Abstract
The aim of this study was to identify Saprolegnia spp. isolated from inffected common carp Cyprinus carpio L. eggs and fry in two fish hatcheries (Al-Manahel and Al-Wahda) in the middle part of Iraq, during the period from March-June 2009. It was evident from molecular diagnosis (PCR Technique) that isolates of the genus Saprolegnia, shared one feature (production of secondary zoospores with long hooked hairs). These isolates were divided into four groups based on the findings of molecular diagnostics PCR. Isolates of Saprolegnia spp. were characterized genetically and physiologically. The majority (25 from45) of the isolates in both hatcheries were almost genetically identical as assessed by RAPD-PCR. The remaining isolates belonged to three different groups.
Highlights
Today, molecular methods, especially polymerase chain reaction )PCR) coupled with restriction fragment length polymorphism analysis )RFLP) is one of the most important methods to identify different Saprolegnia species and it could distinguish S. parasitica from S. diclina
Random amplification polymorphic DNA (RAPD) profiles obtained in this study revealed a genetic variation among Saprolegnia isolates from carp fish isolates and from water, eggs and fry from both hatcheries and separated the isolates into four different groups, such variables lead to separate the isolates to four groups, group 1 contained isolates, indicating that the group of closely related strains
This spread of a group of closely related strains came in agreement with [19] whom compared different isolates of Saprolegnia parasitica from trout by the RAPD-PCR technique and demonstrated that a group of closely related strains were spread over a large area and isolated from each other in well-separated water systems
Summary
Molecular methods, especially polymerase chain reaction )PCR) coupled with restriction fragment length polymorphism analysis )RFLP) is one of the most important methods to identify different Saprolegnia species and it could distinguish S. parasitica from S. diclina. Using random amplified polymorphic DNA-PCR (RAPD-PCR) which has been described by [1] in this technique, single or a pair wise combination of primers, typically 9-10 nucleotides in length, are used to amplify target genomic DNA by polymerase chain reaction (PCR). Amplified polymorphic DNA (RAPD) analysis seemed to be efficient in distinguishing different isolates; it has a high discriminatory power, it is easy to perform, does not require radiolabel led probes, and it is applicable to several microorganisms [2]. There are other techniques to study the genetic diversity of Oomycete pathogens and reveal population structures [4,5].
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