Parthenogenesis is a reproductive strategy that sacrifices the genetic variation (a driving force of evolution) of sexual reproduction for the simple ability to reproduce. Small invertebrates, such as aphids, can use it to produce large numbers of females very quickly.
Larger organisms, such as Komodo dragons (Indonesia link!), have been known to use parthenogenesis in the absence of males, producing an all-male clutch of eggs. It is thought that this might allow them to set up new populations on isolated islands, using just a single female. Here’s a quick video of a Komodo dragon parthenogen hatching:
Generally, we use mitosis to replace and repair damaged cells and tissues and for growth and development – filling in the gaps with copied cells. Along the way, our cells differentiate to their function and we end up with a body full of specialised cells – each cell’s structure and biochemistry reflect its function.
All the offspring of organisms that reproduce sexually carry two copies of each chromosome – one from each parent – and each chromosome carries different alleles – ‘versions’ of each gene. This leads to a great deal of variation and this genetic diversity keeps the the population going.
What about uses in technology?
Funny you should ask that…
Induced parthenogenesis is being pursued as a method for obtaining embryonic stem cells. Read this New Scientist article to learn more.
Normally these parthenogenic embryos die after a few days, yet researchers are able to harvest them for stem cells for research. Ethically, these are considered engineered eggs, rather than human embryos. How do you feel about that?
So cloning is nothing new, but for the first time we see healthy lab mice cloned from the cells of dead mice – some articles are calling this a ‘resurrection’, although it is nothing of the sort.
It is, however, a big step forward for genetic reserach – lifting the possibility of cloning long-extinct species out of the realms of pure science fiction and into the ‘almost there’ zone. A team of Japanese researchers from Kobe, Japan, used a modified method to clone these mice from tissues that had been frozen for up to 16 years.
Here’s a clip from Japanese news, with a really clear section showing what looks like the insertion of the nucleus into an egg:
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