DNA replication: the recombination connection. Indeed, POT1a genes are under positive selection and these changes enhance POT1 binding with CST, presumably to promote telomerase engagement with the telomere (Beilstein et al., 2015). B each type of tissue performs specific, Following are the main parts of gut where digestion occurs except A) oral cavity B) stomach C) small intestine C) large intestine, Do prokaryotic cells have membrane enclosed cell structures. alternative lengthening of telomeres; break-induced replication; mitotic DNA synthesis; replication stress; telomeres. Why are telomeres important? For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. This is called the end replication problem . However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. Although t-loops are highly conserved, their actual structure varies between species. National Library of Medicine This content is currently under construction. Tetrahymena is a large unicellular protozoan with two nuclei, the macronucleus and the micronucleus (Figure 1). 2022 Jan;32(1):45-57. doi: 10.1016/j.tcb.2021.07.005. A., & Reddel, R. R. Telomere maintenance and cancerLook, no telomerase. TRs from these three plant lineages were shown to share a conserved core structure consisting of a template-adjacent PK core domain similar to ciliate and animal TRs, and a template-distal helical domain P4/5/6 crucial for telomerase activity, similar to the helix IV and CR4/5 of ciliate and animal TRs, respectively (Figure1). Declaration of interests No interests are declared. Telomere shortening and tumor formation by mouse cells lacking telomerase RNA. The phylogenetic approach allowed inference of a conserved secondary structure model from the alignment of plant TR sequences identified from major clades of land plant species including angiosperms, gymnosperms, and lycophytes (Song et al., 2019). This is consistent with the Pol II first hypothesis of TR transcription evolution and that an early Pol II-to-Pol III switch occurred in the common ancestor of ciliates and plants (Figure1). In the absence of telomerase, 4-11% of tumors rely on ALT to maintain telomeres for extended proliferation [25]. Since a free 3 OH group is needed for DNA replication and a new strand of DNA to be synthesized, this creates a problem for the ends of linear DNA molecules, such as those we see in eukaryotic cells. (, Logeswaran D, Li Y, Podlevsky JD, Chen JJL (, Marian CO, Bordoli SJ, Goltz M, Santarella RA, Jackson LP, Danilevskaya O, Beckstette M, Meeley R, Bass HW (, Miller AS, Balakrishnan L, Buncher NA, Opresko PL, Bambara RA (, Mozgova I, Schrumpfova PP, Hofr C, Fajkus J (, Nugent CI, Hughes TR, Lue NF, Lundblad V (, Opresko PL, Fan J, Danzy S, Wilson DM, Bohr VA (, Orsolic I, Jurada D, Pullen N, Oren M, Eliopoulos AG, Volarevic S (, Qian W, Kumar N, Roginskaya V, Fouquerel E, Opresko PL, Shiva S, Watkins SC, Kolodieznyi D, Bruchez MP, Van Houten B (, Raices M, Verdun RE, Compton SA, Haggblom CI, Griffith JD, Dillin A, Karlseder J (, Renfrew KB, Song X, Lee JR, Arora A, Shippen DE (, Riha K, McKnight TD, Fajkus J, Vyskot B, Shippen DE (, Riha K, McKnight TD, Griffing LR, Shippen DE (, Riha K, Watson JM, Parkey J, Shippen DE (, Rossignol P, Collier S, Bush M, Shaw P, Doonan JH (, Sandhu R, Sanford S, Basu S, Park M, Pandya UM, Li B, Chakrabarti K (, Schuermann D, Molinier J, Fritsch O, Hohn B (, Sewelam N, Brilhaus D, Brautigam A, Alseekh S, Fernie AR, Maurino VG (, Shakirov EV, Perroud PF, Nelson AD, Cannell ME, Quatrano RS, Shippen DE (, Shakirov EV, Song X, Joseph JA, Shippen DE (, Shakirov EV, Surovtseva YV, Osbun N, Shippen DE (, Song J, Castillo-Gonzalez C, Ma Z, Shippen DE (, Song J, Logeswaran D, Castillo-Gonzalez C, Li Y, Bose S, Aklilu BB, Ma Z, Polkhovskiy A, Chen JJL, Shippen DE (, Surovtseva YV, Churikov D, Boltz KA, Song X, Lamb JC, Warrington R, Leehy K, Heacock M, Price CM, Shippen DE (, Surovtseva YV, Shakirov EV, Vespa L, Osbun N, Song X, Shippen DE (, Tseng CK, Wang HF, Burns AM, Schroeder MR, Gaspari M, Baumann P (, Ungar L, Yosef N, Sela Y, Sharan R, Ruppin E, Kupiec M (, Valuchova S, Fulnecek J, Prokop Z, Stolt-Bergner P, Janouskova E, Hofr C, Riha K (, Walne AJ, Vulliamy T, Marrone A, Beswick R, Kirwan M, Masunari Y, Al-Qurashi FH, Aljurf M, Dokal I (, Wang H, Ni J, Guo X, Zhou T, Ma X, Xue J, Wang X (, Watson JM, Trieb J, Troestl M, Renfrew K, Mandakova T, Fulnecek J, Shippen DE, Riha K (, Zandalinas SI, Sengupta S, Fritschi FB, Azad RK, Nechushtai R, Mittler R (, Oxford University Press is a department of the University of Oxford. 8600 Rockville Pike Therefore, continued proliferation under conditions of replication stress requires a means of telomere repair, particularly . Nature Reviews Molecular Cell Biology 4, 948959 (2003) doi:10.1038/nrm1256 (link to article). FOIA 'Starts Today' : 'remaining' }} When taken in isolation, allelic differences at this QTL explain 42.2% of the total mean telomere length variation present in the MAGIC population (Abdulkina et al., 2019). Do telomeres influence pace-of-life-strategies in response to environmental conditions over a lifetime and between generations? Researchers now know that tandem repeats of short GT-rich sequences are characteristic of almost all eukaryotic telomeres (Vega et al., 2003; de Lange, 2004; McKnight & Shippen, 2004). However, these structures present obstacles during DNA replication. Telomerase continually replenishes DNA termini by reiteratively copying a templating domain within its integral TR subunit to synthesize telomeric repeats de novo. By maintaining a sufficient length of telomeric DNA on chromosome ends, telomerase ensures that the terminus will be properly sequestered. In the mid-1970s, Elizabeth Blackburn, who was working as a postdoctoral associate in Joseph Gall's laboratory, set out to determine the telomere sequences of a minichromosome that contained the Tetrahymena ribosomal DNA sequence. official website and that any information you provide is encrypted One thing is One could argue that the minichromosomes are not true chromosomes, because they lack centromeres and are not passed down to progeny. Unauthorized use of these marks is strictly prohibited. Telomere research in our labs is supported by grants from the National Institutes of Health (R01-GM065383 to D.E.S. Careers. Reprod Fertil Dev. Please enable it to take advantage of the complete set of features! To ensure that the chromosome terminus is fully protected, any alteration in the telomere DNA repeats requires corresponding mutations in the RNA component of telomerase as well as co-evolution of the telomere-binding proteins (Shakirov et al., 2009). Because of their advanced genomic and mapping resources and the capacity to test the functions and interactions of identified genes, plants present an unparalleled opportunity to analyze natural telomere length variation and to discover causal genes establishing genotype-specific telomere length polymorphism (Koornneef et al., 2004; Shakirov and Shippen, 2004; Maillet et al., 2006). solve the end replication problem)? Consequently, each macronucleus is estimated to contain about 10,000 minichromosomes. For example, a group of Asparagales switched to the vertebrate-type TTAGGG repeat (Adams et al., 2001), while Allium evolved with a long telomere repeat CTCGGTTATGGG synthesized by telomerase with a long RNA template (Fajkus et al., 2016). Discovery of Telomeres and Telomerase. The actual length of the G-tail is somewhat variable, averaging between 75-300 nucleotides in humans and 50-100 nucleotides in yeast. Although systematic deletion screens implicate many genes in telomere length maintenance (Askree et al., 2004; Gatbonton et al., 2006; Liu et al., 2010), the relative contribution of each gene is unclear. The study of telomeres in the context of ecology and evolution represents a new frontier with exciting opportunities for identification of factors affecting both telomere length and adaptation to the environmental conditions or stress (Monaghan and Haussmann, 2006; Bize et al., 2009). Fingering the ends: how to make new telomeres. As you find each piece of equipment, record its name on the list. Front Immunol. Before AtPOT1c is a nonfunctional gene that was silenced soon after it emerged (Kobayashi et al., 2019). In addition, resources cataloging the abundant natural variation in Arabidopsis thaliana, maize (Zea mays), and other plants are providing unparalleled opportunities to understand the genetic networks that govern telomere length polymorphism and, as a result, are uncovering unanticipated crosstalk between telomeres, environmental factors, organismal fitness, and plant physiology. Altogether, the discussed results argue for an expanded definition of the end-replication problem that includes replication stress as a significant source of telomere attrition and limited cell proliferation. The remarkable stability of plant telomeres may reflect the multiple modes of telomere length regulation and thus highlight their novel adaptations to a life rooted in the ground. Despite the magnitude of these discoveries, 40 years would elapse between McClintock's original observations and the experiments that revealed the actual structure of telomeres. Several of these not only bear a single Myb domain with a telobox motif structurally similar to the vertebrate shelterin components TRF1 and TRF2 proteins (Zellinger and Riha, 2007), but also bind telomeric DNA in vitro (Marian et al., 2003; Karamysheva et al., 2004; Kuchar and Fajkus, 2004; Mozgova et al., 2008). 2021;16(7):809-823. doi: 10.2174/1574888X15666200422104423. Disclaimer. report that a large number of proteins engage Arabidopsis telomerase (Fulneckova et al., 2021). Continued shortening occurs until they reach a minimum functional length threshold of 400bp, below which all telomeres become fused triggering massive genome instability. 2022 Dec 12;5(4):281-286. doi: 10.1002/agm2.12231. Quite unexpectedly, the elongated telomeres had repeated copies of the yeast TG1-3 repeat, rather than the Tetrahymena TTGGGG repeat. The site is secure. what statement is true regarding the tissue in animal organs A QTL analysis in a maize mapping population uncovered nine QTL for mean telomere length that collectively explained over 30% of the phenotypic variation for telomere length (Brown et al., 2011). A new quantitative assay to measure telomeric 8-oxoG in Arabidopsis provides strong support for this hypothesis, showing telomeres accumulate 8-oxoG at levels 100 times greater than the rest of the genome, and are the primary target upon oxidative stress (Castillo-Gonzlez et al., 2022). See this image and copyright information in PMC. Top, telomere replication primarily initiates from origins within, Figure 2.. Carol Greider, then a graduate student in Blackburn's lab, decided to look for an activity in Tetrahymena extracts that could add nucleotides to a synthetic oligonucleotide that contained four copies of the Tetrahymena telomere repeat. Telomere function relies on both the proper length of the telomeric DNA tract and the integrity of the telomere-binding protein complexes that recognize and bind telomeric DNA, either double- or single stranded. 2020 May 1;11(3):576-601. doi: 10.1093/advances/nmz107. The incomplete copying of template margin in enzymic synthesis of polynucleotides and biological significance of the phenomenon, Oxidative damage in telomeric DNA disrupts recognition by TRF1 and TRF2, The relationship between the nucleolus and cancer: current evidence and emerging paradigms, Origin, diversity, and evolution of telomere sequences in plants, Evolutionary perspectives of telomerase RNA structure and function, The functional requirement of two structural domains within telomerase RNA emerged early in eukaryotes, Chemoptogenetic damage to mitochondria causes rapid telomere dysfunction, POT1a and components of CST engage telomerase and regulate its activity in Arabidopsis, Analysis of the G-overhang structures on plant telomeres: evidence for two distinct telomere architectures, Living with genome instability: plant responses to telomere dysfunction, Telomere length deregulation and enhanced sensitivity to genotoxic stress in Arabidopsis mutants deficient in Ku70, Arabidopsis POT1A interacts with TERT-V(I8), an N-terminal splicing variant of telomerase, The telomere paradox: stable genome preservation with rapidly evolving proteins, A trans-spliced telomerase RNA dictates telomere synthesis in, Mitochondrial localization of telomerase as a determinant for hydrogen peroxide-induced mitochondrial DNA damage and apoptosis, Telomere- and telomerase-associated proteins and their functions in the plant cell, The dual nature of homologous recombination in plants, Molecular plant responses to combined abiotic stresses put a spotlight on unknown and abundant genes, Protection of Telomeres 1 is required for telomere integrity in the moss Physcomitrella patens, Length regulation and dynamics of individual telomere tracts in wild-type Arabidopsis, POT1 proteins in green algae and land plants: DNA-binding properties and evidence of co-evolution with telomeric DNA, The Arabidopsis Pot1 and Pot2 proteins function in telomere length homeostasis and chromosome end protection, Arabidopsis retains vertebrate-type telomerase accessory proteins via a plant-specific assembly, The conserved structure of plant telomerase RNA provides the missing link for an evolutionary pathway from ciliates to humans, Conserved telomere maintenance component 1 interacts with STN1 and maintains chromosome ends in higher eukaryotes, Arabidopsis POT1 associates with the telomerase RNP and is required for telomere maintenance, Human telomerase RNA processing and quality control, A genome-wide screen for essential yeast genes that affect telomere length maintenance, Protection of Arabidopsis blunt-ended telomeres is mediated by a physical association with the Ku heterodimer, Genetic heterogeneity in autosomal recessive dyskeratosis congenita with one subtype due to mutations in the telomerase-associated protein NOP10, Shelterin differentially respond to oxidative stress induced by TiO2-NPs and regulate telomere length in human hepatocytes and hepatocarcinoma cells in vitro, Telomeres, aging, and plants: from weeds to Methuselah - a mini-review, Telomere rapid deletion regulates telomere length in, A hypomorphic allele of telomerase uncovers the minimal functional length of telomeres in Arabidopsis, Telomeric 3' overhangs derive from resection by Exo1 and Apollo and fill-in by POT1b-associated CST, DDM1 guards against telomere truncation in Arabidopsis, The impact of multifactorial stress combination on plant growth and survival, American Society of Plant Biologists 2022. Figure 3.. Cellular Response to Replication Stress at Telomeres. The incomplete synthesis takes place at the lagging strand during eukaryotic replication, where a RNA primer is needed for the synthesis of the Okazaki fragments and DNA polymerase leaves a 3' hydroxyl group at the end of the sequence. Notably, worms (Caenorhabditis elegans) are predicted to harbor four putative POT1 paralogs; one of these binds the G-rich telomeric DNA strand and another the complementary C-rich strand (Raices et al., 2008). Disclaimer. Telomere maintenance is a fundamental cellular process conserved across all eukaryotic lineages. Bottom, single-ended DSBs can complete replication through break-induced replication (BIR). Plant Cell 16, 794803 (2004), Neumann, A. Telomere-related mutations that are lethal in mammalian cells and even yeast can be viable in Arabidopsis (Surovtseva et al., 2007, 2009; Leehy et al., 2013). Focus on plant genetics: Celebrating Gregor Mendel's 200th birth anniversary. Figure 1.. Replication Fork Obstacles within Telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. The chromosomes in the Tetrahymena micronucleus terminate in t-loops, but the minichromosomes in its macronucleus lack t-loops and are simply capped by a tenacious binding protein. This resilience is on full display in Arabidopsis mutants devoid of telomerase or proteins implicated in chromosome end protection. Consequently, the gene NOP2A/OLI2 was identified as the main candidate behind this QTL. Telomeres protect chromosome ends from fusion and from being recognized as sites of DNA damage (Box 1). Here is a picture of using telomerase in solving end replication problem (Courtesy: Molecular Biology of the Cell, Alberts, Garland Science Pub.) 2022 Dec 2;10(2):uhac264. What value would be returned based on the formula in cell a49. S. cerevisiae telomeres typically contain about 60-100 copies of the sequence C1-3A/TG1-3. Nature Reviews Cancer 2, 879884 (2002) doi:10.1038/nrc929 (link to article), Selker, E. U. Together, the t-loop and telomere-associated proteins ensure that chromosome termini do not solicit the DNA damage checkpoint machinery, leading to extensive DNA degradation or end-to-end chromosome fusion. A self-help guide for a trim genome. Complimentary 1-hour tutoring consultation Such adaptations include pleiotropy of important genes that connect telomeres to plant physiology and stress response in unanticipated ways. Notably, human NOP2 associates with telomerase and through direct contacts with TERT stimulates transcription of cyclin D1 (Hong et al., 2016). {{ nextFTS.remaining.days === 0 ? hPOT1 is among several shelterin components that can stimulate base excision repair (BER) (Miller et al., 2012), the primary pathway for removing 8-oxoG from DNA. Telomerase is active in germ cells, embryonic cells, and some somatic cells, but not in the endosperm cells that McClintock examined (McKnight & Shippen, 2004). Telomerase RNA in Hymenoptera (Insecta) switched to plant/ciliate-like biogenesis. Telomeres in Plants and Humans: Not So Different, Not So Similar. ribosome biology and rRNA maturation). Resolving Roadblocks to Telomere Replication. Disclaimer. 3. sharing sensitive information, make sure youre on a federal The .gov means its official. Investigation into this mystery began when Blackburn and Szostak sequenced the ends of linear DNA molecules from Tetrahymena and were able to ligate to the ends of yeast cells DNA. Since the discovery of telomerase, it has become clear that this substance plays a key role in the regulation of telomere length. Other variant repeat sequences have also been described in select groups of plant species (Peska and Garcia, 2020). Epub 2013 Dec 10. We have been studying telomere replication in hypotrichous ciliates such as Euplotes aediculatus, which have numerous short macronuclear DNA molecules and therefore are highly enriched in telomeres and in telomerase.Cloning and sequencing genes for the RNA subunits from . Vega, L. R., et al. Right, precancerous or cancerous cells with compromised cell cycle checkpoints restart telomere replication through break-induced replication (BIR) and mitotic DNA synthesis (MiDAS). area of current research, and new insights into telomeres and their role in The conserved TR secondary structure model was further validated by in vivo chemical probing and functional analysis of individual base-paired regions (Song et al., 2019). R01 GM065383/GM/NIGMS NIH HHS/United States, R01 GM127402/GM/NIGMS NIH HHS/United States. An official website of the United States government. FOIA Arabidopsis thaliana mutations in telomerase constituents trigger an inexorable depletion of telomeric DNA through successive generations (Riha et al., 2000), while disruption of CST causes a rapid and catastrophic loss of telomeric DNA (Surovtseva et al., 2009). 2003 May 30;113(5):552-4. doi: 10.1016/s0092-8674(03)00397-0. As shown in the figure below, it binds to a special RNA molecule that is complementary to the telomere at the chromosome end. It was foreseen in the 1970s that conventional DNA polymerases are incapable of fully replicating the very termini of linear chromosomes (Watson, 1972; Olovnikov, 1973), causing a gradual attrition of telomere DNA over cell divisions that would ultimately result in chromosome end-deprotection. As a graduate student in Blackburns laboratory, Greider was able to identify G-rich rDNA molecules in Tetrahymena that contained the necessary 3-OH group for DNA replication that was complementary to the repeats seen in the telomere sequences. Int J Mol Sci. A problem arises at the end of the chromosome, however, because the DNA repair machinery is unable to repair the gap left by the terminal RNA primer. Two protein subunits, 123 kDa and 43 kDa, were identified. We have been studying telomere replication in hypotrichous ciliates such as Euplotes aediculatus, which have numerous short macronuclear DNA molecules and therefore are highly enriched in telomeres and in telomerase. HHS Vulnerability Disclosure, Help If the original chromosome reformed when such contact occurred, then the cycle of breakage and fusion could be repeated. However, these structures present obstacles during DNA replication. Cloning and sequencing genes for the RNA subunits from several ciliates revealed that telomerase RNAs with insignificant nucleotide sequence homology nevertheless form a common secondary structure. HHS Vulnerability Disclosure, Help The MAC contains about 50 copies each of countless minichromosomes derived during sexual conjugation by rearrangement and amplification of sequences originating from the silent micronucleus (MIC). For example, in Tetrahymena thermophila, one POT1 paralog is needed for telomere length maintenance and checkpoint repression, while the other functions in developmentally programmed genome reorganization (Jacob et al., 2007; Cranert et al., 2014). As a result, chromosome ends have long stretches of repetitive DNA called telomeres that protect genes from being lost. They were also able to identify repeated C1-3A sequences in telomeres of both organisms. These new findings provide unanticipated insight into telomere maintenance and regulation as well as evolutionary surprises to unite telomere research across the Eukarya domain. Various proteins that transiently interact with shelterin as well as DNA and RNA maintenance pathways remove these obstacles to prevent replication fork stalling and collapse [94]. In the wild-type Col-0 accession, telomeres are typically maintained in the 2.53kb range (Shakirov and Shippen, 2004). When the overhang is long enough, a matching DNA strand can be made by the normal DNA replication machinery (that is, using an RNA primer and DNA polymerase), producing double-stranded DNA at the chromosome end. As with very short telomeres, ultra-long telomeres are unstable and undergo stochastic telomere trimming (TRD) and the formation of extra chromosomal telomeric circles (Watson and Shippen, 2007). In this long tradition, Barbara McClintocks studies in maize (Zea mays) some 80years ago revealed the critical function of telomeres (McClintock, 1939, 1941). G quadruplexes are unwound by BLM and RTEL1 helicases [11, 44, 95]. Science 300, 15171518 (2003) doi:10.1126/science.1086053. 2) DNA ligase links the 5 OH group of one fragment to the 3 phosphate group of an adjacent fragment. In this article, we highlight recent discoveries in plant telomere research facilitated by technological advances in nucleic acid biochemistry, the advent of abundant genomic resources, and the ability to harness natural variation across different species. ; R01-GM127402 to E.V.S. government site. An official website of the United States government. {{ nextFTS.remaining.months > 1 ? View the full answer. Yet, nearly 10years later, a re-examination of this locus using a clustered regularly interspaced short palindromic repeats (CRISPR)-edited mutant that disrupted the putative TR template did not result in telomere shortening, casting doubt on this RNA as a bona fide plant TR (Dew-Budd et al., 2020). AtPOT1a binds telomeric DNA in vitro, but unlike PpPOT1 it is not essential for chromosome end protection. eCollection 2023 Jan. Fajkus P, Admik M, Nelson ADL, Kilar AM, Franek M, Bubenk M, Frydrychov R, Votavov A, Skorov E, Fajkus J, Peka V. Nucleic Acids Res. Mechanisms that establish telomere length set point are under intense investigation. Mutations that result in mild telomere shortening or reestablish a new shorter telomere length equilibrium of ~1.5kb (NUCLEOLAR PROTEIN 2 (NOP2A)/OLIGOCELLULA 2 (OLI2), DNA replication and repair mutants, transposon control mutants) do not impact chromosome stability (Xie and Shippen, 2018; Abdulkina et al., 2019; Bose et al., 2020). 2022 Jan 11;20:675-684. doi: 10.1016/j.csbj.2022.01.005. A wide range of genotype-specific telomere lengths has also been uncovered in Arabidopsis accessions (Shakirov and Shippen, 2004; Fulcher and Riha, 2015), confirming that QTL and GWAS mapping represent a promising route to identify causal loci responsible for the standing genetic diversity in telomere length. Due to its remarkable sequence diversity, identification of TR from a new kingdom or new group of eukaryotic species is challenging and often unsuccessful. Telomere proteins evolve rapidly (Linger and Price, 2009; Lue, 2010; Saint-Leandre and Levine, 2020). This so-called "end-replication" problem, which is graphically depicted in Figure 4a, is a direct consequence of DNA polymerase's biochemical properties. Telomeric MiDAS is almost exclusively replicated conservatively, while CFSs appear to partially rely on a semi-conservative replication mechanism. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. 2023 May;18(5):959-968. doi: 10.4103/1673-5374.355751. Deletion of this RNA in vivo led to telomere shortening and the lack of detectable telomerase activity, which indicate an essential role of this RNA in telomerase function. Bottom, the guanine-rich repetitive sequences and secondary structures within telomeres present obstacles to replisome progression during semi-conservative DNA replication, indicated by stars. This site needs JavaScript to work properly. The effects of telomere failure are similarly manifested in plants. MiDAS at CFSs and telomeres share common BIR-associated factors and are both dependent on the SLX4 nuclease scaffold protein, although CFS MiDAS requires the Mus81-EME1 nuclease while telomeric MiDAS does not. Ageing; DNA damage; Senescence; Telomerase; Telomere. The addition of the G-rich oligonucleotide were also shown in vitro to enzymatically be added to yeast telomeric DNA. Accessibility The telomere terminal transferase of Tetrahymena is a ribonucleoprotein enzyme with two kinds of primer specificity, Mammalian telomeres end in a large duplex loop, Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells: a prospective trial, Longer telomeres associated with higher survival in birds, Molecular analysis of telomere fusions in Arabidopsis: multiple pathways for chromosome end-joining, Telomerase activates transcription of cyclin D1 gene through an interaction with NOL1, The Arabidopsis transcriptome responds specifically and dynamically to high light stress, Tetrahymena POT1a regulates telomere length and prevents activation of a cell cycle checkpoint, The power of stress: the telo-hormesis hypothesis, Dyskerin is a component of the Arabidopsis telomerase RNP required for telomere maintenance, A C-terminal Myb extension domain defines a novel family of double-strand telomeric DNA-binding proteins in Arabidopsis, Chromosome end protection by blunt-ended telomeres, Recent emergence and extinction of the protection of telomeres 1c gene in, Naturally occurring genetic variation in A, Pathogen-induced systemic plant signal triggers DNA rearrangements, Interactions of putative telomere-binding proteins in, Stress-induced intrachromosomal recombination in plant somatic cells, Dynamic interactions of Arabidopsis TEN1: stabilizing telomeres in response to heat stress, MERISTEM DISORGANIZATION1 encodes TEN1, an essential telomere protein that modulates telomerase processivity in Arabidopsis, Genome-wide association identifies OBFC1 as a locus involved in human leukocyte telomere biology, A novel mechanism for telomere size control in, Stress and telomere shortening: insights from cellular mechanisms, Conservation of telomere protein complexes: shuffling through evolution, Monophyletic origin and divergent evolution of animal telomerase RNA, Plasticity of telomere maintenance mechanisms in yeast, Duplication and functional specialization of the telomere-capping protein Cdc13 in Candida species, Telomere-length regulation in inter-ecotype crosses of Arabidopsis, DNA damage and repair in plants - from models to crops, The maize Single myb histone 1 gene, Smh1, belongs to a novel gene family and encodes a protein that binds telomere DNA repeats in vitro, The Behavior in successive nuclear divisions of a chromosome broken at meiosis, The stability of broken ends of chromosomes in, Telomere proteins POT1, TRF1 and TRF2 augment long-patch base excision repair in vitro.

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