Aeromonas veronii is as an important opportunist pathogen of many aquatic animals, which is wildly distributed in various aquatic environments. In this study, a dominant bacterium GJL1 isolated from diseased M. salmoides was identified as A. veronii according to the morphological, physiological, and biochemical characteristics, as well as molecular identification. Detection of the virulence genes showed the isolate GJL1 carried outer membrane protein A (ompA), flagellin (flgA, flgM, flgN), aerolysin (aer), cytolytic enterotoxin (act), DNases (exu), and hemolysin (hly), and the isolate GJL1 also produced caseinase, lipase, gelatinase, and hemolysin. The virulence of strain GJL1 was confirmed by experimental infection; the median lethal dosage (LD₅₀) of the GJL1 for largemouth bass was 3.6 × 10⁵ CFU/mL, and histopathological analysis revealed that the isolate could cause obvious inflammatory responses in M. salmoides. Additionally, the immune-related gene expression in M. salmoides was evaluated, and the results showed that IgM, HIF-1α, Hep-1, IL-15, TGF-β1, and Cas-3 were significantly upregulated after A. veronii infection. Our results indicated that A. veronii was an etiological agent causing the mass mortality of M. salmoides, which contributes to understanding the immune response of M. salmoides against A. veronii infection.

This article explores the impact of inlet pre-swirl on pressure pulsation in a mixed-flow centrifugal pump through a combination of numerical simulations and experimental verification. Firstly, the mixed-flow centrifugal pump’s performance was initially determined through both numerical calculations and experiments. The comparison between them indicated the high accuracy of the numerical method adopted in this paper. Next, the flow pattern within the pump at various inlet pre-swirl angles was carefully compared and analyzed. It was found that positive impulse angle and inlet displacement could lead to circumferential inhomogeneity of the flow field within the impeller, while inlet pre-swirl can significantly counteract the effect of positive impulse angle. The impact of inlet pre-swirl on the flow pattern near the blade inlet will change the intensity of the secondary flow within the impeller passage. Variations in the intensity of the secondary flow can directly affect the strength of the wake and jet in the chamber. Then, the pressure pulsations within the chamber were compared and analyzed for various inlet pre-swirl angles. The results revealed that as the inlet pre-swirl angle increased, the intensity of pressure pulsation decreased significantly. This discovery sheds light on the influence mechanism of inlet pre-swirl on pressure pulsation within mixed-flow pumps, potentially serving as a theoretical foundation for enhancing the operational stability of mixed-flow centrifugal pumps.

The complete mitochondrial genome of Calliptamus barbarus (Orthoptera: Acrididae: Calliptaminae) from Qinghai Lake, Qinghai province, China is a circular molecule of 15,668 bp in size, and contains 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and one AT-rich region. The overall nucleotide composition is 41.8% of A, 30.9% of T, 11.3% of G, and 16.0% of C. All PCGs started with typical ATN codon, e.g. one with ATA, two with ATT and ATC, and eight with ATG. Eleven PCGs ended with complete stop codon TAA, and the other two genes (ND1 and ND4L) ended with TAG. Phylogenetic trees were reconstructed with 13 PCGs using Bayesian Inference (BI) and maximum likelihood (ML) to validate the taxonomic status of C. barbarus, exhibiting the close relationships with C. abbreviates + C. italicus.