Design and connection of robust genetic circuits.

Phenotypic robustness is a highly sought after goal for synthetic biology. There are many well-studied examples of robust systems in biology, and for the advancement of synthetic biology, particularly in performance-critical applications, fundamental understanding of how robustness is both achieved and maintained is very important. A synthetic circuit may fail to behave as expected for a multitude of reasons, and since many of these failures are difficult to predict a priori, a better understanding of a circuit's behavior as well as its possible failures are needed.

Structure of long telomeric RNA transcripts: the G-rich RNA forms a compact repeating structure containing G-quartets.

Recent studies have identified RNA transcripts arising from mammalian telomeres with the transcript of the C-rich strand (r(5'-UUAGGG-3')(n)) being much more abundant than transcripts of the G-rich strand. Here we used transmission electron microscopy, CD, and nuclease digestion to investigate the structure of approximately 640-nucleotide (nt) RNA transcripts of the C-rich and G-rich strands of mammalian telomeric DNA. The CD spectrum of the C-rich RNA in low salt (10 mm KCl) or high salt (100 mm KCl) was typical of mixed sequence RNA, whereas the CD spectrum for the G-rich RNA differed with changes characteristic of parallel G-quadruplexes at the higher salt concentration.

Adsorption-induced scission of carbon-carbon bonds.

Covalent carbon-carbon bonds are hard to break. Their strength is evident in the hardness of diamonds and tensile strength of polymeric fibres; on the single-molecule level, it manifests itself in the need for forces of several nanonewtons to extend and mechanically rupture one bond. Such forces have been generated using extensional flow, ultrasonic irradiation, receding meniscus and by directly stretching a single molecule with nanoprobes.