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- Gardeström, Johanna, 1975-
(författare)
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Coping with environmental stress : from the individual and population perspective
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural stress and disturbances are important factors affecting the structure and function of ecosystems. However the magnitude of stress has escalated due to anthropogenic activities. Environmental monitoring and toxicity assessments try to protect ecosystems from unwanted human alterations. The aim of this Doctoral thesis was to increase the understanding of the complex effects that environmental stress has on individuals and invertebrate populations. The low saline environment in the Baltic Sea is perceived as stressful for most organisms living there. In Paper I, it was found that Baltic blue mussels living in the less saline northern Baltic Proper (~5 psu) had lower basal metabolism and were more susceptible to toxic exposure than the mussels in the south (~7 psu). There was no genetic differentiation between the mussels from the northern and southern areas while there were genetic differences between mussels from sites within the respective areas (Paper III), indicating that there is not a simple relationship between the health of the mussels and genetic diversity in the microsatellite loci studied. In Paper IV it was found that the heat tolerance of the intertidal dogwhelk Nucella lapillus is oxygen dependent. Increased oxygen levels resulted in higher survival rate. Protein expression profiles also became more similar to those of the controls, compared to the whelks exposed to high temperature and normal oxygen levels. In Paper V and VI it was found that exposure to a single toxicant for more than one generation decreased the genetic diversity in exposed copepod populations even though abundances remained unaltered. In Paper VI, exposure to naturally contaminated sediments, which contained of a mixture of toxicants, did not decrease genetic diversity. However the genetic divergence (FST) within the treatments was very high, probably due to small effective population sizes in the replicates. Likewise in Paper III, the very low blue mussel abundance in the north together with the stressful environment suggests a small effective population in the northern Baltic Proper. In conclusion, my studies show that, measuring effects on several levels, including both functional and structural endpoints will both increase the sensitivity of the tests and increase their ecological relevance.
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| 2. |
- Gardeström, Johanna, et al.
(författare)
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The effect of thermal stress on protein composition in dogwhelks (Nucella lapillus) under normoxic and hyperoxic conditions
- 2007
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 148:4, s. 869-875
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Tidskriftsartikel (refereegranskat)abstract
- In this laboratory study, dogwhelks (Nucella lapillus) were collected from the intertidal zone and exposed to 16 °C (ambient), 26.5 °C and 30 °C under normal and hyperoxic conditions respectively. It was shown that there was no thermally induced mortality at 26.5 °C, but that the mortality rate was 40–50% in 30 °C. This mortality rate was reduced to 10% if extra oxygen was provided, indicating that oxygen supply was setting the limit for whole organism thermal tolerance. Tissue samples were then analysed for protein features using two-dimensional gel electrophoresis, and both up and down regulation of proteins were visualised by silver staining and crosswise comparisons of gels from control vs. treated animals. The results clearly show that the protein profiles from dogwhelks exposed to increased water temperatures differ from those of the control, but that increased oxygen availability alleviates these differences thus increasing the similarity between heat-shocked and control animal protein pattern. This implies a more stable protein metabolism and might explain the increased survival of heat-shocked individuals when extra oxygen is supplied.
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| 3. |
- Lilja, Carl, et al.
(författare)
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Regional differences in mRNA responses in blue mussels within the Baltic proper
- 2008
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Ingår i: Comparative Biochemistry and Physiology - Part C. - : Elsevier BV. - 1532-0456 .- 1878-1659. ; 148:2, s. 101-106
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Tidskriftsartikel (refereegranskat)abstract
- Mussels (Mytilus sp.) from two regions along the permanent salinity gradient within the Baltic proper were exposed to copper (35 ppb) or petrol (0.3 mL/L) for 10 days and analyzed for mRNA expressions in gill tissue. Expression of mRNAs for the heat shock proteins HSP70 and HSP90 was significantly induced by copper, but not by petrol. For the metallothioneins MT10 and MT20, regional differences in mRNA expressions could be seen. In mussels from the northern Baltic proper, MT20 expression increased 2.8 and 3.4 times, after exposure to copper and petrol, respectively. In contrast, no change could be seen in MT20 expression for mussels from the southern Baltic proper. MT10 showed a peculiar expression not previously described. For some mussels, no expression at all was detected, some showed a weak expression and for some individuals a strong expression could be seen. For the mussels from the southern Baltic proper, the number of individuals with a strong expression of MT10 increased from 1 out of 18 (control), to 7 and 8, after exposure to copper and petrol, respectively. The results clearly show that responses vary between different regions within the Baltic proper, which emphasises the importance to study interactions between contaminants, populations and regions.
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| 4. |
- Olsson, Björne
(författare)
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Protein Expression in Baltic Sea Blue Mussels Exposed to Natural and Anthropogenic Stress : The use of stress inducible proteins in ecotoxicological studies
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis is the early detection of stress in the environment. It has been proposed that studies on the cellular level would detect stress reactions earlier in time compared to common physiological methods. In a series of experiments we investigated how different stress factors, both natural and introduced by man, affect levels of stress proteins. One- and two-dimensional gels were used to determine individual proteins and families of proteins. The two-dimensional gels were also used in a proteomic approach, were the presence and absence of proteins after treatment was observed, and the protein expression signatures (PES) were identified. Baltic Mytilus edulis was used in all experiments and it is evident that earlier observed differences in physiological rates and pollution sensitivity, compared to marine mussels, is also manifested as lower concentrations of stress proteins after exposure to copper and cadmium. When the Baltic mussels were allowed to acclimate for one month the difference decreased, suggesting an environmentally induced difference (paper I). Pre-exposure to heat before exposure to either a second heat-shock or cadmium was found to enhance the levels of HSP70 and thus tolerance, significantly (paper II). Exposure to a mixture of stress factors (PCB, copper and lowered salinity) revealed synergistic, additive and antagonistic effects in induction of 6 different stress proteins. When analyzing a large number of proteins it was shown that it is possible to identify PES with this technique, and we hypothesize that it could be possible to separate responses to mixtures of stress factors (Papers III and IV). Different techniques were also applied to analyze the protein expression pattern when mussels were exposed to PAH- and PCB-fractions extracted from Baltic Sea sediments. In this experiment the protein assays were accompanied by physiological measurements. All methods indicated stressed conditions, but the variation between individual mussels within treatments was smaller in terms of protein response than for physiological parameters (paper V). It is concluded that measuring the induction of stress proteins is a reliable way to detect stressful conditions. Proteins visualized on a one dimensional gel give a “gross” picture of an organism’s condition. The major challenge is to identify the origin and severity of the elucidated stress response. Further mapping of two-dimensional gels suggested that protein patterns are specific to type and level of stress. A most important future step is to establish links between sub-cellular protein response to well known physiological effects. This should include long term experiments where altered protein expression signatures are linked to life history characteristics like survival, growth and reproductive success.
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| 5. |
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| 6. |
- Prevodnik, Andreas, et al.
(författare)
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Oxidative stress in response to xenobiotics in the blue mussel Mytilus edulis L. : evidence for variation along a natural
- 2007
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 82:1, s. 63-71
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Tidskriftsartikel (refereegranskat)abstract
- Blue mussels (Mytilus edulis L.) collected at three sampling sites in each of three geographical regions (South, Middle, North) along the permanent longitudinal South-North salinity gradient of the Baltic Sea, were exposed for 10 days to copper (35 ppb) or 95 octane petrol (0.3%0). During the experiment, they were maintained at the respective sampling site salinity. Scope for growth (SFG) was determined, and biochemical stress markers (protein carbonyl groups, disulfide bond formation, and glutathione transferase (GST), and catalase (CAT) activities) were investigated in gill tissue upon termination of the experiment. Treatment and regional effects for SFG and protein carbonyl groups were all significant for petrol. The largest increase in protein carbonyl groups was observed in the North. Mussels from the southern, more saline (similar to 7%) region had the highest SFG, and displayed the largest SFG decrease in response to treatment, indicating that they had the most energy available for allocation to stress response. They also displayed the least increase in the level of protein carbonyl groups. Mussels from the Northern, less saline (similar to 5%) region had the highest degree of protein carbonyl groups in response to both treatments, and lowest average SFG. Silver stained diagonal gels for samples from one sampling site in South and North, respectively, demonstrated differences in disulfide bond profiles for both stress treatments. There was also a regional difference in the number of protein disulfides observed on diagonal gels. The most diverse protein disulfide response was found in South. No treatment related effects on GST and CAT activities were observed. We suggest that both SFG and protein carbonyl groups show that geographical difference in stress susceptibility, previously established between the North and the Baltic Seas, also apply on a regional scale within the Baltic Sea, along the salinity gradient.
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| 7. |
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| 8. |
- Prevodnik, Andreas, 1974-
(författare)
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The use of protein biomarkers in ecotoxicology : Studies of oxidative and genotoxic stress in the blue mussel (Mytilus edulis)
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many environmental pollutants, heavy metals and polyaromatic hydrocarbons (PAHs) among them, are toxic by oxidative stress. Oxidative stress may be defined as a state in an organism when its inherent capacity to handle oxyradicals is surpassed, and it may result in peroxidation of lipids, and damage to proteins and DNA. Thus, genotoxic stress may follow oxidative stress.Little is known about the effects of genotoxic stress in invertebrates, although the occurrence of tumors has been known for quite some time, in bivalve mollusks at least since the 1960s. Less dramatic manifestations of genotoxic stress may include impaired enzyme functions, altered protein turnover, with possible effects on physiological processes. Keys to a better understanding of genotoxic stress are the proteins involved in the regulation of the cell-cycle and DNA repair. Virtually nothing is known about these proteins in mussels. The work presented in the papers I, II, and IV aimed to give a first insight into how the blue mussel responds to genotoxic stress following exposure to the polyaromatic hydrocarbon (PAH) benzo[a]pyrene (B[a]P), PAHs in petrochemical pollution, copper (Cu) or cadmium (Cd), all substances known to enhance formation of oxyradicals. PAHs may also be genotoxic by formation of DNA adducts. The cell-cycle and DNA repair proteins studied were the proliferating cell nuclear antigen (PCNA) and the retinoblastoma protein 110 (Rb110). The first is involved in DNA repair and cell proliferation; the second at the G1 checkpoint of the cell-cycle. We showed that the PCNA is a potential marker of genotoxic response (DNA repair, and/or cell proliferation) to PAHs (papers I and IV) and cadmium (paper II). Furthermore, cadmium may possibly elicit a cell-cycle stop mediated by the Rb110 (the paper II). Based on these cell-cycle and DNA repair proteins, the genotoxic responses in blue mussels seem to be similar to that in vertebrates.Markers of general stress or oxidative stress were used in all studies. The applicability of the general stress marker heat shock proteins (HSP70 and HSP60) (papers I and IV), the polyglycoprotein (P-gp) (paper I), a marker of exposure to planar organic compounds, and markers of oxidative stress, such as the antioxidant defense enzyme copper/zinc-superoxide dismutase (Cu/Zn-SOD) (paper II), and the oxidative protein modifications protein carbonyls and disulfides (papers III and IV) were tested in various situations. In accordance with results by others, my studies have shown that HSPs, which formerly were considered as universal stress markers, are not always applicable, as their expression is affected by factors that are difficult to control (papers I). I found that the P-gp can be used as a marker of B[a]P exposure in Baltic Sea blue mussels (paper I). In paper II, I reported that the Cu/Zn-SOD was up-regulated in response to Cd exposure, a clear indication of oxidative stress that was also manifested as a response in the studied cell-cycle and DNA repair proteins. Protein carbonyls were successfully used in the papers III and IV to indicate oxidative stress. In paper III, I also investigated the potential of diagonal gels as a tool for identification of protein disulfides in protein expression signatures (PESs). The diagonal gels hold a good potential for identification of novel and prime targets of oxidative stress.My work was performed as short-term laboratory studies, in vivo, in blue mussels from the Baltic Sea, and as a one year long field experiment with Icelandic blue mussels in a tidal system. The idea was to use blue mussels that were already physiologically challenged (by osmotic stress, or alternating aerobic and anaerobic metabolism), to see how they responded to additional stress in the form of toxicants capable of inducing oxidative and genotoxic stress. Most of the work on biochemical endpoints in blue mussels published so far was done on blue mussels from fully marine environments, and without consideration to the effect of tide.
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