In this, the first of three papers, we present the sequence of the ribosomal RNA (rRNA) genes of Drosophila melanogaster. The gene regions of D. melanogaster rDNA encode four individual rRNAs: 18S (1,995 nt), 5.8S (123 nt), 2S (30 nt), and 28S (3,945 nt). The ribosomal DNA (rDNA) repeat of D. melanogaster is AT rich (65.9% overall), with the spacers being particularly AT rich. Analysis of DNA s...

The DNA sequence of the intragenic region of the rat 45S ribosomal RNA precursor was determined. This sequence contains 2282 nucleotides and extends from the conserved EcoR I site near the 3' terminus of 18S rRNA to 69 nucleotides downstream of the 5' terminus of 28S rRNA. The sequences corresponding to 18S and 5.8S rRNA were identified by comparison with previously published data. The 5' termi...

Gyrodactylus colisai n. sp., found on body surface of fish, Colisa fasciata collected at Hastinapur, Meerut, India, is described. New species is characterized morphologically in having a club shaped head organ and absence of ventral bar membrane. 28S ribosomal DNA of this worm has also been sequenced for molecular characterization and found to be distinct from all the species of this genus, seq...

The set of "expansion segments" of any eukaryotic 26S/28S ribosomal RNA (rRNA) gene is responsible for the bulk of the difference in length between the prokaryotic 23S rRNA gene and the eukaryotic 26S/28S rRNA gene. The expansion segments are also responsible for interspecific fluctuations in length during eukaryotic evolution. They show a consistent bias in base composition in any species; for...

A large DNA-containing body is present in addition to the chromosomes in oocytes of the house cricket Acheta domesticus. Large masses of nucleolar material accumulate at the periphery of the DNA body during the diplotene stage of meiotic prophase I. RNA-DNA hybridization analysis demonstrates that the genes which code for 18S and 28S ribosomal RNA are amplified in the ovary. In situ hybridizati...

Eco-RI-A fragments of the human ribosomal RNA gene family from two types of tissue and three individuals were cloned in lambda vectors and compared by restriction enzyme digestion and electron microscopy. The EcoRI fragment A contains (i) 0.2 kb of the 3' end of the 18S rDNA, (ii) 2.5 kb of internal transcribed spacer and the 5.8S rDNA, and (iii) 4.6 kb of the 28S rDNA gene. All of the six clon...

The 5S RNA genes of Drosophila melanogaster in either an isogenic wildtype or a multiply inverted (SM1) chromosome 2 increase their multiplicity when opposite a deficiency for the 5S gene site. This is analogous to the compensation phenomenon previously described for the 18S and 28S ribosomal RNA genes of the X chromosome nucleolus organizer region. Molecular hybridization of 5S RNA to DNA cont...

Histones are the major protein component of chromatin structure. The histone family is made up of a quintet of proteins, four core histones (H2A, H2B, H3 & H4) and the linker histones (H1). Spacers are found between the coding regions. Among insects this quintet of genes is usually clustered and the clusters are tandemly repeated. Ribosomal DNA contains a cluster of the rRNA sequences 18S, 5.8S...

RNA from noninfectious virions produced by two established clonal lines of sarcoma positive-leukemia negative (S+L-)-transformed 3T3 cells has been characterized. RNA from virions or nucleoids of S+L--(C243) cells consisted of three to four sizes: +/-44 S (6%), 28 S (17%), 18 S (38%), and <18 S (39%). 28S virion RNA contained some virus-specific information demonstrable by RNA.DNA hybridization...

An Eco RI 6.6 kb DNA fragment containing the 3'-end of 28S ribosomal RNA gene of the mouse was detected by Southern blot hybridization, and cloned in a x-phage vector. The site of transcription termination and the processed 3'-end of 28S RNA were determined on the cloned fragment and the surrounding nucleotide sequence determined. The 3'-terminal nucleotides of mouse 28S RNA are similar to thos...