Search

The current study evaluated the effects of nano delivery of Spirulina platensis on growth performance, digestive enzymes, and biochemical, immunological, and antioxidative status, as well as resistance to Aeromonas veronii and some physical stressor challenges in Nile tilapia, Oreochromis niloticus. Three experimental fish groups (n = 270) with mean weights of 26 ± 0.30 g and mean lengths of 10 ± 0.5 cm were used; the first additive-free basal diet served as the control group, whereas the following two groups were supplemented with spirulina nanoparticles (SPNP) at 0 (control), 0.25, and 0.5%/kg diet for 4 weeks. Following the feeding trial, fish were challenged with hypoxia, cold stresses, and pathogenic bacteria (A. veronii) infection (9 × 108 CFU/ml). SPNP supplementation, especially 0.5%, (p 0.25% SPNP > 0% SPNP compared with the control. Protection in the incorporated fish groups exposed to A. veronii was 100% compared with the control group, which showed 50% cumulative mortalities. In conclusion, dietary SPNP supplementation improved growth performance, antioxidant activity, immune response, digestive enzymes, related gene expression, and resistance of Nile Tilapia to hypoxia, cold, and A. veronii infection. Thus, SPNP could be used as a natural therapy for controlling those stressors.

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.

In current study, Yellow perch (P. flavescens) was exposed to common forms of physical stressors and antioxidative effects of dietary incorporated Astragalus membranaceus (AM) and Glycyrrhiza glabra (liquorice) were assessed. To address this, for a four-week five groups of fish (31 ± 1.0 g, average weight) received 1, 2, and 3% (w/w) Glycyrrhiza glabra; and 1% G. glabra- A. membranaceus mixture daily. Control group fed an additive-free basal diet. Immunological, biochemical and histopathological profiles were evaluated; and fish were redistributed to be exposed to heat, cold, hypoxia and capture stressors. The current findings demonstrated that A. membranaceus and G. glabra dietary incorporation remarkably enhanced antioxidative and biochemical parameters. Also, the study showed markedly up-regulation of related genes expression; and revealed better liver histology in supplemented groups over the control. In conclusion, A. membranaceus and G. glabra dietary supplementation markedly enhanced antioxidantive responses throughout the experimental period, indicating the ability of both herbal plants to confer protection against different physical stressors.

Terminologies of ovary development, by somewhat subjective describing and naming main changes of oocytes, have been criticized for confusing and inconsistency of terms and classifications, and the incurred consequences impede communication among researchers. In the present work, we developed regression between ovary development and three ribosome RNA (rRNA) indexes, namely 5S rRNA percent, 18S rRNA percent, and 5S–18S rRNA ratio, using close relationship between volume percent of primary growth stage oocytes or gonadosomatic index and rRNA content, demonstrating species-specific quantification of ovary development can be established in species with either synchronous and asynchronous oogenesis. This approach may be extended to any species with primary growth oocytes, e.g. anurans and reptiles, to predict maturity stages in females. We further confirmed that 5S rRNA percent and 5S/18S rRNA ratio can serve as markers to distinguish sexes unambiguously. A micro-invasive sampling method may be invented for non-lethal prediction of ovary development and sex because only a small amount of ovary sample (

The use of genotyping has enabled the characterization and mapping of genes and the study of stock identification, population genetics, evolution, ecological speciation, and invasion, as well as genomic evaluation, sex control and sex determination, nutrition, biomarkers for disease, and quantitative trait loci mapping for marker-assisted selection in fisheries and aquaculture. High-throughput variant discovery has been made possible in multiple species by the recent advent of next-generation DNA sequencing technologies. New genotyping methods that are high-throughput, accurate, and inexpensive are urgently needed for gaining full access to the abundant genetic variation of organisms. This approach is known as genotyping-by-sequencing (GBS), which holds great promise as a research tool because of its ability to allow simultaneous marker discovery and genotyping at low cost and with a simple molecular biology workflow for fisheries and aquaculture studies. Since it was first developed for rice in 2009, GBS has been applied in over 50 species/studies by the end of 2014. It is also increasingly in use in fisheries and aquaculture and has been applied in nearly 40 species/studies from 2015 to present. This review summarizes the genotyping methodologies, recent advances in next-generation DNA sequencing technologies to achieve GBS, and the promises this approach holds as a genome-wide genotyping application in fisheries and aquaculture. Additionally, we discuss the potential of whole-genome sequencing (WGS) in GBS and present the advances of WGS in fisheries and aquaculture.

Although largemouth bass Micropterus salmoides has shown its extremely economic, ecological, and aquacultural significances throughout the North American and Asian continents, systematic evaluation of genetic variation and structure of wild and cultured populations of the species is yet to be documented. In this study, we investigated the genetic structure of M. salmoides from 20 wild populations and five cultured stocks across the United States and China using eight microsatellite loci, which are standard genetic markers for population genetic analysis. Our major findings are as follows: (1) the result of Fst showed largemouth bass had high genetic differentiation, and the gene flow indicated the genetic exchange among wild populations is difficult; (2) AMOVA showed that 14.05% of the variation was among populations, and 85.95% of the variation was within populations; (3) The majority of largemouth bass populations had a significant heterozygosity excess, which is likely to indicate a previous population bottleneck; (4) Allelic richness was lower among cultured populations than among wild populations; (5) Effective population size in hatcheries could promote high levels of genetic variation among individuals and minimize loss of genetic diversity; China’s largemouth bass originated from northern largemouth bass of USA. The information provides valuable basis for development of appropriate conservation policies for fisheries and aquaculture genetic breeding programs in largemouth bass.

The effects of dietary administration of Astragalus membranaceus nanoparticles (ANP) on immune and anti-oxidative responses, growth performance and disease resistance of Oreochromis niloticus were evaluated in the present study. Fish were divided into three groups and received the ANP at rates of 0 (control), 1, and 2%/kg diet for four weeks. After the four-week feeding trial, three fish from each replicate were sampled for immune and anti-oxidative responses evaluation, ten fish from each group were challenged with A. veronii, and nine fish from each group were subjected to cold and hypoxia challenges. It was obvious from the results that ANP significantly enhanced lysozyme activity and nitrous oxide (NO) activities, as well as improved superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities. Also, aspartate aminotransferase, alanine transaminase, glucose, and cortisol measurements showed significantly lower levels in incorporated groups compared to the control. Growth performance; and amylase and lipase digestive enzymes activities also showed markedly improved results. Expression of heat shock protein 70 (HSP70) and interleukin 1, beta (IL-1β) genes were significantly upregulated throughout the entire experimental period. When challenged with A. veronii, the mortality of treated groups was significantly (P

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.

Arsenic (As) is found in waters such as seawater, warm springs, groundwater, rivers, and lakes. In aquatic environments, As occurs as a mixture of arsenate and arsenite, with arsenate usually predominating. The unrestricted application of As pesticides, industrial activities, and mining operations has led to the global occurrence of soluble As above permissible levels of 0.010 mg/L. Continuous exposure of freshwater organisms including fish to low concentrations of As results in bioaccumulation, notably in liver and kidney. As a consequence As induces hyperglycemia, depletion of enzymatic activities, various acute and chronic toxicity, and immune system dysfunction. Here we review arsenic chemistry, the occurrence of arsenic in aquatic system, the transformation and metabolism of arsenic; arsenic bioaccumulation and bioconcentration; behavioral changes; and acute and other effects such as biochemical, immunotoxic, and cytogenotoxic effects on fish.

The current work assessed the potential immunomodulatory and growth-promoting effects of Astragalus membranaceus (AM) and Glycyrrhiza glabra (liquorice) in Yellow perch (Perca flavescens). In this regard, fish with an average weight of 31 ± 1.0 g were divided into five groups, and fed daily with an additive-free basal diet (control); 1, 2, and 3% (w/w) Glycyrrhiza glabra, and the fifth diet was incorporated with a combination of 1% G. glabra-AM for a four-week period. Immunological, biochemical and growth parameters were measured; and sub-groups of fish were exposed to 1-week starvation. The results showed that incorporating AM and liquorice in the diet significantly improved Immunological [superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), Lipid peroxidase (LPx) and lysozyme activities], biochemical [Aspartate Aminotransferase (AST) and Alanine Transaminase (ALT) activities; and glucose and cortisol concentrations] and growth performance parameters [body mass gain (BMG), specific growth rate (SGR), length, condition factor (K) and feed conversion ratio (FCR)]. In addition, markedly up-regulated the expression of related genes [Insulin-Like Growth Factor-1 (IGF-1), Serum amyloid A (SAA), Complement Component C3 (CCC3), Alpha 2 Macroglobulin (A2M), SOD and GPx] in treated fish groups compared to the control. Conclusively, feeding AM and liquorice diets significantly increased (P

In order to evaluate utilization variation of, and growth response to, soybean meal diets in largemouth bass for breeding programs, test diets with 0%, 35%, and 50% fishmeal having been replaced by soybean meal (SBM; S0, S35, and S50) were administered to three northern strains of largemouth bass (LMB; Jones, Marlow, and Remlinger). In the S35 and S50 groups, the Marlow and Remlinger strains had much better growth response to soybean meal diet (SMD) than the Jones strain, indicating that these two strains can better utilize diets containing high level of SMD. The results suggest that genetic variation exists for growth and feed efficiency in LMB fed diets containing both SBM and fishmeal, and genetic improvement may be possible for the trait of feed efficiency. In all the three strains, the growth performance of individuals in the S35 and S50 groups declined when compared with the S0 group, and the specific growth rate and weight gain correlated negatively with dietary levels of SBM. Genes that were differentially expressed between dietary SBM levels were identified. Transcripts of genes related to insulin-signaling pathway and fatty acid metabolism and biosynthesis were significantly downregulated in the S35 and S50 groups compared with the S0 group. Interestingly, several transcripts of genes (egfr, pla2g4, and ugt) involved in GnRH-signaling pathway and steroid hormone biosynthesis were also downregulated in the S35 and S50 groups, inferring that feeding with SMD could impair the sexual development of juvenile LMB. Likewise, the genes related to insulin signaling and fatty acid metabolism and biosynthesis were downregulated in the Jones strain compared to the Marlow and Remlinger strains in all three treatments. Overall, the Marlow and Remlinger strains exhibited better adaptation to SBM diets, and could be considered as potential breeding candidates. These results also suggest that insulin-signaling pathway and fatty acid metabolism and biosynthesis play important roles in adaptation to diets with high levels of SBM in LMB. This study provides useful information for LMB breeding programs, and it contributes to our understanding of genetic mechanisms related to growth performance of LMB fed with high levels of SMB.

Egg disinfection is considered the most important routine work in hatcheries to avoid fungal and/or bacterial infection of fish eggs. The aim of this study was to determine the effectiveness of three disinfectants: formalin, iodine and sodium chloride on the hatching success of yellow perch eggs. The disinfectants were tested in triplicate at different concentrations for 15 and 30 min bath treatments. Two experiments were conducted; formalin at five concentrations (25, 50, 100, 150 and 200 mg L−1) and 25 mg L−1 iodine were tested in the first experiment. The second experiment involved formalin at three concentrations (250, 500 and 1000 mg L−1), iodine at three concentrations (50, 100 and 250 mg L−1) and sodium chloride at three concentrations (500, 1000 and 3000 mg L−1) were used. Iodine and sodium chloride-treated eggs hatched earlier than formalin-treated eggs. The highest mean percentage of eyed stage, hatching rate and survival to first feeding fry was observed at 200 mg L−1 formalin for 30 min, 50 mg L−1 iodine for 15 min and 500 mg L−1 sodium chloride for 30 min. High concentrations of formalin (1000 mg L−1), iodine (250 mg L−1) and sodium chloride (1000 and 3000 mg L−1) showed toxicity to yellow perch eggs, resulting in low hatching rate and survival to first feeding fry. We recommended formalin at a concentration of 150–200 mg L−1 for 30 min as an effective, easily available and low-cost disinfectant for routine use to improve yellow perch hatchability.

Stress is a major factor that causes diseases and mortality in the aquaculture industry. The goal was to analyze the expression of stress-related biomarkers in response to different stressors in yellow perch, which is an important aquaculture candidate in North America and highly sensitive to handling in captivity. Three fish groups were established, each having four replicates, and subjected to water temperatures of 14, 20, and 26°C and acute handling stress was performed followed by a salt treatment for 144h at a salinity of 5 ppt. Serum and hepatic mRNA levels of heat shock protein (hsp70), insulin-like growth factor 1 (Igf1), glutathione peroxidase (Gpx), superoxide dismutase 1 (Sod1), and glutathione reductase (Gsr) were quantified at seven times interval over 144 h using ELISA and RT-qPCR. Handling stress caused a significant down-regulation in Hsp70, Gpx, Sod1, and Gsr at a water temperature of 20°C compared to 14 and 26°C. Igf1 was significantly upregulated at 20°C and down-regulated at 14 and 26°C. Salt treatment had a transient reverse effect on the targeted biomarkers in all groups at 72 h, then caused an upregulation after 144 h, compared to the control groups. The data showed a negative strong regulatory linear relationship between igf1 with hsp70 and anti-oxidative gene expressions. These findings could provide valuable new insights into the stress responses that affect fish health and could be used to monitor the stress.

Advancing the production efficiency and profitability of aquaculture is dependent upon the ability to utilize a diverse array of genetic resources. The ultimate goals of aquaculture genomics, genetics and breeding research are to enhance aquaculture production efficiency, sustainability, product quality, and profitability in support of the commercial sector and for the benefit of consumers. In order to achieve these goals, it is important to understand the genomic structure and organization of aquaculture species, and their genomic and phenomic variations, as well as the genetic basis of traits and their interrelationships. In addition, it is also important to understand the mechanisms of regulation and evolutionary conservation at the levels of genome, transcriptome, proteome, epigenome, and systems biology. With genomic information and information between the genomes and phenomes, technologies for marker/causal mutation-assisted selection, genome selection, and genome editing can be developed for applications in aquaculture. A set of genomic tools and resources must be made available including reference genome sequences and their annotations (including coding and non-coding regulatory elements), genome-wide polymorphic markers, efficient genotyping platforms, high-density and high-resolution linkage maps, and transcriptome resources including non-coding transcripts. Genomic and genetic control of important performance and production traits, such as disease resistance, feed conversion efficiency, growth rate, processing yield, behaviour, reproductive characteristics, and tolerance to environmental stressors like low dissolved oxygen, high or low water temperature and salinity, must be understood. QTL need to be identified, validated across strains, lines and populations, and their mechanisms of control understood. Causal gene(s) need to be identified. Genetic and epigenetic regulation of important aquaculture traits need to be determined, and technologies for marker-assisted selection, causal gene/mutation-assisted selection, genome selection, and genome editing using CRISPR and other technologies must be developed, demonstrated with applicability, and application to aquaculture industries.Major progress has been made in aquaculture genomics for dozens of fish and shellfish species including the development of genetic linkage maps, physical maps, microarrays, single nucleotide polymorphism (SNP) arrays, transcriptome databases and various stages of genome reference sequences. This paper provides a general review of the current status, challenges and future research needs of aquaculture genomics, genetics, and breeding, with a focus on major aquaculture species in the United States: catfish, rainbow trout, Atlantic salmon, tilapia, striped bass, oysters, and shrimp. While the overall research priorities and the practical goals are similar across various aquaculture species, the current status in each species should dictate the next priority areas within the species. This paper is an output of the USDA Workshop for Aquaculture Genomics, Genetics, and Breeding held in late March 2016 in Auburn, Alabama, with participants from all parts of the United States.

Stress of aquatic animals occurs due to physical and physiological disturbances in the aquatic environment or system when transportation, crowding, handling or changes of physical and chemical factors take place. There are three regulatory systems having a vital role in stress response: the neural, endocrine and immune systems. Fish exhibit multiple genomic and physiological responses to adjust the compensatory or adaptive mechanism that allows them to mitigate the stressors, maintain their haemostasis and survive. In this review, we describe multiple important genes that are associated with responses to environmental and husbandry stressors and that could be used as biomarkers of environmental and husbandry stressors in fish. The described environmental and husbandry stressors include salinity, temperature, hypoxia and hyperoxia, confinement, density and handling. The main role of stress response in aquatic animals is to compensate or adapt their biological systems and arrange the metabolism to afford the energy required by the stressor and a wide array of metabolic processes and pathways are involved. We summarized and discussed highly significant genes in several organs and tissues that are involved and active during this adaption process. The traditional stress biomarkers in some circumstances have some difficulties in interpretation of results and lead to tricky diagnosis and searching and understanding alternative tools is critical for aquaculture, fisheries and fish welfare. Using genomic tools to study the candidate genes associated with stress responses are often unique signatures or imprints of specific stressors and could determine early signs of stressors.

Retaining pedigree information and genetic diversity in each generation is essential but difficulty in selective breeding of aquaculture species. In this study, simulations and real data analysis were performed to examine the power of microsatellite markers in parentage determination of golden mandarin fish (Siniperca scherzeri). Simulations based on allele frequency data from the population of golden mandarin fish showed that the power of six loci to exclude false parents was higher than 95 % and that of seven loci over 97 %. When marker data from seven loci were combined, the accuracy of assignment to one true parental pair was up to 91.6 % with known parental and filial information. The marker panel tested in mixed families, 89.5 % of progeny was correctly assigned to their parental pairs. The mismatches caused by scoring errors at microsatellites loci were the major reason for the discrepancies between simulations and real data analysis. Taking these results into considerations, it was concluded that microsatellite markers can be used as a tool, alternative to physical tagging, to maintain pedigree information in selection programs of golden mandarin fish.

Much interest has been generated concerning the development of monosex male populations of bluegill Lepomis macrochirus due to their more rapid growth capacity relative to females. The methods involved to develop monosex population require a comprehensive understanding of the underlying basis of sex determination and gonadal function with the development of monosex male populations. In this study, effects of genotype by temperatures on sex determination, and sexual size dimorphism and growth were tested on two batches of fry from different geographic populations. In the first batch, sex ratios significantly deviated from 1:1 in 29 °C and 34 °C groups, in which a significantly higher proportion of males (70.64% and 66.67%) were found ( P P P > 0.05). The pooled sex ratios were compared and this showed that temperature had significant effects on sex ratios in the first batch of fish ( P P > 0.05). Through histological examination, intersex fish were identified in 17 °C and 34 °C groups. Rearing temperature strongly affected the growth of bluegill. Fish reared at the temperature of 29 °C performed best, followed by fish at 34 °C, 23 °C and 17 °C. No significant differences ( P > 0.05) were detected in the growth of juvenile bluegill (

Considering the divergent temperature habitats and morphological traits of four Percidae species: yellow perch (Perca flavescens), Eurasian perch (Perca fluviatilis), pike perch (Sander lucioperca), and ruffe (Gymnocephalus cernua), we stepped into the transcriptome level to discover genes and mechanisms that drive adaptation to different temperature environments and evolution in body shape. Based on 93,566 to 181,246 annotated unigenes of the four species, we identified 1,117 one-to-one orthologous genes and subsequently constructed the phylogenetic trees that are consistent with previous studies. Together with the tree, the ratios of nonsynonymous to synonymous substitutions presented decreased evolutionary rates from the D. rerio branch to the sub-branch clustered by P. flavescens and P. fluviatilis. The specific 93 fast-evolving genes and 57 positively selected genes in P. flavescens, compared with 22 shared fast-evolving genes among P. fluviatilis, G. cernua, and S. lucioperca, showed an intrinsic foundation that ensure its adaptation to the warmer Great Lakes and farther south, especially in functional terms like “Cul4-RING E3 ubiquitin ligase complex.” Meanwhile, the specific 78 fast-evolving genes and 41 positively selected genes in S. lucioperca drew a clear picture of how it evolved to a large and elongated body with camera-type eyes and muscle strength so that it could occupy the highest position in the food web. Overall, our results uncover genetic basis that support evolutionary adaptation of temperature and body shape in four Percid species, and could furthermore assist studies on environmental adaptation in fishes.

Cool Launch project is an important launch mode of submarine launched missile, the water-exit trajectory characteristic of the missile in launching process becomes to research focus. Model of three dimensional water-exit trajectory of submarine launched missile was built based on dynamic mesh technique and simulation operation was carried out to obtain the characteristics of water-exit trajectory & attitude. The method adopted in the establishment of the model and the result has provided references to the research of water-exit trajectory.

The unsteady hydrodynamic accurate calculation is the premise of submerged body trajectory design and maneuverability design. Calculation model of submerged body unsteady hydrodynamic with the movement in the longitudinal plane was established, which based on unsteady three-dimensional incompressible fluid dynamics theory. Variable speed translational and variable angular velocity of the pitching motion in the longitudinal plane of submerged body was achieved by dynamic mesh method. The unsteady hydrodynamic could be obtained by model under the premise of good quality grid by the results. Modeling methods can learn from other similar problems, which has engineering application value.

A novel vector field transform is proposed for digital images, which is inspired by the electro-static analogy. By introducing the factor of gray-scale difference into the repulsion vector between image points, the diffusing vector field is obtained by the transform. A new image segmentation method is then presented based on the diffusing vector field. The experimental results have proved the method’s effectiveness.

There is increasing evidence that temperature effects on sex ratio in fish species are ubiquitous. Temperature effects on sex ratio could be influenced by parent, strain, and population, whether in fish species with temperature-dependent sex determination or genetic sex determination plus temperature effects. In the present study, effects of genotype-temperature interactions on sex determination in bluegill sunfish were further investigated, based on our previous results, using four geographic strains: Hebron, Jones, Hocking, and Missouri. In the Hebron strain, the two higher-temperature treatment groups (24 °C and 32 °C) produced more males than the low-temperature treatment group (17 °C) from 6 days post-hatching (dph) to 90 dph. In contrast, the low-temperature treatment produced more males than the other two higher-temperature treatments in the Jones strain. No significant effects of temperature on sex ratio were detected in the other two strains. Our results from sex ratio variance in different treatment times suggest that the thermosensitive period of sex differentiation occurs prior to 40 dph. Our results further confirmed that genotype-temperature interactions influence sex determination in bluegill. Therefore, to significantly increase the proportion of males, which grow faster and larger than females, a consumer- and environment-friendly approach may be achieved through selection of temperature sensitivity in bluegill.

The current study aimed to develop a method to rapidly, sensitively and practically screen for the epidermal growth factor receptor (EGFR) T790M mutation. This method combines an allele-specific competitive blocker (ACB) with a TaqMan quantitative polymerase chain reaction (PCR) amplification refractory mutation system (ARMS) in a one-step reaction. Using a mimic of a human genomic DNA panel containing serially diluted mutant alleles, the performance efficacy of this method was assessed. Using this method, the EGFR T790M mutation was detected in tyrosine kinase inhibitor (TKI)-naive samples obtained from 27 non-small cell lung cancer (NSCLC) patients with EGFR-activating mutations. The association between de novo T790M mutations and the clinical benefit of EGFR-TKI treatment was also analysed. The sensitivity of this method was as low as 0.01%. In the samples from the 27 NSCLC patients, this method identified 6 mutant patients (22.2%), which was higher than the detection rate with scorpion ARMS (0.0%). No clinical variables were associated with the occurrence of a de novo T790M mutation. The median progression-free survival time in the TKI-naive patients with a T790M mutation was shorter that that of patients without the mutation, but the difference was not significant (3.2 vs. 19.5 months, respectively; P=0.256). The median overall survival time in the groups with or without T790M mutation also did not significantly differ (10 vs. 20 months, respectively; P=0.689). Overall, the ACB-ARMS PCR method could be useful for detecting the EGFR T790M mutation in clinical samples that contain only a small number of mutant alleles. The clinical significance of a de novo T790M mutation should be further investigated.

In this study, the gonadotropin-releasing hormone (GnRH) genes in spotted halibut were cloned and sequenced by isolating their cDNAs. The species expressed three molecular forms of GnRH in the brain: chicken-type GnRH-II (cGnRH-II), seabream-type GnRH (sbGnRH), and salmon-type GnRH (sGnRH). Phylogenetic analysis divided the molecular forms of GnRHs into three branches: cGnRH-II branch, sGnRH branch, and fish-specific GnRH branch. The spatial expression showed that they had the highest expression levels in the brain. cGnRH-II was exclusively detected in the brain, while sbGnRH had a global expression pattern in all examined organs. sGnRH was detected in the brain, pituitary, and ovary. The temporal changes of brain GnRH mRNA expression levels were examined during ovarian maturation and postspawning, and the serum steroid hormones and gonadosomatic index (GSI) were recorded. Amounts of sbGnRH mRNA substantially elevated (P < 0.05) during ovarian maturation, which concomitant with considerable elevation of GSI and serum steroids levels. On the contrary, neither sGnRH nor cGnRH-II mRNA levels showed significant changes during ovarian maturation in this study. These results suggested that these three GnRH genes are the important regulators for the differential expression of GnRH in spotted halibut, and would help us better understand the reproductive endocrine mechanism of spotted halibut.

Two selection methods, 1-stage selection (OSS) and 2-stage selection (TSS), for improving efficiency and profitability of selective breeding of yellow perch were evaluated, through examining the genetic and phenotypic parameters for BW of F(1) fish using microsatellite parentage assignment in this study. Approximately 94% of the sampled yellow perch progeny were assigned to single parental pairs using 8 microsatellite markers, which confirmed the applicability of the communal rearing technique in yellow perch breeding. Within OSS, the genetic correlation between 1-yr-BW and 2-yr-BW was high (0.98), indicating that the growth of yellow perch recorded at yr 1 could predict their growth for yr 2. Also mean family BW and family EBV for BW between yr 1 and 2 were found to be significantly correlated, suggesting yr 1 fast-growing yellow perch families continued to be the fast growing families in yr 2. Two-year random fish undergoing TSS were significantly heavier (P < 0.01) than those undergoing OSS. In addition, top males and females with TSS were heavier (P < 0.01) than those with OSS. Based on these results we concluded that the TSS was more desirable and effective for yellow perch breeding compared with OSS in terms of improving selection efficiency and reducing costs.

From 17 families, 400 fingerlings were evenly stocked into four replicates of each of five groups: single family from an Ohio strain, single family from a North Carolina strain, three families from the cross of five strains, 12 families from the cross of five strains and a combination of all 17 families. After rearing for 27 weeks, the progeny from the 17 families could be confidently assigned to their family of origin at the rate of 97.9%. The cross-bred multi-families (12-family and 3-family groups) from different strains gained significantly more weight than both single-family groups in separate tanks throughout most of the experiment (P 0.05). Both single families grew significantly faster in the all-family communal tanks than in single-family tanks by the end of the experiment (P

In the present study, the e⁄cacy of Letrozole, a potent nonsteroidal aromatase inhibitor (AI), on gonadal sex diierentiation and sex reversal was examined in bluegill sun¢sh (Lepomis macrochirus). In Experiment 1, using AI diet treatments (50, 150, 250 and 500 mg kg 1 ) from 30 to 90 days posthatch (dph), AI interrupted ovarian cavity formation at a dose of 500 mg kg 1 diet and one intersex ¢sh was identi¢ed in this group. The proportions of males in all the treated groups were signi¢cantly higher than those in the control group. In Experiment 2, using AI immersion treatments (250, 500 and 1000m gL 1 )d uring 30^ 50 dph, the treated groups of 500 and 1000m gL 1 produced signi¢cantly more males than the control and 250m gL 1 groups. Histological examination revealed no diierences in ovary or testis tissue between control and AI-treated ¢sh. There were no signi¢cant diierences detected in body weight and length among the AI treated and control groups (P40.05) for both experiments. The results from these two experiments suggest that inhibition of aromatase activity by AI could in£uence sex diierentiation in bluegill sun¢sh.

Genetic linkage maps were constructed for bluegill sunfish, Lepomis macrochirus, using AFLP in a F1 inter-population hybrid family based on a double-pseudo testcross strategy. Sixty-four primer combinations produced 4,010 loci, of which 222 maternal loci and 216 paternal loci segregated at a 1:1 Mendelian ratio, respectively. The female and male framework maps consisted of 176 and 177 markers ordered into 31 and 33 genetic linkage groups, spanning 1628.2 and 1525.3 cM, with an average marker spacing of 10.71 and 10.59 cM, respectively. Genome coverage was estimated to be 69.5 and 69.3% for the female and male framework maps, respectively. On the maternal genetic linkage map, the maximum length and marker number of the linkage groups were 122.9 cM and 14, respectively. For the paternal map, the maximum length and marker number of the linkage groups were 345.3 cM and 19, respectively, which were much greater than those on the maternal genetic linkage map. The other genetic linkage map parameters of the paternal genetic linkage map were similar to those in the maternal genetic linkage map. For both the female and male maps, the number of linkage groups was greater than the haploid chromosome number of bluegill (2n = 48), indicating some linkage groups may distribute on the same chromosome. This genetic linkage mapping is the first step toward to the QTL mapping of traits important to cultured breeding in bluegill.