迟缓爱德华氏菌间接ELISA快速检测法

以迟缓爱德华氏菌(Edwardsiella tarda)WY28作为抗原,免疫新西兰兔,获得效价为1:2 048的多克隆抗体;以此多克隆抗体作为-抗,山羊抗兔IgG-HRP作为酶标二抗,建立迟缓爱德华氏菌的间接EIJSA快速检测法.采用棋盘滴定法确定抗原与一抗的最佳工作浓度分别为106 CFU·mL-1和1:10 000;酶标二抗的最适工作浓度为1:1 000.病原菌检测灵敏度为每孔103 CFU.该方法标准化后具有快速、灵敏等特性,与肠杆菌科其他细菌参考菌株无交叉反应,具良好的特异性.对养殖场发病大菱鲆(Scophthalmus maximus)和半滑舌鳎中分离的细菌菌株进行检测,从56株分离菌株中检测出27株迟缓爱德华氏菌,阳性检出率为48.2%.该方法的建立有助于快速准确地诊断由迟缓爱德华氏菌引起的养殖鱼类病害.     

施氏鲟病原嗜水气单胞菌ELISA快速检测方法的研究

以施氏鲟(Acipenser schrenchii)细菌性败血症病原菌嗜水气单胞菌为抗原,免疫兔获得高免血清,建立一种快速检测施氏鲟细菌性败血症病原菌嗜水气单胞菌的ELISA技术。结果显示:采用棋盘滴定法确定抗原和抗血清的最适工作浓度分别为107CFU/mL和1∶20000;病原菌检测灵敏度为每孔104CFU;抗血清与其它细菌标准菌株的交叉反应结果均呈阴性;阻断实验中的阻断率达66.88%;交叉反应和阻断实验的结果表明该方法具有较高的特异性。将该方法标准化后检测了22份人工感染后的施氏鲟和健康施氏鲟,阳性检测率分别为90.9%和13.6%,表明该技术不仅能够检测已发病的施氏鲟,而且能够检测带菌的施氏鲟。     

施氏鲟肿嘴病快速检测方法的研究

以施氏鲟(Acipenser schrenckii)肿嘴病病原菌异常嗜糖气单胞菌(A.allosaccharophila)为抗原,免疫兔获得高免血清,建立一种快速检测施氏鲟肿嘴病病原菌的ELISA技术。结果显示:采用棋盘滴定法确定抗原和抗血清的最适工作浓度分别是为107CFU和1∶100000;病原菌检测灵敏度为每孔104CFU;抗血清与其它细菌标准菌株的交叉反应均呈阴性;阻断试验中的阻断率达67.3%;交叉反应和阻断试验的结果表明该方法具有较高的特异性。将此方法标准化后,对35份人工感染后的施氏鲟和健康施氏鲟进行检测,阳性的检出率分别为88.6%和14.3%,表明该技术不但可以检测已经发病的施氏鲟,而且还可以检测带菌的施氏鲟。     

凡纳滨对虾红体病病原菌间接ELISA快速检测方法的研究

以凡纳滨对虾红体病病原菌副溶血弧菌为抗原,免疫兔获得高免血清,建立一种快速检测凡纳滨对虾红体病病原菌副溶血弧菌的ELISA技术。采用棋盘滴定法确定抗原和抗血清的最适工作浓度分别为106CFU·mL-1和1∶2000;病原菌检测灵敏度为每孔104CFU;抗血清与其它细菌标准菌株的交叉反应结果均呈阴性;阻断实验中的阻断率达75.88%;交叉反应和阻断实验结果表明该方法具有较高的特异性。将该方法标准化后检测了30份人工感染后的凡纳滨对虾和健康凡纳滨对虾,阳性检测率分别为93.3%和13.3%,表明该技术不仅能够检测已发病的凡纳滨对虾,而且能够检测带菌的凡纳滨对虾,这对于水产养殖业中疾病的早期诊断有着重要意义。     

罗非鱼无乳链球菌巢式PCR检测方法的建立

根据无乳链球菌(Streptococcus agalactiae)cfb基因序列,设计、合成2对引物,优化扩增条件,建立了快速高灵敏度鉴别无乳链球菌的巢式PCR方法。结果显示:使用该方法对罗非鱼(Oreochromis mossambicus)血液样品进行检测,可检测到活菌浓度为8.7×104CFU/m L的无乳链球菌。对采自广西地区受无乳链球菌感染的19份罗非鱼样品进行检测,18份可获得目的片段,扩增到的序列均为无乳链球菌cfb基因序列,检测准确度达到94.7%。     

罗非鱼源无乳链球菌兼职蛋白EF-Tu的克隆、表达及其抗原性检测

为检测罗非鱼源无乳链球菌兼职蛋白EF-Tu(延伸因子Tu,Elongation Factor Tu)的抗原性,本实验克隆了罗非鱼源无乳链球菌HN0303的EF-Tu基因序列,并进行了蛋白相关性质的预测和系统发育树的构建。通过原核表达得到EF-Tu重组蛋白,同时利用纯化的蛋白免疫家兔获得多克隆兔抗EF-Tu重组蛋白血清以用于EF-Tu蛋白抗原性检测。结果显示,罗非鱼源无乳链球菌HN0303 EF-Tu基因有1个由1197个碱基组成的ORF,编码398个氨基酸。生物信息学分析显示其分子式为C_(1933)H_(3096)N_(532)O_(615)S_(11),分子质量为43.981 ku,理论等电点为4.749;具有多个磷酸化位点,不具有信号肽和跨膜区域;具有保守的EFTu结构域、EF-Tu-II结构域和EF-Tu-Ⅲ结构域,且与其他来源无乳链球菌的EF-Tu蛋白具有很高的同源性;具有较高的抗原指数,表明其可形成多个抗原表位。SDS-PAGE检测发现,诱导表达的重组蛋白以包涵体的形式出现在沉淀中,大小约为66.4 ku。Western Blot分析表明,兔抗EF-Tu重组蛋白血清能分别特异性结合菌体蛋白和EF-Tu重组蛋白。同时使用兔抗EF-Tu重组蛋白血清封闭罗非鱼源无乳链球菌HN0303表面的EF-Tu蛋白后,无乳链球菌HN0303粘附EPC(Epithelioma papulosum cyprini,鲤鱼上皮细胞)的能力下降了79.99%±2.43%。本研究表明,原核表达的罗非鱼源无乳链球菌EF-Tu重组蛋白具备较好的抗原性,用其制备的兔抗血清能够较好地抑制罗非鱼源无乳链球菌的粘附,推测其可能为罗非鱼源无乳链球菌亚单位疫苗的候选蛋白。     

基于毒力基因的罗非鱼无乳链球菌三重PCR检测方法的建立及应用

无乳链球菌(Streptococcus agalactiae)作为罗非鱼主要病原,传染力强、致死率高,部分鱼从发病到死亡无明显病症,难以确定鱼体是否携带该病原菌,建立适用于生产一线的无乳链球菌检测技术势在必行。根据GenBank中无乳链球菌透明质酸酶基因(hylB)、青霉素结合蛋白基因(pon A)和CAMP因子基因(cfb)的保守序列,设计3对特异性引物,对多重PCR的反应条件和体系进行优化,建立基于毒力基因的罗非鱼无乳链球菌三重PCR检测方法,并运用该方法检测来自广东省不同地区的罗非鱼组织样品。构建的三重PCR检测方法仅在无乳链球菌中扩增出3条特异性条带,而在罗非鱼和常见的水产病原菌菌株中均未扩增出任何条带,表现出良好的特异性;以无乳链球菌基因组DNA浓度7.24×10~(–5)~5.65 ng/μl为模板进行扩增,该三重PCR能检测到的最低模板浓度为1.81×10~(–3) ng/μl,表现出较高的灵敏度;运用该方法检测188个罗非鱼组织样品,其阳性检出率与常规细菌分离鉴定阳性率一致,以常规细菌分离鉴定为标准,对该三重PCR检测方法进行评价,其诊断敏感性(Dse)和诊断特异性(Dsp)均为100%。结果表明,构建的三重PCR检测方法不仅显著提高了检测的准确度和灵敏度,还可在同一反应中同时检测3种无乳链球菌毒力基因,为无公害水产品中无乳链球菌的快速检疫、水产养殖病害早期预警提供了一种快速、精准和高效的检测技术。     

BALB/c小鼠用于评价尼罗罗非鱼无乳链球菌毒力的研究

实验采用BALB/c小鼠作为实验动物,旨在建立尼罗罗非鱼无乳链球菌毒力测定的BALB/c小鼠模型。BALB/c小鼠经腹腔注射尼罗罗非鱼源无乳链球菌建立感染模型,比较了尼罗罗非鱼源无乳链球菌分别感染尼罗罗非鱼和小鼠的LD_(50)差异,分别测定了不同毒力尼罗罗非鱼无乳链球菌对尼罗罗非鱼和小鼠的毒力。结果显示,小鼠经腹腔注射无乳链球菌,在24 h内出现死亡现象,且对小鼠脑、肝脏、脾脏、肾脏等组织造成损伤。3次测定尼罗罗非鱼无乳链球菌TFJ0901对尼罗罗非鱼和小鼠LD_(50)分别为7.7×10~7、2.2×10~8、3.5×10~9 CFU/mL和405、361、419 CFU/只。将无乳链球菌TFJ0901和THN0901感染尼罗罗非鱼(1.0×10~7 CFU/mL)和小鼠(100 CFU/只),尼罗罗非鱼和小鼠存活率分别为100%、6.7%±5.8%和100%、0,其存活率都具有显著性差异。将无乳链球菌TFJ0901和TFJ-F感染尼罗罗非鱼(3.0×10~8 CFU/mL)和小鼠(2 500 CFU/只),尼罗罗非鱼的存活率分别为73.3%±11.5%和80.0%±10.0%,存活率差异不显著,小鼠存活率分别为13.3%±11.5%和100.0%,存活率具有显著性差异。研究表明,本实验成功建立了BALB/c小鼠作为尼罗罗非鱼源无乳链球菌毒力测定的稳定模型,测定不同毒力的尼罗罗非鱼源无乳链球菌对小鼠毒力与对尼罗罗非鱼毒力一致,且该模型能够区分尼罗罗非鱼模型难以区分的毒力相近的无乳链球菌。     

尼罗罗非鱼无乳链球菌Sip蛋白乳酸菌活载体口服疫苗的研制及其免疫效果

链球菌病是威胁我国罗非鱼养殖产业健康发展的重要病害之一。为研制出免疫效果好、操作简便的罗非鱼链球菌病疫苗,本研究构建重组表达无乳链球菌Sip蛋白的穿梭质粒pNZ8124-Sip,通过酶切和测序验证后电转化乳酸乳球菌NZ9000,获得能够诱导重组表达无乳链球菌Sip蛋白的乳酸菌活菌载体疫苗。采用SPS-PAGE电泳摸索最佳诱导浓度和诱导时间以获得最大表达量,通过镍柱纯化目的蛋白并进行Western blot检测;利用不同浓度的重组乳酸菌活载体疫苗灌胃口服免疫尼罗罗非鱼,采用间接ELISA法测定免疫后血清抗体水平变化,通过人工腹腔注射感染无乳链球菌获得相对免疫保护率。研究结果显示,构建的重组乳酸乳球菌可通过nisin诱导表达大小为48 ku特异性蛋白,与目的蛋白大小一致;PAGE电泳显示,重组蛋白主要以可溶蛋白和包涵体2种形式存在,其中胞内可溶性蛋白浓度达7.65 mg/mL;诱导表达的最佳条件为100 ng/mL nisin诱导6 h;Western blot检测结果显示,诱导蛋白可与鼠抗His标签抗体特异性结合。口服免疫结果显示,中浓度组(2.24×10~(10) CFU/mL)和低浓度组(2.24×10~9 CFU/mL)免疫2次能够显著提高尼罗罗非鱼的血清抗体水平和抗无乳链球菌感染能力,中浓度免疫组的相对免疫保护率最高为41.0%。本研究可为罗非鱼链球菌病口服疫苗的研究奠定基础,具有广阔的应用前景。     

尼罗罗非鱼无乳链球菌微滴式数字PCR检测方法的建立及临床应用

通过设计筛选引物和探针、优化反应浓度和退火温度,构建一种尼罗罗非鱼(Oreochromis niloticus)无乳链球菌(Streptococcus agalactiae)的微滴式数字PCR(dd PCR)检测方法,分析该方法的敏感性、特异性及重复性,并应用于临床样品检测。结果显示：当引物、探针浓度分别为0.9μmol·L^-1、0.3μmol·L^-1且退火温度为56.9℃时,建立的罗非鱼无乳链球菌dd PCR方法阴、阳性微滴分布界限明显,平均拷贝数高,有较高扩增反应效率;线性关系线良好(R²=0.997 3),最低检测限为2.56 copies·μL^-1;与猪链球菌2型、鱼类海豚链球菌和其他5种常见的水生动物疫病病原体无交叉反应;重复变异系数为3.15%;临床样品检测结果与实时荧光PCR方法结果的符合率100%,与细菌分离鉴定方法结果符合率为94.12%。结果表明,建立的罗非鱼无乳链球菌dd PCR检测方法灵敏度高、特异性强、重复性好,可对罗非鱼无乳链球菌感染的临床样品进行定量检测,为尼罗罗非鱼无...     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.