Triploid Colubrid Snake Provides Insight into the Mechanism of Sex Determination in Advanced Snakes

Rovatsos, Michail; Augstenová, Barbora; Altmanová, Marie; Sloboda, Michal; Kodym, Petr; Kratochvíl, Lukáš

doi:10.1159/000490124

Cited by 17 publications

(20 citation statements)

References 27 publications

(26 reference statements)

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“…In support of this hypothesis, both studied lineages with female heterogamety likely relying on the dosage-dependent mechanism, i.e. birds and caenophidian snakes 57,58 , have a lack of global dosage balance 10,15 . At first sight, two model organisms, the fruit fly Drosophila melanogaster and the nematode worm Caenorhabditis elegans , represent a contradictory case, since it is textbook knowledge that their sex determination primarily relies on the number of copies of the X chromosome (in correlation to autosomes ratio), but at the same time they have global dosage compensation 59,60 .…”

Section: Discussionmentioning

confidence: 78%

Do male and female heterogamety really differ in expression regulation? Lack of global dosage balance in pygopodid geckos

Rovatsos

Gamble

Nielsen

et al. 2020

Preprint

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19Differentiation of sex chromosomes is thought to have evolved with cessation of 20 recombination and subsequent loss of genes from the degenerated partner (Y and W) of sex 21 chromosomes, which in turn leads to imbalance of gene dosage between sexes. Based on 22 work with traditional model species, theory suggests that unequal gene copy numbers lead to 23 the evolution of mechanisms to counter this imbalance. Dosage compensation, or at least 24 achieving dosage balance in expression of sex-linked genes between sexes, has largely been 25 documented in lineages with male heterogamety (XX/XY sex determination), while ZZ/ZW 26 systems are assumed to be usually associated with the lack of chromosome-wide gene dose 27 regulatory mechanisms. Here we document that although the pygopodid geckos evolved male 28 heterogamety with a degenerated Y chromosome 32-72 million years ago, one species in 29 particular, Burton's legless lizard (Lialis burtonis), does not possess dosage balance in the 30 expression of genes in its X-specific region. We summarize studies on gene dose regulatory 31 mechanisms in animals and conclude that there is in them no significant dichotomy between 32 male and female heterogamety. We speculate that gene dose regulatory mechanisms are likely 33 to be related to the general mechanisms of sex determination instead of type of heterogamety. 34Differentiated sex chromosomes evolved independently in numerous animal and plant 36 lineages 1 . The differentiation is connected with cessation of recombination and subsequent 37 loss of functional genes from the Y or W sex chromosomes which leads to gene dose 38 differences between sexes. Selection will favour the evolution of mechanisms that regulate 39 these differences at the cellular level, as alterations in gene copy number generally alters gene 40 expression, ultimately impacting cell physiology and organismal fitness 2-5 . Different taxa 41 have evolved distinct strategies to regulate the unequal gene copy numbers and the associated 42 gene dosage imbalances between the sexes related to differentiated sex chromosomes 6 . The 43 most well-known mechanism is dosage compensation, which restores the expression of X or 44 Z-specific genes in the heterogametic sex to the ancestral expression levels 7-9 . Dosage 45 compensation usually leads to dosage balance, i.e. equal expression levels of the X or Z-46 specific genes between the sexes, however some animal lineages can reach dosage balance in 47 the expression between sexes without keeping the ancestral expression level. Other animal 48 lineages do not compensate and balance expression in the majority of the sex-linked genes at 49 either the level of transcription or translation 10,11 . Dosage compensation or at least dosage 50 balance between sexes was documented largely in lineages with male heterogamety (XX/XY 51 sex determination) such as in several insect lineages, nematode worms, the green anole and 52 eutherian mammals, with sticklebacks, basilisks and platypus being exceptions 6,12,13 . On the 53 ...

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Section: Discussionmentioning

confidence: 78%

Do male and female heterogamety really differ in expression regulation? Lack of global dosage balance in pygopodid geckos

Rovatsos

Gamble

Nielsen

et al. 2020

Preprint

Self Cite

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“…Details about the origin of individuals from 9 species are described in previous studies ( Paroedura oviceps, P. stumpffi : Koubová et al [2014] Rovatsos et al [2018]). Blood samples of the other 5 species were obtained from animals from pet trade or private breeders.…”

Section: Animals and Chromosome Preparationsmentioning

confidence: 99%

“…The information on sex determination systems in other species was taken from Olmo et al [1986], Martinez et al [2008], Koubová et al [2014], Matsubara et al [2014], Altmanová et al [2016], Rovatsos et al [2015Rovatsos et al [ , 2016Rovatsos et al [ , 2018, and M. Altmanová (unpublished data in Anolis marmoratus ).…”

Section: Animals and Chromosome Preparationsmentioning

confidence: 99%

5-Methylcytosine-Rich Heterochromatin in Reptiles

Schmid

Steinlein

Reiter

et al. 2019

Cytogenet Genome Res

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An experimental approach using monoclonal anti-5-methylcytosine antibodies and indirect immunofluorescence was elaborated for detecting 5-methylcytosine-rich chromosome regions in reptilian chromosomes. This technique was applied to conventionally prepared mitotic metaphases of 2 turtle species and 12 squamate species from 8 families. The hypermethylation patterns were compared with C-banding patterns obtained by conventional banding techniques. The hypermethylated DNA sequences are species-specific and are located in constitutive heterochromatin. They are highly reproducible and often found in centromeric, pericentromeric, and interstitial positions of the chromosomes. Heterochromatic regions in differentiated sex chromosomes are particularly hypermethylated.

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“…Controlled mating of normal males to sex-reversed females produces a viable and fertile offspring whose phenotypic sex is determined solely by temperature (temperature-dependent sex determination). The W sex chromosome is eliminated from this lineage in the first generation which indicates its specific role in genetic sex [30].…”

Section: Sex In Reptiles: Determination Of Sex Under the Influence Ofmentioning

confidence: 99%

“…On the 6.5th day (30th stage), the first sex determining genes are activated. In the modern scheme of the genetic control of sex determination in birds (practically within the dose scheme), an epigenetic mechanism for switching off the single allele of avian key sex determining dmrt1 gene in females through hypermethylation and using noncoding MHM RNA came into sharp focus (Figure 8) [30][31][32][33][34]. Synthetic aromatase inhibitors (an enzyme catalyzing the synthesis of estrogens) can induce steady female → male sex inversion.…”

Section: The Continuum Of Sex Determination Distribution Mechanisms mentioning

confidence: 99%

Comparison of Sex Determination in Vertebrates (Nonmammals)

Smirnov¹,

Trukhina²

2020

Gene Expression and Phenotypic Traits

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The chapter is devoted to the consideration of sex determination in vertebrate groups of nonmammalians: fish, amphibians, reptiles, and birds. Attention is drawn to the fact that all these groups of animals, unlike mammals, are implemented hormonal control options for primary sex determination, and there is a possibility of sex reversion. Determination of gonadal development in vertebrates like testis or ovary was initially controlled mainly by sex hormones (fish and amphibians). Later, various sex determining genes were involved in this process. The system was quite plastic and was able to respond to changes in external conditions (reptiles). The appearance of heteromorphic sex chromosomes (birds) has led to the emergence of some specific W chromosomal signal, which provides estrogen control of the development of a heterogametic sex. In mammals, the control of the primary determination of sex (the appearance of the gonad) becomes purely genetic, and the role of sex hormones is reduced to the differentiation of testis or ovaries.

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Triploid Colubrid Snake Provides Insight into the Mechanism of Sex Determination in Advanced Snakes

Cited by 17 publications

References 27 publications

Do male and female heterogamety really differ in expression regulation? Lack of global dosage balance in pygopodid geckos

Do male and female heterogamety really differ in expression regulation? Lack of global dosage balance in pygopodid geckos

5-Methylcytosine-Rich Heterochromatin in Reptiles

Comparison of Sex Determination in Vertebrates (Nonmammals)

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