Here, the abundance of six diazotroph phylotypes: Trichodesmium, Crocosphaera, UCYN-A, Richelia associated with Rhizosolenia (Het-1) or Hemiaulus (Het-2), and Calothrix associated with Chaetoceros (Het-3) was measured by quantitative PCR (qPCR) of the nifH gene along a transect extending from the shelf-break to the open ocean along the Vitória-Trindade seamount chain (1200 km). Using nifH gene copies as a proxy for phylotype abundance, Crocosphaera signals were the most abundant, with a broad distribution throughout the study region. Trichodesmium signals were the second most abundant, with the greatest numbers confined to the warmer waters closer to the coast, and a significant positive correlation with temperature. The average signals for the host-associated diazotrophs (UCYN-A, Het-1, and Het-2) were consistently lower than for the other phylotypes. These findings expand measurements of cyanobacterial diazotroph distribution in the western South Atlantic, and provide a new resource to enhance modeling studies focused on patterns of nitrogen fixation in the global ocean.

Alison Donnelly, Rong Yu, Katherine Jones et al.

Abstract In recent decades, the use of satellite sensors, near‐surface cameras, and other remote methods for monitoring vegetation phenology at landscape and higher scales has become increasingly common. These technologies provide a means to determine the timing of phenophases and growing season length at different spatial resolutions; coverage that is not attainable by human observers. However, in situ ground observations are required to validate remotely derived phenometrics. Despite increased knowledge and expertise there still remains the persistent challenge of reconciling ground observations at the individual plant level with remotely sensed (RS) phenometrics at landscape or larger scales. We compared the timing of in situ phenophase estimates (spring and autumn) with a range of corresponding remote sensing (moderate resolution imaging spectroradiometer [MODIS], visible infrared imaging radiometer suite [VIIRS], PhenoCam) phenometrics across five terrestrial sites in the United States' NEON (Harvard Forest [MA] [HARV], Onaqui [UT] [ONAQ], Abby Road [WA] [ABBY], Disney Wilderness Preserve [FL] [DSNY], and Ordway‐Swisher Biological Station [FL] [OSBS]) focusing on the 3‐year period from 2017 to 2019. Our main objective was to explore potential reasons for the observed discrepancies between in situ and RS phenometrics and to determine which technologies were better able to capture ground observations. Statistically significant relationships were strongest (p < 0.001) for spring phenophases, while the only RS phenometrics significantly correlated with in situ estimates of autumn phenophases were leaf fall (p < 0.01) and leaves (p < 0.000). In particular, root mean square error (RMSE) (mean bias error [MBE]) for MODIS‐Enhanced Vegetation Index‐2 band (EVI2), VIIRS‐EVI2, and PhenoCam‐green chromatic coordinate (GCC) derived early spring transition dates indicated overall differences of 21.7 days (−4.6 days), 28.4 days (−1.2 days), and 24.1 days (11.9 days) from in situ estimates of early leaf‐out dates. In autumn, RMSE/MBE was smallest (10.9 days/−2.2 days) between phenesse estimates (95th percentile date) of the latest date of in situ leaf fall and VIIRS derived end of senescence, compared to the equivalent phenometric derived from MODIS (13.5 days/7.7 days) and PhenoCam (GCC greenness‐falling) (13.8 days/−5.1 days). Overall, discrepancies between in situ and RS phenology related to scale, species availability, and the short duration of the time series (3 years). However, as the NEON project progresses these challenges are expected to be reduced as more data become available.

Wenhong Pang, Xiaoyan Zhou, Zhijun Dai et al.

Beach intra-tidal bed level changes are of significance to coastal protection amid global climate changes. However, due to the limitation of instruments and the disturbance induced by wave motions superimposed on water levels, it was difficult to detect the high-frequency oscillation of the submerged beach bed level. In this study, an observation, lasting for 12 days and covering the middle tide to the following spring tide, was conducted on a meso-macro tidal beach, Yintan Beach, to simultaneously detect the characteristics and influence mechanism of bed level changes at intra-tidal and tidal cycle scales. The collected data included water depth, suspended sediment concentration (SSC), waves, high-frequency three-dimensional (3-D) velocity, and the distance of the seabed to the acoustic Doppler velocimeter (ADV) probe, which were measured by an optical backscatter sensor, two Tide &amp; Wave Recorder-2050s, and an ADV, respectively. The results showed that the tidal cycle-averaged bed level decreased by 58.8 mm, increased by 12.6 mm, and increased by 28.9 mm during neap, middle, and spring tides in succession, respectively, compared with the preceding tidal regimes. The net erosion mainly resulted from large incident wave heights and the consequent strong offshore-directed sediment transport induced by undertows. Moreover, the variations in the bed level were more prominent during a neap to middle tides than during middle to spring tides, which were jointly caused by the wave-breaking probability regulated by water depth and the relative residence times of shoaling wave, breaker, and surf zones that were determined by relative tidal range. In terms of the intra-tidal bed level, it displayed an intra-tidal tendency of increase during floods and decrease during ebb tides, i.e., the intra-tidal bed level changes were controlled by water depth, which modulated the effects of waves on sediment resuspension and vertical sediment exchange. To be specific, waves and SSC were responsible for the intra-tidal bed level changes under low-energy wave conditions, while mean current and bedform exerted important influences on the variations of the intra-tidal bed level under moderate wave conditions, which broke the foregoing interrelation between bed level, waves, and SSC. This study, therefore, emphasizes the usage of ADV measurement to investigate bed level changes in sandy coasts.

Meng Xia, Tom Carruthers, Richard Kindong et al.

Fisheries researchers have focused on the value of information (VOI) in fisheries management and trade-offs since scientists and managers realized that information from different resources has different contribution in the management process. We picked seven indicators, which are log-normal annual catch observation error (Cobs), annual catch observation bias (Cbias), log-normal annual index observation error (Iobs), maximum length observation bias (Linfbias), observed natural mortality rate bias (Mbias), observed von Bertalanffy growth parameter K bias (Kbias), and catch-at-age sample size (CAA_nsamp), and built operating models (OMs) to simulate fisheries dynamics, and then applied management strategy evaluation (MSE). Relative yield is chosen as the result to evaluate the contribution of the seven indicators. Within the parameter range, there was not much information value reflected from fisheries-dependent parameters including Cobs, Cbias, and Iobs. On the other hand, for fisheries-independent parameters such as Kbias, Mbias, and Linfbias, similar tendency of the information value was showed in the results, in which the relative yield goes down from the upper bound to the lower bound of the interval. CAA_nsamp had no impact on the yield after over 134 individuals. The VOI analysis contributes to the trade-offs in the decision-making process. Information with more value is more worthy to collect in case of waste of time and money so that we could make the best use of scientific effort. But we still need to improve the simulation process such as enhancing the diversity and predictability in an OM. More parameters are on the way to be tested in order to collect optimum information for management and decision-making.

Glen S. Brown, Philip D. DeWitt, Neil Dawson et al.

Conservation of communities of wildlife may conflict with forestry due to the impacts of habitat alteration to wildlife and desire by the public for economic development. Identification of thresholds to disturbance and habitat conditions may improve our ability to find compromises between conservation and resource development, while also identifying sensitive indicators. We used the multivariate Threshold Indicator Taxa Analysis (TITAN) to assess the response of a wildlife community to disturbance from forest harvest, roads, and forest habitat affected by forest management. Significant thresholds were evident among birds, amphibians and mammals, and patterns in positive and negative responses appeared to vary in relation to life history adaptations. Birds typically had the strongest relationships to environmental gradients and provided good representation of a range of forest conditions useful in assessing sustainability in forestry. We found that negative indicator responses to forest habitat gradients were often more precise and synchronous among species than positive responses, potentially affected by the diversity of habitat niche space among species. Stronger responses among a greater range of species were evident for resource-providing habitat conditions than direct measures of disturbance (i.e. forest cuts and roads). Our approach demonstrates the value of identifying ecological community thresholds that can serve to set targets for conserving biodiversity and to characterize community dynamics in response to habitat change mediated by natural resource management.

Stephane Caut, Vincent Francois, Matthieu Bacques et al.

The black caiman is one of the largest neotropical top predators, which means that it could play a structuring role within swamp ecosystems. However, because of the difficulties inherent to studying black caimans, data are sorely lacking on many aspects of their general biology, natural history, and ecology, especially in French Guiana. We conducted a detailed study of the Agami Pond black caiman population using a multidisciplinary approach. The aim was to better understand the species' dietary ecology and movements in the pond, and thus its functional role in pond system. We gathered natural history data, tracked caiman movements using satellite transmitters, and characterized feeding ecology via stable isotope analysis. Our study was carried out over three sampling periods and spanned both wet and dry seasons, which differ in their hydrological and ecological conditions. Our results show that black caiman abundance and age demographics differed between seasons in Agami Pond. In the dry season, Agami Pond is one of the only areas within the marsh to hold water. It thus contains large quantities of different fish species, which form the basis of the black caiman's diet. Caiman body size, a proxy for age class, was around 1.5 meters. During the wet season, which corresponds to the breeding period for migratory birds (e.g., Agami herons), adult black caimans are present in Agami Pond. Adults were most abundant in the inundated forest. There, most individuals measured up to 2 meters. They also exhibited a particular "predatory" behavior near bird nests, preying on fallen chicks and adults. Juveniles and subadults were present during both seasons in the pond's open waters. These behavioral observations were backed up by stable isotope analysis, which revealed ontogenetic variation in the caiman's isotopic values. This isotopic variation reflected variation in diet that likely reduced intraspecific competition between adults and young. The telemetry and microchip data show that different age classes had different movement patterns and that seasonal variation in the pond may influence caiman prey availability and reproductive behavior. The new information gathered should help predict this species' responses to potential ecosystem disturbance (e.g., water pollution, habitat destruction) and inform the development of an effective conservation plan that involves locals and wildlife officials.

Paolo Casula

The Great Capricorn beetle, Cerambyx cerdo, and Mediterranean oak habitats (Quercus ilex – 9340 and Quercus suber – 9330) are protected by the Habitats Directive (HD). However, in the Mediterranean basin, these habitats are also traditionally used for animal, wood, and cork productions. Cerambyx cerdo feeds into the wood of trees and can be perceived by forest practitioners as an umbrella species or as a pest, depending on the context. Monitoring programmes involving forest practitioners could thus focus on assessing: 1) the conservation status of the Great Capricorn beetle and habitats (distribution and abundance of insects and reproductive sites or colonised trees), 2) pest status, and 3) management options to achieve both conservational and economic benefits. Considering that Cerambyx cerdo and Cork and Holm oak forests are not priority species or habitats under the HD, targeted funding is likely to be limited for monitoring. In this context, citizen science could gather important information on the target species useful for the monitoring programmes and management. To address management questions, the citizen science based programme for Cerambyx cerdo monitoring and habitat conservation should be seen not only as citizens collecting good data sets, but also as a deeper collaboration amongst different knowledge bodies and perspectives within a community – based environmental monitoring and learning network.

Jennifer L. Reidy, Lisa O'Donnell, Frank R. Thompson III

ABSTRACT It is critically important to determine and understand relationships between endangered species populations and landscape and habitat features to effectively manage and conserve populations and the habitats they rely on. Several recent studies focused on the golden‐cheeked warbler (Setophaga chrysoparia), an endangered songbird that breeds exclusively in central Texas, USA, have used a reproductive index to link pairing and breeding success to various factors of interest. However, no field test has evaluated the performance of a reproductive index at estimating productivity of golden‐cheeked warblers or similar forest songbirds. We computed reproductive index ranks for 5 observers from multiple plots during 2013 and 2014 and compared these ranks with actual reproductive success determined from territory mapping and nest monitoring of color‐banded adults. At the territory level, we found no significant correlation between 84 matched territories delineated by the reproductive index and territories delineated by intensive monitoring. At the plot level, index monitoring underestimated the total number of territorial males, but density from index monitoring was weakly correlated with actual density. We found no significant relationship for pairing success estimated from the reproductive index and actual pairing success, or with breeding success from the reproductive index with nest survival or actual breeding success, when controlling for observer. The reproductive index did not produce reliable estimates of reproductive performance at either the territory or plot level and we recommend intensive monitoring of color‐banded individuals when absolute estimates of reproductive success rates or other demographic measures are required, such as in species viability or threat assessments. © 2015 The Wildlife Society.

Mariana F.G. Assunção, Sandrine da Ressurreição

Due to the toxicity of synthetic antioxidants, the demand for alternative sources of antioxidants over the years has increased. The interest in such compounds is related to their importance in human health and food quality. Microalgae, a group of organisms with high morphological diversity and able to produce a wide variety of biochemical compounds are considered a promising, non expensive source of antioxidant compounds (Guedes <i>et al</i>., 2013a). This work reports the screening of several different species of microalgae for their antioxidant behavior using the 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid radical cation (ABTS•+) spectrophotometric assay for antioxidant activity (Guedes <i>et al</i>., 2013b) to 50 microalgae from the Coimbra Collection of Algae (ACOI). This method is based on the discoloration of a radical solution expressed as a radical inhibition activity. Recorded values obtained varied between 0.19 and 12.31 mg.L1 equivalent ascorbic acid concentration. In order to confirm the results, the initial screening was followed by the application of the ABTS•+ assay and another common method for antioxidant activity namely that using 2,2-diphenyl-1-picrylhydrazyl (DPPH•) to 8 selected strains from the first 50 and belonging to different taxonomic groups. The DPPH• method consists on the decrease of absorbance of a solution containing the radical in the presence of antioxidants (Brand-Williams <i>et al</i>., 1994). The results obtained for these 8 strains ranged from 2 to 30 mg.L-1 equivalent ascorbic acid concentration for the ABTS•+ assay and from 7 to 13% inhibition of DPPH•. Both sets of results indicate an interesting antioxidant potential in microalgae belonging to the groups Eustigmatophyceae and Chlorophyceae. Tested species of these groups showed ABTS•+ values comparable to grape and raspberry ethanolic extracts, confirmed also by the DPPH• method.

Christian T. K.-H. Stadtlander

N. Löffel, L. Rossi, M. Mumenthaler et al.