Atrazine alters early sexual development of the South American silverside, Odontesthes bonariensis.

Atrazine (ATZ) is a frequent contaminant in freshwater ecosystems within agricultural regions. The capacity of this herbicide to interfere with the vertebrate endocrine system is broadly recognized, but the mechanisms and responses usually differ among species. In this study, ATZ effects on hypothalamus-pituitary-gonadal (HPG) axis key genes expression and early gonadal development were evaluated in Odontesthes bonariensis larvae waterborne exposed during the gonadal differentiation period. Fish were treated to 0, 0.7, 7.0, and 70 µg ATZ/L at 25 °C from the 2nd to 6th week after hatching (wah), and a group was kept in clean water until the 12th wah. Parallelly, a group was submitted to 0.05 µg/L of ethinylestradiol (EE2) as a positive estrogenic control. From each treatment, eight larvae were sampled at 6 wah for gene expression analysis and twelve larvae at 12 wah for phenotypic sex histological determination. The expression of gnrh1, lhb, fshb, and cyp19a1b was assessed in the head, and the ones of amha, 11ßhsd2, and cyp19a1a in the trunk. Fish growth was significantly higher in fish exposed to 7 and 70 µg ATZ/L in the 6 wah, but the effect vanished at the 12 wah. The expression of lhb was upregulated in both sex larvae exposed from 7 µg ATZ/L. However, a dimorphic effect was induced on cyp19a1a expression at 70 µg ATZ/L, up or downregulating mRNA transcription in males and females, respectively. Delayed ovarian development and increased number of testicular germ cells were histologically observed from 7 to 70 µg ATZ/L, respectively, and a sex inversion (genotypic male to phenotypic female) was found in one larva at 70 µg ATZ/L. The lhb expression was also upregulated by EE2, but the cyp19a1a expression was not affected, and a complete male-to-female reversal was induced. Further, EE2 upregulated gnrh1 in females and cyp19a1b in both sexes, but it did not alter any assessed gene in the trunk. In conclusion, ATZ disrupted HPG axis physiology and normal gonadal development in O. bonariensis larvae at environmentally relevant concentrations. The responses to ATZ only partially overlapped and were less active when compared to the model estrogenic compound EE2.

Bioautography and GC-MS based identification of piperine and trichostachine as the active quorum quenching compounds in black pepper.

In the search of new and safe antibacterial compounds, the quorum sensing system (QS) modulation by natural products has been studied. As a result, many plant-derived compounds have been identified as potent quorum sensing inhibitors. Piper nigrum L. (black pepper) ethanolic extract inhibits the QS in some Gram-negative bacteria but the active components have not been previously identified. Thus, the objective of this work was to identify the P. nigrum peppercorns main components that block the QS, applying bioassay and chromatographic techniques. Piperine and trichostachine were identified as the main components responsible for the quorum quenching (QQ) activity of P. nigrum peppercorns extract. Piperine at 30 mg/L, decreased the violacein production by Chromobacterium violaceum CV026 by 35%, without affecting bacterial growth. Piperine concentration of 40 mg/L decreases violacein production by C. violaceum CV026 by 70% and growth in only 4.34%. Trichostachine at 50 mg/L decreases violacein production by C. violaceum CV026 by 12%, without affecting bacterial growth. P. nigrum extract concentration of 0.5 g/L decreased violacein production in 40 % and no effects on growth were observed. Neither P. nigrum extract, piperine, nor trichostachine did affect QS of Pseudomonas aeruginosa PAO1. Data here described exhibit the potential of piperamides as modulators of QS, not previously reported.