IJA Volume 60, Issue 4, 2008

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    Genetic Diversity and Population Structure of the Peanut Worm (Sipunculus nudus) in Southern China as Inferred from Mitochondrial 16S rRNA Sequences
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Xiadong, Du ; Zian, Chen ; Yuewen, Deng ; Qingheng, Wang ; Ronglian, Huang
    Genetic diversity and population structure of the peanut worm (Sipunculus nudus) were investi- gated by using 536 base-pair fragments of the mitochondrial 16S ribosomal gene. Populations were collected from three locations along the southern coast of China - Beihai, Sanya, and Xiamen. Amplified polymerase chain reaction products were sequenced in both directions and data were analyzed using ClustalX, Arlequin, and MEGA. A total of 69 polymorphic sites and 21 distinct haplotypes were revealed. The mean haplotype and nucleotide diversity of the three pop- ulations were 0.814% and 0.37%, respectively. The Beihai population had the greatest haplo- type and nucleotide diversity, followed by the Xiamen and Sanya populations. Analysis of mole- cular variance (AMOVA) showed significant genetic differentiation among the three populations (Fst = 0.0619, p<0.05) and distinct population structures among the three sites.
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    Optimal Dietary Protein Levels in Juvenile Electric Blue Cichlid (Sciaenochromis fryeri)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Gullu, Kenan ; Güroy, Derya ; Celik, Ihsan ; Tekinay, Adem
    A feeding trial was conducted to determine the dietary protein requirement of juvenile electric blue cichlids (Sciaenochromis fryeri). Groups of fish (0.50±0.01 g) were fed one of four isocaloric diets containing protein levels ranging 35-50% for 12 weeks. According to the broken-line model, the dietary protein requirement was estimated as 38.8%. The feed conversion ratio ranged from 1.73 in the 50%-protein group to 2.16 in the 35% group. There were statistically significantly dif- ferences in feed intake and protein efficiency ratio. In general, the protein efficiency ratio decreased as the dietary protein level increased. For optimum growth, feed conversion, and pro- tein utilization, a diet containing 39-40% protein, 11% crude lipid, and 20.7 MJ gross energy/kg diet is recommended for juvenile S. fryeri.
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    Digestive Enzymes and Hormones in Gilthead Seabream Larvae (Sparus aurata) Fed Artemia Nauplii Enriched with Free Histidine
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Naz, Mehmet ; Turkmen, Mustafa
    The digestive enzymes and hormones of gilthead seabream (Sparus aurata) larvae fed live prey (Artemia nauplii) enriched with free histidine were investigated for 16 days (from day 24 to day 40 after hatching). Larvae were sampled at 4-day intervals. The control group had significantly lower growth than the enriched group (p<0.05). Trypsin activity was higher in the control (p<0.05). Bombesin activity significantly differed between treatments, periods, and period x treatment interac- tions and the cholecystokinin level was significantly higher in the enriched groups (p<0.05). Results indicate that Artemia nauplii can successfully be enriched with free histidine, bombesin and chole- cystokinin activity can be stimulated by free histidine, and mechanisms controlling the adaptation of trypsin activity to the amount of dietary protein were not activated within the 40-day study period.
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    Comparison of Periphyton Grown on Different Substrates as Food for Organic Tilapia Culture
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Milstein, Ana ; Peretz, Yakov ; Harpaz, Sheenan
    Regulations regarding organic tilapia culture result in increased feed costs. To reduce such costs, experiments were conducted to enhance the natural production of periphyton, on which tilapia feed. Strips of substrates of different textures and colors were placed in the water column of tilapia culture ponds to induce periphyton growth. Some strips were placed in cages to protect them from fish grazing and some where placed in the open pond, accessible to the fish. Periphyton development was evaluated by the contents of chlorophyll, dry matter (DM), and ash free dry matter (organic matter) and by an autotrophic index. The first experiment tested growth on substrates of different textures including natural (palm leaves) and artificial (agricultural nets, plastic surfaces) materials. The second experiment tested the effect of different colored nets. The differences between periphyton grown in cages and in the open pond indicate that tilapia grazed on the periphyton. Palm leaves decomposed too quickly to be of practical use in large- scale aquaculture. Periphytic material seemed to be more easily dislodged from smooth plastic substrates than from rough nets, changing the structure of the residual attached periphyton. Growth was greater on nets with a fine mesh (5.3-9.6 mg/cm2 DM) than with a coarse mesh (3.7- 4.0 mg/cm2 DM) or on smooth plastic surfaces (1.4-2.6 mg/cm2 DM). The color of the substrate did not affect the chlorophyll content of periphyton but did affect its dry and organic matter con- tent. The white substrate had 40% more dry matter (11.5 vs 7.9-8.2 mg/cm2) and 50% more ash free dry matter (2.1 vs 1.4 mg/cm2) than the blue and black substrates.
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    Immunization of Rainbow Trout (Oncorhynchus mykiss) against Lactococcus garvieae Using Vaccine Mixtures
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Kubilay, A. ; Altun, S. ; Ulukoy, S. ; Ekici, S. ; Diler, O.
    The effectiveness of vaccine mixtures against lactococcosis was tested in rainbow trout (Oncorhynchus mykiss). The M1 strain of Lactococcus garvieae, isolated from a recent outbreak of lactococcosis at a rainbow trout farm in Turkey, was used in a trial comparing five immuniza- tion treatments: (a) formalin inactivated bacterin (vaccine), (b) the above bacterin together with Freund’s Incomplete Adjuvant (FIA), (c) the bacterin combined with β-glucan, (d) β-glucan only, and (e) phosphate buffered saline-PBS (control). Fish were given intrapritoneal injections and challenged by exposure to the bacteria 30, 75, or 125 days after vaccination. In fish exposed to the bacteria 30 days after injection, the relative percent survival (RPS) was 88.89% in the group that received only bacterin and 100% in the group that received the bacterin combined with FIA. Immunity remained high in the bacterin+FIA group, as the RPS in this group remained 100% in fish challenged at 75 days, significantly higher than in all other groups. In fish exposed to the bacteria 125 days after vaccination, the RPS was 54.55% in fish vaccinated with the bacterin only and 84.84% in fish vaccinated with bacterin+FIA. In the group that received only β-glucan, immunity did not improve after vaccination. Micro-agglutination tests of serums showed that immunized fish produced antibodies at high titers within 30 days. In short, the formalin-inacti- vated M1 strain provided longer lasting protection against Lactococcus garvieae in rainbow trout when combined with FIA than when administered alone or with β-glucan.
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    Screening Cage Culture Fish Species for Organic Chlorinated Pesticide and Polychlorinated Biphenyl Residues in Turkey
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Koc, Feride ; Gurel, Yasemin ; Yigit, Yusuf ; Atamanalp, Muhammed ; Kursad, Yavuz ; Kisa, Fikrullah
    Organic chlorinated compounds (aldrin, α-endosulfan, β-endosulfan, 2,4’-DDT, and 4,4’-DDE) and polychlorinated biphenyles (PCB28 and PCB52) were screened in fish culture cages off the Aegean Coast of Turkey. Sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) were randomly selected from three coastal areas during June-December 2004. Samples of 114 fish were analyzed by gas chromatography (GC) with an electron capture detector and GC-mass spectrometry (GC-MS). No residues exceeding limits established by the European Union Directive were detected. However, 4,4’-DDE was found in 2.63% of the samples. The amounts of residues in all positive samples were lower than the maximum tolerance limits (0.2-1 mg/kg) accepted by the EU Directive. Contamination levels varied with species, ranging 18-200 ng/g wet weight. Other chemicals were not detected in fish samples.
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    Detection and Identification of Fish Pathogens: What is the Future?
    (Israeli Journal of Aquaculture - BAMIGDEH, 2008) Frans, I. ; Lievens, B. ; Heusdens, C. ; Willems, K.A.
    Fish diseases pose a universal threat to the ornamental fish industry, aquaculture, and public health. They can be caused by many organisms, including bacteria, fungi, viruses, and protozoa. The lack of rapid, accurate, and reliable means of detecting and identifying fish pathogens is one of the main limitations in fish pathogen diagnosis and disease management and has triggered the search for alternative diagnostic techniques. In this regard, the advent of molecular biology, especially polymerase chain reaction (PCR), provides alternative means for detecting and iden- tifying fish pathogens. Many techniques have been developed, each requiring its own protocol, equipment, and expertise. A major challenge at the moment is the development of multiplex assays that allow accurate detection, identification, and quantification of multiple pathogens in a single assay, even if they belong to different superkingdoms. In this review, recent advances in molecular fish pathogen diagnosis are discussed with an emphasis on nucleic acid-based detec- tion and identification techniques. Major features and applications of current predominant meth- ods and promising methods likely to impact future fish disease control and prevention are out- lined.