Abstract:
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Protein polymorphism and allelic variation were investigated
in the blood of the cat¢sh, Synodontis schall
(Bloch-Schneider,1801) and S. serratus (Ruppel,1829)
from three localities along the White Nile. The ¢rst
sampling locality at khartoum, the second at Jebel
Aulia Dam, 45 km south of khartoum and the third
locality was 45 km southward along theWhite Nile.
Seventeen gene loci were identi¢ed in separating 13
enzymes and proteins. Nine loci were polymorphic
and eight were monomorphic in the two species.
Two alleles were observed for each polymorphic locus.
Except for serum albumin (ALB ) and erythrocyte
glucose phosphate isomerase (GPI-1 ), all
corresponding allozymes in the two species revealed
similar mobilities and separation patterns. Serum albumin
(ALB ) was monomorphic with a molecular
weight of 67 kd in S. schall and 60^62 kd in S. serratus.
Glucose phosphate isomerase (GPI-1 ) was polymorphic
in S. schall, but monomorphic in S. serratus.
Acontingency (w2) test shows signi¢cant interspecies
heterogeneity in allele frequency at (haemoglobin
(HB )), (6-phosphogluconate dehydrogenase
(6PGD )) and (superoxide dismutase (SOD )) but
none of the other polymorphic loci. Average heterozygosity
was (0.26) for both species and the genetic
distance between the two species was (0.22). |