Breeding of XX Females( XX ♀),YY Physiological Females( YY♀),YY Super-males( YY♂ ) of Pure-line Yellow Catfish( Pelteobagrus fulvidraco Richardson)

Mature wild-type yellow catfish( Pelteobagrus fulvidraco Richardson) individuals with excellent traits have been screened from the Yangtze River as broodstock to establish the germplasm bank of pure-line yellow catfish by artificial gynogenesis technique and hormonal sex reversal method. Based on pure lines of yellow catfish,super-males and physiological females of yellow catfish were selected by GMT technique,hormonal sex reversal method and test-crossing to establish the germplasm bank of YY physiological females( YY♀). The propagation system of male yellow catfish( XY♂) was established based on the combination of super-males( YY♂) and pure-line female( XX♀) for large-scale production of pure-line yellow catfish males,which effectively overcome the disadvantages in the production of common fingerlings and male fingerlings using low-grade fish with slow growth and small size at the bottom of the fish grader as broodfish,such as progeny germplasm degeneration,loss of growth vigor and reduction of breeding benefits. The technical route of breeding pure-line YY physiological females( YY♀) and YY super-males( YY♂) laid the foundation for large-scale production of environmentally friendly yellow catfish males with pure germplasm and strong stress resistance,and provided an efficient,stable,healthy,environmentally friendly,energy-saving and income-increasing approach for sustainable development of yellow catfish breeding industry.

RHOPORHYNCHUS LINI N.G.N.SP.(BUCEPHALIDAE: BUCEPHALINAE) FROM THE SWIM BLADDER OF YELLOW CATFISH, PSEUDOBAGRUS FULVIDRACO

This paper describes and discuases a new bucephalid species, Rhoporhynchus lini,from the swim bladder of yellow catfish, Pseudobagrous fulvidraco, for Nanhai County of GuangdngProvince in China. lt is chimterized driuly by its wide flat foliate body, largr size, degeneratedrhynchus, voldrinous saccular intestine, dendrihc vitellaria, short uterus, limited locality of the repro-ductive organs and site of infechon in fish swim bladder. It is certainly allocated to the subfamily Bu-cephalinae according to its relative locallty of oveq and testes (ovary pretesticular). But it differs evident-ly from the species in all other genera of the subfamily. Therefore, a new genus, Rhoporhynchus, iserected with R. lini as the type species.

The probiotic effects of host-associated Bacillus velezensis in diets for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂)

This study was to evaluate the potential of a host-associated Bacillus velezensis as a probiotic for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂).Diets(B0 to B5)containing 0,0.90×10^(8),0.80×109,0.85×10^(10),0.90×10^(11),0.83×10^(12)CFU/kg B.velezensis YFI-E109 were fed to the fish with initial weight(3.07±0.08 g)in a recirculating aquaculture system for six weeks with three replicates,respectively.Probiotic effects were analyzed based on growth,body composition,liver and gut morphology,gut microbiome,and liver metabolome.Analysis of the bacterial genome has shown that the most abundant genes in B.velezensis YFI-E109 were distributed in carbohydrate and amino acid metabolism.Fish in groups B3 and B4 had better growth performance,and higher intestinal amylase(AMS)and lipase(LPS)activities compared with other groups(P<0.05).Fish in groups B0 and B5 showed significant liver damage,while this status improved in group B3.The liver malondialdehyde(MDA)content in group B3 was lower than that in other groups(P<0.05).The abundance of Mycoplasma,Ralstonia and Acinetobacter was significantly reduced in B3 and B5 compared to B0.The amino acid and carbohydrate metabolism pathways were enriched in group B3 compared with group B0.In conclusion,dietary B.velezensis YFI-E109 supplementation has the potential to improve growth,liver metabolism,and liver and gut health,and reshape the gut microbiome of hybrid yellow catfish.Excessive B.velezensis YFI-E109 reduced the prebiotic effects.The recommended dietary supplementation of B.velezensis YFI-E109 is 0.31×10^(10) to 0.77×10^(11)CFU/kg for hybrid yellow catfish according to the quadratic regression method by plotting specific growth rate(SGR),feed conversion ratio(FCR),MDA and activities of AMS against dietary B.velezensis YFI-E109 levels.

Pathogenic infection and microbial composition of yellow catfish(Pelteobagrus fulvidraco)challenged by Aeromonas veronii and Proteus mirabilis

The catfishes are a group of economically important freshwater fish in China,which in recent years have suffered heavy losses as a result of bacterial outbreaks.In this study,we examined the diversity of the microbiome of infected skin mucus of yellow catfish(Pelteobagrus fulvidraco)and channel catfish(Ictalurus punctatus)and analyzed the bacterial pathogens.We found several common pathogenic bacteria,such as Aeromonas spp.,Vibrio spp.,Moraxella spp.and Proteus spp.present in both fish species,but with significantly different bacterial community structures.We isolated and cultured Aeromonas veronii and Proteus mirabilis and validated their infectivity in zebrafish(Danio rerio)and yellow catfish.Intraperitoneal injection of either bacteria into zebrafish,but not immersion,caused 100%mortality and ovary fragmentation.Yellow catfish was more sensitive than zebrafish with 100%mortality in the immersion challenges with A.veronii or P.mirabilis,and with a higher abundance of A.veronii in the P.mirabilis-challenged group compared to control.To our knowledge,this is the first study on the pathogenicity of P.mirabilis in yellow catfish,and the results will help to develop effective strategies for the disease prevention and control in catfish farming.

Effects of dietary arginine levels on growth performance,body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish(Pelteobagrus fulvidraco)

This experiment was conducted to investigate the effects of dietary arginine levels on growth performance, body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish(Pelteobagrus fulvidraco). Five isonitrogenous and isolipidic diets(42%protein and 9% lipid) were formulated to contain graded levels of arginine(2.44%, 2.64%, 2.81%, 3.01% and3.23% of diet), by supplementing L-Arginine HCI. Seven hundred juvenile yellow catfish with an initial average body weight of 1.13 ± 0.02 g were randomly divided into 5 groups with 4 replicates of 35 fish each and each group was fed one of the diets. After 56 d feeding, fish were exposed to 100 mg/L of ammonia-nitrogen for 72 h. The results showed that weight gain(WG) and specific growth rate(SGR) in2.64% and 2.81% groups were significantly higher than those in 3.23% group(P < 0.05). The feed conversation ratio(FCR) in 2,64%, 2,81% and 3.01% groups was significantly decreased when compared with3,23% group. The protein efficiency ratio(PER) in 2.64% group was significantly higher than that in 2.44%and 3.23% groups(P < 0.05). The condition factor(CF) of fish was significantly higher in 2.81% group than that in 2,44% group(P < 0.05). Dietary arginine levels had no significant effect on hepatosomatic index(HSI), viscerosomatic index(VSI), and whole-body dry matter, crude protein, crude lipid, ash contents, as well as serum total protein(TP), triglyceride(TG), glucose(GLU), urea nitrogen(UN) contents and aspartate aminotransferase(AST), alanine aminotransferase(ALT) activities(P> 0.05). After the fish were challenged to ammonia-nitrogen for 72 h, their cumulative mortality rate in 2.81% group was significantly lower than that in 2.44% group(P < 0.05). The results suggested that dietary arginine level at 2.81%could optimize anti-ammonia-nitrogen stress ability of juvenile yellow catfish and a level of 3.23%arginine seemed to depress the growth performance of fish and decreased their tolerance to the ammonia-nitrogen stress under current study. A quadratic regression analysis based on WG indicated that the optimal dietary arginine requirement of juvenile yellow catfish was estimated to be 2.74% of the diet(6.45% of dietary protein) under current culture conditions.

Mucosal immune responses and protective efficacy in yellow catfish after immersion vaccination with bivalent inactivated Aeromonas veronii and Edwardsiella ictaluri vaccine

Mucosal vaccination,which has the potential to induce both mucosal and systemic immune responses,is considered the most suitable method of preventing infectious diseases in farmed fish.Aeromonas veronii and Edwardsiella ictaluri are two pathogenic bacteria found in yellow catfish and often infect the fish through mucosal surfaces.Delivery of a bivalent inactivated vaccine by injection has been shown to induce a strong systemic immune response against both bacterial infections.However,mucosal immune responses and protective efficiency induced by this inactivated vaccine administrated via immersion are yet to be investigated.We developed a bivalent vaccine containing formalin-inactivated A.veronii and E.ictaluri and evaluated the immune response in yellow catfish after immersion vaccination using body fluids biochemistry indices,agglutinating antibody titers,and the expression level of immune-related genes in the skin,gills,spleen,and head kidney.The activities of innate immune-related enzymes and specific agglutination antibody titers in body fluids,as well as the expression of innate and adaptive immune-related genes in both the mucosal and systemic tissues of vaccinated fish,were significantly higher than that in control fish.Next,we assessed the protective efficacy by a challenge model of virulent strains of E.ictaluri and A.veronii.The relative survival percent of vaccinated fish was 80%and 87%after challenging fish with E.ictaluri and A.veronii,respectively,which was higher than unvaccinated control fish(43%and 57%).These results confirm that the bivalent inactivated vaccine administered via immersion induces a strong mucosal immune response and confers good protection against both E.ictaluri and A.veronii.Our results also reinforce the notion that immersion vaccination could stimulate both mucosal and systemic immunity contributing to protection against pathogens.

A novel PDZ domain-containing gene is essential for male sex differentiation and maintenance in yellow catfish(Pelteobagrus fulvidraco)

The sex-determining genes are found to be variable among different fish species. Yellow catfish(Pelteobagrus fulvidraco) is an important aquaculture fish species in China with XX/XY sex-determining type. Recently, YY super-male yellow catfish has been successfully produced by combining hormonalinduced sex reversal method with sex chromosome-linked markers. Here, we identified a novel PDZ domain-containing gene in yellow catfish designated as pfpdz1, in whose intron the sex-linked marker was located. The coding sequence of pfpdz1 in Y chromosome was identical to that in X chromosome except a missense SNP(A/T) that changes an amino acid(E8V) in the N-terminal region. Pfpdz1 displayed male-specific expression during sex differentiation. Overexpression of pfpdz1 using additive transgenesis induces XX ovary to differentiate into testis-like tissue, while the targeted inactivation of pfpdz1 in Y chromosome using CRISPR/Cas9-mediated mutagenesis triggers ovarian differentiation. Furthermore,we demonstrated that pfpdz1 initiates testicular differentiation through upregulating expression of amh, dmrt1 and sox9a1, as well as downregulating expression of cyp19a1, foxl2 and wnt4. Our data provide functional evidence that pfpdz1 is significant for male differentiation and maintenance in yellow catfish.

Cloning,expression pattern,and potential role of MAPKp38 and NF-κBp65 in response to lipopolysaccharide in yellow catfish(Pelteobagrus fulvidraco)

Mitogen-activated protein kinases(MAPK) and nuclear factor kappa B(NF-κB) pathways are considered to be two crucial intracellular signaling cascades in pro-inflammatory responses.In this study,we reported the coding sequences(CDS) of MAPKp38 and NF-κBp65 from yellow catfish.We also investigated the gene structure,expression patterns and functional role in yellow catfish.The CDS of MAPKp38 is1,086 bp encoding 361 amino acids(AA).The MAPKp38 protein has a long highly conserved serine/threonine protein kinases catalytic domain.The NF-κBp65 CDS is 1,794 bp,and the gene encodes 597 AA,with a Rel homology domain(RHD) which consists of a RHD-DNA-binding domain and an Ig-like,plexins,transcription factors(IPT) domain.Moreover,MAPKp38 and NF-κBp65 protein of bony fish and other vertebrates have a single clade.Quantitative real-time PCR analysis revealed the presence of the MAPKp38 and NF-κBp65 transcript in 12 tissues of healthy yellow catfish.The highest expression levels of MAPKp38 and NF-κBp65 were detected in the heart and liver,respectively.Upon stimulation with an intraperitoneal injection of lipopolysaccharide(LPS),the expression levels of MAPKp38 and NF-κBp65 were up-regulated in the intestine.These results indicated that MAPKp38 and NF-κBp65 play important roles in mediating the response protection against LPS in yellow catfish.

饵料中添加螺旋藻粉对黄颡鱼抗氧化能力、血清生化指标及体成分的影响

文章旨在探究饵料中添加螺旋藻粉对黄颡鱼抗氧化能力、血清生化指标及体成分的影响。试验将800尾黄颡鱼随机分为4组,每组5个重复,每个重复40尾,试验共计42 d。各组分别饲喂在基础日粮中添加0%、4%、8%、12%的螺旋藻粉的试验日粮。结果表明:8%和12%的螺旋藻粉组黄颡鱼血清总抗氧化能力(T-AOC)、谷胱甘肽过氧化物酶活性(GSH-Px)显著提高(P<0.05),丙二醛(MDA)含量显著降低(P<0.05);8%和12%的螺旋藻粉组黄颡鱼肌肉中T-AOC能力、GSH-Px活性显著提高(P<0.05);8%的螺旋藻粉组黄颡鱼肌肉中MDA含量显著降低(P<0.05);此外,螺旋藻粉对黄颡鱼血清过氧化氢酶(CAT)活性、还原型谷胱甘肽(GSH)含量无显著影响(P>0.05),螺旋藻粉对黄颡鱼肌肉中CAT活性、GSH含量无显著影响(P>0.05)。8%和12%螺旋藻粉组黄颡鱼血清总蛋白、尿素氮含量显著降低(P<0.05);此外,螺旋藻粉对黄颡鱼血清白蛋白、甘油三酯含量及谷丙转氨酶和谷草转氨酶活性无显著影响(P>0.05)。8%和12%的螺旋藻粉组黄颡鱼体粗蛋白质含量显著降低(P<0.05);8%和12%的螺旋藻粉组黄颡鱼体总风味氨基酸含量显著降低(P<0.05);4%~12%的螺旋藻粉组黄颡鱼体总必需氨基酸含量显著降低(P<0.05);8%和12%的螺旋藻粉组黄颡鱼体总非必需氨基酸含量显著降低(P<0.05);此外,螺旋藻粉对黄颡鱼体粗脂肪、水分及粗灰分含量无显著影响(P>0.05)。总之,尽管螺旋藻粉能有效提高黄颡鱼的抗氧化能力,但过量添加螺旋藻粉对其血清生化指标及体营养均有一定的负面影响。

黄颡鱼硒蛋白基因的克隆与分析

为探讨黄颡鱼硒蛋白selenow2a、selenop2和selenot2基因之间的关系,采用3′/5′RACE PCR克隆得到3个基因的cDNA全长,分别为891、1998和1432bp,其中ORF长度分别为288、828和600bp,编码95、275和219个氨基酸。在线工具SECISerach3对3个基因的cDNA序列分析结果显示,它们都含有可以编码硒代半胱氨酸的终止密码子,以及在3′非编码区存在SECIS元件。通过氨基酸序列比对和系统发育树分析,发现sele-now2a、selenop2和selenot2基因预测得到的氨基酸序列与斑马鱼(Danio rerio)氨基酸相似性分别为82.24%、66.19%和79.45%,而与斑点叉尾鮰(Ictalurus punetaus)的氨基酸相似性分别为94.74%、68.50%和90.95%,在发育树上则显示为树杈相接近。采用实时荧光定量PCR检测3个硒蛋白基因的mRNA在黄颡鱼心脏、肝脏、肌肉、脑、肠、脾脏、精巢和卵巢组织中的表达,结果显示其mRNA表达水平呈现组织特异性。表明3个基因拥有硒蛋白家族的特征,但在组织表达上具有特异性。

β-伴大豆球蛋白诱导杂交黄颡鱼肠道上皮细胞内质网应激模型的建立

实验旨在利用β-伴大豆球蛋白构建黄颡鱼上皮细胞内质网应激(Endoplasmic reticulum stress,ERS)模型。利用酶消化法分离得到黄颡鱼肠道上皮细胞,通过细胞形态、角蛋白18(Cytokeratin-18,CK-18)免疫荧光染色和碱性磷酸酶染色法鉴定。利用不同浓度β-伴大豆球蛋白刺激24h后,RT-qPCR检测相关基因转录表达水平,筛选最合适刺激浓度。在此浓度下分别刺激黄颡鱼肠道上皮细胞0、12h、24h和36h,使用RTqPCR、CCK8、透射电镜和免疫荧光染色等方法检测相关指标,筛选最适刺激时间。结果表明:(1)成功分离培养黄颡鱼肠道上皮细胞,细胞呈铺路石状,CK-18和碱性磷酸酶染色呈阳性;(2)成功筛选到4 mg/mLβ-伴大豆球蛋白为最佳刺激浓度。在该浓度下,除grp78、jnk、il-10、atf6外,内质网应激、自噬、凋亡、炎症等相关基因表达水平均显著最高(P<0.05);成功筛选24h为最适刺激时间。4 mg/mL β-伴大豆球蛋白刺激细胞24h显著降低细胞活力,同时引起内质网显著肿胀,GRP78、LC3、Caspase3蛋白表达和Tunel信号显著升高(P<0.01),perk、atf6、beclin1、lc3a、bcl2、caspase3、caspase9和il-12 mRNA表达水平显著最高(P<0.05)。综上,实验成功分离得到黄颡鱼肠道上皮细胞,构建了黄颡鱼肠道上皮细胞内质网应激模型。实验为进一步研究未折叠反应信号通路在黄颡鱼豆粕诱导肠炎发生发展中的作用奠定基础。

酵母培养物替代鱼粉对黄颡鱼生长性能、血清生化、体成分、抗氧化及免疫力的影响

为研究酵母培养物替代鱼粉对黄颡鱼生长性能、血清生化、体成分、抗氧化及免疫能力的影响,选用初始体重为(25.00±0.15)g的黄颡鱼600尾,随机分为2组,每组3个重复,每个重复100尾鱼,以基础饲料为对照组(CK),添加酵母培养物1∶1替代基础饲料中鱼粉为试验组(LYF),饲养42?d后采样分析。结果显示:与对照组相比,酵母培养物能提高黄颡鱼的相对诱食率10.43%(P <0.05),提高增重率和特定生长率,降低饲料系数,对黄颡鱼生长有一定的促进作用。酵母培养物对黄颡鱼全鱼体成分无显著影响(P> 0.05);能显著降低黄颡鱼血清谷草转氨酶(AST)活性(P <0.05),降低25.73%;显著降低黄颡鱼血清丙二醛(MDA)含量(P <0.05),降低71.80%;试验组黄颡鱼血清溶菌酶(LZM)和碱性磷酸酶(AKP)活性显著增加(P <0.05),分别提高61.22%和65.63%。由此得出,酵母培养物1∶1替代鱼粉不会影响黄颡鱼的生长性能、肝脏健康、体成分,还能提高黄颡鱼的抗氧化能力和免疫力。

EM菌对杂交黄颡鱼“黄优1号”越冬期间养殖池水质、生长特性及非特异性免疫指标的影响

为探究EM菌对越冬期间杂交黄颡鱼“黄优1号”养殖池水质、生长性能及非特异性免疫指标的影响,分别采用泼洒、拌料两种方式,使用EM菌饲养杂交黄颡鱼“黄优1号”[体质量(10.35±1.23)g,体长(8.5±0.4)cm],进行了42 d的饲养对比试验。结果显示:养殖期间采用泼洒方式使用EM菌,该组养殖水体的溶解氧含量高于拌料使用EM菌组和对照组,氨氮和亚硝酸盐含量始终低于拌料使用EM菌组和对照组;拌料使用EM菌组杂交黄颡鱼“黄优1号”的存活率、增重率和特定生长率要高于另外两组,且脏体指数和肝体指数低于另外两组;两个使用EM菌试验组的酸性磷酸酶活性、碱性磷酸酶活性、超氧化物歧化酶活性和溶菌酶活性均显著高于对照组(P<0.05),且拌料组尤为显著。试验结果表明,使用EM菌能在一定程度上改善越冬期间养殖池的水质,对杂交黄颡鱼“黄优1号”生长具有明显的促进作用,并可增强其越冬后的非特异性免疫功能。

饲料中添加还原型谷胱甘肽对黄颡鱼幼鱼生长性能、血清生化、抗氧化和免疫指标的影响

本试验旨在研究在饲料中添加还原型谷胱甘肽对黄颡鱼幼鱼生长、血清生化、抗氧化能力和免疫力的影响。选用初始体重为(11.00±0.15)g的黄颡鱼1800尾,随机分为2组,每组3个重复,每个重复300尾鱼,不添加任何谷胱甘肽的基础饲料为空白对照组(CK),试验组向基础饲料中添加350 mg/kg还原型谷胱甘肽(GSH),饲养42 d后采样分析。结果显示:与对照组相比,GSH组黄颡鱼终末体质量、增重率和特定生长率显著增加(P <0.05),饲料系数显著降低(P <0.05);GSH组黄颡鱼的血清谷草转氨酶(AST)、血清白蛋白(ALB)、高密度脂蛋白胆固醇(HDL-C)含量相比于对照组显著增加(P <0.05);GSH组黄颡鱼血清GSH含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、溶菌酶(LZM)和碱性磷酸酶(AKP)活性相比于对照组显著提高(P <0.05)。由此得出,在饲料中添加350 mg/kg还原型谷胱甘肽可提高黄颡鱼的生长性能,增强机体抗氧化能力和免疫力。

酸化剂对黄颡鱼生长、抗氧化能力和非特异性免疫的影响

本试验旨在研究饲料添加酸化剂对黄颡鱼(Pelteobagrus fulvidraco)的生长、抗氧化能力和非特异性免疫的影响。对照组饲料不含酸化剂,试验组在对照组饲料基础上分别添加0.05%(0.05%组)、0.10%(0.10%组)、0.20%(0.20%组)和0.50%(0.50%组)的酸化剂,共配制5种等氮等脂饲料。选用初始体重为(7.27±0.38)g的黄颡鱼675尾,随机分为5组,每组3个重复,每个重复45尾鱼,养殖试验进行64 d。结果表明:黄颡鱼的终末体重、增重率、特定生长率和肥满度在0.10%组达到最高值,0.50%组的肝体比显著高于其他组(P<0.05)。与对照组相比,黄颡鱼全鱼粗脂肪和粗灰分含量均在0.10%组达到最高值,肠道脂肪酶和胰蛋白酶活性在0.10%组达到最高值。饲料添加酸化剂后,黄颡鱼肝脏总抗氧化能力和过氧化氢酶活性均较对照组有显著的提高(P<0.05)。随着饲料中酸化剂添加水平的升高,酸化剂添加组肠道丙二醛含量显著降低(P<0.05)。0.10%组的肠道超氧化物歧化酶活性和0.20%组的黄颡鱼血清碱性磷酸酶活性显著高于其他组(P<0.05)。0.10%组的黄颡鱼血清高密度脂蛋白胆固醇含量显著高于对照组(P<0.05),血清总胆固醇、甘油三酯和高密度脂蛋白胆固醇含量在0.10%组达到最高值。综上所述,在饲料中添加0.10%的酸化剂可提高黄颡鱼的生长性能和消化能力,增强其抗氧化能力和免疫力。

酶解鱿鱼内脏浆超滤分离物对黄颡鱼生长性能和生理健康的影响

为探讨酶解鱿鱼内脏浆滤过液(HSVP-A)和酶解鱿鱼内脏浆截留物(HSVP-B)对黄颡鱼生长的影响,试验以初始体重为(14.21±0.09)g的黄颡鱼幼鱼为试验对象,以30%、15%和0秘鲁超级蒸汽鱼粉(FM、HFM和NFM组)为对照,在15%鱼粉日粮和无鱼粉日粮中按0.5%、1.5%、2.5%和3.5%的梯度添加HSVP-A和HSVP-B,共设计19组等氮等脂日粮,每组3个重复,每个重复40尾,养殖8周后采样。结果表明:(1)与NFM组相比,NB-4组的成活率显著降低(P<0.05),其他试验组成活率与对照组相比无显著差异(P>0.05);(2)与FM组相比,HA-2和NB-4组的特定生长率(SGR)升高,差异不显著(P>0.05);(3)以NFM组为对照,NB-4组的谷丙转氨酸(AST)和谷草转氨酸(ALT)含量显著降低(P<0.05),NB-4组的低密度脂蛋白(LDL)含量显著增加(P<0.05);(4)HA-2组以HFM组为对照,NB-4组以NFM组为对照,两个试验组的总抗氧化能力(T-AOC)升高,丙二醛(MDA)含量降低,差异显著(P<0.05),并且HA-2组的超氧化物歧化酶(SOD)活性显著升高(P<0.05)。研究表明在日粮动物蛋白总量相同的基础上,15%鱼粉日粮中添加1.5%HSVP-A以及无鱼粉日粮中添加3.5%HSVP-B对黄颡鱼的生长性能最好,与30%鱼粉组表现出一定的等效关系。

环境浓度氧四环素与聚苯乙烯微塑料对黄颡鱼幼鱼肠道的联合毒性效应

近年来,氧四环素(oxytetracycline,OTC)和聚苯乙烯微塑料(polystyrene microplastics,PS-MPs)在水环境中被广泛检出。为了探究PS-MPs与OTC对鱼类的联合毒性效应,选取黄颡鱼(Pelteobagrus fulvidraco)幼鱼为研究对象,将其暴露于CON(对照)组、环境浓度OTC(500 ng·L^(-1))单独组、MPs-L(100μg·L^(-1)PS-MPs)单独组、MPs-L+OTC(100μg·L^(-1)PS-MPs+500 ng·L^(-1)OTC)复合组、MPs-H(1000μg·L^(-1)PS-MPs)单独组和MPs-H+OTC(1000μg·L^(-1)PS-MPs+500 ng·L^(-1)OTC)复合组中28 d,研究了OTC和PS-MPs单独以及联合暴露对幼鱼生长、肠道结构和肠道菌群的影响。研究结果表明,与对照组相比,OTC单独暴露和MPs-L单独暴露对黄颡鱼幼鱼体长、体质量及体质量增长率,肠道氧化应激酶(超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT))活性及消化酶(胰蛋白酶(trypsin,TRS)、淀粉酶(amylase,AMS)和脂肪酶(lipase,LPS))活性,肠道微生物组成(OTU数目、α多样性、β多样性以及门、属水平上物种组成的相对丰度)均无显著性影响。但MPs-L+OTC复合暴露导致SOD和CAT活性显著升高,引起肠道空泡化、肠上皮细胞轻微缺失,变形菌门的相对丰度显著升高,且与OTC单独暴露组相比,肠道CAT活性显著性升高。MPs-H单独暴露抑制了黄颡鱼幼鱼体质量和体质量增长率,引起了肠道空泡化,导致其肠道SOD和CAT活性显著升高,消化酶TRS和LPS活性显著降低,厚壁菌门相对丰度显著降低。与MPs-H单独组和OTC单独组相比,MPs-H+OTC组进一步加剧肠道氧化酶活性升高、消化酶活性降低、肠道损伤和肠道菌群紊乱。相关性分析表明,肠道葡萄球菌属和体长显著负相关;鲸杆菌属和SOD显著正相关;气单胞菌属与LPS显著负相关,与AMS显著正相关。上述结果显示PS-MPs高浓度单独以及与OTC复合暴露可能通过肠道损伤以及肠道菌群的改变,进而影响肠道消化酶活性,导致黄颡鱼幼鱼生长抑制。此外,PS-MPs和OTC的复合肠道毒性表现出显著的协同效应。本实验结果将为水环境中抗生素和微塑料的生态风险评价提供新的视角和理论依据。

饲料中小球藻添加量对杂交黄颡鱼“黄优1号”生长性能的影响

开展了饲料中小球藻添加量对杂交黄颡鱼“黄优1号”生长性能和抗氧化能力影响试验。共设置5组,分别为1个对照组(G0)和4个处理组(G1—G4)。其小球藻的添加量分别为0.00%(G0),2.50%(G1),5.00%(G2),7.50%(G3)和10.00%(G4)。于养殖的第28和56天,测定杂交黄颡鱼“黄优1号”鱼体生长指标和抗氧化能力指标。结果表明,随着饲料中小球藻含量的增加,杂交黄颡鱼“黄优1号”的体质量增加率和特定体质量增加率呈上升趋势,并显著高于对照组(P<0.05),饵料系数呈下降趋势,肝体指数较对照组无显著差异(P>0.05)。抗氧化能力方面,饲料中添加小球藻可以显著提高杂交黄颡鱼“黄优1号”肝脏和血清中超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶的活性,能降低鱼体内丙二醛含量。指出,饲料中添加小球藻不仅可以促进杂交黄颡鱼“黄优1号”的生长,并提高其抗氧化能力。

饲料添加三丁酸甘油酯对黄颡鱼幼鱼生长性能、血清生化指标、免疫功能和抗氧化能力的影响

本试验旨在研究饲料中添加三丁酸甘油酯对黄颡鱼(Pelteobagrus fulvidraco)幼鱼生长性能、血清生化指标、免疫功能和抗氧化能力的影响。以480尾初始体重为(5.53±0.02)g的黄颡鱼幼鱼为研究对象,随机分为4组,分别投喂添加0(G0)、500(G1)、1000(G2)、2000 mg/kg(G3)三丁酸甘油酯的4种等氮等脂的试验饲料,每组3个重复,每个重复40尾。试验期为56 d。结果显示:1)G2组增重率和饲料效率显著高于其他各组(P<0.05)。G1组肥满度显著低于G0和G3组(P<0.05),与G2组无显著差异(P>0.05)。2)G3组血清葡萄糖含量显著高于G1和G2组(P<0.05),各组间的血清总蛋白、白蛋白、球蛋白、甘油三酯、尿素氮含量及谷丙转氨酶、谷草转氨酶活性无显著差异(P>0.05)。3)与G0组相比,G1、G2和G3组的血清溶菌酶活性显著升高(P<0.05),G1和G2组血清碱性磷酸酶活性显著升高(P<0.05),G2组的血清免疫球蛋白M含量显著高于G3组(P<0.05),各组间的血清补体3含量无显著差异(P>0.05)。4)与G0组相比,G1组血清总抗氧化能力显著升高(P<0.05),G1、G2和G3组的血清超氧化物歧化酶活性显著升高(P<0.05)。G3组血清过氧化氢酶活性显著高于G0、G1和G2组(P<0.05),各组间的血清谷胱甘肽过氧化物酶活性及谷胱甘肽和丙二醛含量无显著差异(P>0.05)。综上所述,饲料中添加500~2000 mg/kg三丁酸甘油酯能够显著提高黄颡鱼非特异性免疫和抗氧化能力,其中添加1000 mg/kg三丁酸甘油酯显著提高了黄颡鱼增重率和饲料效率。结合生长性能及血清免疫功能、抗氧化能力指标综合评价,黄颡鱼饲料中三丁酸甘油酯的最适添加水平为1000 mg/kg。

饲料中添加马尾藻多糖对杂交黄颡鱼生长性能、血清生化指标、消化酶活性和抗氧化能力的影响

为研究饲料中添加马尾藻多糖对杂交黄颡鱼(黄颡鱼♀×瓦氏黄颡鱼?)生长性能、血清生化指标、消化酶活性和抗氧化能力的影响,以(5.02±0.05)g杂交黄颡鱼为研究对象,在饲料中分别添加0(对照组)、0.10%、0.20%、0.40%、0.60%和0.80%的马尾藻多糖,喂养杂交黄颡鱼60 d后测定增重率、特定生长率等生长性能指标以及血清生化指标、抗氧化指标和胃、肠道消化酶活性。结果显示:1)饲料中马尾藻多糖的添加量为0.40%~0.60%时,与对照组相比,杂交黄颡鱼的增重率和特定生长率显著增加(P<0.05),饲料系数显著降低(P<0.05);2)杂交黄颡鱼血清总蛋白含量各组之间差异不显著(P>0.05),但以0.60%马尾藻多糖组最高,且在马尾藻多糖添加量为0.60%及以上时,血清谷草转氨酶、谷丙转氨酶和碱性磷酸酶活性较对照组显著降低(P<0.05);3)饲料中马尾藻多糖的添加量为0.40%~0.80%时,杂交黄颡鱼胃和肠道中蛋白酶、淀粉酶和脂肪酶活性较对照组显著提高(P<0.05),且肠道中蛋白酶、淀粉酶和脂肪酶活性在0.60%马尾藻多糖组最高;4)与对照组相比,饲料中马尾藻多糖的添加量为0.40%~0.80%时杂交黄颡鱼血清超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶活性显著升高(P<0.05),血清丙二醛含量显著降低(P<0.05),其中血清超氧化物歧化酶和谷胱甘肽过氧化物酶活性均以0.60%马尾藻多糖组最高。综合生长性能、血清生化指标、抗氧化酶活性和消化酶活性,建议杂交黄颡鱼[(5.02±0.05)g]饲料中马尾藻多糖的添加量为0.60%。