ABSTRACT
RNA interference (RNAi) has become an important tool to study and utilize gene silencing by introducing short interfering RNA (siRNA). In order to predict the most efficient siRNAs, a new software tool, RNA Workbench (RNAWB), has been designed and is freely available (after registration) on http://www.rnaworkbench.com. In addition to the standard selection rules, RNAWB includes the possibility of statistical analyses of the applied selection rules (criteria). The role of RNA secondary structures in the RNA interference process as well as the application of sequence rules are discussed to show the applicability of the software.
Subject(s)
Algorithms , Gene Targeting/methods , RNA Interference , RNA, Small Interfering/genetics , Sequence Alignment/methods , Sequence Analysis, RNA/methods , Software , Base Sequence , Molecular Sequence DataABSTRACT
RNA interference is a powerful tool for gene silencing, which is mediated by introducing siRNA. In the present study, statistical analyses of published siRNA selection criteria, the interpretation of some criteria and systematic searching for new criteria have been carried out for CGB siRNA and siRecords databases. The results of the analyses are as follows: (i) Our study supports the two-state model of the RNA-induced silencing complex (RISC). (ii) Stable 5'-S ends of a siRNA sequence, higher stability of the whole siRNA, and low breaking energy of siRNA duplex occurs in effective siRNA sequences. Also low internal stability of the 5'-AS terminus is preferred. (iii) Secondary structure can be successfully used as an RNAi selection criterion. (iv) Several published sequence criteria have been confirmed and also new criteria have been developed. (v) Also a Target Patterns criterion, which is comparable or better than the best known criteria, has been created.
Subject(s)
Gene Silencing , Models, Genetic , RNA, Small Interfering/genetics , Sequence Analysis, RNA/methods , Base Sequence , Data Interpretation, Statistical , Models, Statistical , Molecular Sequence DataABSTRACT
Water amid the restricted space of crowded biological macromolecules and at membrane interfaces is essential for cell function, though the structure and function of this "biological water" itself remains poorly defined. The force required to remove strongly bound water is referred to as the hydration force and due to its widespread importance, it has been studied in numerous systems. Here, by using a highly sensitive dynamic atomic force microscope technique in conjunction with a carbon nanotube probe, we reveal a hydration force with an oscillatory profile that reflects the removal of up to five structured water layers from between the probe and biological membrane surface. Further, we find that the hydration force can be modified by changing the membrane fluidity. For 1,2-dipalmitoyl-sn-glycero-3-phosphocholine gel (Lbeta) phase bilayers, each oscillation in the force profile indicates the force required to displace a single layer of water molecules from between the probe and bilayer. In contrast, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine fluid (Lalpha) phase bilayers at 60 degrees C and 1,2-dioleoyl-sn-glycero-3-phosphocholine fluid (Lalpha) phase bilayers at 24 degrees C seriously disrupt the molecular ordering of the water and result predominantly in a monotonic force profile.
