Two new X-autosome translocations in the mouse.

Area of Science:

• Genetics
• Reproductive Biology
• Developmental Biology

Background:

• Reciprocal translocations can disrupt meiosis and cause infertility.
• Understanding chromosomal rearrangements is crucial for reproductive health and genetic studies.

Purpose of the Study:

• To characterize two reciprocal translocations, T(X;4)37H and T(X;11)38H, induced by X-irradiation.
• To investigate their effects on male fertility, meiosis, and the viability and fertility of resulting progeny.

Main Methods:

• Induction of translocations in mouse spermatozoa via X-irradiation.
• Analysis of male heterozygote spermatogenesis and testis mass.
• Examination of meiotic configurations (MI) in oocytes.
• Assessment of progeny genotypes (XO, tertiary trisomics) and their viability/fertility.
• Genetic mapping of translocation breakpoints and linked loci.

Main Results:

• Male heterozygotes for both translocations were aspermic, with spermatogenic arrest at pachytene.
• Meiosis in oocytes showed predominant chain quadrivalents, leading to XO and tertiary trisomic offspring.
• Tertiary trisomics were lethal in T37H but sub-viable in T38H, with some fertile XX11 and XXX11 females.
• Exencephaly was observed in T38H trisomics, likely due to distal duplication on chromosome 11.
• T37H/+ females exhibited reduced body weight, and variegation for the 'b' locus was observed.

Conclusions:

• Reciprocal translocations T(X;4)37H and T(X;11)38H induce male sterility and complex aneuploidies in offspring.
• The breakpoints and resulting chromosomal imbalances have differential effects on viability and fertility.
• These translocations serve as valuable tools for genetic mapping and studying chromosome behavior during meiosis.