Researchers Report That More Than a Thousand Genes Harbor Among 218 Insect Species

Microbes and plants may have provided insects evolutionary edge hundreds of millions of years ago by transmitting genes to them via horizontal gene transfer.

Researchers reveal that more than 1,400 genes from bacteria, viruses, fungi, and plants were found in 218 butterfly species, including butterflies and moths, in a study published in the journal Cell on July 18.

According to the study, these genes may have been important for insect evolution since they allowed them to acquire favorable qualities in mating behavior, feeding, growth, and adaption to environmental changes.

Insects form a thousand genes of microbes

(Photo : Warren Umoh/Unsplash)

Horizontal gene transfer (HGT) between microorganisms is very prevalent. For example, bacteria employ this technique to spread antibiotic resistance genes between species, but scientists have increasingly focused on the phenomena in insects and microorganisms or plants, as per ScienceDaily.

Previous research has shown that HGT may have aided insect biodiversity, but no one understood how significant a role it plays in this process, according to lead author Xing-Xing Shen, an evolutionary biologist at Zhejiang University in Hangzhou, China.

Because there are so many high-quality insect genomes accessible for study, I felt it would be a good opportunity to look at how common HGT is in insects.

Shen's team at Zhejiang University began this effort alongside Antonis Rokas, an evolutionary biologist at Vanderbilt University, by collecting 218 high-quality insect genome samples from 11 of 19 species-rich insect orders.

They were able to create an evolutionary tree, detect out-of-place genes more typically found in non-animal genomes, and investigate what variables contribute to the fate of HGT in insects using the data.

According to Shen, there were HGT events wherever we looked. However, we don't know if these gene transfers are advantageous to insects, or even what most of these genes do, according to Shen.

He recruited the assistance of another specialist, Jianhua Huang, a Zhejiang University researcher who researches insect gene activities.

Shen came into my office with a list of almost 1,400 genes, and we had to figure out where to start, Huang explains.

The researchers opted to test the function of LOC105383139, the most common foreign gene with no known functions in insects.

This gene was horizontally transmitted into virtually all moths and butterflies from a donor in the bacterial genus Listeria, the researchers write in their paper, implying that it has been present in the genome since the common ancestor of moths and butterflies more than 300 million years ago.

They chose to remove this old gene from diamondback moths, which are a pest of broccoli and cabbage, and see what roles it has.

Shen came into my office with a list of almost 1,400 genes, and we had to figure out where to start, Huang explains. The researchers opted to test the function of LOC105383139, the most common foreign gene with no known functions in insects.

This gene was horizontally transmitted into virtually all moths and butterflies from a donor in the bacterial genus Listeria, the researchers write in their paper, implying that it has been present in the genome since the common ancestor of moths and butterflies more than 300 million years ago.

They chose to remove this old gene from diamondback moths, which are a pest of broccoli and cabbage, and see what roles it has.

Read more: Wooly Mammoth and Asian Elephants: Genetic Sequencing

Horizontal gene transfer

Horizontal gene transfer (HGT) is the non-sexual movement of genetic information between genomes. Incoming DNA or RNA can either replace or introduce new genes into a genome.

HGT in eukaryotes has been overshadowed by its frequency in bacterial genomes, yet a considerable number of eukaryotic examples have been reported.

Its influence varies by lineage, and many of the lineages most impacted by HGT are the least investigated at the genome level (for example, protists), therefore the relevance of HGT is likely to grow as databases grow.

Endosymbiosis has a long history in eukaryotic evolution.

Many genes were given to the nucleus by endosymbiotic organelles such as mitochondria and plastids, and further endosymbioses in plastid evolution allowed genes to transfer across eukaryotes.

Other persistent endosymbionts, such as Wolbachia, are now recognized as a substantial source of DNA in their hosts' nuclei.

HGT without symbiosis is also prevalent; the majority of recorded occurrences include bacterium genes being present in the nucleus.

Their prominence may be due to the fact that they are more visible than genes from other eukaryotes, yet bacteria may be the primary source of new genes due to their quantity.

Related article: A Better Understanding of DNA Sequencing