Image of the Day: The Metamorphosis Gene

A gene that is important for helping caterpillars transform into butterflies is also key for the maturation of insects like grasshoppers, which undergo incomplete metamorphosis, a new study finds.

The finding is the first molecular evidence that the nymphal stage in lower insects is the same as the pupal, or chrysalis, stage of advanced insects such as butterflies.

The study, led by Deniz Erezyilmaz at the University of Washington, found that the so-called "broad" gene found that direct-developing insects is expressed during the nymphal stage. If broad is suppressed, the nymph simply repeats the appearance from its previous phase but continues to show normal growth. The insect becomes an adult, but adult structures such as wings are severely undersized. This would be the same as a human baby growing to 6 feet tall but still having infant body proportions.

The image above shows an insect in the fourth nymphal stage of development (Figure A). Usually, an insect would progress to the fifth development stage (Figure B), but in an insect whose broad gene is suppressed in the first half of the fourth stage, the nymph moves to the fifth stage but keeps pigmentation patterns and other characteristics of the fourth stage (Figure C).

The finding was detailed in a March issue of the journal for the Proceedings of the National Academy of Sciences.