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FIG. 4. Bcl-xL protein is concentrated in the METRO (germ plasm)
region of the mitochondrial cloud of Xenopus oocytes. (A) Whole
mount and (B) section of oocyte hybridized in situ with digoxigenin
labeled antisense Xcat2 RNA probe. Xcat2 mRNA is localized in the
germinal granules, which are restricted to the METRO region of
the mitochondrial cloud (arrows). (A) Top view of the oocyte showing
the ring of labeled germinal granules at the apex of the mitochondrial
cloud (arrow). The center of the mitochondrial cloud is devoid
of germinal granules and remains unlabeled. (C) Bcl-xL protein is, as
is Xcat2 mRNA, distributed in the mitochondrial cloud in the ringlike
pattern (arrow). (D) Electron microscopy image of two independent
fragments of the mitochondrial cloud with the METRO region;
i.e., the peripheral ring of germinal granules (marked with red stars)
between mitochondria. (E, F) Electron microscopy image of the
fragment of the METRO region of the mitochondrial cloud with the
germinal granules (short arrows) visible between the mitochondria
(long arrows) from (E) control and (F) heat-shocked Stage I oocytes.
Mitochondria and germinal granules in the heat-shocked oocyte
show abnormal ultrastructure. Mitochondria are swollen and devoid
of cristae, and the germinal granules are swollen and less homogeneous
than those in controls. N, nucleus. Scale bars represent 50
lm in panels A–C and 4 lm in D. |
