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First published online June 29, 2007
Journal of Experimental Biology 210, 2430-2435 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.003541
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Intermittent hypoxia in eggs of Ambystoma maculatum: embryonic development and egg capsule conductance

J. Hunter Valls and Nathan E. Mills*

Department of Biology, Harding University, Searcy, AR 72149, USA


Figure 1
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  		Fig. 1. Diurnal PO2 fluctuation profiles for each treatment immediately before and after the experimental period. Curves are based on hourly measurements taken during periods of PO2 fluctuation 3 days prior to and immediately following the experiment. Values are means ± s.d. (N=6).

 

Figure 2
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  		Fig. 2. Daily developmental differences among treatments. Lines terminate on the day the first embryo hatched in each treatment. Values are means ± s.e.m.; N=50. Reference lines at stages 32 and 38 facilitate recognition of the divergence of developmental trajectories among treatments. At stage 32, embryos in the 18.8 kPa treatment were approximately 1 day in development ahead of embryos in the 1.8 kPa treatment, whereas at stage 38 this difference had increased to 4 days.

 

Figure 3
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  		Fig. 3. Effect of minimum PO2 on days to stage 39 (A), days to hatching (B), and stage at hatching (C). Values are means ± s.e.m., N=50. Lower nightly PO2 caused slowed development (A), delayed hatching (B), and developmentally premature hatching (C).

 

Figure 4
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  		Fig. 4. Effect of minimum PO2 on increase in egg capsule inner radius (ri). Filled circles, mean proportional increase from the beginning of the experiment to day 8; open circles, mean increase from the beginning of the experiment to stage 39. Values are means ± s.e.m.; N=50. The degree of increase in ri was not significantly different among PO2 treatments.

 




© The Company of Biologists Ltd 2007