For many aphids, EBF is the principal constituent of the aphid alarm pheromone, and the constitutive production of EBF by plants could hold promise in the control of specific aphid pests

TLS Online TPP Program

#Id: 6892

#Unit 3. Fundamental Processes

To modify DNA at a new position requires the action of a de novo methyltransferase, which recognizes DNA by virtue of a specific sequence. It acts only on unmethylated DNA to add a methyl group to one strand.

TLS Online TPP Program

#Id: 6893

#Unit 3. Fundamental Processes

There are two de novo methyltransferases (Dnmt3A and Dnmt3B) in the mouse; they have different target sites, and both are essential for development.

TLS Online TPP Program

#Id: 6894

#Unit 3. Fundamental Processes

A maintenance methyltransferase acts constitutively only on hemimethylated sites to convert them to fully methylated sites. Its existence means that any methylated site is perpetuated after replication.  There is one maintenance methyltransferase (Dnmt1) in mice, and it is essential.

TLS Online TPP Program

#Id: 6895

#Unit 3. Fundamental Processes

UHRF1, that is important for the maintenance of methylation both locally and globally through its association with Dnmt1.

TLS Online TPP Program

#Id: 6896

#Unit 3. Fundamental Processes

UHRF1 also interacts with methylated histone H3, which connects the maintenance of DNA methylation with the stabilization of heterochromatin structure

TLS Online TPP Program

#Id: 6897

#Unit 3. Fundamental Processes

HP1 is recruited to regions in which histone H3 has been methylated at lysine 9, a modification involved in heterochromatin formation. It turns out that HP1 can also interact with Dnmt1, which can promote DNA methylation in the vicinity of HP1 binding. Furthermore, Dnmt1 can directly interact with the methyltransferase responsible for H3K9 methylation, creating a positive feedback loop to ensure continued DNA and histone methylation.