Metabolism of aromatic hydrocarbons in marine organisms

Levels, spatial distributions, and provision of petroleum hydrocarbons and phthalates in sediments from Obhur lagoon, Red Sea coast of Saudi Arabia

The levels, spatial distribution, and sources of petroleum hydrocarbons and phthalates were assessed in surface sediment samples from the urban lagoon of Obhur near Jeddah, the largest city on the Red Sea coast of Saudi Arabia. The lagoon was divided into the inner zone, middle zone, and outer zone based on its geomorphological features and developmental activities. n-Alkanes, hopane and sterane biomarkers, and unresolved complex mixture were the major petroleum hydrocarbon compounds of the total extractable organic matter. Phthalates were also measured in the sediment samples. In the three zones, n-alkanes ranged from 89.3 ± 88.5 to 103.2 ± 114.9 ng/g, whereas the hopane and sterane biomarkers varied from 69.4 ± 75.3 to 77.7 ± 69.9 ng/g and 72.5 ± 77.9-89.5 ± 82.2 ng/g, respectively. The UCM concentrations ranged from 821 ± 1119 to 1297 ± 1684 ng/g and phthalates from 37.4 ± 34.5 65 ± 68 ng/g. The primary origins of these anthropogenic hydrocarbons in the lagoon sediments were petroleum products (boat engine discharges, boat washing, lubricants, and wastewater flows) and plasticizers (plastic waste and litter). The proportions of anthropogenic hydrocarbons derived from petroleum products in the sediment's TEOM ranged from 43 ± 33 to 62 ± 15%, while the percentages for plasticizers varied from 2.9 ± 1.2 to 4.0 ± 1.6%. The presence and inputs of these contaminants from petroleum and plastic wastes in the lagoon's sediments will eventually have an impact on its habitats, including the benthic nursery and spawning areas.

Urinary metabolites of dodecylcyclohexane in Salmo gairdneri: evidence of aromatization and taurine conjugation in trout

1. The urinary metabolites of 3H-dodecylcyclohexane were investigated in rainbow trout, Salmo gairdneri R. after a single intragastric dose. In 72 h, 14% of the ingested radioactivity was excreted in urine. 2. Cyclohexylacetic acid, 1-hydroxy-, 3-hydroxy- and 4-hydroxy-cyclohexylacetic acids were present in the unconjugated fraction. 3. In the glucuronide fraction (1.2% dose) labelled aglycones were cyclohexylacetic acid and phenylacetic acid. 4. More than 30% of the urinary 3H was present as phenylacetic and cyclohexylacetic acids conjugated with taurine.

The glutathione S-transferases of fish

Substantial soluble glutathione S-transferase activity and millimolar reduced glutathione (GSH) are present in most tissues of both teleosts and elasmobranchs. The hepatic enzymes of fish conjugate a range of electrophilic substrates with GSH, although their specificities are less broad than those of the transferases in rodent liver. There is no good evidence that fish transferases have ligandin-like activity or a 'suicide' function. All fish livers tested have several transferase isoenzymes. They are dimers of subunits whose Mrs are about 25 kDa and which may have different catalytic properties. In some species transferase activity is induced by agents such as phenols or 3-methylcholanthrene. Glutathione S-transferases are important detoxication enzymes in fish.

Effect of environmental temperature on naphthalene metabolism by juvenile starry flounder (Platichthys stellatus)

Juvenile starry flounder (Platichthys stellatus) maintained at 4 degrees or 12 degrees C were forced-fed 3H-1-naphthalene. At 24 hr, after the initiation of exposure, significantly (p less than 0.05) higher concentrations (2 to 15 times) of naphthalene were present in tissues of starry flounder at 4 degrees C than those present in fish held at 12 degrees C. The influence of lowering of water temperature on naphthalene retention was even more marked after one week. At this time, muscle and liver of fish at 4 degrees C contained 26 and 34 times, respectively, more naphthalene than did muscle and liver of fish at 12 degrees C. Concentrations of total metabolites, in most tissues were not substantially higher at the lower temperature either 24 or 168 hr after the naphthalene-exposure. Thin-layer chromatographic separation of the metabolites revealed that at 24 hr, 1,2-dihydro-1,2-dihydroxynaphthalene (dihydrodiol) was the major component in liver (40 to 50% of extracted metabolites) and muscle (approximately 80% of extracted metabolites) regardless of the temperature. Bile contained, primarily conjugates (e.g., glucuronides), which yielded the dihydrodiol as the principal metabolite on enzymatic hydrolysis. From 24 to 168 hr, the concentrations of each metabolite class did not vary directly with the concentrations of total metabolites. Accordingly, at 168 hr, the ratio of total metabolite concentrations in liver of fish at 4 degrees C compared to 12 degrees C was 1.6, whereas the ratios for the dihydrodiol, sulfate/glucoside conjugates and glucuronide conjugates were 4.5, 0.6 and 3.8 respectively. Generally, lowered water temperature increased tissue concentrations of the parent hydrocarbon and its metabolites. However, the magnitude of the increase was dependent upon the compound, the tissue, and the time after the initiation of the exposure. The results emphasize the importance of determining concentrations of individual metabolites together with parent hydrocarbons in tissues of fish when assessing effects of environmental parameters on xenobiotic toxicity.

Mono-oxygenase activities of coho salmon (Oncorhynchus kisutch) liver microsomes using three polycyclic aromatic hydrocarbon substrates

1. Benzo[a]pyrene, 2,6-dimethylnaphthalene, and naphthalene were used as substrates for a coho salmon (Oncorhynchus kisutch) liver microsomal preparation. 2. The apparent Michaelis constants (Km) were as follows: benzo[a]pyrene, 2.1 microM; 2,6-dimethylnaphthalene, 15.3 microM; and naphthalene, 300 microM. 3. The results indicate that the microsomal preparation had a high affinity for 2,6-dimethylnaphthalene. Thus, 2,6-dimethylnaphthalene, an important constituent of petroleum products, is a useful substrate for research on the disposition in vivo and in vitro of xenobiotics introduced into marine environments by petroleum pollution.

The disposition of aromatic hydrocarbons in adult spot shrimp (Pandalus platyceros) and the formation of metabolites of naphthalene in adult and larval spot shrimp

1. Adult spot shrimp (Pandalus platyceros) exposed to 110 p.p.b. (microgram/ml) of the water-soluble fraction of Prudhoe Bay crude oil for one week accumulated a variety of low-molecular weight aromatic hydrocarbons (primarily C1-C5 substituted derivatives) in thoracic and abdominal tissues. 2. Adult and larval spot shrimp were exposed to 3H- and 14C- labelled naphthalene (a component of the water-soluble fraction) in seawater to delineate the types of metabolites formed. Both adults and larvae converted naphthalene to conjugated and non-conjugated structures such as the glucuronide, sulphate, dihydrodiol and phenolic derivatives. The presence of a quinone was also indicated.

Multiple forms of inducible drug-metabolizing enzymes: a reasonable mechanism by which any organism can cope with adversity

All organisms possess a number of genetically regulated mechanisms in order to cope with rapid adverse changes in the environment. The two systems which appear to respond to a seemingly endless array of chemical specificities are the immune response and the induction of drug-metabolizing enzymes. Similarities and differences between the immunoglobulin and the cytochrome P-450-mediated monooxygenase systems are described. DNA insertion sequences, plasmid "transposons," maize "controlling elements," gene duplication, intervening sequences, and high-frequency intergenic recombination are all discussed as possible methods by which organisms can "adapt" quickly to a new selective pressure. If the regulation of P-450 induction resembles in any way the other methods by which pro- and eukaryotes cope genetically with numerous forms of environmental adversity, therefore, it is very likely that mammalian tissues contain hundreds, if not thousands, of inducible forms of P-450.

Crankcase oils: are they a major mutagenic burden in the aquatic environment?

Fractions from used crankcase oil enriched in polyaromatic hydrocarbons induced revertant colonies in Salmonella typhimurium strain TA 98 when activated by rat or trout liver extracts. The mutagenic activity was not due to benzopyrene or benzanthracene. Fractions from various crude and refined petroleums were nonmutagenic. Among various petroleum hydrocarbons entering inland and coastal waters, used crankcase oils may represent a major mutagenic burden.