| 51. |
- Larsson, D. G. Joakim, 1969, et al.
(författare)
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More male fish embryos near a pulp mill
- 2000
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 19:12, s. 2911-2917
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to endocrine disrupters during early life stages may cause severe long-term effects. One process likely to be affected is sexual differentiation, which in fish can be influenced by both exogenous androgens and estrogens. To investigate if sexual differentiation is disturbed in wild fish exposed to pollutants, we studied embryonic sex ratios in a viviparous, gonochoristic fish species, the eelpout (Zoarces viviparus), whose embryos complete sexual differentiation before birth. The normal sex ratio of the eelpout was close to 50% females at four reference stations. In the effluent gradient of a large Swedish pulp mill, however, the sex ratios were significantly male biased. In light of the endocrine disturbances found near several pulp and paper mills in Europe and North America, it is suggested that endocrine disrupters may interfere with sexual differentiation and, thereby, affect the reproductive potential of fish populations.
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| 52. |
- Larsson, D. G. Joakim, 1969, et al.
(författare)
-
Seasonal variations of vitelline envelope proteins, vitellogenin, and sex steroids in male and female eelpout (Zoarces viviparus).
- 2002
-
Ingår i: General and comparative endocrinology. - : Elsevier BV. - 0016-6480. ; 125:2, s. 184-96
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Tidskriftsartikel (refereegranskat)abstract
- The seasonal variations of vitelline envelope proteins, vitellogenin (VTG), and reproductive steroids were investigated in feral male and female eelpout, Zoarces viviparus. 17beta-Estradiol was present in both sexes with a peak in prespawning fish of 2.6 ng/ml in males and 2.7 ng/ml in females. 11-Ketotestosterone peaked in June at 4.2 and 0.47 ng/ml in males and females, respectively. A surge of testosterone was seen in both sexes in August, just prior to spawning. All steroid levels were low during early pregnancy. The vitelline envelope of the eelpout is composed of two major and one minor protein with molecular weights of 50, 55, and 44 kDa, respectively. An antiserum raised against solubilized vitelline envelope from turbot (Scophthalmus maximus) cross-reacted strongly with the 50-kDa protein from the isolated vitelline envelope and a similar-sized protein in female plasma and plasma from estrogenized males. Interestingly, the 50-kDa protein was also present at low levels in males as demonstrated by ELISA and Western blotting. In males, the 50-kDa protein did not follow the seasonal changes in 17beta-estradiol, but instead showed an almost perfect negative correlation with water temperature. VTG was present in female plasma as shown by Western blotting, but VTG was not detectable in male plasma despite relatively high endogenous estrogen levels. This suggests that the VTG induction by estradiol may be modulated by other factors in the eelpout.
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| 53. |
- Larsson, D. G. Joakim, 1969, et al.
(författare)
-
Studies of masculinization, detoxification, and oxidative stress responses in guppies (Poecilia reticulata) exposed to effluent from a pulp mill.
- 2002
-
Ingår i: Ecotoxicology and environmental safety. - : Elsevier BV. - 0147-6513. ; 52:1, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- Potential masculinization, detoxification, and oxidative stress responses were assessed in domesticated female guppies (Poecilia reticulata) exposed for 42 days to diluted effluent from a modern Swedish kraft pulp mill or a model androgen. Methyltestosterone induced male-like coloration and transformation of the anal fin into a gonopodium-like structure. The effluent did not induce any apparent changes of the anal fin morphology; however, the exposed guppies became more colored than control fish, which could be an androgenic response. A better understanding of the physiological mechanisms involved in these responses would be required for a full evaluation. Both primary effluent and effluent which had undergone activated sludge treatment caused a moderate but significant induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity. However, the general toxicity of both effluents was low, as mortality was negligible even at 25% dilutions. There was a continuous production of offspring in all groups (47-62% female fry), except by methyltestosterone-treated females, which did not reproduce. There were no indications that either effluent caused oxidative stress since hepatic glutathione reductase, glutathione S-transferase and DT-diaphorase activities remained unchanged compared with controls.
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| 54. |
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| 55. |
- Lehtonen, K. K., et al.
(författare)
-
The BEEP project in the Baltic Sea: Overview of results and outline for a regional biological effects monitoring strategy
- 2006
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 53:8-9, s. 523-537
-
Tidskriftsartikel (refereegranskat)abstract
- Field studies in the framework of the EU funded BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems, 2001-2004) aimed at validating and intercalibrating a battery of biomarkers of contaminant exposure and effects in selected indicator species in the Mediterranean, the North Atlantic and the Baltic Seas. Major strategic goals of the BEEP project were the development of a sensitive and cost-efficient biological effects monitoring approach, delivery of information and advice to end-user groups, and the implementation of a network of biomarker researchers around Europe. Based on the main results obtained in the Baltic Sea component of the BEEP the present paper summarises and assesses the applicability of biomarkers for different regions and species in this sea area. Moreover, a general strategy and some practical considerations for the monitoring of biological effects in the Baltic Sea are outlined. (c) 2006 Elsevier Ltd. All rights reserved.
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| 56. |
- Lennquist, Anna, 1978, et al.
(författare)
-
Colour and melanophore function in rainbow trout after long term exposure to the new antifoulant medetomidine
- 2010
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 80:9, s. 1050-1055
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Tidskriftsartikel (refereegranskat)abstract
- Medetomidine is a new antifouling agent, and its effects in non-target aquatic organisms have been investigated. Earlier short-term studies in fish have shown a skin lightening response to medetomidine, but effects after chronic exposure have not been studied. In fish, the dark pigment melanin is contained within specialized cells, melanophores. Medetomidine binds to the melanophore α2-adrenoceptor, which stimulates pigment aggregation resulting in the light appearance. In the present study, rainbow trout (Oncorhynchus mykiss) was long-term exposed to 0.5 and 5.0 nM of medetomidine via water for 54 d. The fish were then photographed for paleness quantification and the images were analyzed using ImageJ analysis software. Additionally, scales were removed and used for in vitro function studies of the melanophores, monitoring the response to melanophore stimulating hormone (MSH) and subsequent medetomidine addition. The number of melanophores was also investigated. As a result of the medetomidine exposure, fish from the 5 nM treatment were significantly paler than control fish and the melanophores from these fishes were also more aggregated. Melanophores from all the treatments were functional, responding to MSH by dispersion and to subsequent medetomidine by aggregation. However, the results indicate a difference in sensitivity among treatments. The number of melanophores in the scales did not change significantly after long term exposure to medetomidine. These results suggest that the observed paleness may be reversible, even after chronic exposure.
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| 57. |
- Lennquist, Anna, 1978, et al.
(författare)
-
Effects of medetomidine on hepatic EROD activity in three species of fish
- 2008
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513. ; 69:1, s. 74-79
-
Tidskriftsartikel (refereegranskat)abstract
- Medetomidine, an antifouling candidate, was investigated for its effects on cytochrome P4501A (CYP1A) activity in fish. Rainbow trout (Oncorhynchus mykiss), turbot (Psetta maxima), and Atlantic cod (Gadus morhua) were exposed to medetomidine either via i.p. injection (o5 mmol (1 mg)/kg) or via water (o50 nM). Enzyme activity was measured as ethoxyresorufin-O-deethylase (EROD) activity in liver microsomes. There was a small (2–7-fold) increase in EROD activity in rainbow trout. In turbot, EROD activity increased (4- fold) after injection, while a non-significant (50%) decrease was observed after water exposure. No effects on EROD activities were observed in Atlantic cod. In vitro inhibition studies of EROD activities in liver microsomes from all three species showed that medetomidine was a very potent CYP1A inhibitor. Thus, median inhibition values (IC50) were 35710nM for rainbow trout, 47717nM for turbot, and 111770nM for Atlantic cod. These observed effects suggest that medetomidine interferes with CYP1A-dependent metabolism of xenobiotics in these fish species.
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| 58. |
- Lennquist, Anna, 1978, et al.
(författare)
-
Physiology and mRNA expression in rainbow trout (Oncorhynchus mykiss) after long-term exposure to the new antifoulant medetomidine.
- 2011
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Ingår i: Comparative biochemistry and physiology. Toxicology & pharmacology : CBP. - : Elsevier BV. - 1532-0456. ; 154:3, s. 234-41
-
Tidskriftsartikel (refereegranskat)abstract
- Medetomidine is under evaluation for use as an antifouling agent, and its effects on non-target aquatic organisms are therefore of interest. In this study, rainbow trout was exposed to low (0.5 and 5.0nM) concentrations of medetomidine for up to 54days. Recently we have reported on effects on paleness and melanophore aggregation of medetomidine in these fish. Here, specific growth rates were investigated together with a broad set of physiological parameters including plasma levels of growth hormone (GH), insulin-like growth factor-I (IGF-I) and leptin, glucose and haemoglobin (Hb), hematocrit (Ht), condition factor, liver and heart somatic indexes (LSI, HSI). Hepatic enzyme activities of CYP1A (EROD activity), glutathione S-transferases (GST) and glutathione reductase (GR) were also measured. Additionally, hepatic mRNA expression was analysed through microarray and quantitative PCR in fish sampled after 31days of exposure. Medetomidine at both concentrations significantly lowered blood glucose levels and the higher concentration significantly reduced the LSI. The mRNA expression analysis revealed few differentially expressed genes in the liver and the false discovery rate was high. Taken together, the results suggest that medetomidine at investigated concentrations could interfere with carbohydrate metabolism of exposed fish but without any clear consequences for growth.
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| 59. |
- Lennquist, Anna, 1978, et al.
(författare)
-
Responses in fish exposed to medetomidine, a new antifouling agent
- 2010
-
Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 69, s. S43-S45
-
Tidskriftsartikel (refereegranskat)abstract
- Medetomidine is being introduced as a new antifouling agent. As part of a large risk assessment campaign, we have studied responses to medetomidine in a number of fish species. The studied parameters include respiration, blood parameters, antioxidant enzymes, CYP1A, behaviour, pigmentation, reproduction and growth. The main observations from these studies are: 1. Body paleness at water concentrations in the range of 0.5-50 nM, depending on species. In addition, impaired adaptation to the background colour was shown in fry from turbot and lumpfish. In rainbow trout, desensitization of melanophores (pigment cells) occurred in fish exposed to medetomidine for 21 days, but a prolonged study (54 days exposure time), showed that the melanophores were well functioning and in addition that no apoptosis had occurred. 2. CYP1A activities, measured as EROD activities, were increased at medetomidine water concentrations from 0.5-5 nM in rainbow trout, Atlantic salmon, turbot and three-spined stickleback. However, investigations in vitro showed medetomidine to be a potent inhibitor of EROD activity. 3. In lumpfish and turbot fry, a decreased oxygen consumption and respiration rate was observed from 2 nM medetomidine. This effect was reversible to a large extent.
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| 60. |
- Livingstone, D R, et al.
(författare)
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Development of hepatic CYP1A and blood vitellogenin in eel (Anguilla anguilla) for use as biomarkers in the Thames Estuary, UK.
- 2002
-
Ingår i: Marine environmental research. - 0141-1136. ; 50:1-5, s. 367-71
-
Tidskriftsartikel (refereegranskat)abstract
- The potential of eel (Anguilla anguilla) as a monitoring species for the Thames Estuary, UK, was examined. Hepatic cytochrome P4501A [7-ethoxyresorufin O-deethylase (EROD) activity] and blood vitellogenin (Western analysis) were investigated as biomarkers of exposure to, respectively, organic contaminants and to contaminants showing estrogenic activity. Hepatic microsomal EROD activities in A. anguilla from seven sites in the Thames Estuary in May 1998 varied three-fold (111 +/- 24 to 355 +/- 42 pmol min-1 mg protein-1) (mean +/- S.E.M.) and showed correlation with salinity; however, the latter relationship was not maintained at other times of the year. The range of EROD activities was two- to eight-fold higher than the 37 +/- 8 pmol min-1 mg-1 for A. anguilla from the relatively clean Tamar Estuary. beta-Naphthoflavone treatment (5 mg kg-1 wet wt.; 2 days) of Thames A. anguilla produced a two-fold increase in hepatic microsomal EROD activity. Comparing the Thames EROD data with those for A. anguilla from well-characterised contaminated sites in the Netherlands (Van der Oost, R., Goksøyr, A., Celander, M., Heida, H., & Vermeulen, N. P. E. 1996. Aquatic Toxicology, 36, 189-222), the Thames is suggested to be moderately impacted by polycyclic aromatic hydrocarbons and related contaminants. 17-beta-Estradiol treatment produced the appearance of a plasma protein of 211 Kd app. mol. wt. (recognised by antibodies to vitellogenin of Morone saxatilis), but putative vitellogenin could not be detected in A. anguilla from selected sites in the Thames Estuary.
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