Rewaida Abdel-Gaber*, Fathy Abdel-Ghaffar, Abdel-Rahman Bashtar, Kareem Morsy Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt Corresponding author E-mail:
[email protected]
Introduction
Results
A variety of organisms have been investigated to evaluate their potential as biological indicators for different types of pollution in the environment. The relationship between pollution and parasitism in aquatic organisms has received increasing attention during the past two decades. Fish considered as one of the most important sources of animal protein all over the world. Different species of parasites are subjected to infect a variety of freshwater and marine fish.
Objectives The present study aimed to determine: 1- The exact taxonomic position of Hysterothylacium aduncum parasitizing Solea solea by morphological and molecular analyses. 2- If this anisakid is a useful bio-indicator species for water pollution or not.
Figs. 2–9 Photomicrographs for different body parts of the adult Figs. 10–16 Scanning electron micrographs for the adult nematode parasite H. aduncum. nematoda parasite H. aduncum. Abbreviations: Lips (L), interlabium (IL), papillae (P), cuticle (C), esophagus (OE), transverse striations (TS), spicules (SP), short mucron (M) , rectum (R), and anal region (A).
Methods and Methods A total of 80 specimens of the common sole S. solea (F: Soleidae) were captured from coasts of Alexandria City, Mediterranean Sea, Egypt. The fish were transported to Laboratory of Parasitology Research at Zoology Department, Faculty of Science, Cairo University, Egypt; to be examined for endo-parasitic infections. Fig. 17 Dendrogram showing phylogenetic relationship between the present H. aduncum and other species belonging to the family Anisakidae. Table 1 Concentration of heavy metals (mean±SD, mg/g) in different organs of the infected fish as well as in their parasitic nematode worms
Fig.1 Photograph of the common sole Solea solea
For light microscopy, the recovered nematode were fixed in 70% ethanol, then cleared in lactophenol and photographed by help of a Zeiss microscope supplied by a Canon digital camera. For electron microscopy, samples were fixed in 3% glutaraldehyde solution, dehydrated in an ethanol series, coated by gold, then finally examined and photographed using an Etec Autoscan Jeol SEM under an accelerating voltage of 20 Kv. For molecular analysis, DNA was extracted by using a QIAamp® DNAMini Kit (Quiagen, GmbH, Germany). PCR products were amplified and sequenced by using specific primers which were NC5 (5’-TAGGTG AACCTGCGGAAGGATCATT-3’) and NC2 (5’-TTAGTTTCTTTTCCTCCGCT3’). The dendrogram built up by using the multiple alignment algorithm in MEGALIGN (DNASTAR, W.V. 3.12e). For Biochemical analysis, Heavy metals in different organs of infected, as well as in their parasitic nematode tissues were analyzed according to UNEP/FAO/IOC/ IAEA (1984).
Conclusion Recent field study demonstrated that: 1- 18S rDNA gene of H. aduncum yielded a unique sequence that confirms its taxonomic position in Raphidascarididae with a new host and locality records in Egypt. 2- This particular fish nematode parasites can accumulate toxic metals from the aquatic environment higher than their hosts. Thus, the application of certain parasites as sentinel organisms could provide a promising new domain for future research in environmental topics.
Acknowledgment
Authors need to send their appreciations to Faculty of Science, Cairo University, Egypt; for helping to complete this work.
