Project description:With increasing levels of fish meal (FM) protein in aquafeeds being replaced with soybean meal (SBM) protein, understanding the molecular mechanisms involved in response to alternative diets has become a critical concern. Thus, the goal of this study was to examine transcriptional differences in the intestine of juvenile yellow perch through RNA-sequencing (RNA-seq), after their initial introduction to a formulated diet with 75% SBM protein inclusion for 61 days, compared to those fed a traditional FM-based diet. Transcriptomic analysis revealed a concise set of differentially expressed genes in juveniles fed the SBM-based diet, the majority of which were intrinsic to the cholesterol biosynthesis pathway. Analysis of total body lipid and cholesterol levels were also investigated, with no between-treatment differences detected. Results of this study demonstrate that in response to SBM-based diets, yellow perch juveniles up-regulate the cholesterol biosynthesis pathway in order to maintain homeostasis. These findings suggest that the upregulation of the cholesterol biosynthesis pathway may negatively impact fish growth due to its large energy expenditure, and future studies are warranted.
Project description:To perform whole genome scanning for complex trait analysis, we isolated and characterized a total of 21 novel genomic-SSRs and EST-SSRs for yellow perch (Perca flavescens), using the methods of construction of SSR-enrichment libraries and EST database mining of a related species P. fluviatilis. Of 16 genomic-SSR primer pairs examined, eight successfully amplified scorable products. The number of alleles at these informative loci varied from 3 - 14 with an average of 8.5 alleles per locus. When tested on wild perch from a population in Pennsylvania, observed and expected heterozygosities ranged from 0.07 - 0.81 and from 0.37 - 0.95, respectively. Of 2,226 EST sequences examined, only 110 (4.93%) contained microsatellites and for those, 13 markers were tested, 12 of which exhibited polymorphism. Compared with genomic-SSRs, EST-SSRs exhibited a lower level of genetic variability with the number of alleles of averaging only 2.6 alleles per locus. Cross-species utility indicated that three of the genomic-SSRs and eight of the EST-SSRs successfully cross-amplified in a related species, the walleye (Sander vitreus).
Project description:Nutrient-rich, turbid river plumes that are common to large lakes and coastal marine ecosystems have been hypothesized to benefit survival of fish during early life stages by increasing food availability and (or) reducing vulnerability to visual predators. However, evidence that river plumes truly benefit the recruitment process remains meager for both freshwater and marine fishes. Here, we use genotype assignment between juvenile and larval yellow perch (Perca flavescens) from western Lake Erie to estimate and compare recruitment to the age-0 juvenile stage for larvae residing inside the highly turbid, south-shore Maumee River plume versus those occupying the less turbid, more northerly Detroit River plume. Bayesian genotype assignment of a mixed assemblage of juvenile (age-0) yellow perch to putative larval source populations established that recruitment of larvae was higher from the turbid Maumee River plume than for the less turbid Detroit River plume during 2006 and 2007, but not in 2008. Our findings add to the growing evidence that turbid river plumes can indeed enhance survival of fish larvae to recruited life stages, and also demonstrate how novel population genetic analyses of early life stages can contribute to determining critical early life stage processes in the fish recruitment process.
Project description:The purpose of this study was to evaluate the effects of environmentally relevant dietary MeHg exposures on adult female yellow perch (Perca flavescens) and female zebrafish (Danio rerio) ovarian development and reproduction. Yellow perch were used in the study for their socioeconomic and ecological importance within the Great Lakes basin, and the use of zebrafish allowed for a detailed analysis of the molecular effects of MeHg following a whole life-cycle exposure. Chronic whole life dietary exposure of F1 zebrafish to MeHg mimics realistic wildlife exposure scenarios, and the twenty-week adult yellow perch exposure (where whole life-cycle exposures are difficult) captures early seasonal ovarian development. For both species, target dietary accumulation values were achieved prior to analyses. In zebrafish, several genes involved in reproductive processes were shown to be dysregulated by RNA-sequencing and quantitative real-time polymerase chain reaction (QPCR), but no significant phenotypic changes were observed regarding ovarian staging, fecundity, or embryo mortality. Yellow perch were exposed to dietary MeHg for 12, 16, or 20 weeks. In this species, a set of eight genes were assessed by QPCR in the pituitary, liver, and ovary, and no exposure-related changes were observed. The lack of genomic resources in yellow perch hinders the characterization of subtle molecular impacts. The ovarian somatic index, circulating estradiol and testosterone, and ovarian staging were not significantly altered by MeHg exposure in yellow perch. These results suggest that environmentally relevant MeHg exposures do not drastically reduce the reproductively important endpoints in these fish, but to capture realistic exposure scenarios, whole life-cycle yellow perch exposures are needed.
Project description:This study sought to evaluate the effects of dietary MeHg exposure on adult female yellow perch (Perca flavescens) and zebrafish (Danio rerio) reproduction by relating controlled exposures with subsequent reproductive effects. Yellow perch were used in the study for their socioeconomic and ecological importance within the Great Lakes basin, and the use of zebrafish allowed for a detailed analysis of the molecular effects of MeHg. MeHg exposures at environmentally relevant levels were done in zebrafish for a full life cycle, mimicking a realistic exposure scenario, and in adult yellow perch for twenty weeks, capturing early seasonal ovarian development. In zebrafish, several genes involved in reproductive processes were shown to be dysregulated by RNA-seq and QPCR, but no significant phenotypic or physiological changes were observed with ovarian staging, fecundity, or embryo mortality. Yellow perch did not appear to be affected by MeHg, either at a molecular level, as assessed by QPCR of eight genes in the pituitary, liver, and ovary tissue, or a physiological level, as seen with ovarian somatic index, circulating estradiol, and ovarian staging. Lack of impact in yellow perch limits the usefulness of zebrafish as a model and suggests that the reproductive sensitivity to environmentally relevant levels of MeHg differs between yellow perch and zebrafish.
Project description:Transcriptome sequencing could facilitate discovery of sex-biased genes, biological pathways and molecular markers, which could help clarify the molecular mechanism of sex determination and sexual dimorphism, and assist with selective breeding in aquaculture. Yellow perch has unique gonad system and sexual dimorphism and is an alternative model to study mechanism of sex determination, sexual dimorphism and sexual selection. In this study, we performed the de novo assembly of yellow perch gonads and muscle transcriptomes by high throughput Illumina sequencing. A total of 212,180 contigs were obtained, ranging from 127 to 64,876 bp, and N50 of 1,066 bp. The assembly RNA-Seq contigs (≥200bp) were then used for subsequent analyses, including annotation, pathway analysis, and microsatellites discovery. No female- and pseudo-male-biased genes were involved in any pathways while male-biased genes were involved in 29 pathways, and neuroactive ligand receptor interaction and enzyme of trypsin (enzyme code, EC: 3.4.21.4) was highly involved. Pyruvate kinase (enzyme code, EC: 2.7.1.40), which plays important roles in cell proliferation, was highly expressed in muscles. In addition, a total of 183,939 SNPs, 11,286 InDels and 41,479 microsatellites were identified. This study is the first report on transcriptome information in Percids, and provides rich resources for conducting further studies on understanding the molecular basis of sex determinations, sexual dimorphism, and sexual selection in fish, and for population studies and marker-assisted selection in Percids.
Project description:Histologic studies of fish from Douglas Lake, Cheboygan County, Michigan, USA show that Diplostomum spp. infect the lens of spottail shiners (Notropis hudsonius) and common shiners (Luxilus cornutus). In contrast, infection was confined to the choroidal vasculature of yellow perch (Perca flavescens), and the morphology of the pigment epithelium and retina in regions adjacent to the metacercariae was abnormal. The difference in location of metacercariae within the host suggested that different Diplostomum species may infect shiners and perch in Douglas Lake. Species diversity was investigated by sequencing the barcode region of the cytochrome oxidase I gene of metacercariae. Four species of Diplostomum were identified, all four of which were present in shiner lenses; however, only Diplostomum baeri was present in the perch choroid. To determine whether infection of perch eyes affects the response of the retina to a light stimulus, electroretinograms (ERG) were recorded. The amplitude of the b-wave of the ERG was reduced and the b-wave latency was increased in infected perch, as compared to uninfected eyes, and the flicker-fusion frequency was also reduced. Infection of the yellow perch choroid by Diplostomum baeri, which shows strong host and tissue specificity, has an adverse effect on retinal function, lending support to the hypothesis that parasite-induced impairment of host vision may afford Diplostomum baeri the evolutionary benefit of increasing the likelihood of transmission, via host fish predation, to its definitive avian host.
Project description:Methylmercury (MeHg) is a pervasive and ubiquitous environmental neurotoxicant within aquatic ecosystems, known to alter behavior in fish and other vertebrates. This study sought to assess the behavioral effects of developmental MeHg exposure on larval yellow perch (Perca flavescens)-a nonmodel fish species native to the Great Lakes. Embryos were exposed to MeHg (0, 30, 100, 300, and 1000 nM) for 20 h and then reared to 25 days post fertilization (dpf) for analyses of spontaneous swimming, visual motor response (VMR), and foraging efficiency. MeHg exposures rendered total mercury (THg) body burdens of 0.02, 0.21, 0.95, 3.14, and 14.93 μg/g (wet weight). Organisms exposed to 1000 nM exhibited high mortality; thus, they were excluded from downstream behavioral analyses. All MeHg exposures tested were associated with a reduction in spontaneous swimming at 17 and 25 dpf. Exposure to 30 and 100 nM MeHg caused altered locomotor output during the VMR assay at 21 dpf, whereas exposure to 100 nM MeHg was associated with decreased foraging efficiency at 25 dpf. For the sake of comparison, the second-lowest exposure tested here rendered a THg burden that represents the permissible level of consumable fish in the United States. Moreover, this dose is reported in roughly two-thirds of consumable fish species monitored in the United States, according to the Food and Drug Administration. Although the THg body burdens reported here were higher than expected in the environment, our study is the first to analyze the effects of MeHg exposure on fundamental survival behaviors of yellow perch larvae and advances in the exploration of the ecological relevance of behavioral end points.
Project description:The objective of the present study was to compare skeletal muscle proteomic profiles, histochemical characteristics, and expression levels of myogenic regulatory factors (MRFs) between fast- versus slow-growing yellow perch Perca flavescens and identify the proteins/peptides that might play a crucial role in the muscle growth dynamic. Yellow perch were nursed in ponds for 6 weeks from larval stage and cultured in two meter diameter tanks thereafter. The fingerlings were graded to select the top 10% and bottom 10% fish which represented fast- and slow-growing groups (31 yellow perch per each group). Our statistical analyses showed 18 proteins that had different staining intensities between fast- and slow-growing yellow perch. From those proteins 10 showed higher expression in slow-growers, and 8 demonstrated higher expression in fast-growers. Fast-growing yellow perch with a greater body weight was influenced by both the muscle fiber hypertrophy and mosaic hyperplasia compared to slow-growing fish. These hyperplastic and hypertrophic growth in fast-grower were associated with not only metabolic enzymes, including creatine kinase, glycogen phosphorylase, and aldolase, but also myoD and myogenin as MRFs. Overall, the results of the present study contribute to the identification of different expression patterns of gene products in fast- and slow-growing fish associated with their muscle growth.
Project description:The current study assessed the effect of dietary canthaxanthin and lycopene supplementation at different concentrations on growth performance and antioxidant status in yellow perch (Perca flavescens). In this regard, fish with initial weight (32 ± 1.0 g) were divided into five groups in triplicate, and fed on carotenoid-free diet (control), canthaxanthin (CTX) (50 and 100 mg/kg diet), and lycopene (200 and 400 mg/kg diet) for 60 days. Growth parameters and antioxidant enzymes were evaluated after 30 and 60 days post feeding. Tissue liver and intestine from six fish per treatment was collected for antioxidant and digestive enzymes analysis. The results revealed a significant increase (P < 0.05) of lipid content in the group fed lycopene at a dietary level 400 mg/kg for 60 days, compared to the control. Moreover, dietary carotenoids exhibited no significant effect on growth performance; this was evidenced by no significant up-regulation of growth hormone (gh) and insulin-like growth factor 1b (igf-1b) genes after 30 and 60 days post feeding. Intestinal lipase and trypsin activities were significantly improved with dietary lycopene especially at a dose of (400 mg/kg diet) for 60 days. Malondialdehyde (MDA) level in liver was also significantly decreased with dietary lycopene (400 mg/kg diet) for 60 days. Hepatic superoxide dismutase (SOD), catalase (CAT), and Glutathione peroxidase (GSH-Px) activities were significantly decreased with dietary CTX, especially at dose (100 mg/kg diet) and lycopene at a concentration of 200 and 400 mg/kg diet after 60 days feeding. Additionally, the immune-related gene interleukin-1 beta (il-1b) mRNA expression level revealed up-regulation in groups fed on CTX at different concentrations for 30 days, and fish fed lycopene at a concentration level 400 mg/kg diet for 60 days. The obtained results concluded that dietary supplementation of canthaxanthin and lycopene could enhance immune response and maintain antioxidants defense of fish. Therefore, it considered as a functional aquafeed ingredient for yellow perch.