molecular biology

The origin and the process by which eukaryotic cells—the cells that make up animals, plants and fungi—first emerged remains one of the great unanswered questions in biology. The prevailing explanation, put forward by biologist Lynn Margulis, identified the union between an archaeon and a bacterium as the turning point. Now, a study carried out by IRB Barcelona and the Barcelona Supercomputing Center re-examines and expands on the current theory. The findings, published in the journal *Nature*, suggest that the process was longer and more complex than previously thought. At least two other different bacteria contributed to the development of eukaryotic cells, and giant viruses appear to have acted as vehicles for gene transfer. To explain the study, the Science Media Centre Spain organised a briefing with Toni Gabaldón, the lead researcher on the paper.

The origin and the process by which eukaryotic cells arose remains one of the great unanswered questions in biology, with Lynn Margulis’s theories regarding the incorporation of a bacterium that would later become the mitochondrion marking a major turning point. Now, Spanish research carried out by IRB Barcelona and the Barcelona Supercomputing Center challenges this view. Without denying the role of mitochondria, it suggests that the process was longer and more complex than previously thought, stretching over hundreds of thousands of years. At least two other different bacteria contributed to the development of eukaryotic cells, and giant viruses appear to have acted as vehicles for genetic transfer. The findings, published in Nature, suggest a much more protracted and gradual process of exchange between microorganisms.

Sea cucumbers are known for their regenerative capacity and for exhibiting minimal cellular ageing. An article published in the journal Science Advances has documented the viability of amputated tissue from the species Psolus fabricii for over three years in natural seawater. Samples taken from three individuals of this species showed cellular diversification, immune activity, tissue reorganisation and the uptake of dissolved amino acids—properties that are unparalleled in the current scientific literature, according to the article. The authors also note that the finding may pave the way for a new experimental model, free from ethical concerns, for regenerative biology, biomedical research and tissue engineering.

The so-called 'dark transcriptome' consists of non-coding RNA, i.e. RNA that does not provide instructions for building proteins. A study published in the journal Science Signaling used long non-coding RNAs (lncRNAs) and modified them to attenuate acute inflammation in mice and human cells. The authors are confident that this could open up a new field of therapeutic development.

A new study conducted over 25 years with data from 2,766 older women, who were in good cognitive health at the start, shows that high blood levels of the p-tau217 protein were strongly associated with future mild cognitive impairment and dementia. In its press release, the University of California (United States), where the authors work, stated that ‘a new blood biomarker can predict a woman's risk of developing dementia up to 25 years before symptoms appear.’ The study is published in the journal JAMA Network Open.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterised by progressive loss of motor neurons. An international team has discovered evidence that ALS may have an autoimmune component, meaning that the immune system mistakenly attacks healthy cells, a hypothesis that had been considered by the scientific community. The study shows that inflammatory immune cells—called CD4+ T cells—attack certain proteins that are part of the nervous system in people with ALS. ‘These findings highlight the potential of therapeutic strategies aimed at improving regulatory T cells,’ the authors note in the research, published in Nature.

A team has managed to visualise and quantify the protein aggregates believed to trigger Parkinson's disease. This is the first time they have been directly visualised. These small aggregates – alpha-synuclein oligomers – were observed in post mortem brain tissue from people with the disease using a new microscopy technique, as explained by the authors in Nature Biomedical Engineering.

Most rare diseases are caused by mutations in DNA, but the same gene can mutate in different ways, which complicates treatment. Now, a team from the CRG in Barcelona has shown that an already approved drug is capable of stabilising almost all mutated versions of a human protein—specifically, the vasopressin V2 receptor, which is linked to a rare disease called nephrogenic diabetes insipidus. According to the researchers, who published their findings in Nature Structural & Molecular Biology, the study is the first proof of concept demonstrating that a drug can act as a ‘near-universal’ treatment, which could accelerate the development of therapies.

The research article A bacterium that can grow by using arsenic instead of phosphorus was one of the big science stories because it discussed the possibility of arsenic-based life. However, it has been the subject of criticism until now. After nearly 15 years of debate and failed attempts by other groups to replicate the findings, Science has now decided to retract the article, despite finding no evidence of fraud or misconduct on the part of the authors, who disagree with the decision.

A team from Sweden has analysed post mortem brain samples from people aged between 0 and 78 using various techniques and found that, although it varies between individuals, new neurons continue to form in the hippocampus with no apparent age limit. Although previous studies had reached similar conclusions, controversy remains about these results. According to the authors, the new work ‘provides an important piece of the puzzle in understanding how the human brain works and changes throughout life.’ The results are published in the journal Science.