A family of complex tandem DNA repeats in the telomeres of Chironomus pallidivittatus.

Yj, Zhang; Kamnert, Iréne; López, Casimiro C.; Cohn, Marita; Edström, Jan‐Erik

doi:10.1128/mcb.14.12.8028

Cited by 35 publications

(44 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Species that had no cross-hybridization included the five Diptera and three of the eight Coleoptera studied. Lack of cross-hybridization does not prove that a species lacks telomerase; however, at least two Diptera, D. melanogaster and Chironomous pallidivittatus, are known to have chromosome end sequences that differ significantly from the simple repeats generated by telomerase (2,23,24). Thus these species have either lost telomerase or, as we have argued (3,25), their telomerase has undergone significant evolution.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Unusual features of theDrosophila melanogastertelomere transposable elementHeT-Aare conserved inDrosophila yakubatelomere elements

Danilevskaya

Tan

Wong

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

HeT-A was the first transposable element shown to have a bona fide role in chromosome structure, maintenance of telomeres in Drosophila melanogaster. HeT-A has hallmarks of non-long-terminal-repeat (non-LTR) retrotransposable elements but also has several unique features. Drosophila telomeres appear to be very different from those of other organisms. (Telomeres are ends of chromosomes and have important roles in chromosome organization.) In Drosophila melanogaster the telomeres are not maintained by telomerase, which maintains telomeres in most animals, plants, and single-celled eukaryotes (1). Instead, Drosophila telomeres are elongated by transposition of two unusual retrotransposons, HeT-A and TART, onto chromosome ends (2). This unusual telomere mechanism offers insights into the requirements for telomere function. It also raises the possibility that transposable elements evolved from normal cellular elements, such as telomeres (3). We have now isolatedRetrotransposon-type telomeres have been reported only for D. melanogaster and the closely related Drosophila simulans. It is of interest to know how many other species share this mechanism of telomere maintenance. This information will be helpful in estimating the antiquity of the mechanism and understanding how it has evolved. Furthermore, comparison of telomere transposon sequences from different species can give insight into the characteristics of these elements that are crucial for their role in telomeres.Analyses of several HeT-A sequences isolated from D. melanogaster have shown that intact and potentially functional elements can differ markedly in both coding and noncoding regions (4-7). Because HeT-A variation increases rapidly with evolutionary distance, it is difficult to use sequence homology . The conservation of these features argues that they are important for the role of HeT-A elements in telomeres (see Fig. 1 for diagrams of HeT-A elements).

show abstract

Section: Discussionmentioning

confidence: 99%

“…Telomeres in D. melanogaster are composed of the retrotranposons, HeT-A and TART, whereas telomeres in C. pallidivittatus and Chironomous thummi are composed of large complex repeats (23,24). The mechanism by which the Chironomous repeats are generated is not known.…”

Section: Discussionmentioning

confidence: 99%

Unusual features of theDrosophila melanogastertelomere transposable elementHeT-Aare conserved inDrosophila yakubatelomere elements

Danilevskaya

Tan

Wong

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…D. melanogaster actually lacks telomeric repeats, as shown by the failure to cross-hybridize with various oligonucleotides whose design is based on several telomeric sequences [28±30]. In addition, two other Diptera, Chironomus [31,32] and Anopheles [7], also seem to have no (TTAGG) n repeats. That we could not detect telomerase activity in two Drosophila and one Sarcofaga cell lines in this study, is consistent with the observed telomeric repeat missing in Diptera.…”

Section: Discussionmentioning

confidence: 99%

Detection and distribution patterns of telomerase activity in insects

Sasaki¹,

Fujiwara²

2000

Eur J Biochem

View full text Add to dashboard Cite

Telomeres of most insects consist of pentanucleotide (TTAGG) n repeats, although the repeats are absent in Diptera and some other insect species, where the telomere regions are perhaps maintained without telomerase. To understand various and unusual telomere formation in insects, we have studied the characteristic features of a putative insect telomerase that has not been previously described. Using a modified telomeric repeat amplification protocol (TRAP), we first detected the telomerase activity in crickets, cockroaches and two Lepidopteran insects. The telomerase from crickets and cockroaches required dATP, dGTP and dTTP but not dCTP as a substrate and sequence analyses of the products of TRAP revealed that the (TTAGG) n repeats are synthesized by telomerase. The cockroach telomerase was detected both in somatic (fat body, muscle and neural tissues) and germ line (testis) cells, suggesting that expression of this enzyme is not regulated in a tissue-specific manner at an adult stage. While we detected high levels of telomerase activity in crickets and cockroaches, we could not detect activity in all tissues and cell cultures of the silkworm, Bombyx mori and in two Drosophila and one Sarcophaga cell lines. This supports the theory that Dipteran insects maintain their telomeres without telomerase.

show abstract

“…We first converted the blocks of repeats in the extracted DNA to monomers with HaeIII, which restricts the majority of repeats in all subfamilies (7,27). The initial part of L4, containing subfamily-specific restriction sites (7,34), lies in the middle of the released monomers. We used primers on both sides of this region for amplification.…”

Section: Figmentioning

confidence: 99%

“…In the case of D3 there is a second difference, i.e., one large region has become substituted for another one. Telomeres differ in subfamily composition (8,34). When D3 is present together with other kinds of repeats, it is always the most peripheral unit (34).…”

mentioning

confidence: 99%

Terminal Long Tandem Repeats in Chromosomes from Chironomus pallidivittatus

López

Nielsen

Edström

1996

Molecular and Cellular Biology

Self Cite

View full text Add to dashboard Cite

We provide evidence that a chromosome end in the dipteran Chironomus pallidivittatus contains 340-bp tandem repeats reaching the extreme terminus of the chromosome. After adding synthetic oligonucleotide tails to DNA extracted from the microdissected right end of the fourth chromosome, we could demonstrate that the blocks of repeats were tailed at only one end, the chromosome terminus, the interior of the arrays being unavailable for tailing. Using PCR, we furthermore showed that the added tails were connected to 340-bp repeat DNA directly, i.e., without intervening DNA of any other kind. The tailed repeats belong to a subfamily previously known to be the most peripheral one of the different types of 340-bp units. Using plasmid controls, we could also make certain that we did not amplify rare or nonrepresentative DNA termini.Telomeres of most investigated eukaryotic species terminate with short repeats, usually with guanine excess in the 3Ј-terminating strand (4). Such repeats, whether regular, as in most cases (5,17,21,25), or irregular, as in Saccharomyces cerevisiae (29) among others, are likely to result from telomerase activities (6,11,16,31).Short repeats are also found in several insect orders (23), but for the dipteran Drosophila melanogaster a different mode of chromosome termination has been established. Here terminally deleted chromosomes can be capped by non-long-terminal-repeat retrotransposons (2,3,30,33), which can also be recovered at the ends of normal chromosomes (15).No other type of ending is known for nuclear chromosomes, but the linear mitochondrial DNA from Tetrahymena thermophila ends with Ͼ50-bp-long repeat units (19,20). We present evidence that this alternative, here in the form of 340-bp tandem repeats (27), is used by nuclear chromosomes in the dipteran Chironomus pallidivittatus.The 340-bp tandem repeat family is localized at seven of the eight (pairs of) chromosome ends in Ͻ200-kb blocks. Although the blocks are close to the chromosome ends as revealed by Bal 31 digestions (34), it has not been known whether they reach the extreme termini. The repeat family contains four different subfamilies, three of which, D1, D2, and D3, are derived from the fourth one, M1, each by a cluster of mutations in short regions designated ds1, ds2, and ds3, respectively (7). In the case of D3 there is a second difference, i.e., one large region has become substituted for another one. Telomeres differ in subfamily composition (8,34). When D3 is present together with other kinds of repeats, it is always the most peripheral unit (34).Briefly, our strategy was to gently release DNA from single microdissected right ends of the fourth chromosome and provide it with tails. Anchors added to the tails and primers for the 340-bp repeat were used for PCR amplifications. We could demonstrate that no internal breaks were tailed within the repeat blocks and that the tails were added directly to the 340-bp repeat DNA. We also showed that only DNA from a specific subfamily, previously shown to be distal (34), was amp...

show abstract

A family of complex tandem DNA repeats in the telomeres of Chironomus pallidivittatus.

Cited by 35 publications

References 58 publications

Unusual features of theDrosophila melanogastertelomere transposable elementHeT-Aare conserved inDrosophila yakubatelomere elements

Unusual features of theDrosophila melanogastertelomere transposable elementHeT-Aare conserved inDrosophila yakubatelomere elements

Detection and distribution patterns of telomerase activity in insects

Terminal Long Tandem Repeats in Chromosomes from Chironomus pallidivittatus

Contact Info

Product

Resources

About