الفهرس 
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Abstract
In the current study, three duck breeds (Baladi, Pekin, and Soudani) occurring in Egypt were cytologically studied in order to define the karyotypic similarities and dissimilarities among them. The study was extended to cover the phylogenetic relationship and verify the taxonomical situation of Baladi breed based on molecular analysis using ten SSR markers.
1. Cytological studies
1. 1. Karyotype analyses
In order to characterize the karyotype variation among the studied duck breeds (Baladi, Pekin, and Soudani) , the largest eight chromosomes (including ZW) were recognized as macrochromosomes. The remaining 32 pairs which appear as dots under light microscope were classified as micro- chromosomes. Generally, there were no significant differences in the total lengths (5.652, 6.454 and 6.744 µm) of the largest chromosomes pair nos. 1, 2, 3, 4, 5, 6, 7, z and w between Balady, Pekin and Soudani duck breeds. In addition, the other karyotypic measurements such as lengths of the long and short arms and arm ratio of the analogous chromosomes have similarly shown no significant differences.
Data analyzed by KaryoType software showed that the centromere positions of chromosome nos. 3, 5, 6 were metacentrics in Pekin breed, while those of Baladi and Soudani were submetacentrics. It also showed that chromosome no.7 was metacentric and subtelocentric Z chromosome in Baladi, while those of Pekin and Soudani were submetacentrics.
1. 2. Variation of karytypic formula
Three different categories of karyotypic formula (1m+7sm+1st, 3m+6sm and 9sm) were observed in Baladi, Pekin and Soudani breeds, respectively. Values of karyotypic asymmetry ranged from 62.98% to 68.14% and were evidently different among the studied breeds. Likewise, Data indicated that the intra chromosomal asymmetry degree (AsD) diverse among the three breeds (3C in Baladi; 1C in Pekin and 3C in Soudani).
1. 3. G-banding of three duck breeds
Data obtained from banding patterns and G-banding physical mapping on p arm or on q arm of macro-chromosome pair no.1 in Soudani breed were clearly different from those found in Baladi and Pekin. Similarly, the other six large autosomes (somatic macro-chromosomes nos. 2 to 7) showed variable banding numbers and patterns across the three studied duck breeds.
2. Molecular studies
2. 1. Microsatellite (SSR) markers
Ten microsatellite (SSR) markers (APH11, APH17, APH18, APH21, CAUD019, CAUD024, SFIMU-1, TTUCG-1, TTUCG-2 and TTUCG-4) were used to amplify genomic DNA from four individuals for each breed. The obtained data revealed that all the ten SSR primers used in the present study produced scorable amplified fragments. The number of amplified bands per primer ranged from 2 of APH17 and TTUCG-1 primers to 10 bands from APH21 primer with a total number of 46 bands. from 46 generated bands only 37 were polymorphic. Among all tested SSR primers, TTUCG-2 did not produce any monomorphic fragments and generate 6 polymorphic fragmaents with 100% polymorphism. In addition to, the percentage of polymorphism which identified by SSR primers were varied from 50% at (APH17and TTUCG-1) to 100% at (TTUCG-2). The SSR amplicons generated by TTUCG-2 primer only exhibited 100% polymorphism among all studied duck breeds, while the two primers (APH17, TTUCG-1) revealed 50% polymorphism.
2. 2. Cluster analyses of studied Duck breeds on the basis of polymorphisms
A total of 46 polymorphic bands were used to assess the genetic diversity between the three studied breeds, data revealed that, there were two major clusters generated in the dendogram of genetic distance among the three studied duck breeds. Baladi duck breed formed the first cluster and Soudani and Pekin formed the second major cluster. Cytogenetical and molecular Data reported herein showed that Baladi breed is genetically farthest from the Pekin and Sudani breeds.