Analysis of Meiosis in SUN1 Deficient Mice Reveals a Distinct Role of SUN2 in Mammalian Meiotic LINC Complex Formation and Function
Figure 1
Presence of meiotic telomere attachment in Sun1−/− mouse strains.
(A) Telomere fluorescence in-situ hybridization (TeloFISH) in co-localization with Lamin B and SYCP3 immunofluorescence on representative 15 dpp (days past partum) Sun1+/+(Δex10-11) and littermate Sun1−/−(Δex10-11) testis sections (A, A′) and 17.5 dpf (days past fertilization) Sun1+/+(Δex10-11) and littermate Sun1−/−(Δex10-11) ovary sections (A″, A′″). In all WT sections investigated, attached telomeres appear embedded within the labeled lamina (white arrowheads in A and A″). All sections from knockout tissues clearly show both detached, internal telomere signals (yellow arrows in A′ and A′″) as well as attached, peripheral telomere signals (white arrowheads in A′ and A′″) in both oocytes and spermatocytes. Peripheral, attached telomeres in SUN1 deficient oocytes and spermatocytes are also seen at the ends of synaptonemal complex (SC) axes shown by SYCP3, as is the case in wildtype cells. Scale bar 10 µm. (B) Representative electron micrographs of spermatocytes from adult Sun1+/+(Δex10-13) (B) and Sun1−/−(Δex10-13) (B″) [11] mice and of spermatocytes from 15 dpp Sun1+/−(Δex10-11) (B′) and Sun1−/−(Δex10-11) (B′″) [21] mice. (C) Representative electron micrographs from E17.5 female Sun1+/+(Δ10-11) (C–C′) and Sun1−/−(Δ10-11)(C″–C′″) oocytes. In male wildtype meiocytes of both mouse strains and female wildtype meiocytes of the SUN1(Δex10-11) strain, components of the SC and the telomere attachment plates (black arrowheads) are clearly visible. Meiocytes from all Sun1−/− males (B″– B′″) as well as females (C″–C′″) also show the wildtype-like formation of telomere attachment sites. (D) Quantification of attached and non-attached telomeres in wildtype and knockout spermatocytes at different meiotic stages. Pre-leptotene/early leptotene spermatocytes from littermate 12 dpp mice (D), zygotene spermatocytes from littermate 12 dpp mice (D′) and spermatocytes from littermate 14 dpp mice in a pachytene or pachytene-like stage, respectively (D″). (12 dpp pre-leptotene/early leptotene: Sun1+/+(Δex10-11) n = 16 spermatocytes, 772 telomeres; Sun1−/−(Δex10-11) n = 13 spermatocytes, 645 telomeres. 12 dpp zygotene: Sun1+/+(Δex10-11) n = 5 spermatocytes, 194 telomeres; Sun1−/−(Δex10-11) n = 7 spermatocytes, 337 telomeres. 14 dpp pachytene: Sun1+/+(Δex10-1)1 n = 54 spermatocytes, 2138 telomeres; pachytene-like Sun1−/−(Δex10-11) n = 31 spermatocytes, 1150 telomeres.) LE lateral element, CE central element, NE nuclear envelope, Nuc nucleoplasm, Cyt Cytoplasm.