Frenkel J K, Dubey J P, Hoff R L
J Protozool. 1976 Aug;23(3):421-4. doi: 10.1111/j.1550-7408.1976.tb03799.x.
Toxoplasma gondii, passed from mouse to mouse in the tachyzoite stage for 30-35 generations, developed cysts, which when fed to cats, failed to produce oocysts. Besnoitia jellisoni, passed similarly for 20 generations, lost the capacity to form cysts. These phenomena are explained by a loss of genomes or gene products during the rapid passage selecting for tachyzoites.
刚地弓形虫在速殖子阶段在小鼠间传代30至35代后形成了包囊，将这些包囊喂给猫后却未能产生卵囊。杰氏贝诺孢子虫以同样方式传代20代后，失去了形成包囊的能力。这些现象可以用在选择速殖子的快速传代过程中基因组或基因产物的丢失来解释。
