Techniques

Magnetic Tweezers of all flavors

Magnetic tweezers are a single-molecule technique with wide applicability in the study of processive motor proteins and other enzymes, yielding insight into their kinetics and mechanochemistry. In addition to the conventional magnetic tweezers that can apply force and torque to biological molecules, our laboratory has expanded the different types of magnetic tweezers available so that they can also be used to measure torque or twist.

Fluorescence microscopy

Fluorescence microscopy is used to visualise DNA and/or proteins that have been tagged with fluroescent dyes. We employ them in two contexts: first, in vitro with purified proteins tagged with organic fluorescent dyes, allowing us to image the mechanics of DNA replication; and second, in vivo using genetically engineered proteins linked to GFP derivates, allowing us to image the mechanics of DNA replication as they occur in the context of bacterial cells.

Optical torque wrench

dna3Optical tweezers involved focus laser beams that can trap beads and are highly useful in single-molecule biophysics experiments. We employ a torque-sensitive variant of the optical tweezers, denoted the optical torque wrench, that makes use of birefringent particles to control and measure of torque in biological systems.

Microfluidics

microfluidic_device
The use of microfluidics in biological research has gained much popularity in recent years. We fabricate a versatile device with growth channels, capable of being used to study different bacterial species in a high-thoughput manner. In its design, cells are confined in the growth channels oriented perpendicularly to a trench through which growth medium is flown. This allows us to study a large number of cells that inherit the same cell pole over multiple generations. Cells are immobilized, in the absence of chemical fixation, at the far end of such a growth channel (ca. 25 µm in length). The length of the growth channels is chosen so as to ensure sufficient supply of nutrients to the bacteria by diffusion, which allows us to simultaneously study numerous different cells for extensive periods of time.

Genetic engineering

For live-cell imaging, we perform genetic engineering in order to introduce genetically-encoded fluorophores into the bacterial chromosome.