transdifferentiation

IMMORTAL JELLYFISH — request from elocinbored
Turritopsis nutricula
©Cibermitanios.com.ar

Turritopsis nutricula, the potentially immortal jellyfish, is a hydrozoan whose  jellyfish form can revert back to the polyp stage after becoming sexually mature. It is the only known case of a metazoan capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity.

It does this through the cell development process of transdifferentiation.

Cell transdifferentiation is when the jellyfish “alters the differentiated state of the cell and transforms it into a new cell”. In this process the mature jellyfish transforms back into the polyps stage creating a new polyp colony. Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal, although in nature, most Turritopsis, like other medusae, are likely to succumb to predation or disease in the plankton stage, without reverting to the polyp form.

No single specimen has been observed for any extended period, so it is not currently possible to estimate the age of an individual, and so even if this species has the potential for immortality, there is no laboratory evidence of many generations surviving from any individual.

Source: http://en.wikipedia.org/wiki/Turritopsis_nutricula

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22 June 2013

Brain Marrow

Converting one cell type into another – a process called transdifferentiation – doesn’t occur naturally in humans, or in most other creatures for that matter, though it can be induced artificially. But why would researchers want to make a cell switch identities? Well, just imagine if a patient had a disease where certain cells were damaged or dying. Making some of the patient’s other cells adopt the identity of the diseased cells could help to repair or replace the damaged tissue without the need for donor cells or organs. Researchers have now identified an antibody that binds to bone marrow cells and induces them to become nerve cells – their characteristic long skinny projections seen here (stained green) tipped with growth-directing regions called growth cones (stained red). Extracting a person’s bone marrow and converting it into nerve cells could potentially provide a convenient source of cells for repairing brain or spinal cord injury.

Written by Ruth Williams

The immortal jellyfish

Immortality in nature is not such a far-fetched thought after all. This is Turritopsis dohrnii, commonly known as the immortal jellyfish. With this guy it isn’t about living for a really long time: it can live its life over and over again, from start to finish, juvenile to adult, as many times as it wants.

Keep reading

Immortal jellyfish: Does it really live forever?

The Turritopsis nutricula jellyfish has displayed a remarkable ability to regenerate its cells in times of crisis.

While it is often joked that cats have nine lives, a certain species of jellyfish has been deemed “immortal” by scientists who have observed its ability to, when in crisis, revert its cells to their earliest form and grow anew. That means that these tiny creatures, 4 mm to 5 mm long, potentially have infinite lives.   The creature, known scientifically as Turritopsis nutricula, was discovered in the Mediterranean Sea in 1883, but its unique regeneration was not known until the mid-1990s. How does the process work? If a mature Turritopsis is threatened — injured or starving, for example — it attaches itself to a surface in warm ocean waters and converts into a blob. From that state, its cells undergo transdifferentiation, in which the cells essentially transform into different types of cells. Muscle cells can become sperm or eggs, or nerve cells can change into muscle cells, “revealing a transformation potential unparalleled in the animal kingdom,” according to the original study of the species published in 1996.   Since the Turritopsis’ virtual immortality was discovered, so have swarms of genetically identical jellyfish far from their original habitat, including in Japan, Spain and the Atlantic Ocean side of Panama. Researchers have concluded that these multiplying creatures are getting caught in ballast waters, water that is sucked into and pumped out of the long distance cargo ships. Polyps also could be growing on the ship’s hulls. Though genetically identical, these jellyfish seem to have adapted to their new environments. For example, specimens from swarms living in tropical waters have been found to have eight tentacles, while those discovered in temperate regions have 24 or more tentacles.   But Turritopsis can — and do — die. Their regeneration only occurs after sexual maturation, therefore they can succumb to predators or disease in the polyp stage. But because the jellyfish are the only known animal with this “immortality,” scientists are studying them closely, with the hopes of applying what they learn to issues such as human aging and illness.