Mercuric resistant bacteria Aeromonas exhibits neurologic toxic effects on the developmental motor reflexes, and brain oxidative stress in mice offspring.

Mercury and its derivatives even in small concentration may cause a major human health problem. Though not reported in detail, there are various aquatic bacterial species that produce small quantities of methyl mercury (MM) growing under aerobic conditions. Consumption of food derived from sources contaminated with such bacteria within therapeutic doses and exposure to different forms of MM compounds through such sources may induce substantial toxic effects. In the present study, the perinatal oral exposure of pregnant mice to two strains of mercury resistant bacteria (MRB), Aeromonas KSU5 MRB and KSU6 MRB resulted in a significant reduction in postnatal body weight gain, delays in the opening of the eyes and appearance in the body hair fuzz, and deficits in the developing sensory motor reflexes in the mice pups during their weaning period on post-natal day (PD)7, PD14 and PD21. A significant and MM producing concentration-dependent disturbance in the levels of neurotransmitters like dopamine (DA) and serotonin (5-HT); non-enzymatic oxidative stress (OS) indices like thiobarbituric acid-reactive substances (TBARS) and total reduced glutathione (GSH); and enzymatic OS indices like glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were observed in the forebrain region of the offspring at weaning period (PD7, PD14, and PD21), at adolescent age (PD30), and at adult age (PD36). Thus, perinatal exposure to MRB can affect developing fetus, raising the concerns for it's potential neurotoxic hazards. A reduced exposure to mercury during pregnancy is of crucial importance in preventing mercury-induced neurotoxicity in the offspring.

Identification of the Zinc Finger Protein ZRANB2 as a Novel Maternal Lipopolysaccharide-binding Protein That Protects Embryos of Zebrafish against Gram-negative Bacterial Infections.

Zinc finger ZRANB2 proteins are widespread in animals, but their functions and mechanisms remain poorly defined. Here we clearly demonstrate that ZRANB2 is a newly identified LPS-binding protein present abundantly in the eggs/embryos of zebrafish. We also show that recombinant ZRANB2 (rZRANB2) acts as a pattern recognition receptor capable of identifying the bacterial signature molecule LPS as well as binding the Gram-negative bacteria Escherichia coli, Vibrio anguilarum, and Aeromonas hydrophila and functions as an antibacterial effector molecule capable of directly killing the bacteria. Furthermore, we reveal that N-terminal residues 11-37 consisting of the first ZnF_RBZ domain are indispensable for ZRANB2 antimicrobial activity. Importantly, microinjection of rZRANB2 into early embryos significantly enhanced the resistance of the embryos against pathogenic A. hydrophila challenge, and this enhanced bacterial resistance was markedly reduced by co-injection of anti-ZRANB2 antibody. Moreover, precipitation of ZRANB2 in the embryo extracts by preincubation with anti-ZRANB2 antibody caused a marked decrease in the antibacterial activity of the extracts against the bacteria tested. In addition, the N-terminal peptide Z1/37 or Z11/37 with in vitro antibacterial activity also promoted the resistance of embryos against A. hydrophila, but the peptide Z38/198 without in vitro antibacterial activity did not. Collectively, these results indicate that ZRANB2 is a maternal LPS-binding protein that can protect the early embryos of zebrafish against pathogenic attacks, a novel role ever assigned to ZRANB2 proteins. This work also provides new insights into the immunological function of the zinc finger proteins that are widely distributed in various animals.