Civilian spaceflight prompted researchers to study spaceflight effects on human physiology, focusing at the molecular level.

Long-read RNA sequencing of astronaut blood showed genetic pathway changes like erythrocyte regulation, stress induction, and immune changes influenced by spaceflight, along with a significant increase in m6A levels post-flight.

Contributions of the Paper

Revealed key genetic pathways influenced by spaceflight, such as changes in erythrocyte regulation, stress induction, and immune responses .

Provided the first m6A methylation profiles for a human space mission, indicating a notable increase in m6A levels post-flight .

Presented longitudinal long-read RNA profiles and RNA modification maps, enhancing understanding of the dynamic response of the human transcriptome to spaceflight .

Utilized nanopore-based sequencing technologies for whole-blood analysis to map changes in gene expression and chemical structure at the single-molecule level .

Practical Implications of the Paper

Understanding genetic pathways affected by spaceflight can help in developing targeted interventions to mitigate physiological changes in astronauts .

Knowledge of increased m6A methylation levels post-flight can aid in designing strategies to counteract these changes and maintain astronaut health .

Longitudinal RNA profiles and modification maps can guide the development of personalized countermeasures to support astronaut well-being during and after space missions .

The use of nanopore-based sequencing technologies showcases the potential for advanced molecular analysis in space research, paving the way for more comprehensive studies on human physiology in space.

Methods

Direct RNA sequencing

Total RNA from astronaut blood samples was processed using the direct-RNA kit from Oxford Nanopore Technologies, allowing for detailed sequencing of RNA molecules.

Basecalling and alignment of raw nanopore events were performed to assess RNA modifications and gene expression profiles accurately.

Quality assessment tools like pycoQC and MultiQC were utilized to ensure the reliability and accuracy of the direct RNA sequencing data.

Differential gene expression analysis

Two computational pipelines were employed to quantify gene expression and identify DEGs, providing comprehensive insights into the transcriptional responses of astronauts to spaceflight.

Differential expression analysis focused on aligning reads to the human transcriptomic reference and genome reference, utilizing tools like salmon, edgeR, and DESeq2 for accurate gene quantification and DEG detection.

Covariates were included to account for inter-astronaut variability, and only genes identified as significantly differentially expressed by both DESeq2 and edgeR were considered for further analysis.

The study highlighted the importance of comparing different approaches to gene expression analysis to ensure robust and reliable results for understanding the effects of spaceflight on gene regulation.

Gene set co-regulation analysis

Gene set co-regulation analysis was conducted to examine changes in known pathways and molecular functions associated with spaceflight, revealing significant variability in pathways post-spaceflight.

Pathways were ranked based on their disruption levels, providing insights into the impact of spaceflight on gene expression patterns and pathway activities.

The analysis emphasized the dynamic nature of pathway variability upon return from spaceflight, indicating the complex interplay between gene expression changes and pathway responses to spaceflight stressors.

Results

Two distinct computational approaches were used to analyze gene expression quantification and differentially expressed genes (DEGs) from direct RNA data, providing insights into the effects of short-term space flight.

Gene set co-regulation analysis revealed significant changes in pathways associated with spaceflight, particularly highlighting upregulated genes and pathways related to erythrocyte functions.

Longitudinal changes in differentially enriched pathways showed disrupted trends immediately post-spaceflight or continued changes during recovery, indicating the dynamic nature of gene expression responses to spaceflight.

Transcription factor enrichment analysis identified key regulators like KLF1, GATA1, and TAL1, emphasizing their role in hematopoietic responses to spaceflight.

Discussion

The study discusses the unique signature of disrupted gene regulation observed in astronauts post-spaceflight, particularly focusing on hematological responses and m6A modifications.

Spaceflight-induced changes in gene expression and pathways were attributed to various factors like radiation exposure, gravity alterations, circadian rhythm disruptions, and mission stress.

The study highlights the importance of understanding the interplay between gene expression, RNA modifications, and pathway activities in response to spaceflight stressors.

Future research directions include replicating findings in other missions, exploring new features of the transcriptome, and optimizing sequencing technologies for real-time monitoring during space missions.