scholarly journals Sex Determining Mechanisms in Bivalves

2017 ◽  
Author(s):  
Sophie Breton ◽  
Charlotte Capt ◽  
Davide Guerra ◽  
Donald Stewart
Keyword(s):  
Final Section ◽  
Genetic Factors ◽  
Current Knowledge ◽  
Mitochondrial Genes ◽  
Uniparental Inheritance ◽  
Developmental Pathway ◽  
Doubly Uniparental Inheritance ◽  
Sexual Systems ◽  
Determination System ◽  
Sex Determination System

In this review, we provide an overview of the current knowledge on the different sexual systems and sex determining mechanisms in bivalves, with a focus on the various epigenetic and genetic factors that may be involved. The final section of the review provides recent discoveries on sex-specific mitochondrial genes in bivalves possessing the unconventional system of doubly uniparental inheritance of mitochondria (which is found in several members of the orders Mytiloida, Unionoida, Veneroida and Nuculanoida). The genes involved in this developmental pathway could represent the first sex determination system in animals in which mitochondrially-encoded genes are directly involved.

scholarly journals Presence of male mitochondria in somatic tissues and their functional importance at the whole animal level in the marine bivalve Arctica islandica

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Cyril Dégletagne ◽  
Doris Abele ◽  
Gernot Glöckner ◽  
Benjamin Alric ◽  
Heike Gruber ◽  
...  
Keyword(s):  
Mitochondrial Genes ◽  
Marine Bivalve ◽  
Uniparental Inheritance ◽  
Natural Occurrence ◽  
Doubly Uniparental Inheritance ◽  
Arctica Islandica ◽  
Sharp Drop ◽  
Respiratory Capacity ◽  
Icelandic Population ◽  
Somatic Tissues

AbstractMetazoans normally possess a single lineage of mitochondria inherited from the mother (♀-type mitochondria) while paternal mitochondria are absent or eliminated in fertilized eggs. In doubly uniparental inheritance (DUI), which is specific to the bivalve clade including the ocean quahog, Arctica islandica, ♂-type mitochondria are retained in male gonads and, in a few species, small proportions of ♂-type mitochondria co-exist with ♀-type in somatic tissues. To the best of our knowledge, we report, for the first time in metazoan, the natural occurrence of male and female individuals with exclusively ♂-type mitochondria in somatic tissues of the bivalve A. islandica. Mitochondrial genomes differ by ~5.5% at DNA sequence level. Exclusive presence of ♂-type mitochondria affects mitochondrial complexes partially encoded by mitochondrial genes and leads to a sharp drop in respiratory capacity. Through a combination of whole mitochondrial genome sequencing and molecular assays (gene presence and expression), we demonstrate that 1) 11% of individuals of an Icelandic population appear homoplasmic for ♂-type mitochondria in somatic tissues, 2) ♂-type mitochondrial genes are transcribed and 3) individuals with ♂-type mitochondria in somatic cells lose 30% of their wild-type respiratory capacity. This mitochondrial pattern in A. islandica is a special case of DUI, highlighted in individuals from both sexes with functional consequences at cellular and conceivably whole animal level.

scholarly journals Variability of mitochondrial ORFans hints at possible differences in the system of doubly uniparental inheritance of mitochondria among families of freshwater mussels (Bivalvia: Unionida)

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Davide Guerra ◽  
Manuel Lopes-Lima ◽  
Elsa Froufe ◽  
Han Ming Gan ◽  
Paz Ondina ◽  
...  
Keyword(s):  
Freshwater Mussels ◽  
Complete Mitochondrial Genome ◽  
Physiological Role ◽  
Freshwater Mussel ◽  
Single Species ◽  
Open Reading Frames ◽  
Uniparental Inheritance ◽  
Doubly Uniparental Inheritance ◽  
Sexual Systems ◽  
Mitogenome Sequence

Abstract Background Supernumerary ORFan genes (i.e., open reading frames without obvious homology to other genes) are present in the mitochondrial genomes of gonochoric freshwater mussels (Bivalvia: Unionida) showing doubly uniparental inheritance (DUI) of mitochondria. DUI is a system in which distinct female-transmitted and male-transmitted mitotypes coexist in a single species. In families Unionidae and Margaritiferidae, the transition from dioecy to hermaphroditism and the loss of DUI appear to be linked, and this event seems to affect the integrity of the ORFan genes. These observations led to the hypothesis that the ORFans have a role in DUI and/or sex determination. Complete mitochondrial genome sequences are however scarce for most families of freshwater mussels, therefore hindering a clear localization of DUI in the various lineages and a comprehensive understanding of the influence of the ORFans on DUI and sexual systems. Therefore, we sequenced and characterized eleven new mitogenomes from poorly sampled freshwater mussel families to gather information on the evolution and variability of the ORFan genes and their protein products. Results We obtained ten complete plus one almost complete mitogenome sequence from ten representative species (gonochoric and hermaphroditic) of families Margaritiferidae, Hyriidae, Mulleriidae, and Iridinidae. ORFan genes are present only in DUI species from Margaritiferidae and Hyriidae, while non-DUI species from Hyriidae, Iridinidae, and Mulleriidae lack them completely, independently of their sexual system. Comparisons among the proteins translated from the newly characterized ORFans and already known ones provide evidence of conserved structures, as well as family-specific features. Conclusions The ORFan proteins show a comparable organization of secondary structures among different families of freshwater mussels, which supports a conserved physiological role, but also have distinctive family-specific features. Given this latter observation and the fact that the ORFans can be either highly mutated or completely absent in species that secondarily lost DUI depending on their respective family, we hypothesize that some aspects of the connection among ORFans, sexual systems, and DUI may differ in the various lineages of unionids.

scholarly journals Environmental stress maintains trioecy in nematode worms

2019 ◽  
Author(s):  
Ashlyn G. Anderson ◽  
Louis T. Bubrig ◽  
Janna L. Fierst
Keyword(s):  
Life History ◽  
Sex Determination ◽  
Environmental Conditions ◽  
Natural Habitat ◽  
Population Level ◽  
Evolutionary Transitions ◽  
Sexual Systems ◽  
Determination System ◽  
Stable Maintenance ◽  
Sex Determination System

AbstractSex is determined by chromosomes in mammals but it can be influenced by the environment in many worms, crustaceans and vertebrates. Despite this, there is little understanding of the relationship between ecology and the evolution of sexual systems. The nematode Auanema freiburgensis has a unique sex determination system in which individuals carrying one X chromosome develop into males while XX individuals develop into females in stress-free environments and self-fertile hermaphrodites in stressful environments. Theory predicts that trioecious populations with coexisting males, females and hermaphrodites should be unstable intermediates in evolutionary transitions between mating systems. In this article we study a mathematical model of reproductive evolution based on the unique life history and sex determination of A. freiburgensis. We develop the model in two scenarios, one where the relative production of hermaphrodites and females is entirely dependent on the environment and one based on empirical measurements of a population that displays incomplete, ‘leaky’ environmental dependence. In the first scenario environmental conditions can push the population along an evolutionary continuum and result in the stable maintenance of multiple reproductive systems. The second ‘leaky’ scenario results in the maintenance of three sexes for all environmental conditions. Theoretical investigations of reproductive system transitions have focused on the evolutionary costs and benefits of sex. Here, we show that the flexible sex determination system of A. freiburgensis may contribute to population-level resilience in the microscopic nematode’s patchy, ephemeral natural habitat. Our results demonstrate that life history, ecology and environment may play defining roles in the evolution of sexual systems.

scholarly journals Atypical mitochondrial inheritance patterns in eukaryotes

Genome ◽  
2015 ◽  
Vol 58 (10) ◽  
pp. 423-431 ◽  
Author(s):  
Sophie Breton ◽  
Donald T. Stewart
Keyword(s):  
Sex Determination ◽  
Molecular Mechanisms ◽  
Maternal Inheritance ◽  
Uniparental Inheritance ◽  
Mitochondrial Inheritance ◽  
Doubly Uniparental Inheritance ◽  
Inheritance Patterns ◽  
Sexual Systems ◽  
Evolutionary Forces ◽  
Mtdna Inheritance

Mitochondrial DNA (mtDNA) is predominantly maternally inherited in eukaryotes. Diverse molecular mechanisms underlying the phenomenon of strict maternal inheritance (SMI) of mtDNA have been described, but the evolutionary forces responsible for its predominance in eukaryotes remain to be elucidated. Exceptions to SMI have been reported in diverse eukaryotic taxa, leading to the prediction that several distinct molecular mechanisms controlling mtDNA transmission are present among the eukaryotes. We propose that these mechanisms will be better understood by studying the deviations from the predominating pattern of SMI. This minireview summarizes studies on eukaryote species with unusual or rare mitochondrial inheritance patterns, i.e., other than the predominant SMI pattern, such as maternal inheritance of stable heteroplasmy, paternal leakage of mtDNA, biparental and strictly paternal inheritance, and doubly uniparental inheritance of mtDNA. The potential genes and mechanisms involved in controlling mitochondrial inheritance in these organisms are discussed. The linkage between mitochondrial inheritance and sex determination is also discussed, given that the atypical systems of mtDNA inheritance examined in this minireview are frequently found in organisms with uncommon sexual systems such as gynodioecy, monoecy, or andromonoecy. The potential of deviations from SMI for facilitating a better understanding of a number of fundamental questions in biology, such as the evolution of mtDNA inheritance, the coevolution of nuclear and mitochondrial genomes, and, perhaps, the role of mitochondria in sex determination, is considerable.

scholarly journals Differential Segregation Patterns of Sperm Mitochondria in Embryos of the Blue Mussel (Mytilus edulis)

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 883-894
Author(s):  
Liqin Cao ◽  
Ellen Kenchington ◽  
Eleftherios Zouros
Keyword(s):  
Mitochondrial Dna ◽  
Mytilus Edulis ◽  
Blue Mussel ◽  
Uniparental Inheritance ◽  
Male Gonad ◽  
Doubly Uniparental Inheritance ◽  
Organelle Genomes ◽  
Somatic Tissues ◽  
Tight Linkage ◽  
Mitotracker Green

Abstract In Mytilus, females carry predominantly maternal mitochondrial DNA (mtDNA) but males carry maternal mtDNA in their somatic tissues and paternal mtDNA in their gonads. This phenomenon, known as doubly uniparental inheritance (DUI) of mtDNA, presents a major departure from the uniparental transmission of organelle genomes. Eggs of Mytilus edulis from females that produce exclusively daughters and from females that produce mostly sons were fertilized with sperm stained with MitoTracker Green FM, allowing observation of sperm mitochondria in the embryo by epifluorescent and confocal microscopy. In embryos from females that produce only daughters, sperm mitochondria are randomly dispersed among blastomeres. In embryos from females that produce mostly sons, sperm mitochondria tend to aggregate and end up in one blastomere in the two- and four-cell stages. We postulate that the aggregate eventually ends up in the first germ cells, thus accounting for the presence of paternal mtDNA in the male gonad. This is the first evidence for different behaviors of sperm mitochondria in developing embryos that may explain the tight linkage between gender and inheritance of paternal mitochondrial DNA in species with DUI.

A proposed method for analyzing molecular signatures to detect hermaphroditism in freshwater mussels: a case study using the Eastern Floater (Pyganodon cataracta)

2021 ◽  
Author(s):  
Donald T. Stewart ◽  
Chloe M. Stephenson ◽  
Ljiljana M. Stanton ◽  
Emily E. Chase ◽  
Brent M. Robicheau ◽  
...  
Keyword(s):  
Freshwater Mussels ◽  
Uniparental Inheritance ◽  
Molecular Signatures ◽  
Doubly Uniparental Inheritance ◽  
Hydrophobic Properties ◽  
Mt Dna ◽  
Reading Frame ◽  
Mt Genome ◽  
Primary Nucleotide Sequence

Many freshwater mussels (Order Unionida) have an unusual system of doubly uniparental inheritance (DUI) of mitochondrial (mt) DNA. In species with DUI, males possess a female-transmitted (F-type) mt genome and a male-transmitted (M-type) mt genome. These genomes contain non-canonical open reading frame (orf) genes referred to as f-orf and m-orf, present in F and M mt genomes, respectively. These genes have been implicated in sexual development in Unionida. When gonochoric species become hermaphroditic, which has happened several times in Unionida, they lose their M-type mt genome, and f-orf genes evolve dramatically. Resulting F-ORF proteins are highly divergent in terms of primary nucleotide sequence, inferred amino acids, and hydrophobic properties; these genes (and proteins) are referred to as hermaphroditic orfs or h-orfs (and H-ORFs). We investigated patterns of hydrophobicity divergence for H-ORF proteins in hermaphrodites versus F-ORF proteins in closely related gonochoric species against cytochrome c oxidase subunit 1 (cox1) divergences. This approach was used to assess whether cryptic hermaphrodites can be detected. Although we did not detect evidence for the recent transition of any populations of Eastern Floaters, Pyganodon cataracta (Say, 1817) to hermaphroditism, our analyses demonstrate that molecular signatures in mtDNA can be used to detect hermaphroditism in freshwater mussels.

SEX AND SUPERNUMERARY CHROMOSOMES IN THE DIOECIOUS GRASS SOHNSIA FILIFOLIA

1972 ◽  
Vol 14 (1) ◽  
pp. 175-180 ◽  
Author(s):  
D. N. Singh
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Supernumerary Chromosome ◽  
The Other ◽  
Male Plant ◽  
Diploid Male ◽  
Male And Female ◽  
Supernumerary Chromosomes ◽  
Determination System ◽  
Sex Determination System

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

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