OBJECTIVES To determine the detrimental role of tetrachlorodibenzo‐p‐dioxin (TCDD) in testicular histology, spermatogenesis‐related panels and proteome, and serum sex hormone levels. MATERIALS AND METHODS In all, 40 male rats were divided into equal groups: a normal control (NC) group that received vehicle and saline, and a TCDD‐treated (TT) group injected intraperitoneally with TCDD (one dose, 50 µg/kg body weight). The rats were killed 4 weeks after TCDD exposure and testicular weight, histopathology, proteome and variables related to spermatogenesis, and serum sex hormone levels were investigated. RESULTS TCDD induced a significant decrease in testicular weight, Johnsen’s score, seminiferous tubular size, percentage of tubules containing sperm, sperm counts, germ cell counts and Sertoli cell index. In addition, there was a significant decrease in serum testosterone level (P < 0.01) and a remarkable increase in oestradiol (P < 0.01), follicle‐stimulating hormone (P < 0.05) and luteinizing hormone (P < 0.05) levels in the TT group. The expression of six testicular proteins including testis‐specific heat shock protein (Hsp70), protein disulphide isomerase A3 precursor, 3‐phosphoglycerate dehydrogenase, nonmuscle myosin heavy‐chain type B‐like protein, and superoxide dismutase 1 were significantly up‐regulated (P < 0.05–0.01). Interestingly, fertility protein SP22 and phosphatidylethanolamine‐binding protein were down‐regulated but this was only significant for fertility protein SP22 (P < 0.05). CONCLUSION TCDD induces marked histological changes in the testis, impairs variables related to spermatogenesis, and increases serum oestradiol levels but decreases testosterone levels. In particular, TCDD disturbs testicular proteome profiles in rats.

The unicellular cyanobacterium Synechocystis sp. PCC 6803 glides toward a light source through the interplay of positive phototaxis genes and proteins. In genetic analysis, the complete disruption of the hybrid sensory kinase sll0043 produced negative phototaxis. Furthermore, Sll0043 was found to be a hub protein by in silico prediction of protein-protein interaction, in which Sll0043 was predominantly linked to seven two-component proteins with high confidence. To understand the regulation and networking of positive phototaxis proteins, the proteomic profile of the sll0043 mutant was compared to that of wild-type. In the sll0043 mutant, 18 spots corresponding to 15 unique proteins were altered by 1.3 to 59 fold; the spots were identified by 2-DE/MALDI-MS analysis. Down-regulated proteins in the sll0043 null-mutant included chaperonins, superoxide dismutase, and phycocyanin beta-subunit. In contrast, nine proteins involved in photosynthesis, translation, regulatory function, and other functions were up-regulated. In particular, a twitching motility protein (PilT1) was induced over 2-fold in sll0043 mutant. Moreover, semi-quantitative and quantitative RT-PCR analysis revealed that pilin (pilA1), pili motor (pilT1), and pili switch gene (pilT2) were significantly increased in sll0043 mutant. These results suggest that the hybrid kinase Sll0043 regulates positive phototaxis by suppressing the expression of pili biosynthesis and regulatory genes and through the interplay with positive phototaxis/motility two-component proteins.