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Archives of Environmental Contamination and Toxicology (v.39, #2)
Experimental Kinetic Rates of Food-Chain and Waterborne Radionuclide Transfer to Freshwater Fish: A Basis for the Construction of Fish Contamination Charts by J. Garnier-Laplace; C. Adam; J. P. Baudin (pp. 133-144).
A standardized procedure is proposed to obtain from laboratory experiments the kinetic accumulation and release rates necessary to calibrate dynamic models to quantify radionuclide direct and trophic transfer in fish. The model takes into account the food-chain effect, the feeding rate, and the growth of organisms. It takes as examples 54Mn, 60Co, and 137Cs transfer dynamics through a simple pelagic food-chain (phytoplankton, zooplankton, prey fish, and predator fish). The estimated kinetic rates used in quantifying all the transfers of the three radioactive pollutants through the pelagic food chain are compared from the radioecological point of view. For fish, comparison was based on the calculation of concentration factors referring to direct transfer from water and trophic transfer factors. For the prey fish and the predator fish, direct transfer gave the following order for accumulation 60Co < 137Cs < 54Mn. Values reached at equilibrium in L/kg WW were respectively for the prey fish and the predator fish: 8.7 < 27.4 < 107 and 4.14 < 6.59 < 13.4. For the trophic route, 137Cs is the most accumulated (TTF eq = 0.485 in 291 days for the prey fish and TTF eq = 1.45 in 17 years for the predator fish). A sensitivity analysis adapted to the case of a chronic contamination scenario of a watercourse was run. It showed that the phytoplankton biomass, the contact time of these drifting particles from a release point to the station where they are ingested and the feeding rates of the fish are the most influential parameter with regard to the concentration in fish, whatever the trophic level. Contamination charts are constructed for the predator fish to illustrate the relationship between the most influential ecological parameters and the radionuclide concentration in fish for simple contamination scenarios. They are shown to be effective tools for helping in the choice of the most relevant value of aggregated concentration factors (ACFs: radionuclide concentration ratio between the organism and the water, referred to steady-state and to all possible transfer pathways) for a given key ecological situation in a given ecosystem. An example is given of a simple chronic release scenario of 1 Bq/L and a phytoplanktonic bloom period. For 137Cs, the ACF increases with increasing contact time and increasing feeding rate, to nearly 550 L/kg WW at equilibrium. For 54Mn, ACF reaches 65 L/kg WW. For 60Co, the general pattern of the relationship is due to the rapid kinetic rates governing the distribution of the radionuclide between dissolved and solid (phytoplankton) phases with a maximum value for ACF of 7.2 L/kg WW for the case study. Analysis of these charts provides a basis for overall guidelines for chronic releases in a given watercourse.
Membrane Lipid Composition of Bacillus stearothermophilus as Affected by Lipophilic Environmental Pollutants: An Approach to Membrane Toxicity Assessment by M. M. Donato; A. S. Jurado; M. C. Antunes-Madeira; V. M. C. Madeira (pp. 145-153).
The thermophilic eubacterium Bacillus stearothermophilus is used as a model to identify membrane perturbing effects of lipophilic compounds. A parallelism has been established between the toxicity of the organochlorine insecticide DDT and its metabolite, DDE, in bacterial growth and the effects on cell functions and physical perturbations induced at the membrane (Donato et al. 1997a, Arch Environ Contam Toxicol 33:109–116; Donato et al. 1997b, Appl Environ Microbiol 63:4948–495). In the present work, the use of B. stearothermophilus as a model of screening for chemical toxicity has been implemented. Because the regulation of the lipid composition of the membrane is a common strategy in response to adverse growth conditions, we studied the effects of DDE on the lipid composition and the consequent alterations of membrane physical properties in comparison to the parental compound DDT. As expected, different adaptation responses were induced by the compounds, being DDT more effective as compared with DDE. Collected data are consistent with the stronger perturbations induced by DDT on growth and membrane functions. It is concluded that the membrane lipid composition of the bacterium is a very sensitive criterium to detect membrane-mediated toxic effects at low concentrations of lipophilic xenobiotics.
A Phytotoxicity Test Using Transpiration of Willows by S. Trapp; K. C. Zambrano; K. O. Kusk; U. Karlson (pp. 154-160).
A short-term acute toxicity assay for willow trees growing in contaminated solution or in polluted soil was developed and tested. The test apparatus consists of an Erlenmeyer flask with a prerooted tree cutting growing in it. Growth and reduction of transpiration are used to determine toxicity. Transpiration is closely related to photosynthesis and growth, but is easier and faster to measure and can be measured without disturbance of the test system. Plants are grown for 24 h in uncontaminated nutrient solution before the toxicant is added to determine the initial transpiration. The loss of weight is expressed as % decrease after 48 and 72 h or longer compared to the initial transpiration, divided by the transpiration of control plants. More toxicity parameters are growth and water use efficiency of the plants. The sensitivity of the test was evaluated with 3,5-dichlorophenol. EC50 values between 5.8 and 9.6 mg/L were found. This is similar to the results from algal growth rate tests. The willow tree toxicity test may be useful for determining the site-specific toxicity of polluted soils and for terrestrial risk assessment of new chemicals and pesticides.
Monitoring of Urban Traffic Emissions Using Some Physiological Indicators in Ricinus communis L. Plants by J. Kammerbauer; T. Dick (pp. 161-166).
Plants of Ricinus communis L. in the city of Porto Alegre, in southern Brazil, were exposed to urban traffic exhaust emissions for 5 months and compared with controls kept at a site essentially free of direct motor vehicle emissions. No symptomatic visible injuries were observed, but significant differences could be measured in growth, enzymatic activities of total peroxidase and nitrate reductase, chlorophyll content, leaf buffering capacity, and N contents in leaves. Additionally, these data were compared with results from fumigation experiments under controlled conditions. The study showed that some physiological parameters in R. communis L. plants could be used as an appropriate bioindicator system for urban traffic contamination, and therefore it is recommended that dose-response relationships should be developed.
Heavy Metal Toxicity and Differential Effects on the Hyperglycemic Stress Response in the Shrimp Palaemon elegans by S. Lorenzon; M. Francese; E. A. Ferrero (pp. 167-176).
Agricultural and industrial activities cause heavy metal pollution of the aquatic environment. The sensitivity of crustaceans to heavy metals is well documented. However, the hormonal and metabolic target of physiological functions affected by sublethal toxicity and stress responses have been scarcely investigated. Exposure of Palaemon elegans to increasing concentrations of heavy metals dissolved in artificial sea water resulted in an order of toxicity tested by LC50 for 96 h in intact and eyestalkless animals in which Hg is the most toxic, followed by Cd, Cu, Zn, and Pb. Eyestalkless animals were found to be more sensitive than intact individuals. Heavy metals affect the blood glucose levels, yet manipulative stress does not. The intermediate sublethal concentrations of Hg, Cd, and Pb produced significant hyperglycemic responses within 3 h, while the highest concentrations elicited no hyperglycemia in 24 h. In contrast, animals exposed to Cu and Zn showed hyperglycemia even at high concentrations. This difference in response between Cu or Zn and the nonessential heavy metals Cd, Hg, or Pb can probably be explained by the physiological roles of the former in crustaceans and by tolerance adaptations. Involvement of the crustacean hyperglycemic hormone (cHH) was tested by routine bioassay on eyestalkless individuals; each group was injected with a two-eyestalk-equivalent extract from control animals or from shrimp exposed to high concentrations of Cd, Hg, Pb, or low concentrations of Cu or Zn. All showed a hyperglycemic response within 2 h. In contrast, extracts of eyestalk removed from animals that had developed a full hyperglycemic reaction after exposure to low concentrations of Hg, Cd, Pb, or high concentrations of Cu and Zn were depleted of cHH as shown by the attenuation of the response after injection of the extracts into eyestalkless animals. This generalized and predictable sublethal response can be used as a quantitative physiological biomarker for water quality monitoring assessment.
Effects of Sustained-Release Methoprene and a Combined Formulation of Liquid Methoprene and Bacillus thuringiensis israelensis on Insects in Salt Marshes by S. P. Lawler; D. A. Dritz; T. Jensen (pp. 177-182).
Aquatic insects are an important component of the food web in salt marshes, therefore it is necessary to test whether pesticides used to control mosquitoes in salt marshes are safe for nontarget insects. We tested the nontarget effects of a combined formulation (duplex) of Bacillus thuringiensis israelensis (B.t.i.) and liquid methoprene (an insect development regulator) or sustained-release methoprene pellets (Altosid® pellets) by applying these materials to replicated salt marsh ponds at maximum label rates. Untreated ponds served as controls. We measured effects of the pesticides by rearing immature mosquitoes (Aedes dorsalis) and water boatmen (Trichocorixa reticulata) in predator-exclusion cages and by monitoring uncaged populations of invertebrates using replicated sweep-net samples. Both pesticides killed caged mosquitoes, and the activity of the Altosid® pellets continued through 99 days. There were no detectable effects of either pesticide on the survival or maturation of T. reticulata, or on abundances of uncaged invertebrates. The long-term activity of the pellets could help minimize mosquito abatement activity in salt marshes where there are breeding birds or endangered species. However, other studies suggest that this advantage needs to be balanced against the risks that sustained-release formulations could lead to development of resistance in mosquitoes or that initially undetected nontarget effects could build over time.
Accumulation of Nitrite in the Tissues of Penaeus monodon Exposed to Elevated Ambient Nitrite After Different Time Periods by S.-Y. Cheng; J.-C. Chen (pp. 183-192).
Penaeus monodon (29.42 ± 0.39 g) that had been exposed individually to 0.001 (control), 0.07, 0.36, 0.72, and 1.44 mM nitrite in 25 ppt sea water were examined for the nitrite accumulation in hemolymph, gill, eyestalk, heart, foregut, midgut, hepatopancreas, and muscle and nitrite uptake after 1, 3, 6, 12, 24, and 48 h, respectively. Concentration of nitrite in the tissues increased directly with ambient nitrite and exposure time except for muscle. P. monodon following 48-h exposure to 0.36 mM nitrite, nitrite concentration progressively increased from the muscle (0.40 μmol/g), hepatopancreas (1.24 μmol/g), gill (1.82 μmol/g), foregut (2.03 μmol/g), hemolymph (0.39 μmol/mL), heart (2.43 μmol/g), eyestalk (3.07 μmol/g), and to the midgut (4.14 μmol/g), which is 1.1, 3.4, 5.0, 5.6, 6.6, 6.8, 8.5, and 11.4 times the ambient nitrite concentration, respectively. It is concluded that when P. monodon is exposed to ambient nitrite, nitrite is immediately incorporated in the hemolymph and midgut via branchial chloride uptake of NO2 −, and accumulated in the tissues.
Detrimental Effects Associated with Trace Element Uptake in Lake Chubsuckers (Erimyzon sucetta) Exposed to Polluted Sediments by W. A. Hopkins; J. W. Snodgrass; J. H. Roe; B. P. Jackson; J. C. Gariboldi; J. D. Congdon (pp. 193-199).
Lake chubsuckers (Erimyzon sucetta) were exposed to coal ash–polluted sediments under conservative experimental conditions (filtered artificial soft water and abundant uncontaminated food). After 4 months of exposure, fish grazing the polluted sediments had significantly elevated body burdens of Se, Sr, and V. Selenium levels were particularly elevated, reaching mean whole body concentrations of 5.6 μg/g dry mass by the end of experimental manipulations. Twenty-five percent of fish exposed to pollutants died during the study. All surviving fish exposed to ash exhibited substantial decreases in growth and severe fin erosion. Total nonpolar lipids were two times higher in fish from the control treatment, but percent lipid did not differ between treatments. Because fish were presented with the same amount of food during the study, it appears fish exposed to ash utilized more energy for daily activities and/or were less efficient at converting available energy to tissues for growth and storage. The results were particularly interesting because we were unable to detect differences in standard metabolic rate (SMR) of fish between treatments. Increased energy expenditures not detectable in estimates of maintenance based on SMR, such as costs of digestion or activity, may have contributed to decreased energetic efficiency. Our findings corroborate previous studies which have documented the toxicity of ash-derived pollutants in fish.
Mercury in Feathers of Audouin's Gull (Larus audouinii) Chicks from Northeastern Mediterranean Colonies by V. Goutner; R. W. Furness; K. Papakonstantinou (pp. 200-204).
Feathers of Audouin's gull chicks from three Aegean island areas (north Dodecanese, Cyclades, Kythera) Greece, were sampled in 1997 and 1998 and analyzed for mercury. Mean concentrations varied from 0.94 μg/g (Lipsos, Dodecanese, 1998) to 2.14 μg/g (Paros, Cyclades, 1998). Significant differences between years occurred in some regions (Lipsos, Fourni) but not in others (Paros). Within each year, especially in 1998, mean mercury concentrations differed among colonies. Results did not support the prediction that mercury levels would be higher in the north Dodecanese area due to the proximity of the polluted Menderes delta. There was no relationship between estimated chick age and feather mercury contents (r =−0.04, NS). Detected mercury levels do not seem to pose any toxic hazard to the Aegean Audouin's gull populations. However, the ease of sampling from gulls indicates that they may be a useful biomonitor of mercury contamination in this region.
Transfer of DDT and Metabolites from Fruit Orchard Soils to American Robins (Turdus migratorius) Twenty Years After Agricultural Use of DDT in Canada by M. L. Harris; L. K. Wilson; J. E. Elliott; C. A. Bishop; A. D. Tomlin; K. V. Henning (pp. 205-220).
Wildlife contamination studies found high levels of DDT and associated metabolites in bird eggs from Canadian orchard sites during the early 1990s. The present study investigated local dietary uptake of DDT and geographic variability in tissue concentrations in the same orchards. A soil–earthworm–robin food chain was chosen for study, as early surveys showed that robins contained the highest levels of DDT of several avian species and because published research indicated that earthworms were a probable dietary exposure route. Organochlorine pesticides and PCBs were measured in soil, earthworm, robin egg, and robin nestling samples collected from fruit orchards and reference sites. High average DDE (soil: 5.2 mg/kg; earthworm: 52 mg/kg; robin egg: 484 mg/kg dry weight) and DDT (soil: 9.2 mg/kg; earthworm: 21 mg/kg; robin egg: 73 mg/kg dry weight) concentrations in Okanagan (British Columbia) samples confirmed that previously recorded contamination was common in the region. Concentrations detected in Simcoe, Ontario, orchards were not as high but were still significantly elevated relative to levels in soils and robins from reference areas. Significant positive linear regressions between soil and earthworm concentrations and consistent trends in food chain accumulation suggested that robins were acquiring DDT and metabolite (DDTr) burdens locally. Low concentrations of DDT and DDTr in robin eggs collected from nests in nearby nonorchard and post-DDT orchard habitats suggested that the local sources were in orchards. Persistence of DDT in orchard food chains is likely due to a combination of retarded degradation rates for DDT in soil and its extensive use historically. DDT concentrations in some robin eggs and earthworms were at levels comparable to those observed in field studies where mortality or reproductive effects occurred.
Developmental Toxicity of Lead-Contaminated Sediment to Mallard Ducklings by D. J. Hoffman; G. H. Heinz; L. Sileo; D. J. Audet; J. K. Campbell; L. J. LeCaptain (pp. 221-232).
Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard (Anas platyrhynchos) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 μg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.
Differential Toxicities of Organophosphate and Carbamate Insecticides in the Nestling European Starling (Sturnus vulgaris) by M. L. Parker; M. I. Goldstein (pp. 233-242).
The concept of B-esterase buffering against anti-cholinesterase (ChE) insecticide toxicity has been extensively researched in mammalian species. Presumably due to relatively low levels of anti-ChE detoxifying enzyme activity in birds, however, avian species are often more susceptible to the toxic effects of these compounds. We quantified B-esterase buffering of organophosphate (diazinon and methyl parathion) and carbamate (aldicarb and oxamyl) toxicity in nestling European starlings (Sturnus vulgaris). The differential toxicities were studied using mortality, behavioral observation, and inhibitor affinity data. The toxicities of diazinon, methyl parathion, and oxamyl were affected by the removal of butyrylcholinesterase (BChE) using the specific inhibitor tetraisopropylpyrophosphoramide (iso-OMPA). When BChE was absent, aldicarb toxicity was not affected. Theoretically, compounds affected by BChE removal would have a higher affinity for BChE or carboxylesterase (CaE) than acetylcholinesterase (AChE). However, this was only the case for diazoxon, which had a 1,000-fold higher affinity for plasma BChE and CaE than AChE. Methyl paraoxon and aldicarb had a higher affinity for plasma AChE than for BChE or CaE. Oxamyl had similar IC50 values for all three enzymes studied. The generation of IC50 curves for each inhibitor revealed the presence of nonsensitive forms of CaE in both the plasma and brain. Based on the results of this research, there appears to be no strict correlation between mortality data and inhibitor affinities for each esterase that alone can explain the differential toxicities of these compounds.
Increased Production of Proinflammatory Cytokines by Murine Macrophages Following Oral Exposure to Sodium Selenite But Not to Seleno-L-Methionine by V. J. Johnson; M. Tsunoda; R. P. Sharma (pp. 243-250).
Selenium (Se) is an essential as well as a toxic trace element in animal and human nutrition. The immune system is a known target of Se intoxication. The objectives of the present study were to determine the effects of oral exposure to inorganic and organic forms of Se on the murine immune system and to compare the relative toxicity of the different chemical forms. Male BALB/c mice, 6–7 weeks of age, were exposed continuously to 0, 1, 3 or 9 ppm of Se as sodium selenite or seleno-L-methionine in the drinking water for 14 days. Following the treatment period mice were euthanized; trunk blood, spleen, thymus, liver and kidney were aseptically collected and organs weighed. Single-cell splenocyte cultures were made from the spleens and used to determine the effects of Se treatment on mitogen-induced lymphocyte blastogenesis and cytokine production. There were no changes in the 0 and 1 ppm Se groups as selenite. The thymus/body weight ratio was significantly reduced at 3 ppm Se as sodium selenite, and all other parameters remained unaffected. Exposure to 9 ppm of Se as sodium selenite resulted in marked decrease in body weight gain and relative organ weights. Treatment of mice with 9 ppm Se as sodium selenite increased erythrocyte counts in peripheral blood, reduced splenic cellularity, but increased the basal rate of splenocyte proliferation and induced a dose-dependent increase in phytohemagglutinin-P-induced lymphocyte proliferation. Sodium selenite at this dose increased the production of proinflammatory cytokines, tumor necrosis factor α and interleukin-1β, in lipopolysaccharide-stimulated splenic macrophages. Mice exposed to Se as seleno-L-methionine in the drinking water did not display any effects on the parameters examined at the dose range in this study. Results indicated that splenic macrophages and lymphocytes are sensitive to Se intoxication and there is a disparity in the immune system toxicity of inorganic and organic forms of Se administered via the drinking water, inorganic Se being more toxic.
A Role for Oxidative Stress in Suppressing Serum Immunoglobulin Levels in Lead-Exposed Fisher 344 Rats by N. Ercal; R. Neal; P. Treeratphan; P. M. Lutz; T. C. Hammond; P. A. Dennery; D. R. Spitz (pp. 251-256).
Evidence implicating oxidative stress in toxicity during lead intoxication in vivo has opened new avenues for investigation of the mechanisms of lead-induced immunosuppression. The current study explores the possibility that lead-induced oxidative stress contributes to the immunosuppression observed during lead poisoning. Fisher 344 rats were exposed to 2,000 ppm lead acetate in their drinking water for 5 weeks. One week following removal of lead from the drinking water, significant reductions in serum levels of IgA, IgM, and IgG were detected. Significant increases in oxidative damage, based on malondialdehyde (MDA) content, were observed in peripheral blood mononuclear cells (PMCs) collected during the same experiments. In addition, MDA content increased in livers from lead-exposed rats. Following 5 weeks of lead exposure, administration of either 5.5 mmol/kg N-acetylcysteine (NAC) or 1 mmol/kg meso-2,3-dimercaptosuccinic acid (DMSA) in the drinking water for 1 week significantly reversed the inhibitory effects of lead on serum immunoglobulin (Ig) levels. Also, all parameters indicative of oxidative stress returned to control levels. These results suggest that oxidative stress contributes to suppressed serum Ig levels during lead intoxication in vivo, and that intervention with either a thiol antioxidant (NAC) or a metal chelator (DMSA) will alleviate this lead-induced suppression by correcting the prooxidant/antioxidant imbalance caused by lead exposure.
The Effect of Sulfur Dioxide Inhalation on Visual Evoked Potentials, Antioxidant Status, and Lipid Peroxidation in Alloxan-Induced Diabetic Rats by A. Ağar; V. Küçükatay; P. Yargiçoğlu; B. Aktekin; S. Kipmen-Korgun; D. Gümüşlü; C. Apaydin (pp. 257-264).
The aim of the study was to investigate the effect of 10 ppm sulfur dioxide (SO2) exposure on visual evoked potentials (VEPs), thiobarbituric acid reactive substances (TBARS), and the activities of Cu,Zn superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in diabetes mellitus. Forty healthy male albino rats, aged 3 months, were divided into four equal groups: control (C), sulfur dioxide + control (CSO2), diabetic (D), and sulfur dioxide + diabetic (DSO2) groups. Experimental diabetes mellitus was induced by IV injection of alloxane monohydrate in a dose of 50 mg/kg body weight. Ten ppm sulfur dioxide was administered to the animals of sulfur dioxide–exposed groups in an exposure chamber for 1 h/day × 7 days/week × 6 weeks while control and diabetic groups were exposed to filtered air in the same condition.SO2 exposure, though markedly decreasing retina CAT and GSH-Px activities, significantly increased retina Cu,Zn-SOD activity in the diabetic and nondiabetic groups. In contrast to SO2-related increase in the activity of Cu,Zn-SOD, decrease in GSH-Px activity was observed in the brain of those groups. Brain CAT activity was unaltered. SO2 exposure caused the significant elevation in brain TBARS levels of CSO2 and DSO2 groups, whereas only in the retina TBARS level of the CSO2 group.SO2 exposure caused the significant prolongations of P1, N1, P2, and P3 components of VEPs in the nondiabetic and all components of VEPs in the diabetic groups. SO2 exposure also resulted in significant amplitude reductions in both experimental groups.
Comparison of Persistent Organic Pollutant Residues in Serum and Adipose Tissue in a Female Population in Belgium, 1996–1998 by A. Pauwels; A. Covaci; J. Weyler; L. Delbeke; M. Dhont; P. De Sutter; T. D'Hooghe; P. J. C. Schepens (pp. 265-270).
This study was performed to determine and compare persistent organic pollutant (POP) levels in different matrices in a female population. A total of 96 serum and 46 adipose tissue samples were collected from infertile women (n = 101) attending Centers for Reproductive Medicine in Belgium from 1996 to 1998. Gas chromatography with electron-capture detection was used to quantify residue levels on a lipid basis of seven organochlorine pesticides (OCPs) and seven polychlorinated biphenyls (PCBs). There was a strong association between adipose tissue and serum residues. The adipose tissue levels of CB-138, 153, 180 and p,p′-DDE were explained by the serum residues. Besides, the accumulation pattern for CB-153 and CB-180 in serum and adipose tissue are mirror images of each other.