Antifertility test on rats and fish

[louise]

Hi,


I wonder if anyone here could gave me some advice on this subject.

Most of the researches and test are usually conducted on rats and possibly some freshwater fishes(aquaculture purposes/prevent cross breeding) when they are sexually matured.

I would like to know if these chemical was administered to
the animals prior to reaching sexual maturity,say from juvenile stage,
would it be just as effective in attaining permanent infertility?

Thanx for your time.

Louise L

[InfiniteNow]

Can you clarify or elaborate on your question a bit?

You mention the concept of antifertility tests, but no specific tests or test results.

You mention chemicals which were administered, but nothing specific.

Also, have you tried to search these concepts on your own? If so, did you hit an obstacle that you are having difficulty overcoming?

Give us some more information and what you've done already so we can try to help you.

[louise]

InfiniteNow,

thank you for your prompt response.
I'm really sorry for not making myself clear.

I have been searching for antifertility techniques on the internet
to assess and determine which one could be applied with reasonable
amount of success to freshwater fish,in particular ornamental fish to prevent cross breeding.

I could not find specific info on ornamental fish but was drawn to this particular research that uses pawpaw/papaya seed as an antifertility control on tilapia aquaculture.The chemical properties of pawpaw seeds also proved effective on rats.However, most of the test used specimens which had attained sexual maturity.I would like know if pawpaw seeds ,applied at appropriate dosage,would result in permanent infertility
in juveniles as well where their sexual organ are not fully developed.

I'm sorry I could not post the link to the research report yet but if you would like to have some first hand knowledge here,the title is , "Pawpaw seed as fertility control agent on male Nile tilapia".


I also would like to know if their are any yardstick I could use when determining the appropriate dosage for different species of fishes such as american cichlid,goldfish,live bearers etc.

Thank you for your kind attention.

Louise L

[InfiniteNow]

Great. Thanks for the info. I can now tell a bit more about what you seek, and also that you have already begun to engage in the process yourself. You also demonstrate an articulate understanding, and hopefully more members here will be able to contribute to the success of finding good answers to your question.

One possible approach is to determine what INCREASES fertility in fish, and then try eliminating that chemical somehow. The following study speaks a bit to that issue:

http://jeb.biologists.org/cgi/conten...ct/200/22/2833


Some other cool information, while it may not be directly related to your approach, will hopefully stimulate some new ideas:

http://www.pnas.org/cgi/reprint/36/9/464
[.pdf warning]

Experiments reported in the paper referred to above indicated
that the male of L. reticulatus may ifideed exhibit a remarkably high degree
of selectivity for conspecific females in mixed populations which have been
in equilibrium for some time. No evidence was found in any of these
observations, however, that the females of any of the three species exhibit
a similar selective response to the appropriate males. Thus the predominant,
if not the whole, share of sexual selection appears initially to reside
with the male.

Based on the above, another approach might be to change the appearance of the skin/scales, or engage in some melatonin therapy or bleaching process, as perhaps it is selection (mate choice) itself causing the issue. Now, with ornamental fish, this might not be your best approach, but again, hopefully some new ideas.

http://www3.interscience.wiley.com/c...TRY=1&SRETRY=0

The condensation of chromatin in spermatids occurred, but the diameters of sperm heads were about 1.5-fold larger than those of normal ones. Prominent abnormalities were apparent in the quantity and arrangement of microtubules in the cytoplasm. Abnormal spermatozoa were phagocytized by Sertoli cells. These observations indicate that the mechanisms of impaired gametogenesis in these interspecific hybrids are sexually differentiated.

Cheers.