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In 1978, James Kitching discovered two dinosaur embryos in a road-cut talus at Roodraai (Red Bend) in Golden Gate Highlands National Park, South Africa. Kitching assigned the fossilized embryos to the species of long necked herbivores Massospondylus carinatus (longer vertebra) from the Early Jurassic period, between 200 and 183 million years ago. The embryos were partially visible but surrounded by eggshell and rock, called matrix. Kitching said that the eggs were too delicate to remove from the matrix without damage.
The Southern Gastric Brooding Frog (Rheobotrahcus silus) was a frog species that lived in Australia. It was declared extinct in 2002. Once adult males fertilized the eggs of females, the females swallowed their eggs. The stomachs of the females then functioned somewhat like wombs, protecting the eggs while they gestated. Once the eggs developed into juveniles, female frogs performed oral birth and regurgitated their young.
Thalidomide is a sedative drug introduced to European markets on 1 October 1957 after extensive testing on rodent embryos to ensure its safety. Early laboratory tests in rodent populations showed that pregnant rodents could safely use it, so doctors prescribed Thalidomide to treat morning sickness in pregnant women. However, in humans Thalidomide interfered with embryonic and fetal development in ways not observed in rodent tests.
The first successful cloning of a gaur in 2000 by Advanced Cell Technology involved the cells of two animals: an egg cell from a domestic cow and a skin cell from a gaur. The researchers extracted the egg cell from the ovary of the domestic cow and the skin cell from the skin of the gaur. First, the researchers performed nuclear transplantation on the egg cell of the cow, during which they removed the nucleus of the egg cell. The mitochondria of the egg cell remained intact inside the cell.
The Southern Gastric-Brooding Frog (Rheobatrachus silus) was an aquatic frog that lived in south-east Australia. In 2002, the International Union for Conservation of Nature Red List declared the frog extinct, although no wild specimens had been reported since 1981. As the common name alludes to, the R.
Bacteria of the genus Wolbachia are
bacteria that live within the cells of their hosts. They infect a
wide range of arthropods (insects, arachnids, and crustaceans) and
some nematodes (parasitic roundworms). Scientists estimate that
Wolbachia exist in between seventeen percent and seventy-six percent of
arthropods and nematodes. The frequency of the bacteria makes them
one of the most widespread parasites. In general, they are divided
into five groups, from A to E, depending of the species of their
When cells-but not DNA-from two or more genetically distinct individuals combine to form a new individual, the result is called a chimera. Though chimeras occasionally occur in nature, scientists have produced chimeras in a laboratory setting since the 1960s. During the creation of a chimera, the DNA molecules do not exchange genetic material (recombine), unlike in sexual reproduction or in hybrid organisms, which result from genetic material exchanged between two different species. A chimera instead contains discrete cell populations with two unique sets of parental genes.
“The Science and Ethics of Making Part-Human Animals in Stem Cell Biology” (2006), by Jason Scott Robert
In 2006, bioethicist Jason Scott Robert published “The Science and Ethics of Making Part-Human Animals in Stem Cell Biology” in The FASEB Journal. There, he reviews the scientific and ethical justifications and restrictions on creating part-human animals. Robert describes part-human animals, otherwise known as chimeras, as those resulting from the intentional combination of human and nonhuman cells, tissues, or organs at any stage of development.
All cells that have a nucleus, including plant, animal, fungal cells, and most single-celled protists, also have mitochondria. Mitochondria are particles called organelles found outside the nucleus in a cell's cytoplasm. The main function of mitochondria is to supply energy to the cell, and therefore to the organism. The theory for how mitochondria evolved, proposed by Lynn Margulis in the twentieth century, is that they were once free-living organisms.