Biology Reference
In-Depth Information
Table 23.
Land mark achievements in germ cell research on fi shes.
Team
Events
Hamaguchi (1982)
PGC migration in medaka
Hong et al. (1996)
ES cell lines from medaka
Olsen et al. (1997)
Yoon et al. (1997)
Vasa
as germ cell marker
Hong et al. (1998)
ES cell-derived chimeras
Yoshizaki et al. (2000)
Transgenic rainbow trout with labelled PGC
Wakamatsu et al. (2001)
ES-derived fertile diploid medaka
Yoshizaki et al. (2002)
Mass isolation of PGCs in rainbow trout
Takeuchi et al. (2003)
Rainbow trout fry by PGC transplantation
Takeuchi et al. (2004)
Xenogenic trout using masu as surrogate
Okutsu et al. (2006)
Allogenic trout by SSCs transplantation
Yoshizaki et al. (2010)
Allogenic trout by OSCs transplantation
Yoshizaki et al. (2010)
Allogenic trout by OSCs transplantation to masu
Incidentally, spermatocysts in the adult testis undergo spermatogenesis
in the presence of 11-KT. But, they choose an alternate pathway and form
Spermatogonial Stem Cells (SSCs) in the presence of estrogen (see Pandian,
2011). It remains to be seen which steroidogenic hormone induces these
PGCs to OSC pathway.
Isolation of germ cells: To isolate the PGCs of the rainbow trout, Yoshizaki et
al. (2010) have constructed a transgenic transcript with the
Gfp
gene driven
by the
vasa
gene regulatory regions. To reduce the contamination by somatic
cells in the partially isolated PGCs, Takeuchi et al. (2003) devised a fl ow
cytometric separation technique to sort out Gfp-positive from Gfp-negative
somatic cells. Even with the molecular marker and fl ow cytometric isolation,
the SSCs concentration could be increased to > 56% in the testicular cell
suspension used for transplantation. To avoid such contamination, Saito et
al. (2008, 2010) and Higaki et al. (2010) have chosen to introduce only one
PGC of pearl danio or danio for transplantation.
Two different procedures have been followed to isolate SSCs from adult
fi shes. Briefl y, Lacerda et al. (2006, 2010), and Majhi et al. (2009) lysed the
testis of Nile tilalpia and pejerrey, respectively; Lacerda et al. labeled the
SSCs by fl uorescent cell linker PKH26 and the SSCs were isolated by percol
gradient separation. On the other hand, Okutsu et al. (2007) and Yoshizaki et
al. (2011) prepared spermatogonial cell suspension of testis from dominant
red or white body colored male rainbow trout carrying
pVasa-Gfp
and the
isolated labeled SSCs were concentrated fl ow cytometrically. To obtain
pure SSCs, Yoshizaki's team employed two ingenious procedures. They
developed (i) molecular markers
rtili, rt-scp3
and
rt-shippo
for spermatogonia,
spermatocytes and spermatids of rainbow trout, respectively and (ii) the
vase-Gfp
sequence present in the fl ow cytometrically (FCM) isolated
Gfp
-
