A correlation between B chromosome frequency and sex ratio in Exochomus quadripustulatus

Chromosoma ◽  
1988 ◽  
Vol 96 (5) ◽  
pp. 376-381 ◽  
Author(s):  
S. A. Henderson
Keyword(s):  
Sex Ratio ◽  
B Chromosome ◽  
Exochomus Quadripustulatus

scholarly journals The origin of a selfish B chromosome triggering paternal sex ratio in the parasitoid wasp Trichogramma kaykai

2009 ◽  
Vol 276 (1676) ◽  
pp. 4149-4154 ◽  
Author(s):  
Joke J. F. A. Van Vugt ◽  
Hans de Jong ◽  
Richard Stouthamer
Keyword(s):  
Sex Ratio ◽  
Dna Analysis ◽  
Parasitoid Wasp ◽  
B Chromosome ◽  
Satellite Repeat ◽  
Paternal Genome ◽  
Major Satellite ◽  
Similar Mode ◽  
Different Origins ◽  
Paternal Sex Ratio

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 .

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.

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

Genome ◽  
2003 ◽  
Vol 46 (4) ◽  
pp. 580-587 ◽  
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.

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.

Hermaphroditism can compensate for the sex ratio in the Astyanax scabripinnis species complex (Teleostei: Characidae): expanding the B chromosome study model

2017 ◽  
Vol 27 (3) ◽  
pp. 681-689 ◽  
Author(s):  
Diana Cornelio ◽  
Jonathan Pena Castro ◽  
Mateus Henrique Santos ◽  
Marcelo Ricardo Vicari ◽  
Mara Cristina de Almeida ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Species Complex ◽  
B Chromosome ◽  
Chromosome Study ◽  
Astyanax Scabripinnis

Die unbehandelten Kranken: Ältere Männer mit Depression

2008 ◽  
Vol 27 (07) ◽  
pp. 617-619 ◽  
Author(s):  
M. Wittmann ◽  
E. Haen ◽  
H. Spießl ◽  
H. Hausner
Keyword(s):  
Sex Ratio ◽  
Epidemiologische Studien

ZusammenfassungZahlreiche epidemiologische Studien zeigen, dass sich das Geschlechterverhältnis der Prävalenz depressiver Erkrankungen ab der 6. Lebensdekade – also nach der weiblichen Menopause – wieder annähert. Wir haben untersucht, ob sich dieser epidemiologische Effekt auch in der stationären Versorgung abbildet. Unter Verwendung der AGATE-Stichtagsdaten der Jahre 2000 bis 2004, wurde der Zusammenhang zwischen Geschlecht und Alter bei stationär behandelten depressiven Patienten analysiert. Der Zusammenhang zwischen Geschlechterverhältnis und dem Alter wurde mithilfe des Korrelationskoeffizienten nach Spearman sowie mit χ2-Test untersucht. In der 5. und 6. Lebensdekade lag die Sex-Ratio F/M bei 1,7:1, sie stieg in der 7. Dekade auf 2,2:1 und in der 8. Dekade auf 2,6:1 an. Anders als aufgrund epidemiologischer Studien zu erwarten wäre, nähert sich in der stationär psychiatrischen Versorgung das Verhältnis depressiver Patienten im Alter nicht an. Depressive ältere Männer sind also im stationären Versorgungssystem unterrepräsentiert.

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