Weak male-determining genes and female heterogamety in Chironomus tentans

1984 ◽  
Vol 26 (6) ◽  
pp. 748-751
Author(s):  
Ray Feraday
Keyword(s):  
Sex Determination ◽  
Sex Chromosome ◽  
Chironomus Tentans ◽  
Female Development ◽  
Female Heterogamety ◽  
Dominant Female

Female heterogamety in the midge Chironomus tentans has been previously reported and attributed to a dominant female determiner. Published results are not consistent with the interpretation, and the female heterogamety, if any, can be better explained by a model involving a weakened male determiner. Suggestions are made for crosses between populations with different sex-determining mechanisms that would discriminate between models for the evolution of female heterogamety, and serve to determine whether indeed female development is the norm in the absence of any parental sex chromosomes.Key words: Chironomus, heterogamety, sex determination, sex chromosome.

Are there female heterogametic strains of Chironomus tentans Fabricius?

1984 ◽  
Vol 26 (6) ◽  
pp. 743-747 ◽  
Author(s):  
Jon Martin ◽  
B. T. O. Lee
Keyword(s):  
Sex Determination ◽  
Published Data ◽  
Chironomus Tentans ◽  
Adequate Explanation ◽  
Male And Female ◽  
Female Heterogamety ◽  
Male Heterogamety

Although male heterogamety is the generally accepted method of sex determination in Chironomus, female heterogamety has been reported for some strains of Chironomus tentans. Some new data, combined with a reassessment of the published data, indicate that the proposal of female heterogamety rests on inconclusive data, while male heterogamety provides an adequate explanation of sex determination in C. tentans. A cross which would unambiguously discriminate between male and female heterogamety in these strains is proposed, although it is considered unlikely that female heterogamety exists in this species.Key words: sex determination, female heterogamety, Chironomus.

scholarly journals INTERACTIONS OF DIFFERENTIATED PRIMARY SEX FACTORS IN CHIRONOMUS TENTANS

Genetics ◽  
1972 ◽  
Vol 70 (3) ◽  
pp. 491-493
Author(s):  
Peter E Thompson ◽  
Jean S Bowen
Keyword(s):  
Sex Determination ◽  
Chromosome 1 ◽  
Dominant Male ◽  
Chironomus Tentans ◽  
Sex Factors ◽  
Dominant Female ◽  
Different Populations ◽  
The Right ◽  
Determining Factor ◽  
Geographically Isolated

ABSTRACT Different populations of Chironomus tentans, possibly representing geographically isolated races, have two differentiated genic mechanisms of sex determination involving either a dominant male-determining factor in the left arm of chromosome 1 or a dominant female-determining factor at the right tip of chromosome 1. In crosses between these populations, the male-determining factor is epistatic to the female-determining factor. No evidence of intersexuality has been found in such crosses.

MALE AND FEMALE HETEROGAMETY IN POPULATIONS OF CHIRONOMUS TENTANS (DIPTERA: CHIRONOMIDAE)

1971 ◽  
Vol 103 (3) ◽  
pp. 369-372 ◽  
Author(s):  
Peter E. Thompson
Keyword(s):  
Sex Determination ◽  
Chromosome 1 ◽  
Chironomus Tentans ◽  
Male And Female ◽  
Dominance Relations ◽  
Female Heterogamety ◽  
The Right

AbstractPopulations of Chironomus tentans from Iowa and Wisconsin show consistent polymorphisms for inversion sequences of chromosome 1 which are associated with sex. Male larvae from Iowa populations are invariably heterozygous for a sequence of the left arm which is never present in females. In a Wisconsin population, however, females are consistently heterozygous for a dominant sex factor, female determiner (Fd), linked to but not inseparable from an inversion sequence of the right arm. Two primary loci for sex determination appear to have evolved different dominance relations in these races.

scholarly journals Triploid plover female provides support for a role of the W chromosome in avian sex determination

2012 ◽  
Vol 8 (5) ◽  
pp. 787-789 ◽  
Author(s):  
Clemens Küpper ◽  
Jakob Augustin ◽  
Scott Edwards ◽  
Tamás Székely ◽  
András Kosztolányi ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosome ◽  
W Chromosome ◽  
Female Development ◽  
Linked Gene ◽  
Charadrius Alexandrinus ◽  
Male Development ◽  
Polymorphic Microsatellite ◽  
Kentish Plover

Two models, Z Dosage and Dominant W , have been proposed to explain sex determination in birds, in which males are characterized by the presence of two Z chromosomes, and females are hemizygous with a Z and a W chromosome. According to the Z Dosage model, high dosage of a Z-linked gene triggers male development, whereas the Dominant W model postulates that a still unknown W-linked gene triggers female development. Using 33 polymorphic microsatellite markers, we describe a female triploid Kentish plover Charadrius alexandrinus identified by characteristic triallelic genotypes at 14 autosomal markers that produced viable diploid offspring. Chromatogram analysis showed that the sex chromosome composition of this female was ZZW. Together with two previously described ZZW female birds, our results suggest a prominent role for a female determining gene on the W chromosome. These results imply that avian sex determination is more dynamic and complex than currently envisioned.

scholarly journals Transition from environmental to partial genetic sex determination in Daphnia through the evolution of a female-determining incipient W-chromosome

2016 ◽  
Author(s):  
Céline M.O. Reisser ◽  
Dominique Fasel ◽  
Evelin Hürlimann ◽  
Marinela Dukič ◽  
Cathy Haag-Liautard ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Sex Differentiation ◽  
Genomic Region ◽  
Additional Restriction ◽  
W Chromosome ◽  
Recombination Suppression ◽  
Evolutionary Transitions ◽  
Dominant Female

AbstractSex chromosomes can evolve during the evolution of genetic sex determination (GSD) from environmental sex determination (ESD). Despite theoretical attention, early mechanisms involved in the transition from ESD to GSD have yet to be studied in nature. No mixed ESD-GSD animal species have been reported, except for some species of Daphnia, small freshwater crustaceans in which sex is usually determined solely by the environment, but in which a dominant female sex-determining locus is present in some populations. This locus follows Mendelian single-locus inheritance, but has otherwise not been characterized genetically. We now show that the sex-determining genomic region maps to the same low-recombining peri-centromeric region of linkage group 3 (LG3) in three highly divergent populations of D. magna, and spans 3.6 Mb. Despite low levels of recombination, the associated region contains signs of historical recombination, suggesting a role for selection acting on several genes thereby maintaining linkage disequilibrium among the 36 associated SNPs. The region carries numerous genes involved in sex differentiation in other taxa, including transformer2 and sox9. Taken together, the region determining the NMP phenotype shows characteristics of a sex-related supergene, suggesting that LG3 is potentially an incipient W chromosome despite the lack of significant additional restriction of recombination between Z and W. The occurrence of the female-determining locus in a pre-existing low recombining region illustrates one possible form of recombination suppression in sex chromosomes. D. magna is a promising model for studying the evolutionary transitions from ESD to GSD and early sex chromosome evolution.

scholarly journals Evolution of sex determination and heterogamety changes in section Otites of the genus Silene

2018 ◽  
Author(s):  
Veronika Balounova, ◽  
Roman Gogela ◽  
Radim Cegan ◽  
Patrik Cangren ◽  
Jitka Zluvova ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Sex Determination ◽  
Sex Chromosome ◽  
The Other ◽  
Close Relative ◽  
Sequence Analyses ◽  
Female Heterogamety ◽  
Genus Silene ◽  
Plant Sex ◽  
Male Heterogamety

AbstractSwitches in heterogamety occasionally occur both in animals and plants, although plant sex determination systems are mostly more recently evolved than those of animals, and have had less time for switches to occur. However, our previous research revealed a switch in heterogamety in section Otites of the plant genus Silene.Here we analyse in detail the evolution of genetic sex determination in section Otites, which is estimated to have evolved about 0.55 MYA. Our study confirms female heterogamety in S. otites and newly reveals female heterogamety in S. borysthenica. Sequence analyses and genetic mapping show that the sex-linked regions of these two species are the same, but the region in S. colpophylla, a close relative with male heterogamety, is different. The sex chromosome pairs of S. colpophylla and S. otites each correspond to an autosome of the other species, and both differ from the XY pair in S. latifolia, in a different section of the genus. Our phylogenetic analysis suggests a possible change from female to male heterogamety within Silene section Otites, making these species suitable for detailed studies of the events involved.

Monotreme sex chromosomes - implications for the evolution of amniote sex chromosomes

2009 ◽  
Vol 21 (8) ◽  
pp. 943 ◽  
Author(s):  
Paul D. Waters ◽  
Jennifer A. Marshall Graves
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Female Development ◽  
Comparative Gene Mapping ◽  
Y Chromosomes ◽  
Daunting Task ◽  
Platypus Genome ◽  
Genetic Events

In vertebrates, a highly conserved pathway of genetic events controls male and female development, to the extent that many genes involved in human sex determination are also involved in fish sex determination. Surprisingly, the master switch to this pathway, which intuitively could be considered the most critical step, is inconsistent between vertebrate taxa. Interspersed in the vertebrate tree there are species that determine sex by environmental cues such as the temperature at which eggs are incubated, and then there are genetic sex-determination systems, with male heterogametic species (XY systems) and female heterogametic species (ZW systems), some of which have heteromorphic, and others homomorphic, sex chromosomes. This plasticity of sex-determining switches in vertebrates has made tracking the events of sex chromosome evolution in amniotes a daunting task, but comparative gene mapping is beginning to reveal some striking similarities across even distant taxa. In particular, the recent completion of the platypus genome sequence has completely changed our understanding of when the therian mammal X and Y chromosomes first arose (they are up to 150 million years younger than previously thought) and has also revealed the unexpected insight that sex determination of the amniote ancestor might have been controlled by a bird-like ZW system.

scholarly journals Preface

2021 ◽  
Vol 376 (1832) ◽  
pp. 20200088
Author(s):  
Lukáš Kratochvíl ◽  
Matthias Stöck
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Sex Chromosome Evolution ◽  
Evolution Of Sex ◽  
Linkage Groups ◽  
Theme Issue ◽  
Female Heterogamety

This preface introduces the two parts of a theme issue on vertebrate sex chromosome evolution (title below). We invited and edited 22 articles concerning the following main topics (Part 1): sex determination without sex chromosomes and/or governed by epigenetics; origin of sex-determining genes; reasons for differentiation of sex chromosomes and differences in their rates of differentiation as well as (Part 2): co-option of the same linkage groups into sex chromosomes; is differentiation of sex chromosomes a unidirectional pathway?; consequences of differentiated sex chromosomes; differences in differentiation of sex chromosomes under male versus female heterogamety; evolution of sex chromosomes under hybridization and polyploidy. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.

scholarly journals Genomic Data Reveal Conserved Female Heterogamety in Giant Salamanders with Gigantic Nuclear Genomes

2019 ◽  
Vol 9 (10) ◽  
pp. 3467-3476 ◽  
Author(s):  
Paul M. Hime ◽  
Jeffrey T. Briggler ◽  
Joshua S. Reece ◽  
David W. Weisrock
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Model Organisms ◽  
Reduced Representation ◽  
Non Invasive ◽  
Female Heterogamety ◽  
Genome Wide ◽  
Great Utility ◽  
Genomic Regions

Systems of genetic sex determination and the homology of sex chromosomes in different taxa vary greatly across vertebrates. Much progress remains to be made in understanding systems of genetic sex determination in non-model organisms, especially those with homomorphic sex chromosomes and/or large genomes. We used reduced representation genome sequencing to investigate genetic sex determination systems in the salamander family Cryptobranchidae (genera Cryptobranchus and Andrias), which typifies both of these inherent difficulties. We tested hypotheses of male- or female-heterogamety by sequencing hundreds of thousands of anonymous genomic regions in a panel of known-sex cryptobranchids and characterized patterns of presence/absence, inferred zygosity, and depth of coverage to identify sex-linked regions of these 56 gigabase genomes. Our results strongly support the hypothesis that all cryptobranchid species possess homologous systems of female heterogamety, despite maintenance of homomorphic sex chromosomes over nearly 60 million years. Additionally, we report a robust, non-invasive genetic assay for sex diagnosis in Cryptobranchus and Andrias which may have great utility for conservation efforts with these endangered salamanders. Co-amplification of these W-linked markers in both cryptobranchid genera provides evidence for long-term sex chromosome stasis in one of the most divergent salamander lineages. These findings inform hypotheses about the ancestral mode of sex determination in salamanders, but suggest that comparative data from other salamander families are needed. Our results further demonstrate that massive genomes are not necessarily a barrier to effective genome-wide sequencing and that the resulting data can be highly informative about sex determination systems in taxa with homomorphic sex chromosomes.

scholarly journals wnt4a promotes female development and reproductive duct elongation in zebrafish

2018 ◽  
Author(s):  
Michelle E. Kossack ◽  
Samantha K. High ◽  
Rachel E. Hopton ◽  
Yi-lin Yan ◽  
John H. Postlethwait ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosome ◽  
Ovary Development ◽  
Last Common Ancestor ◽  
Loss Of Function ◽  
Female Development ◽  
Male And Female ◽  
Female Sex ◽  
Somatic Gonad ◽  
Duct Development

ABSTRACTIn laboratory strains of zebrafish, sex determination occurs in the absence of a typical sex chromosome and it is not known what regulates the proportion of animals that develop as male or female. Many sex determination and differentiation genes that act downstream of a sex chromosome are well conserved among vertebrates, but studies that test their contribution to this process have mostly been limited to mammalian models. In mammals, WNT4 is a signaling ligand that is essential for ovary and Müllerian duct development, where it function, in part, to antagonize the male-promoting FGF9 signal. Wnt4 is highly conserved in non-mammalian vertebrates, but it is not known if Wnt4 plays a role in sex determination and/or the differentiation of sex organs outside of mammals. This is an especially interesting question in teleost, such as zebrafish, because they lack an Fgf9 ortholog. Here we show that wnt4a is the ortholog of mammalian Wnt4, and that wnt4b was present in the last common ancestor of humans and zebrafish, but was lost in mammals. We found that wnt4a is expressed in the somatic cells of juvenile gonads during the time sex determination likely occurs. We show that wnt4a loss-of-function mutants develop predominantly as males and conclude that wnt4a activity promotes female sex determination in zebrafish. Additionally, both male and female wnt4a mutants are sterile because their reproductive ducts do not connect to the vent, where wnt4a is normally expressed. Yet when dissected from homozygous wnt4a mutant gonads, both sperm and eggs can produce fertile offspring. Together these results strongly argue that Wnt4a is a conserved regulator of female sex determination and reproductive duct development in non-mammalian vertebrates.SUMMARYWnt4 is a key regulator of ovary development in mammals, but it is not known if it plays a similar role in other vertebrates. Here we show that zebrafish wnt4a is the ortholog of mammalian Wnt4. We show that wnt4a is expressed in zebrafish somatic gonad cells during the time sex determination likely occurs. Through analysis of wnt4a mutants, we show that Wnt4a promotes female sex determination and the development of the male and female reproductive. We conclude that Wnt4/Wnt4a is likely a conserved regulator of ovarian and reproductive duct development in all vertebrates

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