When asked about the most unique creatures, perhaps the answer is Tetrahymena thermophila. This creature consisting only of a single cell, but had seven sexes.
Of course sex is not referred to as male or female. Scientists refer to the type. So, there are type I to type VII. Each cell can mate with another cell, except that one type with it.
Although a seven sexes, T. thermophila arguably not a species like mating. They prefer asexual reproduction.
When asexual reproduction, cell T. thermophila divides into two identical cells. One of two owned cell nucleus, called germline nucleus, did not do anything. Only other genes in the cell nucleus, called somatic nucleus, is activated.
Sexual reproduction is only done when food availability is reduced. Sexual reproduction allows genetic recombination, allowing produce offspring that are more resistant to challenge.
Eduardo Orias, a biologist at the University of California, Santa Barbara, as quoted by National Geographic, Thursday (25/04/2013), said the extreme conditions also led to the development of many types of sex.
"If you only have 2 genders, there is only a 50 percent chance to find the right type. If there are 7 kinds of sex, opportunities to meet the right type increased to 85 percent," he said.
Scientists already know that T. thermophila has seven sexes since the 1950s. However, this was the first time scientists have solved the puzzle of determining the sex of this species.
To solve the puzzle jensi sex determination, the scientists examined the strain Tetrahymena than T. thermophila who only have six sexes. Strain was forced into marriage by making poor food environment.
In the study, scientists compared the genes expressed during mating and when normal growth.
As a result, scientists identified a pair of genes that are active only during mating. When the gene is disabled, no longer Tetrahymena mating. Is a candidate gene for sex determination genes related.
Scientists then sort the Tetrahymena genome. They get six copies of the gene in the germline nucleus. One copy to one sex.
In further experiments, scientists found that Tetrahymena will sort, cut, and rearrange the six pairs of genes until only one pair left. One pair will be in the somatic nucleus.
A pair of such genes will dieskpresikan in Tetrahymena cell membrane so that sex can be known.
Orias and his team stated, Tetrahymena understand important to develop an understanding of how a species' mating and how genetic recombination. Understanding of genetic recombination could help the development of immune function and cancer cells.
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