التعرف على الفصائل والشجرة الوراثية للقراد الصلب (Rhipicephalus) بواسطة التحليل الجيني الجزيئي من عدة محافظات فلسطينية مختلفة
رائدة سالم احميدان طقاطقة
Raida Salim Ihmeidan Taqatqa
Ticks are obligate blood-sucking hematophagous ectoparasites of terrestrial vertebrates, including amphibians, reptiles, birds, and mammals. Two general families of ticks are recognized: Argasid (soft ticks) and Ixodid (hard ticks).The family Ixodidae of hard ticks is divided into two groups based on morphological features: the Metastriata and the Prostriata. In the Ixodidae family the genera Ixodes, Amblyomma, Dermacentor, and Rhipicephalus are considered medically important. Among Rhipicephalus ticks, R. sanguineus, R. turanicus and R. bursa, are the most common species in Palestine. All three Rhipicephalus species are medically important vectors; therefore their accurate identification is necessary. Morphological identification of these species is difficult, especially when the specimens are damaged or engorged with blood or in on immature stage. The objectives of this study are to identify the most common hard-ticks species in Palestine, to establish a molecular approach for discrimination between hard ticks species that infest sheep, and dogs and to study the genetic variation within each species in comparison to local and foreign hard ticks species. By identification of hard tick species, the potential risk to animals as well as humans may be evaluated and thus more adequately controlled. A total of 351 hard ticks (Ixodidae) were collected from sheep, goats and dogs during March to October 2014. Ticks were identified based on morphological features into two main genus; Rhipicephalus (97.4%) and Haemaphysalis (2.6%). The ticks were further identified down to the species level as following: R. sanguineus (79.2%), R. turanicus (9.7%), R. bursa (3.4%), H. alderi (0.9%) and H. parva (1.6%). All tick samples were identified by polymerase chain reaction (PCR) targeting the COX-1 gene followed by RFLP using AluI restriction enzyme. A highly significant correlation was observed between RFLP and microscopy identification (p= 0.01). Phylogenetic analysis based onCOX-1 genetic sequences showed four main clusters, R. sanguineus-like cluster, R. turanicus -like cluster G1 and G2, and R. bursa-like cluster. This study is the first of its kind to identify the hard tick species, using COX-1 gene followed by RFLP as genetic marker. Distinction between the closely related Rhipicephalus species: R. bursa, R. turanicus and R. sanguineus was successfully accomplished.
الكيمياء الحيوية والاحياء الجزيئية , Biochemistry & Molecular Biology