Biology Reference
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Fig. 2.6 Proteasomes and fertilization. a, a
0
Zygote obtained after in vitro fertilization of bovine
oocytes in control conditions. a Proteasomes (green fluorescence) are concentrated on both
pronuclei. a
0
Complete development of sperm aster (tubulin red fluorescence) and fully apposed
pronuclei (blue fluorescence). b Bovine oocyte after IVF in the presence of E446 anti proteasome
antibodies delivered by the Chariot reagent (Rawe et al.
2008
). An intense labeling of
proteasomes (green fluorescence) is seen on the cytoplasm of the zygote and concentrated on the
sperm connecting piece (arrow, boxed area). B
0
: Detail at higher magnification. Strong
proteasome concentration (green fluorescence) covers the connecting piece close to sperm
nucleus (blue fluorescence). b
00
Same area as b
0
. Failure of microtubule polymerization and sperm
aster formation (tubulin red fluorescence). The sperm connecting piece and flagellum are clearly
seen and the nucleus (blue fluorescence) has not decondensed. Bars represent 20 lm(a, a
0
, b) and
5 lm(b
0
, b
00
) (Figure
2.6
was originally produced by Rawe et al. (
2008
) and modified by Chemes
and Rawe (
2010
), and is reproduced with permission from the publishers)
may involve various mechanisms including ubiquitin-mediated proteolysis of selected
targets by 26S proteasomes recently localized near the centrosome in the neck region of
human spermatozoa (Wójcik et al.
2000
;Raweetal.
2008
). A reduction below 20 and
40 %
of
control
values
was
found
in
the
activities
of
proteasome
enzymes
