Biology Reference
In-Depth Information
Fig. 4.
Ontogenetic pathways of sex differentiation in selected hermaphrodites. Simultaneous
hermaphrodites: A =
Kryptolebias marmoratus,
B =
Serranus baldwini,
Monoandrics: C =
Cromileptes altivelis,
D =
Tigrigobius multifasciatum,
Diandrics : E =
Parapercis snyderi,
F =
Suezichthys gracilis,
G =
Pagrus pagrus
, Protandric : H =
Diplodus vulgaris.
XX = Somatic egg,
O = Egg, OT = Ovotestis, OL = Ovarian luman, H = Hatching, P = Puberty, M = Maturation,
S = Senescence? p♂ = Primary male, s♂ = Secondary male, XO = Male from sex changed
hermaphrodite
sources is synthesized. These publications elucidate the process of Genetic
Sex Differentiation in Fish employing sophisticated modern techniques
capable of very precise analyses. Incidentally, 50-52% of the references cited
are dated after 1995 in the fi rst two topics but more than 77% are dated after
2000 in this topic. Hence the publications on sexuality, sex determination
and differentiation in fi shes have projected the research into a 'hot area'
and are being covered by increasing numbers and kinds of journals; for
instance, from the Journal of Morphology and Animal Behaviour to Cell,
and Chromosome Research, and to Genes and Genomes. Secondly, the
area of research has also moved from observational to experimental and to
analytical during the last decade. Besides, the fact that the citations of more
than 77% of references in this topic are dated after 2000, clearly indicates
that this area of research is not only 'hot' but also 'explosive'.
A reason for the explosive number of publications in this 'hot' area may be
traced to the availability of new techniques and tools. Table 6 briefl y explains
some of these techniques as an introduction to graduate students. The
in situ
hybridization
technique, fi rst described in 1969, bloomed into FISH in 1990.
Nanda et al. (2000) are perhaps the fi rst to use FISH with BACs as a probe to
detect sex chromosomes in
Xiphophorus maculatus.
Immuno-histochemical
staining has been widely used in this area of research; for instance, adaptive
