Evidence for a Genomic Imprinting Sex Determination Mechanism in Nasonia vitripennis (Hymenoptera; Chalcidoidea)

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 233-242 ◽  
Author(s):  
Stephen L Dobson ◽  
Mark A Tanouye
Keyword(s):  
Sex Determination ◽  
Genomic Imprinting ◽  
Parasitic Wasp ◽  
Nasonia Vitripennis ◽  
Crossing Experiments ◽  
Proposed Model ◽  
Early Embryos ◽  
Study Support ◽  
Determination Mechanism ◽  
Paternal Sex Ratio

AbstractFive different models have been proposed for the sex determination mechanism of Chalcidoidea (Hymenoptera). Except for the most recently proposed model (genomic imprinting sex determination; GISD), each of these models has required complicating additions to explain observed phenomena. This report provides the first experimental test of the GISD model while simultaneously examining the four previously proposed models of sex determination. This test utilizes the parasitic wasp Nasonia vitripennis, crossing polyploid females with males harboring the paternal sex ratio chromosome (PSR). The results of this study support the GISD model as the mechanism of sex determination in Chalcidoidea. Specifically, crosses demonstrate that sex determination is independent of embryonic heterozygosity, ploidy, and gametic syngamy but is directly correlated with the embryonic presence of correctly imprinted chromosomes of paternal origin. These crossing experiments also provide information about the poorly characterized mechanisms of PSR, a supernumerary chromosome that induces paternal autosome loss in early embryos. The results demonstrate that the poor transmission of PSR through females is not a result of the ploidy of the host but of an alternative sex-dependent process. Crossing data reveal that PSR consistently induces the loss of the entire paternal complement that it accompanies, regardless of whether this complement is haploid or diploid.

Cytogenetic analysis of the paternal sex ratio chromosome of Nasonia vitripennis

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 157-161 ◽  
Author(s):  
Kent M. Reed
Keyword(s):  
Sex Ratio ◽  
Silver Staining ◽  
Organizer Region ◽  
Parasitic Wasp ◽  
Nucleolus Organizer Region ◽  
B Chromosome ◽  
Nucleolus Organizer ◽  
Nasonia Vitripennis ◽  
C Banding ◽  
Paternal Sex Ratio

Paternal sex ratio (PSR) is a B chromosome found in the parasitic wasp Nasonia vitripennis. PSR has a unique etiology in that it destroys the paternal chromosomes of fertilized eggs, resulting in the production of all male families. This study examined structural aspects of PSR including size, C-banding, and silver staining. PSR was found to constitute approximately 5.7% of the genome of carrier males. C-banding confirmed the heterochromatic nature of PSR and the data suggest that PSR remains primarily condensed throughout the cell cycle. Examination of prometaphase spermatocytes revealed a secondary constriction on PSR. The constriction, however, did not stain positive for nucleolus organizer activity. During mitosis, PSR and the pericentromeric regions of the A chromosomes displayed a temporal pattern of silver staining, involving dense precipitation of silver prior to metaphase. This reaction is indicative of a protein complex specific to the heterochromatin of these regions. The implications of these findings to the origin of PSR are discussed.Key words: Nasonia vitripennis, paternal sex ratio, B chromosome, nucleolus organizer region, heterochromatin.

scholarly journals Deletion analysis of the selfish B chromosome, Paternal Sex Ratio (PSR), in the parasitic wasp Nasonia vitripennis.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 637-648 ◽  
Author(s):  
L W Beukeboom ◽  
J H Werren
Keyword(s):  
Sex Ratio ◽  
Dna Sequences ◽  
Parasitic Wasp ◽  
B Chromosome ◽  
Deletion Analysis ◽  
Functional Domains ◽  
Functional Domain ◽  
Paternal Chromosome ◽  
Nasonia Vitripennis ◽  
Paternal Sex Ratio

Abstract Paternal Sex Ratio (PSR) is a "selfish" B chromosome in the parasitoid wasp Nasonia vitripennis. It is transmitted via sperm, but causes supercondensation and destruction of the paternal chromosomes in early fertilized eggs. Because this wasp has haplodiploid sex determination, the effect of PSR is to convert diploid (female) eggs into haploid (male) eggs that carry PSR. Characterizing its genetic structure is a first step toward understanding mechanisms of PSR action. The chromosome is largely heterochromatic and contains several tandemly repeated DNA sequences that are not present on the autosomes. A deletion analysis of PSR was performed to investigate organization of repeats and location of functional domains causing paternal chromosome destruction. Deletion profiles using probes to PSR-specific repetitive DNA indicate that most repeats are organized in blocks on the chromosome. This study shows that the functional domains of PSR can be deleted, resulting in nonfunctional PSR chromosomes that are transmitted to daughters. A functional domain may be linked with the psr22 repeat, but function may also depend on abundance of PSR-specific repeats on the chromosome. It is hypothesized that the repeats act as a "sink" for a product required for proper paternal chromosome processing. Almost all deletion chromosomes remained either functional of nonfunctional in subsequent generations following their creation. One chromosome was exceptional in that it reverted from nonfunctionality to functionality in one lineage. Transmission rates of nonfunctional deletion chromosomes were high through haploid males, but low through diploid females.

scholarly journals Single and Double Infections with Wolbachia in the Parasitic Wasp Nasonia vitripennis Effects on Compatibility

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 961-972 ◽  
Author(s):  
Marie-Jeanne Perrot-Minnot ◽  
Li Rong Guo ◽  
John H Werren
Keyword(s):  
Genomic Dna ◽  
Rapid Development ◽  
Parasitic Wasp ◽  
Pcr Amplification ◽  
Bacterial Strains ◽  
Nasonia Vitripennis ◽  
Larval Diapause ◽  
Wide Range ◽  
Reproductive Incompatibility ◽  
Infected Line

Abstract Wolbachia are cytoplasmically inherited bacteria responsible for reproductive incompatibility in a wide range of insects. There has been little exploration, however, of within species Wolbachia polymorphisms and their effects on compatibility. Here we show that some strains of the parasitic wasp Nasonia vitripennis are infected with two distinct bacterial strains (A and B) whereas others are singly infected (A or B). Double and single infections are confirmed by both PCR amplification and Southern analysis of genomic DNA. Furthermore, it is shown that prolonged larval diapause (the overwintering stage of the wasp) of a double-infected strain can lead to stochastic loss of one or both bacterial strains. After diapause of a double-infected line, sublines were produced with AB, A only, B only or no Wolbachia. A and B sublines are bidirectionally incompatible, whereas males from AB lines are unidirectionally incompatible with females of A and B sublines. Results therefore show rapid development of bidirectional incompatibility within a species due to segregation of associated symbiotic bacteria.

scholarly journals The comparative biology of second sex ratio evolution within a natural population of a parasitic wasp, Nasonia vitripennis.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 385-396 ◽  
Author(s):  
S H Orzack
Keyword(s):  
Sex Ratio ◽  
Parasitic Wasp ◽  
Comparative Biology ◽  
Significant Heterogeneity ◽  
Regression Analyses ◽  
Nasonia Vitripennis ◽  
Second Sex ◽  
Sex Ratio Adjustment ◽  
Optimality Models ◽  
Isofemale Strains

Abstract Correlation and regression analyses indicate that isofemale strains extracted from a population of the parasitic wasp, Nasonia vitripennis, differ in the fit of their second sex ratios (those produced in previously parasitized hosts) to the predictions of the theory of optimal facultative sex ratio adjustment. Under the theory's simple assumptions about population structure, there is significant heterogeneity of fitnesses among the isofemale strains. The reasons underlying these types of heterogeneity must be understood before we can make statements about the nature of sex ratio evolution in this species. These results suggest that comparative analyses are essential for testing the qualitative predictions of optimality models.

Linkage Analysis of Sex Determination in Bracon sp. Near hebetor (Hymenoptera: Braconidae)

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 205-212
Author(s):  
Alisha K Holloway ◽  
Michael R Strand ◽  
William C Black ◽  
Michael F Antolin
Keyword(s):  
Linkage Group ◽  
Sex Determination ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Parasitic Wasp ◽  
Specific Pattern ◽  
Diploid Males ◽  
Phenotypic Marker ◽  
Group I ◽  
Sex Locus

Abstract To test whether sex determination in the parasitic wasp Bracon sp. near hebetor (Hymenoptera: Braconidae) is based upon a single locus or multiple loci, a linkage map was constructed using random amplified polymorphic DNA (RAPD) markers. The map includes 71 RAPD markers and one phenotypic marker, blonde. Sex was scored in a manner consistent with segregation of a single “sex locus” under complementary sex determination (CSD), which is common in haplodiploid Hymenoptera. Under haplodiploidy, males arise from unfertilized haploid eggs and females develop from fertilized diploid eggs. With CSD, females are heterozygous at the sex locus; diploids that are homozygous at the sex locus become diploid males, which are usually inviable or sterile. Ten linkage groups were formed at a minimum LOD of 3.0, with one small linkage group that included the sex locus. To locate other putative quantitative trait loci (QTL) for sex determination, sex was also treated as a binary threshold character. Several QTL were found after conducting permutation tests on the data, including one on linkage group I that corresponds to the major sex locus. One other QTL of smaller effect had a segregation pattern opposite to that expected under CSD, while another putative QTL showed a female-specific pattern consistent with either a sex-differentiating gene or a sex-specific deleterious mutation. Comparisons are made between this study and the indepth studies on sex determination and sex differentiation in the closely related B. hebetor.

Key aspects of the primary sex determination mechanism are conserved across the genus Drosophila

Development ◽  
1998 ◽  
Vol 125 (16) ◽  
pp. 3259-3268 ◽  
Author(s):  
J.W. Erickson ◽  
T.W. Cline
Keyword(s):  
Sex Determination ◽  
Rapid Onset ◽  
Amino Acid Identity ◽  
Bzip Transcription Factor ◽  
Regulatory Sequence ◽  
Tightly Coupled ◽  
Pole Cells ◽  
High Level ◽  
Key Aspects ◽  
Determination Mechanism

In D. melanogaster, a set of ‘X:A numerator genes’, which includes sisterlessA (sisA), determines sex by controlling the transcription of Sex-lethal (Sxl). We characterized sisA from D. pseudoobscura and D. virilis and studied the timing of sisA and Sxl expression with single cell-cycle resolution in D. virilis, both to guide structure-function studies of sisA and to help understand sex determination evolution. We found that D. virilis sisA shares 58% amino acid identity with its melanogaster ortholog. The identities confirm sisA as an atypical bZIP transcription factor. Although virilis sisA can substitute for melanogaster sisA, the protein is not fully functional in a heterologous context. The putative sisA regulatory sequence CAGGTAG is a potential ‘numerator box,’ since it is shared with the other strong X:A numerator gene, sisB, and its target, SxlPe. Temporal and spatial features of sisA and SxlPe expression are strikingly conserved, including rapid onset and cessation of transcription in somatic nuclei, early cessation of sisA transcription in budding pole cells and persistent high-level sisA expression in yolk nuclei. Expression of sisA and Sxl is as tightly coupled in virilis as it is in melanogaster. Taken together, these data indicate that the same primary sex determination mechanism exists throughout the genus Drosophila.

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