Dietary Protein Optimization for Growth and Immune Enhancement in Juvenile Hybrid Sturgeon (Acipenser baerii × A. schrenckii): Balancing Growth Performance, Serum Biochemistry, and Expression of Immune-Related Genes.

This study aimed to evaluate the effects of dietary protein levels on growth performance, serum indices, body amino acid composition, and intestinal gene expression in juvenile hybrid sturgeon (Acipenser baerii × A. schrenckii). Hybrid sturgeons (initial weight 29.21 ± 2.04 g) were fed isolipidic diets containing 30%, 33%, 36%, 39%, 42% or 45% crude protein for 12 weeks (n = 18 tanks, 30 fish/tank). Results showed significant differences between treatments, where weight gain and protein efficiency ratio peaked optimally between 35.9% and 38.3% dietary protein. Serum parameters such as glucose, alanine aminotransferase, aspartate aminotransferase, superoxide dismutase, and lipid peroxidation levels varied significantly with changes in dietary protein levels. Specifically, the highest enzymatic activities and growth parameters were observed in groups fed with 33% to 39% protein, enhancing whole-body concentrations of lysine, leucine, phenylalanine, proline, and glutamic acid. Immune parameters such as immunoglobulin M and lysozyme activity also showed peak levels at higher protein concentrations, particularly notable at 42% for lysozyme and 36% for both component 3 and immunoglobulin M. Gene expression related to immune and growth pathways, including MyD88, TLR1, IL-8, IL-6, NF-κB, and IL1ß, was significantly upregulated at protein levels of 33% to 36%, with a noted peak in expression at 39% for TLR1, IL-10, and TOR signaling genes, before diminishing at higher protein levels. Overall, the dietary protein requirement for juvenile hybrid sturgeon ranges from 35.9% to 38.3% crude protein.

Uranium speciation and distribution on the surface of Shewanella putrefaciens in the presence of inorganic phosphate and zero-valent iron under anaerobic conditions.

Shewanella putrefaciens (S. putrefaciens) is one of the main microorganisms in soil bioreactors, which mainly immobilizes uranium through reduction and mineralization processes. However, the effects of elements such as phosphorus and ZVI, which may be present in the actual environment, on the mineralization and reduction processes are still not clearly understood and the environment is mostly in the absence of oxygen. In this study, we ensure that all experiments are performed in an anaerobic glove box, and we elucidate through a combination of macroscopic experimental findings and microscopic characterization that the presence of inorganic phosphates enhances the mineralization of uranyl ions on the surface of S. putrefaciens, while zero-valent iron (ZVI) facilitates the immobilization of uranium by promoting the reduction of uranium by S. putrefaciens. Interestingly, when inorganic phosphates and ZVI co-exist, both the mineralization and reduction of uranium on the bacterial surface are simultaneously enhanced. However, these two substances exhibit a certain degree of antagonism in terms of uranium immobilization by S. putrefaciens. Furthermore, it is found that the influence of pH on the mineralization and reduction of uranyl ions is far more significant than that of inorganic phosphates and ZVI. This study contributes to a better understanding of the environmental fate of uranium in real-world settings and provides valuable theoretical support for the bioremediation and risk assessment of uranium contamination.