Small and Magical

By TANG YUANKAI

Small and Magical

By TANG YUANKAI

Ant genome study offers promising evidence in medical and anti-aging research

While children often love observing ants happily for hours, grown-ups are more likely to ignore these small creatures. Some scientists, however, show greater interest in ants than children do. One of them is Zhang Guojie, Associate Director of the Bioinformatics Center and Leader of Genome Projects in BGI. BGI is China’s largest genome and bioinformatics analysis center in Shenzhen, in south China’s Guangdong Province.

In September, Zhang resumed his cooperation with researchers at the University of Copenhagen to study the genome ofAcromyrmex echinatior, commonly known as leaf-cutting ants.

Zhang started sequencing ants’ genomes in 2009 as part of a program involving similar sequencing of more than 100 animals and plants. Half of the projects are fi nished or close to finishing, and many research results have been published. For instance, the results of panda and cucumber genome sequencing have been published in prestigious academic journals such asNatureandSciencemagazines.These fi ndings have provided researchers sufficient data for studying interesting biological phenomenons among ant species.

Anti-aging secrets

In scientists’ eyes, the ant has the most specifically divided social division of labor.In an ant colony, there are the queen, soldiers,workers and female ants, all with respective responsibilities and divisions of labor in their group.

Zhang’s team has discovered, compared to other ants, the leaf-cutting ant has special social behaviors due to special genes. The genome sequencing and analysis results of leaf-cutting ants by Chinese and Danish researchers were published online on June 30 inGenome Research, an internationally famous academic journal in the fi eld.

“These research results will lay an important foundations for studying social behavior in the context of genetics by informing people about the connection between the social hierarchy and genomes of leaf-cutting ants,” said Zhang.

Ant species are not only vastly different in appearance and behavior, but also in longevity. For instance, the queen may live for nearly 10 years while worker ants can only live for one to two months.

“By analyzing their genomes, we hope to fi nd the reason for different longevity of ants,” said Zhang.

For this reason, the Shenzhen BGI Genomics and Bioinformatics Analysis Center cooperated with the New York University, Arizona State University and University of Pennsylvania on the study of the genomes of two other ant species—CamponotusandHarpegnathos saltator. By comparing their genomes and gene expressions at different life phases, they hoped to find out how genetics influences the aging process and social behavior of humans. As a result, they have discovered genes related to ants’ aging process, nerve function and chemical communications. The results were published in Science in August, 2010.

MULTIPLE ANTS: Two Camponotus ants (left) seek food along with a weevil in a rainforest in south China’s Hainan Province. The province is abundant in various kinds of ants

“These results have offered us a good model for further study on behavior and longevity control of human beings,” said Zhang.

They found, among others, the enzyme telomerase is critical in deferring senility.

“When studying ants, we found telomerase has very low activity in ordinary worker ants, which is the reason for their very short life. But in worker ants ofHarpegnathos saltator, which are able to mate, telomerase has very high activity. The high activity of telomerase accounts for their relatively longer life,”said Zhang. “This shows that telomerase plays a key role in determining the longevity of different species of ants.”

“If telomerase activity is greater, the length of the telomere (either free end of a eukaryotic chromosome), which keeps the sticky ends of chromosomes from clumping together, will be greater, and cellular aging will be deferred,” said Zhang.

“In the future, we want to build models with ants to thoroughly analyze their different division of labor, behavior and longevity,” said Zhang. “By fi nding out the key genes that lead to those differences, we can offer critical clues and evidence to understand the longevity and behavior of human beings.”

Helpful in medicine

Ants haven’t just become recently popular. In traditional Chinese medicine,ants have been used for treating diseases for thousands of years. There is a multitude of species and they can be easily collected. For instance, ants have been used in curing rheumatoid arthritis and boosting immunity. Ants have also been a special food in many parts of China since ancient times.

And probing into ant genomes can also help develop new antibiotics and improve the effectiveness of older ones.

Surprisingly, ants have used antibiotics for a much longer time than human beings, for as long as 50 million years. This raises questions:Why are antibiotics still effective in the ants after such a long period of time and why has no resistance developed in their bodies?

Human beings have only used antibiotics for 50 years. They are already less effective in treating diseases because strains of bacteria in the human body become resistant to antibiotics due to improper use and abuse of antibiotics. While researchers in this area are developing new antibiotics or finding ways to make older ones effective again, some scientists have counted on ants for solutions,if they have really evolved sufficiently to prevent decreases in the effectiveness of antibiotics.