[Zbrafish] delay in development or high mortality

William Mebane via zbrafish%40net.bio.net (by wmebane from mbl.edu)
Fri Jun 5 15:59:27 EST 2009

I think what you may be experiencing is "suspension" in development possibly due to exposure to low oxygen levels in the rearing dishes (easy to occur esp. if the dishes are covered and the room is warm). Keep the surface area to depth ratio high in your dishes. Developing embryos  will actually rotate w/in the egg towards areas of higher O2 when an egg is partially imbedded in gel! Personally I have not seem this but folks here who are working with micro DO probes have. 

This "suspended animation" quirk happens w/many fish species, perhaps as a method of "holding on" until environmental conditions improve.
I'm preaching to the choir w/this next statement, but making new cells is an extremely aerobic process. No oxygen...things slow down...then die.
Good paper on this by Christopher Ton and colleagues "Physiological Genomics" 13:97-106, 2003

good luck!

----- Original Message -----
From: Marie Winandy 
To: zbrafish from magpie.bio.indiana.edu
Sent: Fri, 5 Jun 2009 10:37:03 -0400 (EDT)
Subject: [Zbrafish] delay in development or high mortality

Hi all, 

since a few weeks, some PhD students in our lab have got problems with
their wild type, non injected embyos: 

- some have a delay in development (14 somites instead of 24); 

- in some dishes, there are 3 or more different developmental stages at
24hpf (while the eggs were collected at the same time, with a 15
minutes interval between each clutch); 

- some clutches show >50 % mortality at 24hpf. 

We also have some pairs laying only dead eggs. 

This occurs in 25-30% of the clutches. At this time, the transgenics
eggs don't seem to be affected. It seems that this occurs more
frequently with eggs collected in the
afternoon. The parent fish are 9-12 months old. Recently, there has
been some NH4+/NH3 and NO2 in the system, but now it's decreased.

We pay attention to let only 50 eggs in the 8cm petri dishes, change
water at least once a day, discard unfertilised eggs at 4hpf. 

Have you any idea of the possible cause(s) of this? Do you think that
the N ions could have influenced individuals at different levels,
making some of them produce good eggs and other no? 

Thank you in advance for any shared idea and help. 

best regards, 


William N. Mebane
Superintendent Aquaculture Engineering Divison
Marine Resources Center, Marine Biological Laboratory
7 MBL Street Woods Hole, MA 02543
phone (508) 289-7683 fax (508) 289-7900
MBL website - www.mbl.edu
Haiti website http://www.mbl.edu/mrc/outreach/sustainable_aquaculture/index.html
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