Fish: UVB Protection Problems with SPMD blanks are being solved as deployment and transport methodologies improve. It appears that SPMDs and mussels may provide complementary pictures of water column contaminants when applied in concert. For example, simultaneous deployments of mussels and SPMDs may aid in distinguishing between dissolved and particle-bound lipophilic contaminants. Further correlations between these approaches should be explored. Acknowledgements We are grateful to MSc Leena WELLING,Institute for Environmental Research, University of Jyv~iskylii,Finland, for the OCC determinations. Personell of the Regional Laboratory of the Water and Environment District of Central Finland is acknowledged for their invaluable aid in work within the deployment. Dr. Harry PRESTis deeply grateful to the Analytical Division of the Hewlett-Packard Company and also to James N. HUCKINSfor encouragement and advice.
6 References [1] P. HEINONEN; J. PAASIVIRTA;S. HERVE:Periphyton and mussels [2]
[3]
[4] [5]
in monitoring chlorohydrocarbons and chlorophenols in watercourses. Toxicol. Environ. Chem. 11, 191 (1986) S. HERVE;P. HEINONEN;R. PAUKKU;M. KNUUTtLA;J. KOISTINEN; J. PAASIVIRTA:Mussel incubation method for monitoring organochlorine pollutants in watercourses. Four-year application in Finland. Chemosphere 17, 1945 (1988) A. SODERGREN:Solvent-filleddialysis membranes simulate uptake of pollutants by aquatic organisms. Environ. Sci. Technol. 21,855 (1987) A.S(SDERGREN:Monitoring of persistent, lipophilic pollutants in water and sediment with solvent-f'dleddialysis membranes. Ecotoxicol. Environ. Safety 19, 143 (1990) S. HERVE; R. PAUKKU;J. PAASMRTA;P. HEINONEN;A. S(SDERGREN:Uptake of organochlorines from lake water by hexane-filled dialysis membranes and by mussels. Chemosphere 22, 997 (1991)
Research Articles [6] J. N. HUCKINS;M. W. TUBERGEN;G. K. MANUWEERA:Semipermeable membrane devices containing model lipid: A new approach to monitoring the biovailabilityof lipophilic contaminants and estimating their biocencentration potential. Chemosphere 20,533 (1990) [7] H. F. PREST;W. M. JARMAN;S. A. BURNS;T. WEISSMOLLER;M. MARTIN; J. N. HUCKINS:Passive sampling via semipermeable membrane devices (SPMDs) in concert with bivalves in the Sacramento/ San Joaquin River Delta. Chemosphere 25, 1811 (1992) [8] S. HERVE: Mussel Incubation Method for Monitoring Organochlorine Compounds in Freshwater Recipient of Pulp and Paper Industry. Department of Chemistry, University of Jyviiskyl~i,Research Report 36, 1991, pp. 145 [9] J. PAASIVIRTA;A-L. RANTALAINEN;L. WELLING;S. HERVE;P. HEINONEN:Organochlorines as environmental tainting substances: taste panel study and chemical analyses of incubated mussels. Wat. Sci. Techn. 25, 105 (1992) [10] I. BAUER;S. WEIGELT;W. ERNST: Biotransformation of Hexachlorobenzene in the Blue Mussel (Mytilus edulis). Chemosphere 19, 1701 (1989) [11] E. C. WEn~ACH;J. J. GA~US: The interaction of uncoupling phenols with mitochondria and with mitochondrial protein. J. Biol. Chem. 240, 1811 (1965) [12] J. MEADOWS;D. TILLrr;J. N. HUCKINS;D. SCHROEDER:LargeScale Dialysis of Sample Lipids using the Semipermeable Membrane Device. Chemosphere 26, 1993 (1993) [13] J. N. HUCKINS;G. K. M~NUWEERA;J. D. PETTY;D. MACrAY; J. A. LEBO:Lipid-Containing Semipermeable Membrane Devices for Monitoring Organic Contaminants in Water. Environ. Sci. Technol. 27, 2489 (1993) [14] J. PAASIVIRTA;K. HEINOLA;T. HUMPPI;A. KARJALAINEN;J. KNUUTINEN;K. MANTYKOSK1;R. PAUKKU;T. PRLOLA;K. SURMA-AHo; J. TARHANEN;L. WELLING;H. VIHONEN:Polychlorinated Phenols, Guaiacols and Catechols in Environment. Chemosphere 14, 469 (1985)
Received: March 24, 1995 Accepted: April 3, 1995
Skin Component May Protect Fishes from Ultraviolet-B Radiation David L. Fabacher and Edward E. Little National Biological Service, Midwest Science Center, 4200 New Haven Road, Columbia, Missouri 65201, USA
Corresponding author: Dr. David L. Fabacher
Abstract. We observed a large peak of absorbance when methanol extracts of dorsal skin from four species of fish were scanned in a spectrophotometer. There appeared to be a direct relation between the amount of this skin component and the period of time in which each species of fish developed UVB-induced sunburn. Key words: Fish sunburn; UV-B-radiation;sunburn protection; UVB induced sunburn
1
Introduction
Stratospheric contamination by chlorofluorocarbons has re-
30
suited in ozone depletion, with the consequent increase in ultraviolet-B (UVB) radiation (280 to 320 nm) at the earth's surface [1]. The potential effects of increased UVB radiation on biological mechanisms have recendy been described [2, 3]. Depending on water clarity, UVB can penetrate the water column, placing aquatic organisms at risk to the harmful effects of UVB [4 - 6]. In a prior study sunburn was the first effect of simulated solar UVB radiation that we observed in rainbow trout (Oncorhynchus mykiss), Lahontan cutthroat trout (0. clarki henshawi), and Apache trout (O. apache) [7]. We now report on the exposure of razorback suckers (Xyrauchen texanus) to UVB radiation and examination of the dorsal skin from Apache trout, Lahontan cutt-
ESPR-Environ. Sci. & Pollut. Res. 2 (1) 30-32 (1995) 9 ecomedpublishers,D-86899 Landsberg,Germany
Research Articles
hroat trout, rainbow trout, and razorback suckers for the presence of a photoprotective factor.
2 2.1
Materials and Methods Animals
Fishes were obtained as eyed embryos, cultured at the Midwest Science Center and held under the same ambient lighting conditions (3200 lux) provided by indirect sunlight from windows and supplemental cool white fluorescent lamps. Juvenile fishes were examined for the presence of a photoprotective factor at 60 to 75 d after hatching. This was the earliest life stage that would be exposed to solar UVB in the water column, since earlier life stages would remain in the substrate. Apache trout were obtained from the Alchesay/Williams Creek National Hatchery (Arizona, USA) and had a mean total length [SE] of 4.7 cm [0.10] and a mean weight of 0.78 g [0.05]. Lahontan cutthroat trout were obtained from the Lahontan National Fish Hatchery (Nevada, USA) and had a mean total length of 4.4 cm [0.09] and a mean weight of 0.89 g [0.07]. Rainbow trout were obtained from the Saratoga National Fish Hatchery (Wyoming, USA) and had a mean total length of 4.8 cm [0.14] and a mean weight of 0.98 g [0.08] at the time of examination. Razorback suckers, an endangered freshwater species endogenous to the Colorado River basin, were obtained from the Dexter National Fish Hatchery (New Mexico, USA) and had a mean total length of 4.0 cm [0.05] and a mean weight of 0.58 g [0.04].
2.2
Exposure of Razorback Suckers
The solar simulator, experimental design, and procedures for exposure of razorback suckers were as previously described for Apache trout, Lahontan cutthroat trout, and rainbow trout (7). There were three exposure doses of 0.08, 3.42, and 6.43 J/cm2/day of UVB. Groups of five razorback suckers were stocked in open-top glass airlift chambers [8] for each of the three exposures. Three replicate groups were randomly distributed under the simulator and exposed for 21 d.
Fish: UVB Protection
gram, placed into a 13 - x 100 - m m glass test tube containing 2 ml of refrigerated 100 % methanol, and subjected to a Model SDT Tissumizer (Tekmar, Cincinnati, OH, USA) for about 1 min. Unshredded connective tissue was removed and discarded, and the methanol extract was centrifuged at 3000 rpm for 15 min at 20 ~ in a refrigerated centrifuge. After centrifugation the clear methanol supernatant was decanted into a vial, and the vial was capped and placed in a refrigerator; the pellet was discarded. 2.5
Absorption Spectroscopy
Chilled methanol extracts were scanned in a Beckman 5230 UV/vis recording spectrophotometer using difference spectroscopy. The approximate absorption maximum (~m~) of a skin component was calculated from the recording on the chart paper. Peak area was calculated using the formula 1/2 baseline x height to give a semi quantitative estimate of the amount. The results were expressed as area units/milligram wet weight of tissue.
2.6
Statistical Analyses
Statistical significance of the amount of component was determined by t-test and Duncan's multiple range test. The level of significance was selected at p ~ 0.05 [9].
3
Results and Discussion
In methanol extracts of the dorsal skin from Apache trout, Lahontan cutthroat trout, rainbow trout, and razorback suckers we observed a large peak within the UVB wavelength range ( ~ Fig. I). Observations were on five unexposed fish of each species. The mean 2max +_ SEM of this peak was 291.8 _+ 0.37 for Apache trout, 292.2 • 0.85 for Lahontan cutthroat trout, 291.8 _+ 0.38 for rainbow trout, and 292.8 • 0.36 for razorback suckers.
1.0
2.3
Removal of Skin From Four Species of Fish
Each of five unexposed fish of each species was euthanized in a container of ice water for 5 min, the water decanted off, and the container placed into a - 20 ~ freezer for about 1 min, which made the skin easier to remove because the fish was rigid. Under a binocular dissecting microscope, a fish was held on a watch glass with pointed forceps, the skin behind the head and opercula was punctured, and a small microscissors was used to cut a section of skin from the dorsal surface of the fish. This section of skin encompassed the area from just behind the head to the dorsal fin and just above the lateral lines and was peeled off the underlying musculature.
2.4
Extraction of Skin
Each dorsal skin section was weighed to the nearest milli-
ESPR- Environ. Sci. & Pollut. Res. 2 (1) 1995
ff 8
e~
0.0
,
,
,
&
&
200
300
400
5 0
6 0
Wavelength(nm)
700
Fig. 1 : Representation of UV-visible light absorption spectrum of dorsal skin methanol extract from fishes. Dotted lines are baseline (a) and height (b) of peak
31
Fish: UVB Protection
Research Articles
Dorsal skin m e t h a n o l extracts from Apache trout contained m o r e of this skin c o m p o n e n t than the extracts from L a h o n tan cutthroat trout o r r a i n b o w trout, while the methanol extracts from r a z o r b a c k suckers contained considerably m o r e than A p a c h e t r o u t (--' Table 1). W e found that r a z o r b a c k suckers d i d n o t develop sunburn after 21 days of exposure to simulated solar UVB o f up to 6.4 J / c m 2 / d a y . In a p r i o r study w i t h a simulated UVB dose of 6.4 J / c m 2 / d a y , rainb o w trout and L a h o n t a n cutthroat trout developed sunburn within 2 days and A p a c h e trout within 5 days [7].
tion as a first line of defense against UVB-induced sunburn in these fishes. The degree o f p h o t o p r o t e c t i o n w o u l d p r o b ably depend on the a m o u n t of c o m p o n e n t present (species and individuals with the least a m o u n t of this factor m a y be most at risk), as well as on the UVB dose. W e plan to identify this component and also determine if this component can be used as a b i o i n d i c a t o r to identify UVB-sensitive fish species.
3 Table 1: Amount of component in dorsal skin methanol extracts from unexposed fishes and the number of days to develop sunburn when fishes were exposed to a simulated UVB dose of 6.4 J/cm2/day. Species
Amount of Component a
Days to Sunburn
Rainbow trout
23.9 [2,8]A b
2
Lahontan cutthroat trout
23.9 [1,2]A
2
Apache trout
49.6 [7.8]B
5
Razorback sucker
101.2 [3.8]C
> 21
a Values are mean [SE] area units/milligram wet weight of tissue for five fish of each species. b Means with the same letter are not significantly different.
O u r d a t a indicate a strong relationship between the a m o u n t o f this c o m p o n e n t in m e t h a n o l extracts of dorsal skin from the four species o f fish e x a m i n e d and the p e r i o d of time it t o o k for them to develop UVB-induced sfinburn. Similar to o u r o b s e r v a t i o n s , Bullock [10] also observed considerable variability in response of individual r a i n b o w trout to intense simulated solar r a d i a t i o n a n d suggested that the ability of some fish to tolerate the r a d i a t i o n m a y result from elevated levels of a p h o t o p r o t e c t i v e factor of genetic origin. T h e skin c o m p o n e n t we observed m a y function as the p h o t o p r o t e c tive factor suggested by Bullock [10].
4
References
[1] KERR,J. B.; C. T. MCELROY: Evidence for large upward trends of ultraviolet-B radiation linked to ozone depletion. Science, 262: 1032- 1034 (1993). [2] SCOPE: Effects of increased ultraviolet radiation on biological systems. SCOPE, 51 bd de Montmorency, 75016 Paris, France (1992). [3] SCOPE: Effects of increased ultraviolet radiation on global ecosystems. SCOPE, 51 bd de Montmorency, 75016 Paris, France (1993). [4] SMITH, g. C.; B. B. PREZELIN; K. S. BAKER; R. R. BIDIGARE; N. P. BOUCHER;T. COLEY; D. KARENTZ;S. MACINTYRE;H. A. MATLICK;D. MENZIES;M. ONDRUSEK;Z. WAN; K. J. WATERS: Ozone depletion: ultraviolet radiation and phytoplankton biology in antarctic waters. Science, 255: 952-959 (1992). [5] GLEASON,D. F.; G. M. WELLINCTON:Ultraviolet radiation and coral bleaching. Nature, 365: 836-838 (1993). [6] HADER, D.: Effects of enhanced solar radiation on aquatic ecosystems. In M. TEVINI, (Ed.), UV-B radiation and ozone depletion: effects on humans, animals, plants, microorganisms, and materials, Lewis publishers, Boca Raton, Florida, pp. 155-192 (1993). [7] LITTLE,E. E.; D. L. FABACHER:Comparative sensitivity of rainbow trout and two threatened salmonids, Apache trout and Lahontan cutthroat trout, to ultraviolet-B radiation. Arch. Hydrobiology, 4 3 , 2 1 7 - 2 2 6 (1994). [8] CLEVELAND, L.; E.E. LITTLE; C.G. INGERSOLL; R.H. WIEDMEYER;J. B. HUNN: Sensitivity of brook trout to low pH, low calcium and elevated aluminum concentrations during laboratory pulse exposures. Aquat. Toxicol. 19, 303 - 318 (1991). [9] SNEDECOR,G. W.; W. G. COCHRAN:Statistical methods. 7th edition. Iowa State University Press, Ames, Iowa (1980). [10] BULLOCK, A. M.: Solar ultraviolet radiation: a potential environmental hazard in the cultivation of farmed finfish. In MUIR, J. E. and ROBERTS,R. J. (eds.), Recent Advances in Aquaculture, volume 3, Croom Helm, Beckenham, Kent, pp 139 - 224 (1988).
Conclusion and Future Outlook Received: December 9, 1994 Accepted: December 30, 1994
O u r findings indicate that this skin c o m p o n e n t m a y func-
LIFECYCLEASSESSME
NEW
$,
The International Journal of Life Cycle Assessment is the first journal devoted entirely to LCA. LCA has become a recognized instrument to assess the ecological burdens and impacts connected with products and systems, or, more general, with human activities. The LCA-Journal is a forum for - Scientists developing LCA, - LCA practitioners, - Managers concerned with environmental aspects of products, - Governmental environmental agencies responsible for product quality, - Scientific and industrial societies involved in LCA development, - Ecological institutions and bodies ISSN 0948-3349
32
For further information please contact 9 ecomed publishers 9 Rudolf-DieseI-StraBe 3 D-86899 Landsberg, Germany 9Tel. +49-8191-125-500 9 Fax §
ESPR-Environ. Sci. & Pollut. Res. 2 (1) 1995
6 References [1] P. HEINONEN; J. PAASIVIRTA;S. HERVE:Periphyton and mussels [2]
[3]
[4] [5]
in monitoring chlorohydrocarbons and chlorophenols in watercourses. Toxicol. Environ. Chem. 11, 191 (1986) S. HERVE;P. HEINONEN;R. PAUKKU;M. KNUUTtLA;J. KOISTINEN; J. PAASIVIRTA:Mussel incubation method for monitoring organochlorine pollutants in watercourses. Four-year application in Finland. Chemosphere 17, 1945 (1988) A. SODERGREN:Solvent-filleddialysis membranes simulate uptake of pollutants by aquatic organisms. Environ. Sci. Technol. 21,855 (1987) A.S(SDERGREN:Monitoring of persistent, lipophilic pollutants in water and sediment with solvent-f'dleddialysis membranes. Ecotoxicol. Environ. Safety 19, 143 (1990) S. HERVE; R. PAUKKU;J. PAASMRTA;P. HEINONEN;A. S(SDERGREN:Uptake of organochlorines from lake water by hexane-filled dialysis membranes and by mussels. Chemosphere 22, 997 (1991)
Research Articles [6] J. N. HUCKINS;M. W. TUBERGEN;G. K. MANUWEERA:Semipermeable membrane devices containing model lipid: A new approach to monitoring the biovailabilityof lipophilic contaminants and estimating their biocencentration potential. Chemosphere 20,533 (1990) [7] H. F. PREST;W. M. JARMAN;S. A. BURNS;T. WEISSMOLLER;M. MARTIN; J. N. HUCKINS:Passive sampling via semipermeable membrane devices (SPMDs) in concert with bivalves in the Sacramento/ San Joaquin River Delta. Chemosphere 25, 1811 (1992) [8] S. HERVE: Mussel Incubation Method for Monitoring Organochlorine Compounds in Freshwater Recipient of Pulp and Paper Industry. Department of Chemistry, University of Jyviiskyl~i,Research Report 36, 1991, pp. 145 [9] J. PAASIVIRTA;A-L. RANTALAINEN;L. WELLING;S. HERVE;P. HEINONEN:Organochlorines as environmental tainting substances: taste panel study and chemical analyses of incubated mussels. Wat. Sci. Techn. 25, 105 (1992) [10] I. BAUER;S. WEIGELT;W. ERNST: Biotransformation of Hexachlorobenzene in the Blue Mussel (Mytilus edulis). Chemosphere 19, 1701 (1989) [11] E. C. WEn~ACH;J. J. GA~US: The interaction of uncoupling phenols with mitochondria and with mitochondrial protein. J. Biol. Chem. 240, 1811 (1965) [12] J. MEADOWS;D. TILLrr;J. N. HUCKINS;D. SCHROEDER:LargeScale Dialysis of Sample Lipids using the Semipermeable Membrane Device. Chemosphere 26, 1993 (1993) [13] J. N. HUCKINS;G. K. M~NUWEERA;J. D. PETTY;D. MACrAY; J. A. LEBO:Lipid-Containing Semipermeable Membrane Devices for Monitoring Organic Contaminants in Water. Environ. Sci. Technol. 27, 2489 (1993) [14] J. PAASIVIRTA;K. HEINOLA;T. HUMPPI;A. KARJALAINEN;J. KNUUTINEN;K. MANTYKOSK1;R. PAUKKU;T. PRLOLA;K. SURMA-AHo; J. TARHANEN;L. WELLING;H. VIHONEN:Polychlorinated Phenols, Guaiacols and Catechols in Environment. Chemosphere 14, 469 (1985)
Received: March 24, 1995 Accepted: April 3, 1995
Skin Component May Protect Fishes from Ultraviolet-B Radiation David L. Fabacher and Edward E. Little National Biological Service, Midwest Science Center, 4200 New Haven Road, Columbia, Missouri 65201, USA
Corresponding author: Dr. David L. Fabacher
Abstract. We observed a large peak of absorbance when methanol extracts of dorsal skin from four species of fish were scanned in a spectrophotometer. There appeared to be a direct relation between the amount of this skin component and the period of time in which each species of fish developed UVB-induced sunburn. Key words: Fish sunburn; UV-B-radiation;sunburn protection; UVB induced sunburn
1
Introduction
Stratospheric contamination by chlorofluorocarbons has re-
30
suited in ozone depletion, with the consequent increase in ultraviolet-B (UVB) radiation (280 to 320 nm) at the earth's surface [1]. The potential effects of increased UVB radiation on biological mechanisms have recendy been described [2, 3]. Depending on water clarity, UVB can penetrate the water column, placing aquatic organisms at risk to the harmful effects of UVB [4 - 6]. In a prior study sunburn was the first effect of simulated solar UVB radiation that we observed in rainbow trout (Oncorhynchus mykiss), Lahontan cutthroat trout (0. clarki henshawi), and Apache trout (O. apache) [7]. We now report on the exposure of razorback suckers (Xyrauchen texanus) to UVB radiation and examination of the dorsal skin from Apache trout, Lahontan cutt-
ESPR-Environ. Sci. & Pollut. Res. 2 (1) 30-32 (1995) 9 ecomedpublishers,D-86899 Landsberg,Germany
Research Articles
hroat trout, rainbow trout, and razorback suckers for the presence of a photoprotective factor.
2 2.1
Materials and Methods Animals
Fishes were obtained as eyed embryos, cultured at the Midwest Science Center and held under the same ambient lighting conditions (3200 lux) provided by indirect sunlight from windows and supplemental cool white fluorescent lamps. Juvenile fishes were examined for the presence of a photoprotective factor at 60 to 75 d after hatching. This was the earliest life stage that would be exposed to solar UVB in the water column, since earlier life stages would remain in the substrate. Apache trout were obtained from the Alchesay/Williams Creek National Hatchery (Arizona, USA) and had a mean total length [SE] of 4.7 cm [0.10] and a mean weight of 0.78 g [0.05]. Lahontan cutthroat trout were obtained from the Lahontan National Fish Hatchery (Nevada, USA) and had a mean total length of 4.4 cm [0.09] and a mean weight of 0.89 g [0.07]. Rainbow trout were obtained from the Saratoga National Fish Hatchery (Wyoming, USA) and had a mean total length of 4.8 cm [0.14] and a mean weight of 0.98 g [0.08] at the time of examination. Razorback suckers, an endangered freshwater species endogenous to the Colorado River basin, were obtained from the Dexter National Fish Hatchery (New Mexico, USA) and had a mean total length of 4.0 cm [0.05] and a mean weight of 0.58 g [0.04].
2.2
Exposure of Razorback Suckers
The solar simulator, experimental design, and procedures for exposure of razorback suckers were as previously described for Apache trout, Lahontan cutthroat trout, and rainbow trout (7). There were three exposure doses of 0.08, 3.42, and 6.43 J/cm2/day of UVB. Groups of five razorback suckers were stocked in open-top glass airlift chambers [8] for each of the three exposures. Three replicate groups were randomly distributed under the simulator and exposed for 21 d.
Fish: UVB Protection
gram, placed into a 13 - x 100 - m m glass test tube containing 2 ml of refrigerated 100 % methanol, and subjected to a Model SDT Tissumizer (Tekmar, Cincinnati, OH, USA) for about 1 min. Unshredded connective tissue was removed and discarded, and the methanol extract was centrifuged at 3000 rpm for 15 min at 20 ~ in a refrigerated centrifuge. After centrifugation the clear methanol supernatant was decanted into a vial, and the vial was capped and placed in a refrigerator; the pellet was discarded. 2.5
Absorption Spectroscopy
Chilled methanol extracts were scanned in a Beckman 5230 UV/vis recording spectrophotometer using difference spectroscopy. The approximate absorption maximum (~m~) of a skin component was calculated from the recording on the chart paper. Peak area was calculated using the formula 1/2 baseline x height to give a semi quantitative estimate of the amount. The results were expressed as area units/milligram wet weight of tissue.
2.6
Statistical Analyses
Statistical significance of the amount of component was determined by t-test and Duncan's multiple range test. The level of significance was selected at p ~ 0.05 [9].
3
Results and Discussion
In methanol extracts of the dorsal skin from Apache trout, Lahontan cutthroat trout, rainbow trout, and razorback suckers we observed a large peak within the UVB wavelength range ( ~ Fig. I). Observations were on five unexposed fish of each species. The mean 2max +_ SEM of this peak was 291.8 _+ 0.37 for Apache trout, 292.2 • 0.85 for Lahontan cutthroat trout, 291.8 _+ 0.38 for rainbow trout, and 292.8 • 0.36 for razorback suckers.
1.0
2.3
Removal of Skin From Four Species of Fish
Each of five unexposed fish of each species was euthanized in a container of ice water for 5 min, the water decanted off, and the container placed into a - 20 ~ freezer for about 1 min, which made the skin easier to remove because the fish was rigid. Under a binocular dissecting microscope, a fish was held on a watch glass with pointed forceps, the skin behind the head and opercula was punctured, and a small microscissors was used to cut a section of skin from the dorsal surface of the fish. This section of skin encompassed the area from just behind the head to the dorsal fin and just above the lateral lines and was peeled off the underlying musculature.
2.4
Extraction of Skin
Each dorsal skin section was weighed to the nearest milli-
ESPR- Environ. Sci. & Pollut. Res. 2 (1) 1995
ff 8
e~
0.0
,
,
,
&
&
200
300
400
5 0
6 0
Wavelength(nm)
700
Fig. 1 : Representation of UV-visible light absorption spectrum of dorsal skin methanol extract from fishes. Dotted lines are baseline (a) and height (b) of peak
31
Fish: UVB Protection
Research Articles
Dorsal skin m e t h a n o l extracts from Apache trout contained m o r e of this skin c o m p o n e n t than the extracts from L a h o n tan cutthroat trout o r r a i n b o w trout, while the methanol extracts from r a z o r b a c k suckers contained considerably m o r e than A p a c h e t r o u t (--' Table 1). W e found that r a z o r b a c k suckers d i d n o t develop sunburn after 21 days of exposure to simulated solar UVB o f up to 6.4 J / c m 2 / d a y . In a p r i o r study w i t h a simulated UVB dose of 6.4 J / c m 2 / d a y , rainb o w trout and L a h o n t a n cutthroat trout developed sunburn within 2 days and A p a c h e trout within 5 days [7].
tion as a first line of defense against UVB-induced sunburn in these fishes. The degree o f p h o t o p r o t e c t i o n w o u l d p r o b ably depend on the a m o u n t of c o m p o n e n t present (species and individuals with the least a m o u n t of this factor m a y be most at risk), as well as on the UVB dose. W e plan to identify this component and also determine if this component can be used as a b i o i n d i c a t o r to identify UVB-sensitive fish species.
3 Table 1: Amount of component in dorsal skin methanol extracts from unexposed fishes and the number of days to develop sunburn when fishes were exposed to a simulated UVB dose of 6.4 J/cm2/day. Species
Amount of Component a
Days to Sunburn
Rainbow trout
23.9 [2,8]A b
2
Lahontan cutthroat trout
23.9 [1,2]A
2
Apache trout
49.6 [7.8]B
5
Razorback sucker
101.2 [3.8]C
> 21
a Values are mean [SE] area units/milligram wet weight of tissue for five fish of each species. b Means with the same letter are not significantly different.
O u r d a t a indicate a strong relationship between the a m o u n t o f this c o m p o n e n t in m e t h a n o l extracts of dorsal skin from the four species o f fish e x a m i n e d and the p e r i o d of time it t o o k for them to develop UVB-induced sfinburn. Similar to o u r o b s e r v a t i o n s , Bullock [10] also observed considerable variability in response of individual r a i n b o w trout to intense simulated solar r a d i a t i o n a n d suggested that the ability of some fish to tolerate the r a d i a t i o n m a y result from elevated levels of a p h o t o p r o t e c t i v e factor of genetic origin. T h e skin c o m p o n e n t we observed m a y function as the p h o t o p r o t e c tive factor suggested by Bullock [10].
4
References
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Conclusion and Future Outlook Received: December 9, 1994 Accepted: December 30, 1994
O u r findings indicate that this skin c o m p o n e n t m a y func-
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