The intrinsic viscosity of linear DNA

Abstract

We measured the intrinsic viscosity of very small synthetic DNA molecules, of 20-395 base pairs, and incorporated them in a nearly complete picture for the whole span of molecular weights reported in the literature to date. A major transition is observed at M approximately 2 × 10(6) . It is found that in the range of approximately 7 × 10(3) ≤ M ≤ 2 × 10(6) , the intrinsic viscosity scales as [η] approximately M(1.05) , suggesting that short DNA chains are not as rigid as generally thought. The corresponding scaling for the range of 2 × 10(6) ≤ M ≤ 8 × 10(10) is [η] approximately M(0.69) . A comparison of our results with existing equations, for much narrower data distributions, is made, and the agreement is very satisfactory considering the huge range of data analyzed here. Experimental concerns such as the effect of ionic strength, polydispersity, temperature, and shear rate are discussed in detail. Some issues concerning the Huggins coefficient, polymer chain stiffness, and the relationship between the Mark-Houwink constants K, α are also presented; it is found that log K = 1.156 - 6.19α.

A micro-liter viscosity and density sensor for the rheological characterization of DNA solutions in the kilo-hertz range

“…The concentration ranges of the solutions used here are outlined in Table 2 along with the intrinsic viscosity and The concentration range of the short strands is below c * for all solutions, whereas it is above for the long strands for all samples except the one with the lowest concentration. 3 Results and discussion…”

If Systems Approach is the Way Forward, What can the Ayurvedic Theory of <i>Tridosha</i> Teach Us?

“…twenty factors (Vimśati guna) 15 : (1,2) heavy (guru) and light (laghu); (3,4) cold (sheeta) and hot (ushna); (5,6) oiliness (snigdha), dryness (ruksha); (7,8) slow/dull (manda), sharp (tikshna); (9,10) immobility (sthira), mobility (sara); (11,12) soft (mrudu), hard (kathina); (13,14) adhesive/sticky (pichchila), non-slimy/non-adhesive (vishada); (15,16) smooth (shlakshna), rough (khara); (17,18) minuteness (sukshma), gross (sthula); (19,20) viscidity (sandra), diffusivity/fluidity (drava). These properties at the opposite ends of a continuum are inherent to material bodies and used in ayurveda to understand the human system.…”

“…This indicates the relevance of dryness in biology. Interestingly, many of these properties such as dryness, viscosity and adhesion used in ayurveda are increasingly being studied for their physiological roles and clinical relevance [19][20][21][22][23][24][25][26][27][28][29][30] . Just as the functions associated with VPK, these parameters (V1-V7, P1-P7, K1-K7) also exist at all levels of biological organization.…”

“…Other parameters such as lubrication (K3) and viscosity (K4) also have clinical implications. As working examples, consider the following: viscosity of cellular cytoplasm acting on the hydrodynamic forces and affecting macromolecular as well as cellular motion leading to functional changes; viscosity of blood affecting bloodflow; viscoelasticity of synovial fluid in joints influencing movement at the system level 19,20,30 .…”

A Viscometric Chip for DNA Analysis

“…The buffer composition was 10 mM KCl in 50 mM Tris-HCl, pH 7.5. The 110 bp sequence was as described by Tsortos et al [3]. Each series was measured three times at 23°C.…”