Genes get shuffled and re-dealt with every new generation, meaning many are relatively recent. But while exploring the “dark heart” of the human genome, geneticists have now found some of the most ancient pieces of DNA, inherited from Neanderthals and an as-yet-unknown human relative, which may be affecting our sense of smell to this day.

What causes the immune system, designed to protect us, to turn on the body and attack healthy cells? Common bacteria that reside in the human gut may be partly to blame, say Yale researchers, who studied the origins of a serious autoimmune disease that frequently affects young women.

For their study, the research team focused on cells from patients with antiphospholipid syndrome, an immune system disorder that raises the risk of blood clots. This chronic condition can lead to lung clots, strokes, heart attacks, and in pregnant women, miscarriages or still births.

Using patient immune cells and antibodies, as well as animal models of the disease, the investigators did several experiments to explore the phenomenon. They found that a common gut bacterium, Roseburia intestinalis, can trigger the disease in individuals who have a genetic predisposition. In those patients, the immune system’s defender T and B cells react to a blood protein involved in clotting, and also to the bacteria, in certain amino acids found in the bacteria. Over time, this ongoing “cross-reactive” response leads to tissue damage and chronic disease.

But could hackers abscond with your genetic information?

Knowledge of the kinds and numbers of nuclear point mutations in human tissues is essential to the understanding of the mutation mechanisms underlying genetic diseases. However, nuclear point mutant fractions in normal humans are so low that few methods exist to measure them. We have now developed a means to scan for point mutations in 100 bp nuclear single copy sequences at mutant fractions as low as 10^–6.Beginning with about 10 human cells we first enrich for the desired nuclear sequence 10 000-fold from the genomic DNA by sequence-specific hybridization coupled with a biotin–streptavidin capture system. We next enrich for rare mutant sequences 100-fold against the wild-type sequence by wide bore constant denaturant capillary electrophoresis (CDCE). The mutant-enriched sample is subsequently amplified by high fidelity PCR using fluorescein-labeled primers. Amplified mutant sequences are further enriched via two rounds of CDCE coupled with high fidelity PCR. Individual mutants, seen as distinct peaks on CDCE, are then isolated and sequenced. We have tested this approach by measuring N-methyl–N ′-nitro–N-nitrosoguanidine (MNNG)-induced point mutations in a 121 bp sequence of the adenomatous polyposis coli gene (APC) in human lymphoblastoid MT1 cells. Twelve different MNNG-induced GC→AT transitions were reproducibly observed in MNNG-treated cells at mutant fractions between 2 × 10^–6 and 9 × 10^–6. The sensitivity of this approach was limited by the fidelity of Pfu DNA polymerase, which created 14 different GC→TA transversions at a mutant fraction equivalent to ~10^–6 in the original samples. The approach described herein should be general for all DNA sequences suitable for CDCE analysis. Its sensitivity and capacity would permit detection of stem cell mutations in tissue sectors consisting of ~10 cells.

This is where it gets a little weird.

When the team treated human cells in culture with extract of tardigrade, the GFP-tagged proteins stuck to human DNA just like they stick to tardigrade DNA, and cheerfully started doing what they do best: tamping down oxidative stress. When X-rays hit human cells, they do two kinds of damage. X-rays can cause direct DNA strand breaks, which are mostly single-strand. When they strike water molecules, they can also excite them into producing reactive oxygen species, which also cause single-strand breaks. High enough doses of X-rays can cause double-strand breaks. The damage-suppressing protein Dsup went immediately to work on the culture of human cells, suppressing or repairing single-strand and double-strand breaks by about 40%.

Clearly this means we can consume water bears to gain their powers. The study authors remark that the gene portfolio of the tardigrade represents “a treasury of genes” to improve or augment stress tolerance in other cells. Plug-and-play genetics, anyone?