Project description:Introduction: A major economic impediment to the aquaculture of marine finfish in land-based recirculating systems is maintaining the system salinity at a range for optimal growth. Florida Pompano (Trachinotus carolinus) are warm water, euryhaline, marine finfish shown to be a suitable candidate for low-salinity culture. Due to its popularity among sport and commercial fishers, high market value, and ability to readily consume pelleted feeds, the Florida Pompano has become a renewed target for commercialized aquaculture. Although the Florida Pompano has been successfully grown at various salinities, its optimal growth salinity has not yet been established. Studies have shown culturing at different salinities has an effect on digestion rates, feed utilization, and lipid biosynthesis. Identifying the optimal salinity for growth would result in decreased energy expenditure on maintaining homeostasis, since osmoregulation is a highly demanding process. This would allow for energy to be spent on the efficient use of nutrients. Methods: Our study was designed to determine how Florida Pompano larviculture at various salinities affects fish health with transcriptomics (RNA-seq) and fatty acid analysis. RNA-seq was used to identify genes actively transcribed and expressed at the time of sampling. After hatching in a salinity of ~ 30 ppt, larvae were reared in 345 L tanks at one of three salinities (10, 20, 30 ppt) in triplicate. Larvae samples for RNA-seq and fatty acid analysis were collected every three days until weaning. Samples for fatty acid composition were analyzed using a gas chromatography-mass spectrometry (GC/MS). RNA was extracted from homogenized whole-body samples using the Qiagen RNeasy Mini kit. Total RNA was sequenced on the Illumina HiSeq 4000 System. Raw sequences were filtered for low-quality sequences, aligned to the S. dumerili reference genome (NCBI Genome: 12614), and quantified. Each sampling day was compared across salinities to establish the differentially expressed genes (DEGs) between salinities. Results & Discussion: The numbers of DEGS in pooled samples was minimal (less than 15 total in each comparison) and the number of DEGS at each dph was variable. There were no significant differences between pooled samples or at each dph according to PERMANOVA analysis, but each dph was statistically different on pairwise analysis. Gene set enrichment analysis revealed that there was a downregulation of immune related genes in lower salinities versus higher salinities suggesting larvae may be dealing with less stress at lower salinities. Most osmoregulation, fatty acid, and immune related genes tested were not significantly different across salinities. This is likely be cause the Florida pompano is euryhaline and has a tolerance to the salinities selected. There was an increase in the expression levels of several immune related genes that may indicate an increase exposure to pathogens at later days post hatch likely related to feeding schedule. There was also an increase in fatty acid biosynthesis genes that corresponded with levels of fatty acids indicating a possible synthesis of essential fatty acids from precursors. Conclusions: From a transcriptomics perspective, the larvae did not show a negative response to lower salinities in comparison to higher salinities, which in fact showed upregulation of immune related genes. Further exploration of Florida pompano’s ability to biosynthesize essential fatty acids is necessary. This study will help enable the optimization of Florida Pompano larviculture using information on the optimal salinity and fatty acid content for growth and facilitate more cost-effective rearing methods.

Project description:Transcriptional profiling of different clam tissues (hemolymph and mantle) in response to QPX disease and temperautre Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. mercenaria oligoarray (15K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 Â°C) or clam healing (21 Â°C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of complement-related recognition molecules with fibrinogen or C1q domains were shown to be specially induced following QPX challenge, and the expression of these molecules was significantly higher in resistant clams as compared to susceptible ones. These highly variable immune proteins may be potent candidate molecular markers for future study of M. mercenaria resistance against QPX. Beyond the specific case of clam response to QPX, this study also provides insights into the primitive complement-like system in the hard clam. Three-condition interaction experiment (Temperature x clam/infection type x tissue type), 2 temperatures, 3 clam/infection types, 2 tissues, 3 biological replicates for each condition

Project description:Transcriptional profiling of different clam tissues (hemolymph and mantle) in response to QPX disease and temperautre Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. mercenaria oligoarray (15K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 °C) or clam healing (21 °C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of complement-related recognition molecules with fibrinogen or C1q domains were shown to be specially induced following QPX challenge, and the expression of these molecules was significantly higher in resistant clams as compared to susceptible ones. These highly variable immune proteins may be potent candidate molecular markers for future study of M. mercenaria resistance against QPX. Beyond the specific case of clam response to QPX, this study also provides insights into the primitive complement-like system in the hard clam.

Project description:Black soldier fly larvae meal (BSFL) from Hermetia illucens is a promising alternative protein source in diets for farmed fish. The larvae can efficiently convert low-value organic material into high quality protein in a production cycle with low arable land and freshwater inputs. A few recent studies have shown that BSFL is a suitable protein source for Atlantic salmon (Salmo salar) in smaller controlled experiments. However, industry-relevant field trials conducted under large scale near-commercial conditions over a longer period are lacking. In this study, a feeding trial was performed to evaluate the impact of BSFL on growth performance and health of Atlantic salmon during the grow out phase in seawater, in a commercial site in Vestland county, Norway. A total of 320,000 post-smolt Atlantic salmon were distributed into six duplicate sea cages and fed one of three diets (commercial-like control diet and two test diets partially replacing the protein content of the control diet with 4 % and 8 % defatted BSFL meal) for 21 weeks, until a relevant commercial slaughter size of 4.5-5.0 kg was reached. Health parameters were assessed including histology of the distal intestine (DI), in addition to DI microbiota identification (by 16s rRNA-seq) and salmon RNA-seq of DI and head kidney (HK). The results showed that the inclusion of BSFL meal supported growth performance and had no adverse effect on gut health. The beta diversity of the distal intestine microbiota and the relative abundance of families Lactobacillaceae and the chitinolytic Bacillaceae increased in the fish fed the BSFL diets. Additionally, no histopathological changes were attributable to BSFL meal intake. Results from RNA-seq in DI revealed that BSFL inclusion modulates metabolic processes associated with lipids, the response to estrogens, the activity of immune receptors (to chemokines), phagocytosis and extracellular vesicles. Based on these results, black soldier fly larvae meal is a suitable alternative protein ingredient in inclusions of up to at least 8 % for Atlantic salmon under industrial fish farming conditions.

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