Sciara as an experimental model for studies on the evolutionary relationships between the zygotic, maternal and environmental primary signals for sexual development

Sánchez, Lucas

doi:10.1007/s12041-010-0044-8

Cited by 10 publications

(5 citation statements)

References 32 publications

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“…A major prediction of systems with paternal genome elimination is maternal control over offspring sex ratio (Haig 1993;Varndell and Godfray 1996;Nagelkerke and Sabelis 1998;Sánchez 2010). We set up an experiment to test whether females exhibit facultative sex allocation by examining whether female age and rearing condition affect sex ratio.…”

Section: Sex Allocation In Liposcelis Sp Femalesmentioning

confidence: 99%

Paternal Genome Elimination in Liposcelis Booklice (Insecta: Psocodea)

et al. 2017

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How sex is determined in insects is diverse and dynamic, and includes male heterogamety, female heterogamety, and haplodiploidy. In many insect lineages, sex determination is either completely unknown or poorly studied. We studied sex determination in Psocodea-a species-rich order of insects that includes parasitic lice, barklice, and booklice. We focus on a recently discovered species of booklice (Psocodea: Troctomorpha), which are among the closest free-living relatives of parasitic lice. Using genetic, genomic, and immunohistochemical approaches, we show that this group exhibits paternal genome elimination (PGE), an unusual mode of sex determination that involves genomic imprinting. Controlled crosses, following a genetic marker over multiple generations, demonstrated that males only transmit to offspring genes they inherited from their mother. Immunofluorescence microscopy revealed densely packed chromocenters associated with H3K9me3-a conserved marker for heterochromatin-in males, but not in females, suggesting silencing of chromosomes in males. Genome assembly and comparison of read coverage in male and female libraries showed no evidence for differentiated sex chromosomes. We also found that females produce more sons early in life, consistent with facultative sex allocation. It is likely that PGE is widespread in Psocodea, including human lice. This order represents a promising model for studying this enigmatic mode of sex determination.

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Section: Sex Allocation In Liposcelis Sp Femalesmentioning

confidence: 99%

Paternal Genome Elimination in Liposcelis Booklice (Insecta: Psocodea)

et al. 2017

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“…However, the development of new molecular biology techniques, such as the analysis of transcriptomes, make it now possible to undertake the characterization of genes involved in controlling sex determination in these insects. To this respect, Sciara has been proposed as an experimental model for studies on the evolutionary relationships between the zygotic, maternal and environmental primary signals for sexual development, since in this dipteran, the zygotic signal is a consequence of the maternal signal, and this in turn can be a consequence of the environmental signal (a detailed justification can be found in Sánchez [2010]). …”

Section: Perspectivesmentioning

confidence: 99%

Sex-Determining Mechanisms in Insects Based on Imprinting and Elimination of Chromosomes

Sánchez¹

2013

Sex Dev

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As a rule, the sex of an individual is fixed at fertilization, and the chromosomal constitution of the zygote is a direct consequence of the chromosomal constitution of the gametes. However, there are cases in which the chromosomal differences determining sex are brought about by elimination or inactivation of chromosomes in the embryo. In Sciaridae insects, all zygotes start with the XXX constitution; the loss of either 1 or 2 X chromosomes determines whether the zygote becomes XX (female) or X0 (male). In Cecydomyiidae and Collembola insects, all zygotes start with the XXXX constitution. If the embryo does not eliminate any X chromosome, this remains XXXX and develops as female, whereas if 2 X chromosomes are eliminated, the embryo becomes XX0 and develops as a male. In the coccids (scale insects), the chromosomal differences between the sexes result from either the elimination or the heterochromatinization (inactivation) of half of the chromosomes giving rise to haploid males and diploid females. The chromosomes that are eliminated or inactivated are those inherited from the father. Therefore, in the formation of the sex-determining chromosomal signal in those insects, a marking (‘imprinting') process must occur in one of the parents, which determines that the chromosomes to be eliminated or inactivated are of paternal origin. In this article, the sex determination mechanism of these insects and the associated imprinting process are reviewed.

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“…Here, sex is determined by the genotype of the mother instead of that of the zygote: mothers are genetically predetermined to produce either only male offspring or only female offspring. Monogenic sex determination has evolved in three clades of flies (Diptera): blowflies (Chrysomyinae, 5, 6), gall midges (Ceccidomyiidae, 7–9) and fungus gnats (Sciaridae, 10–12). Little is known about control of sex determination in blowflies (13).…”

Section: Introductionmentioning

confidence: 99%

Recent evolution of a maternally-acting sex-determining supergene in a fly with single-sex broods

Baird

Urban

Mongue

et al. 2022

Preprint

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Sex determination is a key developmental process, yet it is remarkably variable across the tree of life. The dipteran family Sciaridae exhibits one of the most unusual sex determination systems in which mothers control offspring sex through selective elimination of paternal X chromosomes. Whereas in some members of the family females produce mixed-sex broods, others such as the dark-winged fungus gnat Bradysia coprophila are monogenic, with females producing single-sex broods. Female-producing females were previously found to be heterozygous for a large X-linked paracentric inversion (X'), which is maternally inherited and absent from male-producing females. Here we assembled and characterized the X' sequence. As close sequence homology between the X and X' made identification of the inversion challenging, we developed a k-mer-based approach to bin genomic reads before assembly. We confirmed that the inversion spans most of the X' chromosome (approximately 55Mb) and encodes around 3500 genes. Analysis of the divergence between the inversion and the homologous region of the X revealed that it originated very recently (<0.5 mya). Surprisingly, we found that the X' is more complex than previously thought and is likely to have undergone multiple rearrangements that have produced regions of varying ages, resembling a supergene composed of evolutionary strata. We found functional degradation of around 7.3% of genes within the region of recombination suppression, but no evidence of accumulation of repetitive elements. Our findings provide an indication that sex-linked inversions are driving turnover of the strange sex determination system in this family of flies.

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Sciara as an experimental model for studies on the evolutionary relationships between the zygotic, maternal and environmental primary signals for sexual development

Cited by 10 publications

References 32 publications

Paternal Genome Elimination in Liposcelis Booklice (Insecta: Psocodea)

Paternal Genome Elimination in Liposcelis Booklice (Insecta: Psocodea)

Sex-Determining Mechanisms in Insects Based on Imprinting and Elimination of Chromosomes

Recent evolution of a maternally-acting sex-determining supergene in a fly with single-sex broods

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