The Drosophila Y Chromosome Affects Heterochromatin Integrity Genome-Wide

Brown, Emily J.; Nguyen, Alison H.; Bachtrog, Doris

doi:10.1093/molbev/msaa082

Cited by 57 publications

(44 citation statements)

References 76 publications

(107 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recombination suppression also leads to an accumulation of repetitive DNA in the Y and W chromosomes [14, 15], and recent evidence has shown that repetitive DNA is disproportionally de-repressed (and hence mis-expressed) during ageing in Drosophila melanogaster . Moreover, this phenomenon influences chromatin integrity and gene expression profiles genome-wide [16], and is more acute in old males than in old females [17, 18]. Therefore, in D. melanogaster there is solid evidence of substantial “toxic Y” effects, via both the accumulation of deleterious mutations and repetitive DNA elements, resulting in increased mortality of the heterogametic sex [13, 14].…”

Section: Mainmentioning

confidence: 99%

Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

Sultanova

Downing

Carazo

2020

Preprint

View full text Add to dashboard Cite

26Sex-specific lifespans are ubiquitous across the tree of life and exhibit broad taxonomic 27 patterns that remain a puzzle, such as males living longer than females in birds and vice versa 28 in mammals. The prevailing "unguarded-X" hypothesis (UXh) explains this by differential 29 expression of recessive mutations in the X/Z chromosome of the heterogametic sex (e.g., 30females in birds and males in mammals), but has only received indirect support to date. An 31 alternative hypothesis is that the accumulation of deleterious mutations and repetitive 32 elements on the Y/W chromosome might lower the survival of the heterogametic sex ("toxic 33 Y" hypothesis). Here, we report lower survival of the heterogametic relative to the 34 homogametic sex across 138 species of birds, mammals, reptiles and amphibians, as expected 35 if sex chromosomes shape sex-specific lifespans. We then analysed bird and mammal 36 karyotypes and found that the relative sizes of the X and Z chromosomes are not associated 37 with sex-specific lifespans, contrary to UXh predictions. In contrast, we found that Y size 38 correlates negatively with male survival in mammals, where toxic Y effects are expected to be 39 particularly strong. This suggests that small Y chromosomes benefit male lifespans. Our 40 results confirm the role of sex chromosomes in explaining sex differences in lifespan, but 41indicate that, at least in mammals, this is better explained by "toxic Y" rather than UXh 42 effects. 43 44 45 46 47 48 MAIN 52Sexual dimorphism in lifespan is widespread across the tree of life, including among tetrapods 53[1]. Which sex lives longer varies considerably in both direction and magnitude. For example, 54 females live three times longer than males in the brown antechinus, a small marsupial, while 55 males are twice as likely as females to survive from one year to the next in Arabian babblers, 56 a passerine bird [2, 3]. In humans, the lifespan gap is estimated to be 4.8 years -female life 57 expectancy is 74.7 years while male life expectancy is 69.9 years [4]. Understanding the 58 dynamic nature of sex differences in lifespan across taxa remains an unsolved problem in 59 evolutionary biology. To date, empirical studies have focused on adaptive hypotheses 60 stemming from sex-specific differences in how natural selection operates on females and 61 males [1, 5-8]. Despite their prominent role in explaining sex differences in ageing, adaptive 62processes seem unable to explain the observation that the homogametic sex tends to live 63 longer than the heterogametic sex across a wide taxonomic range [1, 9]. 64 65There are at least two reasons why sex chromosomes should directly contribute to the 66 evolution of different female and male lifespans [9, 10]. First, the unguarded X hypothesis 67 (UXh) predicts increased mortality of the heterogametic sex due to the expression of 68 deleterious recessive mutations that accumulate in the non-recombining parts of the X (or Z) 69 chromosome [10]. Because these mutations are masked in the homogametic s...

show abstract

Section: Mainmentioning

confidence: 99%

Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

Sultanova

Downing

Carazo

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…We then set out to determine whether a marked Y-chromosome could be useful in identifying the rare progeny resulting from meiotic sex chromosome nondisjunction events in females (Figure 2A-B), as a clear means for identification of such individuals could be useful both for those that want to avoid them and those that wish to utilize them for addressing various research questions (e.g., Brown & Bachtrog 2017). To do this, we crossed males from the stronger-expressing of our two transgenic Y-chromosome lines, AByF, to a variety of Xchromosome balancer line virgins containing genetic elements such as inversions and rearrangements that are known to increase the probability of nondisjunction (Xiang & Hawley 2006;Gilliland et al 2014).…”

Section: Resultsmentioning

confidence: 99%

“…In short, here we describe the engineering of two Y-chromosome marked transgenic D. melanogaster lines using site-specific, CRISPR/Cas9-mediated insertion. This may be useful for generating, identifying, and tracking progeny arising from rare meiotic nondisjunction events in a more straightforward manner than typically used (Brown & Bachtrog 2017;Piergentili 2010;Hess & Meyer 1968). More broadly, however, we provide a proof of principle example of a CRISPR/Cas-based strategy for docking transgenes site-specifically on the Y-chromosome that should in principle be applicable to many other species.…”

Section: Resultsmentioning

confidence: 99%

“…Although the often-heterochromatic nature of a Y-chromosome may, as we observed here, reduce the number of targeted insertion sites that are amenable to modification and/or robust transgene expression, the ease with which distinct Y-chromosome targeting transgene cassettes can be generated should allow for testing of many possible insertion sites, greatly increasing the chances of successful transgene integration with desired expression. The ability to mark, and express transgenes directly from, the Ychromosome not only allows for facile identification of Y-chromosome bearing individuals at various life stages and enables researchers to probe the enigmatic function of the Y-chromosome (e.g., (Brown & Bachtrog 2017;Bernardini et al 2014), but could also help pave the way for engineering genetic insect vector and pest control strategies such as X-chromosome shredding (Hickey & Craig 1966;Hamilton 1967;Gould & Schliekelman 2004;Huang et al 2007;Galizi et al 2014;Champer et al 2016;Galizi et al 2016). This approach in particular depends on the destruction of X-bearing sperm to produce males that only give rise to male progeny (Huang et al 2007;Champer et al 2016), and requires the ability to meiotically express an X-chromosome targeting element from the Y-chromosome (Beaghton et al 2016;Galizi et al 2016).…”

Section: Resultsmentioning

confidence: 99%

“…Firstly, the ability to mark the Y-chromosome with an easily-scorable, specific marker may in itself be useful. For example, it would allow for the facile identification of rare Ybearing or Y-lacking individuals (e.g., XXY females and XO males arising from nondisjunction, Figure 2A; Bridges 1913;Bridges 1916), which can be of experimental use (e.g., Brown & Bachtrog 2017;Lemos et al 2010;Hearn et al 1991;Yang et al 2012). A marked Y-chromosome would also enable interspecific Y-chromosome introgression studies, which can shed light on Y-chromosome evolution and function (Araripe et al 2016;Sackton et al 2011;Bernardini et al 2017), and can also be useful for sexing embryos (Bernardini et al 2014;Condon et al 2007), although it would also mark XXY females and fail to identify XO males, which may be problematic for certain applications.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Site-specific transgenesis of theD. melanogasterY-chromosome using CRISPR/Cas9

Buchman

Akbari

2018

Preprint

View full text Add to dashboard Cite

Despite the importance of Y-chromosomes in evolution and sex determination, their heterochromatic, repeat-rich nature makes them difficult to sequence and genetically manipulate, and therefore they generally remain poorly understood. For example, the D. melanogaster Ychromosome, one of the best understood, is widely heterochromatic and composed mainly of highly repetitive sequences, with only a handful of expressed genes scattered throughout its length. Efforts to insert transgenes on this chromosome have thus far relied on either random insertion of transposons (sometimes harboring 'landing sites' for subsequent integrations) with limited success or on chromosomal translocations, thereby limiting the types of Y-chromosome related questions that could be explored. Here we describe a versatile approach to sitespecifically insert transgenes on the Y-chromosome in D. melanogaster via CRISPR/Cas9mediated HDR. We demonstrate the ability to insert, and detect expression from, fluorescently marked transgenic transgenes at two specific locations on the Y-chromosome, and we utilize these marked Y-chromosomes to detect and quantify rare chromosomal nondisjunction effects. Finally, we discuss how this Y-docking technique could be adapted to other insects to aid in the development of genetic control technologies for the management of insect disease vectors and pests.

show abstract

Evidence for feminized genetic males in a flea beetle using newly identified X‐linked markers

Rohlfing,

Grewoldt,

Cordellier

et al. 2024

Ecology and Evolution

View full text Add to dashboard Cite

The equilibrium of sex ratios in sexually reproducing species is often disrupted by various environmental and genetic factors, including endosymbionts like Wolbachia. In this study, we explore the highly female‐biased sex ratio observed in the flea beetle, Altica lythri, and its underlying mechanisms. Ancient hybridization events between Altica species have led to mitochondrial DNA introgression, resulting in distinct mitochondrial haplotypes that go along with different Wolbachia infections (HT1‐wLytA1, HT1*‐ uninfected, HT2‐wLytA2, and HT3‐wLytB). Notably, beetles with some haplotypes exclusively produce female offspring, suggesting potential Wolbachia‐induced phenomena such as feminization of genetic males. However, the observed female bias could also be a consequence of the ancient hybridization resulting in nuclear–cytoplasmic conflicts between introgressed mtDNA and nuclear genes. Through transcriptomic analysis and the program SEX‐DETector, we established markers for genotypic sex differentiation for A. lythri, enabling genetic sexing via qPCR. Our findings suggest that feminization of genetic males is contributing to the skewed sex ratios, highlighting the intricate dynamics of sex determination and reproductive strategies in this flea beetle. This study provides valuable insights into the dynamics of genetic conflicts, endosymbionts, and sex ratios, revealing the novel phenomenon of genetic male feminization in the flea beetle A. lythri.

show abstract

The Drosophila Y Chromosome Affects Heterochromatin Integrity Genome-Wide

Cited by 57 publications

References 76 publications

Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

Site-specific transgenesis of theD. melanogasterY-chromosome using CRISPR/Cas9

Evidence for feminized genetic males in a flea beetle using newly identified X‐linked markers

Contact Info

Product

Resources

About