Natalia M. Jiménez Vizcarrondo^1*, Demi Geneva Fortson²,  Erin L. Barnhart^2
1Department of Biology, University of Puerto Rico, Rio Piedras, San Juan, PR
²Department of Biological Science, Columbia University, New York, U.S.

INTRODUCTION:

Proper neuronal function relies heavily on high-energy demands, primarily met through mitochondrial oxidative phosphorylation (OXPHOS). While glial cells are believed to support neuronal metabolism by shuttling glycolytic byproducts, such as lactate, to neurons, in vivo studies have demonstrated that suppressing lactate transporters in glial cells significantly impairs fly viability. Surprisingly, recent findings from the Barnhart lab challenge the conventional perception that glial cells solely rely on glycolysis and possess smaller mitochondria. Instead, they have revealed the presence of large and highly branched mitochondria in glial cells. However, the significance of mitochondrial morphology in glial cells remains unanswered.

METHODS:

To investigate the role of mitochondrial morphology in glial cells, I propose manipulating the expression of MARF, a pro-fusion factor regulating mitochondrial morphology, using the GAL4/UAS system in Drosophila melanogaster’s well-characterized visual system. Overexpression of MARF aims to enlarge mitochondria within glial cells, while RNAi knockdown will reduce their size. Evaluation of the outcomes will involve fixing and staining Drosophila brains, followed by confocal microscopy imaging. Additionally, viability scoring and behavioral assays will be conducted to assess neuronal function.

RESULTS:

Upon genetic manipulation of MARF expression levels, distinct alterations in mitochondrial morphology within glial cells are anticipated. Overexpression is expected to yield enlarged and highly branched mitochondria, while RNAi knockdown will result in a reduction in size. Visual examination through confocal microscopy will provide insights into the changes in mitochondrial structure. Viability scoring and behavioral assays will further reveal the impact of these alterations on Drosophila viability and neuronal function. Preliminary data has indicated an effect on the fly’s viability. However, at the moment, no conclusive statements can be made as more data is needed to confirm the experiment’s outcomes.

CONCLUSION:

This study aims to elucidate how mitochondrial morphology in glial cells influences fly viability. This study aimed to elucidate the influence of mitochondrial morphology in glial cells on fly viability and behavior by manipulating MARF expression. The analysis of the data revealed significant differences in both upregulating and downregulating MARF compared to the control group. While our findings indicate an impact on fly viability, further data collection is necessary to formally conclude the functional significance of large and branched mitochondria in glial cells and their relationship to neuronal health in Drosophila melanogaster.

ACKNOWLEDGEMENT:

I would like to acknowledge Erin L. Barnhart and the collaboration of the Barnhart lab members, with special recognition for Demi Geneva Fortson and Hailey Wang for their invaluable support on this project. I would also like to extend my gratitude to Dr. Alfredo Ghezzi for his guidance within my research career. Additionally, I express my gratitude to The Leadership Alliance for providing me with the opportunity to conduct this research and for their continued support.