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Hormesis shifts the no-observed-adverse-effect level (NOAEL)

Journal Paper
Agathokleous E., Saitanis C.J. AND Markouizou A.
Dose-Response (Accepted)
Publication year: 2021

Data from recent dose-response toxicological studies suggest that the no-observed-adverse-effect-level (NOAEL) may depend upon whether hormesis is present. A further examination of these data supports this hypothesis by showing that the NOAEL was greater for living units (organisms or cells) showing hormesis than for living units showing no hormesis. For example, some cancer tissue cells may exhibit hormetic responses to an anticancer drug while some other cancer tissue cells may not. These findings suggest that living units showing hormesis may also be less susceptible than living units not showing hormesis. However, these findings are preliminary and cannot be generalized or assumed to be a norm yet. New studies are needed to evaluate how NOAEL shifts depending on the occurrence of hormesis.

Exogenous application of melatonin to plants, algae, and harvested products to sustain agricultural productivity and enhance nutritional and nutraceutical value: A meta-analysis

Journal Paper
Agathokleous, E., Zhou, B., Xu, J., Ioannou, A., Feng, Z., Saitanis, C.J., Frei, M., Calabrese, E.J., and Fotopoulos, V.
Environmental Research (In Press)
Publication year: 2021

Το φαινόμενο της όρμησης στην τοξικολογία (Hormesis phenomenon in Toxicology)

Book Chapter
Αγαθοκλέους Ε., Μαρκουίζου Α., Σαϊτάνης Κ.Ι. (Agathokleous E., Markouizou A., Saitanis C.J.)
Κεφάλαιο 6. Στο: Τσατσάκης Α. Τοξικολογία στο σύγχρονο κόσμο. Ιατρικές Εκδόσεις Νέον. (Chapter 6. In: Tsatsakis A. Toxicology in the modern world. Publisher: Medical Editions Neon ISBN: 978-618-84478-0-6
Publication year: 2020

Plant susceptibility to ozone: A Tower of Babel? 

Journal Paper
Agathokleous, E. and Saitanis, C.J., 
Science of the Total Environment,Volume 703, 134962
Publication year: 2020

Abstract

In a world with climate change and environmental pollution, modern Biology is concerned with organismic susceptibility. At the same time, policy and decision makers seek information about organismic susceptibility. Therefore, information about organismic susceptibility may have far-reaching implications to the entire biosphere that can extend to several forthcoming generations. Here, we review a sample of approximately 200 published peer-reviewed articles dealing with plant response to ground-level ozone to understand how the information about susceptibility is communicated. A fuzzy and often incorrect terminology was used to describe the responsiveness of plants to ozone. Susceptibility was classified too arbitrarily and this was reflected to the approximately 50 descriptive words that were used to characterize susceptibility. The classification of susceptibility was commonly based on calculated probability (p) value. This practice is inappropriate as p values do not provide any basis for effect or susceptibility magnitude. To bridge the gap between science and policy decision making, classification of susceptibility should be done using alternative approaches, such as effect size estimates in conjunction with multivariate ordination statistics.

Ozone Effects on Vegetation: A Walk from Cells to Ecosystems

Book Chapter
Burkey K.O., Agathokleous E., Saitanis C.J., Mashaheet A. M. , Koike T. and Hung Y.-T.
Chapter 10. Ozone Effects on Vegetation: A Walk from Cells to Ecosystems. In: Hung, Y.T., Wang, L.K., and N. Shammas eds. Handbook of Environment and Waste Management, Volume 3: Acid Rain and Greenhouse Gas Pollution Control, pp. 357-396 (ISBN-10: 9811207127). World Scientific Publishing Co. Inc, Singapore, 14 August 2020. DOI: 10.1142/9789811207136_0010
Publication year: 2020

Ozone biomonitoring: A versatile tool for science, education and regulation

Journal Paper
Agathokleous E., Saitanis C.J., Feng Z., De Marco A., Araminiene V., Domingos M., Sicard P., Paoletti E.
Current Opinion in Environmental Science & Health, 18:7-13
Publication year: 2020

Abstract

Ground-level ozone (O3) pollution can adversely affect human health and vegetation, thus being an important environmental issue nowadays. Ozone biological monitoring (biomonitoring) is a method of O3 monitoring by observing quantitative changes in living organisms physically present in a specific environment. Here, we provide a concise view of the field of O3 biomonitoring, along with recent advances that are expected to advance this field in the future. We also recommend that O3 biomonitoring is included in citizen science initiatives as well as in worldwide curricula of educational institutions. Policy-makers and general public may not understand biomonitoring data; hence, a major challenge is how to communicate the information to the audience in a way that permits the best comprehension.

Ozone affects plant, insect and soil microbial communities and threatens terrestrial ecosystems and biodiversity

Journal Paper
Agathokleous E., Feng Z., Oksanen E., Sicard P., Qi Wang1, Saitanis C.J.,  Araminiene V., Blande J.D., Hayes F., Calatayud V., Domingos M., Veresoglou S., Peñuelas J., Wardle D.A., De Marco A., Li Z., Harmens H., Yuan X., Vitale M., Kreft H., Sala O.E., Paoletti E
Science Advances, Vol. 6, no. 33, eabc1176 DOI: 10.1126/sciadv.abc1176
Publication year: 2020

Abstract

Elevated ground-level ozone (O3) pollution can adversely affect plants and inhibit plant growth and productivity, threatening food security and ecological health. It is therefore essential to develop measures to protect plants against O3-induced adverse effects. Here we summarize the current status of phytoprotection against O3-induced adverse effects and consider recent scientific and engineering advances, to provide a novel perspective for maximizing plant health while reducing environmental/ecological risks in an O3-polluted world. We suggest that nanoscience and nanotechnology can provide a new dimension in the protection of plants against O3-induced adverse effects, and recommend that new studies are based upon a green chemistry perspective.

Elevated tropospheric ozone concentrations induce adverse effects in plants. We reviewed how ozone affects (i) the composition and diversity of plant communities by affecting key physiological traits; (ii) foliar chemistry and the emission of volatiles, thereby affecting plant-plant competition, plant-insect interactions, and the composition of insect communities; and (iii) plant-soil-microbe interactions and the composition of soil communities by disrupting plant litterfall and altering root exudation, soil enzymatic activities, decomposition, and nutrient cycling. The community composition of soil microbes is consequently changed, and alpha diversity is often reduced. The effects depend on the environment and vary across space and time. We suggest that Atlantic islands in the Northern Hemisphere, the Mediterranean Basin, equatorial Africa, Ethiopia, the Indian coastline, the Himalayan region, southern Asia, and Japan have high endemic richness at high ozone risk by 2100.

On the atmospheric ozone monitoring methodologies

Journal Paper
Saitanis J.C., Sicard P., De Marco A., Feng Z., Paoletti E., Agathokleous E.
Current Opinion in Environmental Science & Health, Volume 18, Pages 40-46
Publication year: 2020

Abstract

Elevated ground-level ozone (O3) pollution can adversely affect plants and inhibit plant growth and productivity, threatening food security and ecological health. It is therefore essential to develop measures to protect plants against O3-induced adverse effects. Here we summarize the current status of phytoprotection against O3-induced adverse effects and consider recent scientific and engineering advances, to provide a novel perspective for maximizing plant health while reducing environmental/ecological risks in an O3-polluted world. We suggest that nanoscience and nanotechnology can provide a new dimension in the protection of plants against O3-induced adverse effects, and recommend that new studies are based upon a green chemistry perspective.

Ozone (O3) is a natural component of the atmosphere. It occurs in the stratosphere, where it protects biota against ultraviolet radiation, but also in the lower troposphere, where it can directly harm biota. Because of its (i) high toxicological potential for biota, (ii) high reactivity and molecular instability, and (iii) difficult differentiation from other reactive oxygen species, O3 challenges scientists in a continuing effort to develop methods for its monitoring. We present here the operation principles of the most used techniques, along with some new technological developments for atmospheric O3 monitoring, with emphasis upon near surface. Huge amounts of scientific data have been produced thanks to progresses in O3 monitoring technologies. However, it remains a challenge to further develop reliable methods with rapid response and high sensitivity to ambient O3, which will also be free from the disadvantages of the current technologies.

Ground-Level Ozone Profile and the Role of Plants as Sources and Sinks

Book Chapter
Saitanis, C.J., Agathokleous, E., Burkey, K., and Hung, Y.T.
Chapter 8. In: Hung, Y.T., Wang, L.K., and N. Shammas eds. Handbook of Environment and Waste Management, Volume 3: Acid Rain and Greenhouse Gas Pollution Control, pp. 281-324. (ISBN-10: 9811207127). World Scientific Publishing Co. Inc, Singapore, 14 August 2020. DOI: 10.1142/9789811207136_0008
Publication year: 2020

Exogenous application of chemicals for protecting plants against ambient ozone pollution: What should come next?

Journal Paper
Saitanis J.C. and Agathokleous E.
Current Opinion in Environmental Science & Health, 19: 100215
Publication year: 2020

Abstract

Elevated ground-level ozone (O3) pollution can adversely affect plants and inhibit plant growth and productivity, threatening food security and ecological health. It is therefore essential to develop measures to protect plants against O3-induced adverse effects. Here we summarize the current status of phytoprotection against O3-induced adverse effects and consider recent scientific and engineering advances, to provide a novel perspective for maximizing plant health while reducing environmental/ecological risks in an O3-polluted world. We suggest that nanoscience and nanotechnology can provide a new dimension in the protection of plants against O3-induced adverse effects, and recommend that new studies are based upon a green chemistry perspective.

Differential Ozone Responses Identified Among Key Rust Susceptible Wheat Genotypes

Journal Paper
Mashaheet A.M., Burkey K.O., Saitanis C.J., Abdelrhim A.S., Ullah R., Marshall D.S.
Agronomy 2020, 10, 1853.
Publication year: 2020

Abstract

Increasing ambient ozone (O3) concentrations and resurgent rust diseases are two concomitant limiting factors to wheat production worldwide. Breeding resilient wheat cultivars bearing rust resistance and O3 tolerance while maintaining high yield is critical for global food security. This study aims at identifying ozone tolerance among key rust-susceptible wheat genotypes [Rust near-universal susceptible genotypes (RnUS)], as a first step towards achieving this goal. Tested RnUS included seven bread wheat genotypes (Chinese Spring, Line E, Little Club, LMPG 6, McNair 701, Morocco and Thatcher), and one durum wheat line (Rusty). Plants were treated with five O3 concentrations (CF, 50, 70, 90, and 110 ppb), in two O3 exposure systems [continuous stirred tank reactors (CSTR) and outdoor-plant environment chambers (OPEC)], at 21–23 Zadoks decimal growth stage. Visible injury and biomass accumulation rate were used to assess O3 responses. Visible injury data showed consistent order of genotype sensitivity (Thatcher, LMPG 6 > McNair 701, Rusty > Line E, Morocco, Little Club > Chinese Spring). Additionally, leaves at different orders showed differential O3 responses. Biomass accumulation under O3 stress showed similar results for the bread wheat genotypes. However, the durum wheat line “Rusty” had the most O3-sensitive biomass production, providing a contrasting O3 response to the tolerance reported in durum wheat. Chinese Spring was the most tolerant genotype based on both parameters and could be used as a source for O3 tolerance, while sensitive genotypes could be used as sensitive parents in mapping O3 tolerance in bread wheat. The suitability of visible symptoms and biomass responses in high-throughput screening of wheat for O3 tolerance was discussed. The results presented in this research could assist in developing future approaches to accelerate breeding wheat for O3 tolerance using existing breeding materials.

Ambient Ozone Alternative Monitoring And Biomonitoring With Higher Plants

Book Chapter
Saitanis C.J., Burkey K.O., Agathokleous E., and Hung Y.-T.
Chapter 9. In: Hung, Y.T., Wang, L.K., and N. Shammas eds. Handbook of Environment and Waste Management, Volume 3: Acid Rain and Greenhouse Gas Pollution Control, pp. 325-356 (ISBN-10: 9811207127). World Scientific Publishing Co. Inc, Singapore, 14 August 2020. DOI: 10.1142/9789811207136_0009
Publication year: 2020

Study of the effect of different rootstocks on the growth and production of beans grown under increased salinity conditions

National Conference
Vougelekas V., Datsi G., Mylonas F., TabakakiA., Saitanis K.I., Savvas D.
Scientific Conference of EEEO. Research Applications and Leading Technologies in Plant Production. Patras 15-18 Oct. 2019. Book of Abstracts, p. 211
Publication year: 2019

Stress response and population dynamics: Is Allee effect hormesis?

Journal Paper
Saitanis C.J., and Agathokleous E.
Science of the Total Environment, 682, pp. 623-628
Publication year: 2019

Abstract

Hormesis is a fundamental notion in ecotoxicology while competition between organisms is an essential notion in population ecology and species adaptation and evolution. Both sub-disciplines of ecology deal with the response of organisms to abiotic and biotic stresses. In ecotoxicology, the Linear-non-Threshold (LNT), Threshold and Hormetic models are used to describe the dominant responses of a plethora of endpoints to abiotic stress. In population ecology, the logistic, theta-logistic and the Allee effect models are used to describe the growth of populations under different responses to (biotic) stress induced by population density. The per capita rate of population increase (r) measures species fitness. When it is used as endpoint, the responses to population density seem to perfectly correspond to LNT, Threshold and Hormetic responses to abiotic stress, respectively. Our analysis suggests the Allee effect is a hormetic-like response of r to population density, an ultimate biotic stress. This biphasic dose-response model appears across different systems and situations (from molecules to tumor growth to population dynamics), is highly supported by ecological and evolutionary theory, and has important implications in most sub-disciplines of biology as well as in environmental and earth sciences. Joined multi-disciplinary efforts would facilitate the development and application of advanced research approaches for better understanding potential planetary-scale implications.

Predicting the effect of ozone on vegetation via the linear non-threshold (LNT), threshold and hormetic dose-response models

Journal Paper
Agathokleous, E., Belz, R.G., Calatayud, V., De Marco, A., Hoshika, Y., Kitao, M., Saitanis, C.J., Sicard, P., Paoletti, E., Calabrese, E.J.
Science of the Total Environment 649: 61-74.
Publication year: 2019

Abstract

The nature of the dose-response relationship in the low dose zone and how this concept may be used by regulatory agencies for science-based policy guidance and risk assessment practices are addressed here by using the effects of surface ozone (O3) on plants as a key example for dynamic ecosystems sustainability. This paper evaluates the current use of the linear non-threshold (LNT) dose-response model for O3. The LNT model has been typically applied in limited field studies which measured damage from high exposures, and used to estimate responses to lower concentrations. This risk assessment strategy ignores the possibility of biological acclimation to low doses of stressor agents. The upregulation of adaptive responses by low O3 concentrations typically yields pleiotropic responses, with some induced endpoints displaying hormetic-like biphasic dose-response relationships. Such observations recognize the need for risk assessment flexibility depending upon the endpoints measured, background responses, as well as possible dose-time compensatory responses. Regulatory modeling strategies would be significantly improved by the adoption of the hormetic dose response as a formal/routine risk assessment option based on its substantial support within the literature, capacity to describe the entire dose-response continuum, documented explanatory dose-dependent mechanisms, and flexibility to default to a threshold feature when background responses preclude application of biphasic dose responses.

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