Past Biology Experiments

EoI-45-25
Corresponding author: jiranzo@cab.inta-csic.es

The project set out to investigate how low background radiation levels might influence the evolution of Escherichia coli. The research aimed to analyse changes in the mutational spectrum of the bacteria and their ability to adapt, including their response to antibiotics. The overall objective was to understand how the absence or reduction of environmental radiation might alter the processes of mutation and selection during bacterial evolution, as well as the mechanisms used by populations to adapt to these conditions.

The experiment could not be carried out, as it required experimental work to be conducted at weekends and it is currently not possible to provide this type of support at the LSC.

EoI-41-24
Spokesperson: lribas@icm.csic.es

The GraCosFish project investigated the effects of microgravity and cosmic radiation on the early stages of development in aquatic vertebrates. Between October 2024 and January 2026, a number of experiments were carried out using zebrafish and European sea bass embryos, combining simulated microgravity conditions with different levels of ambient radiation. Microgravity was simulated using a clinostat that kept the embryos in continuous rotation during the first five days of development.

At the end of the experiments, the larvae were stored at low temperature for subsequent transcriptomic and epigenetic analyses. These analyses enabled the study of changes in gene expression and DNA methylation associated with exposure to microgravity. This first experimental phase has now been completed and a scientific article detailing the results is currently being prepared.

EoI-40-2023
Spokesperson: dstepanova@crm.cat

The project investigated how low background radiation levels can affect fundamental cellular functions and physiological balance. The first phase focused on two aspects: mitochondrial function in the yeast Saccharomyces cerevisiae and the activity of enzymes involved in defence against oxidative stress. In this regard, enzymatic assays were carried out to study the activity of enzymes involved in cellular protection against oxidative stress.

With the completion of these assays, the first phase of the project was concluded. The work carried out established an experimental basis for continuing to study DNA repair mechanisms, as well as for further investigating and verifying the results obtained through the analysis of the activity of other enzymes involved in the response to oxidative stress.

This research project is currently continuing as a collaboration between the researchers leading the experiment and the LSC.

EoI-39-2022
Spokesperson: jmenendez@idibgi.org

The study analysed the response of human cells to cellular damage under conditions of reduced cosmic radiation. To this end, cancerous and non-cancerous cells with different DNA response and repair mechanisms were used and subjected to various treatments capable of inducing senescence. The experiments were carried out both in the underground laboratory, where muon exposure is very low, and in the surface laboratory, which served as a control.

During the study, various indicators of senescence were assessed to compare the cellular response under both environmental conditions. The analysis covered both changes directly associated with the senescence process and others related to the cellular response to damage and gene expression, enabling researchers to investigate whether the intensity of cellular stress influenced the response observed under different levels of environmental radiation.

The results of this study have been published in the following article:

• Llop-Hernández, À., López, J., Verdura, S., Hernández-Antolín, R., Cid-Barrio, L., Peña-Garay, C., Alarcón, T., Cuyàs, E., & Menendez, J. A. (2026). Cellular Senescence in the Absence of Galactic Cosmic-Ray Muons. Aging And Disease. https://doi.org/10.14336/ad.2026.0025

EoI-35-2021
Spokesperson: inaki.ruiz@ibe.upf-csic.es

The aim of the project was to study the impact of low levels of environmental radiation on single-celled microorganisms that are evolutionarily closely related to animals, both at the genomic level and in terms of processes related to the formation of multicellular structures. The two organisms selected were Sphaeroforma arctica and Capsaspora owczarzakii.

The experiment with S. arctica took place between February and September 2024. The cultures were maintained for six months under low-radiation conditions both underground and on the surface, with periodic transfers and the collection of samples for subsequent DNA and RNA analysis. Complementary experiments were also carried out to study the effects of low radiation and microgravity, as well as to monitor the cells using microscopy. Subsequently, between March and October 2025, experiments were carried out with Capsaspora owczarzaki, extending the study to another model microorganism. This experimental phase was brought to a close so that the subsequent stages of the research could be carried out within the framework of a new doctoral thesis proposal, conceived as a collaboration between the LSC and the research group.

EoI-37-2022
Spokesperson: irene.otero.muras@csic.es

The aim was to conduct a chronological longevity experiment on yeast, comparing their survival under low-radiation conditions and on the surface. Two experimental runs were carried out, in March 2023 and March 2024, using wild-type and mutant strains cultured in parallel under both conditions. In addition, different experimental techniques were explored, including viability and transcriptomic analyses, with the aim of studying the effects of environmental conditions from different perspectives.

Longevity was determined using a manual procedure that required a large number of measurements and replicates to obtain statistically significant results. The proposed strategy involved expanding the number of strains and techniques in order to corroborate the results using different experimental approaches. The experiment has been suspended pending the development of a new experimental proposal that would allow this line of research to be continued and completed.

EoI-30-2021
Spokesperson: jbuceta@gmail.com

The experiment investigated the effect of radiation, and in particular of muons, on the bacterial mutation rate. After first developing and validating a methodology adapted to the conditions at the LSC, two experimental campaigns were carried out: the first in January 2024 and the second in April 2024, comparing experiments conducted on the surface and in the underground laboratory. The initial results indicated a possible effect of muons on the mutation rate.

The second campaign exhibited variability that made it difficult to replicate the initial results. These difficulties led to the development of a new automated methodology, based on liquid cultures in multi-well plates, which reduces sample handling and potential sources of error. The new protocol has undergone preliminary validation tests but has not yet been applied in a new experimental campaign at the LSC, as it requires further optimisation and the laboratory does not currently have the necessary equipment for its direct implementation. This experiment has been put on hold pending a new proposal.

EoI-34-2021
Spokesperson: marc.guell@upf.edu

This experiment investigated the growth of different species of bacteria under various conditions of radiation exposure. To this end, two cell lines – Escherichia coli and Cutibacterium acnes – were used; their cultures were initially maintained in the absence of radiation and subsequently exposed to different sources, specifically UV and gamma radiation from a caesium source.

The results enabled an analysis of how the absence of radiation and different types of radiation affected the growth and condition of the bacteria. After two days of experimentation, the cultures were processed and frozen for subsequent analysis at the PRBB in Barcelona. This experiment was suspended pending a new proposal.

EoI-33-2021
Spokesperson: santiago.elena@csic.es

This experiment investigated how environmental conditions in space – in particular microgravity and radiation levels lower than those typically found on Earth’s surface – affect viral infections. To this end, the nematode Caenorhabditis elegans, infected with the Orsay virus, was used to analyse various parameters relating to its development, reproduction and physiological state under different combinations of gravity and radiation.

The results showed that microgravity and low levels of radiation affect the reproduction and development of infected organisms in different ways, as well as altering viral accumulation. The interaction between environmental conditions and infection produced complex effects, highlighting the need for further study into how space conditions may influence, in the long term, the response of organisms to infections and the interactions between hosts and pathogens.

The results of this study were published in the following article:

• Villena-Giménez, A., Castiglioni, V. G., Muñoz-Sánchez, J. C., Legarda, E. G., González, R., & Elena, S. F. (2026). Reduced gravity and muon flux absence affect Caenorhabditis elegans life history traits and viral infection. Microbiology Spectrum, 14(5), e0358025. https://doi.org/10.1128/spectrum.03580-25

EoI-29-2021
Spokesperson: fsobrino@cbm.csic.es

The experiment, which began at the LSC in October 2022, was launched after live bacteria were detected in high-purity heavy water (D₂O) that had been stored for 30 years in hermetically sealed containers. The aim was to study how these bacteria could survive in the apparent absence of external energy sources and to assess whether their survival might be linked to secondary cosmic radiation. To this end, samples of D₂O containing bacteria were incubated under different conditions of radiation exposure, both in the underground laboratory and at the surface, including controls in ultrapure water and D₂O without bacteria.s.

During the 30-month incubation period, the evolution of the bacterial populations was monitored periodically. However, the small volume of the samples and the use of a single container per condition made it difficult to obtain representative measurements. Furthermore, the formation of cell aggregates prevented the bacterial abundance from being quantified with sufficient precision and prevented a clear relationship from being established between bacterial survival and exposure to cosmic radiation. The results obtained have made it possible to identify these limitations and to guide the design of a new experiment using an improved methodology.