PeerJ Preprints: Ecotoxicologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1409Ecotoxicology articles published in PeerJ PreprintsMicroevolutionary processes on railway tracks in Geranium robertianum populationshttps://peerj.com/preprints/277932019-06-112019-06-11Olga Bemowska-KałabunPaweł WąsowiczŁukasz Napora-RutkowskiZuzanna Nowak-ŻyczyńskaMałgorzata Wierzbicka
A strongly modified habitat can be treated as “research field”, where microevolutionary processes in plants take place and can be traced. One of such areas are railway tracks. Difficult conditions for plant growth prevail there, including: insolation, water shortage and pollutions. This leads to natural selection, which favors microevolutionary processes. Geranium robertianum L. plants were tested, which occur on railway tracks (“track populations”) and in forests (“forest populations”), of north-eastern Poland. Totally, the phenotypic and genotypic diversity was checked in 20 track populations and 18 forest populations. The aim of the research was to check what was the taxonomic rank of a different biotype of G. robertianum, which is growing on the railway tracks in the village of Waliły-Station. The plants from this population in comparison to other studied populations were: smaller, had much smaller (about twice) and darker leaves with an increased level of anthocyanins (higher by a few – over a dozen % from plants from other track populations and about 50% from plants from forest populations). These features were preserved in the next generation (F1). However, molecular studies (AFLP) showed that the population from Waliły was not genetically distinct from other studied populations. The taxonomic rank of G. robertianum plants from the track population of Waliły-Station should be described as “form”. It is possible that this new form of G. robertianum plants could have arisen as a result of the occurrence of epigenetic processes, which could increase the phenotypic variability in G. robertianum and accelerate the adaptation of these plants to adverse conditions. The obtained results are an example of the initial stage of the process of microevolution in plants in anthropogenically transformed areas.
A strongly modified habitat can be treated as “research field”, where microevolutionary processes in plants take place and can be traced. One of such areas are railway tracks. Difficult conditions for plant growth prevail there, including: insolation, water shortage and pollutions. This leads to natural selection, which favors microevolutionary processes. Geranium robertianum L. plants were tested, which occur on railway tracks (“track populations”) and in forests (“forest populations”), of north-eastern Poland. Totally, the phenotypic and genotypic diversity was checked in 20 track populations and 18 forest populations. The aim of the research was to check what was the taxonomic rank of a different biotype of G. robertianum, which is growing on the railway tracks in the village of Waliły-Station. The plants from this population in comparison to other studied populations were: smaller, had much smaller (about twice) and darker leaves with an increased level of anthocyanins (higher by a few – over a dozen % from plants from other track populations and about 50% from plants from forest populations). These features were preserved in the next generation (F1). However, molecular studies (AFLP) showed that the population from Waliły was not genetically distinct from other studied populations. The taxonomic rank of G. robertianum plants from the track population of Waliły-Station should be described as “form”. It is possible that this new form of G. robertianum plants could have arisen as a result of the occurrence of epigenetic processes, which could increase the phenotypic variability in G. robertianum and accelerate the adaptation of these plants to adverse conditions. The obtained results are an example of the initial stage of the process of microevolution in plants in anthropogenically transformed areas.Bioremediation of engine-oil contaminated soil using local residual organic matterhttps://peerj.com/preprints/276962019-04-302019-04-30Kawina RobichaudMiriam LebeauSylvain MartineauMarc Amyot
Soil remediation industries continue to seek technologies to speed-up treatment and reduce operating costs. Some processes are energy intensive and, in some cases, transport can be the main source of carbon emissions. Residual fertilizing matter (RFM), such as organic residues, have the potential to be beneficial bioremediation agents. Following a circular economy framework, we investigated the feasibility of sourcing RFMs locally to reduce transport and assess possible bioremediation efficiency gains. RFMs were recruited within 100 km of the treatment site: ramial chipped wood (RCW), horse manure (MANR) and brewer spent grain (BSG). They were added to the land treatment unit’s baseline fertilizer treatment (FERT, ‘F’) to measure if they improved the remediation efficiency of an engine oil-contaminated soil (7500 ± 100 mg kg-1). Results indicate that MANR-F was the only amendment more effective than FERT for PHC reduction, while emitting the least CO2overall. RCW-F was equivalent to FERT but retained more moisture. Although BSG contributed the most nitrogen to the soil, BSG-F retained excessive moisture, emitted more VOCs, contained less soil O2, and was less effective than the baseline treatment. Significantly more of the C16-C22fraction was removed (63 ± 22%) than all other fractions (C22-C28, C28-C34, C34-C40), which were equally removed. Microbial community-level physiological profiling (CLPP) was conducted with Biolog EcoplatesTM, and catabolic diversity differed between treatments (utilization rates of 31 carbon sources). MANR-F has the potential to increase PHC-remediation speed and efficiency compared to inorganic fertilizer alone. Other RFM promote moisture retention and diverse microbial catabolic activity. A variety of RFM are present across the globe and some can offer low-cost amendments to boost remediation efficiency, while reducing treatment time compared to traditional fertilizer-only methods.
Soil remediation industries continue to seek technologies to speed-up treatment and reduce operating costs. Some processes are energy intensive and, in some cases, transport can be the main source of carbon emissions. Residual fertilizing matter (RFM), such as organic residues, have the potential to be beneficial bioremediation agents. Following a circular economy framework, we investigated the feasibility of sourcing RFMs locally to reduce transport and assess possible bioremediation efficiency gains. RFMs were recruited within 100 km of the treatment site: ramial chipped wood (RCW), horse manure (MANR) and brewer spent grain (BSG). They were added to the land treatment unit’s baseline fertilizer treatment (FERT, ‘F’) to measure if they improved the remediation efficiency of an engine oil-contaminated soil (7500 ± 100 mg kg-1). Results indicate that MANR-F was the only amendment more effective than FERT for PHC reduction, while emitting the least CO2overall. RCW-F was equivalent to FERT but retained more moisture. Although BSG contributed the most nitrogen to the soil, BSG-F retained excessive moisture, emitted more VOCs, contained less soil O2, and was less effective than the baseline treatment. Significantly more of the C16-C22fraction was removed (63 ± 22%) than all other fractions (C22-C28, C28-C34, C34-C40), which were equally removed. Microbial community-level physiological profiling (CLPP) was conducted with Biolog EcoplatesTM, and catabolic diversity differed between treatments (utilization rates of 31 carbon sources). MANR-F has the potential to increase PHC-remediation speed and efficiency compared to inorganic fertilizer alone. Other RFM promote moisture retention and diverse microbial catabolic activity. A variety of RFM are present across the globe and some can offer low-cost amendments to boost remediation efficiency, while reducing treatment time compared to traditional fertilizer-only methods.Variation in the nitrous oxide reductase gene (nosZ)-denitrifying bacterial community in different primary succession stages in the Hailuogou Glacier retreat area, Chinahttps://peerj.com/preprints/274812019-01-122019-01-12Yan BaiXiying HuangXiangrui ZhouQuanju XiangKe ZhaoXiumei YuQiang ChenHao JiangNyima TashiXue GaoYunfu Gu
Background: The Hailuogou Glacier in the Gongga Mountain region (SW China), on the southeastern edge of the Tibetan Plateau, is well known for its low-elevation modern glaciers. Since the end of the Little Ice Age (LIA), the Hailuogou Glacier has retreated continuously due to global warming, primary vegetation succession and soil chronosequence have developed in this retreat area. The retreated area of Hailuogou Glacier has not been strongly disturbed by human activities, thus it is an ideal models for exploring the biological colonization of nitrogen in the primary successional stages of ecosystem. The nosZ gene encodes the catalytic center of nitrous oxide reductase and is an ideal molecular marker in studying the variation in the denitrifying bacterial community.
Methods: Soil properties as well as abundance and composition of the denitrifying bacterial community were determined via chemical analysis, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment length polymorphism (T-RFLP), respectively. The relationships between the nosZ denitrifying bacterial community and soil properties were determined using redundancy analysis (RDA). Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages.
Results: Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Soil pH in the topsoil decreased from 8.42 to 7.19 in the course of primary succession, while soil organic carbon (SOC) and total nitrogen (TN) gradually increased with primary succession. Available phosphorus (AP) and available potassium (AK), as well as potential denitrify activity (PDA), increased gradually and peaked at the 40-year-old site. The abundance of the nosZ denitrifying bacterial community followed a similar trend. The variation in the denitrifying community composition was complex; Mesorhizobium dominated the soil in the early successional stages (0-20 years) and in the mature phase (60 years), with a relative abundance greater than 55%. Brachybacterium was increased in the 40-year-old site, with a relative abundance of 62.74%, while Azospirillum dominated the early successional stages (0-20 years). Redundancy analysis (RDA) showed that the nosZ denitrifying bacterial community correlated with soil available phosphorus and available potassium levels (P < 0.01).
Background: The Hailuogou Glacier in the Gongga Mountain region (SW China), on the southeastern edge of the Tibetan Plateau, is well known for its low-elevation modern glaciers. Since the end of the Little Ice Age (LIA), the Hailuogou Glacier has retreated continuously due to global warming, primary vegetation succession and soil chronosequence have developed in this retreat area. The retreated area of Hailuogou Glacier has not been strongly disturbed by human activities, thus it is an ideal models for exploring the biological colonization of nitrogen in the primary successional stages of ecosystem. The nosZ gene encodes the catalytic center of nitrous oxide reductase and is an ideal molecular marker in studying the variation in the denitrifying bacterial community.Methods: Soil properties as well as abundance and composition of the denitrifying bacterial community were determined via chemical analysis, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment length polymorphism (T-RFLP), respectively. The relationships between the nosZ denitrifying bacterial community and soil properties were determined using redundancy analysis (RDA). Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages.Results: Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Soil pH in the topsoil decreased from 8.42 to 7.19 in the course of primary succession, while soil organic carbon (SOC) and total nitrogen (TN) gradually increased with primary succession. Available phosphorus (AP) and available potassium (AK), as well as potential denitrify activity (PDA), increased gradually and peaked at the 40-year-old site. The abundance of the nosZ denitrifying bacterial community followed a similar trend. The variation in the denitrifying community composition was complex; Mesorhizobium dominated the soil in the early successional stages (0-20 years) and in the mature phase (60 years), with a relative abundance greater than 55%. Brachybacterium was increased in the 40-year-old site, with a relative abundance of 62.74%, while Azospirillum dominated the early successional stages (0-20 years). Redundancy analysis (RDA) showed that the nosZ denitrifying bacterial community correlated with soil available phosphorus and available potassium levels (P < 0.01).A comparison of acute toxicity methodologies for Bombus spp.https://peerj.com/preprints/274362018-12-182018-12-18Kayla MundyNigel E. Raine
Acute toxicity testing (lethal dose and lethal concentration for 50% of the population; LD50 and LC50) is a required component of the first level of pesticide risk assessment. A review of peer-reviewed and ECOTOX database toxicity values was conducted to assess methodology and toxicity value consistency. Bumble bee LD50 and LC50 tests varied in five key areas: test subject, active ingredient specifications, test solution specifications, test conditions, test procedure. Only recently has a consistent methodology for bumble bee LD50 tests been released, but differs substantially from previous methods. Study methodologies have varied in at least one component and comparison of acute toxicity values can differ substantially between studies. Although a current standard, the appropriateness of the contact LD50 method of anaesthetisation and test location should be revisited. This work demonstrates inconsistency in current peer-reviewed analysis of acute toxicity to bumble bees and that current standard methods may not be perfected.
Acute toxicity testing (lethal dose and lethal concentration for 50% of the population; LD50 and LC50) is a required component of the first level of pesticide risk assessment. A review of peer-reviewed and ECOTOX database toxicity values was conducted to assess methodology and toxicity value consistency. Bumble bee LD50 and LC50 tests varied in five key areas: test subject, active ingredient specifications, test solution specifications, test conditions, test procedure. Only recently has a consistent methodology for bumble bee LD50 tests been released, but differs substantially from previous methods. Study methodologies have varied in at least one component and comparison of acute toxicity values can differ substantially between studies. Although a current standard, the appropriateness of the contact LD50 method of anaesthetisation and test location should be revisited. This work demonstrates inconsistency in current peer-reviewed analysis of acute toxicity to bumble bees and that current standard methods may not be perfected.Copper affects composition and functions of microbial communities in marine biofilms at environmentally relevant concentrationshttps://peerj.com/preprints/271292018-08-202018-08-20Natàlia CorcollJianghua YangThomas BackhausXiaowei ZhangMartin Karl Eriksson
Cu pollution in coastal areas is a worldwide threat for aquatic communities. This study assesses the effects of Cu exposure on microbial diversity, community structure and functions of microbial communities in marine periphyton biofilms at environmental relevant concentrations. Periphyton was exposed for 18 days to five Cu concentrations, between 0.01 and 10 μM, in a semi-static test. Diversity and community structure of prokaryotic and eukaryotic organisms were assessed by 16S and 18S amplicon sequencing, respectively. Community function was studied as impacts on algal biomass and primary production. Additionally, we studied Pollution-Induced Community Tolerance (PICT) using photosynthesis as the endpoint. Sequencing results detected an average of 9504 and 1242 OTUs for 16S and 18S, respectively, reflecting the huge biodiversity of marine periphytic biofilms. Eukaryotes represent the most Cu-sensitive kingdom, where effects were seen already at concentrations as low as 10 nM. The structure of the prokaryotic part of the community was impacted at slightly higher concentrations (60 nM), which is still in the range of the Cu concentrations observed in the area (80 nM).The current environmental quality standard for Cu of 70 nM therefore does not seem to be sufficiently protective for periphyton. Cu exposure resulted in a more Cu-tolerant community, which was accompanied by a reduced total algal biomass, increased relative abundance of diatoms and a reduction of primary production. Cu exposure changed the network of associations between taxa in the communities. A total of 23 taxa, including species within Proteobacteria, Bacteroidetes, Stramenopiles and Hacrobia, were identified as being particularly sensitive to Cu. DNA metabarcoding is presented as a sensitive tool for community-level ecotoxicological studies that allows to observe impacts simultaneously on a multitude of pro- and eukaryotic species, and therefore to identify particularly sensitive, non-cultivable species and taxa.
Cu pollution in coastal areas is a worldwide threat for aquatic communities. This study assesses the effects of Cu exposure on microbial diversity, community structure and functions of microbial communities in marine periphyton biofilms at environmental relevant concentrations. Periphyton was exposed for 18 days to five Cu concentrations, between 0.01 and 10 μM, in a semi-static test. Diversity and community structure of prokaryotic and eukaryotic organisms were assessed by 16S and 18S amplicon sequencing, respectively. Community function was studied as impacts on algal biomass and primary production. Additionally, we studied Pollution-Induced Community Tolerance (PICT) using photosynthesis as the endpoint. Sequencing results detected an average of 9504 and 1242 OTUs for 16S and 18S, respectively, reflecting the huge biodiversity of marine periphytic biofilms. Eukaryotes represent the most Cu-sensitive kingdom, where effects were seen already at concentrations as low as 10 nM. The structure of the prokaryotic part of the community was impacted at slightly higher concentrations (60 nM), which is still in the range of the Cu concentrations observed in the area (80 nM).The current environmental quality standard for Cu of 70 nM therefore does not seem to be sufficiently protective for periphyton. Cu exposure resulted in a more Cu-tolerant community, which was accompanied by a reduced total algal biomass, increased relative abundance of diatoms and a reduction of primary production. Cu exposure changed the network of associations between taxa in the communities. A total of 23 taxa, including species within Proteobacteria, Bacteroidetes, Stramenopiles and Hacrobia, were identified as being particularly sensitive to Cu. DNA metabarcoding is presented as a sensitive tool for community-level ecotoxicological studies that allows to observe impacts simultaneously on a multitude of pro- and eukaryotic species, and therefore to identify particularly sensitive, non-cultivable species and taxa.Triclosan changes community composition and selects for specific bacterial taxa in marine periphyton biofilms in low nanomolar concentrationhttps://peerj.com/preprints/271252018-08-172018-08-17K. Martin ErikssonKemal SanliHenrik NilssonAlexander EilerNatalia CorcollHenrik JohanssonThomas BackhausHans BlanckErik Kristiansson
The antibacterial agent Triclosan (TCS) is an ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division OD1. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum BD1-5. Our results demonstrate the variability of TCS sensitivity among bacteria, and the importance of extending the ecotoxicological assessment of antimicrobial chemicals, such as TCS, to non-cultivable bacteria and natural communities.
The antibacterial agent Triclosan (TCS) is an ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division OD1. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum BD1-5. Our results demonstrate the variability of TCS sensitivity among bacteria, and the importance of extending the ecotoxicological assessment of antimicrobial chemicals, such as TCS, to non-cultivable bacteria and natural communities.Th2 cytokine bias induced by silver nanoparticles in peripheral blood mononuclear cells of common bottlenose dolphins (Tursiops truncatus)https://peerj.com/preprints/270492018-07-232018-07-23Wen-Ta LiLei-Ya WangHui-Wen ChangWei-Cheng YangChieh LoVictor Fei PangMeng-Hsien ChenChian-Ren Jeng
Background Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability. The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect animals at high trophic level, such as cetaceans and humans, via the food chain. Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in the modulation of immune system and can be classified into two types, Th1 and Th2. Th1/Th2 balance can be evaluated by the ratios of their polarizing cytokines (i.e., interferon [IFN]-γ/ Interleukin [IL]-4), and animals with imbalanced Th1/Th2 response may become more susceptible to certain kinds of infection. Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).
Methods Blood samples were collected from 6 captive common bottlenose dolphins (Tursiops truncatus). The cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses. The cytokines evaluated included IL-2, IL-4, IL-10, IL-12, interferon (IFN)-γ, and tumor necrosis factor (TNF)-ɑ. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each sample were determined and used to normalize the mRNA expression levels of target genes.
Results The ratio of late apoptotic/necrotic cells of cPBMCs significantly increased with or without concanavalin A (ConA) stimulation after 24 h of 10 μg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 μg/ml C-AgNP20 treatment. At 24 h of culture with 1 μg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased, with the exceptions of IL-4 and IL-10. The IFN-γ/IL-4 ratio was significantly decreased at 24 h of culture with 1 μg/ml C-AgNP20 treatment, and the IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 μg/ml C-AgNP20 treatment, respectively. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 μg/ml C-AgNP20 after 24 h of culture.
Discussion The present study demonstrated that the sublethal dose of C-AgNP20 (≤ 1 μg/ml) had an inhibitory effect on the cytokine mRNA expression levels of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased the mRNA expression level of TNF-α. Th2 cytokine bias is associated with enhanced immunity against parasites but decreased immunity to intracellular microorganisms. TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens. In summary, our data indicate that C-AgNP20 suppresses the cellular immune response and thereby increases the susceptibility of cetaceans to infection by intracellular microorganisms.
Background Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability. The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect animals at high trophic level, such as cetaceans and humans, via the food chain. Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in the modulation of immune system and can be classified into two types, Th1 and Th2. Th1/Th2 balance can be evaluated by the ratios of their polarizing cytokines (i.e., interferon [IFN]-γ/ Interleukin [IL]-4), and animals with imbalanced Th1/Th2 response may become more susceptible to certain kinds of infection. Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).Methods Blood samples were collected from 6 captive common bottlenose dolphins (Tursiops truncatus). The cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses. The cytokines evaluated included IL-2, IL-4, IL-10, IL-12, interferon (IFN)-γ, and tumor necrosis factor (TNF)-ɑ. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each sample were determined and used to normalize the mRNA expression levels of target genes.Results The ratio of late apoptotic/necrotic cells of cPBMCs significantly increased with or without concanavalin A (ConA) stimulation after 24 h of 10 μg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 μg/ml C-AgNP20 treatment. At 24 h of culture with 1 μg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased, with the exceptions of IL-4 and IL-10. The IFN-γ/IL-4 ratio was significantly decreased at 24 h of culture with 1 μg/ml C-AgNP20 treatment, and the IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 μg/ml C-AgNP20 treatment, respectively. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 μg/ml C-AgNP20 after 24 h of culture.Discussion The present study demonstrated that the sublethal dose of C-AgNP20 (≤ 1 μg/ml) had an inhibitory effect on the cytokine mRNA expression levels of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased the mRNA expression level of TNF-α. Th2 cytokine bias is associated with enhanced immunity against parasites but decreased immunity to intracellular microorganisms. TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens. In summary, our data indicate that C-AgNP20 suppresses the cellular immune response and thereby increases the susceptibility of cetaceans to infection by intracellular microorganisms.Analysis of the mixture toxicity burden in 17 rivers in north eastern Australia – implications for the Great Barrier Reef.https://peerj.com/preprints/270462018-07-202018-07-20Francis SpilsburyMichael St.J WarneThomas Backhaus
The Great Barrier Reef (GBR) is a protected ecosystem, listed as a UNESCO World Heritage site since 1981. It runs for approximately 3000km along the coastline in north-eastern Australia. A total of thirty-five major river basins discharge to the GBR and many transport large loads of pesticides, suspended sediment, nutrients from agricultural land. Over the past 6 years an extensive program has been conducted by the Queensland Government to monitor concentrations of 51 pesticides and their breakdown products in 17 rivers that discharge to the GBR. To explore the potential impact that the pesticides pose to the riverine environments and to the GBR we analysed the risk posed by the individual pesticides and their mixtures. Australia currently does not have water quality guidelines for 17 of the 38 pesticides detected. For those, we calculated ecotoxicity thresholds using a simplified version of the Australian methodology for determining water quality guideline values, based on species-sensitivity distributions. In all rivers, multiple pesticides were routinely detected at concentrations greater than their level of reporting. All rivers had at least one sample where the combined toxicity was greater than 1 toxic unit (TU), i.e. exposure situations where the total pesticide concentration exceeded acceptable levels. In a number of rivers more than 50% of samples had a combined toxicity greater than 1 TU. Average TU’s per river ranged from 13.47 to 0.10, with substantial fluctuations over the seasons but without clear trends between years. The patterns indicate that specific events such as severity of wet/dry seasons and cyclone events impact the combined toxicity found. We also found land use patterns affected the combined toxicity in the river ecosystems. In each of the rivers, 90% of the expected mixture toxicity was caused by only between 2 and 6 pesticides, although the individual pesticides that dominated the combined toxicity differed between rivers.
The Great Barrier Reef (GBR) is a protected ecosystem, listed as a UNESCO World Heritage site since 1981. It runs for approximately 3000km along the coastline in north-eastern Australia. A total of thirty-five major river basins discharge to the GBR and many transport large loads of pesticides, suspended sediment, nutrients from agricultural land. Over the past 6 years an extensive program has been conducted by the Queensland Government to monitor concentrations of 51 pesticides and their breakdown products in 17 rivers that discharge to the GBR. To explore the potential impact that the pesticides pose to the riverine environments and to the GBR we analysed the risk posed by the individual pesticides and their mixtures. Australia currently does not have water quality guidelines for 17 of the 38 pesticides detected. For those, we calculated ecotoxicity thresholds using a simplified version of the Australian methodology for determining water quality guideline values, based on species-sensitivity distributions. In all rivers, multiple pesticides were routinely detected at concentrations greater than their level of reporting. All rivers had at least one sample where the combined toxicity was greater than 1 toxic unit (TU), i.e. exposure situations where the total pesticide concentration exceeded acceptable levels. In a number of rivers more than 50% of samples had a combined toxicity greater than 1 TU. Average TU’s per river ranged from 13.47 to 0.10, with substantial fluctuations over the seasons but without clear trends between years. The patterns indicate that specific events such as severity of wet/dry seasons and cyclone events impact the combined toxicity found. We also found land use patterns affected the combined toxicity in the river ecosystems. In each of the rivers, 90% of the expected mixture toxicity was caused by only between 2 and 6 pesticides, although the individual pesticides that dominated the combined toxicity differed between rivers.Microplastics in the environment: Much ado about nothing? A debatehttps://peerj.com/preprints/265072018-07-122018-07-12Thomas BackhausMartin Wagner
This manuscript documents a debate between the two authors on the issue of microplastics in the environment. It was sparked by a recent viewpoint article published by G. A. Burton in Environmental Science and Technology (http://doi.org/10.1021/acs.est.7b05463) and started as a Twitter debate. To expand, we decided to continue our conversation publishing 1000-word texts on PeerJ and responding to each other in roughly two-week intervals.
Currently, the text contains the following:
1) An introduction, which sets the scene for the article
2) Martin's kick-off statement “Soul-searching on microplastics: Lost in translation, prioritization and communication?”, dated Feb. 27, 2018
3) Thomas' opening statement “A genuine research topic, but let’s avoid hyperboles”, dated March 18, 2018
4) Martin’s rebuttal “Moving forward: What are the risks of microplastics?”, dated April 18, 2018
5) Thomas’ rebuttal “We need to do a classical risk assessment, but we can’t stop there”, dated May 18, 2018
6) Final statement of both authors, dated July 12, 2018
This manuscript documents a debate between the two authors on the issue of microplastics in the environment. It was sparked by a recent viewpoint article published by G. A. Burton in Environmental Science and Technology (http://doi.org/10.1021/acs.est.7b05463) and started as a Twitter debate. To expand, we decided to continue our conversation publishing 1000-word texts on PeerJ and responding to each other in roughly two-week intervals.Currently, the text contains the following:1) An introduction, which sets the scene for the article2) Martin's kick-off statement “Soul-searching on microplastics: Lost in translation, prioritization and communication?”, dated Feb. 27, 20183) Thomas' opening statement “A genuine research topic, but let’s avoid hyperboles”, dated March 18, 20184) Martin’s rebuttal “Moving forward: What are the risks of microplastics?”, dated April 18, 20185) Thomas’ rebuttal “We need to do a classical risk assessment, but we can’t stop there”, dated May 18, 20186) Final statement of both authors, dated July 12, 2018Field evaluation of the potential for avian exposure to clothianidin following the planting of clothianidin-treated corn seedhttps://peerj.com/preprints/269862018-06-122018-06-12Sean McGeeMelissa Whitfield-AslundDaiana DucaNicole KopyshTereza DanLoren KnopperLarry Brewer
This objective of this study was to quantify consumption of clothianidin-treated corn seed by birds following standard planting practices. Post-planting seed counts on 21 fields in southwestern Ontario, Canada, demonstrated that a small proportion of total sown treated seeds remained on the soil surface immediately post-planting (i.e. mean 0.3 ±0.2% of the total sown seeds). Behavior monitoring of individual birds and 24-hr remote video surveillance were deployed to investigate how much of the treated seed remaining on the soil surface was consumed by birds. Spotting scopes were used to monitor the full duration of the field visits of 596 individual birds during morning hours for three consecutive days after planting on each of the 21 fields. Only two birds were observed consuming treated seeds (one seed each) and three birds consumed seeds for which the treatment status could not be visually confirmed. Similarly, in > 1,380 hours of continuous video monitoring of field locations with the highest likelihood of avian exposure (where multiple treated seeds remained clustered on the soil surface), no birds were observed eating treated seed. This study provides field verification on two factors that determine exposure: 1) standard sowing practices in Ontario are effective at burying treated seeds such that the count of seeds on the soil surface after planting is low, and 2) foraging birds monitored on these fields consumed very few of the clothianidin-treated corn seeds remaining on the soil surface after planting.
This objective of this study was to quantify consumption of clothianidin-treated corn seed by birds following standard planting practices. Post-planting seed counts on 21 fields in southwestern Ontario, Canada, demonstrated that a small proportion of total sown treated seeds remained on the soil surface immediately post-planting (i.e. mean 0.3 ±0.2% of the total sown seeds). Behavior monitoring of individual birds and 24-hr remote video surveillance were deployed to investigate how much of the treated seed remaining on the soil surface was consumed by birds. Spotting scopes were used to monitor the full duration of the field visits of 596 individual birds during morning hours for three consecutive days after planting on each of the 21 fields. Only two birds were observed consuming treated seeds (one seed each) and three birds consumed seeds for which the treatment status could not be visually confirmed. Similarly, in > 1,380 hours of continuous video monitoring of field locations with the highest likelihood of avian exposure (where multiple treated seeds remained clustered on the soil surface), no birds were observed eating treated seed. This study provides field verification on two factors that determine exposure: 1) standard sowing practices in Ontario are effective at burying treated seeds such that the count of seeds on the soil surface after planting is low, and 2) foraging birds monitored on these fields consumed very few of the clothianidin-treated corn seeds remaining on the soil surface after planting.