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Total poly(A)-containing RNA prepared from hen oviduct and centrifuged on an isokinetic sucrose gradient displays four peaks of optical absorbance. These have been identified by translation in vitro as lysozyme, ovomucoid, ovalbumin, and conalbumin mRNAs. Isolation and recentrifugation of the peaks results in partial purification of each mRNA. Molecular weights have been determined for the mRNAs on agarose gels containing 20 mM methylmercury hydroxide. Each mRNA possesses a number of apparently untranslated nucleotides ranging from approximately 900 bases for ovalbumin and conalbumin mRNAs to 200 bases for ovomucoid and lysozyme mRNAs. The mRNAs have been copied with avian myeloblastosis virus reverse transcriptase. Each mRNA with the exception of conalbumin gives rise to a high proportion of full length cDNA. Several parameters previously reported to influence the size distribution of cDNA had no effect on the length of cDNA made from any mRNA fraction. The proportion of full length copy does depend on the reverse transcriptase lot.
Buell et al. (Sat,) studied this question.