Investigating the impact of chlorine dioxide in shrimp-rearing water on the stomach microbiome, gill transcriptome, and infection-related mortality in shrimp.

AIMS: This study aimed to assess the effects of chlorine dioxide (ClO2) in water on whiteleg shrimp Penaeus vannamei, evaluating its impact on the stomach microbiota, gill transcriptome, and pathogens. METHODS AND RESULTS: ClO2 was added to the aquarium tanks containing the shrimp. The application of ClO2 to rearing water was lethal to shrimp at concentrations above 1.2 ppm. On the other hand, most of the shrimp survived at 1.0 ppm of ClO2. Microbiome analysis showed that ClO2 administration at 1.0 ppm significantly reduced the α-diversity of bacterial community composition in the shrimp stomach, and this condition persisted for at least 7 days. Transcriptome analysis of shrimp gill revealed that ClO2 treatment caused massive change of the gene expression profile, including stress response genes. However, after 7 days of the treatment, the gene expression profile was similar to that of shrimp in the untreated control group, suggesting a recovery to the normal state. This 1.0-ppm ClO2 significantly reduced shrimp mortality in artificial challenges with an acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus and white spot syndrome virus, which were added to rearing water. CONCLUSIONS: The use of ClO2 at appropriate concentrations effectively eliminates a significant portion of the bacteria in the shrimp stomach and pathogens in the water. The results of this study provide fundamental knowledge on the disinfection of pathogens in water using ClO2 and the creation of semi germ-free shrimp, which has significantly decreased microbiome in the stomach.

De Novo Assembly and Annotation of the Siganus fuscescens (Houttuyn, 1782) Genome: Marking a Pioneering Advance for the Siganidae Family.

This study presents the first draft genome of Siganus fuscescens, and thereby establishes the first whole-genome sequence for a species in the Siganidae family. Leveraging both long and short read sequencing technologies, i.e., Oxford Nanopore and Illumina sequencing, we successfully assembled a mitogenome spanning 16.494 Kb and a first haploid genome encompassing 498 Mb. The assembled genome accounted for a 99.6% of the estimated genome size and was organized into 164 contigs with an N50 of 7.2 Mb. This genome assembly showed a GC content of 42.9% and a high Benchmarking Universal Single-Copy Orthologue (BUSCO) completeness score of 99.5% using actinopterygii_odb10 lineage, thereby meeting stringent quality standards. In addition to its structural aspects, our study also examined the functional genomics of this species, including the intricate capacity to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFAs) and secrete venom. Notably, our analyses revealed various repeats elements, which collectively constituted 17.43% of the genome. Moreover, annotation of 28,351 genes uncovered both shared genetic signatures and those that are unique to S. fuscescens. Our assembled genome also displayed a moderate prevalence of gene duplication compared to other fish species, which suggests that this species has a distinctive evolutionary trajectory and potentially unique functional constraints. Taken altogether, this genomic resource establishes a robust foundation for future research on the biology, evolution, and the aquaculture potential of S. fuscescens.