27 research outputs found
The Stressful Effects of Microplastics Associated With Chromium (VI) on the Microbiota of Daphnia Magna
Contamination by microplastics (particles < 1 mm) is a growing and alarming environmental problem in freshwater systems. Evidence suggests that industrial effluents could be one of the critical point sources of microplastics and other pollutants, and their interaction can cause organismal stress and affect host and environmental microbial communities. We tested the individual and combined effects of microplastics and other pollutants on host survival and host associated (commensal) bacterial diversity. We exposed Daphnia magna to 1 mu m microplastic beads with a concentration of approximately 1820 particles/ml and chromium (VI) simultaneously with treatments of 2 and 5 ppm for 72 h. DNA extraction was done to amplify and sequence the ribosomal Bacterial 16S from both the water and the Daphnia. Daphnia experienced low mortality in treatments microplastics (13.3%) and 2 ppm chromium VI (30%) individually. However, the combination of microplastics and 2 ppm chromium (VI) increased the mortality to 74.4%. In the treatments with 5 ppm of chromium (VI) mortality rose to 100% after 30 h of exposure. Microbial diversity changed in response to microplastics, chromium (VI), and both combined exposure. Microplastics and toxic metals can cause dysbiosis of freshwater environmental microbiota, whole host microbiota, and host survival. This work stresses the importance to assess how pollutants' individual and joint effects could affect organisms including their microbiome
Persistent activation of DNA damage signaling in response to complex mixtures of PAHs in air particulate matter
Complex mixtures of polycyclic aromatic hydrocarbons (PAHs) are present in air particulate
matter (PM) and have been associated with many adverse human health effects including
cancer and respiratory disease. However, due to their complexity, the risk of exposure to
mixtures is difficult to estimate. In the present study the effects of binary mixtures of
benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) and complex mixtures of PAHs in urban
air PM extracts on DNA damage signaling was investigated. Applying a statistical model to
the data we observed a more than additive response for binary mixtures of BP and DBP on
activation of DNA damage signaling. Persistent activation of checkpoint kinase 1 (Chk1) was
observed at significantly lower concentrations of air PM extracts than BP alone. Activation of
DNA damage signaling was also more persistent in air PM fractions containing PAHs with
more than four aromatic rings suggesting larger PAHs contribute a greater risk to human
health. Altogether our data suggests that human health risk assessment based on additivity
such as toxicity equivalency factor scales may significantly underestimate the risk of
exposure to complex mixtures of PAHs. The data confirms our previous findings with PAHcontaminated
soil (Niziolek-Kierecka et al. 2012) and suggests a possible role for Chk1
Ser317 phosphorylation as a biological marker for future analyses of complex mixtures of
PAHsFormasCancer- och AllergifondenStockholm UniversityEU/FP7 Marie Curie IRG fellowshipAccepte
Benzo[a]pyrene-specific online high-performance liquid chromatography fractionation of air particulate extracts : a tool for evaluating biological interactions.
Benzo[a]pyrene (B[a]P) is a known human carcinogen and is commonly used as a
surrogate for assessing the carcinogenic risk posed by complex mixtures of
polycyclic aromatic hydrocarbons (PAHs) present in air particulate matter (PM).
However, studies have shown that using B[a]P as a surrogate may underestimate the
carcinogenic potential of PAH mixtures, as the risk assessment approach does not
consider interaction effects. Thus, toxicological studies using B[a]P to assess
its carcinogenic potential in environmentally derived complex mixtures, as
opposed to single compound experiments, could improve risk assessment. The
intention of the present study was to develop an online HPLC fractionation system
for the selective removal of B[a]P from air PM extracts. Two serial pyrenylethyl
(PYE) columns enabled selective separation of B[a]P from its isomers and other
PAHs as well as a short fractionation cycle of 30min. One run consisted of three
collection steps: the first fraction contained PAHs eluting earlier than B[a]P,
the second contained B[a]P and the last contained later-eluting PAHs. The
selectivity and recovery of the system was investigated using extracts of
Stockholm air PM samples. The overall recovery for all PAHs was approximately
80%, and the system proved to be selective, as it removed 94% of B[a]P and less
than 3% of benzo[b]fluoranthene from the complex PAH mixture. Exposing human
cells to blanks generated by the fractionation system did not induce cytotoxicity
or DNA damage signalling. In conclusion, the online HPLC system was selective for
B[a]P fractionation whilst minimising run-to-run variation and allowing repeated
fractionations for larger samples due to its relatively short run time.FormasAccepte
Nanomolar levels of PAHs in extracts from urban air induce MAPK signaling in HepG2 cells.
Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that
occur naturally in complex mixtures. Many of the adverse health effects of PAHs
including cancer are linked to the activation of intracellular stress response
signaling. This study has investigated intracellular MAPK signaling in response
to PAHs in extracts from urban air collected in Stockholm, Sweden and Limeira,
Brazil, in comparison to BP in HepG2 cells. Nanomolar concentrations of PAHs in
the extracts induced activation of MEK4 signaling with down-stream increased gene
expression of several important stress response mediators. Involvement of the
MEK4/JNK pathway was confirmed using siRNA and an inhibitor of JNK signaling
resulting in significantly reduced MAPK signaling transactivated by the AP-1
transcription factors ATF2 and c-Jun. ATF2 was also identified as a sensitive
stress responsive protein with activation observed at extract concentrations
equivalent to 0.1 nM BP. We show that exposure to low levels of environmental PAH
mixtures more strongly activates these signaling pathways compared to BP alone
suggesting effects due to interactions. Taken together, this is the first study
showing the involvement of MEK4/JNK/AP-1 pathway in regulating the intracellular
stress response after exposure to nanomolar levels of PAHs in environmentalFormasAccepte
Wood smoke particles from different combustion phases induce similar pro-inflammatory effects in a co-culture of monocyte and pneumocyte cell lines
Background
Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles’ physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures.
Results
WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved.
Conclusion
The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs
Sensitivity of Salmonella YG5161 for detecting PAH-associated mutagenicity in air particulate matter.
The Salmonella/microsome assay is the most used assay for the evaluation of air
particulate matter (PM) mutagenicity and a positive correlation between strain
TA98 responses and benzo[a]pyrene (B[a]P) levels in PM has been found. However,
it seems that the major causes of PM mutagenicity in this assay are the nitro and
oxy-PAHs. Salmonella YG5161, a 30-times more responsive strain to B[a]P has been
developed. To verify if YG5161 strain was sufficiently sensitive to detect
mutagenicity associated with B[a]P mutagenicity, PM samples were collected in
Brazil and Sweden, extracted with toluene and tested in the Salmonella/microsome
microsuspension assay. PAHs and B[a]P were determined and the extracts were
tested with YG5161 and its parental strain TA1538. The extracts were also tested
with YG1041 and its parental strain TA98. For sensitivity comparisons, we tested
B[a]P and 1-nitropyrene (1-NP) using the same conditions. The minimal effective
dose of B[a]P was 155 ng/plate for TA1538 and 7 ng/plate for YG5161. Although the
maximum tested dose, 10 m(3) /plate containing 9 ng of B[a]P in the case of
Brazilian sample, was sufficient to elicit a response in YG5161, mutagenicity was
detected at a dose as low as 1 m(3) /plate (0.9 ng). This is probably caused by
nitro-compounds that have been shown to be even more potent than B[a]P for
YG5161. It seems that the mutagenicity of B[a]P present in PM is not detectable
even with the use of YG5161 unless more efficient separation to remove the
nitro-compounds from the PAH extract is performed.FormasAccepte
Detection of benz[j]aceanthrylene in urban air and evaluation of its genotoxic potential.
Benz[j]aceanthrylene (B[j]A) is a cyclopenta-fused polycyclic aromatic
hydrocarbon with strong mutagenic and carcinogenic effects. We have identified
B[j]A in air particulate matter (PM) in samples collected in Stockholm, Sweden
and in Limeira, Brazil using LC-GC/MS analysis. Determined concentrations ranged
between 1.57 and 12.7 and 19.6-30.2 pg/m(3) in Stockholm and Limeira,
respectively, which was 11-30 times less than benzo[a]pyrene (B[a]P)
concentrations. Activation of the DNA damage response was evaluated after
exposure to B[j]A in HepG2 cells in comparison to B[a]P. We found that
significantly lower concentrations of B[j]A were needed for an effect on cell
viability compared to B[a]P, and equimolar exposure resulted in significant more
DNA damage with B[j]A. Additionally, levels of gammaH2AX, pChk1, p53, pp53, and
p21 proteins were higher in response to B[j]A than B[a]P. On the basis of dose
response induction of pChk1 and gammaH2AX, B[j]A potency was 12.5- and 33.3-fold
higher than B[a]P, respectively. Although B[j]A levels in air were low, including
B[j]A in the estimation of excess lifetime cancer risk increased the risk up to
2-fold depending on which potency factor for B[j]A was applied. Together, our
results show that B[j]A could be an important contributor to the cancer risk of
air PM.FormasAccepte
Relatório de estágio profissional
O presente Relatório foi realizado no âmbito do Estágio Profissional I e II. Trata-se de um trabalho elaborado com base na observação de aulas e na experimentação didática; os materiais obtidos (como, por exemplo, horários, dados sobre as turmas, fichas, etc.) foram submetidos a uma análise documental
Photocatalytic Decomposition of Formic Acid on Mo2C-Containing Catalyst
Soluble components in the peripheral blood from experimental exposure of 14 healthy subjects to filtered air and wood smoke. Samples were collected before (pre), at 24 h and 44 h after exposure, to air and wood smoke. Data are given as medians with interquartile range. (DOCX 62 kb
The Economic Impact of Autonomous Vehicles in the Logistics Industry
In an ever-changing industry where competition between actors is growing, technical improvements and investments can be a way to outperform competitors and gain competitiveadvantages. In a relatively under-developed industry, technological developments may leadto major improvements and change the layout of the whole business. Purpose – The main purpose of this thesis is to investigate potential cost reductions obtained by autonomous vehicles within the Swedish logistics industry. Studying opportunities for companies tostrengthen their competitive advantage can create new markets, chances or ensure a strongmarket position. To investigate said opportunities, the following research questions werestated: What is the actual cost of implementing an autonomous vehicle? Which costs will be affected by an implementation of autonomous vehicles? How do these costs impact the Swedish logistics market seen from a cost perspective? Method – The data necessary to answer the questions was collected from document studies, literature studies and interviews. These were carried out simultaneously in an iterativeprocess. Moreover, a pragmatic philosophy was undertaken, together with an abductive approach. The data was compared with existing theory by pattern matching and analysed withthematic approach, in order to ensure the level of trustworthiness. Findings/Implications – The findings of this thesis is that autonomous vehicles willheavily impact the logistics industry. By gradually implementing autonomous vehicles, theSwedish logistics sector can save upwards of 13,4 billion SEK between 2020 and 2030.This shift towards autonomous vehicles will move jobs from the long haul sector to urbanlogistics and telecommunications. Additionally, the society will see great benefits as 90% ofall traffic accidents will not happen when all vehicles are autonomous. It is clear that theSwedish logistics industry will benefit from an implementation of autonomous vehicles.Simultaneously it will also be beneficial for the society and the Swedish welfare. Limitations – The major limitation of this thesis is the time horizon. Because of being future oriented, much data was based on external estimations that might change over time.Moreover, only costs directly connected to transportations has been investigated, leavingroom for further studies related to indirect costs, as well as the organizational impacts onfuture supply chains