scholarly journals Theoretical consequences of the Mutagenic Chain Reaction for manipulating natural populations

2015 ◽  
Author(s):  
Robert Unckless ◽  
Philipp Messer ◽  
Andrew Clark
Keyword(s):  
Critical Point ◽  
High Frequency ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Fitness Cost ◽  
Chain Reaction ◽  
Internal Equilibrium ◽  
Rapid Fixation ◽  
Genetic Technologies ◽  
Mutagenic Chain Reaction

The use of recombinant genetic technologies for population manipulation has mostly remained an abstract idea due to the lack of a suitable means to drive novel gene constructs to high frequency in populations. Recently Gantz and Bier showed that the use of CRISPR/Cas9 technology could provide an artificial drive mechanism, the so-called Mutagenic Chain Reaction (MCR), which could lead to rapid fixation of even a deleterious introduced allele. We establish the equivalence of this system to models of meiotic drive and review the results of simple models showing that, when there is a fitness cost to the MCR allele, an internal equilibrium exists that is usually unstable. Introductions must be at a frequency above this critical point for the successful invasion of the MCR allele. These modeling results have important implications for application of MCR in natural populations.

scholarly journals Modeling the Manipulation of Natural Populations by the Mutagenic Chain Reaction

Genetics ◽  
2015 ◽  
Vol 201 (2) ◽  
pp. 425-431 ◽  
Author(s):  
Robert L. Unckless ◽  
Philipp W. Messer ◽  
Tim Connallon ◽  
Andrew G. Clark
Keyword(s):  
Natural Populations ◽  
Chain Reaction ◽  
Mutagenic Chain Reaction

scholarly journals The Sex-Ratio Trait in Drosophila simulans: Genetic Analysis of Distortion and Suppression

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 635-642 ◽  
Author(s):  
Michel Cazemajor ◽  
Claudie Landré ◽  
Catherine Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
Genetic Analysis ◽  
High Frequency ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Drosophila Simulans ◽  
Standard Strain ◽  
Large Excess ◽  
X Chromosomes ◽  
Naturally Occurring

The sex-ratio trait described in several Drosophila species is a type of naturally occurring X-linked meiotic drive that causes males bearing a sex-ratio  X chromosome to produce progenies with a large excess of females. We have previously reported the occurrence of sex-ratio X chromosomes in Drosophila simulans. In this species, because of the co-occurrence of drive suppressors, the natural populations and the derived laboratory strains show an equal sex-ratio even when sex-ratio X chromosomes are present at a high frequency. The presence of sex-ratio X chromosomes is established via crosses with a standard strain that is devoid of drive suppressors. In this article, we show first that the sex-ratio trait in D. simulans results from the action of several X-linked loci. Second we describe drive suppressors on each major autosome as well as on the Y chromosome. The Y-linked factors suppress the drive partially whereas the autosomal suppression can be complete.

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

scholarly journals Occurrence of abortions induced by Neospora caninum in dairy cattle from Santa Catarina, southern Brazil

2017 ◽  
Vol 26 (3) ◽  
pp. 292-298 ◽  
Author(s):  
Cesar Augusto Barbosa de Macedo ◽  
Madlaine Frigo Silveira Barbosa de Macedo ◽  
Ana Carolina Miura ◽  
Alessandra Taroda ◽  
Sergio Tosi Cardim ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
High Frequency ◽  
Neospora Caninum ◽  
Enzyme Linked Immunosorbent Assay ◽  
Southern Brazil ◽  
Chain Reaction ◽  
Santa Catarina ◽  
Tissue Samples ◽  
Polymerase Chain

Abstract The aim of the present study was to investigate the occurrence of N. caninum associated with abortions of dairy cattle from Santa Catarina state, southern Brazil by using enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), and polymerase chain reaction (PCR). Blood from dairy cows that aborted along with intrathoracic fluid and tissue samples (brain, heart, liver, and lung) from their fetuses were collected and used for serology; PCR, histopathological, and immunohistochemistry (IHC) evaluations were also conducted. Twenty-one cows (51.2%) out of 41, and eight fetuses (26.7%) out of 30 were ELISA (HerdCheck, IDEXX) positive for N. caninum. Dams > 36 months of age had a higher risk of being serum positive than younger animals. PCR and IHC revealed that 38.8% (14/36) and 25.0% (9/36) of the fetuses were positive for N. caninum, respectively for each of the tests. Seropositive cows had a higher frequency of fetuses that were also positive by either intrathoracic fluid, PCR, or IHC. In summary, the present study observed a high frequency of N. caninum in abortions from dairy cows from southern Brazil, with a higher N. caninum prevalence found in cows that were older than 36 months. In addition, serology, PCR, and IHC should be used all together for better diagnosis of neosporosis in cattle.

scholarly journals A pooled sequencing approach identifies a candidate meiotic driver in Drosophila

2017 ◽  
Author(s):  
Kevin H-C Wei ◽  
Hemakumar M. Reddy ◽  
Chandramouli Rathnam ◽  
Jimin Lee ◽  
Deanna Lin ◽  
...  
Keyword(s):  
Telomere Length ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Length Variation ◽  
Sequence Evolution ◽  
Nucleotide Polymorphisms ◽  
Mendelian Segregation ◽  
Transmission Frequency ◽  
Multiple Observations ◽  
Telomere Sequence

AbstractMeiotic drive occurs when a selfish element increases its transmission frequency above the Mendelian ratio by hijacking the asymmetric divisions of female meiosis. Meiotic drive causes genomic conflict and potentially has a major impact on genome evolution, but only a few drive loci of large effect have been described. New methods to reliably detect meiotic drive are therefore needed, particularly for discovering moderate-strength drivers that are likely to be more prevalent in natural populations than strong drivers. Here we report an efficient method that uses sequencing of large pools of backcross (BC1) progeny to test for deviations from Mendelian segregation genome-wide of single-nucleotide polymorphisms (SNPs) that distinguish the parental strains. We show that meiotic drive can be detected by a characteristic pattern of decay in distortion of SNP frequencies, caused by recombination unlinking the driver from distal loci. We further show that control crosses allow allele-frequency distortion caused by meiotic drive to be distinguished from distortion resulting from developmental effects. We used this approach to test whether chromosomes with extreme telomere-length differences segregate at Mendelian ratios, as telomeric regions are a potential hotspot for meiotic drive due to their roles in meiotic segregation and multiple observations of high rates of telomere sequence evolution. Using four different pairings of long and short telomere strains, we find no evidence that extreme telomere-length variation causes meiotic drive in Drosophila. However, we identify one candidate meiotic driver in a centromere-linked region that shows an ~8% increase in transmission frequency, corresponding to a ~54:46 segregation ratio. Our results show that candidate meiotic drivers of moderate strength can be readily detected and localized in pools of F1 progeny.

scholarly journals Cytogenetic differentiation between Palearctic and Nearctic populations of Chironomus plumosus L. (Diptera, Chironomidae)

Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 797-815 ◽  
Author(s):  
Malcolm G Butler ◽  
Iya I Kiknadze ◽  
Veronica V Golygina ◽  
Jon Martin ◽  
Albina G Istomina ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
High Frequency ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Chironomus Plumosus ◽  
Chromosomal Banding ◽  
Great Divergence ◽  
Holarctic Species

Macrogeographic patterns of polytene chromosomal banding sequences were studied in natural populations of the Holarctic species Chironomus plumosus. Of the 31 inversion sequences now known, 16 are endemic to the Palearctic, 7 are endemic to the Nearctic, and 8 are Holarctic sequences common to both zoogeographic zones. Differences in the sets of inversion sequences found on each continent, plus differing frequencies of Holarctic sequences, result in great overall divergence of karyotypes on the two continents. The karyotype of Nearctic C. plumosus differs from that of Palearctic populations primarily by the presence of a homozygous Nearctic sequence in arm A (n'plu A9), along with fixation (h'plu C2, h'plu E2, and h'plu F1), or high frequency (h'plu D2), of Holarctic sequences which are present but less frequent in the Palearctic. Although long continental isolation has led to great divergence of karyotypes on opposite sides of the Atlantic Ocean, all populations of C. plumosus show sufficient cytogenetic similarity to constitute a single Holarctic species.Key words: karyotype, inversion polymorphism, cytogenetic distances, Chironomus.

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.

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