A key aspect of life is sex. Organisms that proliferate sexually increase their genetic diversity by mixing and recombining their genetic information. Gene shuffling by sexual reproduction may thereby be an advantage for a population as it may help a species to survive in an unpredictably variable environment because the probability of having the combinations of features necessary for survival in a changing environment increases with an increasing number of gene combinations.
In fission yeast and other organisms the successful mixing and recombining of the chromosomes, which are located inside the nucleus, requires concerted movement of the nucleus. The movement is driven by molecular motors that move the nucleus back and forth inside the cell with the aid of the cytoskeleton. (A central question is how motors work together to produce large-scale movements of the nucleus.)
In this picture we look at a living fluorescent fission yeast zygote while having sex under the microscope! This zygote is the result of two cells that merged before and now shuffle their genes. The microtubules - here, marked in red - are physically connected to the nucleus, which contains the chromosomes. In green you can see the motor protein dynein, which is pulling on the microtubules and thereby moves the nucleus back and forth. This movement shakes and mixes the chromosomes so that they can recombine.
Sven Vogel, Tolic-Norrelykke group at MPI-CBG Dresden
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