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As one of the most important contaminants, heavy metals can seriously influence human health via the food chain. In this study, the eco-toxicological effects of Cd, Pb, and Hg on Moina mongolica Daday were investigated by feeding them Chlorella sp. that contained heavy metals. The relative body lengths of the M. mongolica changed rapidly, peaking at 2 days for Hg, 6 days for Cd, and 8 days for Pb. Moreover, grazing and clearance rates of the experimental group were apparently lower than those of the control group after immersion in heavy metals. Additionally, Cd and Pd in the food significantly influenced the mean lifespan of M. mongolica of the P and F generations. Egg production per brood was also significantly impacted by Cd and Pb in the food in generation P. Interestingly, Pb was the only metal that significantly influenced the reproduction times of F, while the reproductive times were significantly influenced by Cd for generation P. Moreover, Cd, Pb, and Hg in the food significantly influenced the fecundity of generation P. Evaluation of the population growth parameters of M. mongolica revealed that the intrinsic rate of increase, net reproduction rate, and finite rate of increase were significantly influenced by Cd, Pb, and Hg in the food in generation P. Additionally, Hg slightly impacted generation time for generation P. Finally, the acute toxicity toward M. mongolica was Hg > Cd > Pb. Overall, heavy metals in the food were likely to influence the growth, survival, and population growth of M. mongolica through the food chain.

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With the increasing number of drug-resistant bacteria, there is an urgent need for new antimicrobial agents, and antimicrobial peptides (AMPs), which exist in the human non-specific immune system, are one of the most promising candidates. It is an effective optimization strategy to modify antimicrobial peptides (AMPs) according to the distribution of amino acids and hydrophobic characteristics. The addition of bacterial pheromones to the N short peptide can increase the ability to recognize bacteria. In this study, we designed and synthesized AMP1–6 by amino acid substitution of mBjAMP1. Additionally, P-6, S-6, and L-6 were designed and synthesized by adding bacterial pheromones based on 1–6. Functional tests showed that the four AMPs had the ability to kill Gram-negative Vibrio anguillarum, Pseudomonas mendocina, and Vibrio parahaemolyticus, and Gram-positive Micrococcus luteus and Listeria monocytogenes. Additionally, all four AMPs induced permeabilization and depolarization of bacterial cell membranes and increased intracellular reactive oxygen species (ROS) levels. Importantly, they had little or no mammalian cytotoxicity. At the same time, 1–6 and L-6 protected the stability of intestinal flora in Sebastes schlegelii and increased the relative abundance of Lactobacillaceae. In summary, our results indicate that the designed AMPs have broad application prospects as a new type of polypeptide antimicrobial agent.

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