Chromosomal Sex Determination Research Articles

XX/XY-Sex Chromosomes in Gekko gecko (Sauria, Reptilia)

The mitotic karyotype, chromosomal banding patterns and male meiotic chromosomes of Gekko gecko were studied in differentially stained preparations obtained from bone marrow and testes. A chromosome number of 38 was found with a heteromorphic chromosome pair in the male sex, which indicates a XX/XY-mechanism of chromosomal sex determination. The Y-chromosome was found to be larger than the X-chromosome.

Identification of a male determinant on the X chromosome of housefly (Musca domestica L.) populations in South-East England

SUMMARYHouseflies collected from eight pig-breeding farms were used to investigate the nature of sex determinants in fly populations of South-East England. Earlier observations had shown that their sex determination mechanism was not of the standard (XX females, XY males) type.Most flies of both sexes were XX; the male determining Y chromosome of standard populations was rare. Test-crosses to females of standard multimarked strains and crosses using aneuploid (OX) flies identified two dominant male determinants, one on autosome 3 (M III) and another on the X chromosome (Xm), and provided the first demonstration in this species of an active involvement of the X chromosome in sex determination. A small secondary constriction on X appeared to indicate reliably the presence of Xm. Most individuals in field populations were Xm homozygotes, implying the presence of an unlocated female determinant F,† epistatic to Xm and M III.M III was less common and differed in frequency between samples. Its increased frequency in a strain selected in the laboratory with the pyrethroid insecticide permethrin might be due either to genetic drift, or to linkage between M III and a gene on autosome 3 that confers resistance to pyrethroids in houseflies.

Single-copy DNA sequences specific for the human Y chromosome.

Detailed studies of the role of the mammalian Y chromosome in primary sex determination are limited by the lack of available specific markers and by the fragmentary knowledge of its molecular organization. Y-derived unique DNA sequences could provide powerful analytical tools to probe directly the structure of the Y chromosome and provide a means of searching for specific expressed sequences. We report here the construction of a partial cosmid library of the human Y chromosome. From independent clones we have isolated 30 unrelated DNA probes that are free of highly repetitive sequences, and have examined their reaction pattern on male and female genomic blots. Of the 30 probes tested, six were specific for the Y chromosome. In addition, four probes gave a male-female differential hybridization pattern and the remaining 20, although Y-derived, reacted similarly with both male and female DNA.

The chromosomes and sex-determination of some actinotrichid taxa (Acari), with special reference to Eriophyidae

Abstract The chromosome number and sex-determination of 15 actinotrichid species belonging to Eriophyidae, Tenuipalpidae, Tetranychidae, Tydeidae and Epidermoptidae were determined. The chromosomes of most species examined are few in number and roughly similar in size, shape and behaviour. It is believed that all species have holokinetic chromosomes. Haplo-diploidy was shown to be the mechanism of sex-determination in the Eriophyidae, since all 8 species examined were found to have eggs with n = 2 and 2n = 4 chromosomes. Myialges pari Fain is the first psoroptid species examined on karyotype. The occurrence of eggs with n = 8 and 2n = 16 chromosomes is evidence for the existence of haplo-diploidy in the order of the Psoroptina.

Evolutionary conservation of sex specific DNA sequences.

A family of DNA sequences which appears to be limited to eukaryotes is concentrated on the sex-determining chromosomes of species as widely separated evolutionarily as snakes and mammals. The significance of this distribution is presently seen in terms of the function of these sequences in cycles of chromosome condensation and decondensation involved in the control of gene expression. Thus, their concentration on the sex chromosomes is interpreted in the context of the evolution of such chromosomes which, it is hypothesised, involves the superimposition of the controls of the dominant sex-determining gene(s) upon the entire linkage group. This would result in the prevention of the large majority of its genes from having effects upon the phenotype and, in consequence, lead to their mutation to functionlessness at the maximum rate.

Sex reversal in the mouse (Mus musculus) is caused by a recurrent nonreciprocal crossover involving the X and an aberrant Y chromosome

Satellite DNA (Bkm) from the W sex-determining chromosome of snakes, which is related to sequences on the mouse Y chromosome, has been used to analyze the DNA and chromosomes of sex-reversed (Sxr) XXSxr male mice. Such mice exhibit a male-specific Southern blot Bkm hybridization pattern, consistent with the presence of Y-chromosome DNA. In situ hybridization of Bkm to chromosomes of XXSxr mice shows an aberrant concentration of related sequences on the distal terminus of a large mouse chromosome. The XYSxr carrier male, however, shows a pair of small chromosomes, which are presumed to be aberrant Y derivatives. Meiosis in the XYSxr mouse involves transfer of chromatin rich in Bkm-related DNA from the Y-Y1 complex to the X distal terminus. We suggest that this event is responsible for the transmission of the Sxr trait.

Conserved repeated DNA sequences in vertebrate sex chromosomes.

Satellite DNA isolated from female Elapid snakes contains nucleotide sequences which are quantitatively derived from the W sex-determining chromosome. Certain of these sequences are highly conserved in vertebrates, including mammals, where they are arranged in a sex-specific pattern in Southern blots. Sex reversed mice (Sxr) show a DNA arrangement of these sequences in conformity with their phenotypic sex, suggesting that this DNA is closely connected with the determination of sex. In situ hybridization of the snake sequences with mouse chromosomes reveals a concentration of related DNA at the proximal tip of the mouse Y chromosome. This possible nature and significance of these observations is discussed.

Conserved sex-chromosome-associated nucleotide sequences in eukaryotes.

Sexual differentiation is probably the most important aspect of the many processes of differentiation that underlie the development of the adult organism. In principle, it is likely that the determination of primary sex will involve mechanisms related to those that control other aspects of differentiation. In our work on the structure of sex-determining chromosomes in primitive vertebrates, we have identified and recovered a repeated DNA from snakes that appears as a satellite fraction in female DNA. This satellite is interspersed with other more complex DNA throughout the length of the sex-determining W chromosome, and both are recovered together by ultracentrifugation in heavy-metal-containing isopycnic gradients. It is these more complex sequence elements that we believe are responsible for the phenomena described in this paper.

Chromosome polymorphism and sex determination in a wild population of tsetse.

SEX in the Diptera is determined by a variety of genetic mechanisms ranging from the simple condition of male or female heterogamety to complex polygenic systems1. Studies of tsetse flies have shown the males of all species examined to be heterogametic XY with a heteropycnotic Y chromosome2,3. Such cytological heterogamety is found in many dipteran species but the presence of ‘sex’ chromosomes does not necessarily mean that they are involved in sex determination4. Although there have been no studies specifically related to sex determination in Glossina, it has been postulated that the system is similar to that found in Drosophila5. I report here on a natural population of Glossina palpalis palpalis (R-D) found to contain a high incidence of aneuploids, the composition of which may be used to explain the mechanism of sex determination in the genus.

Integrating Sex Education into the K-12 Curriculum

hormones that regulate the system; (d) fertilization and early cleavage; (e) implantation; (f) the role of the placenta; (g) stages of embryo and fetal development; (h) general problems of pregnancy; (i) chromosomal sex determination; (j) multiple embryos; (k) the birth process; (1) genetic abnormalities; and (m) intrauterine medicine, such as amniocentesis, Rh incompatibility, and others. 3. Sexual topics relating to growth and development, including: (a) sexual differences in growth curves; (b) puberty and menarche; and (c) secondary sexual characteristics. 4. Venereal diseases.

Genetic Substrates for the Initial Evolution of Human Sociality. I. Sex Chromosome Mechanisms

"Hamilton (1964) has pointed Out, in a species with haplo-diploid sex determination, a female can do more to perpetuate her own genotype by looking after her sisters than her daughters" (Maynard Smith and Ridpath 1972, p. 452). Similarly, in a species without haplodiploid sex determination but with chromosomal sex determination, individuals of the homogametic sex can do more to perpetuate their own sex-linked genotype by looking after their same sex siblings than their own offspring. If sex-chromosome-based deviation from the general genetic coefficient of relationship has been operative as a factor favoring the evolution of sociality, then, in comparisons between birds and mammals, some general sex-role reversals in tendencies toward gregariousness or mutual tolerance should be evident. Among mammals females as the homogametic sex are expected to display more social cohesiveness than conspecific males, and they do. Among birds, males are expected to display more social cohesiveness than conspecific females, and they might in at least some species. Since species vary in their mode of sex determination, a wide variety of testable hypotheses can be quite parsimoniously generated from this proposal.

Sex determination and differentiation in mammals: hints from nature

There are a number of experiments that nature has carried out, in man and other animals, that have helped us considerably in achieving the present understanding of sex determination and differentiation. Some of the key experiments are concerned with: (1) The origin of the germ cells from the wall of the extraembryonic gut, to an understanding of which the W mutants in the mouse have contributed well. (2) The maintenance of the germ cells which in mammals demands not only the ‘right’ gonadal ambient but also its correct chromosomal make-up and correspondence with that of the germ cells (see below). (3) The key role of the Y chromosome in sex determination (namely gonad formation). This was established from the discovery of the sex chromosome anomalies in man (and the mouse), the XO (45, X) and XXY (47,XXY) complements. Other ‘experiments’, in man, with chromosome deletions, would suggest that the sex-determining factor(s) of the Y is on the short arm of this chromosome, now known to be that which associates at meiosis with the X chromosome. Studies, in embryos of the very frequent and very lethal 45,X condition, have uncovered the fact that an ovary develops with a single X chromosome (i.e. does not need the second X) which thus is not a sex determining chromosome, as far as we know, but that its ‘inert variant’ (the X-chromatin, or Barr-body, forming X) is essential for ovarian upkeep and function and thus for continued oögenesis. Yet other experiments (the XX male in man, the goat and the mouse, and the XO male mouse) suggest that ‘switch’ genes for testicular development may exist on the autosomes and be capable of working without a Y, i.e. they may take over its function in unison with two Xs, or (not surprisingly) better still with a single X. But this arrangement is not fully satisfactory as far as the production of competent mature germ cells is concerned.

Use of the Y chromosome in prenatal sex determination.

REPEATED observations of the cellular composition of human endocervical mucus from the earliest weeks of pregnancy, using various staining techniques, have revealed not only cells of maternal origin, but also choridnic cells which have been shed into the fairly static cervical mucous plug.

Y heterochromatin and XX males.

IN man the role of the Y chromosome in sex determination is unquestionable1,2. To explain the development of gonadal tissues with normal and abnormal sex-chromosome constitutions, the presence of male and female determining factors in the X and Y chromosomes (with positive and negative effects) has been postulated3. The regulation of sexual differentiation in early embryonic life has been attributed to the interaction between heterochromatins of the heterochromatic X and Y chromosomes4,5, and the masculinizing activity of the Y chromosome has been considered to result from a special heterochromatic effect of this chromosome on gonadal growth6. Evidence has been presented to show that in man the male-determining factors are located in the short arm of the Y chromosome7.

Gametogenese Et Determinisme Du Sexe Chez Le Nematode Mycophage Aphelenchoides Composticola

The cytological study of Aphelenchoides composticola gametogenesis shows that the diploid chromosome number is 4 A XX in females and 4 A XO in males. Hence, in this mycophagous gonochoristic nematode, the chromosomal sex determination is a Protenor type one. Irregularities in the duplication of one heteropycnotic chromosome, in some nuclei, during premeiotic stages of spermatogenesis, can explain the quantitative difference found in the adults and the fact that the females outnumber the males (tertiary sex ratio 0,7). These irregularities tend to produce a majority of spermatozoa with 3 chromosomes (2 AX) which will give only females, after amphimixis with ootids having a constant number of 2 AX chromosomes.

GENETIC ORIGIN OF SOME SEX DIFFERENCES AMONG HUMAN BEINGS

Sexual reproduction helps to ensure the survival of species by providing opportunities for new combinations of chromosomes in individuals. Organisms have evolved means to accomplish this end by establishing special sex-determining chromosomes which must contain the genes which decide the reproductive attributes of the individual. This decision sets in motion a train of events determining many characteristics related to and stemming from the reproductive sex of the individual which, taken in the aggregate, formulate much of his or her role in life as a male or female. Differences between the sexes are thus created which sometimes appear to be unrelated to reproductive functions, but which are traceable ultimately to them, and some of these differences might represent a hazard to one or other sex, due either to biological or cultural inequalities. Though there are occasional errors and imperfections of sex determination, the mechanism is on the whole a good one and even unsophisticated people are seldom unsure or imprecise in the diagnosis of sex among human beings. But establishment of the sex chromosomes in the forms they have taken in various organisms has resulted in certain consequences which, though they might be beneficial in some instances, certainly contribute to inequalities between the two sexes in ways not necessarily related to the reproductive aspects of sex. The disparity in size between the X and Y chromosomes, for example, means that the homogametic sex (female) is diploid with regard to many loci, while the heterogametic sex (males) must be always haploid. If these chromosomes contain genes which control functions apart from aspects of reproductive sex, even though these be compensated, the genes will be making contributions to aspects of maleness and femaleness which are not accommodated in the usual, practical definition of sex.

Ver�nderungen im Chromosomensatz heterolog wachsender Tumoren

Das chromosomale Geschlecht von Portio- und von Bronchialcarcinomen des Mannes wurde bestimmt. Bei 50 untersuchten Portiocarcinomen fanden sich im Durchschnitt 67,2% (Grenzwerte von 80%: +6,8% und −7.2%; vom Gesamtmaterial: +8,8% und −12,2%), bei 50 Bronchialcarcinomen von Mannern im Durchschnitt 17,38% (Grenzwerte von 80%: +6,62% und −7,38%; vom Gesamtmaterial +10,62% und −11,38%) chromatinpositive Zellen. Aus den Ergebnissen kann gefolgert werden, das die Carcinome, die uberwiegend bei einem Geschlecht auftreten oder entsprechend den anatomischen Gegebenheiten auf ein Geschlecht beschrankt sind, die cytomorphologischen Geschlechtsmerkmale des Muttergewebes bewahren.

Sexing of skins in East Africans.

THE determination of chromosomal sex by the microscopic examination of epidermal cells was first done by Moore, Graham and Barr1. Since then many other workers2–7 have confirmed the usefulness of this technique for sexing skins. All these workers, however, used only White skins the epidermal cells of which contain very little melanin pigment. In the epidermal cells of most East Africans, there are large amounts of melanin pigment which tends to obscure nuclear detail. Unless this pigment was removed prior to staining, it would make chromosomal sex determination either very difficult or impossible. It was this fact which convinced me that it would be worth while finding out whether the technique for sexing skins, as originally used by Moore et al.1, would be useful or practicable in East Africans and other dark-skinned races.

Chromosome Behavior, Inheritance and Sex Determination in Sciara

Chromosome Behavior, Inheritance and Sex Determination in Sciara

A Possible Alternative to the Hypothesis of Selective Fertilization in Sciara

Previous articleNext article No AccessShorter Articles and DiscussionA Possible Alternative to the Hypothesis of Selective Fertilization in SciaraCharles W. MetzCharles W. Metz Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 64, Number 693Jul. - Aug., 1930 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/280323 Views: 2Total views on this site Citations: 5Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Susan A. Gerbi Non-random chromosome segregation and chromosome eliminations in the fly Bradysia (Sciara), Chromosome Research 30, no.2-32-3 (Jul 2022): 273–288.https://doi.org/10.1007/s10577-022-09701-9 C. W. Metz Chromosome Behavior, Inheritance and Sex Determination in Sciara, The American Naturalist 72, no.743743 (Oct 2015): 485–520.https://doi.org/10.1086/280803Anne Marie Bois Chromosome behavior during cleavage in the eggs of Sciara coprophila (Diptera) in the relation to the problem of sex determination, Zeitschrift f�r Zellforschung und Mikroskopische Anatomie 19, no.33 (Jan 1933): 595–614.https://doi.org/10.1007/BF00393361Anne Marie Du Bois A contribution to the embryology of sciara (diptera), Journal of Morphology 54, no.11 (Dec 1932): 161–195.https://doi.org/10.1002/jmor.1050540105 C. W. Metz Unisexual Progenies and Sex Determination in Sciara, The Quarterly Review of Biology 6, no.33 (Sep 2015): 306–312.https://doi.org/10.1086/394382