Molecular mechanism of gender differences in sexual behaviour deciphered

Health News

New Delhi, October 4 (India Science
Wire): Sexual reproduction is central to maintenance and
propagation of all organisms. Besides the sexual organs, male and female of
human and other higher organisms have differences in their central nervous
system
(brain and spinal cord) and consequently show different sexual
behaviour.

How does this occur? Does it happen at
the embryonic stage itself or later? Researchers at the Hyderabad-based Centre
for DNA Fingerprinting and Diagnostics (CDFD) have found
some answers.

Human and other higher organisms have two
major identifying features:  a
well-defined anterior-posterior axis (head to tail axis) of the body; and a highly
complex central nervous system.

Dr. Rohit Joshi with his colleagues in their lab.

The ‘head to tail’ axis of the body is
characterised by divergent non-repetitive regional features seen along the
length of the body such as the ears, eyes, mouth, nose, arms, and legs. A
family of genes called Homeotic genes express serially along the head to tail
axis and give different regional identities to the cells by regulating differential
gene expression.

The central nervous system comprising the
brain and the spinal cord runs along the length of the body and has ‘head
to tail’ axis determined by Homeotic genes. The divergent and non-repetitive
features in central nervous system are in the form of different neuronal cell
types, which carry out different functions like locomotion, feeding and mating.

Among other things, gender-based
differences – sexual organ and behaviour – are critical for successful mating
and propagation of species. For development of the sexual organs and their
functioning, tail end of the body is evolutionarily specialized for sexual
mating across different organisms. However, several aspects such as how sex-specific
differences in central nervous system and consequently sexual behaviour arise are
not yet known.

In their study done in fruit fly Drosophila melanogaster, CDFD researchers
have found that Homeotic gene involved in making the tail end of its body worked
with the DM domain gene in central nervous system to bring about sexual
dimorphism in early developmental stages. DM domain genes are important for
sexual development.

The team found that in female fruit
fly, the interaction resulted in death of a small subset of neural stem cells,
while such a thing did not happen in the male fruit fly. Thus, female did not
have a subpopulation of specialized neurons, while the male had them. This led
to differences in mating behaviour of female and male fruit flies.

Speaking to India Science Wire,
team leader, Dr. Rohit Joshi, said what has been found in fruit fly could be
happening in human and other higher organisms too. “This is the first report
indicating that Homeotic genes and DM-domain genes physically interact and that
Homeotic gene are capable of using sex specific forms of DM-domain gene as
partners in gene regulations. Considering the wide-ranging role of Homeotic
gene and DM-domain gene in development and determination of sexual identity,
their capacity to collaborate with each other could be a common theme for
generating and maintenance of sexual dimorphism in animal development across different
species”.

Besides Dr. Joshi, the study team
included Neha Ghosh, Asif
Bakshi, Risha Khandelwal and Srivatsan Govinda Rajan, who is currently at
Department of Biological Sciences, University of Illinois at Chicago. The team
has published a report on its work in scientific journal Development. The
study was funded by the Wellcome Trust DBT India Alliance Intermediate
Fellowship and the Department of Science and Technology, among others. 

By Sunderarajan Padmanabhan

(India Science Wire)

ताजा समाचार/आलेख

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