DNA Ladders

The ultimate event in the apoptotic process is the activation of endonucleases cutting DNA in fragments of 50 kB and, later, in smaller fragments, responsible for the appearance of the classical DNA laddering on... 

One of the first reports showing that DAG attenuates ceramide induced apoptosis used two human myeloid leukemia cell lines, namely HL-60 and U937. Exposure of HL-60 and U937 cells to SMase or lOpM ceU-permeable ceramides for 6 h resulted in DNA-laddering, a typical hallmark of apoptosis. This could be aboUshed by di-octanoylglycerol, a cell permeable... 

In one of the wells, load 1.5 pL of 100-bp DNA ladder for tracking yonr target fragments and for the estimation of the molecular weight of the bands. 

Fig. 8 Topview of AFM images of different dsDNA topologies on amino-terminated mica a linear 2,-DNA (48.5 kbp), b non-twisted circular DNA plasmids (3.2 kbp), c circular su-percoiled DNA with twists and writhes due to internal supercoiling (supercoiled DNA ladder 2-16khp) [48]. Reprinted with permission...

Nonrandom mono- and oligonucleosomal length, fragmentation of DNA (ladder pattern after agarose gel eletrophoresis)... 

Fig. 6. Apoptotic DNA ladder pattern of eosinophils treated with dexamethasone (Dexa, 2 (xM) for 18 h (Zl). DNA was extracted from cells with ethanol (P4) and electrophoresed on 1% agarose gel in 1 X TAE (Tris acetate-EDTA) buffer (pH 8.0). After electrophoresis, the gel was soaked in 1 x TAE buffer containing 0.5 /tg/ml ethidium bromide, and DNA was visualized by an ultraviolet illuminator. Reproduced with permission from Zhang, J. R, Wong, C. K., Lam, C. W. K., Ho, C. Y., and Hjelm, N. M., Biochemical assessment of apoptosis. Chinese J. Lab. Med. Clin. Sci. 1, 27-28 (2000).

DNA fragmentation 4.8 Apoptotic DNA ladder assay TUNEL assay... 

The GSTPl exon 5 polymorphism, a 100 bp marker (100 bp DNA ladder MBI Fermentas) was used as a size standard for each gel line. The gel was monitorized using a visualizing system (Vilber Lourmat, France). 

DNA molecular weight marker (DNA ladder) a solution of DNA fragments in the 50-3000 base pair range. 

Load one sample into each of the sample wells in the following manner. Mix each 20 fiL of DNA plasmid and molecular weight standard marker (DNA ladder) with 10 fiL of gel-loading buffer and apply one 10-ju.L sample to each well. 

CEC was also applied to separate oligonucleotides. Here, an ion-pair reagent was used to enhance separation. Figure 6.27 shows the results of the separation of a DNA ladder (100-1000 bp) using conductivity detection. No separation occurred if the PMMA channel was not modified with a stationary phase [208]. 

Fraction collection of fragments from a 100-bp DNA ladder was also achieved in a PDMS chip [664] or a glass chip. In the latter example, a small reversed field was maintained in the separation column to halt or slow down later migrating DNA in order to assist collection of a DNA fraction [665]. In one report, a single peak from the IEF separation channel has been isolated and transferred to a subsequent channel by means of microfluidic valve control [449],... 

Biochemically, apoptosis is characterized by the internucleosomal degradation of chromosomal DNA to form a series of double-stranded fragments that are multiples of 180 200 base pairs in length. These fragments give a characteristic DNA ladder pattern on gel electrophoresis [91, 92] and can be detected by several cytochemical methods, the most extensively used being the terminal deoxynucleotidyl transferase (TdT)-mediated biotinylated dUTP nick end labeling (TUNEL) [93-95], The detection of ladder pattern and TUNEL positivity has been adopted as a marker of apoptosis. 

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