Spaceflight decelerates the epigenetic clock orchestrated with a global alteration in DNA methylome and transcriptome in the mouse retina

This research paper explores how going into space can affect the genes and DNA methylation patterns of astronauts, which could potentially harm their eyesight or nervous system functioning during long-term missions like those on the International Space Station (ISS). The study looked at changes in gene activity levels before and after spaceflight. To understand these genetic shifts better, scientists used a technique called Principal Component Analysis (PCA) to group similar patterns together from thousands of data points representing different parts of astronauts' DNA that changed during their time in space. This helped them identify which gene changes might be connected and could lead to health issues like vision problems or damage to the nervous system, particularly affecting the eyes and retinas (the part at the back of your eye responsible for seeing). The researchers found out these genetic alterations are linked with oxidative stress-a type of cellular imbalance that can cause cells to die off. This is concerning because it could explain why astronauts often experience vision problems after returning from space, as well as other health issues related to the nervous system and eyesight in general.

This research paper investigates the functional enrichment of gene expression changes induced by spaceflight using differentially expressed genes (DEGs) and differentially methylated genomic regions (DMGs). The study employs principal component analysis (PCA) to analyze normalized gene expression counts, specifically focusing on 177 DEGs. To address missing values in the input data, an imputation method using 'imputePCA' from the R package 'missMDA' is applied before performing PCA with the function 'prcomp' from the R package 'stats'. The contributions of each principal component (PC) are then extracted through eigenvalue analysis. The introduction highlights that spaceflight poses two major risk factors: irradiation and microgravity, which may lead to adverse effects on astronauts’ vision and central nervous systems. Studies have shown a significant number of eye problems in returning astronauts from Space Shuttle missions or the International Space Station (ISS), with more than 30% diagnosed cases resulting in reduced visual acuity.