Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Red-eyed treefrog embryos actively avoid asphyxiation inside their eggs

04.11.2008
Boston University undergraduate Jessica Rogge and associate professor Karen Warkentin, working at the Smithsonian Tropical Research Institute's laboratories in Gamboa, Panama, discovered that frog embryos at a very early developmental stage actively respond to oxygen levels in the egg—as reported in the Nov. 7, 2008 issue of the Journal of Experimental Biology. These initial responses to the environment may be critical to the frogs' long-term survival.

Red-eyed treefrogs, Agalychnis callidryas, lay jelly-covered egg clutches on leaves overhanging tropical ponds. Each clutch of several dozen transparent eggs is ready to hatch after only four days.

By delaying hatching by a few more days, frog embryos significantly increase their chances of survival as tadpoles in the pond below where predators lurk. But as each egg matures, and embryos need more oxygen, less and less of the vital substance is available inside.

Warkentin has measured oxygen levels as low as 2% air saturated in the middle of red-eyed treefrog eggs—yet the embryos refrain from hatching. "You'd think they would be dead. You'd think they would hatch. But they continue to develop at the same rate as embryos in eggs with much, much more oxygen," she explains. "Jessica found that these embryos maintain high metabolic rates and rapid, synchronous development by behaviorally positioning their external gills in a small high-oxygen area, a sweet spot near the exposed surface."

The team used a video camera to record embryo movement in the egg. By gently manipulating the eggs with a probe, Rogge turned the embryos within the eggs so that the gills were positioned away from the surface, in lower oxygen. "It's a lot like trying to pick something up out of a glass of water with your fingers," says Rogge, "the embryo 'wants' to be at the front of the egg, so unless I turned the embryo completely around in one motion it would come back to the front before I could finish spinning it."

Rogge found that even very young, neural-tube-stage embryos, before developing gills, blood, or the ability for muscular movement, kept their developing head in the oxygen sweet spot. "Once we started with the behavior research, it sort of snowballed and we suddenly got to the point where I spun the one-day-old embryos. We figured they would turn back, because they had ciliary rotation, but watching them ever so slowly return to the front, almost like clock-work, was amazing."

Rogge also induced embryos to lose their gills in the egg -- and was thus able to directly measure and compare the oxygen uptake ability of animals with and without gills, in eggs and in the water. "Embryos normally keep their external gills as long as they stay in the egg, but when they hatch they re-route the blood flow and the gills shrivel up in a matter of minutes" said Warkentin. "Now this makes sense. The external gills aren't much use to tadpoles, but they seem to be critical for embryos if they are to get enough oxygen."

People don't typically think of eggs as "doing" much. However, early development is a crucial time when death is a common occurance, and natural selection will favor any ability the embryo may have that increases its chances of survival.

Beth King | EurekAlert!
Further information:
http://www.si.edu

More articles from Life Sciences:

nachricht Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>