Northern blot

The emission yield from the horseradish peroxidase (HRP)-catalyzed luminol oxidations can be kicreased as much as a thousandfold upon addition of substituted phenols, eg, -iodophenol, -phenylphenol, or 6-hydroxybenzothiazole (119). Enhanced chemiluminescence, as this phenomenon is termed, has been the basis for several very sensitive immunometric assays that surpass the sensitivity of radioassay (120) techniques and has also been developed for detection of nucleic acid probes ia dot-slot. Southern, and Northern blot formats (121). 

The northern blotting technique is similar to the Southern blotting technique with the exception that northern blots detect specific sequences of RNA, not DNA. 

Northern blot A method for transferring RNA from an agarose gel to a nitrocellulose filter, on which the RNA can be detected by a suitable probe. 

Signal The end product observed when a specific sequence of DNA or RNA is detected by autoradiography or some other method. Hybridization with a complementary radioactive polynucleotide (eg, by Southern or Northern blotting) is commonly used to generate the signal. 

Detection of expression of mRNAs in tissues by Northern blotting using one or more fragments of the gene as a probe The mRNA should be expressed in affected tissues. 

B. Northern blot analysis of total RNA extracted from hypocotyls of P. vulgaris and hybridised to a radioactive pg/p-specific probe. 

Northern blot analysis revealed that expression of NHE-1 is tissue-specific with highest transcript abundance in stomach and minimal levels in liver and skeletal muscle. Moreover, there is physiological evidence that certain segments of the nephron lack a basolateral Na /H" exchanger [76]. Using RT-PCR, Krapf and Solioz [77] observed that NHE-1 transcripts are not detectable in SI and S2 segments of superficial nephrons. 

With regard to the potential function of Raf-1 in mammalian germ cells, the testis is a site of abundant expression of c-ra/-l mRNAs. Northern blot and in situ hybridization analysis has shown that although c-ra/-l is expressed most abundantly in early pachytene spermatocytes, some transcripts were also detected in germ cells from type A and B spermatogonia through to the round spermatid stage (Wolfes et al., 1989 Wadewitz et al., 1993). 

Fig. 14.5. Composite of Northern blots prepared with RNA isolated from different A. suum larval stages and adult tissues and probed with A. suum cDNAs specific for E1al (Johnson etal., 1992) E1all (Johnson etal., 1992) ...

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