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Статті в журналах з теми "Sexual chromosome":
1
Anderson, Nathan W., Carl E. Hjelmen, and Heath Blackmon. "The probability of fusions joining sex chromosomes and autosomes." Biology Letters 16, no. 11 (November 2020): 20200648. http://dx.doi.org/10.1098/rsbl.2020.0648.
Анотація:
Chromosome fusion and fission are primary mechanisms of karyotype evolution. In particular, the fusion of a sex chromosome and an autosome has been proposed as a mechanism to resolve intralocus sexual antagonism. If sexual antagonism is common throughout the genome, we should expect to see an excess of fusions that join sex chromosomes and autosomes. Here, we present a null model that provides the probability of a sex chromosome autosome fusion, assuming all chromosomes have an equal probability of being involved in a fusion. This closed-form expression is applicable to both male and female heterogametic sex chromosome systems and can accommodate unequal proportions of fusions originating in males and females. We find that over 25% of all chromosomal fusions are expected to join a sex chromosome and an autosome whenever the diploid autosome count is fewer than 16, regardless of the sex chromosome system. We also demonstrate the utility of our model by analysing two contrasting empirical datasets: one from Drosophila and one from the jumping spider genus Habronattus . We find that in the case of Habronattus , there is a significant excess of sex chromosome autosome fusions but that in Drosophila there are far fewer sex chromosome autosome fusions than would be expected under our null model.
2
Liu, Wan-Sheng. "Mammalian Sex Chromosome Structure, Gene Content, and Function in Male Fertility." Annual Review of Animal Biosciences 7, no. 1 (February 15, 2019): 103–24. http://dx.doi.org/10.1146/annurev-animal-020518-115332.
Анотація:
Mammalian sex chromosomes evolved from an ordinary pair of autosomes. The X chromosome is highly conserved, whereas the Y chromosome varies among species in size, structure, and gene content. Unlike autosomes that contain randomly mixed collections of genes, the sex chromosomes are enriched in testis-biased genes related to sexual development and reproduction, particularly in spermatogenesis and male fertility. This review focuses on how sex chromosome dosage compensation takes place and why meiotic sex chromosome inactivation occurs during spermatogenesis. Furthermore, the review also emphasizes how testis-biased genes are enriched on the sex chromosomes and their functions in male fertility. It is concluded that sex chromosomes are critical to sexual development and male fertility; however, our understanding of how sex chromosome genes direct sexual development and fertility has been hampered by the structural complexities of the sex chromosomes and by the multicopy nature of the testis gene families that also play a role in immunity, cancer development, and brain function.
3
Li, Yiyuan, Bo Zhang, and Nancy A. Moran. "The Aphid X Chromosome Is a Dangerous Place for Functionally Important Genes: Diverse Evolution of Hemipteran Genomes Based on Chromosome-Level Assemblies." Molecular Biology and Evolution 37, no. 8 (April 14, 2020): 2357–68. http://dx.doi.org/10.1093/molbev/msaa095.
Анотація:
Abstract Different evolutionary forces shape gene content and sequence evolution on autosomes versus sex chromosomes. Location on a sex chromosome can favor male-beneficial or female-beneficial mutations depending on the sex determination system and selective pressure on different sexual morphs. An X0 sex determination can lead to autosomal enrichment of male-biased genes, as observed in some hemipteran insect species. Aphids share X0 sex determination; however, models predict the opposite pattern, due to their unusual life cycles, which alternate between all-female asexual generations and a single sexual generation. Predictions include enrichment of female-biased genes on autosomes and of male-biased genes on the X, in contrast to expectations for obligately sexual species. Robust tests of these models require chromosome-level genome assemblies for aphids and related hemipterans with X0 sex determination and obligate sexual reproduction. In this study, we built the first chromosome-level assembly of a psyllid, an aphid relative with X0 sex determination and obligate sexuality, and compared it with recently resolved chromosome-level assemblies of aphid genomes. Aphid and psyllid X chromosomes differ strikingly. In aphids, female-biased genes are strongly enriched on autosomes and male-biased genes are enriched on the X. In psyllids, male-biased genes are enriched on autosomes. Furthermore, functionally important gene categories of aphids are enriched on autosomes. Aphid X-linked genes and male-biased genes are under relaxed purifying selection, but gene content and order on the X is highly conserved, possibly reflecting constraints imposed by unique chromosomal mechanisms associated with the unusual aphid life cycle.
4
Filippova, V. V. "Shereshevsky–Turner Syndrome is a natural model of primary hypogonadism in girls (a clinical case)." Public health of the Far East Peer-reviewed scientific and practical journal 94, no. 4 (December 23, 2022): 60–64. http://dx.doi.org/10.33454/1728-1261-2022-4-60-64.
Анотація:
Shereshevsky-Turner syndrome refers to chromosomal diseases associated with the pathology of sex chromosome. The syndrome is the only viable monosomy (there is only one chromosome from a couple), refers to frequent genomic disorders. At the same time, the lack of recognizable phenotypic symptoms, the gradual development of quite common manifestations (deviations of physical and sexual development) complicates the timely diagnosis of the syndrome. The lag in growth, the formation of secondary sexual characteristics is a factor requiring clarification of the cause. The time of diagnosis is the key to timely therapeutic tactics, which provides an improvement in the quality of life in caae of the pathology of sexual chromosomes, optimal socialization in modern society. The lack of diagnosis does not allow to start the necessary pathogenetic therapy
5
Coyne, Jerry A. "Genetics of sexual isolation in male hybrids of Drosophila simulans and D. mauritiana." Genetical Research 68, no. 3 (December 1996): 211–20. http://dx.doi.org/10.1017/s0016672300034182.
Анотація:
SummarySexual isolation between the sibling species D. simulans and D. mauritiana is due largely to the rejection of D. simulans males by D. mauritiana females. Genetic analysis shows that genes on the X and third chromosomes contribute to the differences between males causing sexual isolation, while the Y chromosome, second chromosome and cytoplasm have no effect. These chromosome effects differ from those observed in a previous analysis of sexual isolation in hybrid females, implying that different genes cause sexual isolation in the two sexes.
6
Yadav, Vikas, Sheng Sun, Marco A. Coelho, and Joseph Heitman. "Centromere scission drives chromosome shuffling and reproductive isolation." Proceedings of the National Academy of Sciences 117, no. 14 (March 19, 2020): 7917–28. http://dx.doi.org/10.1073/pnas.1918659117.
Анотація:
A fundamental characteristic of eukaryotic organisms is the generation of genetic variation via sexual reproduction. Conversely, significant large-scale genome structure variations could hamper sexual reproduction, causing reproductive isolation and promoting speciation. The underlying processes behind large-scale genome rearrangements are not well understood and include chromosome translocations involving centromeres. Recent genomic studies in theCryptococcusspecies complex revealed that chromosome translocations generated via centromere recombination have reshaped the genomes of different species. In this study, multiple DNA double-strand breaks (DSBs) were generated via the CRISPR/Cas9 system at centromere-specific retrotransposons in the human fungal pathogenCryptococcus neoformans. The resulting DSBs were repaired in a complex manner, leading to the formation of multiple interchromosomal rearrangements and new telomeres, similar to chromothripsis-like events. The newly generated strains harboring chromosome translocations exhibited normal vegetative growth but failed to undergo successful sexual reproduction with the parental wild-type strain. One of these strains failed to produce any spores, while another produced ∼3% viable progeny. The germinated progeny exhibited aneuploidy for multiple chromosomes and showed improved fertility with both parents. All chromosome translocation events were accompanied without any detectable change in gene sequences and thus suggest that chromosomal translocations alone may play an underappreciated role in the onset of reproductive isolation and speciation.
7
Alton, Michelle, Mau Pan Lau, Michele Villemure, and Teruko Taketo. "The behavior of the X- and Y-chromosomes in the oocyte during meiotic prophase in the B6.YTIR sex-reversed mouse ovary." REPRODUCTION 135, no. 2 (February 2008): 241–52. http://dx.doi.org/10.1530/rep-07-0383.
Анотація:
Sexual differentiation of the germ cells follows gonadal differentiation, which is determined by the presence or the absence of the Y-chromosome. Consequently, oogenesis and spermatogenesis take place in the germ cells with XX and XY sex chromosomal compositions respectively. It is unclear how sexual dimorphic regulation of meiosis is associated with the sex-chromosomal composition. In the present study, we examined the behavior of the sex chromosomes in the oocytes of the B6.YTIRsex-reversed female mouse, in comparison with XO and XX females. As the sex chromosomes fail to pair in both XY and XO oocytes during meiotic prophase, we anticipated that the pairing failure may lead to excessive oocyte loss. However, the total number of germ cells, identified by immunolabeling of germ cell nuclear antigen 1 (GCNA1), did not differ between XY and XX ovaries or XO and XX ovaries up to the day of delivery. The progression of meiotic prophase, assessed by immunolabeling of synaptonemal complex components, was also similar between the two genotypes of ovaries. These observations suggest that the failure in sex-chromosome pairing is not sufficient to cause oocyte loss. On the other hand, labeling of phosphorylated histone γH2AX, known to be associated with asynapsis and transcriptional repression, was seen over the X-chromosome but not over the Y-chromosome in the majority of XY oocytes at the pachytene stage. For comparison, γH2AX labeling was seen only in the minority of XX oocytes at the same stage. We speculate that the transcriptional activity of sex chromosomes in the XY oocyte may be incompatible with ooplasmic maturation.
8
Branco, Sara, Hélène Badouin, Ricardo C. Rodríguez de la Vega, Jérôme Gouzy, Fantin Carpentier, Gabriela Aguileta, Sophie Siguenza, et al. "Evolutionary strata on young mating-type chromosomes despite the lack of sexual antagonism." Proceedings of the National Academy of Sciences 114, no. 27 (June 19, 2017): 7067–72. http://dx.doi.org/10.1073/pnas.1701658114.
Анотація:
Sex chromosomes can display successive steps of recombination suppression known as “evolutionary strata,” which are thought to result from the successive linkage of sexually antagonistic genes to sex-determining genes. However, there is little evidence to support this explanation. Here we investigate whether evolutionary strata can evolve without sexual antagonism using fungi that display suppressed recombination extending beyond loci determining mating compatibility despite lack of male/female roles associated with their mating types. By comparing full-length chromosome assemblies from five anther-smut fungi with or without recombination suppression in their mating-type chromosomes, we inferred the ancestral gene order and derived chromosomal arrangements in this group. This approach shed light on the chromosomal fusion underlying the linkage of mating-type loci in fungi and provided evidence for multiple clearly resolved evolutionary strata over a range of ages (0.9–2.1 million years) in mating-type chromosomes. Several evolutionary strata did not include genes involved in mating-type determination. The existence of strata devoid of mating-type genes, despite the lack of sexual antagonism, calls for a unified theory of sex-related chromosome evolution, incorporating, for example, the influence of partially linked deleterious mutations and the maintenance of neutral rearrangement polymorphism due to balancing selection on sexes and mating types.
9
Shaw, G., MB Renfree, and RV Short. "Primary Genetic-Control of Sexual-Differentiation in Marsupials." Australian Journal of Zoology 37, no. 3 (1989): 443. http://dx.doi.org/10.1071/zo9890443.
Анотація:
Marsupials, like eutherians, normally require the presence of a Y chromosome for testicular formation. However some sexually dimorphic characters such as the scrotum, mammary anlagen, gubernaculum and processus vaginalis appear to be under direct genetic rather than secondary hormonal control. Scrota1 development occurs where only a single X chromosome is functional, whilst two X chromosomes are necessary for pouch formation.
10
Lardon, André, Sevdalin Georgiev, Abdelmalik Aghmir, Guenaël Le Merrer, and Ioan Negrutiu. "Sexual Dimorphism in White Campion: Complex Control of Carpel Number Is Revealed by Y Chromosome Deletions." Genetics 151, no. 3 (March 1, 1999): 1173–85. http://dx.doi.org/10.1093/genetics/151.3.1173.
Анотація:
Abstract Sexual dimorphism in the dioecious plant white campion (Silene latifolia = Melandrium album) is under the control of two main regions on the Y chromosome. One such region, encoding the gynoecium-suppressing function (GSF), is responsible for the arrest of carpel initiation in male flowers. To generate chromosomal deletions, we used pollen irradiation in male plants to produce hermaphroditic mutants (bsx mutants) in which carpel development was restored. The mutants resulted from alterations in at least two GSF chromosomal regions, one autosomal and one located on the distal half of the (p)-arm of the Y chromosome. The two mutations affected carpel development independently, each mutation showing incomplete penetrance and variegation, albeit at significantly different levels. During successive meiotic generations, a progressive increase in penetrance and a reduction in variegation levels were observed and quantified at the level of the Y-linked GSF (GSF-Y). Possible mechanisms are proposed to explain the behavior of the bsx mutations: epigenetic regulation or/and second-site mutation of modifier genes. In addition, studies on the inheritance of the hermaphroditic trait showed that, unlike wild-type Y chromosomes, deleted Y chromosomes can be transmitted through both the male and the female lines. Altogether, these findings bring experimental support, on the one hand, to the existence on the Y chromosome of genic meiotic drive function(s) and, on the other hand, to models that consider that dioecy evolved through multiple mutation events. As such, the GSF is actually a system containing more than one locus and whose primary component is located on the Y chromosome.
Дисертації з теми "Sexual chromosome":
1
Molinier, Cécile. "Transitions between reproductive systems in Daphnia." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONG003.
Анотація:
Chez les eucaryotes, les transitions entre les systèmes de reproduction sont très fréquentes. Afin d’évaluer les avantages et les coûts évolutifs des différents systèmes de reproduction, il est nécessaire de comprendre les forces sélectives sous-jacentes. Au cours des dernières décennies, les études empiriques sur l'écologie et la génétique des systèmes de reproduction se sont concentrées sur les conséquences à long terme de populations naturelles. Ma thèse a pour but de montrer comment les premières étapes de transitions entre les systèmes de reproduction sont les éléments clés pour comprendre leur évolution. Dans ce but, j'ai utilisé Daphnia spp. communément appelée « puce d'eau » comme système modèle afin d’étudier les conséquences génétiques de nouveaux systèmes de reproduction. Tout d'abord, à travers une synthèse bibliographique, j’ai testé si la vision traditionnelle de l'asexualité équivalente à clonalité (la production de descendants génétiquement identiques) est réaliste chez les animaux. Ce projet a montré que les asexués conservent de nombreuses caractéristiques de la sexualité à partir de laquelle ils ont évolué, démontrant que la clonalité stricte n'est pas prééminente. Bien que l'évolution secondaire de l'asexualité semble favoriser la reproduction clonale, les premières formes asexuées ne sont certainement pas clonales, en particulier du fait de la recombinaison. Dans un deuxième temps, j'ai effectué des croisements entre sexués et asexués chez Daphnia pulex où des lignées se reproduisant par asexualité obligatoire et produisant des "mâles rares" coexistent avec des lignées sexuées. J'ai ainsi étudié le taux de recombinaison de ces mâles asexués et j'ai pu montrer que les mâles asexués et sexués ont le même taux et le même profil de recombinaison, alors que les femelles asexuées ne recombinent pas par rapport aux femelles sexuées. Ces résultats ont montré que chez cette espèce l'évolution de la suppression de la recombinaison est spécifique aux femelles ainsi que probablement les modifications de méiose à l’origine de l’asexualité. Ces deux projets ont montré que la recombinaison n'est pas exclusive à la reproduction sexuée. Troisièmement, comme les mâles transmettent les gènes d'asexualité par le biais de ces croisements sexués-asexués (appelé asexualité contagieuse), j'ai également étudié les modes de reproduction et la valeur sélective des asexués générés en laboratoire par rapport aux lignées naturelles. Les nouveaux asexués générés sont en majorité non clonaux et ont une moins bonne valeur sélective que les lignées naturelles. Ces résultats suggèrent que les lignées asexuées évoluent relativement rapidement pour acquérir les caractéristiques des lignées asexuées observées dans la nature. Enfin, en utilisant une autre espèce, D. magna, nous avons étudié les différents niveaux d’expression de gènes entre des lignées composées exclusivement de femelles porteuses d'un proto chromosome sexuel et des lignées proches dont le sexe des individus est déterminé par l'environnement. Cette étude a montré que l'évolution des femelles dont le sexe est déterminé génétiquement et qui ne peuvent plus produire de mâles n'est pas déterminée par une mutation impliquant une perte de fonction mais plutôt par une base génétique plus complexe. Ce travail illustre l’intérêt d'utiliser des espèces présentant un polymorphisme dans les systèmes de reproduction afin d’étudier les premières étapes évolutives de transitions vers les systèmes reproductifs présents dans la natureTransitions between reproductive systems are very frequent in eucaryotes. Getting a comprehensive view of the actual evolutive advantages and costs of the different reproductive systems requires the understanding of the selective forces shaping such transitions. Over the last decades, empirical studies on the ecology and genetics of reproductive systems focused on long-term consequences and were conducted on natural populations. My PhD thesis aims at showing how early steps during transitions between reproductive systems are a key component to understand their evolution. To this end, I used the water flea; Daphnia spp. as a model system and study the genetic consequences of new reproductive systems. First, I investigated in the literature of asexual animals, whether the traditional view of asexuality as clonality (producing identical offspring) is realistic. This project showed that asexuals retain many features associated with sexuality from which they evolved so that strict clonality is not preeminent. While secondary evolution seems to favor clonality-like reproduction, the first steps of asexual evolution are certainly not clonal, particularly due to recombination. Second, I performed sex-asex crosses in a Daphnia species where obligate asexuals lineages producing “rare males” co-occur with sexuals. I studied the recombination rate of these asexual males and found that asexual males recombine as much as sexual ones, while asexual females recombine much less than sexual females. These results showed that the evolution of suppression of recombination is female-specific in this species and that meiosis modifications are also probably female-specific. The two projects showed that recombination is not exclusive to sexuals. Third, because males transmit asexuality genes via such crosses (a process called contagious asexuality), I also studied the reproductive modes and fitness of lab-generated asexuals compared to natural lineages. Interestingly, whereas natural asexuals are clonal, I found that new asexuals are in majority not clonal and less fit than natural ones. These results suggest that asexual lineages evolve relatively quickly to acquire the characteristics of the asexual lineages observed in natura. Fourth, using another Daphnia species, we investigated the gene expression levels of individuals with an incipient sex chromosome compared to closely related lineages whose sex is environmentally determined. I found that the evolution of genetically determined females that lost the ability to produce males is not determined by a “loss-of-function" mutation but rather by a more complex molecular mechanism. This work illustrates the relevance of using species with polymorphic reproductive systems to investigate the early evolutionary transitions between reproductive systems found in nature
2
Balinski, Michael A. "Differential Sexual Survival of D. Melanogaster on Copper Sulfate." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1462973269.
3
Soh, Ying Qi Shirleen. "The genomic and genetic basis of mammalian sexual reproduction : sequence of the mouse Y chromosome, and a gene regulatory program for meiotic prophase." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98632.
Анотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Mammalian sexual reproduction requires sexual determination, sexual differentiation, and the production of haploid gametes. In this thesis, I examined the genomic evolution of the mouse Y chromosome, which instructs sexual determination, and genetic regulation of a program of gene expression for meiosis, a specialized cell cycle which gives rise to haploid gametes. Chapter 2 describes the study of the mouse Y chromosome. Contrary to popular theory that Y chromosomes should be degenerate and gene poor, we find that the mouse male-specific region of the Y chromosome (MSY) is almost entirely euchromatic and contains about 700 protein-coding genes. Almost all of these genes belong to three acquired, massively amplified gene families that have no homologs on primate MSYs but do have acquired, amplified homologs on the mouse X chromosome. We propose that lineage-specific convergent acquisition and amplification of X-Y gene families is a result of sex-linked meiotic drive. Chapter 3 describes the gene regulatory program of meiotic prophase. Meiotic prophase comprises a complex chromosomal program results in the production of haploid gametes. This must be supported by a program of gene expression via which the required genes are induced. We interrogated gene expression in fetal ovaries over time and space, and in mutants of Dazl and Stra8 - key genes required for meiotic initiation. We determined that genes are regulated in three classes. Class 1 genes are expressed independently of Stra8, class 2 genes are expressed partially independently of Stra8, and Class 3 genes are dependent on Stra8 to be expressed. All genes require Dazl to be expressed. We propose that the Stra8-independent genes may represent genes required to be expressed prior to or early during meiotic initiation. Following initiation of meiosis, we found that Stra8 is required to induce down-regulation of its own expression. We propose that induction of down-regulation of the initiating signal by itself serves to ensure timely cessation of and one-time activation of the chromosomal program of meiotic prophase.
by Ying Qi Shirleen Soh.
Ph. D.
4
Morey, Céline. "Caractérisation du rôle de la région en aval du gène Xist lors de l'inactivation du chromosome X murin par mutagenèse ciblée dans les cellules ES." Paris 5, 2004. http://www.theses.fr/2004PA05N040.
Анотація:
Chez les mammifères, la compensation de dose des gènes liés à l' X entre les sexes est assurée par l' inactivation transcriptionnelle de l' un des deux chromosomes X, au hasard, chez la femelle. Ce processus dépend des fonctions de comptage et de choix et recquiert l' expression du gène Xist localisé sur le chromosome X. Ce gène produit un grand ARN non-codant qui recouvre le chromosome X inactif. La délétion de 65 kb en aval de Xist, incluant le minisatellite DXPas 34 et l' initiation d' une transcription antisens (Tsix), dans des cellules ES-cellules récapitulant l' inactivation lors de leur différenciation in vitro-induit l'altération du choix et du comptage. Par une stratégie de complémentation cre/oxP, nous avons montré que la restitution de Tsix au site de la délétion de 65 kb dans les cellules XX est insuffisante au rétablissement de l' inactivation aléatoire. . .In mammals, dosage compensation of X-linked genes is ensured by X-chromosome inactivation wherby one X chromosome in each female embryonic cell (ES) is chosen at random to become silenced. X-inactivation depends on the counting of X chromosomes and on the choice of the inactive X, It is mediated by the expression of the Xist non-coding RNA wich coats the inactive X and by the Tsix antisense transcipt, a Tsix antisense transcript, a Xist regulator. A 65 kb deletion extending 3' to Xist and including both Tsix and the DXPas34 minisatellite, disrupts choice and counting. Using a cre/loxP site-specific re-insertion strategy in XX deleted ES cells we showed that targeting back, at the 65 kb mutated locus, the Tsix antisense transcription fails to retore random X-inactivation. In contrast, normal counting can be restored in XO deleted ES cells. .
5
BIANCHI, Alessia. "Microchimerism and multiple sclerosis: a study on the impact of the sex of offspring on clinical, radiological, and paraclinical features of maternal disease. A new point of view for the sex differences in Neurological disease." Doctoral thesis, Università degli Studi di Palermo, 2023. https://hdl.handle.net/10447/580074.
Анотація:
Background. Multiple sclerosis (MS) is a chronic autoimmune disorder characterised by inflammation and neurodegeneration and representing one of the most common causes of neurologic disability among young adults. Over the last 40 years, several authors have confirmed the existence of fetal cells in maternal blood and their pregnancy-related origin, demonstrating that pregnancy may establish a long-term, low-grade chimeric state in women. The biological and clinical significance of fetal microchimeric cells (fMCs) in maternal health is largely unknown, although a role in autoimmune diseases have been hypothesised.
Aims. The overarching aim of my PhD dissertation was to investigate the role of the sex of offspring, considered an indirect marker of fMCs, in clinical, paraclinical, and radiological MS features.
Methods. During my PhD course, I conducted two retrospective studies and one prospective study on female MS patients. proceeding from literature data on the association between pregnancy and microchimerism, subjects were classified according to their pregnancy status and sex of offspring as follow: (a) subjects with history of at least a male pregnancy and supposedly carrying XY microchimeric cells (XYp), (b) subjects with history of only female pregnancy and supposedly carrying XX microchimeric cells, but not XY microchimeric cells (XXp), and (c) nulliparous subjects supposedly without microchimeric cells (NLp).
In the first project, I obtained information on pregnancy history for a population of 354 MS female patients, including 87 nulliparous subjects (NLp), 188 subjects with history of at least a male pregnancy (XYp), and 79 subjects with history of only female pregnancy (XXp). Medical records were used to collect clinical, radiological, and paraclinical data at onset, diagnosis, and last clinical follow-up for this large cohort of patients.
In the second study I selected a subgroup of 54 patients from the previous cohort, including 26 NLp, 8 XXp, and 20 XYp. I processed their magnetic resonance imaging (MRI) scan using the Lesion Segmentation Tool toolbox and FreeSurfer software to obtain quantitative data on white matter, cortical, and subcortical areas. Additional clinical, radiological, and paraclinical data at onset, diagnosis, and last clinical follow-up were also collected using medical records and telephone interview.
Finally, in the third project, I enrolled 43 patients in a prospective study. The study is still on-going and the population recruited so far includes 18 NLp, 19 XYp, and 6 XXp. All patients were classified according to their obstetric history and underwent a blood test analysis to determine the microchimeric group amplifying Y chromosome-specific sequences. Each patients underwent a baseline visit to collect clinical data, an MRI scan, and an optical coherence tomography (OCT) scan.
Results. The first study showed that, at disease onset, NLp were younger than XYp and XXp and that the same group reported a longer disease duration when attending the first visit at MS Centre. In addition, data showed that NLp had less frequently a pyramidal onset when compared to XXp. Comparing XYp and XXp patients, I observed that XXp had higher ARR, a higher disability after 3 and 5 years of disease duration, and more severe ambulation scores at EDSS at 3 years of disease duration.
In the second project, I observed that NLp had lower brain volumes in several cortical areas, as well as in some subcortical and white matter volumes. More specifically, comparing NLp and XXp, I found that the former group had larger 4th ventricle and smaller right pallidum and left enthorinal volumes. NLp also reported lower thickness in left paracentral cortex, left precuneus cortex, and right lateral occipital cortex when compared with XXp. A similar trend was observed comparing NLp and XYp: NLp group had lower thickness in left paracentral cortex, left pericalcarine cortex, and right paracentral cortex. Interestingly, at the comparison between XYp and XXp, I observed that the thickness was higher in XYp in the left cuneus cortex, left pericalcarine cortex, and left insula, while XXp had a higher thickness in the right lateral occipital cortex.
In the last project, preliminary data showed that the risk of MS onset in post-partum was higher in XYp when compared to XXp. I also found that XXp patients had higher spine lesion load at diagnosis and registered higher ARR, while XYp had more frequently brainstem involvement at onset, presented more frequently with progressive MS phenotype at last clinical follow-up, and reached lower scores at PASAT. OCT revealed that, despite having a similar age and disease duration, XXp patients had lower RNFL and GCIPL thickness when compared with XYp, although the difference was not significant. I also found similar trends in XYp and XXp when these groups were compared to NLp. However, the RNFL and GCIPL was again higher in XYp when compared to NLp, while non-significant differences were detected between NLp and XXp. Overall, my results support the hypothesis that XY and XX fMCs could differently modulate the inflammatory and degenerative processes underlying MS.
Discussion. The results reported in this thesis demonstrated that the sex of offspring could influence disease features in MS. Being most of the changes occurring during pregnancy not different in male and female pregnancies, the results obtained from two retrospective studies and the preliminary findings of the prospective study suggested that (1) fMCs could be one of the pregnancy-related factors modulating the disease onset and course, and (2) the sex chromosome of fMCs could play a role on the biological processes underlying MS.
Conclusion. The hypothesis that a small percentage of cells with an XX or XY genotype could, through the expressions of sexual chromosome genes, regulate the maternal immune system and the repair mechanisms activated in the mother is fascinating and lends a fresh perspective to the sexual differences in neurological diseases. My findings suggested that XX and XY fMCs could, although marginally and likely interacting with other factors, be involved in MS inflammation and axonal degeneration, influence the immune system activation, and induce mechanism of repair. Discovering whether the presence of fetal non-self chimeric cells, and their chromosomes, may play a role in the modulation of the nervous system and its pathology is surely one of the more interesting challenges for the future.
6
Silva, Keteryne Rodrigues da [UNESP]. "Isolamento de sequências repetitivas do genoma de espécies do gênero Ancistrus (Siluriformes: Loricariidae)." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/137992.
Анотація:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O DNA pode estar organizado no genoma em sequências de cópias únicas e em sequências que se repetem várias vezes, denominadas sequências repetitivas. Estas sequências são constituídas basicamente por repetições em tandem (satélites, minissatélites e microssatélites) ou dispersas (transposons ou retrotransposons), e parecem estar envolvidas em diversos eventos celulares importantes, como por exemplo nos processos de replicação do DNA, de recombinação, de expressão gênica e de evolução dos cromossomos, auxiliando na manutenção e propagação do material genético celular. Em nível cromossômico parecem ser responsáveis por proporções significativas das variações cariotípicas observadas em diversos grupos. O gênero Ancistrus (Siluriformes, Loricariidae) apresenta atualmente 68 espécies nominais, e uma enorme quantidade de espécies ainda não identificadas. Alguns trabalhos vêm utilizando sequências repetitivas também em análises citogenéticas e moleculares para identificação de cromossomos homólogos e marcadores cariotípicos interessantes que podem auxiliar os trabalhos de identificação de espécies. Apesar de serem amplamente estudadas em diversos organismos, há ainda muito a ser entendido sobre essas sequências e sua organização no genoma. Este trabalho teve como objetivo isolar sequências repetitivas no genoma de espécies de Ancistrus, afim de encontrar possíveis marcadores para o gênero, que pudessem contribuir para o entendimento da taxonomia deste grupo, bem como auxiliar no entendimento do processo de evolução dos cromossomos sexuais dessas espécies. Dentre as sequências isoladas está um transposon da família TC1/mariner que se mostrou presente em todos os cromossomos das espécies analisadas e dois DNAs satélites que se apresentam acumulados em regiões centroméricas de alguns cromossomos. Sendo assim, este estudo resultou em dados que poderão contribuir com o entendimento da evolução cariotípica do gênero Ancistrus bem como fornecer mais informações sobre características e evolução dos cromossomos sexuais em peixes.
DNA may be organized in the genome as single copy sequences and as sequences that are repeated several times, called repetitive sequences. These sequences are basically constituted by tandem repeats (satellites, minisatellites and microsatellites) or scattered (transposons and retrotransposons), and seem to be involved in important cellular events such as, DNA replication process, recombination, gene expression and chromosome evolution, assisting in maintenance and spread the genetic material of cells. At chromosome level, seems to be significant proportions of karyotypic variations observed in several groups. The genus Ancistrus (Siluriformes, Loricariidae) has, actually, 68 nominal species and several species not identified yet. Repetitive sequences have been used in molecular cytogenetic analysis for identification of homologous chromosomes and interesting karyotypic markers that can assist in species identification works. Despite being widely studied in several organisms, there is still much to be understood about these sequences and their organization in the genome. This study aimed to isolate repetitive sequences in the genome of Ancistrusspecies in order to find possible markers for the genus, which could contribute to the understanding of the taxonomy of this group and to the understanding of the process of evolution of sex chromosomes of these species. Among the isolated sequences, there is a family of TC1/mariner transposon that showed to be present in all the chromosomes of the analyzed species, and two satellites DNAs that have accumulated in centromeric regions. Thus, this study resulted in data that could be contribute to understanding the karyotype evolution of Ancistrus genus as well as providing more information on the characteristics and evolution of sex chromosomes in fish.
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Luthringer, Rémy. "Détermination et différenciation du sexe chez l'algue brune Ectocarpus." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066677/document.
Анотація:
Le déterminisme génétique du sexe nécessite souvent l’évolution d’une région non-recombinante (NR) formant ainsi paire de chromosomes sexuels. Bien que la reproduction sexuée ait une origine commune à tous les eucaryotes, l’évolution des chromosomes sexuels s’est quant à elle effectuée de manière répétée et indépendante. Les chromosomes du sexe ont été particulièrement étudiés dans les systèmes diploïdes (chromosomes sexuels XY et ZW) des plantes et animaux. Le récent séquençage du génome d’Ectocarpus, modèle d’étude des algues brunes, donne non seulement une chance unique d’analyser les chromosomes sexuels dans un groupe phylogénétiquement distant des opisthocontes et de la lignée verte ; mais il donne aussi l’opportunité d’examiner un système haploïde de chromosomes sexuels (système UV). Chez Ectocarpus l’expression du sexe a lieu pendant la phase haploïde du cycle de vie, avec les chromosomes U et V, respectivement spécifiques aux femelles et aux mâles. L’analyse des chromosomes sexuels chez Ectocarpus a montré que la taille de la région NR est restée modeste pour un système vieux de plus de 70 millions d’années. Une analyse des dimorphismes sexuels a été effectuée ainsi que l’étude comparative des transcriptomes mâle et femelle d’Ectocarpus. Le développement parthénogénétique est, dans certaines populations d’Ectocarpus, un dimorphisme sexuel. Le lien génétique entre parthénogenèse et sexe a été analysé et suggère qu’un locus contrôlant la parthénogenèse est localisé au niveau de la partie recombinante du chromosome sexuel d’Ectocarpus. De plus, une analyse de fitness indique que le locus de la parthénogenèse est soumis à une sélection antagoniste entre les deux sexesGenetic sex determination is usually controlled by sex chromosomes carrying a non-recombining sex-determining region (SDR). Despite the common origin of sex (meiosis) in Eukaryotes, the evolution of sex chromosomes has evolved repeatedly and independently. Our knowledge in sex chromosomes comes mainly from the analysis of diploid systems (XY and ZW sex chromosomes) in animals and land plants. However the recent genome sequencing of the brown alga Ectocarpus, not only opens up the possibility of studying sex chromosomes in a phylogenetic distant group but also of analysing a haploid sex chromosome system (UV sex chromosomes). Indeed in Ectocarpus sex is expressed during the haploid phase of the life cycle, where U and V sex chromosomes are restricted to female and male, respectively. The Ectocarpus sex chromosomes have some unusual evolutionary features such as the size of the non-recombining region, which is surprisingly small for a 70 million year old system. Also the evolutionary aspect of sexual dimorphism was studied by analyzing male and female transcriptomes and by identifying several subtle sexual dimorphic traits. Parthenogenetic capacity is a sexual dimorphic trait in some populations of Ectocarpus. The genetic link between parthenogenesis and sex was analysed and a locus that controls parthenogenetic was located to the Ectocarpus sex chromosome, in the recombining pseudoautosomal region. Fitness analysis strongly suggested that the parthenogenetic locus is a sexual antagonistic locus
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Borge, Thomas. "Genetics and the Origin of Two Flycatcher Species." Doctoral thesis, Uppsala University, Evolutionary Biology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3919.
Анотація:
In this thesis, different genetic tools are used to investigate pre- and postzygotic barriers to gene exchange and their role in speciation in the pied flycatcher (Ficedula hypoleuca) and the collared flycatcher (F. albicollis). This species complex consists of four genetically distinct clades that apparently diverged in allopatry (I). Sequencing of introns from autosomal and Z-linked genes from the two species reveals signs of selection on the Z-chromosome. Sexual selection acting on Z-linked genes might explain this pattern (II). By using large-scale genotyping of single nucleotide polymorphisms (SNPs), introgression is observed at autosomal- but not Z-linked loci, mostly from the pied- to the collared flycatcher. Male plumage characters and genes involved in hybrid fitness are largely mapped to the Z-chromosome (III). By studying mate choice of female hybrids I show that there is a link between female preferences and the Z chromosome (IV). The rate of introgression in island versus clinal hybrid zones is consistent with regional differences in hybrid fertility. Asymmetric gene flow from allopatry on the islands may oppose reinforcement, leading to introgression and a partial breakdown of postzygotic isolation. Adaptive introgression may explain the high rate of introgression observed at one of the genetic markers (V). For late breeding female collared flycatchers it appears to be adaptive to use pied flycatchers as social fathers but conspecific males as genetic fathers. Additionally, females in mixed species pairs may reduce hybridization costs by producing an excess of male hybrid offspring that are more fertile than females (VI).
In conclusion, the Z-chromosome appears to play a major role in flycatcher speciation. Sexual selection and reinforcement are important mechanisms in the divergence of these birds. However, gene flow from allopatry, introgression of adaptive genes and adaptive hetrospecific pairing by late breeding collared flycatcher females may work in the opposite direction.
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Ruiz, Karine Pequeno Nakao. "Análise molecular de amostras negativas para o antígeno específico da próstata (PSA) coletadas de vítimas de crimes sexuais." Universidade Federal da Paraíba, 2017. http://tede.biblioteca.ufpb.br:8080/handle/tede/9469.
Анотація:
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The finding of sperm through the screening tests on samples collected from rape victims confirms the occurrence of the sexual act, but its absence usually closes biological research in the crime in question, leaving a gap about the authorship of the crime, as well as about the criminal typification. The present work aimed to analyze the need of implementation in forensic routine of Genetics Laboratories of molecular analysis of negative samples to the prostate-specific antigen (PSA) collected from sex crimes victims. Vaginal swabs were selected and proceedings collected from 200 women who have been victims of those crimes in Paraíba from January 2015 to January 2016. Such materials had been sorted and presented negative result for PSA. Proceeded to the sample quantification by Real-time PCR using the Plexor® HY kit and there was a far greater concentration of autosomal DNA in relation to the male DNA. With the use of thermal cyclers GeneAmp® PCR System 9700, 200 DNA samples extracted from the sperm fraction (SF) were amplified for Y-STR with the use of PowerPlex® Y23 Systems and AmpFlSTR® Yfiler PCR Amplification kits. Such products have been subjected to capillary electrophoresis in genetic sequencer ABI PRISM™ 3500 Genetic Analyzer and the results analyzed by GeneMapper® ID software v 3.2. The fractions analyzed, only two full profiles amplification (1%), 24 (12%) partials, while the 174 remaining samples (87%) did not present any amplification. Screening with PSA testing negative served, statistically, how to determine guiding absence of sperm in swabs of vaginal origin and anally for victims of sex crimes. However, in this study were analyzed samples from rape victims. Due to the large social call caused by this type of crime, any nonzero statistic must be acceptable to a presumptive test. The results obtained have awakened to the need to study a new way of sorting this material, as well as the repetition of some analytical steps in order to get a genetic profile informative for illicit criminal resolution.
A constatação de espermatozoides, através dos testes de triagem, em amostras coletadas de vítimas de estupro confirma a ocorrência do ato sexual, todavia a sua ausência geralmente encerra a investigação biológica no crime em questão, ficando uma lacuna quanto à autoria do delito, bem como quanto à tipificação penal. O presente trabalho objetivou analisar a necessidade de implantação na rotina dos laboratórios de genética forense da análise molecular de amostras negativas para o antígeno específico da próstata (PSA) coletadas de vítimas de crimes sexuais. Foram selecionadas swabs vaginais e anais coletados de 200 mulheres que foram vítimas desses crimes na Paraíba entre os meses de janeiro de 2015 e janeiro de 2016. Tais materiais haviam sido triados e apresentaram resultado negativo para PSA. Procedeu-se à quantificação amostral por PCR em tempo real, com uso do kit Plexor® HY e observou-se uma concentração bem maior de DNA autossômico com relação ao DNA masculino. Com uso de termocicladores GeneAmp® PCR System 9700, 200 amostras de DNA extraído das frações espermáticas (FE) foram amplificadas para Y-STR com o emprego dos sistemas PowerPlex® Y23 System e AmpFlSTR® Yfiler® PCR Amplification. Tais produtos foram submetidos à eletroforese capilar em seqüenciador genético ABI PRISM 3500™ Genetic Analyzer e os resultados analisados pelo software GeneMapper® ID v3.2. Das frações analisadas, constatou-se amplificação de apenas dois perfis completos (1%), 24 parciais (12%), enquanto as 174 amostras restantes (87%) não apresentaram amplificação alguma. O teste de triagem com PSA negativo serviu, estatisticamente, como norteador para se determinar a ausência de esperma em swabs de origem vaginal e anal das vítimas de crimes sexuais. Contudo, no presente trabalho foram analisadas amostras provenientes de vítimas de estupro. Devido ao grande apelo social provocado por esse tipo de crime, nenhuma estatística diferente de zero deve ser aceitável para um teste presuntivo. Os resultados obtidos despertaram para a necessidade de estudar uma nova forma de triagem desse material, bem como pela repetição de alguns passos analíticos no intuito de se obter um perfil genético informativo para resolução do ilícito penal.
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Guedes, Alexis Dourado [UNIFESP]. "Determinação do fenótipo sexual em uma criança com Mosaicismo 45,X/46,X,Idic(Yp): importância da proporção relativa da linhagem 45,X no tecido gonadal." Universidade Federal de São Paulo (UNIFESP), 2006. http://repositorio.unifesp.br/handle/11600/9326.
Анотація:
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Previous issue date: 2006-12-31We report here on a girl who, despite her 45,X/46,X,der(Y) karyotype, showed no signs of virilization or physical signs of the Ullrich-Turner syndrome [UTS], except for a reduced growth rate. After prophylactic gonadectomy due to the risk of developing gonadoblastoma, the gonads and peripheral blood samples were analyzed by fluorescence in situ hybridization [FISH] and polymerase chain reaction [PCR] to detect Y-specific sequences. These analyses allowed us to characterize the Yderived chromosome as being an isodicentric Yp chromosome [idic(Yp)] and showed a pronounced difference in the distribution of the 45,X/46,X,idic(Yp) mosaicism between the two analyzed tissues. It was shown that, although in peripheral blood almost all cells (97.5%) belonged to the idic(Yp) line with a duplicated SRY gene, this did not determine any degree of male sexual differentiation in the patient, as in the gonads the predominant cell line was 45,X (60%).
TEDE
BV UNIFESP: Teses e dissertações
Книги з теми "Sexual chromosome":
1
Pinsky, Leonard. Genetic disorders of human sexual development. New York: Oxford University Press, 1999.
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Beit-Aharon, Claudette. Standing tall with Turner Syndrome: Essays by women with Turner Syndrome. 2nd ed. Newton, MA: Nanomir Press, 2013.
3
John, Money. Sex errors of the body and related syndromes: A guide to counseling children, adolescents, and their families. 2nd ed. Baltimore: P.H. Brookes Pub. Co., 1994.
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John, Money. The Adam principle: Genes, genitals, hormones & gender : selected readings in sexology. Buffalo, N.Y: Prometheus Books, 1993.
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John, Money. Vandalized lovemaps: Paraphilic outcome of seven cases in pediatric sexology. Buffalo, N.J: Prometheus Books, 1989.
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John, Money. Vandalized lovemaps: Paraphilic outcome of seven cases in pediatric sexology. Buffalo, N.J: Prometheus Books, 1989.
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Hamer, Dean H. The science of desire: The search for the gay gene and the biology of behavior. New York: Simon & Schuster, 1994.
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Hamer, Dean H. The science of desire: The search for the gay gene and the biology of behavior. New York: Simon & Schuster, 1995.
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Echeverría, Isabel Delgado. El descubrimiento de los cromosomas sexuales: Un hito en la historia de la biología. Madrid: Consejo Superior de Investigaciones Científicas, 2007.
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Albany Birth Defects Symposium (20th 1989). Fragile X--cancer cytogenetics: Proceedings of the 1989 Albany Birth Defects Symposium XX, held in Albany, New York, October 16-17, 1989. Edited by Willey Ann M and Murphy Patricia D. New York: Wiley-Liss, 1991.
Частини книг з теми "Sexual chromosome":
1
Vignozzi, Linda, Annamaria Morelli, and Mario Maggi. "Sexual Aspects of Klinefelter's Syndrome and other Sex-Chromosome Disorders." In Hormonal Therapy for Male Sexual Dysfunction, 111–17. Oxford, UK: Wiley-Blackwell, 2011. http://dx.doi.org/10.1002/9781119963820.ch9.
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Hanson, Erin K., and Jack Ballantyne. "Enhanced DNA Profiling of the Semen Donor in Late Reported Sexual Assaults: Use of Y-Chromosome-Targeted Pre-amplification and Next Generation Y-STR Amplification Systems." In Methods in Molecular Biology, 185–200. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3597-0_15.
3
Goetsch, Allison L., Dana Kimelman, and Teresa K. Woodruff. "Disorders of the Sex Chromosomes and Sexual Development." In Fertility Preservation and Restoration for Patients with Complex Medical Conditions, 19–37. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-52316-3_3.
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Bakker, Julie. "The Sexual Differentiation of the Human Brain: Role of Sex Hormones Versus Sex Chromosomes." In Neuroendocrine Regulation of Behavior, 45–67. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/7854_2018_70.
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Arnold, Arthur P., Xuqi Chen, and Yuichiro Itoh. "What a Difference an X or Y Makes: Sex Chromosomes, Gene Dose, and Epigenetics in Sexual Differentiation." In Sex and Gender Differences in Pharmacology, 67–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30726-3_4.
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Mcphaul, Michael J., and Richard J. Auchus. "Sexual Differentiation." In Textbook of Endocrine Physiology. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199744121.003.0010.
Анотація:
Sexual differentiation is a sequential process that begins at fertilization with the establishment of chromosomal sex, continues with the determination of gonadal sex, and culminates in the development of secondary sexual characteristics that comprise the male and female phenotypes. This basic paradigm was formulated by Alfred Jost to explain the results of castration experiments in fetal rabbits. If the gonads (ovaries or testes) were removed before sexual differentiation, female sexual differentiation inevitably ensued. The male pathway could be partly restored by testosterone implants, suggesting that hormones produced by the testes mediate male sexual development. Thus, the concept arose that the testes induce a male pattern of differentiation on an embryo that otherwise would follow the female pathway. Cytogenetic studies shortly thereafter showed that the critical genetic determinant of sex is the presence or absence of the Y chromosome, leading to the proposal that the Y chromosome directs the gonad to differentiate into a testis, which then produces hormone(s) that cause male sexual differentiation. The chromosomal sex of the embryo generally corresponds to its phenotypic sex. Occasionally, however, the process of sexual differentiation goes awry, resulting in individuals with disorders of sexual differentiation (DSD). Clinically recognized disorders of sexual development occur at many levels, ranging from relatively common disorders in the terminal steps of male differentiation (e.g., testicular descent, growth of the penis) to more fundamental abnormalities that lead to varying degrees of ambiguity of phenotypic sex. Although most of these abnormalities impair reproduction, they usually are not life threatening. Thus, humans and experimental animals with naturally occurring defects in sexual differentiation survive to reach the attention of physicians and scientists. This chapter reviews the sequence of events in normal sexual development and describes disorders of this process — many of which result from single-gene mutations — that have provided valuable insights into the mechanisms of sexual differentiation. Normally, human somatic cells have 22 pairs of autosomes and 1 pair of sex chromosomes.
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Ahmed, S. Faisal, and Angela K. Lucas-Herald. "Normal and abnormal sexual differentiation." In Oxford Textbook of Medicine, edited by Mark Gurnell, 2435–48. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0257.
Анотація:
Human sex development follows an orderly sequence of embryological events coordinated by a cascade of gene expression and hormone production in a time- and concentration-dependent manner. Underpinning the entire process of fetal sex development is the simple mantra: sex chromosomes (XX or XY) dictate the gonadotype (ovary or testis), which then dictates the somatotype (female or male phenotype). The constitutive sex in fetal development is female. Disorders of sex development (DSD) can be classified into three broad categories based on the knowledge of the karyotype: sex chromosome abnormality (e.g. X/XY, mixed gonadal dysgenesis); XX DSD (e.g. congenital adrenal hyperplasia); XY DSD (e.g. partial androgen insensitivity syndrome).
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"Cell Division." In Examining the Causal Relationship Between Genes, Epigenetics, and Human Health, 93–114. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8066-9.ch004.
Анотація:
Cells divide for three main reasons: growth and development, replace worn-out or injured cells, and reproduction of offspring. Cell division is part of the cell cycle divided into five distinct phases. The diploid state of the cell is the normal chromosomal number in species. During sexual reproduction, the cell's chromosome number is reduced to a haploid state to ensure constancy in chromosome number and thus continuation of the species. The process of cell division is controlled by regulatory proteins. Mitosis occurs in all body cells and is divided into four phases. Meiosis, which occurs in only the germ cells involved in reproduction, divides the chromosomes in two rounds termed meiosis I and meiosis II (reduction division). The human lifecycle starts with gametogenesis, the process that forms gametes which then combine to form a zygote. The zygote quickly becomes an embryo and develops rapidly into a foetus. This chapter explores cell division.
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Reinhold, Klaus. "Preferential Sex Linkage of Sexually Selected Genes: Evidence and a New Explanation." In The Speciation of Modern Homo Sapiens. British Academy, 2004. http://dx.doi.org/10.5871/bacad/9780197263112.003.0014.
Анотація:
This chapter discusses evidence and theory on sex chromosomal linkage of sexually selected traits that may be the key to a functional separation of sexual and natural selection. It reviews the evidence showing that the X chromosome has a disproportional share concerning the inheritance of sexually selected traits in animals with heterogametic males, and suggests a new explanation that relates this X bias with female choice of heterozygotic males. With numeric simulations, it shows that female choice of heterozygotic males is usually disadvantageous. Because this disadvantage cannot occur when females prefer X-linked male traits, preferential X linkage of sexually selected traits can be expected. As an alternative to fluctuating selection on sex-limited traits, the disadvantage of heterozygotic choice may thus explain the X bias observed for sexually selected traits.
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Zhang, Yingsheng, Dan Theodorescu, and Xue Li. "Gender Disparities in Bladder Cancer." In Bladder Cancer [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98225.
Анотація:
Biological sex is an independent risk factor of cancer. Men are three to five times more likely than women to develop bladder cancer even when known risk factors are taken into consideration. Development of sex in mammals is often viewed as a two-step process. The first step is sex determination, of which the XX and XY sex chromosome complements trigger gonad differentiation to form the ovary and testis, respectively. After that, sex hormones secreted by gonads initiate sexually dimorphic differentiation of nongonadal tissues. However, this model has been challenged by recent findings revealing an independent contribution of sex chromosomes to sexual dimorphism. In this chapter, we discuss how the sex chromosomes and sex hormones together cause gender disparities in bladder cancer. We propose a concept of epigenetic sex – epigenetic differences between males and females – and suggest that the sex epigenome is a previously unknown biasing factor contributing to gender disparities in bladder cancer.
Тези доповідей конференцій з теми "Sexual chromosome":
1
Kutch, Ian C. "Does the Y-chromosome facilitate sexual dimorphic evolution in insects or constrain autosomal evolution?" In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.114943.
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Wolffs, Petra, Christian Hoebe, Jos Herbergs, Mayk Lucchesi, Sylvia Bruisten, Hannelore Götz, Mark Van Berkel, Henry De Vries, and Nicole Dukers-Muijrers. "P241 Detection of Y-chromosomal DNA correlates with last unsafe sexual exposure." In Abstracts for the STI & HIV World Congress (Joint Meeting of the 23rd ISSTDR and 20th IUSTI), July 14–17, 2019, Vancouver, Canada. BMJ Publishing Group Ltd, 2019. http://dx.doi.org/10.1136/sextrans-2019-sti.375.
Звіти організацій з теми "Sexual chromosome":
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Pawlowski, Wojtek P., and Avraham A. Levy. What shapes the crossover landscape in maize and wheat and how can we modify it. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600025.bard.
Анотація:
Meiotic recombination is a process in which homologous chromosomes engage in the exchange of DNA segments, creating gametes with new genetic makeup and progeny with new traits. The genetic diversity generated in this way is the main engine of crop improvement in sexually reproducing plants. Understanding regulation of this process, particularly the regulation of the rate and location of recombination events, and devising ways of modifying them, was the major motivation of this project. The project was carried out in maize and wheat, two leading crops, in which any advance in the breeder’s toolbox can have a huge impact on food production. Preliminary work done in the USA and Israeli labs had established a strong basis to address these questions. The USA lab pioneered the ability to map sites where recombination is initiated via the induction of double-strand breaks in chromosomal DNA. It has a long experience in cytological analysis of meiosis. The Israeli lab has expertise in high resolution mapping of crossover sites and has done pioneering work on the importance of epigenetic modifications for crossover distribution. It has identified genes that limit the rates of recombination. Our working hypothesis was that an integrative analysis of double-strand breaks, crossovers, and epigenetic data will increase our understanding of how meiotic recombination is regulated and will enhance our ability to manipulate it. The specific objectives of the project were: To analyze the connection between double-strand breaks, crossover, and epigenetic marks in maize and wheat. Protocols developed for double-strand breaks mapping in maize were applied to wheat. A detailed analysis of existing and new data in maize was conducted to map crossovers at high resolution and search for DNA sequence motifs underlying crossover hotspots. Epigenetic modifications along maize chromosomes were analyzed as well. Finally, a computational analysis tested various hypotheses on the importance of chromatin structure and specific epigenetic modifications in determining the locations of double-strand breaks and crossovers along chromosomes. Transient knockdowns of meiotic genes that suppress homologous recombination were carried out in wheat using Virus-Induced Gene Silencing. The target genes were orthologs of FANCM, DDM1, MET1, RECQ4, and XRCC2.