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PubMed2002

Identical ring cleavage products during anaerobic degradation of naphthalene, 2-methylnaphthalene, and tetralin indicate a new metabolic pathway.

Anaerobic degradation of naphthalene, 2-methylnaphthalene, and tetralin (1,2,3,4-tetrahydronaphthalene) was investigated with a sulfate-reducing enrichment culture obtained from a contaminated aquifer. Degradation studies with tetralin revealed 5,6,7,8-tetrahydro-2-naphthoic acid as a major metabolite indicating activation by addition of a C(1) unit to tetralin, comparable to the formation of 2-naphthoic acid in anaerobic naphthalene degradation. The activation reaction was specific for the aromatic ring of tetralin; 1,2,3,4-tetrahydro-2-naphthoic acid was not detected. The reduced 2-naphthoic acid derivatives tetrahydro-, octahydro-, and decahydro-2-naphthoic acid were identified consistently in supernatants of cultures grown with either naphthalene, 2-methylnaphthalene, or tetralin. In addition, two common ring cleavage products were identified. Gas chromatography-mass spectrometry (GC-MS) and high-resolution GC-MS analyses revealed a compound with a cyclohexane ring and two carboxylic acid side chains as one of the first ring cleavage products. The elemental composition was C(11)H(16)O(4) (C(11)H(16)O(4)-diacid), indicating that all carbon atoms of the precursor 2-naphthoic acid structure were preserved in this ring cleavage product. According to the mass spectrum, the side chains could be either an acetic acid and a propenic acid, or a carboxy group and a butenic acid side chain. A further ring cleavage product was identified as 2-carboxycyclohexylacetic acid and was assumed to be formed by beta-oxidation of one of the side chains of the C(11)H(16)O(4)-diacid. Stable isotope-labeling growth experiments with either (13)C-labeled naphthalene, per-deuterated naphthalene-d(8), or a (13)C-bicarbonate-buffered medium showed that the ring cleavage products derived from the introduced carbon source naphthalene. The series of identified metabolites suggests that anaerobic degradation of naphthalenes proceeds via reduction of the aromatic ring system of 2-naphthoic acid to initiate ring cleavage in analogy to the benzoyl-coenzyme A pathway for monoaromatic hydrocarbons. Our findings provide strong indications that further degradation goes through saturated compounds with a cyclohexane ring structure and not through monoaromatic compounds. A metabolic pathway for anaerobic degradation of bicyclic aromatic hydrocarbons with 2-naphthoic acid as the central intermediate is proposed.

Anaerobiosis↗
PubMed2005

Web-type evolution of rhodococcus gene clusters associated with utilization of naphthalene.

Clusters of genes which include determinants for the catalytic subunits of naphthalene dioxygenase (narAa and narAb) were analyzed in naphthalene-degrading Rhodococcus strains. We demonstrated (i) that in the region analyzed homologous gene clusters are separated from each other by nonhomologous DNA, (ii) that there are various degrees of homology between related genes, and (iii) that nar genes are located on plasmids in strains NCIMB12038 and P400 and on a chromosome in P200. These observations suggest that genetic exchange and reshuffling of genetic modules, as well as vertical descent of the genetic information, were the main routes in the evolution of naphthalene degradation in Rhodococcus. These conclusions were supported by studies of transcription patterns in the region analyzed. It was found that the nar region is not organized into a single operon but there are several transcription units which differ in the strains investigated. The narA and narB genes were found to be transcribed as a single unit in all strains analyzed, and their transcription was induced by naphthalene. The putative aldolase gene (narC) was found on the same transcript only in strains P200 and P400. In NCIMB12038 transcription of two more gene clusters was induced by growth on naphthalene. Transcription start sites for narA and narB were found to be different in all of the strains studied. Putative regulatory genes (narR1 and narR2) were transcribed as a single mRNA in naphthalene-induced cells. At the same time, a number of the genes known to be essential for naphthalene catabolism in gram-negative bacteria were not found in the region analyzed.

Amino Acid Sequence↗
PubMed1998

A gene cluster encoding steps in conversion of naphthalene to gentisate in Pseudomonas sp. strain U2.

Pseudomonas sp. strain U2 was isolated from oil-contaminated soil in Venezuela by selective enrichment on naphthalene as the sole carbon source. The genes for naphthalene dioxygenase were cloned from the plasmid DNA of strain U2 on an 8.3-kb BamHI fragment. The genes for the naphthalene dioxygenase genes nagAa (for ferredoxin reductase), nagAb (for ferredoxin), and nagAc and nagAd (for the large and small subunits of dioxygenase, respectively) were located by Southern hybridizations and by nucleotide sequencing. The genes for nagB (for naphthalene cis-dihydrodiol dehydrogenase) and nagF (for salicylaldehyde dehydrogenase) were inferred from subclones by their biochemical activities. Between nagAa and nagAb were two open reading frames, homologs of which have also been identified in similar locations in two nitrotoluene-using strains (J. V. Parales, A. Kumar, R. E. Parales, and D. T. Gibson, Gene 181:57-61, 1996; W.-C. Suen, B. Haigler, and J. C. Spain, J. Bacteriol. 178:4926-4934, 1996) and a naphthalene-using strain (G. J. Zylstra, E. Kim, and A. K. Goyal, Genet. Eng. 19:257-269, 1997). Recombinant Escherichia coli strains with plasmids carrying this region were able to convert salicylate to gentisate, which was identified by a combination of gas chromatography-mass spectrometry and nuclear magnetic resonance. The first open reading frame, designated nagG, encodes a protein with characteristics of a Rieske-type iron-sulfur center homologous to the large subunits of dihydroxylating dioxygenases, and the second open reading frame, designated nagH, encodes a protein with limited homology to the small subunits of the same dioxygenases. Cloned together in E. coli, nagG, nagH, and nagAb, were able to convert salicylate (2-hydroxybenzoate) into gentisate (2,5-dihydroxybenzoate) and therefore encode a salicylate 5-hydroxylase activity. Single-gene knockouts of nagG, nagH, and nagAb demonstrated their functional roles in the formation of gentisate. It is proposed that NagG and NagH are structural subunits of salicylate 5-hydroxylase linked to an electron transport chain consisting of NagAb and NagAa, although E. coli appears to be able to partially substitute for the latter. This constitutes a novel mechanism for monohydroxylation of the aromatic ring. Salicylate hydroxylase and catechol 2,3-dioxygenase in strain U2 could not be detected either by enzyme assay or by Southern hybridization. However growth on both naphthalene and salicylate caused induction of gentisate 1,2-dioxygenase, confirming this route for salicylate catabolism in strain U2. Sequence comparisons suggest that the novel gene order nagAa-nagG-nagH-nagAb-nagAc-nagAd-++ +nagB-nagF represents the archetype for naphthalene strains which use the gentisate pathway rather than the meta cleavage pathway of catechol.

Base Sequence↗
PubMed1998

Naphthalene uptake by a Pseudomonas fluorescens isolate.

The uptake of naphthalene has been investigated in the metabolizing cells of Pseudomonas fluorescens utilizing [1-14C]naphthalene. The uptake displayed an affinity constant (Kt) of 11 microM and a maximal velocity (Vmax) of 17 nmol.h-1.mg-1 cellular dry weight. Naphthalene uptake was not observed in a mutant strain, TG-5, which was unable to utilize naphthalene as a sole source of carbon for growth. Uptake was significantly inhibited (approximately 90%) by the presence of growth-inhibiting levels of either azide or 2,4-dinitrophenol and was sensitive to the presence of structural analogues of naphthalene. The intracellular levels of ATP were not significantly reduced by the presence of either azide or 2,4-dinitrophenol. The presence of alpha-naphthol was found to noncompetitively inhibit naphthalene uptake, displaying a Ki of 0.041 microM. It is concluded that the first step in the utilization of naphthalene by Pseudomonas fluorescens is its transport into the cell by a specific energy-linked transport system.

2,4-Dinitrophenol↗
PubMed1991

Naphthalene-induced cataract in the rat. II. Contrasting effects of two aldose reductase inhibitors on glutathione and glutathione redox enzymes.

This investigation compared the effects of two types of aldose reductase inhibitors on several biochemical parameters in naphthalene-induced cataract of the rat over a time span of 102 days of treatment. Feeding of naphthalene daily to brown Norway rats resulted in gradual, progressive development of zonular opacities. As compared to control animals, the values of soluble protein, soluble glutathione (total of oxidized plus reduced) and activities of glutathione peroxidase and glutathione reductase were decreased in rats fed either naphthalene or naphthalene + FK366, a carboxylic-acid-type aldose reductase inhibitor. In marked contrast, treatment with A11576, a hydantoin-type aldose reductase inhibitor, maintained the values of most parameters (with one exception) at levels that were similar to those of the controls, and all lenses remained clear. A decline of glutathione was noted in all naphthalene-fed rats, irrespective of whether these animals had been treated with an aldose reductase inhibitor. The great decrease of glutathione with A11576 suggests that this inhibitor acts at some step in naphthalene metabolism following formation of naphthalene epoxide.

Aldehyde Reductase↗
PubMed1995

A mild progression type of naphthalene-induced cataract in brown-Norway rats.

Naphthalene-induced rat cataract is a useful experimental cataract--however, because of its short survival period, studies using this model have been for limited purposes. Based on the consideration that the short survival might be caused by systemic toxicity of an overdose of naphthalene administration (1 g/kg body weight every other day), the authors successfully established a naphthalene-induced cataract with mild progression in Brown-Norway rats. The naphthalene administration proposed is to initially administer 0.5 g/kg and after a 1-week interval 1 g/kg of 10% naphthalene once or twice a week through a stomach tube. While the type of lens opacification induced in the two groups administered once and twice a week, respectively, was the same as that seen by the previous administration method, the progression of lens opacification seen in the groups showed a dose-dependent increase. The survival rate in the rats given naphthalene every other day according to the old method was 50% at the 6th week and 0% at the 9th week. Survival of the two new groups was 70 and 60% at the 30th week, respectively. This new type of naphthalene-induced rat cataract should be a suitable model for long-term observations.

Animals↗
PubMedDate not supplied

[Comparative study of the plasmids controlling naphthalene biodegradation by a Pseudomonas culture].

The object of this work was to study 25 Pseudomonas strains growing in a medium with naphthalene as a sole carbon source. Naphthalene catabolism was controlled by conjugative plasmids in 14 strains. The molecular mass of the plasmids was rather big, from 60 to 130 MD. The plasmids were classified in terms of their incompatibility group were assigned to the P-7 and P-9 groups five to each group. The incompatibility group could not be determined in four plasmids. The character of naphthalene catabolism controlled by the plasmids implies that only two of the plasmids control naphthalene oxidation via the "ortho" pathway of catechol cleavage which is an intermediate product in the oxidation of naphthalene. Just as most of the so far known plasmids controlling naphthalene biodegradation, seven of the plasmids studied in this work controlled naphthalene oxidation via the "meta" pathway of catechol cleavage.

Biodegradation, Environmental↗
PubMed1983

Evidence for hepatic formation, export and covalent binding of reactive naphthalene metabolites in extrahepatic tissues in vivo.

Previous studies have shown that cytochrome P-450-mediated metabolism of naphthalene results in dose-dependent bronchiolar necrosis in mice and in the formation of reactive metabolites which deplete reduced glutathione and become bound covalently to tissue macromolecules. The finding that pulmonary glutathione levels were nearly totally depleted after large doses of naphthalene suggested that hepatic formation of reactive metabolites may contribute substantially to glutathione depletion and covalent binding in extrahepatic tissues. This possibility has been supported by several new lines of evidence: 1) similar levels of covalent binding were observed in lung, liver and kidney in vivo, yet the rate of kidney microsomal metabolic activation of naphthalene was much lower than in liver or lung; 2) phenobarbital pretreatment markedly increased in vivo covalent binding in lung, liver and kidney and increased hepatic but decreased pulmonary microsomal covalent binding; 3) 3-methylcholanthrene pretreatment resulted in slightly increased levels of covalent binding in lung, liver and kidney yet decreased pulmonary microsomal covalent binding; 4) administration of p-xylene, at doses which selectively decreased pulmonary microsomal metabolism of biphenyl (4-hydroxylation) and naphthalene (to reactive metabolites), decreased in vivo covalent binding in liver and kidney to the same extent as lung after [14C]naphthalene; and 5) pretreatment with buthionine sulfoximine preferentially depleted hepatic and renal but not pulmonary glutathione levels and markedly increased covalent binding in all three tissues. The severity of naphthalene-induced bronchiolar damage was unaffected by pretreatment with phenobarbital, 3-methylcholanthrene or p-xylene but was increased by prior administration of buthionine sulfoximine. These studies suggest that a portion of the reactive metabolites which deplete glutathione and bind covalently in extrahepatic tissues originate in the liver. Whether these circulating metabolites play a role in naphthalene-induced pulmonary bronchiolar damage is not clear.

Animals↗
PubMed2006

Sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by a charge-transfer process.

The photophysical properties of 4-naphthalen-1-yl-benzoic acid ligands and their Eu(III)-cored complexes were systematically investigated to elucidate the effective energy-transfer pathway in luminescent lanthanide complexes. A series of 4-naphthalen-1-yl-benzoic acid ligands, such as 4-naphthalen-1-yl-benzoic acid (NA-1), 4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzoic acid (NA-2), and 4-{4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzyloxy}-benzoic acid (NA-3), were synthesized and utilized for the synthesis of their Eu(III)-cored complexes, corresponding to NAC-1, NAC-2, and NAC-3. The fluorescence spectra of NA-1 and NA-2 show large Stokes shifts with increasing solvent polarity. These large Stokes shifts might be dominantly due to the formation of an intramolecular charge transfer (ICT) complex in the excited state. Also, the intensive luminescence of the Eu(III) ions by the photoexcitation of the ligand in NAC-1 and NAC-2 in polar solvents supports that the energy transfer from the ligand to the Eu(III) ion takes place efficiently. In the case of NA-3, which has a -CH2OPh- group that acts as a blocking group, there is no dependence of the fluorescence spectrum on the solvent nature and no luminescence of the Eu(III) ions by the photoexcitation of the ligand, indicating no formation of the ICT state. This can be due to the fact that the formation of the ICT state in NA-3 was prevented because the -OCH2- group acts as a blocking group by interrupting the pi-conjugation between the benzoic acid and the naphthalene unit. From these photophysical studies, we suggest that the ICT state plays a very important role in the energy-transfer pathway from the ligand to the Eu(III) ion. To our best knowledge, this is the first demonstration of sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by the charge-transfer process.

Journal Article↗
PubMed2005

Synthesis and antifungal activity of naphthalene-1,4-diones modified at positions 2, 3, and 5.

A series of 2-arylamino-5-hydroxy-naphthalene-1,4-diones, 3-arylamino-5-methoxy-naphthalene-1,4-diones, and 2-arylamino-3chloro-5-hydroxy-naphthalene-1,4-diones were synthesized and tested for in vitro antifungal activity against the species Candida and Aspergillus niger. Among those tested, 3-arylamino-5-methoxy-naphthalene-1,4-diones exhibited potent antifungal activity. In general, the 3-arylamino-5-methoxy-naphthalene-1,4-diones showed more potent antifungal activity than the 2-arylamino-5-hydroxy-naphthalene-1,4-diones and the 2-arylamino-3-chloro-5-hydroxy-naphthalene-1,4-diones.

Antifungal Agents↗
PubMed2002

6-Substituted 3,4-dihydro-naphthalene-2-carboxylic acids: synthesis and structure-activity studies in a novel class of human 5alpha reductase inhibitors.

Novel 3,4-dihydro-naphthalene-2-carboxylic acids were synthesized and evaluated for 5alpha reductase inhibitory activity. This enzyme exists in two isoforms and is a pharmacological target for the treatment of benign prostatic hyperplasia, male pattern baldness and acne. In the present study non-steroidal compounds capable of mimicking the transition state of the steroidal substrates were prepared. The synthetic strategy for the preparation of compounds 1-6 consisted of triflation followed by subsequent Heck-type carboxylation or methoxy carbonylation for 6-phenyl-3,4-dihydronaphthalen-2(1H)-one 1c. A Negishi-type coupling reaction between 6-(trifluoro-methanesulfonyloxy)-3,4-dihydro-naphthalene-2-carboxylic acid methyl ester 7b and various aryl bromides led, after further transformations, to 6-substituted 3,4-dihydro-naphthalene-2-carboxylic acids 7-15. In a similar way the corresponding naphthalene-2-carboxylic acids 16 and 17 were obtained. The DU 145 cell line and prostate homogenates served as enzyme sources for the human type 1 and type 2 isozymes, whereas ventral prostate was employed to evaluate rat isozyme inhibitory potency. The most active inhibitors identified in this study were 6-[4-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (3) (IC50 = 0.09 microM, rat type 1), 6-[3-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (13) (IC50 = 0.75 microM, human type 2; IC50 = 0.81 microM, human type 1) and 6-[4-(N,N-diisopropylamino-carbonyl)phenyl]naphthalene-2-carboxylic acid (16) (IC50 = 0.2 microM, human type 2). The latter compound was shown to deactivate the enzyme in an uncompetitive manner (Ki = 90 nM; Km, Testosterone = 0.8-1.0 microM) similar to the steroidal inhibitor Epristeride. Select inhibitors (13 and 16) were tested in vivo using testosterone propionate-treated, juvenile, orchiectomized SD-rats. None of the compounds was active at a dose of 25 mg/kg. This result might in part be ascribed to the relatively poor in vitro rat isozyme inhibitory potency.

5-alpha Reductase Inhibitors↗
PubMed1996

Bacterial Growth on Distant Naphthalene Diffusing through Water, Air, and Water-Saturated and Nonsaturated Porous Media.

The influence of substrate diffusion on bacterial growth was investigated. Crystalline naphthalene was supplied as the substrate at various distances in the range of centimeters from naphthalene-degrading organisms separated from the substrate by agar-solidified mineral medium. Within 2 weeks, the cells grew to final numbers which were negatively correlated with the distance from the substrate. A mathematical model that combined (i) Monod growth kinetics extended by a term for culture maintenance and (ii) substrate diffusion could explain the observed growth curves. The model could also predict growth on naphthalene that was separated from the bacteria by air. In addition, the bacteria were grown on distant naphthalene that had to diffuse to the cells through water-saturated and unsaturated porous media. The growth of the bacteria could be used to calculate the effective diffusivity of naphthalene in the three-phase system. Diffusion of naphthalene in the pore space containing 80% air was roughly 1 order of magnitude faster than in medium containing only 20% air because of the high Henry's law coefficient of naphthalene. It is proposed that the effective diffusivities of the substrates and the spatial distribution of substrates and bacteria are the main determinants of final cell numbers and, consequently, final degradation rates.

Journal Article↗
PubMedDate not supplied

[Fatty acid composition of blood plasma of rabbits treated with naphthalene oil].

Native naphthalene oil was used for skin applications in 100 rabbits, resin-free naphthalene oil was used for skin applications in 30 rabbits and 50 animals were administered with resin-free naphthalene per os. Quantitative and qualitative alterations of individual fatty acids were estimated in rabbit blood plasma before and after these naphthalene treatments. Distinct decrease in content of lauric, myristic, pentadecanoic, palmitic, margarinic and stearic acids as well as increase of oleic, linoleic and arachidonic acids were observed after the treatment course consisting of 10 naphthalene procedures. The ratio of unsaturated/saturated fatty acids was increased after all the naphthalene treatments. The data obtained suggest that naphthalene therapy may be used in health resort treatment of some disorders related to impairment of lipid metabolism.

Alkanes↗
PubMed2005

Regiospecific oxidation of naphthalene and fluorene by toluene monooxygenases and engineered toluene 4-monooxygenases of Pseudomonas mendocina KR1.

The regiospecific oxidation of the polycyclic aromatic hydrocarbons naphthalene and fluorene was examined with Escherichia coli strains expressing wildtype toluene 4-monooxygenase (T4MO) from Pseudomonas mendocina KR1, toluene para-monooxygenase (TpMO) from Ralstonia pickettii PKO1, toluene ortho-monooxygenase (TOM) from Burkholderia cepacia G4, and toluene/ortho-xylene monooxygenase (ToMO) from P. stutzeri OX1. T4MO oxidized toluene (12.1+/-0.8 nmol/min/mg protein at 109 microM), naphthalene (7.7+/-1.5 nmol/min/mg protein at 5 mM), and fluorene (0.68+/-0.04 nmol/min/mg protein at 0.2 mM) faster than the other wildtype enzymes (2-22-fold) and produced a mixture of 1-naphthol (52%) and 2-naphthol (48%) from naphthalene, which was successively transformed to a mixture of 2,3-, 2,7-, 1,7-, and 2,6-dihydroxynaphthalenes (7%, 10%, 20%, and 63%, respectively). TOM and ToMO made 1,7-dihydroxynaphthalene from 1-naphthol, and ToMO made a mixture of 2,3-, 2,6-, 2,7-, and 1,7-dihydroxynaphthalene (26%, 22%, 1%, and 44%, respectively) from 2-naphthol. TOM had no activity on 2-naphthol, and T4MO had no activity on 1-naphthol. To take advantage of the high activity of wildtype T4MO but to increase its regiospecificity on naphthalene, seven engineered enzymes containing mutations in T4MO alpha hydroxylase TmoA were examined; the selectivity for 2-naphthol by T4MO I100A, I100S, and I100G was enhanced to 88-95%, and the selectivity for 1-naphthol was enhanced to 87% and 99% by T4MO I100L and G103S/A107G, respectively, while high oxidation rates were maintained except for G103S/A107G. Therefore, the regiospecificity for naphthalene oxidation was altered to practically pure 1-naphthol or 2-naphthol. All four wildtype monooxygenases were able to oxidize fluorene to different monohydroxylated products; T4MO oxidized fluorene successively to 3-hydroxyfluorene and 3,6-dihydroxyfluorene, which was confirmed by gas chromatography-mass spectrometry and 1H nuclear magnetic resonance analysis. TOM and its variant TomA3 V106A oxidize fluorene to a mixture of 1-, 2-, 3-, and 4-hydroxyfluorene. This is the first report of using enzymes to synthesize 1-, 3-, and 4-hydroxyfluorene, and 3,6-dihydroxyfluorene from fluorene as well as 2-naphthol and 2,6-dihydroxynaphthalene from naphthalene.

Biodegradation, Environmental↗
PubMed2004

Platinum complexes of naphthalene-1,8-dichalcogen and related polyaromatic hydrocarbon ligands.

Platinum bisphosphine complexes bearing dichalcogen-derivatised naphthalene, acenaphthene or phenanthrene ligands have been prepared by either oxidative addition to zero-valent platinum species or from [PtCl(2)(PPhR(2))] (R=Ph or Me) and the disodium or dilithium salts of the parent disulfur, diselenide or mixed S/Se species. The parent naphthalene, acenaphthene and phenanthrene chalcogen compounds were treated with either [Pt(PPh(3))(4)] or [Pt(C(2)H(4))(PMe(3))(2)] (prepared in situ from [PtCl(2)(PMe(3))(2)], ethene and sodium naphthalide or super hydride [LiBEt(3)H]) to give the appropriate platinum(II) species. The dilithium salts of 1,8-E(2)-naphthalene (E=S or Se) prepared in situ by reduction of the E-E bond with [LiBEt(3)H] were treated with [PtCl(2)(PPh(3))(2)] to give [Pt(1,8-E(2)-nap)(PPh(3))(2)]. The tetraoxides [Pt(1,8-(S(O)(2))(2)-nap)(PR(3))(2)] (PR(3)=PPh(3) or PMe(2)Ph) were prepared in a similar metathetical manner from the appropriate [PtCl(2)(PR(3))] complexes and the disodium salt of naphthalene 1,8-disulfinic acid (1,8-(S(O)ONa)(2)-nap). The X-ray structures of selected examples reveal bidentate coordination with the naphthalene-E(2) unit hinged (111-137 degrees) with respect to the coordination plane. The naphthalene ring suffers significant distortion from planarity.

Ligands↗
PubMed1995

Naphthalene-induced atresia in the ovary of the crayfish, Procambarus clarkii.

Female crayfish, Procambarus clarkii, were exposed to 10 ppm naphthalene to determine its effect on ovarian development. Ovaries were removed for examination after 1, 2, 4, 6, 8, 10, 12, and 15 days of exposure to the naphthalene. Crayfish that had been exposed to naphthalene for 15 days were then returned to clean freshwater for 1, 2, 4, 5, 7, 10, and 15 days to determine whether the ovaries would recover from the naphthalene exposure. The ovarian index, which reflects the weight of the ovary, decreased gradually over the 15-day naphthalene exposure period. The previtellogenic and vitellogenic oocytes degenerated. Intense atresia along with yolk resorption led to this decrease in the ovarian index. In contrast, the ovaries of the control crayfish developed into ripe gonads. However, immature oocytes reappeared in the ovaries of the crayfish subjected to depuration, which suggests that the ovary of P. clarkii can recover from naphthalene-induced atresia.

Animals↗
PubMed1990

Identification of metabolites from degradation of naphthalene by a Mycobacterium sp.

A Mycobacterium sp. isolated from oil-contaminated sediments was previously shown to mineralize 55% of the added naphthalene to carbon dioxide after 7 days of incubation. In this paper, we report the initial steps of the degradation of naphthalene by a Mycobacterium sp. as determined by isolation of metabolites and incorporation of oxygen from 18O2 into the metabolites. The results indicate that naphthalene is initially converted to cis- and trans-1,2-dihydroxy-1,2-dihydronaphthalene by dioxygenase and monooxygenase catalyzed reactions, respectively. The ratio of the cis to trans-naphthalene dihydrodiol isomers was approximately 25: 1. Thin layer and high pressure liquid chromatographic and mass spectrometric techniques indicated that besides the cis- and trans-1,2-dihydroxy-1,2-dihydronaphthalene, minor amounts of ring cleavage products salicylate and catechol were also formed. Thus the formation of both cis and trans-naphthalene dihydrodiols by the Mycobacterium sp. is unique. The down-stream reactions to ring cleavage products proceed through analogous dioxygenase reactions previously reported for the bacterial degradation of naphthalene.

Biodegradation, Environmental↗
PubMed2006

Protozoan grazing increases mineralization of naphthalene in marine sediment.

Bacterial decomposition of organic matter is frequently enhanced when protozoa are present. Various mechanisms have been proposed to account for this phenomenon, including effects associated with grazing by protozoa (such as increased recycling of limiting nutrients, removal of senescent cells, or reduction of competition among bacteria) and indirect effects of grazers (such as excretion of bacterial growth factors). Few studies have examined the role of protozoa in bacterial degradation of xenobiotic compounds in sediment containing a natural community of microbes. The effect of protozoa on mineralization of naphthalene was investigated in this study. Laboratory experiments were conducted using field-contaminated estuarine sediment, with the indigenous microbial populations. Mineralization of naphthalene was up to four times greater in treatments with actively grazing protozoa than in treatments containing the grazing inhibitor cytochalasin B. Control experiments confirmed that the grazing inhibitor was not toxic to ciliates but did prevent them from grazing. The grazing inhibitor did not affect growth rates of a mixed culture of sediment bacteria or a pure polycyclic-aromatic-hydrocarbon-degrading strain. Once grazing had been inhibited, supplementing treatments with inorganic N and P, glucose, or additional protozoa failed to stimulate naphthalene mineralization. Naphthalene-degrading bacteria were four to nine times less abundant when protozoan grazing was suppressed. We suggest that protozoa enhance naphthalene mineralization by selectively grazing on those sediment bacteria that ordinarily would outcompete naphthalene-degrading bacteria.

Animals↗