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Fig. 7. Abnormalities of basonuclin-RNAi transgenic embryos. Fertilized eggs
were examined under DIC (Normaski) optics (A-D) or fluorescence (DAPI)
(E-G). (H-L) Merged images. Compared with non-transgenic
one-cell embryos (A), the transgenic T50 embryos had a much rougher cell
surface (B-D) caused by numerous `bumps' (B-D,L, black arrowheads). At the
same one-cell stage, the transgenic pronuclei, as revealed by DAPI staining,
were smaller (F-H) and contained irregular DNA distribution (white arrow in F)
when compared with the control (E). In some transgenic embryos, additional
nucleus/chromatin aggregates were seen (white arrowhead in G,H), some of which
were probably derived from polyspermy (arrow indicates the head of an attached
sperm). At the two-cell stage and beyond, additional abnormalities were seen
in transgenic embryos but not in control (I); some examples were collapsed
embryos with disorganized chromosomes (J), incomplete chromosome segregation
during mitosis (K, arrowhead indicates the two chromatin mass was still linked
by a thread of DNA) and cytoplasmic fragmentation (L, white arrow). (M)
A summary of the defects of transgenic T50 embryos during the early
pre-implantation development in culture. The observed defects were indicated
above the time line (thick black line) of one-cell to two-cell embryonic
development (Moore et al.,
1996). The cell-cycle stages (G1, S, G2 and M) were shown above
the time line and the hours post copulation (hpc) below. The black dots
indicate that the timing of the observation could be determined to a
particular stage of the cell cycle; the short thick lines imply that the
measurements were made on pooled one- or two-cell embryos at varying stages of
the cell cycle. The autoradiogram of a PAGE gel shows the presence of TRC in
both the control and transgenic embryos. Scale bars: 50 µm in C; 10 µm
in E,I.
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