scholarly journals Maize centromeric chromatin scales with changes in genome size

Genetics ◽  
2021 ◽  
Vol 217 (4) ◽  
Author(s):  
Na Wang ◽  
Jianing Liu ◽  
William A Ricci ◽  
Jonathan I Gent ◽  
R Kelly Dawe
Keyword(s):  
Genome Size ◽  
Cell Size ◽  
Histone H3 ◽  
Limiting Factors ◽  
Positive Relationships ◽  
Satellite Sequence ◽  
Centromeric Chromatin ◽  
Protein Levels ◽  
Centromeric Satellite

Abstract Centromeres are defined by the location of Centromeric Histone H3 (CENP-A/CENH3) which interacts with DNA to define the locations and sizes of functional centromeres. An analysis of 26 maize genomes including 110 fully assembled centromeric regions revealed positive relationships between centromere size and genome size. These effects are independent of variation in the amounts of the major centromeric satellite sequence CentC. We also backcrossed known centromeres into two different lines with larger genomes and observed consistent increases in functional centromere sizes for multiple centromeres. Although changes in centromere size involve changes in bound CENH3, we could not mimic the effect by overexpressing CENH3 by threefold. Literature from other fields demonstrate that changes in genome size affect protein levels, organelle size and cell size. Our data demonstrate that centromere size is among these scalable features, and that multiple limiting factors together contribute to a stable centromere size equilibrium.

scholarly journals Maize centromeric chromatin scales with changes in genome size

2020 ◽  
Author(s):  
Na Wang ◽  
Jianing Liu ◽  
William A. Ricci ◽  
Jonathan I. Gent ◽  
R. Kelly Dawe
Keyword(s):  
Genome Size ◽  
Cell Size ◽  
Histone H3 ◽  
Limiting Factors ◽  
Positive Relationships ◽  
Satellite Sequence ◽  
Centromeric Chromatin ◽  
Protein Levels ◽  
Centromeric Satellite

AbstractCentromeres are defined by the location of Centromeric Histone H3 (CENP-A/CENH3) which interacts with DNA to define the locations and sizes of functional centromeres. An analysis of 26 maize genomes including 110 fully assembled centromeric regions revealed positive relationships between centromere size and genome size. These effects are independent of variation in the amounts of the major centromeric satellite sequence CentC. We also backcrossed known centromeres into two different lines with larger genomes and observed consistent increases in functional centromere sizes for multiple centromeres. Although changes in centromere size involve changes in bound CENH3, we could not mimic the effect by overexpressing CENH3 by threefold. Literature from other fields demonstrate that changes in genome size affect protein levels, organelle size and cell size. Our data demonstrate that centromere size is among these scalable features, and that multiple limiting factors together contribute to a stable centromere size equilibrium.

scholarly journals Genome size drives morphological evolution in organ-specific ways

2021 ◽  
Author(s):  
Michael W Itgen ◽  
Dustin S Siegel ◽  
Stanley K Sessions ◽  
Rachel Lockridge Mueller
Keyword(s):  
Body Size ◽  
Genome Size ◽  
Cell Size ◽  
Structural Changes ◽  
Morphological Evolution ◽  
Empty Space ◽  
Developmental Rate ◽  
Cellular Interactions ◽  
Structure Changes ◽  
Organ Specific

Morphogenesis is an emergent property of biochemical and cellular interactions during development. Genome size and the correlated trait of cell size can influence these interactions through its effects on developmental rate and tissue geometry, ultimately driving the evolution of morphology. We tested the effects of genome size and body size evolution on heart and liver morphology using nine species of the salamander genus Plethodon (genome sizes 29.3-67 Gb). Our results show that whole organ size is determined by body size, whereas tissue structure changes dramatically with evolutionary increases in genome size. In the heart, increased genome size is correlated with a reduction of myocardia in the ventricle, yielding proportionally less force-producing mass and more empty space. In the liver, increased genome size is correlated with fewer and larger vascular structures, positioning hepatocytes farther from the circulatory vessels that transport key metabolites. Although these structural changes should have obvious impacts on organ function, their effects on organismal performance and fitness are likely negligible because low metabolic rates in salamanders relax selective pressure on key metabolic organ performance. Overall, this study reveals the effects of large genome and cell size on the developmental systems producing the heart and liver.

Post-ovulatory ageing of mouse oocytes affects the distribution of specific spindle-associated proteins and Akt expression levels

2014 ◽  
Vol 26 (4) ◽  
pp. 562 ◽  
Author(s):  
Sandra Cecconi ◽  
Gianna Rossi ◽  
Hamid Deldar ◽  
Valerio Cellini ◽  
Felice Patacchiola ◽  
...  
Keyword(s):  
Histone H3 ◽  
Meiotic Spindle ◽  
Post Translational Modifications ◽  
Expression Levels ◽  
Acetylated Tubulin ◽  
Protein Levels ◽  
Histone 3 ◽  
Phosphorylated Akt ◽  
Associated Proteins

The aim of this study has been to determine the effects of in vivo post-ovulatory ageing (POA) on the distribution of spindle-associated proteins, histone H3/H4 post-translational modifications and on v-akt murine thymoma viral oncogene homolog 1 (Akt) expression levels. To this end, oocytes were retrieved 13, 29 and 33 h after human chorionic gonadotrophin (hCG) treatment. The presence and distribution at the meiotic spindle of acetylated tubulin, γ-tubulin, polo kinase-1 and Ser473/Thr308 phosphorylated Akt (pAkt) as well as histone H3 and H4 acetylation and phosphorylation levels were assayed via immunofluorescence. Akt expression levels were determined via reverse transcription–polymerase chain reaction and western blotting analyses. Spindles from oocytes recovered 13 h and 29 h after hCG treatment showed similar levels of acetylated tubulin but ageing induced: (1) translocation of γ-tubulin from spindle poles to microtubules, (2) absence of Thr308- and Ser473-pAkt in 76% and 30% of oocytes, respectively, and (3) a significant reduction in phosphorylation levels of serine 10 on histone 3. At 29 h, a significant decrease in Akt mRNA, but not in pAkt or Akt protein levels, was recorded. By contrast, protein content significantly decreased 33 h after hCG. We conclude that POA impairs oocyte viability and fertilisability by altering the expression levels and spindle distribution of proteins that are implicated in cell survival and chromosome segregation. Together, these events could play a role in oocyte apoptosis.

scholarly journals How small and constrained is the genome size of angiosperm woody species

2015 ◽  
Vol 64 (1-6) ◽  
pp. 20-32 ◽  
Author(s):  
Deepak Ohri
Keyword(s):  
Genome Size ◽  
Cell Size ◽  
Large Population ◽  
Size Variation ◽  
Woody Species ◽  
Herbaceous Species ◽  
Wood Fibers ◽  
Genome Size Variation ◽  
Woody Habit ◽  
Taxonomic Groups

AbstractAngiosperm hardwood species are generally considered to show an average smaller genome size with a narrow range of variation than their herbaceous counterparts. Various explanations pertaining to limitations of cell size exerted by wood fibers, the requirement of smaller stomata, longer generation time, large population size, etc., have been put forward to account for their small and constrained genome size. Yet studies done in the past several years show that genomically as well as evolutionarily, hardwoods are as diverse and active as their herbaceous counterparts. This is entirely supported by the presence of well developed inter and intraspecific polyploid series and natural triploidy in many genera. Polyploidy, in some instances has been shown to confer adaptability to arid and salt stress conditions and in colonization of new areas. Moreover, hardwoods also show reasonable amenability to the induced polyploidy which abruptly changes the balance between nuclear and cell size. Polyploidy has been induced in many hardwoods to restore fertility in interspecific hybrids and for the production of triploids.Furthermore, some cases studied show that genome size variation in hardwoods can be as variable as that of herbaceous species. Genome size has been shown to vary remarkably both at homoploid level as well as by polyploidy in certain genera. In the same way, the genome size is not correlated with the habit in certain groups having both herbaceous and woody taxa. This point is further proved by the presence of secondary and insular woody habit in certain cases where either the transition to woodiness is not followed by any diminution in the genome size, or the genome size of insular woody species may be even more than that of the congeneric herbaceous species. This shows that woody habit does not by itself put any constraints on the genome size either at homoploid or at polyploidy levels. The genome size in fact, not only varies significantly in many congeneric woody species but also may not show any correlation with the habit when woody and herbaceous species are compared in some narrow taxonomic groups studied.

scholarly journals Cell Cycle-dependent Expression and Nucleolar Localization of hCAP-H

2001 ◽  
Vol 12 (11) ◽  
pp. 3527-3537 ◽  
Author(s):  
Olga A. Cabello ◽  
Elena Eliseeva ◽  
WeiGong He ◽  
Hagop Youssoufian ◽  
Sharon E. Plon ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Histone H3 ◽  
Chromosome Condensation ◽  
Nucleolar Localization ◽  
Mitotic Chromosomes ◽  
Proliferating Cells ◽  
Protein Levels ◽  
Sister Chromatids ◽  
H3 Phosphorylation ◽  
Histone H3 Phosphorylation

Condensin is a conserved 13S heteropentamer composed of two nonidentical structural maintenance of chromosome (SMC) family proteins, in Xenopus XCAP-C and XCAP-E, and three regulatory subunits, XCAP-D2, XCAP-G, and XCAP-H. Both biochemical and genetic analyses have demonstrated an essential role for the 13S condensin complex in mitotic chromosome condensation. Further, a potential requirement for condensin in completion of chromatid arm separation in early anaphase is demonstrated by the mutational phenotypes of the Drosophila homologues ofXCAP-H, barren and XCAP-C,DmSMC4. In this study we have investigated the expression and subcellular distribution of hCAP-H, the human homolog of XCAP-H, in order to better understand its cellular functions. Transcription of hCAP-H was restricted to proliferating cells with highest expression during the G2 phase of the cell cycle. In contrast, cellular hCAP-H protein levels were constant throughout the cell cycle. hCAP-H was found to be associated with mitotic chromosomes exhibiting a nonuniform but symmetric distribution along sister chromatids. The symmetry of hCAP-H association with sister chromatids suggests that there are sequence-dependent domains of condensin aggregation. During interphase hCAP-H, -C, and -E, have distinct punctate nucleolar localization, suggesting that condensin may associate with and modulate the conformation and function of rDNA. hCAP-H association with condensed chromatin was not observed in the early phase of chromosome condensation when histone H3 phosphorylation has already taken place. This finding is consistent with the hypothesis that histone H3 phosphorylation precedes condensin-mediated condensation.

scholarly journals Genome size is a strong predictor of cell size and stomatal density in angiosperms

2008 ◽  
Vol 179 (4) ◽  
pp. 975-986 ◽  
Author(s):  
Jeremy M. Beaulieu ◽  
Ilia J. Leitch ◽  
Sunil Patel ◽  
Arjun Pendharkar ◽  
Charles A. Knight
Keyword(s):  
Genome Size ◽  
Cell Size ◽  
Stomatal Density ◽  
Strong Predictor

Aging alters histone H3 lysine 4 methylation in mouse germinal vesicle stage oocytes

2015 ◽  
Vol 27 (2) ◽  
pp. 419 ◽  
Author(s):  
Gen-Bao Shao ◽  
Jie Wang ◽  
Liu-Ping Zhang ◽  
Chao-Yang Wu ◽  
Jie Jin ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Histone H3 ◽  
Germinal Vesicle ◽  
Retinol Binding Protein ◽  
Oocyte Competence ◽  
Protein Levels ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Maternal Aging ◽  
Old Mice

Decreasing oocyte competence with maternal aging is a major factor in mammalian infertility. One of the factors contributing to this infertility is changes to chromatin modifications, such as histone acetylation in old MII stage oocytes. Recent studies indicate that changes in histone acetylation at MII arise at the germinal vesicle (GV) stage. We hypothesised that histone methylation could also change in old GV oocytes. To test this hypothesis, we examined mono-, di- and trimethylation of histone H3 lysine 4 (H3K4 me1, me2 and me3, respectively) in young and older oocytes from 6–8- and 42–44-week-old mice, respectively. We found that H3K4 me2 and me3 decreased in older compared with young GV oocytes (100% vs 81% and 100% vs 87%, respectively; P < 0.05). H3K4 me2 later increased in older MII oocytes (21% vs 56%; P < 0.05). We also examined the expression of genes encoding the H3K4 demethylases lysine (K)-specific demethylase 1A (Kdm1a) and retinol binding protein 2 (Rbp2). Expression of Kdm1a increased at both the mRNA and protein levels in older GV oocytes, but decreased in older MII oocytes (P < 0.05), and was negatively correlated with H3K4 me2 levels. Conversely, expression of Rbp2 mRNA and protein decreased in older GV oocytes (P < 0.05), and this was not correlated with H3K4 me3 levels. Finally, we showed that inhibition of Kdm1a of older oocytes at the GV stage restored levels of H3K4 me2 at the MII stage to those seen in ‘young’ oocytes (41% vs 38%; P > 0.05). These results suggest that changes in expression of H3K4 me2 and Kdm1a in older GV oocytes may represent a molecular mechanism underlying human infertility caused by aging.

scholarly journals CENP-A nucleosome—a chromatin-embedded pedestal for the centromere: lessons learned from structural biology

2020 ◽  
Vol 64 (2) ◽  
pp. 205-221
Author(s):  
Ahmad Ali-Ahmad ◽  
Nikolina Sekulić
Keyword(s):  
Cell Division ◽  
Structural Biology ◽  
Histone H3 ◽  
Lessons Learned ◽  
Centromeric Chromatin ◽  
Centromere Proteins ◽  
Molecular Determinants ◽  
Histone H3 Variant ◽  
Segregation Of Chromosomes

Abstract The centromere is a chromosome locus that directs equal segregation of chromosomes during cell division. A nucleosome containing the histone H3 variant CENP-A epigenetically defines the centromere. Here, we summarize findings from recent structural biology studies, including several CryoEM structures, that contributed to elucidate specific features of the CENP-A nucleosome and molecular determinants of its interactions with CENP-C and CENP-N, the only two centromere proteins that directly bind to it. Based on those findings, we propose a role of the CENP-A nucleosome in the organization of centromeric chromatin beyond binding centromeric proteins.

scholarly journals Subunit interactions and arrangements in the fission yeast Mis16–Mis18–Mis19 complex

2019 ◽  
Vol 2 (4) ◽  
pp. e201900408 ◽  
Author(s):  
Melanie Korntner-Vetter ◽  
Stéphane Lefèvre ◽  
Xiao-Wen Hu ◽  
Roger George ◽  
Martin R Singleton
Keyword(s):  
Cell Cycle ◽  
Binding Site ◽  
Fission Yeast ◽  
Histone H3 ◽  
Histone H4 ◽  
Subunit Interactions ◽  
Centromeric Chromatin ◽  
Partner Protein ◽  
Histone H3 Variant

Centromeric chromatin in fission yeast is distinguished by the presence of nucleosomes containing the histone H3 variant Cnp1CENP-A. Cell cycle–specific deposition of Cnp1 requires the Mis16–Mis18–Mis19 complex, which is thought to direct recruitment of Scm3-chaperoned Cnp1/histone H4 dimers to DNA. Here, we present the structure of the essential Mis18 partner protein Mis19 and describe its interaction with Mis16, revealing a bipartite-binding site. We provide data on the stoichiometry and overall architecture of the complex and provide detailed insights into the Mis18–Mis19 interface.

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