Document jmBkbRav1xRBJ9KXR9NGygGzp

Nature Vol. 251 September 20 1974 219 by rats, rabbits and pigeons1"'. All the compounds investi gated have two unsubstituted carbon atoms in ortho positions to each other. It has been suggested that this substitution pattern is required for the metabolic break down of chlorobiphenyls*. A thorough investigation of the chlorobiphcnyl residues found in man and in higher aninruls partly confirms this suggestion'. Hutzinger ct aid have investigated the fate of a chloro- biphenyl containing only isolated, unsubstiluled carbon atoms--2,2',4,4',5,5'-hexachlorobiphcnyl--in rats, pigeons and trout. No hydroxy-containing metabolites weTC detected in the excreta by the methods used. This chlorobi phcnyl is one of the major components in technical PCB with chlorine contents above 50%. Furthermore, it is found in relatively high amounts in all species investigated including man7. Fig. I Photography of a polar bear ((,'mh maritimus) and three cubs on tundra. u, Normal black and while phot, v aph in the visible portion of the electromagnetic spulrum (Kodak DoubleX Acrographic 2405 film, Hasselbiad 150 mm Snnnar lens, f/16, 1/500 Si. b. Ultraviolet photo graph (Kodak Acrographic Double X 2405 film, Hasselbiad 105 mm UV-Sonnai lens, Kodak 18A filler, f/5.6, 1/500 s). It has been shown, however, that rabbits given 1,2,3-, 1,2,4- or 1,3,5-trichlorobenzene always excreted chlo rinated monophenols. The yields over 5 d were 78, 42 and 5%, respectively*. ' The fact that even 1,3,5-trichlorobenzene (containing only isolated unsubstituted carbon atoms) is hydroxyiated, led us to reinvestigate the behaviour of 2,2',4,4',5,5'- This observation of `black' polar bears seems to have further implications. At present, the biological significance of white coat coloration in animals is not clear. Whiteness in arctic climates obviously provides camouflage for many birds and mammals. Theoretical analjsis and quantitative measurements suggest that some white pelts transfer solar energy more efficiently to the skin than dark pelts'*. Thus white coloration may also play an important role in thermoregulation for a number of species including the white-coated pups of the harp seal (Pcgophilus groenlandici/i-y. The older view that dark pelts absorb solar radiation while white pells reflect it and thus reduce radiation ab sorption* is probably incorrect. Regardless, the fact that hexachlorobiphenyl in some animal species. Rats were given the chlorobiphenyl' in peanut oil (20 mg ml"') and an amount corresponding to about 15 mg was consumed during the night by each animal. Faeces were collected daily, dried and extracted with ether (Soxhlet extraction), The extracts were divided into two parts, one of which was treated with diazomethane. After evaporation of solvent the residue was dissolved in hexane and shaken with sulphuric acid before analysis by gas chromatography using an electron capture detector'. The acid treatment removes most unwanted extractives but docs not affect chlorobiphenyls and methoxy-chlorohiphenyls. some white pelts ahsorb ultraviolet radiation while others, such as the arctic hare reflect it', suggests that any dis cussion of "life's color code"* is incomplete without Cl Cl further consideration of the near ultraviolet component in solar radiation. We thank Drs 1. Stirling, C. Jonkel. and K. Ronald for Cl their support. D. M. Lavione N. A. 0R1TSLAND Cl Department of Zoology. College of Biological Science, I R = CH, University of Guelph, III It = 11 Guelph, Ontario, Canada Fig. 1 Alternative structures I and II of the methylated metabolite of 2.2'.4,4',5,5'-hcxachlorobiphenyl in rats Received June 3, 1974. and mice. The suggested cyclisation reaction (see text) of II 1 Brooks. J. W., in Bears--their biology and management (edit, upon electron impact in the mass spectrometer is indicated. l by Herrcro, S.), 138-141 (lUCSl, Morgcs, Switzerland, 1972). ' Lavigne, D. M., and 0ritlland, N. A.. Can. J. Zool. (in the In addition to unchanged hcxachlorobiphenyl a new compound was found in the methylated extract after 2 d. press). When analysed by combined gas chromatography-mass ' Kovnrik, M,, Nature. 201, 1085 (1964). spectrometry (quadropolc instrument) this substance * 0ritsland, N. A., Camp. Biochem. Physiol., 40A, 359 (1971). * 0ritsland, N. A , and Ronald, K.. Comp, Biocliem. Physiol., 44A, 519 (1973). showed a molecular ion at 388 mass units (m.u.) (6 Cl) corresponding to a melhoxyhexachlorobiphenyl. The struc * Hamilton. \V. J. Ill, Life's color code, 49-67 (McGraw-Hill, ture of this compound (Fig. 1), obviously derived from a New York. 1973). phenolic metabolite of 2,2',4,4',5.5'-hexachlorobiphenyl, must be I or II provided no migrations of chlorine atoms have taken place. Mass spectral studies performed in this laboratory using Metabolic hydroxylation of a chlorobiphcnyl about 35 synthetic methoxychlorobiphenvIs (S. J. and G S , unpublished) have shown that compounds containing a containing only isolated unsubstituted positions--2,2',4,4r,5,5'> bexachlorobiphenyl methoxy group in the two position, 11, for example, readily lose CH-.Cl (50 m.u.) upon electron impact. Th-.s results in very abundant peaks in the range 83-234% of Recent investigations on the metabolism of chloro- the molecular ion at M*-50 m.u. which can be explained biphenyls of known structure have shown that compounds containing four chlorine atoms or less arc hydroxylated hy the formation of cyclic structures (Fig. 1). Similar fragmentation patterns have previously bcv.ii 1M)(W mnmmlunr 1 ft*awffryv: yf e y p i OSH 0 2 5 9 9 0 f ! STLCOPCB4009952 . -F . --X - n uA ait** (: 220 Nature Vol. 25/ September 20 /VV Control .experiments showed that bacterial action during ;V): the drying of the faeces was not rcspon-ihlc for the nydroxylalion. VJ Mice given the hexachlorohipheny I also ewreted III iGLC) in the faeces. When the substance u.ic given tu quails (about II mg per animal) no metabolite Jould be detected in the excreta. It was. however, found that large 3-1. amount', of unchanged chlorobiphcnyl were excreted in ii; both faeces and eggs--about 9 and 33',.. rr-pCctiv eh. during 10 d. ' FIr. Z Part of the mass spectrum of [tie methylated meta bolite. The results presented here show that a chlerohiphenyl containing only isolated unsubstiluted pusilior, can be rr.etaboliseif by mammals albeit at a lower tale than chlorobipheny Is containing vicinal hydrogen atoms. I: seems, therefore, that most of the high chlorinated com pounds in PCB can be excreted not only uncb.aneed but also as metabolites The latter route implies that the chlorobipheny Is are not further circulated in the environ ment but that new compounds are released the persistence and toxicity of which are not sufficiently known. This work was supported by the Nadeau. Sardim Environment Protection Board. We thank Drs I. kihi,trom and J. Ohrborg supplying the excreta from the mice and Dr C. A. Wachtmeister for discussions. M..<v spectra were run by Dr B. Jansson. S. Jtssts observed in the mas.i spectra of 2-methoxychlorodiphenyl National Swedish Environment Protection Board. ethers'*". ' Special Analytical Laboratory ' Tiie loss of CH.Cl in the mass spectra of all .1- or 4methoxychlorobiphenyl, investigated so far have on the Environmental Toxicology Unit, G. St vos i ltd si other hand, never exceeded 30"o of the molecular ion. The Section of Organic Chemistry. mass spectrum of the methyl ether of the present metabolite I! a'J.cnberg Laboratory. (Fig. 2) shows a peak at M'-50 m u. which is only 13% of L niwrsity of Stockholm, the molecular ion. This fragmentation strongly favours S-l',4 OS Stockholm 50 structure III of the original phenol. Final proof for the structure, however, must await comparison with synthetic Received April g; revised June 7, 1974. & materia! of known structure. The elimination rate of unchanged hexachlorobiphenyl ' B.uck. W. D.. and Cornish. H. H.. J. biol Chem ;t4 ''-01 3302 (1959). '' and the metabolite (assuming equal detector response on - Hutonger. O., Nash. D. M.. Safe, S.. DcEreita-. A. S W & GLC) is shown in t ig. 3 The total amount of metabolite excreted during 7 d was calculated to be about 1.3% of the dose. The corresponding figure for unchanged biphenyl No: stroni. R. 3.. Wildish, D. J.. and Zitko. V. x j-ft 312 314 (1972). 5 oshimura. H.. and Yamamoto, H.. Chcm. pirn,-. lb, I 21. 1168-1169 (1973). was about 7%. No trace of III or conjugates thereof were ' Yoxhimura. H.. Yamamoto. H.. and Saeki S. C, ,.-rm found in the urine. Our experiments do not discriminate between micro somal or microbial hydroxylation of the chlorobiphcnyl Hull.. 21, 2231 22)6 (1973). ' Gardner, A. M.. Chen. J. T,, Roach. ). A. Cl.. rJ Rueeffi. E. P.. Ilioehein. hiophvx. Hex. Ctmtmtm.. 55. I '*77-1)84 (1973). as no bile cnnnulaiion experiments have been performed. ` S'.Suite, F... and Acker. (.., Nttturw ixseexelinften. 61. 79 (]974> Hut the presence of the metabolite in the faeces--and not Jensen. S.. and Sundstuini G., Anti,it/ 3, 70 76 f]'-"4i. & f in the urine--is in accordance with the results of other investigations concerning the metabolism of PCB in rats' *. ' Jondorf, W. R.. Parke. D. V., and Williams, R T.. Bun-hem. J.. 61. 512 -521 (1955). ` Monm, M.. Sundstrdm. G., and Wachtmeister. C. A.. Ana t hem. wit/.. 27, 3121 3122 (19731. Jensen. S.. and Renherg, I... Ainhio. t, 62 65 !19"2'. 6 Rappe. C., and Nilsson r .a i ...... *> '.m-'U' 19721 & ________ DSW 025991 . Sexual maturation of Japanese eel and production of eel larvae in the aquarium Tut- iife history of Ihc eel is complex and despite many insesu- gatipns little is known about its embryonic development. Some investigators such as Grassi and Calandrtccio (I >96 cited in ref. I) and Fish1, described the supposed cat.y develop ment of cels, using developing eggs collected by a trawl for young fish in suspected spawning grounds of cels. The time ot fertilisation of these eggs, however, was unknown, and the species involved was uncertain. Artificial maturation ol eel- n hormonal treatment is another approach which has been attempted by many workers5'*. They all. however, failevl to ffVl Fig- .1 Excretion rate ifaecesl of 2.2,4,4',5,5' hexachloiobi- phenyl ( -- i and its metabolite (--------) from a rat as htsachlorobipheny 1 ingested. obtain mature eggs and sperm and thus to clarify the en'.brs on'C development of eels. Here wc describe the first success with tb.o approach. ' 'S>_ STLCOPCB4009953