Saturday, June 11, 2011

Male… oops female.. or lemme say, “Sex changing Toads (Amphibians)”


Do you Remember Jurassic park? How the All male Dinosaurs became able to reproduce? According to the movie, the Scientists used Amphibian DNA(of Frog or something) while ‘re-Producing’ New dinosaurs, And according to ‘all famous’ Darwin’s law of struggle for existence, the male converted themselves to female so that they could reproduce and continue the race. Was that that easy? A male converting itself to female isn’t that simple to occur itself is it? There are many Hermaphrodites which can act both as male and female but changing sex doesn’t mean being an hermaphrodite, its converting a male into female.

In fact its not just the movie, Sex change is common in many amphibians, commonly in toads. Even the toughest of known toads, the cane toad, Bufo marinus, which is famed for indestructibility has found to be prone to sex change. According to American scientists, the male toads in intensively farmed land are changing sex. This is probably  why the world’s amphibians are disappearing.

The Florida scientists have found that the changes are likely to be "the result of multiple exposure to several chemicals at various concentrations over the lifetime of the toads". Previous, disputed, studies have suggested that some pesticides may have this effect on amphibians, while research at Yale University found that male green frogs were being feminised much more often in suburban gardens than on farmland. Whatever the cause, the phenomenon may explain why amphibians are now the most endangered class of animal on the planet. More than 120 species are believed to have become extinct, and almost a third of those that are left are in danger.

Atrazine, on of the most commonly used weed killers, can turn male frog into females, researchers have found.

"Atrazine-exposed males were both demasculinised (chemically castrated) and completely feminised as adults," researchers from the University of California Berkeley wrote in the Proceedings of the National Academy of Sciences.

The chemical had been shown to disrupt development and make frogs develop both male and female features - termed hermaphroditism.

Tyrone Hayes from the University of California Berkeley says the study of 40 male frogs shows the process can go even further.

"Before, we knew we got fewer males than we should have, and we got hermaphrodites. Now, we have clearly shown that many of these animals are sex-reversed males," Mr Hayes said in a statement.

"Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution."

Is the similar effect seen in Human?

Well the amphibians have thinner skin so that they can absorb atrazine pretty easily, whereas its not so in case of human. However sex change is also possible in case of human. its just the manipulation of hormones that is necessary, although there are many moral, legal and ethical complications.

Just for note: Developing embryos (irrespective of the sex) contains both ‘Mullerian’ and ‘Wollfian’ ducts which develop into female and male reproductive system respectively if appropriate condition/ hormonal balance is achieved to grow into respective sex. of course both male and female contains estrogen and progesterone in less or more quantity, which affects the sexual expression.

note: Its just a blog post, if you are interested in knowing more about this thing, please refer more reliable scientific journals and papers.


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