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A high-density genetic map is essential for comparative genomic studies and fine mapping of QTL and can also facilitate genome sequence assembly. Here, a high density genetic map of Asian seabass was constructed with 3321 SNPs generated by sequencing 144 individuals in a F2 family. The length of the map was 1577.67 cM with an average marker interval of 0.52 cM. A high level of genomic synteny among Asian seabass, European seabass, Nile tilapia and stickleback was detected. Using this map, one genome-wide significant and five suggestive QTL for growth traits were detected in six linkage groups (i.e. LG4, LG5, LG11, LG13, LG14 and LG15). These QTL explained 10.5–16.0% of phenotypic variance. A candidate gene, ACOX1 within the significant QTL on LG5 was identified. The gene was differentially expressed between fast- and slow-growing Asian seabass. The high-density SNP-based map provides an important tool for fine mapping QTL in molecular breeding and comparative genome analysis.

Asian seabass (Lates calcarifer) is an important marine foodfish species in Southeast Asia and Australia. To facilitate a selective breeding program conducted in Singapore, we genotyped 772 Asian seabass individuals collected from five cultured stocks and four wild populations originating from Singapore, Australia, Malaysia, Thailand, Indonesia and Taiwan using 14 polymorphic microsatellites. A total of 210 alleles were detected at 14 loci across the nine populations. Cultured stocks showed much lower allelic and gene diversity (A = 3.57–8.21 alleles/locus, Ho = 0.52–0.66 and He = 0.47–0.74, respectively) than wild populations (A = 9.14–10.71 alleles/locus, Ho = 0.71–0.74 and He = 0.74–0.78, respectively). The wild population from Thailand showed the highest allele richness (AR = 8.50 alleles/locus), whereas one of the three cultured Australian stocks had the lowest one (3.57 alleles/locus). Populations from Southeast Asia were more diverse genetically (A = 13.28, AR = 10.23, Ho = 0.72 and He = 0.78) than those from Australia (7.0, 6.56, 0.59 and 0.64, respectively) and Taiwan (7.35, 7.35, 0.66 and 0.68, respectively). Nearly three quarter (73.3%) of 90 private alleles were detected in populations from Southeast Asia. Genetic differentiation among populations/stocks was statistically significant (FST = 0.124, RST = 0.159, P < 0.05). Phylogenetic analysis showed that stocks from Australia clustered into one group, while the samples from Southeast Asian and Taiwan formed another group. All these data suggest significant genetic differentiation between Australian and Southeast Asian populations/stocks, and Australian populations contain only part of genetic variation of Asian seabass, which should be taken into account in aquaculture of Asian seabass. A total of 549 individuals from the four wild populations in Southeast Asia are being used in a selective breeding program.

The aim of this study was to investigate the effect of the squamosamide derivative FLZ (N-2-(4-hydroxy-phenyl)-ethyl-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) on lipopolysaccharide (LPS)-induced inflammatory mediator production and the underlying mechanism in RAW264.7 macrophages.RAW264.7 cells were preincubated with non-toxic concentrations of compound FLZ (1, 5, and 10 micromol/L) for 30 min and then stimulated with 10 microg/L LPS. The production of nitric oxide (NO), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), and the activation of nuclear factor kappa-B (NF-kappaB) and mitogen-activated protein kinase (MAPK) pathways were examined.FLZ significantly inhibited the LPS-induced production of NO, as well as the expression of iNOS and COX-2 at both the RNA and the protein levels in RAW264.7 cells. The LPS-induced increase in the DNA binding activity of NF-kappaB and activator protein 1 (AP-1), the nuclear translocation of NF-kappaB p65, the degradation of the inhibitory kappaBalpha protein (IkappaBalpha) and the phosphorylation of IkappaBalpha, IkappaB kinase (IKK) alpha/beta, c-Jun NH(2)-terminal kinase (JNK) and p38 MAPKs were all suppressed by FLZ. However, the phosphorylation of extracellular signal-regulated kinase (ERK) was not affected. Further study revealed that FLZ inhibited the phosphorylation of transforming growth factor-beta (TGF-beta)-activated kinase 1 (TAK1), which is an upstream signaling molecule required for IKKalpha/beta, JNK and p38 activation.FLZ inhibited the LPS-induced production of inflammatory mediators at least partly through the downregulation of the TAK-IKK and TAK-JNK/p38MAPK pathways.

Alzheimer's disease (AD) is the most common neurodegenerative disorder in which neuroinflammation plays an important role. FLZ is a novel synthetic derivative of natural squamosamide. Previous studies demonstrated that FLZ had neuroprotective effects on AD models and showed strong anti-inflammatory property in Parkinson's disease models. However, whether the neuroprotective effects of FLZ on AD are associated with its anti-inflammatory property is still not fully elucidated. In this study, we aimed to investigate the ability of FLZ in modulating inflammation. The results showed that FLZ significantly improved memory deficits and alleviated neuronal damage as well as neuronal loss in the hippocampus of mice intracerebroventricular injected with lipopolysaccharide (LPS). Mechanistic studies revealed that the neuroprotective effects of FLZ were due to the suppression of neuroinflammation induced by LPS, as indicated by inactivation of astrocytes and microglia, reduced production of tumor necrosis factor-α, interleukin-1β, and nitric oxide, as well as decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase. The beneficial effects of FLZ on AD were further supported by the finding that FLZ attenuated β-amyloid production through inhibiting β-amyloid precursor protein cleaving enzyme 1 expression. These results suggested that anti-inflammatory agent could be useful for the treatment of AD.

In aquaculture species, maintaining pedigree information and genetic variation in each generation is essential, but very difficult. In this study, we used nine microsatellites to genotype 2,520 offspring from four independent full-factorial crosses (10 males × 10 females) of Asian seabass to reconstruct pedigree and monitor the change of genetic variations. In all four crosses, over 96.8% of the offspring could be assigned to their parents, indicating the high power of the nine microsatellites for parentage assignment. This study revealed several interesting results: (1). In all four crosses, the contribution of parents to offspring was significantly uneven, and some dominant breeding fishes (i.e. brooders) were found; (2). In two mass crosses where the brooders were carefully checked for reproductive status, a majority (≥ 90%) of brooders contributed to offspring, whereas in another two crosses, where the brooders were randomly picked without checking reproductive status, only a few brooders (40.0-45.0%) produced offspring; (3). Females had more problems in successful spawning compared to males; and (4). In the two crosses where a few brooders produced offspring, there was a substantial loss in allelic (24.1-34.3%) and gene (20.5-25.7%) diversities in offspring, while in the other two crosses, the majority of allelic (96.8-97.0%) and gene diversities (94.8-97.1%) were maintained. These observations suggest that a routine molecular parentage analysis is required to maintain both allelic and gene diversity in breeding Asian seabass.