Abstract
Ovaries of the amphibian Triturus viridescens contain a considerable amount of 7 to 12 S RNA which fractionates with poly(A)+ RNA on oligo(dT)-cellulose column chromatography and directs the synthesis of all five classes of histones in a wheat germ cell-free system. The polyadenylate tracts associated with this 7 to 12 S poly (A)+ RNA are heterogeneous in length, ranging from approximately 60 to 120 nucleotides. Partially purified subfractions of histone mRNA templates were isolated from this RNA by preparative polyacrylamide gel electrophoresis. The correlation between the poly(A) content, the template activity in vitro, and the cell-free products encoded by these RNA subfractions suggests that Triturus ovary RNA contains poly(A)+ histone mRNA. The 7 to 12 S poly(A)+ RNA, but not 7 to 12 S poly(A)- RNA, is an effective template for the avian myeloblastosis virus reverse transcriptase-directed synthesis of complementary DNA (cDNA) in the presence of oligo(dT) primer. In the absence of primer, virtually no cDNA is synthesized. When cDNA complementary to 7 to 12 S poly(A)+ RNA is hybridized in situ to Drosophila melanogaster polytene chromosome preparations. cDNA hybrids are found primarily in the region 39D-E, the locus of the histone genes in Drosophila. This cDNA also hybridizes to the sea urchin histone gene sequences contained in the chimeric bacterial plasmids pSp2 and pSp17. These results provide strong evidence for the reality of polyadenylated histone mRNA in Triturus ovary.
Highlights
Ovaries of the amphibian Triturus viridescens contain a considerable amount of 7 to 12 S RNA which fractionates with poly(A)+ RNA on oligo(dT)-cellulose column chromatography and directs the synthesis of all five classes of histones in a wheat germ cell-free system
In an attempt to determine more directly whether the histone mRNA sequences fractionating with poly(A)+ RNA are polyadenylated, we have isolated a 7 to 12 S poly(A)+ RNA
Some oligo(A) sequences are detected in unfractionated ovary RNA, the 7 to 12 S poly(A)+ preparation has no detectable oligo(A)
Summary
Ovaries of the amphibian Triturus viridescens contain a considerable amount of 7 to 12 S RNA which fractionates with poly(A)+ RNA on oligo(dT)-cellulose column chromatography and directs the synthesis of all five classes of histones in a wheat germ cell-free system. When cDNA complementary to 7 to 12 S poly(A)+ RNA is hybridized in situ to Drosophila melanogaster polytene chromosome preparations, cDNA hybrids are found primarily in the region 39D-E, the locus of the histone genes in Drosophila This cDNA hybridizes to the sea urchin histone gene sequences contained in the chimeric bacterial plasmids pSp2 and pSpl. This cDNA hybridizes to the sea urchin histone gene sequences contained in the chimeric bacterial plasmids pSp2 and pSpl7 These results provide strong evidence for the reality of polyadenylated histone mRNA in Triturus ovary. Previous experiments [1, 2] have not completely ruled out the possibility that the histone mRNA templates present in amphibian ovary poly(A)+ RNA preparations could be poly(A)- histone mRNA contaminants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
