New England Biolabs, N3239S, Quick-Load® 1 kb Extend DNA Ladder

Related Categories DNA Markers & Ladders Applications DNA Analysis Specification Bases Fragment Mass (ng) bp 1 30 48,502 2a 15 20,066 2b 15 19,871 3 45 15,000 4 33 10,002 5 33 8,001 6 40 6,001 7 33 5,001 8 26 4,001 9 100 3,001 10 37 2,000 11 27 1,500 12 33 1,000 13a 18 517 13b 17 500 Preparation The double-stranded DNA is digested to completion with appropriate restriction enzymes, phenol extracted and equilibrated in storage buffer. Effective Size Range 500bp to 48,502bp Storage Buffer 2.5% Ficoll®-400 11 mM EDTA 3.3 mM Tris-HCl 0.017% SDS 0.015% bromophenol blue pH 8 @ 25°C FAQ Q: Why are the DNA ladders showing up on my Southern blot? What is the sequence or composition of the ladder bands? A: This phenomenon has been observed in a variety of labs, and, while we do not have an absolute explanation, there are 2 likely sources for the seemingly unlikely hybridization of the user’s probe to the ladder’s DNA. One is that, if the probe itself was generated from a pUC or pBR based plasmid, there may be a low level of plasmid contamination in the probe that is hybridizing to the ladder’s bands, most of which have pUC-like sequences in them.Alternately, there may just be some random, low specificity homology between the probe and some segment of the ladder fragments. The bands consist entirely of DNA derived from either pUC or Adenovirus 2 DNA, which is used as filler DNA to generate plasmids of the right size for the markers. Because the molar amount of DNA in the ladder bands is frequently in great excess compared to the DNA being probed, even a relatively low homology can still result in enough incorporation of probe to give a readily detectable signal. Q: Why is my DNA Ladder floating out the wells? Why are there no bands visible in my DNA ladder gel lane? A: If the ready-to-load DNA Ladder or the 6X Loading Dye supplied with the ladder has been frozen at any time, the Ficoll will form a density gradient in the vial upon thawing. Any volume pipetted from the top of the vial will contain only a small amount of density agent and will float out of the wells. To prevent this, mix well upon receipt and before use.