scholarly journals The genetic basis of natural variation in C. elegans telomere length

2016 ◽  
Author(s):  
D.C. Cook ◽  
S. Zdraljevic ◽  
R.E. Tanny ◽  
B. Seo ◽  
D.D. Riccardi ◽  
...  
Keyword(s):  
Telomere Length ◽  
Natural Variation ◽  
Genome Instability ◽  
Length Variation ◽  
Genetic Determinants ◽  
Telomeric Dna ◽  
C Elegans ◽  
Offspring Production ◽  
Telomere Capping ◽  
Organismal Fitness

AbstractTelomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligosaccharide/oligonucleotide-binding fold of POT-2, a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans.

scholarly journals Genetic Dissection of the Kluyveromyces lactis Telomere and Evidence for Telomere Capping Defects in TER1 Mutants with Long Telomeres

2004 ◽  
Vol 3 (2) ◽  
pp. 369-384 ◽  
Author(s):  
Dana H. Underwood ◽  
Coleen Carroll ◽  
Michael J. McEachern
Keyword(s):  
Binding Site ◽  
Telomere Length ◽  
Kluyveromyces Lactis ◽  
Genetic Dissection ◽  
Wild Type ◽  
Telomeric Dna ◽  
Telomeric Repeats ◽  
Functional Regions ◽  
Telomere Capping ◽  
Terminal Repeats

ABSTRACT In the yeast Kluyveromyces lactis, the telomeres are composed of perfect 25-bp repeats copied from a 30-nucleotide RNA template defined by 5-nucleotide terminal repeats. A genetic dissection of the K. lactis telomere was performed by using mutant telomerase RNA (TER1) alleles to incorporate mutated telomeric repeats. This analysis has shown that each telomeric repeat contains several functional regions, some of which may physically overlap. Mutations in the terminal repeats of the template RNA typically lead to telomere shortening, as do mutations in the right side of the Rap1p binding site. Mutations in the left half of the Rap1p binding site, however, lead to the immediate formation of long telomeres. When mutated, the region immediately 3′ of the Rap1p binding site on the TG-rich strand of the telomere leads to telomeres that are initially short but eventually undergo extreme telomere elongation. Mutations between this region and the 3′ terminal repeat cause elevated recombination despite the presence of telomeres of nearly wild-type length. Mutants with highly elongated telomeres were further characterized and exhibit signs of telomere capping defects, including elevated levels of subtelomeric recombination and the formation of extrachromosomal and single-stranded telomeric DNA. Lengthening caused by some Rap1 binding site mutations can be suppressed by high-copy-number RAP1. Mutated telomeric repeats from a delayed elongation mutant are shown to be defective at regulating telomere length in cells with wild-type telomerase, indicating that the telomeric repeats are defective at telomere length regulation.

scholarly journals Evolution of sperm competition: Natural variation and genetic determinants of Caenorhabditis elegans sperm size

2018 ◽  
Author(s):  
Clotilde Gimond ◽  
Anne Vielle ◽  
Nuno Silva-Soares ◽  
Stefan Zdraljevic ◽  
Patrick T. McGrath ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Sperm Competition ◽  
Natural Variation ◽  
Competitive Ability ◽  
Molecular Mechanisms ◽  
Genetic Determinants ◽  
Heritable Variation ◽  
C Elegans ◽  
Male Sperm ◽  
Sperm Size

ABSTRACTSperm morphology is critical for sperm competition and thus for reproductive fitness. In the male-hermaphrodite nematode Caenorhabditis elegans, sperm size is a key feature of sperm competitive ability. Yet despite extensive research, the molecular mechanisms regulating C. elegans sperm size and the genetic basis underlying its natural variation remain unknown. Examining 97 genetically distinct C. elegans strains, we observe significant heritable variation in male sperm size but genome-wide association mapping did not yield any QTL (Quantitative Trait Loci). While we confirm larger male sperm to consistently outcompete smaller hermaphrodite sperm, we find natural variation in male sperm size to poorly predict male fertility and competitive ability. In addition, although hermaphrodite sperm size also shows significant natural variation, male and hermaphrodite sperm size do not correlate, implying a sex-specific genetic regulation of sperm size. To elucidate the molecular basis of intraspecific sperm size variation, we focused on recently diverged laboratory strains, which evolved extreme sperm size differences. Using mutants and quantitative complementation tests, we demonstrate that variation in the gene nurf-1 – previously shown to underlie the evolution of improved hermaphrodite reproduction – also explains the evolution of reduced male sperm size. This result illustrates how adaptive changes in C. elegans hermaphrodite function can cause the deterioration of a male-specific fitness trait due to a sexually antagonistic variant, representing an example of intralocus sexual conflict with resolution at the molecular level. Our results further provide first insights into the genetic determinants of C. elegans sperm size, pointing at an involvement of the NURF chromatin remodelling complex.

TheC. elegansmaternal-effect geneclk-2is essential for embryonic development, encodes a protein homologous to yeast Tel2p and affects telomere length

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 4045-4055 ◽  
Author(s):  
Claire Bénard ◽  
Brent McCright ◽  
Yue Zhang ◽  
Stephanie Felkai ◽  
Bernard Lakowski ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Telomere Length ◽  
Positional Cloning ◽  
Time Window ◽  
Temperature Sensitive ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
C Elegans ◽  
And Behavior

The Caenorhabditis elegans maternal-effect clk genes are involved in the temporal control of development and behavior. We report the genetic and molecular characterization of clk-2. A temperature-sensitive mutation in the gene clk-2 affects embryonic and post-embryonic development, reproduction, and rhythmic behaviors. Yet, virtually all phenotypes are fully maternally rescued. Embryonic development strictly requires the activity of maternal clk-2 during a narrow time window between oocyte maturation and the two- to four-cell embryonic stage. Positional cloning of clk-2 reveals that it encodes a protein homologous to S. cerevisiae Tel2p. In yeast, the gene TEL2 regulates telomere length and participates in gene silencing at subtelomeric regions. In C. elegans, clk-2 mutants have elongated telomeres, and clk-2 overexpression can lead to telomere shortening. Tel2p has been reported to bind to telomeric DNA repeats in vitro. However, we find that a functional CLK-2::GFP fusion protein is cytoplasmic in worms. We discuss how the phenotype of clk-2 mutants could be the result of altered patterns of gene expression.

scholarly journals Telomere length varies substantially between blood cell types in a reptile

2020 ◽  
Vol 7 (6) ◽  
pp. 192136 ◽  
Author(s):  
Mats Olsson ◽  
Nicholas J. Geraghty ◽  
Erik Wapstra ◽  
Mark Wilson
Keyword(s):  
Blood Cell ◽  
Telomere Length ◽  
Whole Blood ◽  
Phylogenetic Analyses ◽  
Natural Populations ◽  
Cell Types ◽  
Tissue Type ◽  
Telomeric Dna ◽  
Blood Cell Type ◽  
Widespread Phenomenon

Telomeres are repeat sequences of non-coding DNA-protein molecules that cap or intersperse metazoan chromosomes. Interest in telomeres has increased exponentially in recent years, to now include their ongoing dynamics and evolution within natural populations where individuals vary in telomere attributes. Phylogenetic analyses show profound differences in telomere length across non-model taxa. However, telomeres may also differ in length within individuals and between tissues. The latter becomes a potential source of error when researchers use different tissues for extracting DNA for telomere analysis and scientific inference. A commonly used tissue type for assessing telomere length is blood, a tissue that itself varies in terms of nuclear content among taxa, in particular to what degree their thrombocytes and red blood cells (RBCs) contain nuclei or not. Specifically, when RBCs lack nuclei, leucocytes become the main source of telomeric DNA. RBCs and leucocytes differ in lifespan and how long they have been exposed to ‘senescence' and erosion effects. We report on a study in which cells in whole blood from individual Australian painted dragon lizards ( Ctenophorus pictus ) were identified using flow cytometry and their telomere length simultaneously measured. Lymphocyte telomeres were on average 270% longer than RBC telomeres, and in azurophils (a reptilian monocyte), telomeres were more than 388% longer than those in RBCs. If this variation in telomere length among different blood cell types is a widespread phenomenon, and DNA for comparative telomere analyses are sourced from whole blood, evolutionary inference of telomere traits among taxa may be seriously complicated by the blood cell type comprising the main source of DNA.

scholarly journals Telomeric DNA sequences in beetle taxa vary with species richness

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniela Prušáková ◽  
Vratislav Peska ◽  
Stano Pekár ◽  
Michal Bubeník ◽  
Lukáš Čížek ◽  
...  
Keyword(s):  
Species Richness ◽  
Dna Sequences ◽  
Genome Instability ◽  
Telomeric Sequence ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
Common Pattern ◽  
Telomeric Sequences ◽  
Genomic Changes ◽  
Protective Structures

AbstractTelomeres are protective structures at the ends of eukaryotic chromosomes, and disruption of their nucleoprotein composition usually results in genome instability and cell death. Telomeric DNA sequences have generally been found to be exceptionally conserved in evolution, and the most common pattern of telomeric sequences across eukaryotes is (TxAyGz)n maintained by telomerase. However, telomerase-added DNA repeats in some insect taxa frequently vary, show unusual features, and can even be absent. It has been speculated about factors that might allow frequent changes in telomere composition in Insecta. Coleoptera (beetles) is the largest of all insect orders and based on previously available data, it seemed that the telomeric sequence of beetles varies to a great extent. We performed an extensive mapping of the (TTAGG)n sequence, the ancestral telomeric sequence in Insects, across the main branches of Coleoptera. Our study indicates that the (TTAGG)n sequence has been repeatedly or completely lost in more than half of the tested beetle superfamilies. Although the exact telomeric motif in most of the (TTAGG)n-negative beetles is unknown, we found that the (TTAGG)n sequence has been replaced by two alternative telomeric motifs, the (TCAGG)n and (TTAGGG)n, in at least three superfamilies of Coleoptera. The diversity of the telomeric motifs was positively related to the species richness of taxa, regardless of the age of the taxa. The presence/absence of the (TTAGG)n sequence highly varied within the Curculionoidea, Chrysomeloidea, and Staphylinoidea, which are the three most diverse superfamilies within Metazoa. Our data supports the hypothesis that telomere dysfunctions can initiate rapid genomic changes that lead to reproductive isolation and speciation.

scholarly journals Natural variation in plant telomere length is associated with flowering time

2021 ◽  
Author(s):  
Jae Young Choi ◽  
Liliia R Abdulkina ◽  
Jun Yin ◽  
Inna B Chastukhina ◽  
John T Lovell ◽  
...  
Keyword(s):  
Life History ◽  
Telomere Length ◽  
Flowering Time ◽  
Dna Sequences ◽  
Genome Wide Association Study ◽  
Genomic Analysis ◽  
Life History Strategies ◽  
Length Variation ◽  
Chromosomal Structure ◽  
Chromosome Integrity

Abstract Telomeres are highly repetitive DNA sequences found at the ends of chromosomes that protect the chromosomes from deterioration during cell division. Here, using whole genome re-sequencing and terminal restriction fragment assays, we found substantial natural intraspecific variation in telomere length in Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays). Genome-wide association study (GWAS) mapping in A. thaliana identified 13 regions with GWAS-significant associations underlying telomere length variation, including a region that harbors the telomerase reverse transcriptase (TERT) gene. Population genomic analysis provided evidence for a selective sweep at the TERT region associated with longer telomeres. We found that telomere length is negatively correlated with flowering time variation not only in A. thaliana, but also in maize and rice, indicating a link between life history traits and chromosome integrity. Our results point to several possible reasons for this correlation, including the possibility that longer telomeres may be more adaptive in plants that have faster developmental rates (and therefore flower earlier). Our work suggests that chromosomal structure itself might be an adaptive trait associated with plant life history strategies.

scholarly journals Telomere Length and Oxidative Stress and Its Relation with Metabolic Syndrome Components in the Aging

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 253
Author(s):  
Graciela Gavia-García ◽  
Juana Rosado-Pérez ◽  
Taide Laurita Arista-Ugalde ◽  
Itzen Aguiñiga-Sánchez ◽  
Edelmiro Santiago-Osorio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Metabolic Syndrome ◽  
Telomere Length ◽  
Scientific Evidence ◽  
Telomeric Dna ◽  
Biochemical Alterations ◽  
The Metabolic Syndrome ◽  
Age Related ◽  
And Function

A great amount of scientific evidence supports that Oxidative Stress (OxS) can contribute to telomeric attrition and also plays an important role in the development of certain age-related diseases, among them the metabolic syndrome (MetS), which is characterised by clinical and biochemical alterations such as obesity, dyslipidaemia, arterial hypertension, hyperglycaemia, and insulin resistance, all of which are considered as risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which are associated in turn with an increase of OxS. In this sense, we review scientific evidence that supports the association between OxS with telomere length (TL) dynamics and the relationship with MetS components in aging. It was analysed whether each MetS component affects the telomere length separately or if they all affect it together. Likewise, this review provides a summary of the structure and function of telomeres and telomerase, the mechanisms of telomeric DNA repair, how telomere length may influence the fate of cells or be linked to inflammation and the development of age-related diseases, and finally, how the lifestyles can affect telomere length.

scholarly journals Cdc13 N-Terminal Dimerization, DNA Binding, and Telomere Length Regulation

2010 ◽  
Vol 30 (22) ◽  
pp. 5325-5334 ◽  
Author(s):  
Meghan T. Mitchell ◽  
Jasmine S. Smith ◽  
Mark Mason ◽  
Sandy Harper ◽  
David W. Speicher ◽  
...  
Keyword(s):  
Dna Binding ◽  
Telomere Length ◽  
Functional Characterization ◽  
Point Mutations ◽  
Telomeric Dna ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Length Regulation ◽  
Telomere Length Regulation

ABSTRACT The essential yeast protein Cdc13 facilitates chromosome end replication by recruiting telomerase to telomeres, and together with its interacting partners Stn1 and Ten1, it protects chromosome ends from nucleolytic attack, thus contributing to genome integrity. Although Cdc13 has been studied extensively, the precise role of its N-terminal domain (Cdc13N) in telomere length regulation remains unclear. Here we present a structural, biochemical, and functional characterization of Cdc13N. The structure reveals that this domain comprises an oligonucleotide/oligosaccharide binding (OB) fold and is involved in Cdc13 dimerization. Biochemical data show that Cdc13N weakly binds long, single-stranded, telomeric DNA in a fashion that is directly dependent on domain oligomerization. When introduced into full-length Cdc13 in vivo, point mutations that prevented Cdc13N dimerization or DNA binding caused telomere shortening or lengthening, respectively. The multiple DNA binding domains and dimeric nature of Cdc13 offer unique insights into how it coordinates the recruitment and regulation of telomerase access to the telomeres.

scholarly journals Extensive genomic rearrangements mediated by repetitive sequences in plastomes of Medicago and its relatives

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shuang Wu ◽  
Jinyuan Chen ◽  
Ying Li ◽  
Ai Liu ◽  
Ao Li ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Genome Instability ◽  
Repetitive Sequences ◽  
Genomic Analysis ◽  
Genomic Rearrangements ◽  
Comparative Genomic ◽  
Length Variation ◽  
Substitution Rates ◽  
Repeat Content ◽  
Plastome Evolution

Abstract Background Although plastomes are highly conserved with respect to gene content and order in most photosynthetic angiosperms, extensive genomic rearrangements have been reported in Fabaceae, particularly within the inverted repeat lacking clade (IRLC) of Papilionoideae. Two hypotheses, i.e., the absence of the IR and the increased repeat content, have been proposed to affect the stability of plastomes. However, this is still unclear for the IRLC species. Here, we aimed to investigate the relationships between repeat content and the degree of genomic rearrangements in plastomes of Medicago and its relatives Trigonella and Melilotus, which are nested firmly within the IRLC. Results We detected abundant repetitive elements and extensive genomic rearrangements in the 75 newly assembled plastomes of 20 species, including gene loss, intron loss and gain, pseudogenization, tRNA duplication, inversion, and a second independent IR gain (IR ~ 15 kb in Melilotus dentata) in addition to the previous first reported cases in Medicago minima. We also conducted comparative genomic analysis to evaluate plastome evolution. Our results indicated that the overall repeat content is positively correlated with the degree of genomic rearrangements. Some of the genomic rearrangements were found to be directly linked with repetitive sequences. Tandem repeated sequences have been detected in the three genes with accelerated substitution rates (i.e., accD, clpP, and ycf1) and their length variation could be explained by the insertions of tandem repeats. The repeat contents of the three localized hypermutation regions around these three genes with accelerated substitution rates are also significantly higher than that of the remaining plastome sequences. Conclusions Our results suggest that IR reemergence in the IRLC species does not ensure their plastome stability. Instead, repeat-mediated illegitimate recombination is the major mechanism leading to genome instability, a pattern in agreement with recent findings in other angiosperm lineages. The plastome data generated herein provide valuable genomic resources for further investigating the plastome evolution in legumes.

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