Northern Blots
Northern blot analyses were carried out for mRNAs of some photogenes；these confirmed the results of the dot blot assays.Equal amounts of total leaf RNA were separated electrophoretically by size on agarose gels.The denatured RNA transcripts were transferred to Gene Screen and hybridized with 32P-labeled nick translated DNA probes for transcripts of rcL，ps2B，r16，ps1Al，and pslA2.The results of autoradiography as shown in Figure 3.The major transcripts ofrcL（1.6 plus 1.8 kb）and ps2B（1.2 kb）increased remarkably upon R irradiation.This increase was reversed if FR treatment followed exposure to R.The same is true for ps1Al and pslA2 whose major transcripts are 3.3 kb，1.7 kb and 3.7 kb，2.2 kb，1.75 kb，respectively.However，r16 showed a relatively stable transcript（1.54 kb）level after illumination with R.
Figure 3 Northem hybridization of maize RNA with cloned labeled probes for plastid genes.Equal aliquots（15 μg）of glyoxylated RNA from dark-grown（d）maize leaves or from leaves of plants subjected to treatment with R，FR，or R/FR were fractionated electrophoretically on 1.2%agarose gels，transferred to Gene Screen，and hybridized with 32 P-labeled probes（see Table 1）for rcL（a），ps2B（b），ps1A1（c），ps1A2（d），r16（e）.Four treatments（DR，FR，R/FR）have the same patterns and same intensities of rRNA onthe gels.The ethidium bromide-stained gels are shown in the left-hand panels corresponding to each probe.The locations of cytoplasmic 25S and 18S rRNAs，plastid 16S rRNA，and‘23S’rRNA breakdown products which are used as mol wt markers are indicated on the gels.The sizes of RNAs are indicated by numerals（kb）(https://www.daowen.com)
