一个可降解直链烷基苯磺酸盐的新种

本文鉴定了一株可完全降解直链烷基苯磺酸盐（Linear Alkylbenzene Sulphonate,简称LAS）的菌株GZ6。革兰氏染色阴性,细胞为杆状或短杆状,大小为0.5μm～0.8 μm×1.0μm～2.0 μm,其生长pH范围为pH6.0～10.0,最适生长pH为7.0,生长温度范围为4℃～40℃,最适生长温度为30℃。生化特征测定除过氧化氢酶、尿酶、精氨酸脱羧酶反应为阳性,其它均为阴性。可利用Chloridazon、安替比林（antipyrin）以及LAS等为碳源。不能利用大多数糖醇。醌组分以泛醌Q10为主。菌体脂肪酸主要为C18∶1、C16∶0及C16∶1。DNA中G+C mol％含量为7010。16S rRNA 序列分析表明菌株GZ6 与其亲缘关系最近的菌株Phenylobacterium immobile DSM1986T序列相似值为9749％,DNADNA杂交率为40%。菌株GZ6具极生鞭毛,可运动,两者在细胞形态有很大差异。故将菌株GZ6定为苯基杆菌属的新种可动苯基杆菌（Phenylobaterium mobile） GZ6。     

Protective effect of selenium against mercury-induced toxicity on hematological and biochemical parameters of Oreochromis niloticus

In this study, to identify mercury (Hg) toxicity and whether selenium (Se) has any role in alleviation of this toxicity, it was investigated the changes in hematological and serum biochemical parameters of Oreochromis niloticus. Fish were exposed to 0.01 and 0.1 mg/L Hg and 0.01 mg/L Hg + 0.1 mg/L Se and 0.1 mg/L Hg + 1.0 mg/L Se for 7 and 14 days. The exposure of O. niloticus to Hg alone resulted in decreases in red blood cell, white blood cell, hemoglobin, hematocrit values, and cholinesterase activity while it increased in alanine aminotransferase and aspartate aminotransferase activities and cortisol and glucose levels. Se, in combination with Hg, partially or totally caused an alleviation for the toxic effect of Hg on the above mentioned hematological and biochemical parameters. The results of our study showed that Se has a protective effect against toxicity induced by Hg.     

Exploration of polyacrylamide microplastics and evaluation of their toxicity on multiple parameters of Oreochromis niloticus

Due to the increased production of polyacrylamide microplastics in the environment impacting the adverse effects on aquatic organisms have become a global concern. The present study aimed to evaluate the toxicity of different concentrations (0.018, 0.03 0.09 g/1) of polyacrylamide microplastics on Oreochromis niloticus. Polyacrylamide microplastics were characterized by Fourier transform infrared and Raman spectroscopy. The FTIR technique revealed the spherical morphology and size range of polyacrylamide (0.1–0.4 mm) with 99 % purity. Raman Spectroscopy results showed peaks around (1100 cm^?1 and 1650 cm^?1) in gills, these peaks confirmed the presence of polyacrylamide microplastics in the gills of Oreochromis niloticus. Polyacrylamide microplastics significantly shortened the antioxidant enzymes (Catalase and Reduced glutathione) proceedings and the increase was observed in Malondialdehyde and Lipid peroxide levels in high-dose treated groups. Moreover, total protein contents were expressively increased, while other blood parameters (AST, ALP, ALT) were significantly decreased. Hemoglobin (g/dl), Erythrocyte (106/µl) and TLC (1x10⁹/l) levels were reduced significantly (p < 0.05) in high concentrations. The administration of polyacrylamide microplastics induced different histological changes in the gills, liver and intestine of O. niloticus. It was concluded that polyacrylamide microplastics are toxic agents having harmful effects on fish health.     

Effect of different stress factors on some physiological parameters of Nile tilapia (Oreochromis niloticus)

This study was conducted to determine the effect of different stress factors on some physiological measurements of Nile tilapia (Oreochromis niloticus).A total number of 160 Nile tilapia, the body weight ranging between 100 and 120 g, were exposed to three stress factors of hypoxia, overcrowding and starvation for different periods 24, 72 and 144 h. The results of cortisol level were 134.15, 144.27, 154.12 ng/ml and 140.18 ng/ml for control, hypoxia, overcrowding and starvation, respectively, while after 144 h did not show significant difference among treatments compared with control group. In contrast, the values of T₃ and T₄ observed reduction with significant difference that T₃ ranged between the highest value 122.12 ng/ml for control group to lowest value of starvation group 94.35, 93.81 and 88.46 ng/ml after 24, 72 and 144 h. Also, similar trend of results observed in T₄ and blood glucose among treatments. And the enzymatic activity of lactate dehydrogenise (LDH) increased in hypoxic group, while a significant reduction appeared in overcrowding and starved fish compared to control group. The pyruvate kinase (PK) activity decreased in hypoxic group but increased in other group.     

尼罗罗非鱼ZAP-70蛋白的原核表达、纯化及其多抗制备

[目的]构建尼罗罗非鱼ZAP-70原核表达载体,纯化其重组蛋白并制备多克隆抗体。[方法]采用无缝克隆技术构建尼罗罗非鱼ZAP-70重组表达载体,并转入大肠杆菌B21中诱导表达,将表达的ZAP-70蛋白免疫日本大耳兔得到多克隆抗体,采用Western Blotting和ELISA技术鉴定抗体的特异性和效价。[结果]成功构建原核表达重组质粒p ET-B2m-ZAP-70,诱导表达的重组蛋白分子量约为39 k Da,主要以包涵体的形式表达;获得效价为1∶512 000的多克隆抗血清,WB检测显示该抗体能够特异性的识别所表达的ZAP-70重组蛋白。[结论]尼罗罗非鱼ZAP-70重组质粒在大肠杆菌B21中高效表达,分子量约为39 k Da,该蛋白具有良好的免疫原性,为进一步探索ZAP-70在尼罗罗非鱼免疫系统中的功能奠定了基础。     

Nicotinamide Nucleotide Transhydrogenase (Nnt) Links the Substrate Requirement in Brain Mitochondria for Hydrogen Peroxide Removal to the Thioredoxin/Peroxiredoxin (Trx/Prx) System

Mitochondrial reactive oxygen species are implicated in the etiology of multiple neurodegenerative diseases, including Parkinson disease. Mitochondria are known to be net producers of ROS, but recently we have shown that brain mitochondria can consume mitochondrial hydrogen peroxide (H₂O₂) in a respiration-dependent manner predominantly by the thioredoxin/peroxiredoxin system. Here, we sought to determine the mechanism linking mitochondrial respiration with H₂O₂ catabolism in brain mitochondria and dopaminergic cells. We hypothesized that nicotinamide nucleotide transhydrogenase (Nnt), which utilizes the proton gradient to generate NADPH from NADH and NADP⁺, provides the link between mitochondrial respiration and H₂O₂ detoxification through the thioredoxin/peroxiredoxin system. Pharmacological inhibition of Nnt in isolated brain mitochondria significantly decreased their ability to consume H₂O₂ in the presence, but not absence, of respiration substrates. Nnt inhibition in liver mitochondria, which do not require substrates to detoxify H₂O₂, had no effect. Pharmacological inhibition or lentiviral knockdown of Nnt in N27 dopaminergic cells (a) decreased H₂O₂ catabolism, (b) decreased NADPH and increased NADP⁺ levels, and (c) decreased basal, spare, and maximal mitochondrial oxygen consumption rates. Nnt-deficient cells possessed higher levels of oxidized mitochondrial Prx, which rendered them more susceptible to steady-state increases in H₂O₂ and cell death following exposure to subtoxic levels of paraquat. These data implicate Nnt as the critical link between the metabolic and H₂O₂ antioxidant function in brain mitochondria and suggests Nnt as a potential therapeutic target to improve the redox balance in conditions of oxidative stress associated with neurodegenerative diseases.     

Translocation of heme oxygenase-1 to mitochondria is a novel cytoprotective mechanism against non-steroidal anti-inflammatory drug-induced mitochondrial oxidative stress, apoptosis, and gastric mucosal injury

The mechanism of action of heme oxygenase-1 (HO-1) in mitochondrial oxidative stress (MOS)-mediated apoptotic tissue injury was investigated. MOS-mediated gastric mucosal apoptosis and injury were introduced in rat by indomethacin, a non-steroidal anti-inflammatory drug. Here, we report that HO-1 was not only induced but also translocated to mitochondria during gastric mucosal injury to favor repair mechanisms. Furthermore, mitochondrial translocation of HO-1 resulted in the prevention of MOS and mitochondrial pathology as evident from the restoration of the complex I-driven mitochondrial respiratory control ratio and transmembrane potential. Mitochondrial translocation of HO-1 also resulted in time-dependent inhibition of apoptosis. We searched for the plausible mechanisms responsible for HO-1 induction and mitochondrial localization. Free heme, the substrate for HO-1, was increased inside mitochondria during gastric injury, and mitochondrial entry of HO-1 decreased intramitochondrial free heme content, suggesting that a purpose of mitochondrial translocation of HO-1 is to detoxify accumulated heme. Heme may activate nuclear translocation of NF-E2-related factor 2 to induce HO-1 through reactive oxygen species generation. Electrophoretic mobility shift assay and chromatin immunoprecipitation studies indicated nuclear translocation of NF-E2-related factor 2 and its binding to HO-1 promoter to induce HO-1 expression during gastric injury. Inhibition of HO-1 by zinc protoporphyrin aggravated the mucosal injury and delayed healing. Zinc protoporphyrin further reduced the respiratory control ratio and transmembrane potential and enhanced MOS and apoptosis. In contrast, induction of HO-1 by cobalt protoporphyrin reduced MOS, corrected mitochondrial dysfunctions, and prevented apoptosis and gastric injury. Thus, induction and mitochondrial localization of HO-1 are a novel cytoprotective mechanism against MOS-mediated apoptotic tissue injury.     

Effects of isoeugenol on oxidative stress pathways in normal and streptozotocin-induced diabetic rats.

Because some complications of diabetes mellitus may result from oxidative damage, we investigated the effects of subacute treatment (10mg/kg/day, intraperitoneal [ip], for 14 days) with the antioxidant isoeugenol on the oxidant defense system in normal and 30-day streptozotocin-induced diabetic Sprague-Dawley rats. Liver, kidney, brain, and heart were assayed for degree of lipid peroxidation, reduced and oxidized glutathione content, and activities of the free radical-detoxifying enzymes catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. All tissues from diabetic animals exhibited disturbances in antioxidant defense when compared with normal controls. Treatment with isoeugenol reversed diabetic effects on hepatic glutathione peroxidase activity and on oxidized glutathione concentration in brain. Treatment with the lipophilic compound isoeugenol also decreased lipid peroxidation in both liver and heart of normal animals and decreased hepatic oxidized glutathione content in both normal and diabetic rats. Some effects of isoeugenol treatment, such as decreased activity of hepatic superoxide dismutase and glutathione reductase in diabetic rats, were unrelated to the oxidative effects of diabetes. In heart of diabetic animals, isoeugenol treatment resulted in an exacerbation of already elevated activities of catalase. These results indicate that isoeugenol therapy may not reverse diabetic oxidative stress in an overall sense.     

4-Methylene-2-octyl-5-oxotetrahydrofuran-3-carboxylic Acid (C75), an Inhibitor of Fatty-acid Synthase,Suppresses the Mitochondrial Fatty Acid Synthesis Pathway and Impairs Mitochondrial Function

4-Methylene-2-octyl-5-oxotetrahydrofuran-3-carboxylic acid (C75) is a synthetic fatty-acid synthase (FASN) inhibitor with potential therapeutic effects in several cancer models. Human mitochondrial β-ketoacyl-acyl carrier protein synthase (HsmtKAS) is a key enzyme in the newly discovered mitochondrial fatty acid synthesis pathway that can produce the substrate for lipoic acid (LA) synthesis. HsmtKAS shares conserved catalytic domains with FASN, which are responsible for binding to C75. In our study, we explored the possible effect of C75 on HsmtKAS and mitochondrial function. C75 treatment decreased LA content, impaired mitochondrial function, increased reactive oxygen species content, and reduced cell viability. HsmtKAS but not FASN knockdown had an effect that was similar to C75 treatment. In addition, an LA supplement efficiently inhibited C75-induced mitochondrial dysfunction and oxidative stress. Overexpression of HsmtKAS showed cellular protection against low dose C75 addition, whereas there was no protective effect upon high dose C75 addition. In summary, the mitochondrial fatty acid synthesis pathway has a vital role in mitochondrial function. Besides FASN, C75 might also inhibit HsmtKAS, thereby reducing LA production, impairing mitochondrial function, and potentially having toxic effects. LA supplements sufficiently ameliorated the toxicity of C75, showing that a combination of C75 and LA may be a reliable cancer treatment.     

Complete Genome Sequence of Streptococcus agalactiae ZQ0910, a Pathogen Causing Meningoencephalitis in the GIFT Strain of Nile Tilapia (Oreochromis niloticus)

Streptococcus agalactiae (group B streptococcus [GBS]) is a pathogen that causes meningoencephalitis in Nile tilapia (Oreochromis niloticus). Here, we reported the complete genome sequence of S. agalactiae strain ZQ0910, which was isolated from the GIFT strain of Nile tilapia in Guangdong, China.     

Synergistic Effects of Selenium Nanoparticles and Vitamin E on Growth,Immune-Related Gene Expression,and Regulation of Antioxidant Status of Nile Tilapia (Oreochromis niloticus)

Biological Trace Element Research - The present study was conducted to investigate the effects of nano-selenium (Nano Se) or/and vitamin E (VE) on growth performance, blood health, intestinal...     

碱度胁迫对尼罗罗非鱼鳃离子细胞形态以及鳃、肾和肠中HCO3-转运因子的影响

采用扫描电镜观察了不同碱度(0、2、4 g/L Na HCO_3)胁迫对尼罗罗非鱼(Oreochromis niloticus)鳃离子细胞形态变化的影响,并采用免疫组化技术观察了鳃、肾、肠中4个HCO_3~-转运因子碳酸酐酶(CAⅡ、CAⅣ)、碳酸氢钠协同转运载体(SLC4A4)、Cl~-/HCO_3~-离子交换体(SLC26A6)的阳性反应变化。扫描电镜结果表明,鳃离子细胞分布在鳃小片基部。根据其表面开孔形状和尺寸,可分为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型4种亚型,各亚型离子细胞的开孔尺寸随碱度胁迫强度增高呈正比增大,Ⅲ型离子细胞开孔尺寸变化最明显(P0.01);离子细胞总数目也随碱度升高而增加,Ⅲ型离子细胞数目上升最为显著(P0.01)。免疫组化结果表明,在淡水、碱水组中,CAⅡ、CAⅣ、SLC4A4、SLC26A6在鳃小片基部和肾中均有阳性反应,且随着碱度升高,阳性反应增强,但在肠道中未观察到阳性反应。本研究结果初步表明,尼罗罗非鱼可通过鳃离子细胞形态和数量调节适应碱度变化,鳃和肾为主要应答调节器官。     

Interacting effects of water temperature and dietary protein level on hematological parameters in Nile tilapia juveniles,Oreochromis niloticus (L.) and mortality under Streptococcus iniae infection

Based on central composite rotatable experimental design and response surface method, the interacting effects of temperature (20 °C–34 °C) and dietary protein level (25%–50%) on hematological parameters including red blood cell (RBC), white blood cell (WBC) and hemoglobin (Hb) of juvenile Oreochromis niloticus were studied under laboratory conditions. The experiment lasted for 7 weeks. After the feeding trial, fish were challenged with Streptococcus iniae and mortality was recorded for within 8 days. Results showed that the linear and quadratic effects of temperature on RBC, WBC and Hb were highly significant (P < 0.01). When the dietary protein level was 25%–50%, the RBC, WBC and Hb were increased firstly and then decreased, but the linear and quadratic effects of protein level were insignificant (P > 0.05). The interacting effects of temperature and protein level on RBC and Hb were significant (P < 0.05). The regression equations of RBC, WBC and Hb toward the two factors of interest were established, with the coefficients of determination being 0.870, 0.836 and 0.881, respectively (P < 0.01). These equations could be used for prediction in practice. After the challenge, the mortalities for the combinations of 22.1 °C/28.7% and 20.0 °C/37.5% were significantly higher than 27.0 °C/37.5% (P < 0.05). The optimal temperature/dietary protein level combination was obtained at 27.9 °C/38.1% at which the lowest mortality (13.76%) was attained. This value was close to the optimal temperature/dietary protein level combination (29.4 °C/41.9%) for the greatest levels of RBC (2.560 × 10⁶ μL^?1), WBC (270.648 × 10³ μL^?1) and Hb (92.851 g L^?1). The results of this study indicated that preferred temperature/dietary protein level combination might strengthen the non-specific immunity and reduce susceptibility to S. iniae.     

Dietary sodium butyrate ameliorated the blood stress biomarkers,heat shock proteins,and immune response of Nile tilapia (Oreochromis niloticus) exposed to heat stress

The present study investigated the effects of sodium butyrate (SB) on the growth performance, histomorphology, immune response, and stress related markers of Nile tilapia subjected to heat stress. SB was incorporated at 0, 0.5, 1, 1.5, and 2 g per kg diet and fed to fish for 8 weeks. The obtained results revealed significantly improved growth performance with a decreased feed conversion ratio in the fish fed SB (P < 0.05). In the anterior, middle, and distal parts of the intestine, villus length and width and internal villi distance as well as the number of goblet cells were increased in the fish fed SB (P < 0.05). The blood total protein, hemoglobin, and white and red blood cell counts showed a significant quadratic influence (P < 0.05). The survival rate for Nile tilapia exposed to heat stress for 48 h revealed that the SB fed groups had noticeably higher survival rates. Dietary SB significantly increased the phagocytic index and lysozyme and phagocytic activities both before and after heat stress (P < 0.05). After heat stress, blood glucose decreased significantly with SB feeding at 0.5, 1, or 1.5 g per kg diet, while cortisol was reduced in fish fed 1.5 or 2 g per kg diet (P < 0.05). Additionally, in fish fed SB, superoxide dismutase (SOD), catalase, and glutathione peroxidase activities were significantly increased both before and after heat stress, while malondialdehyde was decreased by SB feeding (P < 0.05). Liver heat shock protein 70 and SOD gene expression were significantly upregulated in fish fed on SB at 1 g per kg diet (P < 0.05). Thus, supplementation with SB at 1–2 g per kg diet can be used effectively in tilapia diets for improving growth, feed efficiency, and immune response as well as for tolerance to heat stress.     

Physical mapping of the brain and ovarian aromatase genes in the Nile Tilapia,Oreochromis niloticus,by fluorescence in situ hybridization

Cytochrome P450-aromatase enzyme (CYP19), which catalyses the conversion of androgens to oestrogens, is critical in ovarian differentiation and hence in the sex differentiation pathways of non-mammalian vertebrates. As in other fish species, distinct ovarian and brain aromatase genes have been identified in the Nile Tilapia, Oreochromis niloticus. Here we demonstrate by in situ hybridization that the two aromatase genes of this species are present on different chromosomes and that neither are located on the sex chromosomes. Hence, the aromatase genes are not the primary sex determination genes in O. niloticus.     

Sperm quality analysis in XX, XY and YY males of the Nile tilapia (Oreochromis niloticus)

In Nile tilapia (Oreochromis niloticus), individuals with atypical sexual genotype are commonly used in farming (use of YY males to produce all-male offspring), but they also constitute major tools to study sex determinism mechanisms. In other species, sexual genotype and sex reversal procedures affect different aspects of biology, such as growth, behavior and reproductive success. The aim of this study was to assess the influence of sexual genotype on sperm quality in Nile tilapia. Milt characteristics were compared in XX (sex-reversed), XY and YY males in terms of gonadosomatic index, sperm count, sperm motility and duration of sperm motility. Sperm motility was measured by computer-assisted sperm analysis (CASA) quantifying several parameters: total motility, progressive motility, curvilinear velocity, straight line velocity, average path velocity and linearity. None of the sperm traits measured significantly differed between the three genotypes. Mean values of gonadosomatic index, sperm concentration and sperm motility duration of XX, XY and YY males, respectively ranged from 0.92 to 1.33%, from 1.69 to 2.22 ×10⁹ cells mL⁻¹ and from 18′04″ to 27′32″. Mean values of total motility and curvilinear velocity 1 min after sperm activation, respectively ranged from 53 to 58% and from 71 to 76 μm s⁻¹ for the three genotypes. After 3 min of activity, all the sperm motility and velocity parameters dropped by half and continued to slowly decrease thereafter. Seven min after activation, only 9 to 13% of spermatozoa were still progressive. Our results prove that neither sexual genotype nor hormonal sex reversal treatments affect sperm quality in male Nile tilapias with atypical sexual genotype.     

Molecular basis and structural insight of vascular K(ATP) channel gating by S-glutathionylation

The vascular ATP-sensitive K(+) (K(ATP)) channel is targeted by a variety of vasoactive substances, playing an important role in vascular tone regulation. Our recent studies indicate that the vascular K(ATP) channel is inhibited in oxidative stress via S-glutathionylation. Here we show evidence for the molecular basis of the S-glutathionylation and its structural impact on channel gating. By comparing the oxidant responses of the Kir6.1/SUR2B channel with the Kir6.2/SUR2B channel, we found that the Kir6.1 subunit was responsible for oxidant sensitivity. Oxidant screening of Kir6.1-Kir6.2 chimeras demonstrated that the N terminus and transmembrane domains of Kir6.1 were crucial. Systematic mutational analysis revealed three cysteine residues in these domains: Cys(43), Cys(120), and Cys(176). Among them, Cys(176) was prominent, contributing to >80% of the oxidant sensitivity. The Kir6.1-C176A/SUR2B mutant channel, however, remained sensitive to both channel opener and inhibitor, which indicated that Cys(176) is not a general gating site in Kir6.1, in contrast to its counterpart (Cys(166)) in Kir6.2. A protein pull-down assay with biotinylated glutathione ethyl ester showed that mutation of Cys(176) impaired oxidant-induced incorporation of glutathione (GSH) into the Kir6.1 subunit. In contrast to Cys(176), Cys(43) had only a modest contribution to S-glutathionylation, and Cys(120) was modulated by extracellular oxidants but not intracellular GSSG. Simulation modeling of Kir6.1 S-glutathionylation suggested that after incorporation to residue 176, the GSH moiety occupied a space between the slide helix and two transmembrane helices. This prevented the inner transmembrane helix from undergoing conformational changes necessary for channel gating, retaining the channel in its closed state.