Tissue localization of Aeromonas salmonicida in Atlantic salmon, Salmo salar L., following experimental challenge

Three groups of Atlantic salmon, Salmo salar L., were exposed to live, colony-forming, radiolabelled Aeromonas salmonicida bacteria in a bath challenge: (1) fish with artificial wounds; (2) fish with a reduced epidermal mucus layer caused by removal of the mucus layer on two occasions by a swabbing procedure; and (3) a control group of untreated fish. Fish were killed 2, 6 and 24 h after challenge, and radioactivity (cpm g^–1) was measured in the blood, mucus, skin, wound area, gills, anterior kidney, posterior kidney, spleen, midgut and hindgut. The highest levels of radioactivity were measured in the wound areas and in the gills. There was a significant positive correlation between the levels of radioactivity in the gills and blood, and between the mucus and skin at 2 h post-challenge. Two hours after the bath challenge, live A. salmonicida bacteria were found in the blood of fish in the 'swabbed' and 'artificial wound' groups, and not in the control group. Twenty-four hours after the bath challenge, the kidney of fish from all groups contained viable bacteria, whereas the blood was negative.     

Structure and function of antimicrobial peptide penaeidin-5 from the black tiger shrimp Penaeus monodon

The gene for penaeidin-5, an antimicrobial peptide comprising 55 amino acids, was isolated from the hemocyte of black tiger shrimp (Penaeus monodon). RT-PCR expression tests revealed that penaeidin-5 was produced in hemocytes, gills, the intestine and muscle. Western blot analysis confirmed the panaeidin-5 was aboundantin hemocytes, the intestine and hemolymph. Immunohistochemistry revealedpenaeidin-5 in the cuticle and gills that are considered primary defense barriers. The deduced amino acid sequence of penaeidin-5 included a proline-rich N-terminal domain and a carboxyl-domain that contained six cysteine residues. Circular dichrosim analysis revealed an -helix in its secondary structure and the predicted 3D structure indicated two-disulfide bridges in the -helix. Based on the sequence of penaeidin-5 peptide cDNA, synthetic penaeidin-5 was prepared to carry out functional tests. The synthetic peptide had efficient bacteriostatic and bactericidal activity against Aerococcus viridans, and also inhibited the growth of two filamentous fungi, Fusarium pisi and Fusarium oxysporum. To measure penaeidin-5 in vivo, black tiger shrimp were challenged with Vibrio alginolyticus and A. viridans. At 3 h post-challenge, penaeidin-5 was induced and bacterial numbers decreased significantly by 12 h and 24 h.     

拟态弧菌感染黄颡鱼的动态病理损伤及病原分布研究

以1.0×106CFU·m L~(-1)拟态弧菌(Vibrio mimicus)浸浴感染黄颡鱼(Pelteobagrus fulvidraco),于第0、第4、第8、第16、第24、第36、第48、第60、第72小时剖杀取样,研究病理损伤及病原菌的体内动态分布。结果显示,皮肤肌肉、鳃、肠道出现病变最早,其中皮肤肌肉损伤最严重。第16小时表皮变性、坏死,鳃上皮肿胀,肠绒毛水肿;第24~第48小时表皮坏死、脱落,真皮严重出血,肌纤维变性、坏死,鳃出血,上皮局部坏死,肠上皮变性与灶性坏死;第48~第72小时皮肤肌肉坏死更严重,形成溃疡灶,鳃灶性坏死。肾、肝、脾与心36 h后相继出现不同程度的淤血、出血,变性和灶性坏死。q PCR检测发现,第4小时即在鳃、肠、皮肤肌肉检出病菌,细菌含量分别为1.3×102CFU·mg~(-1)、2.6×102CFU·mg~(-1)、4.7×102CFU·mg~(-1);鳃与皮肤肌肉中菌量随时间延长而增加,第72小时皮肤肌肉中菌量达到4.5×107CFU·mg~(-1);第24小时后相继在肾、肝、脾、心检出病菌,菌量介于1.9×10~4.7×102CFU·mg~(-1)之间。结果表明皮肤、鳃和肠道是病菌的入侵位点,并在体内多组织、器官分布。     

Furunculosis in Atlantic salmon (Salmo salar L.) is not readily controllable by bacteriophage therapy

The potential of bacteriophage therapy to control bacterial disease in farmed fish was tested using, as an example, furunculosis of Atlantic salmon, caused by Aeromonas salmonicida subsp. salmonicida.

In vivo testing with Atlantic salmon and rainbow trout (Oncorhynchus mykiss Walbaum) showed no adverse effects, with bacteriophage generally cleared within 96 h of administration by either intraperitoneal (i.p.) injection or oral in-feed.

Juvenile Atlantic salmon were administered a combination of bacteriophage O, R and B (1.9 × 10⁸ pfu fish^− 1) by i.p. injection, after they had been challenged with A. salmonicida subsp. salmonicida 78027, also by i.p. injection. The fish that were injected with bacteriophage immediately after challenge died at a significantly slower rate then those that were either not treated with bacteriophage, or treated 24 h post-challenge. However, the end result (100% mortality) was not affected.

In further experiments the effects of oral (1.88 × 10⁵ pfu g^− 1 fish^− 1 daily for 30 days), bath (1.04 × 10⁵ ml^− 1 daily for 30 days) and i.p. (6.25 × 10⁷ pfu fish^− 1) phage treatment to control furunculosis in experimentally infected Atlantic salmon were compared with antibiotherapy (treatment with 10 mg kg^− 1 bw^− 1 day^− 1 oxolinic acid for 10 days), using an indirect cohabitation challenge. No protection was offered by any of the bacteriophage treatments, compared to the positive challenge group, although significant protection was offered by the oxolinic acid treatment. Analysis of samples taken from the trials demonstrated that bacteriophage were correctly administered to the fish and, on occasion, were isolated from fish that had succumbed to furunculosis. It was also shown that bacteriophage resistant A. salmonicida subsp. salmonicida isolates could be recovered from mortalities in all the treatment groups.

The results suggest that, although there were no safety problems associated with the approach, furunculosis in Atlantic salmon is not readily controllable by application of bacteriophage.     

Streptococcus iniae infection and tissue distribution in hybrid striped bass (Morone chrysops×Morone saxatilis) following inoculation of the gills

This study was designed to test the possibility that Streptococcus iniae enters through the gills and causes infection in hybrid striped bass. To determine the dose response, four groups of fish were inoculated with S. iniae via the gills with a dose of 5.0×10⁵, 2.6×10⁶, 5.0×10⁶, or 1.0×10⁸ CFU/fish. One group of fish was inoculated with tryptic soy broth (TSB) via the gills to serve as controls. The cumulative percent mortality was 13%, 27%, 100% and 100% for 5.0×10⁵, 2.6×10⁶, 5.0×10⁶ and 1.0×10⁸ CFU/fish, respectively. We also examined the tissue dissemination of S. iniae at 0.5, 4, 8, 12, 24, 48 and 72 h after experimental gill inoculation. Fish were inoculated with 2.6×10⁶ or 5.0×10⁶ CFU/fish, which caused low and high mortality, respectively. Within 48 h, fish inoculated with the 2.6×10⁶ dose were culture positive on the gill surface, blood of the first and second gill arches, blood of the third and fourth gill arches and the nares. However, for the dose of 5.0×10⁶ CFU/fish, S. iniae was also isolated from the olfactory, optic and cerebellum regions of the brain, eye, head kidney, trunk kidney, spleen and liver at 48 h. For the 2.6×10⁶ dose, S. iniae was not isolated until 48 h post-inoculation, but was isolated at 12 h for the 5.0×10⁶ dose. The results of this study indicate that S. iniae can enter hybrid striped bass through the gills. However, mortality at similar S. iniae doses was lower than we previously observed by inoculation of the nares.     

Bacterial diversity of tilapia (Oreochromis niloticus) cultured in brackish water in Saudi Arabia

The bacterial flora occurring in brackish pond water, sediment, gills and intestine of healthy tilapia cultured in Saudi Arabia were estimated both quantitatively and qualitatively, and the isolates were identified to genus or species level. Total viable count of bacteria ranged from 1.4±1.5×10³ to 8.6±2.7×10³ cfu ml⁻¹; 1.2±3.1×10⁶ to 7.3±1.1×10⁷ cfu g⁻¹; 8.7±1.9×10⁵ to 2.1±0.9×10⁶ cfu g⁻¹; and 2.8±2.4×10⁷ to 1.0±1.6×10⁸ cfu g⁻¹ in the pond water, sediment, gills and intestine of brackish water tilapia, respectively. In total, 19 bacterial species were identified. The bacteria were predominantly Gram-negative rods (87%). Pond water and sediment bacteria influenced the bacterial composition of gills and intestine of tilapia. In contrast to gill bacteria, more diversification was observed in intestinal bacteria. The predominant (prevalence >10%) bacterial species were Vibrio parahaemolyticus, Vibrio carchariae, Vibrio alginolyticus, Chryseomonas sp., Vibrio vulnificus, and Streptococcus sp. in all the populations with the exception of the sediment population where Streptococcus sp. was replaced by Shewanella putrefaciens. Vibrio spp. (58% of the total isolates) dominated the total bacterial population.     

Loma salmonae (Protozoa: Microspora) infections in seawater reared coho salmon Oncorhynchus kisutch

Loma salmonae (Putz et al., 1965) infections were observed in five groups of coho salmon, Oncorhynchus kisutch, reared in seawater net-pens in Washington State, U.S.A. in 1984–1986. Ultrastructural characteristics, size of spores, tissues and host infected, and geographical location identified the microsporidium as Loma salmonae. Preserved spores measured 4.4×2.3 (4–5.6×2–2.4) μm and exhibited 14–17 turns of the polar filament. Infections were evident in the gills of some fish before seawater entry, but few parasites were observed and they caused little tissue damage. Infections observed in fish after transfer to seawater were associated with significant pathological changes in the gills. A mixed inflammatory infiltrate was associated with ruptured microsporidian xenomas within the vessels and interstitium of the primary lamellae. Microsporidian spores were dispersed throughout the lesions and were often seen inside phagocytes. The parasite was also observed in the heart, spleen, kidney and pseudobranchs; however, the inflammatory lesions were common only in the heart.

Monthly examination of fish after transfer to seawater showed peak prevalences (33–65%) of gill infections during the summer. Although moribund fish were often infected with other pathogens, the high prevalence of L. salmonae infections and the severity of the lesions it caused, suggested that this parasite significantly contributed to the recurrent summer mortalities observed at this net-pen site.     

从许氏平鲉体表分离海分枝杆菌的鉴定及其脂多糖的抗原性分析

从许氏平鲉粘液、背鳍、鳃等部位分离筛选到同一菌株FZ09,经形态学观察、生理生化特性及热激蛋白65(HSP65)基因序列分析,鉴定菌株FZ09为海分枝杆菌。分别用酚-氯仿-甲醇法、乙醇-酚水法和传统热酚水法提取菌株FZ09的脂多糖(LPS),分析了LPS的组成和抗原性差异。SDS-PAGE结果表明,3种方法提取的LPS条带分布基本相同,主要条带分子量分别为14、16和23 ku,其中以乙醇-酚水法提取的LPS含量和纯度最高,热酚水法提取的LPS条带最多,抗原性最好。Western-blotting显示,海分枝杆菌抗血清主要与LPS的14 ku条带发生特异性免疫反应。高碘酸氧化免疫印迹结果表明,仅传统热酚水法提取的LPS在14 ku分子量区域有弱的阳性条带出现,其他方法提取LPS与抗血清的免疫反应呈阴性。高碘酸氧化ELISA反应显示,LPS经高碘酸氧化后与海分枝杆菌FZ09抗血清的反应活性降低,OD₄₀₅明显减弱。     

Efficacy of bath vaccination with a live attenuated Vibrio harveyi against vibriosis in Asian seabass fingerling,Lates calcarifer

Vibrio harveyi causes vibriosis in various marine aquaculture fish species, especially when they are young. The infection subsequently leads to significant economic losses for aquaculture farms. Vaccination is recommended to control this disease. This study describes the efficacy of a live attenuated V. harveyi strain MVh_vhs (LAVh) as a vaccine candidate in controlling infection by wild‐type V. harveyi (WTVh) in Lates calcarifer. A total of 240 fingerlings were divided into four groups. Group 1 was not vaccinated and was not challenged, Group 2 was vaccinated with a formalin‐killed V. harveyi (FKVh), Group 3 was vaccinated with the LAVh before challenge and Group 4 was not vaccinated and was challenged. Bath vaccination was employed for one hour before the LAVh distribution was determined in the fish mucus, gill, liver, gut, kidney and spleen. The gills, livers, kidneys and skins were also sampled for gene expression analysis. To challenge the fish, skin abrasion was conducted before the fish were challenged by immersion with WTVh. The results revealed an extensive distribution of the LAVh in the liver and kidneys of the fish in Group 3 for the first 12 hr, resulting in mild lesions compared with Group 1. Similarly, there were significantly (p < .05) higher expressions of the Chemokine ligand 4 and major histocompatibility complex I genes in the skin and liver of the fish in Group 3 in comparison with other groups. Vaccination with LAVh resulted in a significantly high rate of survival (68%) of the fingerlings after being challenged with WTVh.     

Susceptibility of corkwing wrasse Symphodus melops, goldsinny wrasse Ctenolabrus rupestis, and Atlantic salmon Salmo salar smolt, to experimental challenge with Vibrio tapetis and Vibrio splendidus isolated from corkwing wrasse

The virulence of two Vibrio strains, previously isolated from diseased corkwing wrasse Symphodus melops and identified as V. tapetis and V. splendidus, to corkwing and goldsinny wrasse Ctenolabrus rupestris and to Atlantic salmon Salmo salar, was studied under laboratory conditions. Both bacteria were shown to be opportunistically pathogenic to corkwing wrasse, causing significantly higher mortality in the challenged groups than in the controls. Bacterial cultivation of kidney samples and re-isolation of V. tapetis and V. splendidus from most mortalities confirmed the two strains as the probable cause of mortality in the challenged groups. The control group also suffered relatively high mortality, but no specific pathogens that were suspected to be the main cause of death were isolated, other than a mixture of Vibrio spp. and, in the case of one individual, atypical Aeromonas salmonicida. Following injection challenge with both bacterial strains, no mortality was recorded in Atlantic salmon. In bath challenge trials with goldsinny wrasse, only slight mortality was observed in the challenged groups and the unchallenged control group. Bacterial examination showed that atypical Aeromonas salmonicida was the probable cause of death in both bath challenged and control groups of goldsinny wrasse, and no indication of infection by any Vibrio sp. was found.     

Identification of the adherent microbiota on the gills and skin of poly‐cultured gibel carp (Carassius auratus gibelio) and bluntnose black bream (Megalobrama amblycephala Yih)

PCR‐denaturing gradient gel electrophoresis (DGGE) was applied to analyse the microbial community attached to the gills and skin of poly‐cultured gibel carp (Carassius auratus gibelio) and bluntnose black bream (Megalobrama amblycephala Yih) and compare these results with those detected in the rearing water. The microbiota discussed included bacteria, fungi and a specific bacterial taxa of actinomycetes was also analysed. Proteobacteria, Firmicutes, Actinobacteria, Cyanobacteria, Ascomycota, Basidiomycota and some unclassified microbiota were identified. Based on our results, we concluded that: (1) the adherent bacterial/fungal communities on the gills and skin were different from those in the rearing water, (2) the bacterial/fungal diversities on fish gills were lower than that on fish skin, (3) the adherent bacterial/fungal communities on gill and skin of gibel carp were different from that of bluntnose black bream and (4) the adherent actinomycetal community showed certain similarity between the skin of different hosts. Based on our conclusions, we suggested that the topic investigated in the present study merits further investigations.     

鲤浮肿病毒人工感染锦鲤的试验研究

为研究鲤浮肿病毒的感染方式及在锦鲤各组织器官中的动态分布,在水温20～22℃,溶解氧7～8mg/L试验条件下,采用注射、浸泡、划伤后浸泡3种方式人工感染锦鲤,观察了试验鱼的发病和死亡情况;检测了鲤浮肿病毒在感染鱼体内各组织器官中的存在情况,探讨了主要被感染组织的病理变化。试验结果显示,采用注射、浸泡、划伤后浸泡3种方式均可导致健康锦鲤感染该病毒,病鱼出现昏睡、烂鳃、凹眼等症状,累积死亡率35%～88%。锦鲤感染该病毒后至少有3d的潜伏期,随后病毒在鳃组织中大量增殖,至7d达到高峰,病毒量314.8个/ng,之后病毒量开始逐渐下降,至12d在鳃组织中检测不出病毒。鲤浮肿病毒在肾、肝、脑、肌肉和脾中存在的时间较短且病毒量较低,在血液和肠道中未检出。结合鳃组织病理切片可知,鳃为该病毒感染的主要靶器官。本研究结果为鲤浮肿病的诊断和防控提供了一定的科学依据。     

Immunization of grouper, Epinephelus coioides, confers protection against a protozoan parasite, Cryptocaryon irritans

The present study aimed to determine whether protection is conferred by immunization of grouper, Epinephelus coioides, against a protozoan parasite, Cryptocaryon irritans. The immunization of E. coioides was carried out by a low level exposure of fish to live C. irritans theronts from predetermined number of tomonts and by an intraperitoneal injection of a vaccine consisting of formalin-killed C. irritans theronts.

Mucus titers detected by ELISA were significantly higher in fingerling and adult grouper subjected to the low level of exposure to C. irritans theronts at 3-week post-exposure compared to fish that had no previous exposure. In addition, significantly smaller tomonts were produced from adult grouper after three successive exposures than the tomonts produced after a single exposure to the parasite.

In the vaccine-immunization experiment, no mortality was monitored in fish that received high dose vaccine (100 μg/fish), while 40% cumulative mortality and 100% cumulative mortality were recorded in low dose group (10 μg/fish) and control group (PBS-injected), respectively. In the succeeding replicate, the vaccine-immunized group (high dose) had 37.5% cumulative mortality and 100% cumulative mortality for the control. In addition, a total of 1830 tomonts were collected at 5-day post-challenge from the control group while none from the vaccine-immunized group. Significantly fewer trophonts and tomonts were enumerated at 5-day and 7-day post-challenge, respectively, in the vaccine-immunized group than the control.

Results suggest that a protective immunity has been conferred on the immunized grouper as indicated by high antibody titers in the mucus of C. irritans-exposed fish and higher survival and fewer parasites in vaccine-immunized fish than the control groups. The conferred immunity played a major role in preventing or limiting the adhesion, invasion, and development of C. irritans theronts on the skin of the immunized grouper.     

用绿色荧光蛋白标记的细菌研究鱼体吸收颗粒抗原的部位

用绿色荧光蛋白标记的嗜水气单胞菌４３３２株（Ａｈ４３３２＾ＧＦＰ）菌液高渗浸泡和直接浸泡异育银鲫,研究鱼体对颗粒抗原的吸收。经两种方法处理的鱼,在整个实验过程中显示,鱼鳃的标记菌检出量均高于皮肤和肠道中的标记菌,证实鳃是抗原吸收的主要部位。另外,鱼体经高渗处理,鳃和皮肤可检出的标记菌明显增加。在肠道中,除浸泡６０ｍｉｎ,浸泡１０ｍｉｎ、３０ｍｉｎ及１２０ｍｉｎ的细菌检出量也明显增加。显示高渗可促进抗原的吸收。     

暗纹东方鲀非01霍乱弧菌的鉴定及毒力基因检测

在对养殖暗纹东方病害调查中，从呈典型症状病鱼腹腔和肠道粘液中分离到2株（J-1和H-3）菌株，经生化特性和血清型鉴定为非01群霍乱弧菌(Non-01 Vibrio cholerae)。注射、创伤和浸泡3种方式进行人工感染试验表现出较强的致病性，出现症状与自然发病鱼相同。为进一步确认分离菌株的分类地位，使用P1、P2引物，以非01群霍乱弧菌N92001菌株和01群霍乱弧菌N16961菌株为对照，对分离菌株进行PCR扩增，得到451bp的DNA片段。根据现有霍乱弧菌肠毒素ctxA基因序列设计引物P3,P4，以N16961菌株为阳性对照，PCR扩增结果均得到大小为400 bp的DNA片段。在对H-3菌株的扩增片段进行纯化、克隆和测序，得到407bp序列，该菌株与N16961菌株中肠毒素ctxA基因序列的完全一致，证实该片段源于ctxA基因。进一步说明从暗纹东方体内分离到的J-1和H-3菌株具有霍乱肠毒素ctxA，有一定的致病力。     

Bactericidal activity of cecropin B and cecropin P1 expressed in fish cells (CHSE-214): application in controlling fish bacterial pathogens

Cecropins are a group of antimicrobial peptides which have bactericidal activity against a broad range of bacteria. To date, the cecropins used in a variety of studies were either purified from their natural source or obtained by chemical synthesis. The present study was conducted to test whether bactericidally active cecropins could be expressed in a fish cell line. For this purpose, Chinook salmon embryo cells (CHSE-214) were transfected with cecropin transgene constructs: Hyalophora cecropia preprocecropin B, procecropin B, cecropin B, and porcine P₁ cecropin. From the transfected cells, single cell clones were selected and screened for the presence of cecropin gene constructs by PCR amplification. The expression of the cecropin transgene in the PCR positive clones was determined by RT-PCR reaction. Southern blot hybridization results showed that the cecropin gene constructs were integrated into the genome in a multiple integration pattern. Bactericidal activity of the cecropins, synthesized from transgene constructs, was detected using inhibition zone assay for fish pathogenic bacteria: Aeromonas hydrophila, Pseudomonas fluorescens, and Vibrio anguillarum. Cecropin antimicrobial peptides produced in CHSE-214 cells possess bactericidal activity against these three fish pathogenic bacteria.     

Comparative challenge model of Flavobacterium columnare using abraded and unabraded channel catfish, Ictalurus punctatus (Rafinesque)

The early entry of the fish pathogen Flavobacterium columnare and enhancement by abrasion was studied in channel catfish, Ictalurus punctatus (Rafinesque), using the polymerase chain reaction and a species-specific primer set for a bacterial 16S rRNA gene product. Evaluations were conducted following an abrasion bath immersion challenge with F. columnare. Abrasion, a practice which has historically been used prior to bacterial challenge, had significant effects on the early entry of the pathogen and on cumulative percent survival (CPS). The FvpF1-FvpR1 primer set was useful in detecting the early entry of F. columnare in mucus, skin, gill, blood, liver and trunk kidney tissues in both abraded and unabraded fish following immersion challenge at 29 +/- 2 degrees C. Bacteria were detected earlier in all tissues in abraded fish, except in the trunk kidney. These differences were not significant, except in the case of blood. Mucus, skin and gill tissues were positive for F. columnare earliest regardless of treatment (after 5 min in abraded fish and after 15 min in unabraded fish). CPS following challenge with F. columnare was significantly affected by abrasion, which supports the use of abrasion for the F. columnare challenge model for channel catfish.     

Pinpointing the role of Aeromonas salmonicida in the development of skin ulcerations in common dab (Limanda limanda)

Aeromonas salmonicida was isolated from ulcerations in common dab (Limanda limanda). An experiment was performed to pinpoint its role in ulceration development, considering the importance of the skin barrier and the pigmented and non-pigmented sides. The skin of dab was treated in three zones, one where scales and epidermis were removed, one where mucus was discarded and one non-treated zone. Fish were tagged to allow individual identification and challenged with A. salmonicida. Mortality and severity of the developing lesions were recorded for 21 days post-inoculation. Starting 12 days post-inoculation, mortality occurred gradually in challenged fish; however, no direct cause could be established. Both control fish and challenged fish developed ulcerations containing A. salmonicida. Sequencing of vapA gene revealed that isolates retrieved from both groups were distinct, suggesting the presence of A. salmonicida prior to the trial. Most ulcerations developed in zones where skin was removed, suggesting that abrasion might be a predisposing factor in ulceration development. Ulcerations were also observed at the insertion site of the tag, where exposed muscle tissue might have favoured the development of ulcerations. In conclusion, A. salmonicida seems to be involved in the development of skin ulcerations in dab, although the exact pathogenesis needs to be elucidated.     

大弹涂鱼皮肤黏液的抑菌活性和蛋白质组学

皮肤黏液是鱼类免疫防御的第一道防线。大弹涂鱼皮肤黏液对其免疫防御、渗透压维持以及适应水陆生活等方面具有重要意义。为深入了解大弹涂鱼皮肤黏液的蛋白质分子组成,对其皮肤黏液开展了抑菌活性分析和蛋白质组学分析。通过电刺激法收集大弹涂鱼皮肤黏液,采用打孔法比较了皮肤黏液和血清的抑菌活性差异;进一步利用鳗弧菌对大弹涂鱼进行诱导,采用生长曲线抑制法分析和比较了诱导前后皮肤黏液的抑菌活性差异。利用Shotgun质谱技术,结合大弹涂鱼皮肤转录组数据库,对大弹涂鱼皮肤黏液开展了蛋白质组学分析;进一步利用String软件对所鉴定的蛋白质开展了蛋白质相互作用预测。大弹涂鱼皮肤黏液具有广谱抑菌活性,鳗弧菌诱导后的大弹涂鱼皮肤黏液与诱导前相比,对部分革兰氏阴性菌的抑菌活性明显上升,但对其他菌株的抑菌活性差异不明显。从大弹涂鱼皮肤黏液中共鉴定各类蛋白质分子97种,基本分子组成与其他硬骨鱼类皮肤黏液蛋白相似,但也有少数蛋白如泛素蛋白、胸腺素蛋白等未在其他鱼类皮肤黏液中报道。此外,其他鱼类中所鉴定到的部分蛋白如热休克蛋白、抗菌肽等在大弹涂鱼皮肤黏液中未能鉴定到。大弹涂鱼皮肤黏液中已鉴定的蛋白多数具有与免疫功能相关的结构域,且存在一个以肌动蛋白为核心的相互作用网络。大弹涂鱼皮肤黏液具有明显的广谱抑菌活性,其蛋白质组成与其他鱼类皮肤黏液具有一定的相似性。本研究为深入了解大弹涂鱼皮肤黏液的分子多样性及功能机制奠定了基础。     

Aeromonas salmonicida infection in wrasse (Labridae), used as cleaner fish, on an Atlantic salmon, Salmo salar L., farm

Abstract. Typical Aeromonas salmonicida with similar biochemical characteristics to A. salmonicida from Atlantic salmon, was isolated from wrasse, Ctenolabrus rupestris (L.) and Centrolabrus exoletus (L.), stocked as cleaner fish with these salmon. Although no external clinical signs were apparent, localized bacterial microcolonies were observed in muscle, gills, intestine, kidney and myocardial tissue. Mortalities attributed to A. salmonicida comprised 55% (n = 32) of total mortalities. No carriers of A. salmonicida were found in wild wrasse following stress testing. Although salmon post-smolts died when challenged with 1 × 10⁵ ml^-1 of a virulent strain, there were no mortalities in challenged wrasse. An oral route of infection is suggested rather than water-borne transfer as wrasse browsed on salmon mortalities. Wrasse were treated for A. salmonicida infection by injection with antibiotic and were also vaccinated, and in the latter case, elevation of antibody levels was noted.