Correlation of intercentromeric distance, mosaicism, and sexual phenotype: Molecular localization of breakpoints in isodicentric Y chromosomes

ABSTRACT Abdominal bristle selection lines (three high and three low) and controls were founded from a marked homozygous line to measure the contribution of sex-linked "mutations" to selection response. Two of the low lines exhibited a period of rapid response to selection in females, but not in males. There were corresponding changes in female variance, in heritabilities in females, in the sex ratio (a deficiency of females) and in fitness, as well as the appearance of a mutant phenotype in females of one line. All of these changes were due to bb alleles (partial deficiencies for the rRNA tandon) in the X chromosomes of these lines, while the Y chromosomes remained wild-type bb+. We argue that the bb alleles arose by unequal crossing over in the rRNA tandon.—A prediction of this hypothesis is that further changes can occur in the rRNA tandon as selection is continued. This has now been shown to occur.—Our minimum estimate of the rate of occurrence of changes at the rRNA tandon is 3 × 10-4. As this is substantially higher than conventional mutation rates, the questions of the mechanisms and rates of origin of new quantitative genetic variation require careful re-examination.

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Y Chromosomes in Male Psychiatric Patients above 180 cm. Tall

The British Journal of Psychiatry ◽

10.1192/bjp.114.517.1589 ◽

1968 ◽

Vol 114 (517) ◽

pp. 1589-1590 ◽

Cited By ~ 15

Author(s):

Johannes Nielsen

Keyword(s):

Chromosome Number ◽

State Hospital ◽

Psychiatric Patients ◽

Chromosome Analysis ◽

Y Chromosomes ◽

Sex Chromatin ◽

Male Patients

All male patients above 180 cm. tall who were resident in the Århus State Hospital on 13 April, 1966, were registered: they numbered 42 out of the total of 440 resident males (8 · 1 per cent.). One patient, a 78-year-old man, died before chromosome analysis was made. Sex-chromatin analysis was made on Feulgenstained buccal smears and chromosome analysis was made on leucocyte cultures according to the method described by Moorhead et al. (1960), slightly modified. Not less than 25 metaphases were counted, at least 15 metaphases with the modal figure and all metaphases with a chromosome number deviating from the modal figures were analysed.

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Reciprocal recombination and the evolution of the ribosomal gene family of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/122.3.617 ◽

1989 ◽

Vol 122 (3) ◽

pp. 617-624 ◽

Cited By ~ 1

Author(s):

S M Williams ◽

J A Kennison ◽

L G Robbins ◽

C Strobeck

Keyword(s):

Drosophila Melanogaster ◽

Gene Family ◽

Ribosomal Rna ◽

Natural Populations ◽

Ribosomal Gene ◽

Gene Region ◽

Ribosomal Rna Gene ◽

Reciprocal Recombination ◽

Y Chromosomes ◽

Length Polymorphisms

Abstract The role of reciprocal recombination in the coevolution of the ribosomal RNA gene family on the X and Y chromosomes of Drosophila melanogaster was assessed by determining the frequency and nature of such exchange. In order to detect exchange events within the ribosomal RNA gene family, both flanking markers and restriction fragment length polymorphisms within the tandemly repeated gene family were used. The vast majority of crossovers between flanking markers were within the ribosomal RNA gene region, indicating that this region is a hotspot for heterochromatic recombination. The frequency of crossovers within the ribosomal RNA gene region was approximately 10(-4) in both X/X and X/Y individuals. In conjunction with published X chromosome-specific and Y chromosome-specific sequences and restriction patterns, the data indicate that reciprocal recombination alone cannot be responsible for the observed variation in natural populations.

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Sex Differences Are Here to Stay: Relevance to Prenatal Care

Journal of Clinical Medicine ◽

10.3390/jcm10133000 ◽

2021 ◽

Vol 10 (13) ◽

pp. 3000

Author(s):

Amy M. Inkster ◽

Icíar Fernández-Boyano ◽

Wendy P. Robinson

Keyword(s):

Sex Differences ◽

Pregnancy Complications ◽

Pregnancy Loss ◽

Gonadal Steroid Hormones ◽

Perinatal Complications ◽

Spontaneous Preterm Birth ◽

Prenatal Diagnostic ◽

Y Chromosomes ◽

Offspring Sex ◽

Differential Gene

Sex differences exist in the incidence and presentation of many pregnancy complications, including but not limited to pregnancy loss, spontaneous preterm birth, and fetal growth restriction. Sex differences arise very early in development due to differential gene expression from the X and Y chromosomes, and later may also be influenced by the action of gonadal steroid hormones. Though offspring sex is not considered in most prenatal diagnostic or therapeutic strategies currently in use, it may be beneficial to consider sex differences and the associated mechanisms underlying pregnancy complications. This review will cover (i) the prevalence and presentation of sex differences that occur in perinatal complications, particularly with a focus on the placenta; (ii) possible mechanisms underlying the development of sex differences in placental function and pregnancy phenotypes; and (iii) knowledge gaps that should be addressed in the development of diagnostic or risk prediction tools for such complications, with an emphasis on those for which it would be important to consider sex.

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