Background: The egg yolk precursor protein vitellogenin (VTG) has proven to be a useful biomarker, used to identify organisms exposed to estrogenic compounds. Methods: We investigated variations in the VTG gene expression pattern and plasma sex steroid hormones concentrations in the yellowfin Seabream, Acanthopagrus latus, (A. latus) by various doses of bisphenol-A (BPA) exposure for 7 and 14 days. We developed a quantitative real time polymerase chain reaction (RT-PCR) assay for the expression of VTG gene in A. latus. The dose-response pattern of VTG gene expression in A. latus exposed to various doses of BPA was characterized. In order to design RT-PCR primers specific to A. latus VTG, a partial sequence of the VTG gene was obtained. Results: The RT-PCR assay was effective in detecting increased VTG gene expression in A. latus exposed to BPA. It also demonstrated that the VTG expression was affected by BPA in a dose and time-dependent manner. Plasma testosterone (T) levels were decreased in the treated fish in comparison with those found in the control group, when they were exposed to 100 µg/g of BPA and 2 µg/g of E2. In contrast, the plasma levels of 17β-estradiol (E2) were significantly increased in a dose-dependent manner. Conclusion: The results suggest that VTG mRNA quantification can provide a sensitive and early signal in the detection of estrogens in marine wildlife. It also indicated that BPA could lead to an imbalance of sex steroid hormones with potentially harmful consequences on sexually immature male A. latus.

Purpose The purpose of this paper was to identify Serratia marcescens to extract and purify prodigiosin pigment to evaluate the antibacterial potential of the pigment. Design/methodology/approach Samples were collected from shrimp aquaculture ponds. Species identification was conducted using morphological, biochemical and molecular tests. Pigment extraction and purification were carried out using column chromatography. The antibacterial effect of crude and purified prodigiosin pigment was evaluated on Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus as biofouling bacteria. In addition, the interaction between prodigiosin and proteins involved in biofilm formation was evaluated using molecular docking. Findings The results of prodigiosin extraction with solvents showed the highest percentage of pigment presence with methanol solvent in the second day of culture. The chemical structure of pure prodigiosin obtained from the column chromatography was confirmed by Fourier-transform infrared spectroscopy. Both crude and purified pigments exhibited antibacterial effects against selected bacterial strains. The antibacterial effect of the purified pigment was higher, and the highest antibacterial effect was observed on B. subtilis. Prodigiosin docking was carried out with all target proteins, and the docked energy in all of them was at an acceptable level. Originality/value Prodigiosin extracted from S. marcescens can be used as a bioactive compound to design and manufacture of anti-biofouling and anti-biofilm formation products to use extensively for industrial applications as a natural color in marine industries, food industry, cosmetics and textile productions.