Aquaculture Research最新文献

Infectious pancreatic necrosis (IPN) has highly contagious disease and an important viral disease-causing economic loss for fish farming, which has developed in recent years. The virus is the first fish virus isolated in vitro. Horizontal and vertical transmission plays an important role in the spread of the virus. In addition, the resistance of the virus to environmental conditions makes it difficult to control the virus. Therefore, it is important to develop vaccines and analyze the effectivity of antivirals for the prevention and control of infectious pancreatic necrosis virus (IPNV) infection. This study investigated the antiviral effect of two different mutagens, ribavirin (RBV) and 5-fluorouracil (5-FU), on IPNV, and their mutation-inducing potential on the susceptible cell line Epithelioma papulosum cyprini (EPC), in vitro. For this purpose, cytotoxic doses of RBV and 5-FU were first investigated and were found to be 50 and 100 µM/mL, respectively. Serial passages of IPNV were then performed, both with and without drug suppression. At the end of each passage, confirmation was performed by real-time transcriptase polymerase chain reaction (RT-PCR). Serial passages were checked for viral load using quantitative RT-PCR (qRT-PCR). The viral copy number of the RBV-suppressed virus decreased from 1.18 × 10⁵ copies/µL for the 1st passage to 1.49 × 10² copies/µL at the end of the 5th passage. The viral copy number of the 5-FU-suppressed virus decreased gradually with each passage, from 3.84 × 10³ copies/µL for the 1st passage to 1.78 × 10² copies/µL at the end of the 5th passage, with the exception of the 2nd passage, where the viral load increased. Passages 1st and 5th of both the RBV- and 5-FU-suppressed virus, and the non-drug-suppressed virus, were checked by partial sequence, but mutations in VP2 were not observed. In conclusion, in this study, we obtained data on the antiviral activity of two mutagens on IPNV.

Over the past three decades, global aquaculture production has significantly increased, emphasizing the need for sustainable and cost-effective alternatives to traditional fish meal in aquafeed. This study’s objective was to elucidate the impact of utilizing a combination of fish and crustacean byproducts—namely, smoked salmon (Salmo salar) skins (SSs), smoked salmon trimmings (STs), and shrimp (Litopenaeus setiferus) heads (SHs)—as primary ingredients in pelleted aquafeed. Importantly, this work focuses on nonextruded pellets, where the physical properties are more influenced by ingredient composition compared to extruded pellets. The tested formulations were not nutritionally comprehensive for any specific commercial aquaculture species, as the goal of this study was to highlight the effect of the byproducts on pellet physical integrity. SH and de-oiled solid fractions of SS and ST were dehydrated for 24 h at 60°C, ground into dried powders, and formulated into six samples at a 1:1 (w/w) ratio and one sample at a 1:1:1 ratio. Potato starch (80 g/kg) was added to each sample, along with varying deionized (DI) water amounts before steam conditioning, pelletizing, and drying. Analyses included pellet nutrient composition, floatability, durability, water stability, bulk density, water absorption index (WAI), and water solubility index (WSI). Results revealed that SS pellets exhibited 97% floatability at 1 min, decreasing to 70% at 60 min. SS and ST combinations showed slow sinking behavior, while all other formulations sank quickly. Pellets containing SH had lower water stability (65.65% ± 4.44% to 0.05% ± 0.07%), in contrast to over 92% for SS and ST pellets. Durability ranged from 98.48% ± 0.37% for SS to 75.29% ± 5.82% for SH and ST combinations, further underlining the significant impact of byproduct choice on pellet performance. Overall, the inclusion of SS or ST and their combination as primary ingredients for pelleted aquafeed produced pellets that scored well on important quality parameters, while pellets containing SH performed poorly. This information may be used in the development of nutritionally comprehensive nonextruded aquafeeds containing SS and/or ST to conduct feeding trials with commercially relevant species.

In order to produce gynogenetic diploid of Manila clam, Ruditapes philippinarum, we studied the optimal conditions of gynogenetic diploid induced by ultraviolet (UV). The irradiance of UV-induced sperm was 230 μW (cm²·s), and the irradiation time was 0, 3, 6, 9, 12, 15, 18, 21, 24, and 27 s. After the egg fertilized with genetically inactivated sperm, the fertilized eggs were treated with cytochalasin B (CB) at different concentrations of 0, 0.25, 0.50, 0.75, and 1.0 mg/L for 20 min. The ploidy of larvae under different induction concentrations were analyzed by flow cytometry, and the chromosome division process during sperm entry and cleavage was observed by fluorescence microscope. In addition, the ultrastructure of sperm, embryonic development, and chromosome were observed. The results showed that the fertilization rate and cleavage rate decreased gradually with the prolongation of UV irradiation time. We found UV irradiation for 9 s was the optimal time for haploid formation, with an induction rate of 100%. The CB treatment at 0.75 mg/L was the optimal concentration for the formation of D-larvae, and the induction rate was 9.60% ± 5.10%. The results showed that the optimal conditions for inducing gynogenetic diploid of R. philippinarum were irradiation with UV intensity of 230 μW (cm²·s) for 9 s and inhibited second polar body release by CB at concentration of 0.75 mg/L. In this study, the conditions for inducing Manila clam gynogenetic diploid were obtained, which lays the basis for further genetic research on the gynogenesis of R. philippinarum.

In order to create new value in biomass production using sterile Ulva with high production efficiency, we selected sterile Ulva with high culture stability from the coast of Imari City in Japan and investigated the conditions for generating high concentrations of dissolved oxygen through photosynthesis using the sterile Ulva. In the cultivation of sterile Ulva, we investigated the conditions for generating high concentrations of dissolved oxygen (DO) by controlling conditions such as aeration, NO₃-N concentration, and population density. As a result, we found that under the cultivation control conditions we found, DO reached about 3.8 times the saturation concentration after 3 h. It was found that this high level of DO can be maintained if the supersaturated DO seawater obtained here is properly sealed. Seawater containing high levels of DO is essential for the cultivation of oysters and shellfish, which also prefer a growth temperature of 20°C−25°C. Therefore, from the perspective of creating new value in biomass production, we developed a new system for simultaneously cultivating sterile Ulva and cultivating oysters.

Aquaponic production relies on microbial activity to convert fish wastes into nutrients for plants. An aquaponic system contains multiple compartments that each have varying environmental pressures that can impact the types of microbes living in the compartment. Furthermore, differences in fish and plant species, system startup and management, and water source can impact microbial communities that colonize an aquaponic system. In this study, we sampled two aquaponic facilities that each operated six replicate aquaponic systems. Metataxonomic analyses were performed on the samples to compare the microbial communities of aquaponic facilities in Minnesota (MN) and Wisconsin (WI), assess the consistency of the microbial communities across multiple systems within a single facility, and evaluate the abundance and types of microbes present within each compartment of a system. Proteobacteria, Bacteroidetes, and Actinobacteria were common in both facilities, but nitrifying organisms were in greater abundance at the WI facility. Microbial communities were largely consistent among systems within a facility, but microbial communities among different compartments of the systems varied. Nitrifying organisms were primarily associated with the biofilter compartment of the MN systems but were found throughout the WI systems, which do not have a dedicated biofiltration compartment. While nitrifying organisms have an important role in an aquaponic system, they comprise less than 10% of the total microbial community of the aquaponic systems we sampled. Other taxa are likely to have equally important roles in the productivity of an aquaponic system, but those taxa and their functions have not been well characterized, and it is unclear how system startup, management, and other factors impact colonization and maintenance of these taxa.