Fragility in X-chromosomes in Sahiwal (Zebu) cattle

Fragile site (FS) is a region in mitotic chromosome and at metaphase lacks the normal compaction of chromatin, which can be visible as constriction, break or gap.Cytogenetic examination followed by DNA primers amplification were used to study FS in 27 Sahiwal females inflicted with fertility problems (repeat breeding (17) and abortion (8)) both (2) along with 10 control normal fertile females.Chromosomes were examined with three different culture media conditions: RPMI-1640 with Aphidicolin (APH), TC-199 without folic acid and Ham's F-10 as a control medium.FSs were detected on different locations in X-chromosomes.In problematic animals percentage of metaphases showing FSs ranged from 17.14 to 28.79 while in control group the range was 7.89 to 10.76.Three media used revealed different frequencies of FSs on X-chromosomes.Significant revelation of FS was shown by RPMI-1640 with APH and TC-199 without folic acid as compared to Ham's F-10.Confirmation of FSs was done with specific seven DNA primers.FSs were found significantly associated with reproductive problems viz.repeat breeding, abortion and incidence of both in the same animals.