| 1. |
- Björkman, Camilla, et al.
(author)
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Cryptosporidium infections in suckler herd beef calves
- 2015
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In: Parasitology. - 0031-1820 .- 1469-8161. ; 142, s. 1108-1114
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Journal article (peer-reviewed)abstract
- A study was carried out to investigate how common Cryptosporidium infections are in beef calves in Swedish suckler herds and to explore which species and subtypes that occur. We further aimed at identifying factors associated with shedding of Cryptosporidium oocysts in this type of calf management. The study was conducted in two regions in Sweden and included 30 herds. Faecal samples were collected from calves younger than 3 months. A brief clinical examination was done and a questionnaire was used to collect data on management routines. Faeces were cleaned and concentrated and oocysts identified by epifuorescence microscopy. Cryptosporidium positive samples were analyzed at the 18S rRNA and GP60 genes to determine species and Cryptosporidium parvum subtype, respectively. Logistic regression was used to identify factors associated with infection. Oocysts were detected in 122 (36·7%) calves from 29 (97%) herds, at 400 to 2·4 × 107 OPG. The youngest positive calves were only 1 and 2 days old. There was no association between age and Cryptosporidium infection. Cryptosporidium bovis, C. ryanae, C. parvum and C. ubiquitum were identified, with C. bovis being the major species. Two C. parvum subtypes, IIaA16G1R1 and IIdA27G1 were identified. Routines for cleaning calf pens and number of cows in calving pens were associated with infection.
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| 2. |
- Oweson, Carolina, et al.
(author)
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A comparative study on the influence of manganese on the bactericidal response of marine invertebrates
- 2009
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In: Fish and Shellfish Immunology. - 1050-4648 .- 1095-9947. ; 27:3, s. 500-507
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Journal article (peer-reviewed)abstract
- Manganese, Mn, is a naturally abundant metal in marine sediments. During hypoxic conditions the metal converts into a bioavailable state and can reach levels that have been shown immunotoxic to the crustacean Nephrops norvegicus. For this species it has previously been shown that exposure to 15 mg L(-1) of Mn decreased the number of circulating haemocytes while it for the echinoderm Asterias rubens increased the number of coelomocytes. Here, we compared if five days of exposure to the same concentration of Mn affects the bactericidal capacity of these two species and the mollusc Mytilus edulis when inoculated with the bacterium Vibrio parahaemolyticus. Viable counts of the bacteria were investigated at a time-course post-injection in the blood and the digestive glands of Mn-exposed and un-exposed (controls) animals. Accumulation of Mn was also analyzed in these tissues. When exposed to Mn the haemocyte numbers were significantly reduced in M. edulis and it was shown that the bactericidal capacity was impaired in the mussels as well as in N. norvegicus. This was most obvious in the digestive glands. These two species also showed the highest accumulation of the metal. In A. rubens the bactericidal capacity was not affected and the metal concentration was similar to the exposure concentration. After a recovery period of three days the concentration of Mn was significantly reduced in all three species. However, in M. edulis and N. norvegicus it was still double that of A. rubens which could explain the remaining bactericidal suppression observed in N. norvegicus. This study pointed out that exposure to such Mn-levels that are realistic to find in nature could have effects on the whole organism level, in terms of susceptibility to infections. The effect seemed associated to the accumulated concentration of Mn which differed on species level.
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| 3. |
- Oweson, Carolina, et al.
(author)
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A comparative study on the influence of manganese on the bactericidal response of marine invertebrates
- 2009
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In: Fish and Shellfish Immunology. - : Academic Press Inc.. - 1050-4648 .- 1095-9947. ; 27:3, s. 500-507
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Journal article (peer-reviewed)abstract
- Manganese, Mn, is a naturally abundant metal in marine sediments. During hypoxic conditions the metal converts into a bioavailable state and can reach levels that have been shown immunotoxic to the crustacean Nephrops norvegicus. For this species it has previously been shown that exposure to 15 mg L(-1) of Mn decreased the number of circulating haemocytes while it for the echinoderm Asterias rubens increased the number of coelomocytes. Here, we compared if five days of exposure to the same concentration of Mn affects the bactericidal capacity of these two species and the mollusc Mytilus edulis when inoculated with the bacterium Vibrio parahaemolyticus. Viable counts of the bacteria were investigated at a time-course post-injection in the blood and the digestive glands of Mn-exposed and un-exposed (controls) animals. Accumulation of Mn was also analyzed in these tissues. When exposed to Mn the haemocyte numbers were significantly reduced in M. edulis and it was shown that the bactericidal capacity was impairedin the mussels as well as in N. norvegicus. This was most obvious in the digestive glands. These two species also showed the highest accumulation of the metal. In A. rubens the bactericidal capacity was not affected and the metal concentration was similar to the exposure concentration. After a recovery period of three days the concentration of Mn was significantly reduced in all three species. However, in M. edulis and N. norvegicus it was still double that of A. rubens which could explain the remaining bactericidal suppression observed in N. norvegicus. This study pointed out that exposure to such Mn-levels that are realistic to find in nature could have effects on the whole organism level, in terms of susceptibility to infections. The effect seemed associated to the accumulated concentration of Mn which differed on species level.
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| 4. |
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| 5. |
- Oweson, Carolina A. M., 1976, et al.
(author)
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Effects of manganese and hypoxia on coelomocyte renewal in the echinoderm, Asterias rubens (L.)
- 2010
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 100:1, s. 84-90
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Journal article (peer-reviewed)abstract
- Manganese (Mn) is a naturally abundant metal and particularly so in soft-bottom oceanic sediments where it generally occurs bound in a four-valent colloidal state as MnO2. When hypoxic conditions occur in bottom waters, the metal reduces to the bioavailable ion Mn2+ and can reach concentrations known to have immunotoxic effects in the crustacean Nephrops norvegicus, reducing numbers of circulating haemocytes as a consequence. However, we have previously shown that Mn seems to have a contrasting effect on the echinoderm Asterias rubens in which it triggers the proliferation of haematopoietic cells and increases coelomocyte numbers. Since elevated Mn levels mostly co-occur with hypoxia in nature, here we investigated whether hypoxia has a negative effect on haematopoiesis. Proliferation and differentiation of coelomocytes and cells in the coelomic epithelium of A. rubens were compared after 3 days of exposure to realistic levels of Mn, hypoxia or a combination of these two parameters. We can confirm that Mn elevated numbers of coelomocytes and increased proliferation of epithelial cells, but hypoxia did not affect these levels. However, hypoxia did affect differentiation of these cells as judged by investigating the expression of a Runt domain transcription factor, which was also cloned and sequenced. Through comparative quantification using a real time PCR technique, we found that exposure to hypoxia had a clearly stimulating effect on mRNA expression of Runt gene in both coelomocytes and epithelial cells. These results indicate that during hypoxic conditions the composition of coelomocyte sub-populations changed. (c) 2010 Elsevier B.V. All rights reserved.
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| 6. |
- Oweson, Carolina A. M., 1976
(author)
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Immunotoxicology in Marine Invertebrates - Effects of Manganese on Immune Response
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Manganese, Mn, is an abundant element in nature, particularly in soft bottom sediments of the oceans and in bedrock. The metal is predominantly bound to the sediment in the colloid state, MnO2. Eutrophication caused by the high nutrient load in coastal waters together with over-fishing cause cascade effects in the ecosystem increasing the algal blooms and enhancement of hypoxic condition over large bottom areas. During hypoxic events MnO2 is reduced and released into the bottom water as bioavailable ions, Mn2+. Mn is essential for several metabolic and enzymatic processes and is necessary for both animals and plants. Elevated levels though, are toxic and severe effects on the nervous system have been known for long. In addition, previous studies have shown an impaired immune system of the bottom living lobster, Nephrops norvegicus, when exposed to concentrations that are realistic to find in nature. In this study I aimed to investigate if immunotoxic effects of manganese are general also for other marine invertebrates. It is widely accepted that invertebrates do not have a documented so called adaptive immune response. They lack the genes, proteins and cells for the highly specific recognition and the long-term memory as found in vertebrates. Invertebrates primarily rely on the innate immune system to effectively combat a wide array of microbial pathogens. The innate immune system comprises of a first line of defence systems such as coagulation and melanization reactions, often followed by cellular reactions such as phagocytosis, encapsulation and production of antimicrobial substances. Many innate immune reactions are highly evolutionary conserved and are found throughout the whole animal kingdom. In aquatic invertebrates the open coelom or semi-open haemal circulatory system continuously expose them to potential pathogens and their immune response has proved to be exceptionally efficient in pathogen elimination as witnesses by the invertebrates’ evolutionary success. In this thesis species from three different phyla within the Bilaterians were investigated; the Norway lobster, Nephrops norvegicus (Crustacea), the blue mussel Mytilus edulis (Mollusca) and the common sea star, Asterias rubens (Echinodermata), differing in preferred habitats, feeding behaviour and somewhat in their strategies of immune defence. Studies were made on molecular, cellular and organism levels. On molecular and cellular levels we investigated the effects of manganese on the renewal of haemocytes (proliferation and differentiation of new cells), manganese effects on viability of haemocytes and the stress responses measured in both haemocytes and haematopoietic tissue. On the whole organism we investigated the effect of manganese on the ability for the animals to clear their cavity form injected bacteria. The results of this thesis show that Mn in concentrations found in bottom waters affects the immune system of marine invertebrates differently. In N. norvegicus the metal severely suppresses the number of circulating haemocytes by inducing apoptosis, programmed cell death. The impaired immunity made them more susceptible to infections, which was also found in M. edulis. In A. rubens the same Mn concentration seemed to have a stimulating effect (hormesis) on the haematopoiesis which increased the number of circulating haemocytes. Although manganese was shown stressful to the haemocytes and affected their ability to phagocyte, the increased number of haemocytes compensates these impairments. There was seemingly a negative correlation between the accumulation of the metal in the tissues of the animals and their ability to eliminate bacteria. Although Mn does not cause chronic effects on immunity, the expanding areas with bioavailable Mn might have an impact on species composition since some invertebrates become more susceptible to infections.
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| 7. |
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| 8. |
- Oweson, Carolina A. M., 1976, et al.
(author)
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Manganese induced apoptosis in haematopoietic cells of Nephrops norvegicus (L.)
- 2006
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X. ; 77:3, s. 322-328
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Journal article (peer-reviewed)abstract
- Manganese (Mn) is highly abundant as MnO2 in marine sediments. During hypoxia in bottom waters, the reduced bioavailable fraction of manganese, Mn2+, increases. Thereby, Norway lobster, Nephrops norvegicus, can experience concentrations up to 1000 times normoxic levels. A previous study has shown that exposure to a realistic concentration of 20 mg l(-1) of Mn for 10 days reduced the number of circulating haemocytes in N. norvegicus significantly. Here we aimed to investigate if apoptosis contributes to the Mn-induced haemocytopenia, with the overall hypothesis that Mn induces apoptosis in a time and concentration dependent manner. N. norvegicus were exposed to Mn (0, 5, 10 and 20 mg l(-1)) for 5 and 10 days. After 5 days of exposure the total haemocyte counts were not affected. However, after 10 days there was a gradual decrease in cell numbers, reaching a reduction by 44% when the animals were exposed to 20 mg Mn l(-1). Apoptosis in cells, released from the haematopoietic tissue, was investigated by using TUNEL assay, which detects specific DNA strand breaks. The fraction of apoptotic cells gradually increased from 2.5% in un-exposed lobsters to 15% in those exposed to 20 mg l(-1) but there was no difference related to the exposure time. A gradual increase of apoptosis was further confirmed by electrophoretic DNA-ladder formation, however to a lower extent in lobsters exposed during 5 days. Cell viability, determined by metabolic activity and cell membrane integrity, was not reduced, indicating that apoptosis rather than necrosis caused reduced number of haemocytes. It was concluded that apoptosis seemed to increase already after 5 days of 5 mg l(-1) of Mn-exposure, although exposure for 10 days was required before it was reflected in the haemocyte numbers. Reduced numbers of haemocytes may increase the prevalence for infections in N. norvegicus in their natural habitat. (c) 2006 Elsevier B.V. All rights reserved.
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| 9. |
- Oweson, Carolina A M, et al.
(author)
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Manganese induced apoptosisin haematopoietic cells of the lobster, Nephrops norvegicus (L)
- 2006
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In: Aquatic Toxicology. - 0166-445X. ; 77, s. 322-328
-
Journal article (peer-reviewed)abstract
- Manganese (Mn) is highly abundant as MnO2 in marine sediments. During hypoxia in bottom waters, the reduced bioavailable fraction ofmanganese, Mn2+, increases. Thereby, Norway lobster, Nephrops norvegicus, can experience concentrations up to 1000 times normoxic levels. A previous study has shown that exposure to a realistic concentration of 20 mg l−1 of Mn for 10 days reduced the number of circulating haemocytes in N. norvegicus significantly. Here we aimed to investigate if apoptosis contributes to the Mn-induced haemocytopenia, with the overall hypothesis that Mn induces apoptosis in a time and concentration dependent manner. N. norvegicus were exposed to Mn (0, 5, 10 and 20 mg l−1) for 5 and 10 days. After 5 days of exposure the total haemocyte counts were not affected. However, after 10 days there was a gradual decrease in cell numbers, reaching a reduction by 44% when the animals were exposed to 20 mg Mn l−1. Apoptosis in cells, released from the haematopoietic tissue, was investigated by using TUNEL assay, which detects specific DNA strand breaks. The fraction of apoptotic cells gradually increased from 2.5% in unexposed lobsters to 15% in those exposed to 20 mg l−1 but there was no difference related to the exposure time. A gradual increase of apoptosis was further confirmed by electrophoretic DNA-ladder formation, however to a lower extent in lobsters exposed during 5 days. Cell viability, determined by metabolic activity and cell membrane integrity, was not reduced, indicating that apoptosis rather than necrosis caused reduced number of haemocytes. It was concluded that apoptosis seemed to increase already after 5 days of 5 mg l−1 of Mn-exposure, although exposure for 10 days was required before it was reflected in the haemocyte numbers. Reduced numbers of haemocytes may increase the prevalencefor infections in N. norvegicus in their natural habitat.
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