scholarly journals Genetic variation in wild populations and farmed stocks of Nile tilapia (Oreochromis niloticus) in Madagascar

2019 ◽  
Vol 72 (3) ◽  
pp. 101
Author(s):  
Monique Ravakarivelo ◽  
Elodie Pepey ◽  
John A.H. Benzie ◽  
Noromalala Raminosoa ◽  
Harentsoaniaina Rasamoelina ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Wild Populations ◽  
Diversité Génétique ◽  
Variabilité Génétique ◽  
Il Y A

Quatre stocks issus de piscicultures et quatre populations sauvages de tilapias du Nil (Oreochromis niloticus), espèce qui a été introduite initialement à Madagascar il y a soixante ans, ont été évalués pour leurs variations génétiques à partir de l’analyse de neuf locus microsatellites pour déterminer les niveaux de variabilité génétique au sein des populations et les relations génétiques entre ces populations. La diversité allélique recoupait celle qui a été rapportée dans d’autres populations africaines. Il n’y avait ni évidence d’écart dans les fréquences alléliques attendues dans les conditions d’équilibre de Hardy-Weinberg ni de consanguinité dans les populations étudiées. Trois groupes génotypiques distincts ont montré trois introductions séparées (à partir d’Egypte et de l’île Maurice en 1956, et du Japon en 2011) et la présence de génotypes issus de plus d’un groupe dans une même population a fourni la preuve de mélanges. Il y avait des différences significatives entre les populations qui ne provenaient pas du même milieu (sauvage ou d’élevage) ou qui n’étaient pas géographiquement reliées. De par leur diversité génétique, les populations sauvages pourraient être des ressources intéressantes dans la perspective d’un développement de la pisciculture du tilapia du Nil à Madagascar. 

Genetic improvement of farmed tilapias: estimation of genetic variation and heritability for age and size at first spawning in Nile tilapia (Oreochromis niloticus)

Aquaculture ◽  
1995 ◽  
Vol 137 (1-4) ◽  
pp. 279-280 ◽  
Author(s):  
Ambekar E. Eknath ◽  
Ruben A. Reyes ◽  
Hernando L. Bolivar ◽  
Marietta P. De Vera ◽  
Jodecel C. Danting ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Oreochromis Niloticus ◽  
Genetic Improvement ◽  
Nile Tilapia ◽  
Nile Tilapia Oreochromis Niloticus

scholarly journals Microsatellite marker-based variation in the growth hormone genes of Nile tilapia (Oreochromis niloticus)

2020 ◽  
Vol 32 (1) ◽  
pp. 1-10
Author(s):  
Mst. Sadia Zafrin ◽  
Md Samsul Alam
Keyword(s):  
Growth Hormone ◽  
Genetic Variation ◽  
Microsatellite Loci ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Polyacrylamide Gel Electrophoresis ◽  
Fixation Index ◽  
Hatchery Stock ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Ethidium Bromide Staining

Polymorphisms in growth hormone genes have been found to cause variation in growth performance of fish. The objective of the study was to reveal variations in microsatellite loci located in the growth hormone genes of Nile tilapia (Oreochromis niloticus). Five microsatellite loci namely GH-MS01, IGFII, IGFII-MS01, IGFII-MS03, and STR were analyzed to assess the genetic variation in the growth hormone genes of four stocks of O. niloticus viz. FBG-Mini Hatchery, FM-Mini hatchery, Eon Aquaculture Ltd. and BFRI. The microsatellite markers were amplified by polymerase chain reaction, separated by polyacrylamide gel electrophoresis and visualized through ethidium bromide staining. All the five loci were found to be polymorphic. The average number of alleles of FM-Mini hatchery stock (3.8) was found to be highest and that of the FBG-Mini hatchery (2.8) and Eon Aquaculture stocks was found to be lowest. The average observed heterozygosity (Ho) value of the FM-Mini hatchery stock was the highest (0.140) and that of FBG-Mini hatchery stock was the lowest (0.040). On the other hand, the average expected heterozygosity (He) was highest in the BFRI stock (0.660) and lowest in the FM-Mini hatchery and FBG-Mini hatchery stock (0.432). The fixation index (1 - (Ho / He) values were positive in all the loci (except locus GH-MS01 in Eon Aquaculture stock), which means these stocks (O. niloticus) were deficient in heterozygosity. Deviation from Hardy-Weinberg expectation at STR locus in FBG-Mini hatchery and Eon Aquaculture stocks were not significant but in all other cases the deviations were found to be significant. The results provide evidence that genetic variation exists within the growth hormone genes in all four stocks of O. niloticus. The polymorphisms that have been detected in the present study can be used to study association with growth and thus selection of fast growing Nile tilapia in Bangladesh.  

The effect of vaccination in controling bacterial disease caused by Aeromonas hydrophila in nile tilapia (Oreochromis niloticus)

2014 ◽  
pp. 27
Author(s):  
Arne A Ratulangi ◽  
Reiny Tumbol ◽  
Hengky Manoppo ◽  
Henneke Pangkey
Keyword(s):  
Survival Rate ◽  
Aeromonas Hydrophila ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Bacterial Disease ◽  
Immersion Method ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Different Ages ◽  
Motile Aeromonas Septicaemia

This study aims to apply vaccination against bacterial disease. The purpose of vaccination is to trigger the immune respone both non-specific and specific of fish against bacteria Motile Aeromonas Septicaemia (MAS) caused by Aeromonas hydrophila. The vaccination for fish with different ages: 2-3 weeks and 5 weeks were done using immersion method. The fish were re-vaccinated (booster) after two weeks of the first vaccination. The survival rate was < 50 % for juveniles 2-3 weeks and > 50% for juveniles 5 weeks. Survival rate for juveniles 5 weeks was higher than juveniles of 2-3 weeks. This shows that organs of juveniles of 5 weeks were more complete than the 2-3 weeks juveniles. The age of fish is one of the important factors for successfully vaccination. Penelitian ini bertujuan untuk melakukan penerapan vaksinasi terhadap penyakit bakterial. Vaksinasi ditujukan untuk merangsang respon kekebalan non- spesifik dan spesifik pada tubuh ikan terhadap penyakit Motile Aeromonas Septicaemia (MAS) yang disebabkan oleh bakteri Aeromonas hydrophila. Vaksin diberikan pada benih ikan nila yang berbeda umur yaitu 2-3 minggu dan 5 minggu dengan menggunakan metode perendaman. Ikan divaksinasi ulang (booster) setelah 2 (dua) minggu dari vaksinasi yang pertama. Prosentase kelangsungan hidup < 50 % untuk benih umur 2-3 minggu dan > 50% untuk benih umur 5 minggu. Jumlah kematian benih umur 2-3 minggu lebih tinggi dari 5 minggu. Hal ini menunjukkan bahwa fungsi organ benih umur 5 minggu telah lebih lengkap dari pada benih umur 2-3 minggu. Umur ikan merupakan salah satu faktor penting penentu keberhasilan suatu kegiatan vaksinasi.

Incidence and molecular characterization of fungi and yeast isolated from cultured catfish and Nile tilapia

2020 ◽  
Vol 21 (3) ◽  
pp. 61-66
Author(s):  
Ola Hashem ◽  
Viola Zaki ◽  
Rawia Adawy
Keyword(s):  
Molecular Characterization ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Clarias Gariepinus ◽  
Fungal Species ◽  
High Rate ◽  
Fish Farms ◽  
Isolation And Identification ◽  
Penicillium Spp

Objective: To study the incidence and seasonal dynamics of different fungi affected freshwater fishes in Lake Manzala with molecular identification of the isolated fungi. Animals: 300 Nile tilapia (Oreochromis niloticus) and 300 catfish (Clarias gariepinus). Design: Descriptive study. Procedures: Random samples of Oreochromis niloticus (O. niloticus) and Clarias gariepinus (C. gariepinus) were collected from Manzala fish farms. Clinical and postmortem examination of fish was applied. Isolation and identification of different fungi were performed by conventional methods. Furthermore, the molecular characterization of isolated fungi was carried out. Results: C. gariepinus had a higher rate of infection with different fungal species than O. niloticus. Aspergillus spp. (Aspergillus niger and Aspergillus flavus) were the most fungal isolated from the examined fishes, followed by Penicillium spp. and Candida albicans. Aspergillus spp were detected in all seasons with a higher rate in summer and spring. A. flavus, A. niger, Penicillium spp. and C.albicans isolates were amplified from both C. gariepinus and O. niloticus at the specified molecular weight using PCR. Conclusion and clinical relevance: Fungal infection affected the fish showing different external and internal lesions, all species of Aspergillus were found in all seasons with a high rate in, hot seasons, summer and spring. The Prevalence of Penicillium and C. albicans were also reported. All fungal isolates were identified on the phenotypic and molecular bases.

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