Biology Reference
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female
Carassius auratus,
Zhang et al. (2009) have characterized global
gene expression patterns as a function of the spawning cycle. A core
set of 873 genes in hypothalamus are differentially expressed during
the periods of pre-spawning (May), post-spawning (i.e., gonadal
regression season in October) and in early gonadal redevelopment
(December). Changes in expression pattern of these genes (including
isotocin, ependymin II, GABA
A
γ2 receptor, calmodulin
and
aromatase b
) are
shared by telencephalon. These genes are regulated by photoperiod.
The hormones and their genes functionally involved with G-protein
coupled receptor, signaling the shift from gonadal regression to the
pre-spawning stage.
(iii) Anti-Mullerian hormone (
amh
), also known as Mullerian duct
inhibiting substance (
MIS
), is a glycoprotein hormone gene of
the super family of β-transforming growth factors. Teleost fi shes
do not have the Mullerian duct. Yoshinaga et al. (2004) have
demonstrated for the fi rst time the dimorphic expression of
amh
mRNA in
P. olivaceus.
The clone of
amh
of the fl ounder spans to
291 bp in length and the deduced amino acid sequence shows
high identity to those of mammals and birds.
amh
mRNA has been
detected in Sertoli cells surrounding spermatogonia but not in those
surrounding spermatocytes and spermatozoa in the testis at 30 dph.
It is also not detected in the ovary of the genetic and sex reversed
phenotypic females. In the eel, a substance similar to
amh
labeled
eSrS21
is identifi ed in Sertoli cells of immature testicles (Miura et
al., 2002). Hence the regulation of spermatogonial proliferation and
differentiation may be one of the common functions of
amh
in fi sh
and amniote vertebrates, which possess the Mullerian ducts. There
are also evidences for the role of
amh
in germ cell proliferation in
O.
latipes
, being stimulatory during early embryonic stage but inhibitory
at the onset of puberty (Shiraishi et al., 2008). In mammals,
amh
is
glycosylated in the N terminal part of the protein region, which
enhances the activity of the C terminal fragment. The C terminal
fragment contains the conserved TGFβ domain. Antibodies raised
against
amh
N and C terminal part of
amh
have been used to study
the processing of endogenous and recombined
amh
of zebrafi sh.
amh
is processed to become bioactive and has independent functions in
inhibiting both steroidgenesis and spermatogenesis.
(iv) Wilm's tumor suppressor gene (Wt1): Two
Wt1
genes have been
identifi ed in zebrafi sh (Perner et al., 2007) and medaka (Kluver et al.,
2009). In medaka, it is concomitantly expressed in the somatic cells
of gonadal primordium.
(v)
Sf-1,
the homologue of
Sf-1
of mammals, has been identifi ed in medaka
(Watanabe et al., 1999), salmon (Higa et al., 2000) and zebrafi sh (von
