Saari Sina, Andjelković Ana, Garcia Geovana S, Jacobs Howard T, Oliveira Marcos T
Institute of Biosciences and Medical Technology, Tampere University Hospital, University of Tampere, FI-33014, Tampere, Finland.
Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, 14884-900, Brazil.
BMC Dev Biol. 2017 Jul 3;17(1):9. doi: 10.1186/s12861-017-0151-3.
Mitochondrial alternative respiratory-chain enzymes are phylogenetically widespread, and buffer stresses affecting oxidative phosphorylation in species that possess them. However, they have been lost in the evolutionary lineages leading to vertebrates and arthropods, raising the question as to what survival or reproductive disadvantages they confer. Recent interest in using them in therapy lends a biomedical dimension to this question.
Here, we examined the impact of the expression of Ciona intestinalis alternative oxidase, AOX, on the reproductive success of Drosophila melanogaster males. Sperm-competition assays were performed between flies carrying three copies of a ubiquitously expressed AOX construct, driven by the α-tubulin promoter, and wild-type males of the same genetic background.
In sperm-competition assays, AOX conferred a substantial disadvantage, associated with decreased production of mature sperm. Sperm differentiation appeared to proceed until the last stages, but was spatially deranged, with spermatozoids retained in the testis instead of being released to the seminal vesicle. High AOX expression was detected in the outermost cell-layer of the testis sheath, which we hypothesize may disrupt a signal required for sperm maturation.
AOX expression in Drosophila thus has effects that are deleterious to male reproductive function. Our results imply that AOX therapy must be developed with caution.
线粒体交替呼吸链酶在系统发育上广泛存在，可缓冲影响拥有这些酶的物种中氧化磷酸化的应激。然而，在导致脊椎动物和节肢动物的进化谱系中，它们已经消失，这就引发了一个问题，即它们会带来哪些生存或繁殖劣势。最近对在治疗中使用它们的兴趣为这个问题增添了生物医学层面的考量。
在此，我们研究了玻璃海鞘交替氧化酶（AOX）的表达对黑腹果蝇雄性繁殖成功率的影响。在携带由α -微管蛋白启动子驱动的三个拷贝的普遍表达AOX构建体的果蝇与相同遗传背景的野生型雄性果蝇之间进行精子竞争试验。
在精子竞争试验中，AOX带来了显著劣势，这与成熟精子产量降低有关。精子分化似乎一直进行到最后阶段，但在空间上出现紊乱，精子细胞保留在睾丸中而不是释放到精囊中。在睾丸鞘的最外层细胞层中检测到高AOX表达，我们推测这可能会破坏精子成熟所需的信号。
因此，果蝇中AOX的表达对雄性生殖功能具有有害影响。我们的结果意味着必须谨慎开发AOX疗法。
