scholarly journals Selfish chromosomal drive shapes recent centromeric histone evolution in monkeyflowers

2020 ◽  
Author(s):  
Findley R. Finseth ◽  
Thom C. Nelson ◽  
Lila Fishman
Keyword(s):  
Selective Sweep ◽  
Meiotic Drive ◽  
Mendelian Inheritance ◽  
Arms Race ◽  
The Past ◽  
Individual Fitness ◽  
Histone 3 ◽  
Quantitative Genetic ◽  
Stable Frequency ◽  
Protein Components

AbstractUnder the selfish centromere model, costs associated with female meiotic drive by centromeres select on interacting kinetochore proteins to restore Mendelian inheritance. We directly test this model in yellow monkeyflowers (Mimulus guttatus), which are polymorphic for a costly driving centromere (D). We show that the D haplotype is structurally and genetically distinct and swept to a high stable frequency within the past 1500 years. Quantitative genetic analyses reveal that variation in the strength of drive primarily depends on the identity of the non-D centromere, but also identified an unlinked modifier coincident with kinetochore protein Centromere-specific Histone 3 A (CenH3A). CenH3A has also experienced a recent (<1000 years) selective sweep in our focal population, consistent with ongoing interactions with D shaping its evolution. Together, our results demonstrate an active co-evolutionary arms race between the DNA and protein components of the meiotic machinery, with important consequences for individual fitness and molecular divergence.

scholarly journals Selfish chromosomal drive shapes recent centromeric histone evolution in monkeyflowers

PLoS Genetics ◽  
2021 ◽  
Vol 17 (4) ◽  
pp. e1009418
Author(s):  
Findley R. Finseth ◽  
Thomas C. Nelson ◽  
Lila Fishman
Keyword(s):  
Dna Sequences ◽  
Rapid Evolution ◽  
Mendelian Inheritance ◽  
Arms Race ◽  
Centromeric Dna ◽  
Kinetochore Protein ◽  
Individual Fitness ◽  
Histone 3 ◽  
Stable Frequency ◽  
Protein Components

Centromeres are essential mediators of chromosomal segregation, but both centromeric DNA sequences and associated kinetochore proteins are paradoxically diverse across species. The selfish centromere model explains rapid evolution by both components via an arms-race scenario: centromeric DNA variants drive by distorting chromosomal transmission in female meiosis and attendant fitness costs select on interacting proteins to restore Mendelian inheritance. Although it is clear than centromeres can drive and that drive often carries costs, female meiotic drive has not been directly linked to selection on kinetochore proteins in any natural system. Here, we test the selfish model of centromere evolution in a yellow monkeyflower (Mimulus guttatus) population polymorphic for a costly driving centromere (D). We show that theDhaplotype is structurally and genetically distinct and swept to a high stable frequency within the past 1500 years. We use quantitative genetic mapping to demonstrate that context-dependence in the strength of drive (from near-100%Dtransmission in interspecific hybrids to near-Mendelian in within-population crosses) primarily reflects variable vulnerability of the non-driving competitor chromosomes, but also map an unlinked modifier of drive coincident with kinetochore protein Centromere-specific Histone 3 A (CenH3A). Finally, CenH3A exhibits a recent (<1000 years) selective sweep in our focal population, implicating local interactions withDin ongoing adaptive evolution of this kinetochore protein. Together, our results demonstrate an active co-evolutionary arms race between DNA and protein components of the meiotic machinery inMimulus, with important consequences for individual fitness and molecular divergence.

scholarly journals Wolbachia -induced meiotic drive and feminization is associated with an independent occurrence of selective mitochondrial sweep in a butterfly

2017 ◽  
Vol 13 (5) ◽  
pp. 20170153 ◽  
Author(s):  
Mai Miyata ◽  
Tatsuro Konagaya ◽  
Kenji Yukuhiro ◽  
Masashi Nomura ◽  
Daisuke Kageyama
Keyword(s):  
Selective Sweep ◽  
Cytoplasmic Incompatibility ◽  
Meiotic Drive ◽  
Sequence Polymorphism ◽  
The Other ◽  
Considerable Proportion ◽  
Evolutionary Forces ◽  
Eurema Hecabe ◽  
Hybrid Introgression

Maternally inherited Wolbachia endosymbionts manipulate arthropod reproduction in various ways. In the butterfly Eurema mandarina , a cytoplasmic incompatibility-inducing Wolbachia strain w CI and the associated mtDNA haplotypes are known to originate from the sister species Eurema hecabe , which offered a good case study for microbe-mediated hybrid introgression. Besides w CI, some females with the Z0 karyotype harbour a distinct Wolbachia strain w Fem, which causes all-female production by meiotic drive and feminization. We report that a considerable proportion of E. mandarina females (65.7%) were infected with both w CI and w Fem (CF) on Tanegashima Island. While females singly infected with w CI (C) produced offspring at a 1 : 1 sex ratio, CF females produced only females. Although Z-linked sequence polymorphism showed no signs of divergence between C and CF females, mtDNA split into two discrete clades; one consisted of C females and the other CF females, both of which formed a clade with E. hecabe but not with uninfected E. mandarina . This suggests that CF matrilines also, but independently, experienced a selective sweep after hybrid introgression from E. hecabe . Distinct evolutionary forces were suggested to have caused C and CF matrilines to diverge, which would be irreversible because of the particular phenotype of w Fem.

scholarly journals College Athletics Spending: Principals and Agents v. Arms Race

2016 ◽  
Vol 2 (1) ◽  
pp. 119 ◽  
Author(s):  
Rodney Fort
Keyword(s):  
College Athletics ◽  
Athletic Directors ◽  
Arms Race ◽  
Policy Implications ◽  
University Administrators ◽  
Athletic Department ◽  
The Past ◽  
Level Data ◽  
The University ◽  
Budgeting Process

It is widely held that collegiate athletic directors are trapped in an expenditure arms race.  But the arms race explanation completely omits the actual consideration of the university budgeting process.  In its place, the arms race logic imposes strained assumptions about the cooperative setting and the naïveté of university administrators, along with a curious distinction of one type of revenue to reach its conclusions.  And the interpretation of the data on spending and benefits from college sports has not been done particularly well in the past. This paper presents an alternative principal-agent explanation that is based on the observed actual financial (budget) relationship between university administrators and their athletic department and consistent with the entirety of the aggregate-level data on college athletics finance.  Empirically discerning between the two models is crucial since each generates decidedly different policy implications.

Technology Transfer

2011 ◽  
pp. 100-113
Author(s):  
Russ Lea
Keyword(s):  
Technology Transfer ◽  
Public Good ◽  
Public Funding ◽  
Arms Race ◽  
The Public ◽  
Economic Competitiveness ◽  
The Past ◽  
Private And Public ◽  
Technology Parks ◽  
Academic Earmarking

In the past three decades, economic competitiveness has morphed from an international concern (e.g. outcompete Japan) to a regional concern (e.g. knowledge clusters) to one where individual universities are in an “arms race” with each other for private and public funding (including licensing royalties, retaining star faculty, pursuing academic earmarking, developing technology parks and incubators, etc.). The greatest benefit that Bayh-Dole afforded universities, namely, to promote the utilization of their research for the public good, sometimes seems distant to the perceived objectives whereby universities attempt to maximize their own resources, including commercialization profits from faculty innovations that are ultimately transferred to the economy.

Sex-ratio meiotic drive in Drosophila simulans: cellular mechanism, candidate genes and evolution

2006 ◽  
Vol 34 (4) ◽  
pp. 562-565 ◽  
Author(s):  
C. Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
X Chromosome ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Female Offspring ◽  
Drosophila Simulans ◽  
X Chromosomes ◽  
Individual Fitness ◽  
Primary Sex Ratio ◽  
Intragenomic Conflict

The sex-ratio trait, reported in a dozen Drosophila species, is a type of naturally occurring meiotic drive in which the driving elements are located on the X chromosome. Typically, as the result of a shortage of Y-bearing spermatozoa, males carrying a sex-ratio X chromosome produce a large excess of female offspring. The presence of sex-ratio chromosomes in a species can have considerable evolutionary consequences, because they can affect individual fitness and trigger extended intragenomic conflict. Here, I present the main results of the study performed in Drosophila simulans. In this species, the loss of Y-bearing spermatozoa is related to the inability of the Y chromosome sister-chromatids to separate properly during meiosis II. Fine genetic mapping has shown that the primary sex-ratio locus on the X chromosome contains two distorter elements acting synergistically, both of which are required for drive expression. One element has been genetically mapped to a tandem duplication. To infer the natural history of the trait, the pattern of DNA sequence polymorphism in the surrounding chromosomal region is being analysed in natural populations of D. simulans harbouring sex-ratio X chromosomes. Initial results have revealed the recent spread of a distorter allele.

scholarly journals Tiptoeing to chromosome tips: facts, promises and perils of today's human telomere biology

2002 ◽  
Vol 357 (1420) ◽  
pp. 545-562 ◽  
Author(s):  
J. Fajkus ◽  
M. Šimíčková ◽  
J. Maláska
Keyword(s):  
Reverse Transcriptase ◽  
Cancer Cells ◽  
Cancer Diagnostics ◽  
Structure And Function ◽  
The Past ◽  
Descriptive Approach ◽  
Human Telomere ◽  
Telomere Biology ◽  
Protein Components ◽  
And Function

The past decade has witnessed an explosion of knowledge concerning the structure and function of chromosome terminal structures—telomeres. Today's telomere research has advanced from a pure descriptive approach of DNA and protein components to an elementary understanding of telomere metabolism, and now to promising applications in medicine. These applications include ‘passive’ ones, among which the use of analysis of telomeres and telomerase (a cellular reverse transcriptase that synthesizes telomeres) for cancer diagnostics is the best known. The ‘active’ applications involve targeted downregulation or upregulation of telomere synthesis, either to mortalize immortal cancer cells, or to rejuvenate mortal somatic cells and tissues for cellular transplantations, respectively. This article reviews the basic data on structure and function of human telomeres and telomerase, as well as both passive and active applications of human telomere biology.

scholarly journals The Mitochondrial Aminoacyl tRNA Synthetases: Genes and Syndromes

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Daria Diodato ◽  
Daniele Ghezzi ◽  
Valeria Tiranti
Keyword(s):  
Mitochondrial Dna ◽  
Respiratory Chain ◽  
Current Knowledge ◽  
Mitochondrial Respiratory Chain ◽  
Trna Synthetases ◽  
The Past ◽  
Aminoacyl Trna Synthetases ◽  
Clinical Presentations ◽  
Mtdna Replication ◽  
Protein Components

Mitochondrial respiratory chain (RC) disorders are a group of genetically and clinically heterogeneous diseases. This is because protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis and maintenance of mitochondria, including mitochondrial DNA (mtDNA) replication, transcription, and translation, require nuclear-encoded genes. In the past decade, a growing number of syndromes associated with dysfunction of mtDNA translation have been reported. This paper reviews the current knowledge of mutations affecting mitochondrial aminoacyl tRNAs synthetases and their role in the pathogenic mechanisms underlying the different clinical presentations.

scholarly journals Mechanism of semen liquefaction and its potential for a novel non-hormonal contraception†

2020 ◽  
Vol 103 (2) ◽  
pp. 411-426
Author(s):  
Prashanth Anamthathmakula ◽  
Wipawee Winuthayanon
Keyword(s):  
Serine Proteases ◽  
Reproductive Tract ◽  
Hormonal Contraception ◽  
Female Reproductive Tract ◽  
Fallopian Tubes ◽  
Contraceptive Methods ◽  
The Past ◽  
Liquefaction Process ◽  
Protein Components ◽  
Prime Target

Abstract Semen liquefaction is a proteolytic process where a gel-like ejaculated semen becomes watery due to the enzymatic activity of prostate-derived serine proteases in the female reproductive tract. The liquefaction process is crucial for the sperm to gain their motility and successful transport to the fertilization site in Fallopian tubes (or oviducts in animals). Hyperviscous semen or failure in liquefaction is one of the causes of male infertility. Therefore, the biochemical inhibition of serine proteases in the female reproductive tract after ejaculation is a prime target for novel contraceptive development. Herein, we will discuss protein components in the ejaculates responsible for semen liquefaction and any developments of contraceptive methods in the past that involve the liquefaction process.

scholarly journals Assuring Assured Retaliation: China's Nuclear Posture and U.S.-China Strategic Stability

2015 ◽  
Vol 40 (2) ◽  
pp. 7-50 ◽  
Author(s):  
Fiona S. Cunningham ◽  
M. Taylor Fravel
Keyword(s):  
United States ◽  
Nuclear Weapons ◽  
Critical Factor ◽  
The United States ◽  
Arms Race ◽  
Nuclear Forces ◽  
Nuclear Strategy ◽  
The Past ◽  
Strategic Stability ◽  
Small Force

Whether China will abandon its long-standing nuclear strategy of assured retaliation for a first-use posture will be a critical factor in future U.S.-China strategic stability. In the past decade, advances in U.S. strategic capabilities, especially missile defenses and enhanced long-range conventional strike capacity, could undermine China's nuclear retaliatory capability, which is based on a relatively small force and second-strike posture. An exhaustive review of Chinese writings on military affairs indicates, however, that China is unlikely to abandon its current nuclear strategy of assured retaliation. Instead, China will modestly expand its arsenal, increase the sophistication of its forces, and allow limited ambiguity regarding its pledge not to use nuclear weapons first. This limited ambiguity allows China to use the threat of nuclear retaliation to deter a conventional attack on its nuclear arsenal, without significantly increasing the size of its nuclear forces and triggering a costly arms race. Nevertheless, China's effort to maintain its strategy of assured retaliation while avoiding an arms race could backfire. Those efforts increase the risk that nuclear weapons could be used in a crisis between the United States and China, even though China views this possibility as much less likely than the United States does.

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