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result(s) for
"Kalantzi, Olga-Ioanna"
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Floral volatiles and visitors: A meta-network of associations in a natural community
by
Petanidou, Theodora
,
Lekkas, Themistokles
,
Kantsa, Aphrodite
in
Allelochemicals
,
Andrenidae
,
Apidae
2019
1. Chemosensory communication between flowers and pollinators is a fundamental component of terrestrial biodiversity, given the importance of olfaction to foraging animals. In this respect, exploring chemically mediated interspecific interactions in natural assemblies may provide novel insights into the ecofunctional significance of volatile organic compounds (VOCs) for plant-insect co-evolution. However, multispecies datasets of associations between plant semiochemicals and arthropods are still very rare and tend to lack community context. Here, we present the first insect-floral VOC meta-network using plant-pollinator visitation data and the plants' floral scent blends, collected in a Mediterranean scrubland. 2. We assembled the insect-VOC meta-network by substituting each plant species in the plant-pollinator network with the blend of VOCs it emits. Furthermore, we identified the modules of the network that is the most densely connected insectVOC groups. After describing the role of the species in the network, we focused on the bees of the community, and by building phylogenetically informed GLS models, we found the species traits predicting the degree of chemical specialization. 3. Modularity analysis of the meta-network revealed tight associations between several classes of VOCs and pollinator groups. Linkage patterns suggest positive associations between (a) Megachilidae bees and sesquiterpenes, (b) Apidae and Andrenidae bees and benzenoids/phenylpropanoids, and (c) wasps, C6 green-leaf volatiles and specific terpenoids. Benzenoids were found to be the least influential and most specialized chemical class in the community, whereas sesquiterpenes represented the most influential one. Furthermore, the degree of chemical generalization of the bees in the meta-network was significantly associated with their ecological generalization, body mass and phenology, whereas their contribution to the network's structure was related to their level of sociality. 4. Synthesis. Our findings help to disclose the ecofunctional significance of the floral volatile landscape and contribute novel testable hypotheses on the behavioural trends and chemical niches of pollinators in a natural community. The insect-volatilome meta-network is thus shown to be advantageous for detecting and visualizing patterns of chemically mediated interspecific interactions. Given the ubiquity of chemosensory biocommunication, our approach can be applied for investigating various types of ecological interactions in community contexts.
Journal Article
Endocrine Disruptors Acting on Estrogen and Androgen Pathways Cause Reproductive Disorders through Multiple Mechanisms: A Review
by
Mamoulakis, Charalampos
,
Zachariou, Athanasios
,
Kalantzi, Olga-Ioanna
in
Androgens - toxicity
,
Endocrine Disruptors - toxicity
,
Estrogens - toxicity
2021
Increasing contamination of the environment by toxic compounds such as endocrine disrupting chemicals (EDCs) is one of the major causes of reproductive defects in both sexes. Estrogen/androgen pathways are of utmost importance in gonadal development, determination of secondary sex characteristics and gametogenesis. Most of the EDCs mediate their action through respective receptors and/or downstream signaling. The purpose of this review is to highlight the mechanism by which EDCs can trigger antagonistic or agonistic response, acting through estrogen/androgen receptors causing reproductive defects that lead to infertility. In vitro, in vivo and in silico studies focusing on the impact of EDCs on estrogen/androgen pathways and related proteins published in the last decade were considered for the review. PUBMED and PUBCHEM were used for literature search. EDCs can bind to estrogen receptors (ERα and ERβ) and androgen receptors or activate alternative receptors such as G protein-coupled receptors (GPCR), GPR30, estrogen-related receptor (ERRγ) to activate estrogen signaling via downstream kinases. Bisphenol A, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethylene, polychlorinated biphenyls and phthalates are major toxicants that interfere with the normal estrogen/androgen pathways leading to infertility in both sexes through many ways, including DNA damage in spermatozoids, altered methylation pattern, histone modifications and miRNA expression.
Journal Article
Can disc diffusion susceptibility tests assess the antimicrobial activity of engineered nanoparticles?
by
Valenti, Marco
,
Olga-Ioanna Kalantzi
,
Erwin van Rijn
in
Antibacterial activity
,
Antimicrobial activity
,
Antimicrobial agents
2018
The use of disc diffusion susceptibility tests to determine the antibacterial activity of engineered nanoparticles (ENPs) is questionable because their low diffusivity practically prevents them from penetrating through the culture media. In this study, we investigate the ability of such a test, namely the Kirby-Bauer disc diffusion test, to determine the antimicrobial activity of Au and Ag ENPs having diameters from 10 to 40 nm on Escherichia coli cultures. As anticipated, the tests did not show any antibacterial effects of Au nanoparticles (NPs) as a result of their negligible diffusivity through the culture media. Ag NPs on the other hand exhibited a strong antimicrobial activity that was independent of their size. Considering that Ag, in contrast to Au, dissolves upon oxidation and dilution in aqueous solutions, the apparent antibacterial behavior of Ag NPs is attributed to the ions they release. The Kirby-Bauer method, and other similar tests, can therefore be employed to probe the antimicrobial activity of ENPs related to their ability to release ions rather than to their unique size-dependent properties.
Journal Article
Can Campus Green Spaces Be Restorative? A Case Study from Tanzania
by
Vardaka, Maria Lydia
,
Malesios, Chrisovaladis
,
Katima, Zainab Jamidu
in
Case studies
,
College campuses
,
Demographics
2024
Evidence from studies in the global north has shown the beneficial effects of green spaces (GS) for our psychological and physiological health. In this study, we examine whether the connection between GS, wellbeing, and restoration is also applicable to low/middle-income countries (LMICs), using Tanzania as a case study. During May–July 2021, an online survey was conducted among 108 students and/or staff of the University of Dar es Salaam. Information was provided regarding exposure to campus’s green spaces (CGSs) measured by the NDVI and subjective questions relevant to accessibility/availability of CGS, duration and frequency of visits, as well as perceived greenness. Self-reported questions were also used for assessing the quality of CGSs and motives for using them. Mental wellbeing and restoration were measured with the Warwick–Edinburgh Mental Wellbeing Short Scale ((S)WEMWBS) and the Restoration Outcome Scale (ROS), respectively, while the Nature Relatedness Scale (NR-6) was used to determine the feelings and thoughts of our participants towards nature. Generalized linear regression indicated a positive relationship between the need to be close to nature and relaxation as motivators for visiting CG; (S)WEMWBS (p < 0.05). The same correlation was observed for the ROS (p < 0.01). The ROS was also positively associated with the NDVI (p < 0.01), age group of 18–25 (p < 0.05), and employment status (full time p < 0.01, part time p < 0.05). Our findings confirm that GS can be considered an effective tool for promoting SDG 3 and SDG 11 in LMICs. More importantly, urban planners should focus on the motives for using such places in order to make them inclusive and multifunctional.
Journal Article
Perfluoroalkyl and polyfluoroalkyl substances in sewage sludge: challenges of biological and thermal treatment processes and potential threats to the environment from land disposal
by
Arvaniti, Olga S.
,
Stasinakis, Athanasios S.
,
Vakalis, Stergios
in
Africa
,
Agricultural land
,
Anaerobic conditions
2024
Sewage treatment plants are considered as important pathways for the transfer of perfluoroalkyl and polyfluoroalkyl substances (PFAS) to the environment. In conventional wastewater treatment, some of these compounds accumulate in sewage sludge via sorption onto suspended solids posing a potential environmental threat during sludge disposal and reuse. This review paper summarizes data for the occurrence of 182 PFAS from different classes in sludge matrices. Most of these monitoring data originate from Europe, Asia and North America, while limited data are available from Africa and South America. The most commonly studied classes of PFAS are perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, and perfluoroalkyl sulfonamides, while few results are available for the occurrence of new generation PFAS such as GenX. The range of the observed concentrations varies between 0.01 ng/g d.w. for perfluorobutane sulfonic acid to some μg/g, depending on the compound, with the highest concentrations found for perfluorooctane sulfonic acid (8.2 μg/g d.w.). Limited information exists for the fate and removal of these substances in full-scale anaerobic digesters while recent articles indicate that some PFAS can be biotransformed under strictly anaerobic conditions. The exact mechanism remains unclear; additional data are needed to identify transformation products, apply mass balances, and understand the role of specific microorganisms. As regards novel thermal processes, encouraging results were recently published for the destruction of specific PFAS in hydrothermal liquefaction and carbonization, ranging between 55 and 100%, depending on the compound and the experimental conditions applied. Future studies should expand the list of studied compounds and focus on the mechanisms of their removal. PFAS are transferred to agricultural lands during sewage sludge reuse and their concentrations in soil are related to the applied biosolids’ loading rates. The parameters that affect leaching and desorption of PFAS from sludge, their plant uptake and possible threats for the environment and human health from the use of sewage sludge as soil amendment should be examined in long-term studies. ZeroPM project aims to address some of the literature gaps regarding the behavior of PFAS during sludge treatment focusing to the modification of anaerobic digestion and to the use of hydrothermal carbonization.
Journal Article
Keep Calm and Go Out: Urban Nature Exposure, Mental Health, and Perceived Value during the COVID-19 Lockdown
by
Kokkinaki, Margarita
,
Sinvare, Marios-Dimitrios
,
Malesios, Chrisovalantis
in
Air pollution
,
Anxiety
,
China
2023
The COVID-19 pandemic has highlighted the importance of incorporating nature-based solutions in urban design, in order to create sustainable and resilient cities. Inspired by these events, the present study aims at exploring the mental health benefits of nature exposure during the outbreak. Secondarily, we investigate changes in use patterns towards urban green spaces (UGS) and urban blue spaces (UBS) and whether extreme conditions, such as these of a lockdown, can lead to an increase in people’s appreciation of urban nature. Through an online survey, we observed that the pandemic resulted in a decrease in the frequency of visitation to UGS/UBS (p < 0.001). Significant differences were found for exercise (p < 0.001) and socialization (p < 0.05) as main drivers for visiting urban nature pre- and post-lockdown. Accordingly, visitation rates for forests (p < 0.05), playgrounds (p < 0.001), and the sea (p < 0.001) differed significantly when comparing the two periods. In people’s perception, UGS/UBS are important for the urban fabric (89%). Our structural equation model indicated that nature exposure had a beneficial effect on participants’ mental health (p < 0.001). Pathways that explain the relationship between nature exposure and post- lockdown value were nature relatedness, motivation, and perceived importance of UGS/UBS. No mediation could be extracted for nature exposure and mental health. Our findings show the positive association between nature exposure and mental health improvement, especially in times of crisis, as well as a shift in the “value domain” towards urban nature.
Journal Article
Occurrence and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in dust of an emerging industrial city in Iran: implications for human health
by
Hajiali Begloo, Raziyeh
,
Khamoshi, Seyyed Erfan
,
Aminiyan, Milad Mirzaei
in
Adult
,
Anthracene
,
anthracenes
2021
Polycyclic aromatic hydrocarbons (PAHs) bounded to street dust are a severe environmental and human health danger. This study provides preliminary information on the abundance of PAHs in street dust from Rafsanjan city, Iran, where industrial emissions are high and data are lacking. Seventy street dust samples were collected from streets with different traffic loads. The United States Environmental Protection Agency (USEPA) Standard Methods 8270D and 3550C were used for the measurement of PAHs using GC mass spectroscopy. The total concentration of PAHs was 1443 ng g
−1
, with a range of 1380–1550 ng g
−1
. Additionally, the concentration of carcinogenic PAHs (∑
carc
PAHs) ranged from 729.5 to 889.4 ng g
−1
, with a mean value of 798.1 ng g
−1
. Pyrene was the most abundant PAH, with an average concentration of 257 ng g
−1
. Source identification analyses showed that vehicle emissions along with incomplete combustion and petroleum were the main sources of PAHs. The ecological risk status of the studied area was moderate. Spatial distribution mapping revealed that the streets around the city center and oil company had higher PAH levels than the other sectors of Rafsanjan. The results indicated that dermal contact and ingestion of contaminated particles were the most important pathways compared to inhalation. The mean incremental lifetime cancer risk (ILCR) was 1.4 × 10
−3
and 1.3 × 10
−3
for children and adults, respectively. This implies potentially adverse health effects in exposed individuals. The mutagenic risk for both subpopulations was approximately 18 times greater than the one recommended by USEPA. Our findings suggest that children are subjected to a higher carcinogenic and mutagenic risk of PAHs, especially dibenzo[a,h]anthracene (DahA), bounded to street dust of Rafsanjan. Our study highlights the need for the development of emission monitoring and control scenarios.
Journal Article
Engaging the Senses: The Association of Urban Green Space with General Health and Well-Being in Urban Residents
by
Dimitrakopoulos, Panayiotis G.
,
Chrousos, George P.
,
Kanelli, Argyro Anna
in
Air pollution
,
Blood pressure
,
Emotions
2021
This study evaluated the short-term responses of physiological and psychological indices and examined the human senses that are mostly engaged during a green space and urban exposure in residents of Athens, Greece. The forest had beneficial effects for human physiology, anxiety and mood states and was also associated with all five senses and positive reactions, while the opposite was observed in the urban center. The difference of pre- and post-green space exposure salivary cortisol was correlated with the participants’ environmental profile and body mass index. Green spaces can alleviate stress and improve overall mood, while helping individuals experience their surroundings with all five senses.
Journal Article
Methods for Assessing Basic Particle Properties and Cytotoxicity of Engineered Nanoparticles
2014
The increasing penetration of materials and products containing engineered nanoparticles (ENPs) to the market is posing many concerns regarding their environmental impacts. To assess these impacts, there is an urgent need of techniques for determining the health-related properties of ENPs and standards for assessing their toxicity. Although a wide number of systems for characterizing nanoparticles in different media (i.e., gases and liquids) is already commercially available, the development of protocols for determining the cytotoxicity of ENPs is still at an infant stage, drawing upon existing knowledge from general toxicology. In this regard, differences in the preparation of ENP-containing solutions for cytotoxicity testing, as well as in the steps involved in the tests can result in significant deviations and inconsistencies between studies. In an attempt to highlight the urgent need for assessing the environmental impacts of nanotechnology, this article provides a brief overview of the existing methods for determining health-related properties of ENPs and their cytotoxicity.
Journal Article
Stakeholders Perceptions of Non-indigenous Freshwater Fish Species: A Case Study from a Mediterranean Biodiversity Hotspot
by
Olga-Ioanna, Kalantzi
,
Perdikaris Costas
,
Vardakas Leonidas
in
Aquatic ecosystems
,
Biodiversity
,
Biodiversity hot spots
2022
Even though the ecological impacts of invasive alien species (IAS) have been well studied, social aspects of IAS in freshwater ecosystems are still poorly explored. This study aimed to assess the perceptions associated with non-indigenous freshwater fish species (NIFS) among environmental-related professional and non-professional stakeholders in a Mediterranean country that displays high levels of fish species endemism, by using a questionnaire survey approach. Overall, 203 individuals participated, from which, the majority (n = 144) were related to environmental sciences. Most of the respondents perceived NIFS to be a threat of national importance, possibly attributed to the emotional effect of the term non-indigenous (conceived as intruder). However, NIFS were indicated as the least important threat affecting aquatic ecosystems when compared with other pressures. This contrasting perception could be explained by the fact that broad-scale impacts (i.e., climate change) exert stronger reactions compared to NIFS. Interestingly, non-professionals were more successful in identifying NIFS and native species compared to professionals, however both indicated low overall identification success. The majority of the respondents, both professionals and non-professionals, considered that: (a) the official authorities do not implement actions for NIFS management, (b) government spending should be increased to manage NIFS even if it should be reduced for other needs, and (c) early detection is the best way to manage NIFS. The establishment of a nationwide network consisting of all related stakeholders on NIFS issues, aiming to public awareness and preventive management actions to limit the spread and impacts of NIFS should be set as a priority.
Journal Article