Mitochondrial Respiration in Drosophila Ovaries after a Full Cycle of Oogenesis under Simulated Microgravity

Abstract

Studies of the function of the female reproductive system in zero gravity are urgent for the future exploration of deep space. Female reproductive cells, oocytes, are rich in mitochondria, which allow oocytes to produce embryos. The rate of cellular respiration was determined to assess the functional state of the mitochondrial apparatus in Drosophila melanogaster ovaries in which the full cycle of oogenesis took place under simulated microgravity. Since cellular respiration depends on the state of the cytoskeleton, the contents of the main cytoskeletal proteins were determined by Western blotting. To modulate the structure of the cytoskeleton, essential phospholipids were administered per os at a dosage of 500 mg/kg in medium. The results of this study show that after a full cycle of oogenesis under simulated microgravity, the rate of cellular respiration in the fruit fly ovaries increases, apparently due to complex II of the respiratory chain. At the same time, we did not find any changes in the area of oocytes or in the content of proteins in the respiratory chain. However, changes were found in the relative contents of proteins of the actin cytoskeleton. There were no changes of essential phospholipids and no increase in the rate of cellular respiration of the ovaries after exposure to simulated microgravity. However, in the control, the administration of essential phospholipids led to a decrease in the efficiency of oxygen consumption in the flies’ ovaries due to complexes IV–V.

State of Drosophila melanogaster Ovaries after a Full Cycle of Gametogenesis under Microgravity Modeling: Cellular Respiration and the Content of Cytoskeletal Proteins

“…Therefore, we determined the content of alpha-actinin and recorded an increase in its content. Moreover, in our previous study, after a short-term experiment under the simulated microgravity of Drosophila melanogaster, cellular respiration also increased, and we noted an increase in the content of alpha-actinin [29]. In addition, the relative content of beta-actin also increased.…”

Single Cell in a Gravity Field

“…In the ovaries of flies, during the complete cycle of oogenesis, which took place under conditions of simulated microgravity, we found an increase in cellular respiration, and, according to inhibitory analysis, apparently due to complex II of the respiratory chain against the background of a constant content of proteins of the respiratory chain and the area of oocytes in ovarioles [ 103 ]. We associated these changes with the observed decrease in the content of the actin-binding protein alpha-actinin and beta-actin, which in turn can activate the transcription factor STAT3 [ 104 ], which can activate cellular respiration due to the activation of complexes I and II of the mitochondrial respiratory chain [ 105 , 106 , 107 ].…”

“…We associated these changes with the observed decrease in the content of the actin-binding protein alpha-actinin and beta-actin, which in turn can activate the transcription factor STAT3 [ 104 ], which can activate cellular respiration due to the activation of complexes I and II of the mitochondrial respiratory chain [ 105 , 106 , 107 ]. Moreover, the introduction of essential phospholipids prevents all changes caused by microgravity [ 103 ]. However, if flies from a zygote to a 2-day-old individual developed under conditions of simulated microgravity, we also observed an increase in the intensity of cellular respiration, but at the expense of complex I of the respiratory chain.…”

Drosophila melanogaster Oocytes after Space Flight: The Early Period of Adaptation to the Force of Gravity

“…Based on the data in the literature [ 3 , 4 , 23 ] and our own studies [ 5 , 6 ], we expected to detect changes in the structure of the oocyte cytoskeleton and planned to evaluate its dynamics. However, few oocytes were obtained, especially in the first 12 h after landing, which made it possible to evaluate only one parameter.…”

“…In mouse oocytes cultured in simulated weightlessness for up to 16 hours, abnormal spindle formation took place, probably as a result of gamma-tubulin redistribution [ 4 ]. Similarly, under the conditions of simulated microgravity in the ovaries of flies, there are also changes in cellular respiration (mediated by mitochondria) and various changes in the structure of the cytoskeleton [ 5 , 6 ]. Moreover, changes in the functional status of mitochondria can also be mediated by the cytoskeleton [ 7 ].…”