- Tools
- Downloads
- Links
- Community
- About
- Help
FB2026_01
,
released March 12, 2026
Males carrying C(Y;4)cb25-1 show a high frequency of sex and 4th chromosome non-disjunction.
Causes a significant level (around 5%) of sex chromosome non-disjunction, presumably owing to the chromosome's dicentricity. Male fertility restored. This duplication-bearing Y chromosome is sensitive to action of SD.
Males carrying C(Y;4)cb25-1 and no other Y chromosome are fertile. They show an increased frequency of sex chromosome non-disjunction (14%) and of chromosome laggards (6%) in primary spermatocytes. Disruption of normal sex chromosome disjunction also occurs in females containing the C(Y;4)cb25-1 chromosome and a compound X chromosome; the frequency of exceptional progeny is 2.55% compared to 0.91% in controls.
Carries most of the fourth chromosome, including the centromere (see also Ault and Lyttle, Chromosoma 97:71-79 ).
break in h39-h40.
C(Y;4)cb25-1 is a transmissable dicentric chromosome which consists essentially of the entire Y and fourth chromosomes joined by 2R heterochromatin. The breakpoint of the Y is distal to all fertility factors on the long arm. The breakpoint on the fourth chromosome appears to be at 102F. The Y and fourth chromosomes are joined by 2R heterochromatin which contains Rsps, but has none of the lethal complementation groups in 2R heterochromatin described in FBrf0028786. This places the breakpoints of the second chromosomes on either side of Rsps.
The C(Y;4)cb25-1 chromosome pairs with the X and the free fourth chromosome to form a trivalent in meiosis that is unusual because it forms few chromosome bridges in primary spermatocytes and is transmitted at high frequency.