Y Scolnik | PubMed Health

PubMed2001

Scanning force microscopy in the applied biological sciences.

Fifteen years after its invention, the scanning force microscope (SFM) is rooted deep in the biological sciences. Here we discuss the use of SFM in biotechnology and biomedical research. The spectrum of applications reviewed includes imaging, force spectroscopy and mapping, as well as sensor applications. It is our hope that this review will be useful for researchers considering the use of SFM in their studies but are uncertain about its scope of capabilities. For the benefit of readers unfamiliar with SFM technology, the fundamentals of SFM imaging and force measurement are also briefly introduced.

Journal Article↗

PubMed1993

On the metastability of left-handed DNA motifs.

Alternating purine-pyrimidine DNA sequences such as poly [d(C-G)] or poly[d(m5C-G)] undergo a cooperative, salt-induced structural transition from a right-handed B conformation, which prevails at relatively low ionic strength, into a left-handed Z form, generally believed to be stabilized by high salt concentrations. We report here that upon a monotonous increase of the ionic strength, the well-established B to Z transition is followed by a second, hitherto unobserved conformational change leading from Z-DNA back into a right-handed B-like form. This observation indicates that, in contrast with the current convention, the Z motif represents an unstable configuration relative to the B form at both low and high salt concentrations and that the occurrence of a left-handed DNA structure, presently depicted as a step function of the ionic strength, should rather be treated in terms of a pulse. The reported transition underscores the inherent metastability of the Z configuration, and indicates, consequently, that this motif is ideally suited to act as a structural regulatory element, as such an element should be endowed with a large susceptibility to cellular parameters.

Base Sequence↗