Sex Drive
Mostrando 13-24 de 41 artigos, teses e dissertações.
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13. Causes of Sex Ratio Bias May Account for Unisexual Sterility in Hybrids: A New Explanation of Haldane's Rule and Related Phenomena
Unisexual hybrid disruption can be accounted for by interactions between sex ratio distorters which have diverged in the species of the hybrid cross. One class of unisexual hybrid disruption is described by Haldane's rule, namely that the sex which is absent, inviable or sterile is the heterogametic sex. This effect is mainly due to incompatibility between X
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14. Polymorphism for Y-Linked Suppressors of Sex-Ratio in Two Natural Populations of Drosophila Mediopunctata
In several Drosophila species there is a trait known as ``sex-ratio'': males carrying certain X chromosomes (called ``SR'') produce female biased progenies due to X-Y meiotic drive. In Drosophila mediopunctata this trait has a variable expression due to Y-linked suppressors of sex-ratio expression, among other factors. There are two types of Y chromosomes (s
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15. Sex Chromosome Meiotic Drive in DROSOPHILA MELANOGASTER Males
In Drosophila melanogaster males, deficiency for X heterochromatin causes high X-Y nondisjunction and skewed sex chromosome segregation ratios (meiotic drive). Y and XY classes are recovered poorly because of sperm dysfunction. In this study it was found that X heterochromatic deficiencies disrupt recovery not only of the Y chromosome but also of the X and
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16. ``sex Ratio'' Meiotic Drive in Drosophila Testacea
We document the occurrence of ``sex ratio'' meiotic drive in natural populations of Drosophila testacea. ``Sex ratio'' males sire >95% female offspring. Genetic analysis reveals that this effect is due to a meiotically driven X chromosome, as in other species of Drosophila in which ``sex ratio'' has been found. In contrast to other drosophilids, the ``sex ra
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17. Experimental and Theoretical Analysis of the "Sex-Ratio" Polymorphism in DROSOPHILA PSEUDOOBSCURA
The Sex-ratio chromosome (SR) is a widespread, multiply inverted rearrangement of the X chromosome present in several species of Drosophila. Male carriers transmit mostly X-bearing sperm. In the absence of strong counteracting selection, SR is expected to increase rapidly to fixation, causing extinction. The present study incorporates a selection-components
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18. Sex Chromosome Meiotic Drive Systems in DROSOPHILA MELANOGASTER I. Abnormal Spermatid Development in Males with a Heterochromatin-Deficient X Chromosome (sc4sc8)
The meiotic drive characteristics of the In(1)sc4Lsc8R/Y system have been examined by genetic analysis and by light and electron microscopy. sc4sc8/Y males show a direct correlation between nondisjunction frequency and meiotic drive. Temperature-shift experiments reveal that the temperature-sensitive period for nondisjunction is at meiosis, whereas that for
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19. Fix for low sex drive puts reporters in a bad patch
Stories about the testosterone patch are a case study in misleading media coverage
BMJ Publishing Group Ltd..
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20. Sex defines the age dependence of endogenous ACTH-cortisol dose responsiveness
Sex influences adrenal glucocorticoid responses to ACTH in experimental animals. Whether similar sex differences operate in humans is unknown. To test this notion, we estimated ACTH-cortisol dose-response properties analytically in 48 healthy adults (n = 22 women, n = 26 men), ages 18–77 yr, body mass index (BMI) 18–32 kg/m2, previously studied at two me
American Physiological Society.
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21. Sex-specific control of Drosophila melanogaster yolk protein 1 gene expression is limited to transcription.
The sex of Drosophila melanogaster is determined by a hierarchy of genes. The ultimate targets of this regulatory hierarchy are the genes encoding terminal differentiation products of one sex. For one of the best-characterized target genes, that encoding female-specific yolk protein 1 (YP1), sex-specific transcriptional controls have been clearly demonstrate
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22. Transposition of the Responder Element (Rsp) of the Segregation Distorter System (Sd) to the X Chromosome in Drosophila Melanogaster
In order to test whether the meiotic drive system Segregation distorter (SD) can operate on the X chromosome to exclude it from functional sperm, we have transposed the Responder locus (Rsp) to this element. This was accomplished by inducing detachments of a compound-X chromosome in females carrying a Y chromosome bearing a Rsp(s) allele. Six Responder-sensi
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23. X-4 Translocations and Meiotic Drive in Drosophila melanogaster Males: Role of Sex Chromosome Pairing
Males carrying certain X-4 translocations exhibit strongly skewed sperm recovery ratios. The XP4D half of the translocation disjoins regularly from the Y chromosome and the 4PXD half disjoins regularly from the normal 4. Yet the smaller member of each bivalent is recovered in excess of its pairing partner, apparently due to differential gametic lethality. C
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24. Sex Ratio Distortion Caused by Meiotic Drive in a Mosquito, Culex pipiens L
A genetic factor, distorter (d), has been discovered that upsets the normal sex ratio of 1:1 and results in a large excess of males in Culex pipiens. The effect can be explained by a sex-linked, recessive gene. Males homozygous for the gene (Md/md) produce few female offspring; the effect is not due to postzygotic mortality. During the first meiotic division