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DIBROMOACETIC ACID, A PREVALENT BY-PRODUCT OF DRINKING WATER DISINFECTION, COMPROMISES THE SYNTHESIS OF SPECIFIC SEMINFEROUS TUBULE PROTEINS FOLLOWING BOTH IN VIVO AND IN VITRO EXPOSURES
Citation:
Holmes, M., J D. Suarez, N L. Roberts, M L. Mole, A S. Murr, AND G R. Klinefelter. DIBROMOACETIC ACID, A PREVALENT BY-PRODUCT OF DRINKING WATER DISINFECTION, COMPROMISES THE SYNTHESIS OF SPECIFIC SEMINFEROUS TUBULE PROTEINS FOLLOWING BOTH IN VIVO AND IN VITRO EXPOSURES. JOURNAL OF ANDROLOGY 22(5):878-890, (2001).
Description:
ABSTRACT
Dibromoacetic acid(DBA) is a byproduct of drinking water disinfection that alters spermatogenesis in adult male rats. To identify a mechanism by which DBA alters spermatogenesis, seminiferous tubules representing specific groups of spermatogenic stages were exposed either in vivo or in vitro and structural and functional consequences were evaluated. Seminiferous tubules representing stages I-V, VI-VIII, and IX-XIV were isolated from testes of adult rats and cultured overnight under conditions of reduced oxygen and temperature. For in vivo exposures, seminiferous tubules were recovered from animals which received 250 mg/kg DBA via gavage for 5 days. For in vitro exposures, 180 and 600 M concentrations were tested; these concentrations bracket the concentration of DBA observed within the testis following in vivo exposure. Protein synthesis was evaluated by 35S-methionine labeling overnight and quantitative analysis of radiolabeled proteins in mini, two dimensional (2D) SDS-PAGE gels. Radioinert cultures were processed for light and electron microscopy. Morphological evaluation indicated that all spermatogenic stages of the seminiferous tubules from control animals were well maintained during the isolation and culture period. While no treatment related lesions were observed following the in vivo exposure, histological alterations were observed at the lowest in vitro exposure. There was a significant diminution (P<0.05) in the synthesis of four cytosolic proteins following both in vivo and in vitro exposures. Diminution in these proteins was restricted to stages I-V and IX-XIV of spermatogenesis suggesting that proteins involved in the early stages of spermiogenesis are uniquely sensitive to DBA exposure. That both histology and protein synthesis were affected by physiologically relevant in vitro exposures indicates that DBA is capable of altering spermatogenesis directly.
Key words: seminiferous tubule, toxicity, dibromoacetic acid, proteins