Virus-like DNA elements in animals may predate the split of major animal groups

A survey found envelope-carrying genetic elements in cnidarians, ctenophores, tunicates and other invertebrate animals.

Editorial illustration — not from the study.

Researchers searched invertebrate animal genomes for intact endogenous retroviruses—genetic elements that can copy themselves in a host’s germline and usually carry genes called gag and pol. They found elements related to the Ty3/gypsy group in cnidarians, ctenophores, tunicates and other metazoans.

The elements carried two main kinds of envelope genes, resembling proteins from paramyxoviruses or herpesviruses. Comparisons of their sequences and structures suggested that the envelope genes generally evolved alongside the elements’ pol genes and their animal hosts, with little recombination. The researchers say this pattern is consistent with an ancient association that predates the split between bilaterian and non-bilaterian animals.

Ancient envelope-carrying elements

The study identified intact, envelope-carrying endogenous retroviruses related to Ty3/gypsy elements across diverse invertebrate metazoans, including cnidarians, ctenophores and tunicates. Some animal genomes contained multiple highly similar copies, consistent with recent expansion within those host lineages. The envelope genes fell into two broad groups: ones resembling paramyxovirus glycoprotein F and ones resembling herpesvirus glycoprotein B. The two types were described as equally abundant and widespread. Phylogenetic and structural analyses found that envelope genes had largely diverged together with pol genes and their animal hosts, and had recombined infrequently. The researchers interpret these findings as evidence that envelope genes joined these retrotransposons before the split between bilaterian and non-bilaterian animals, during the Precambrian era.

A deeper animal history

The findings suggest that the association between self-copying genetic elements and envelope-like genes is not limited to a recent, lineage-specific event in fruit flies. Instead, it may have a much older history extending across major branches of the animal tree. That helps clarify how virus-like genetic elements have been maintained and diversified in animal genomes, while the study does not determine the exact time or mechanism of the original envelope-gene acquisition.

Evidence and caveats

The evidence comes from systematic searches of animal genome sequences, together with phylogenetic comparisons and analyses of predicted protein structures. These methods can reveal shared evolutionary histories and patterns of divergence, but the proposed Precambrian origin is an inference rather than a direct observation of the original acquisition. The abstract does not give the number of genomes or species examined, so the breadth of sampling and how broadly the result applies cannot be assessed from the available information.

An in-ear sensor recorded brain signals like nearby scalp electrodes

Researchers tested a flexible dry in-ear EEG sensor in 15 healthy adults and compared its recordings with standard scalp electrodes. The ear sensor recorded brain responses that closely resembled signals from a nearby temporal scalp site, particularly during auditory tasks.

16 hours ago·2 views

Biology

Pseudomonas biofilms spread more pyocyanin in lung tissue than on lab material

A study used chemical imaging to compare Pseudomonas aeruginosa biofilms grown on a laboratory surface and on mouse lung tissue. Biofilms on lung explants showed greater production and deeper tissue penetration of pyocyanin, a phenazine involved in biofilm activity and host interactions.

1 day ago·8 views

Biology

Some soil bacteria helped maize grow under greenhouse drought

Certain Streptomyces bacteria improved maize growth when plants were grown with limited water in a greenhouse experiment. The effects varied among the four bacterial isolates, and further testing is needed before they can be considered for field use.

1 day ago·36 views