Chromosome aberrations and spermatogenic disorders in mice with Robertsonian translocation (11; 13)

Abstract

Objective: To determine the diagnostic features of Robertsonian (Rob) translocation (11; 13) in mice and the mechanisms underlying the effect on spermatogenesis and reproductive decline.

Methods: A Rob translocation (11; 13) mouse model was established by cross-breeding, and confirmed by chromosome analysis. Chromosome aberrations and translocation patterns were identified in mice with Rob translocation (11; 13) by fluorescence in situ hybridization (FISH). Spermatogenic disorders were investigated at different stages of spermatogenesis. Immunofluorescent analysis was performed on sections of testis and epididymis specimens during spermatogenic meiosis. The weight of the testes and reproductive decline were recorded.

Results: The crossed Rob translocation (11; 13) mouse has 39 chromosomes, including a fusion chromosome (included chromosomes 11 and 13) using dual color FISH. There was no difference in the distribution pattern of SYCP3 and γH2AX in spermatocytes between Rob translocation and wild-type mice; however, round haploid spermatids presented characteristic morphologic changes of apoptosis and the number of haploid spermatids was decreased. Furthermore, the immature germ cells were released into the epididymis and the number of mature sperm was reduced.

Conclusions: Chromosome aberrations and spermatogenic disorders may result from apoptosis of round haploid spermatids and a reduced number of mature sperm in Rob translocation (11; 13) mice. Abnormal sperm and reduced number of sperm may be one of the main reasons for reproductive decline and male infertility in Rob translocation (11; 13) mice.

Keywords: Infertility; Robertsonian translocation; mouse; spermatogenesis.

Figure 1

Metaphase chromosome spreads from F1 Rob translocation mouse lymphocytes and FISH. A. Metaphase chromosome spreads from F1 Rob translocation mice, including a fusion chromosome; B. Hybridization signals on the Rob translocation fusion chromosome (orange and green) obtained with dual color labeled probes. Images were captured with laser confocal microscopy. The scale bars represent 10 μm for all images.

Figure 2

Rob translocation mouse testis sections were detected by immunostaining. A. SYCP3 (green) was used as a marker for identifying germ cells at different stages of prophase of the first division of meiosis. B. γ-H2AX was stained green. DNA was revealed by the blue DAPI staining. Low magnification and high magnification images. Images were captured with laser confocal microscopy. The scale bars represent 100 μm.

Figure 3

Rob translocation mouse and wild-type mouse epididymis sections were detected by immunostaining (DAPI stain). A. 4 W of F1 Rob translocation mouse epididymis sections; B. Adult F1 Rob translocation mouse epididymis sections; C. Adult wild-type mouse epididymis sections; DNA was revealed by blue DAPI staining. Low magnification and high magnification images. Images were captured with laser confocal microscopy. The scale bars represent 100 μm.

Figure 4

Weight of adult F1 Rob translocation mouse and wild-type mouse testis.