Phenotypic fitness effects of the selfish B chromosome, paternal sex ratio (PSR) in the parasitic waspNasonia vitripennis

This study uses molecular and cytogenetic methods to determine the origin of a B chromosome in some males of the wasp Trichogramma kaykai . This so-called paternal sex ratio (PSR) chromosome transmits only through sperm and shortly after fertilization triggers degeneration of the paternal genome, while keeping itself intact. The resulting embryos develop into haploid B-chromosome-carrying males. Another PSR chromosome with a very similar mode of action is found in the distantly related wasp Nasonia vitripennis and its origin was traced by transposon similarity to the genus Trichomalopsis , which is closely related to Nasonia . To determine whether both PSR chromosomes have a similar origin we aimed to reveal the origin of the Trichogramma PSR chromosome. Using fluorescent in situ hybridization, we discovered a major satellite repeat on the PSR chromosome, the 45S ribosomal DNA. Analysis of the internal transcribed spacer 2 (ITS2) of this repeat showed the presence of multiple ITS2 sequences on the PSR chromosome resembling either the ITS2 of T. oleae or of T. kaykai . We therefore conclude that the Trichogramma PSR chromosome originates from T. oleae or a T. oleae -like species. Our results are consistent with different origins for the PSR chromosomes in Trichogramma and Nasonia .

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Transcriptome Profiling of Nasonia vitripennis Testis Reveals Novel Transcripts Expressed from the Selfish B Chromosome, Paternal Sex Ratio

G3 Genes|Genome|Genetics ◽

10.1534/g3.113.007583 ◽

2013 ◽

Vol 3 (9) ◽

pp. 1597-1605 ◽

Cited By ~ 30

Author(s):

Omar S. Akbari ◽

Igor Antoshechkin ◽

Bruce A. Hay ◽

Patrick M. Ferree

Keyword(s):

Sex Ratio ◽

Transcriptome Profiling ◽

B Chromosome ◽

Nasonia Vitripennis ◽

Novel Transcripts ◽

Paternal Sex Ratio

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Cytogenetic analysis of the paternal sex ratio chromosome of Nasonia vitripennis

Genome ◽

10.1139/g93-020 ◽

1993 ◽

Vol 36 (1) ◽

pp. 157-161 ◽

Cited By ~ 22

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.

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The paternal sex ratio chromosome in the parasitic wasp Trichogramma kaykai condenses the paternal chromosomes into a dense chromatin mass

Genome ◽

10.1139/g03-044 ◽

2003 ◽

Vol 46 (4) ◽

pp. 580-587 ◽

Cited By ~ 18

Author(s):

Joke F.A van Vugt ◽

Merijn Salverda ◽

J Hans de Jong ◽

Richard Stouthamer

Keyword(s):

Sex Ratio ◽

Parasitic Wasp ◽

Parasitoid Wasp ◽

B Chromosome ◽

The Other ◽

Paternal Chromosome ◽

Paternal Genome ◽

Obvious Similarity ◽

Dense Chromatin ◽

Paternal Sex Ratio

A recently discovered B chromosome in the parasitoid wasp Trichogramma kaykai was found to be transmitted through males only. Shortly after fertilization, this chromosome eliminates the paternal chromosome set leaving the maternal chromosomes and itself intact. Consequently, the sex ratio in these wasps is changed in favour of males by modifying fertilized diploid eggs into male haploid offspring. In this study, we show that in fertilized eggs at the first mitosis the paternal sex ratio (PSR) chromosome condenses the paternal chromosomes into a so-called paternal chromatin mass (PCM). During this process, the PSR chromosome is morphologically unaffected and is incorporated into the nucleus containing the maternal chromosomes. In the first five mitotic divisions, 67% of the PCMs are associated with one of the nuclei in the embryo. Furthermore, in embryos with an unassociated PCM, all nuclei are at the same mitotic stage, whereas 68% of the PCM-associated nuclei are at a different mitotic phase than the other nuclei in the embryo. Our observations reveal an obvious similarity of the mode of action of the PSR chromosome in T. kaykai with that of the PSR-induced paternal genome loss in the unrelated wasp Nasonia vitripennis.Key words: paternal sex ratio, PSR, Trichogramma kaykai, B chromosome, paternal chromatin mass, embryogenesis.

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

Genetics ◽

10.1093/genetics/133.3.637 ◽

1993 ◽

Vol 133 (3) ◽

pp. 637-648 ◽

Cited By ~ 2

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.

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Parental care and adaptive brood sex ratio manipulation in birds

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2001.0924 ◽

2002 ◽

Vol 357 (1419) ◽

pp. 363-372 ◽

Cited By ~ 85

Author(s):

D. Hasselquist ◽

B. Kempenaers

Keyword(s):

Sex Ratio ◽

Parental Care ◽

Statistical Power ◽

Molecular Techniques ◽

Fitness Effects ◽

Primary Sex Ratio ◽

Brood Sex Ratio ◽

Power Studies ◽

High Statistical Power

Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against non–significant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex–differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.

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