Dr. Jan Michels, Christian-Albrechts-Universi
It might sound a bit cramped, but there's an entire world of organisms that can call a drop of water their home. And, up close, they look practically out-of-this-world. Each year, the Nikon Small World competition sets out to collect some of the best microphotography. Take a look at some of this year's most stunning images of creatures that live in water. This photo from Dr. Jan Michels of Christian-Albrechts-Universität zu Kiel in Kiel, Germany shows Temora longicornis, a marine copepod, from its ventral view at 10 times magnification.
SEE MORE PHOTOS: It's a Nikon Small World After All
Frank Fox, Fachhochschule Trier/Nikon Small W
This microphotograph shows the diatom Melosira moniliformis at 320 times its size.
Jonathan Franks, University of Pittsburgh/Nik
This algae biofilm photographed up-close makes what's usually referred to as "pond scum" look like art.
Michael Shribak and Dr. Irina Arkhipova, Mari
This Philodina roseola rotifer was alive and well when this microphotograph was taken.
Dr. Ralf Wagner/Nikon Small World
This microphoto shows a water flea flanked by green algae.
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Charles Krebs Photography/Nikon Small World
Warfare in a water droplet! This microphoto shows a Hydra capturing a water flea at 40-times magnification.
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Dr. John H. Brackenbury, University of Cambri
One of the ultimate human pests -- the mosquito -- begins life as larvae, here shown suspended in a single droplet of water.
Gerd A. Guenther/Nikon Small World
Ever wonder what sex between two freshwater ciliates looks like magnified at 630 times its actual size? Now you know!
Joan Rohl, Institute for Biochemistry and Bio
This freshwater water flea is shown at 100 times its actual size.
Wolfgang Bettighofer/Nikon Small World
Closterium lunula, a kind of green alga, is shown here. This particular specimen came from a bog pond, according to the photographer.
John Gaynes, University of Utah/Nikon Small W
While it may resemble a visitor from outer space, this is what a zebrafish embryo looks like under a microscope, three days after being fertilized.
Dr. Carlos Alberto Muñoz, University of Puer
This microscopic crustacean appears yellowish-orange because it is mounted in Canada Balsam with crystals and other artifacts.
A U.S. advisory board on Wednesday debated a controversial new technique that would use DNA from three people to produce embryos free of a particular type of hereditary disease.
The panel, which provides independent advice to the Food and Drug Administration, weighed whether a procedure that replaces part of a human egg cell with that of another is safe for clinical trials.
The procedure has thus far been tested only on monkey embryos.
Proponents of the technique called "three-parent in vitro fertilization" say the measure has huge medical potential while detractors say it could lead to custom-made "designer babies."
At the center of debate lie mitochondria, a structure where most of a cell's energy is created, that also contains DNA separate from the 23 chromosomes in a cell's nucleus.
Each year some 1,000 to 4,000 children born in the United States develop mitochondrial diseases, which often affect the central nervous system or cause blindness or heart problems.
The diseases, which generally become evident before age ten, often result from genetic abnormalities in mitochondria, which are passed down from a child's mother.
Under the procedure, a disease-producing mitochondria in an egg is replaced with another woman's mitochondria, before the egg is then fertilized in a laboratory and implanted in the mother.
Shoukhrat Mitalipov, the scientist at Oregon Health and Science University who created the procedure, successfully oversaw the birth of five monkeys using the technique.
He would now like to pursue clinical trials on humans.
In 2001, using a different technique, U.S. scientists carried out successful three-parent fertilization experiments which resulted in the birth of some 20 children.
But the FDA asked them to halt the procedure on humans.
The Center for Genetics and Society, a Washington group opposed to the procedure, organized a petition against its approval.
"This is a biologically extreme procedure that puts any resulting children at serious risk, and that breaks a long-standing international consensus against producing genetically engineered humans" said director Marcy Darnovsky.
"The technique ... raises grave safety and social concerns. It carries a wide range of predictable and unpredictable risks for any resulting children and for future generations," she said.
Some 40 countries, including many with large biotechnology and advanced biomedical sectors, have adopted laws forbidding similar genetic modifications, Darnovsky emphasized.
Susan Solomon, CEO of the New York Stem Cell foundation told The Washington Post that people's feelings on the procedure should not be motivated by a fear of the unknown.
"There are no designer babies here," she said. "We are trying to stop a horrible, horrible disease."