Search

The Centropristis striata is an important economically marine fish and facing a serious threat from various pathogens. Edwardsiella piscicida is one of the fish pathogens that seriously infect cultured and wild fish species. To understand the molecular immune mechanisms underlying the response to E. piscicida, a comparative gene transcription analysis was performed through RNA‐Seq technology. The low‐quality sequences were excluded, and the high‐quality sequences were assembled into a total of 60,759 contigs with an average length of 988.95 bp. A gene ontology (GO) analysis was employed to classify 5744 genes according to three major functional categories: molecular function, cellular component and biological process. A total of 19,918 genes were successfully annotated into 26 functional categories according to the clusters of orthologous groups (COG) classification. Furthermore, 15,006 genes were classified into 332 KEGG pathways. The q‐value was introduced to estimate 5109 genes significantly differentially expressed which includes 1781 up‐regulated genes and 3328 down‐regulated genes. The differentially expressed genes were involved in the major immune‐related pathways which refer to the pathogen recognition, inflammation, Toll‐like receptor and chemokine signalling pathways. Moreover, 24,487 potential simple sequence repeats (SSRs) and 193,760 candidate single nucleotide polymorphisms (SNPs) were detected and identified in the C. striata liver transcriptome. This work not only provides a valuable resource for further understanding of the antibacterial molecular mechanism of C. striata but also contributes to facilitate future studies on gene expression and functional genomics. [ABSTRACT FROM AUTHOR]

Abstract The current study examined effects of waterborne cadmium (Cd) at environmental relevant concentrations (0, 2.5 and 5 μg/L) on growth, survival, histology, ultrastructure, metal homeostasis, and antioxidant responses in female zebrafish from embryos to sexually maturity for 15 weeks. Growth and survival rate were not significantly affected by Cd exposure. There were no significant changes in ultrastructure of cellular organelles, reactive oxygen species (ROS) levels, lipid peroxidation (LPO) in liver. However, Cd exposure increased Cd and lipid accumulation, reduced contents of zinc, copper and reduced glutathione (GSH), and down-regulated activity of copper/zinc-superoxide dismutase (Cu/Zn-SOD) in liver of zebrafish. Contrarily, the mRNA and activity levels of catalase (CAT), the mRNA levels of Cu/Zn-SOD, and the mRNA and protein levels of metallothioneins (MTs) were up-regulated. The transcriptional regulation of Cu and Zn transporters might be a vital mechanism by which fish slow the Zn and Cu uptake. Taken together, our data demonstrated that long-term and low-dose Cd induced adaptive responses with interlinked compensatory mechanism, which may protect fish against oxidative stress. Highlights • A life cycle toxic assessment of cadmium was examined in fish. • Adaptive responses towards oxidative stress were found in zebrafish exposed to Cd. • Compensatory responses towards metal homeostasis and antioxidant system were demonstrated. • Several negative feedback loops were found to maintain ROS homeostasis. [ABSTRACT FROM AUTHOR]

Amphioxus occupies a transitional position between invertebrates and vertebrates and is therefore a promising laboratory model animal. As a powerful molecular marker in population genetics studies, microsatellite DNA is required for both the investigation of genetic diversity of a wild amphioxus population and strain breeding of laboratory cultured amphioxus. In the present study, we constructed a microsatellite-enriched DNA library of amphioxus Branchiostoma belcheri to develop this molecular marker. After screening the library and combining it with the data obtained from a public database, we successfully developed 21 pair of primers that could effectively amplify the microsatellite loci of amphioxus. Of those primer pairs, seven were in deviation of Hardy–Weinberg equilibrium, mostly caused by null alleles. The others had no linkage disequilibrium, indicating they are applicable for the genetic studies. Using those primer pairs, we further detected the genetic diversity of the wild amphioxus population in Xiamen waters. The results revealed that the number of alleles of each microsatellite locus was between three and 18 in the population, and observed and expected heterozygosities of the loci ranged from 0.415 to 0.947 and from 0.300 to 1.000, indicating very high genetic diversity of the population. [ABSTRACT FROM AUTHOR]

Abstract Carnitine palmitoyltransferase 1 (CPT1) plays an essential role in maintaining energy supply via fatty acid oxidation, especially under fasting. In this study, the complete cDNA sequence of cpt1a was cloned from liver of large yellow croaker (Larimichthys crocea), with an open reading frame of 2319 bp encoding a protein of 772 amino acids. Bioinformatics analysis predicted the presence of conserved functional motifs and amino acid residues. The highest mRNA expression of cpt1a was observed in the liver. Phylogenetic tree clearly shows that CPT1A protein is a homologue of mammalian CPT1A. Recombinant protein rCPT1A showed catalytic activity, with Michaelis constant (km) (≈1.38 mM) and maximal reaction rates (Vmax) for carnitine (≈12.66 nmols/min/mg protein). The cpt1a mRNA expression dramatically increased and CPT1 activity remained unchanged after fasting. Fasting did not significantly change Vmax and free carnitine (FC) content in liver. Interestingly, catalytic efficiency (Vmax/Km) and FC/Km increased in fish fasted for 4 days, implying FC contents might be enough to ensure the optimal fatty acid oxidation. Contrarily, both indicators declined when fish fasted for 12 days. The present results demonstrated cpt1a has a biological function and showed that the transcriptional and kinetic regulation of CPT1 during fasting, emphasizing that fasting-induced fatty acid oxidation depends on changes in kinetic properties instead of CPT1 activity and transcription. Graphical abstract Unlabelled Image Highlights • A function of CPT1A was firstly demonstrated in fish by a yeast expression system. • Fasting affected CPT1A expression, Km for carnitine, and catalytic efficiency. • Short- and long-term fasting differently affected catalytic efficiency by changing Km. • Duration of fasting should be carefully considered when using it to reduce lipid content. [ABSTRACT FROM AUTHOR]

Certain light emitting diodes (LEDs) have become popular in fish farming beacause of a promoting effect on growth and reproduction. However, little information is available on innate immune responses in related tissues under LEDs conditions. The present study assessed the effects of a white fluorescent bulb (the control) and two different light-emitting diodes (LEDs: blue, LDB, peak at 450 nm; red, LDR, 630 nm) on growth and innate immune responses in the serum, liver and ovary of zebrafish for 8 weeks. LDB significantly enhanced specific growth rate (SGR), food intake (FI), and serum globulin levels. In contrast, LDR sharply inhibited SGR, FI, and the levels of albumin and globulin. Under LDB condition, there was an increase in protein levels of alkaline phophatase (AKP) and protein and activity levels of lysozyme (LZM) in the liver, and the levels of mRNA, protein, and activity of LZM in the ovary. Under LDR condition, LZM was dramatically down-regulated at mRNA, protein and activity levels in the ovary, suggesting that LZM was regulated at a transcriptional level. In the liver of the LDR group, though AKP mRNA levels sharply increased, its protein and activity levels significantly declined, indicating that AKP was regulated at translational level. Furthermore, a positive correlation between transcription factor NF-κB RelA mRNA levels and expression levels of AKP and LZM was observed in the liver and ovary, implying a transcriptional regulation of NF-κB RelA. In conclusion, the present study demonstrated a positive effect of LDB and negative effect of LDR on fish growth and innate immune responses, possibly associated with modifications at transcriptional, translational, and post-translational levels, and the transcriptional regulation of the NF-κB signaling molecule. [ABSTRACT FROM AUTHOR]

Based on the same toxic level of 0.6% LC 50 for 96-h and the severe situation of water pollution, we compared effects of chronic Zn (180 μg L −1 ) and Cd exposures (30 μg L −1 ) on growth, survival, histology, ultrastructure, and oxidative stress in the liver of zebrafish for 5 weeks. Growth performance and survival rate remained relatively constant under Zn stress, but was reduced under Cd exposure. Cd exposure also induced severe pyknotic nuclei, evident ultrastructure damage, and considerable lipid inclusions in the hepatocytes. However, these phenomena were not pronounced under Zn exposure. The negative effects caused by Cd may be explained by an increase in hepatic oxidative damage, as reflected by the enhanced levels of lipid peroxidation (LPO) and protein carbonylation (PC). The reduced activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) may result in the enhanced hepatic oxidative damage, though the mRNA and protein levels of both genes increased and remained unchanged respectively. On the contrary, Zn up-regulated the levels of mRNA, protein and activity of Cu/Zn-SOD, which may contribute to the decreased LPO levels. Nonetheless, the sharply up-regulated mRNA levels of CAT did not induce an increase in the protein and activity levels of CAT under Zn stress. Furthermore, transcription factor NF-E2-related factor 2 (Nrf2) expression parelleled with its target genes, suggesting that Nrf2 is required for the protracted induction of antioxidant genes. In conclusion, our data demonstrated that essential and non-essential metals induced some differences in oxidative damage in fish. The differences were not caused by the transcriptional level of related genes but depended on post-transcriptional modifications. [ABSTRACT FROM AUTHOR]

Objective: To analysis the effects of Talpha1 on the immune effector molecules in mouse immune system., Methods: Sixty five BABL/c mice were divided into four groups: CsA group (n=20), Talpha1 group (n= 20), CsA+Talpha1 group (n=20) and control group (n=5). In the 3 experimental groups, 10 mg/kg CsA, 400 microg/ kg Talpha1, 10 mg/kg CsA+400 microg/kg Talpha1 were respectively administrated by intraperitoneal injection daily. Luminex was performed for cytokine detection at 1 d, 7 d, 14 d, 21 d day after the above treatments. Lymphocyte culture was prepared with the mouse spleen suspension, and then treated with 0. 25 mg/mL CsA, 10 microg/mL Talpha1 or 0.25 mg/mL CsA+10 microg/mL Talpha1 in vitro, respectively. Three days later, OD values of each treated lymphocyte culture and several cytokines in the culture were measured., Results: Compared with other groups, CsA+Talpha1 group had significant lower IL-1alpha, IL-2, IL-6, IL-17, and significant higher IL-10 at 1 d, 7 d, 14 d, 21 d after the treatments (P < 0.05). Three days after the culture, OD value in the control group was significantly higher than that in Talppha1 group, CsA group, and CsA+ Talpha1 group (P < 0.05). IL-1alpa and IL-6 in the control group were significantly higher than those in the experiment groups (P < 0.05), while IL-10 in the control group was significantly lower than that in the experiment groups (P < 0.05). IL-2 and IL-17 were similar., Conclusion: Talpha1 show regulatory effect on the immune effector molecules which could promote Th1 cells transforming to Th2 cells.

One general requirement of individual laboratory animals is that they have known genetic backgrounds. However, ensuring such genetic similarity is difficult, and can be facilitated by breeding a full strain for experimentation. To this end, the authors bred 34 full-sib families of amphioxus larvae/embryos. Due to the high mortality of the embryos and larvae, only seven full-sib families of juvenile amphioxus Branchiostoma japonicum were obtained. Among them, the highest and lowest survival ratios were 32.4% and 1.67%, respectively, whereas the shortest metamorphosis and longest larva duration were 24 d and 42 d, respectively. These results demonstrate the feasibility of establishing full-sib families of amphioxus, and provide fundamental data needed for the future breeding of amphioxus strains.

Endogenous green fluorescent proteins (GFPs) have recently been found in amphioxus, where different characteristics of light production in different development stages and between different individuals have manifested. We identified the GFP genes in an amphioxus species Branchiostoma belcheri and monitored real time fluorescence signals of GFPs during different developmental stages to provide an insight on the GFP function in amphioxus. We found there are at least 12 endogenous GFP genes in amphioxus genome, and fluorescent expression changes in body position during different developmental stages. Additionally, GFP expression after metamorphosis development differed significantly among different amphioxus individuals, suggesting that there are multiple GFP homologous genes responsible for fluorescent expression. Expression levels of these genes varied significantly during different developmental stages, indicating that different GFP genes may have their unique functions in the development of amphioxus during specific phases of growth.

Amphioxus (lancelet) is an important model animal in the field of Evo-Devo study. However, the specimens for laboratorial experiments are usually sampled directly from the field. Thus, it is necessary to correctly identify species and evaluate the genetic diversity of geographic populations. In the present investigation, we amplified and sequenced COX I gene of amphioxus collected from various localities of the West Pacific Ocean and downloaded all available sequences of the gene from NCBI. Based on those sequences data, we constructed NJ tree to decide the taxonomic status of those amphioxus and performed AMOVA analysis to estimate genetic diversities among geographic populations and individuals. The current results supported the validity of the three amphioxus species, Branchiostoma malayanum, B. belcheri and B. japonicum. We also proposed that some amphioxus species names recorded in NCBI sequence database might be inaccurate. Genetic analysis on the geographic populations of amphioxus species suggested that each examined amphioxus species have a high level of genetic diversity. However, the genetic divergences among geographic populations of the same species are indetectable, indicating a frequent gene flow among them.