Chromosome studies on normal males in 16 families with the marker X chromosome

2008 ◽  
Vol 26 (2) ◽  
pp. 166-167 ◽  
Author(s):  
P. A. Venter ◽  
D. J. Coetzee ◽  
J. Wilmot ◽  
D. Behari ◽  
S. A. Battson ◽  
...  
Keyword(s):  
X Chromosome ◽  
Normal Males

Detrimental effects of two active X chromosomes on early mouse development

Development ◽  
1990 ◽  
Vol 109 (1) ◽  
pp. 189-201 ◽  
Author(s):  
N. Takagi ◽  
K. Abe
Keyword(s):  
X Chromosome ◽  
Distal Segment ◽  
Translocation Chromosome ◽  
Mouse Development ◽  
X Chromosomes ◽  
Developmental Abnormalities ◽  
Inactivation Center ◽  
Normal Males ◽  
Early Mouse ◽  
Embryonic Ectoderm

Matings between female mice carrying Searle's translocation, T(X;16)16H, and normal males give rise to chromosomally unbalanced zygotes with two complete sets of autosomes, one normal X chromosome and one X16 translocation chromosome (XnX16 embryos). Since X chromosome inactivation does not occur in these embryos, probably due to the lack of the inactivation center on X16, XnX16 embryos are functionally disomic for the proximal 63% of the X chromosome and trisomic for the distal segment of chromosome 16. Developmental abnormalities found in XnX16 embryos include: (1) growth retardation detected as early as stage 9, (2) continual loss of embryonic ectoderm cells either by death or by expulsion into the proamniotic cavity, (3) underdevelopment of the ectoplacental cone throughout the course of development, (4) very limited, if any, mesoderm formation, (5) failure in early organogenesis including the embryo, amnion, chorion and yolk sac. Death occurred at 10 days p.c. Since the combination of XO and trisomy 16 does not severely affect early mouse development, it is likely that regulatory mechanisms essential for early embryogenesis do not function correctly in XnX16 embryos due to activity of the extra X chromosome segment of X16.

Letter to the Editor

PEDIATRICS ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 153-154
Author(s):  
Frederick Hecht ◽  
Thomas W. Glover ◽  
Barbara Kaiser-Hecht
Keyword(s):  
X Chromosome ◽  
Fragile X ◽  
Fragile Sites ◽  
Normal Male ◽  
Letter To The Editor ◽  
Cytogenetic Studies ◽  
Comprehensive Survey ◽  
Normal Males

The commentary on "Fragile Sites on Chromosomes" consisted of two pages of text.1 It was not a "comprehensive survey." Rather it was meant simply to provide a passing perspective on this rapidly progressing area: fragile sites. Normal Males with Fragile X. In the commentary we cited the initial report2 of the "fragile X in a normal male." The second report3 of a normal male with the fragile X appeared subsequently. Both reports are brief. It is entirely possible that both reports are wrong. These males may prove retarded when carefully tested and compared with their normal relatives. More detailed cytogenetic studies may show that these males do not really have the fragile X chromosome.

scholarly journals Expression and Linkage of Genes for X-linked Hemophilias A and B in the Dog

Blood ◽  
1973 ◽  
Vol 41 (4) ◽  
pp. 577-585 ◽  
Author(s):  
K. M. Brinkhous ◽  
P. D. Davis ◽  
John B. Graham ◽  
W. Jean Dodds
Keyword(s):  
X Chromosome ◽  
Hemophilia A ◽  
Factor Ix ◽  
Neonatal Lethality ◽  
Plasma Factor ◽  
Normal Males ◽  
Linkage Of Genes ◽  
Linkage Distance ◽  
Antihemophilic Factor ◽  
Preferential Inactivation

Abstract The linkage distance on the X chromosome between the genes for hemophilia A (classic hemophilia) and B (PTC deficiency, Christmas disease) was estimated directly by breeding two strains of dogs, each segregating for a different type of hemophilia. Gene expression was determined by bioassays of plasma factor VIII (antihemophilic factor) and factor IX (PTC, Christmas factor). Double heterozygotes in repulsion for both hemophilia A and B could be readily identified by intermediate plasma levels of both procoagulants. There was no evidence of a tendency toward preferential inactivation of the paternally derived X chromosome, and the procoagulant levels showed that random inactivation had occurred at both loci. When double heterozygotes were bred against normal males or males with hemophilia A and B, the progeny that resulted indicated that the genes recombined freely. Thus, the genes are at least 50 map units apart. The phenotypes of five new hemophilic genotypes are described as a result of the various crossbreedings, including males with double hemophilia AB. When both hemophilia genes are in the coupling phase, there is evidence of increased intrauterine or neonatal lethality in males. The data from this study, along with that on gene linkage of human hemophilia A and B, provide support for the thesis of homology of the X chromosome during speciation.

MATERNALLY INFLUENCED EMBRYONIC LETHALITY: ALLELE SPECIFIC GENETIC RESCUE AT A FEMALE FERTILITY LOCUS IN DROSOPHILA MELANOGASTER

1976 ◽  
Vol 18 (4) ◽  
pp. 773-781 ◽  
Author(s):  
Patricia Romans ◽  
R. B. Hodgetts ◽  
D. Nash
Keyword(s):  
Drosophila Melanogaster ◽  
Embryonic Development ◽  
X Chromosome ◽  
Maternal Effect ◽  
Female Offspring ◽  
The Other ◽  
Genetic Rescue ◽  
Homozygous Mutant ◽  
Allele Specific ◽  
Normal Males

A new locus, mel(l)R1, with a maternal effect on embryonic development, has been mapped at about 0.5 on the X chromosome of Drosophila melanogaster and localized cytologically between bands 2D6 and 3A1. Genotypically mutant embryos die if produced by homozygous mutant females but survive if produced by heterozygous females. Two mutant alleles have been isolated. One of these is genetically rescuable: when homozygous mutant females are mated to mutant males, all the embryos die, but when these females are mated to normal males, female offspring are produced. The other allele is not rescuable. Genetic rescue is dominant at this locus since females heterozygous for the two mutant alleles produce female offspring in crosses to normal males.

Taurodontism in 47,XXY Males: An Effect of the Extra X Chromosome on Root Development

1988 ◽  
Vol 67 (2) ◽  
pp. 501-502 ◽  
Author(s):  
J. Varrela ◽  
L. Alvesalo
Keyword(s):  
X Chromosome ◽  
Root Development ◽  
Root Formation ◽  
Population Sample ◽  
Third Molars ◽  
Lower Jaw ◽  
Mandibular Molar ◽  
Permanent Molars ◽  
Males And Females ◽  
Normal Males

Effects of an extra X chromosome on root development were studied in males with a 47, XXY chromosome constitution. Occurrence of taurodontism in the permanent molars of the lower jaw was noted from orthopantomograms of 30 Finnish 47,XXY males, 16 of their first-degree relatives, and a sample of 157 normal males and females. Nine, or 30%, or the 47, XXY males had at least one mandibular molar which was classified as taurodont. Only hypotaurodont teeth were found, and the teeth affected were all either second or third molars. None of the control relatives showed taurodontism. In the population sample, four individuals, or 2.5%, had taurodont teeth. A change in the mitotic activity of the cells of the developing teeth is one possible factor that can affect root formation leading to the development of taurodontism.

Steroid Sulphatase Deficiency: Identification of Heterozygotes Using Hydrolysis of Dehydroepiandrosterone Sulphate by Peripheral Leucocytes

1996 ◽  
Vol 33 (3) ◽  
pp. 219-226 ◽  
Author(s):  
E I Lowis ◽  
R E Oakey
Keyword(s):  
X Chromosome ◽  
Dosage Compensation ◽  
Gene Dosage ◽  
Ovarian Cycle ◽  
Dehydroepiandrosterone Sulphate ◽  
Steroid Sulphatase ◽  
Normal Males ◽  
Mononuclear Leucocytes ◽  
Hydrolysis Of ◽  
Recessive Ichthyosis

Diagnosis of X-linked recessive ichthyosis, which is expressed only in males, can readily be made by measurement of leucocyte steroid sulphatase activity. However, because the gene for steroid sulphatase activity partly escapes from the process of X-chromosome inactivation associated with gene dosage compensation, identification of heterozygotes (females) is more difficult. We have measured the steroid sulphatase (by hydrolysis of dehydroepiandrosterone sulphate) and β-glucuronidase (by hydrolysis of methylumbelliferyl glucuronide) activities in leucocytes from 18 heterozygotes, 100 normal females, 100 normal males and 11 affected subjects. When the ratio of the activities of steroid sulphatase and β-glucuronidase in mixed leucocytes was plotted as a function of the steroid sulphatase activity, 85% heterozygotes were distinguished from normal females. Measurement of steroid sulphatase activity alone with these cells enabled identification of 78% heterozygotes. Measurements on mononuclear leucocytes were much less effective. Thrombocytes showed 1% of the steroid sulphatase activity of leucocytes. In females, leucocyte steroid sulphatase activity was independent of the stage of the ovarian cycle at which the cells were collected.

“Fragile X” Chromosome in Normal Males

2008 ◽  
Vol 20 (1) ◽  
pp. 78-78 ◽  
Author(s):  
Patricia N. Howard-Peebles
Keyword(s):  
X Chromosome ◽  
Fragile X ◽  
Normal Males

Fragile X Chromosome in normal males

1983 ◽  
Vol 14 (4) ◽  
pp. 795-796 ◽  
Author(s):  
M. G. Daker
Keyword(s):  
X Chromosome ◽  
Fragile X ◽  
Normal Males

scholarly journals The Amino-Terminal Region of Drosophila MSL1 Contains Basic, Glycine-Rich, and Leucine Zipper-Like Motifs That Promote X Chromosome Binding, Self-Association, and MSL2 Binding, Respectively

2005 ◽  
Vol 25 (20) ◽  
pp. 8913-8924 ◽  
Author(s):  
Fang Li ◽  
David A. D. Parry ◽  
Maxwell J. Scott
Keyword(s):  
X Chromosome ◽  
Leucine Zipper ◽  
Terminal Region ◽  
Amino Terminal ◽  
High Affinity ◽  
Msl Complex ◽  
Self Association ◽  
Normal Males ◽  
Chromosome Binding

ABSTRACT In Drosophila melanogaster, X chromosome dosage compensation is achieved by doubling the transcription of most X-linked genes. The male-specific lethal (MSL) complex is required for this process and binds to hundreds of sites on the male X chromosome. The MSL1 protein is essential for X chromosome binding and serves as a central scaffold for MSL complex assembly. We find that the amino-terminal region of MSL1 binds to hundreds of sites on the X chromosome in normal males but only to approximately 30 high-affinity sites in the absence of endogenous MSL1. Binding to the high-affinity sites requires a basic motif at the amino terminus that is conserved among Drosophila species. X chromosome binding also requires a conserved leucine zipper-like motif that binds to MSL2. A glycine-rich motif between the basic and leucine-zipper-like motifs mediates MSL1 self-association in vitro and binding of the amino-terminal region of MSL1 to the MSL complex assembled on the male X chromosome. We propose that the basic region may mediate DNA binding and that the glycine-rich region may promote the association of MSL complexes to closely adjacent sites on the X chromosome.

scholarly journals Role of the male specific lethal (msl) Genes in Modifying the Effects of Sex Chromosomal Dosage in Drosophila

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 249-268 ◽  
Author(s):  
Utpal Bhadra ◽  
Manika Pal-Bhadra ◽  
James A Birchler
Keyword(s):  
X Chromosome ◽  
Wide Distribution ◽  
Individual Gene ◽  
Genome Wide ◽  
Nucleation Sites ◽  
Inverse Effect ◽  
Male Specific Lethal ◽  
Msl Complex ◽  
Normal Males ◽  
Male Specific

Abstract Immunostaining of chromosomes shows that the male-specific lethal (MSL) proteins are associated with all female chromosomes at a low level but are sequestered to the X chromosome in males. Histone-4 Lys-16 acetylation follows a similar pattern in normal males and females, being higher on the X and lower on the autosomes in males than in females. However, the staining pattern of acetylation and the mof gene product, a putative histone acetylase, in msl mutant males returns to a uniform genome-wide distribution as found in females. Gene expression on the autosomes correlates with the level of histone-4 acetylation. With minor exceptions, the expression levels of X-linked genes are maintained with either an increase or decrease of acetylation, suggesting that the MSL complex renders gene activity unresponsive to H4Lys16 acetylation. Evidence was also found for the presence of nucleation sites for association of the MSL proteins with the X chromosome rather than individual gene binding sequences. We suggest that sequestration of the MSL proteins occurs in males to nullify on the autosomes and maintain on the X, an inverse effect produced by negatively acting dosage-dependent regulatory genes as a consequence of the evolution of the X/Y sex chromosomal system.

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