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![](3D"slide0001_image002.jpg")
![](3D"slide0001_image004.jpg")
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Lansopraz=
ole
Exposure from Stages 2 and 6 to 16 of Xenopus laevis =
Embryos Inverts Direction of
Intestinal Coiling
Adam Secrest and Maureen Keog=
h, Davidson College, Davidson, NC
Introduction:
. =
Expression of the growth/develop=
ment
factor Nodal
induces a casca=
de
effect, which ultimately produces asymmetry in visceral organs: heart, gallbladder and
intestinal coiling. An event upstream of Nodal regulates its expression.1
. <= span style=3D'font-family:Arial;font-size:42%'>Left-right asymmetry determinati= on depends on early activity of H+/K+ ATPase. Lansoprazole acts as an H+/K+ ATPase transporter blocker.=
2
. A previous study by Levin et al. demonstrated 51% of Xenopus laevis embryos treated with lansoprazole induced heterotaxia in the form of inverted heart, gallbladder and intestinal coiling. Levin et al. proposes that H+/K+ ATPase transporter acts as the upstream regulator of Nodal. 2
. <= span style=3D'font-family:Arial;font-size:42%'>Left-right asymmetry determinati= on depends on early activity of H+/K+
. A previous study by Levin et al. demonstrated 51% of Xenopus laevis embryos treated with lansoprazole induced heterotaxia in the form of inverted heart, gallbladder and intestinal coiling. Levin et al. proposes that H+/K+ ATPase transporter acts as the upstream regulator of Nodal. 2
What effect do stage 46 Xenopus laevis embryos show when treated with lansoprazole following <=
/b>fertilization through stage 1=
6?
References:
1 Wall
et al. (2000). G=
ene.
Dev. Bio. 227: 495-509.
2Levin et al. (2002). Cell. 111: 77-89.
2Levin et al. (2002). Cell. 111: 77-89.
Methods:
. Xenopus eggs fertilized and cysteine-tr=
eated
directly =
prior
to treatments. Approximately=
25
embryos were subjects in one of four conditions: 20% Steinberg’s <=
/span>(control), .054% MeOH, 27=
µM
lansoprazole, or 54 µM
lansoprazole=
.
. Developing embryos were treated at two different stages, 2 and 6, and remained ex= posed until stage 16. At stage = 16, embryos were removed and washed three times with 20% Steinberg’s solution.
. Embryos were reared until stages 4= 5-47 in 20% Steinberg’s solution at which point they were fixed with gluteraldehyde and scored f= or direction of intestinal coiling.
. Developing embryos were treated at two different stages, 2 and 6, and remained ex= posed until stage 16. At stage = 16, embryos were removed and washed three times with 20% Steinberg’s solution.
. Embryos were reared until stages 4= 5-47 in 20% Steinberg’s solution at which point they were fixed with gluteraldehyde and scored f= or direction of intestinal coiling.
Results:
![](3D"slide0001_image012.jpg")
Stage 46 tadpoles representing
various intestinal coiling morphologies observed.
Top left and right. Tadpole with wild type intestinal coiling in a clockwise direction. Top right picture is the same tadpole at a higher magnification showing direction of intestinal coiling in more detail.
Middle left and right.= Heterotaxic tadpole with <= /span>inverted intestinal coiling in a counterclockwise direction. Mi= ddle right picture is the same tadpole at a higher magnification showing direction of intestina= l coiling in more detail.
Bottom left. Edemic tadpole with swollen gut a= rea and underdeveloped intestines.
Bottom
right. Tadpole with intestines outside o=
f body.
Top left and right. Tadpole with wild type intestinal coiling in a clockwise direction. Top right picture is the same tadpole at a higher magnification showing direction of intestinal coiling in more detail.
Middle left and right.= Heterotaxic tadpole with <= /span>inverted intestinal coiling in a counterclockwise direction. Mi= ddle right picture is the same tadpole at a higher magnification showing direction of intestina= l coiling in more detail.
Bottom left. Edemic tadpole with swollen gut a= rea and underdeveloped intestines.
Percentage of heterotaxic tad=
poles observed in each condition.
Percentage of heterotaxic tadpoles is directly related to <=
span
style=3D'position:absolute;top:44.57%;left:70.21%;width:26.53%;height:2.16=
%'>lansoprazole concentration. In both lansoprazole exposure lengths, f=
rom
stage 2 to 16
and 6 to 16, the percentage increased over the Steinberg’s control an=
d MeOH
control. The <=
span
style=3D'position:absolute;top:52.53%;left:70.21%;width:29.06%;height:2.16=
%'>percentage of heterotaxic tadpol=
es
from the trial
exposed at stage 6 was slightly higher than those exposed at stage 2 in both=
concentrations of lansoprazole.<=
/span>
Summary and Conclusions:<=
/span>
.<=
span
style=3D'mso-spacerun:yes'> Lansoprazole blocks the H+/K+ ATPase transporter and increases the
percentage of
heterotaxic tadpoles.
. Stage of initial exposure did not appear to have a discernable affect on = percentage of heterotaxic tadpoles.
. Stage of initial exposure did not appear to have a discernable affect on = percentage of heterotaxic tadpoles.
Ø <=
/span>Our results agree with
Levin’s results and thus supports his hypothesis that the H+/K+ ATPa=
se transporter is the upstream
regulator of Nodal.
.<=
/b> Pictures were taken with a digital camera and =
Photoshop. Data was analyzed and graphs produced with Excel.