[Zbrafish] Unfertilized egg

christian lawrence clawrence at rics.bwh.harvard.edu
Wed Sep 27 11:45:41 EST 2006

What you describe suggests to me that your environment is less than
favorable for regular egg production.  Wherever the fish came from, they
were clearly in an environment conducive to rapid cycling of females.  The
"environment" incorporates various things like water chemistry, diet, and
the social situation the fish are held in.

For example, when fish arrive from farms, they are often readily strippable,
presumably because they are fed high quality live feeds on a frequent basis,
and also because the stocks are PROBABLY genetically diverse and from very
large populations (greatly in excess of what you see in a typical biomedical
research facility).

When you bring them into your facility, even if your water quality and your
diet is excellent, the population (and therefore some proportion of the
genetic diversity) has been reduced.  Further, they probably will be getting
less feed than they receive at farms.    If your diet and/or water quality
is subpar on top of this, well, then you get the picture.  

When the conditions promoting rapid cycling are gone, and so then goes the
rapid cycling.

You've got to do your best to restore those conditions.

Females from laboratory populations, if they are regularly exposed to
unrelated males and fed a high quality diet under a favorable and consistent
water quality regime, will ovulate once every few days.    This doesn't mean
that they will be strippable , although they should be.  Feed them live feed
(Artemia) 3-5 times a day and if possible co-feed 1x daily a dry diet with
elevated levels of PUFA/HUFAs and vitamin C.   Keep them with males, but
lower numbers (2-3:1 F:M ratio), set them up in mock crosses (or at least
have them with males until the night before you strip) and then strip them.
Try once a week.

Let me state quite plainly that the above is a crude approach, based on what
little is actual known about the regulation of the ovulatory cycle in
zebrafish.   This is an area of research that needs work, especially if IVF
is going to be part of your regular routine and you don't want to accept 50%
squeeze rates from females squeezed once every 2-3 weeks.

Good luck


Christian Lawrence
Brigham and Women's Hospital
Karp Family Research Laboratories 06-004B
One Blackfan Circle
Boston, Massachusetts 02115
Tel: 617.355.9041
Fax: 617.355.9064

-----Original Message-----
From: zbrafish-bounces at oat.bio.indiana.edu
[mailto:zbrafish-bounces at oat.bio.indiana.edu] On Behalf Of jenny
Sent: Wednesday, September 27, 2006 9:38 AM
To: bionet-organisms-zebrafish at moderators.isc.org
Subject: [Zbrafish] Unfertilized egg

  hello!everyone,I'm doing some IVF experiments about zebra fish, so I need
many mature unfertilized eggs by stripping the female, my problem is that:
  when I bought a new batch fish, the females are easy to be stripped some
egg,after sevaral days, the female cann't produce egg any more though we do
our best to feed them good food,eg.artemia and some powder.It seems that the
longer fish was raised,the least chance we will get the egg.so I have no
choice but to buy a new batch fish once IVF test.It cost me lot of time and
energy.So how to deal with this problem?
   Looking forward to your reply!thanks!

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