The Radiant Transmittance of Tandem Arrays of Filters

1972 ◽  
Vol 19 (10) ◽  
pp. 853-864 ◽  
Author(s):  
P. Baumeister ◽  
R. Hahn ◽  
D. Harrison
Keyword(s):  
Tandem Arrays

Repeat arrays in cellular DNA related to the Epstein-Barr virus IR3 repeat

1985 ◽  
Vol 5 (3) ◽  
pp. 457-465
Author(s):  
M Heller ◽  
E Flemington ◽  
E Kieff ◽  
P Deininger
Keyword(s):  
Epstein Barr Virus ◽  
Tandem Repeats ◽  
Protein Domain ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Epstein Barr ◽  
Cellular Dna ◽  
The Relationship ◽  
Simple Sequence ◽  
Tandem Arrays

We isolated clones and determined the sequence of portions of mouse and human cellular DNA which cross-hybridize strongly with the IR3 repetitive region of Epstein-Barr virus. The sequences were found to be tandem arrays of a simple sequence based on the triplet GGA, very similar to the IR3 repeat. The cellular repeats have distinct differences from the viral repeat region, however, and their sequences do not appear capable of being translated into a purely glycine-plus-alanine protein domain like the portion of the Epstein-Barr nuclear antigen coded by IR3. Although the relationship between IR3 and the cellular repeats is left unclear, the cellular repeats have many interesting features. The tandem arrays are about 1 to several kilobases long, much shorter than satellite tandem repeats and larger than other interspersed, tandem repeats. Each of the repeats is a distinct variation, perhaps diverged from a common sequence, (GGA)n. This family is present in the genomes of all species tested and appears to be a ubiquitous feature of all higher eucaryotic genomes.

The two embryonic U1 small nuclear RNAs of Xenopus laevis are encoded by a major family of tandemly repeated genes

1984 ◽  
Vol 4 (12) ◽  
pp. 2580-2586
Author(s):  
E Lund ◽  
J E Dahlberg ◽  
D J Forbes
Keyword(s):  
Xenopus Laevis ◽  
Large Family ◽  
Distinct Species ◽  
Single Copy ◽  
Haploid Genome ◽  
Small Nuclear Rnas ◽  
Cell Embryo ◽  
Rna Genes ◽  
Repeated Genes ◽  
Tandem Arrays

We have identified a large family of U1 RNA genes in Xenopus laevis that encodes two distinct species of U1 RNA. These genes are expressed primarily at the onset of transcription in the 4,000-cell embryo (D. J. Forbes, M. W. Kirschner, D. Caput, J. E. Dahlberg, and E. Lund, Cell 38:681-689, 1984). The two types of embryonic U1 RNA genes are interspersed and are organized in large tandem arrays. The basic 1.9-kilobase repeating unit contains a single copy of each of the embryonic genes and is reiterated ca. 500-fold per haploid genome. This repetitive U1 DNA accounts for more than 90% of all U1 DNA in X. laevis. In addition to this major family, there exist several minor families of dispersed U1 RNA genes, which presumably encode the oocyte and somatic species of X. laevis U1 RNA. Although the embryonic genes are normally inactive in stage VI oocytes, they are expressed when cloned copies are injected into oocyte nuclei.

scholarly journals The Highly Repetitive Region of the Helicobacter pylori CagY Protein Comprises Tandem Arrays of an α-Helical Repeat Module

2008 ◽  
Vol 377 (3) ◽  
pp. 956-971 ◽  
Author(s):  
Robin M. Delahay ◽  
Graham D. Balkwill ◽  
Karen A. Bunting ◽  
Wayne Edwards ◽  
John C. Atherton ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Repetitive Region ◽  
Tandem Arrays

Repetitive sequences in the genome ofAnemone blanda: Identification of tandem arrays and of dispersed repeats

Chromosoma ◽  
1993 ◽  
Vol 102 (5) ◽  
pp. 312-324 ◽  
Author(s):  
Sylvia Hagemann ◽  
Brigitte Scheer ◽  
Dieter Schweizer
Keyword(s):  
Repetitive Sequences ◽  
Dispersed Repeats ◽  
Tandem Arrays

scholarly journals Long Tandem Arrays of Cassandra Retroelements and Their Role in Genome Dynamics in Plants

2020 ◽  
Vol 21 (8) ◽  
pp. 2931 ◽  
Author(s):  
Ruslan Kalendar ◽  
Olga Raskina ◽  
Alexander Belyayev ◽  
Alan H. Schulman
Keyword(s):  
Copy Number ◽  
5S Rdna ◽  
5S Rrna ◽  
Rrna Genes ◽  
Gene Copy ◽  
Rrna Gene ◽  
Long Terminal Repeats ◽  
5S Rrna Genes ◽  
Pol Iii ◽  
Tandem Arrays

Retrotransposable elements are widely distributed and diverse in eukaryotes. Their copy number increases through reverse-transcription-mediated propagation, while they can be lost through recombinational processes, generating genomic rearrangements. We previously identified extensive structurally uniform retrotransposon groups in which no member contains the gag, pol, or env internal domains. Because of the lack of protein-coding capacity, these groups are non-autonomous in replication, even if transcriptionally active. The Cassandra element belongs to the non-autonomous group called terminal-repeat retrotransposons in miniature (TRIM). It carries 5S RNA sequences with conserved RNA polymerase (pol) III promoters and terminators in its long terminal repeats (LTRs). Here, we identified multiple extended tandem arrays of Cassandra retrotransposons within different plant species, including ferns. At least 12 copies of repeated LTRs (as the tandem unit) and internal domain (as a spacer), giving a pattern that resembles the cellular 5S rRNA genes, were identified. A cytogenetic analysis revealed the specific chromosomal pattern of the Cassandra retrotransposon with prominent clustering at and around 5S rDNA loci. The secondary structure of the Cassandra retroelement RNA is predicted to form super-loops, in which the two LTRs are complementary to each other and can initiate local recombination, leading to the tandem arrays of Cassandra elements. The array structures are conserved for Cassandra retroelements of different species. We speculate that recombination events similar to those of 5S rRNA genes may explain the wide variation in Cassandra copy number. Likewise, the organization of 5S rRNA gene sequences is very variable in flowering plants; part of what is taken for 5S gene copy variation may be variation in Cassandra number. The role of the Cassandra 5S sequences remains to be established.

scholarly journals Transfection of mouse fibroblast cells with a promoterless herpes simplex virus thymidine kinase gene: number of integrated gene copies and structure of single and amplified gene sequences.

1985 ◽  
Vol 5 (2) ◽  
pp. 295-304 ◽  
Author(s):  
W Pülm ◽  
R Knippers
Keyword(s):  
Herpes Simplex Virus ◽  
Dna Replication ◽  
Herpes Simplex ◽  
Thymidine Kinase ◽  
Mouse Fibroblast ◽  
Copy Numbers ◽  
Gene Copies ◽  
Cell Clones ◽  
Simplex Virus ◽  
Tandem Arrays

Plasmids carrying the herpes simplex virus thymidine kinase (tk) gene were used to transfect thymidine kinase-deficient cells of the mouse fibroblast cell line LM(tk-). Individual cell clones were cultivated in selective hypoxanthine-aminopterin-thymidine medium to determine the number of integrated plasmid copies which was almost always in the range of one to three copies per genome. In contrast, cells transfected with plasmids carrying a promoterless "truncated" tk gene typically contained between 10 and 25 copies per genome. Surprisingly, when the truncated tk gene was transfected together with a simian virus 40 DNA segment, including its transcriptional enhancer, the number of integrated tk gene copies was always low, between one and three copies per genome. We have analyzed the genomic organization of integrated truncated tk genes by blot hybridization of restricted cellular DNA and concluded that integrated units of plasmid DNA molecules are arranged in tandem arrays which remain stable in most cases for many cell generations. In only 1 of ca. 20 cell clones did we observe a retraction and expansion of the number of integrated promoterless tk genes as a response to the removal or readdition of selective pressure. Surprisingly, the thymidine kinase activity determined in extracts from cells growing in selective hypoxanthine-aminopterin-thymidine medium (high numbers of integrated tk gene copies) was nearly the same as the enzymatic activity in cells growing in nonselective medium (low copy numbers). Moreover, Northern blots of polyadenylated RNA, extracted from cells growing under selective and nonselective conditions, showed that, in both cases, the major species of tk-specific transcripts was ca. 1.5 kilobases in size, as expected for a tk-specific mRNA containing the entire coding region of the gene. Thus, disproportionate DNA replication appeared not to be essential for an active tk gene expression in these cells. We discuss possible pathways leading to the formation of tandem arrays of integrated truncated tk genes and the conditions required for disproportionate DNA replication in the unique case in which we found a retraction and expansion of tk gene copy numbers as a response to selective growth conditions.

scholarly journals Persistence of Tandem Arrays: Implications for Satellite and Simple-Sequence DNAs

Genetics ◽  
1987 ◽  
Vol 115 (3) ◽  
pp. 553-567 ◽  
Author(s):  
James Bruce Walsh
Keyword(s):  
Gene Amplification ◽  
Array Size ◽  
Crossing Over ◽  
Unequal Crossing Over ◽  
Deletion Rate ◽  
Recombination Processes ◽  
Number Dynamics ◽  
Equilibrium Distributions ◽  
Simple Sequence ◽  
Tandem Arrays

ABSTRACT Recombination processes acting on tandem arrays are suggested here to have probable intrinsic biases, producing an expected net decrease in array size following each event, in contrast to previous models which assume no net change in array size. We examine the implications of this by modeling copy number dynamics in a tandem array under the joint interactions of sister-strand unequal crossing over (rate γ per generation per copy) and intrastrand recombination resulting in deletion (rate ∊ per generation per copy). Assuming no gene amplification or selection, the expected mean persistence time of an array starting with z excess copies (i.e., array size z + 1) is z(1 + γ/∊) recombinational events. Nontrivial equilibrium distributions of array sizes exist when gene amplification or certain forms of selection are considered. We characterize the equilibrium distribution for both a simple model of gene amplification and under the assumption that selection imposes a minimal array size, n. For the latter case, n + 1/03B1 is an upper bound for mean array size under fairly general conditions, where α(=2∊/γ) is the scaled deletion rate. Further, the distribution of excess copies over n is bounded above by a geometric distribution with parameter α/(1 + α). Tandem arrays are unlikely to be greatly expanded by unequal crossing over unless α << 1, implying that other mechanisms, such as gene amplification, are likely important in the evolution of large arrays. Thus unequal crossing over, by itself, is likely insufficient to account for satellite DNA.

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