Figure 3

HVJ-E Sendai extract fusion of mouse round spermatids into GFP CETN2-expressing mouse oocytes demonstrates paternal TACC3 LISD organization at the incorporated paternal centrioles but sparse paternal microtubule assembly. (A–C) Prometaphase-I oocyte (A): DNA, F Chr; blue) 2-h post Sendai-extract fusion with a round spermatid (A: DNA, blue). TACC3 LISD condensates (B, C: blue) congress around and bind the assembling female meiotic spindle microtubules (A, C: red) harboring a single spindle pole GFP CETN2 expressing foci (A–C: green, arrow). The incorporated GFP CETN2-expressing male spermatid centrioles (A–C; green, arrowheads) also have TACCs LISD condensates engulfing them (B, C: blue, arrowheads) but without microtubule assembly (A, C: red). (A) Upper inset: a pre-fusion round spermatid (blue, DNA) expressing GFP CETN2 (green) but no TACC3 (blue). (A) lower inset: DIC image confirming spermatid:oocyte fusion (arrowhead). (B, C) upper insets; details, female TACC3 LISD condensates (B) and microtubule organization (C) at the GFP CETN2-expressing foci (B, C: green, arrow). (B, C) Lower insets: details, paternal TACC3 LISD condensates (B, blue, arrowhead) with no microtubules (C, red, arrowhead) at the incorporated paternal centrioles (B, C: green). (D–F) GFP CETN2-expressing spermatocyte (D: lower inset, arrowhead; DIC): GFP CETN2-expressing mouse GV oocyte dyad 4-h post-fusion. The female bivalents condense (A–C: F Chr; blue) as spindle microtubules assemble (D, F: red) with a single GFP CETN2-expressing maternal centriole foci (D–F: green, arrows) at one pole. Expansive TACC3 LISD condensates assembles around the developing spindle (E, F: blue). The incorporated spermatid expresses GFP CETN2 centrioles (D–F: green, arrowheads) near the male decondensing sperm chromatin (D: Sp Nu, blue) but shows sparse microtubule assembly (D, F: red). Extensive TACC3 LISD condensates (E, F: blue) surround and bind the poorly organized spindle microtubules at the paternal DNA (E and F insets: details, TACC3 (blue), microtubules (F: red), and GFP CETN2-expressing foci (E, F: green) at female (F) and male spindle poles. All images: GFP CETN2-expressing oocytes:spermatid fusions immunolabeled for microtubules (red; A, C, D, F), TACC3 (blue: B, C, E, F) and DNA (A, D: blue). F Chr, female chromosomes; Sp Nu, sperm nucleus; F, female. Scale bars = 10 µm.