scholarly journals The Human Y Chromosome: The Biological Role of a “Functional Wasteland”

2001 ◽  
Vol 1 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Lluís Quintana-Murci ◽  
Marc Fellous
Keyword(s):  
Y Chromosome ◽  
Male Fertility ◽  
Its Sequence ◽  
Distinguishing Characteristic ◽  
Biological Functions ◽  
Sry Gene ◽  
Male Phenotype ◽  
Mammalian Embryos ◽  
Human Y Chromosome

“Functional wasteland,” “Nonrecombining desert” and “Gene-poor chromosome” are only some examples of the different definitions given to the Y chromosome in the last decade. In comparison to the other chromosomes, the Y is poor in genes, being more than 50% of its sequence composed of repeated elements. Moreover, the Y genes are in continuous decay probably due to the lack of recombination of this chromosome. But the human Y chromosome, at the same time, plays a central role in human biology. The presence or absence of this chromosome determines gonadal sex. Thus, mammalian embryos with a Y chromosome develop testes, while those without it develop ovaries (Polani [38]). What is responsible for the male phenotype is the testis-determining SRY gene (Sinclair [52]) which remains the most distinguishing characteristic of this chromosome. In addition to SRY, the presence of other genes with important functions has been reported, including a region associated to Turner estigmata, a gene related to the development of gonadoblastoma and, most important, genes related to germ cell development and maintenance and then, related with male fertility (Lahn and Page [31]). This paper reviews the structure and the biological functions of this peculiar chromosome.

scholarly journals Rich polymorphic variants of alpha satellite 34mer higher order repeats in hg38 assembly of human chromosome Y

2019 ◽  
Author(s):  
Ines Vlahović ◽  
Matko Glunčić ◽  
Vladimir Paar
Keyword(s):  
Cell Division ◽  
Y Chromosome ◽  
Tandem Repeats ◽  
Genomic Sequence ◽  
Higher Order ◽  
Alpha Satellite ◽  
Satellite Dnas ◽  
Polymorphic Variants ◽  
Human Y Chromosome

AbstractA challenging problem in human population genetics is related to the unique role of human Y chromosome, with properties that distinguish humans from other species. Centromeres in primate genomes are constituted of tandem repeats of ∼ 171 bp alpha satellite monomers, commonly organized into higher order repats (HORs). Because of gaps in DNA sequencing, HOR regions as genomic “black holes” have been understudied in spite of crucial importance. Only recently the sequencing of more complete satellite DNAs becomes accessible. In human Y chromosome the largest alpha satellite higher order repeat unit 34/36mer was found, but its polymorphic variants were not investigated. Here, we study the human Y chromosome centromeric genomic sequence from hg38 assembly using our novel ALPHAsub algorithm for simple identification of alpha satellite arrays and robust GRM algorithm for HOR identification in repeat sequences. We determine the monomer alignment scheme for alpha satellite HOR array based on canonical 34mer HOR, discovering a wealth of novel polymorphic variants which include the HOR-type monomer duplications, monomer deletions/insertions or rearrangements and non-HOR insertions.Author SummaryThe centromere is important for segregation of chromosomes during cell division in eukaryotes. Its destabilization results in chromosomal missegregation, aneuploidy, hallmarks of cancers and birth defects. In primate genomes centromeres contain tandem repeats of ∼ 171 bp alpha satellite DNA, commonly organized into higher order repeats (HORs). In this work, we used our bioinformatics algorithms to study the human Y chromosome centromeric genomic sequence and we discover a wealth of novel polymorphic variants which include the HOR-type monomer duplications, monomer deletions/insertions or rearrangements and non-HOR insertions. These results could help to understand the role of alpha satellites and alpha HOR structures in centromeric organization and function, in particular their role in creating a functional kinetochore that is crucial for chromosome segregation during cell division.

Hypothesis: a Y-chromosomal gene causes gonadoblastoma in dysgenetic gonads

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 151-155 ◽  
Author(s):  
David C. Page
Keyword(s):  
Y Chromosome ◽  
Dna Hybridization ◽  
Physiological Function ◽  
Hybridization Analysis ◽  
Chromosomal Gene ◽  
Normal Males ◽  
Part Model ◽  
Human Y Chromosome

The role of the human Y chromosome in the etiology of gonadoblastoma, a gonadal neoplasm, is considered and a two-part model is presented. According to this hypothesis: (1) There is a gene on the Y chromosome that strongly predisposes dysgenetic gonads to develop gonadoblastomas (Page, 1986) and (2) this postulated GBY gene (GonadoBlastoma locus on Y chromosome) has some physiological function in normal males. GBY may, for example, function in or prior to spermatogenesis in normal testes. Y-DNA hybridization analysis of individuals with gonadoblastoma and partial deletions of the Y chromosome should be of use in testing this proposal. To date, such studies suggest that GBY maps to the region that includes deletion intervals 4B to 7, i.e. it is located near the centromere or on the long arm of the Y chromosome.

scholarly journals Genetic Dissection of the AZF Regions of the Human Y Chromosome: Thriller or Filler for Male (In)fertility?

2010 ◽  
Vol 2010 ◽  
pp. 1-18 ◽  
Author(s):  
Paulo Navarro-Costa ◽  
Carlos E. Plancha ◽  
João Gonçalves
Keyword(s):  
Y Chromosome ◽  
Male Fertility ◽  
Molecular Mechanisms ◽  
Gene Families ◽  
Comprehensive Analysis ◽  
Gene Content ◽  
Genetic Dissection ◽  
Azoospermia Factor ◽  
Or Gene ◽  
Human Y Chromosome

The azoospermia factor (AZF) regions consist of three genetic domains in the long arm of the human Y chromosome referred to as AZFa, AZFb and AZFc. These are of importance for male fertility since they are home to genes required for spermatogenesis. In this paper a comprehensive analysis of AZF structure and gene content will be undertaken. Particular care will be given to the molecular mechanisms underlying the spermatogenic impairment phenotypes associated to AZF deletions. Analysis of the 14 different AZF genes or gene families argues for the existence of functional asymmetries between the determinants; while some are prominent players in spermatogenesis, others seem to modulate more subtly the program. In this regard, evidence supporting the notion thatDDX3Y,KDM5D,RBMY1A1,DAZ, andCDYrepresent key AZF spermatogenic determinants will be discussed.

scholarly journals New Genes in the Drosophila Y Chromosome: Lessons from D. willistoni

Genes ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1815
Author(s):  
João Ricchio ◽  
Fabiana Uno ◽  
A. Bernardo Carvalho
Keyword(s):  
Y Chromosome ◽  
Strong Evidence ◽  
Male Fertility ◽  
Gene Loss ◽  
Segmental Duplications ◽  
Duplicated Genes ◽  
New Genes ◽  
Y Chromosomes ◽  
Autosomal Copy

Y chromosomes play important roles in sex determination and male fertility. In several groups (e.g., mammals) there is strong evidence that they evolved through gene loss from a common X-Y ancestor, but in Drosophila the acquisition of new genes plays a major role. This conclusion came mostly from studies in two species. Here we report the identification of the 22 Y-linked genes in D. willistoni. They all fit the previously observed pattern of autosomal or X-linked testis-specific genes that duplicated to the Y. The ratio of gene gains to gene losses is ~25 in D. willistoni, confirming the prominent role of gene gains in the evolution of Drosophila Y chromosomes. We also found four large segmental duplications (ranging from 62 kb to 303 kb) from autosomal regions to the Y, containing ~58 genes. All but four of these duplicated genes became pseudogenes in the Y or disappeared. In the GK20609 gene the Y-linked copy remained functional, whereas its original autosomal copy degenerated, demonstrating how autosomal genes are transferred to the Y chromosome. Since the segmental duplication that carried GK20609 contained six other testis-specific genes, it seems that chance plays a significant role in the acquisition of new genes by the Drosophila Y chromosome.

The role of the mammalian Y chromosome in spermatogenesis

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 133-141
Author(s):  
Paul S. Burgoyne
Keyword(s):  
Y Chromosome ◽  
Germ Cells ◽  
Germ Line ◽  
Fetal Life ◽  
Chromosomal Gene ◽  
Male Germ Line ◽  
Germ Cell Differentiation ◽  
Sperm Abnormalities ◽  
Male Phenotype

All aspects of the mammalian male phenotype are due either directly or indirectly to Y-chromosome activity. This review summarizes what is known of the role of the Y in male germ cell differentiation in the mouse. The initial diversion of germ cells to the male pathway in fetal life (that is the formation of amitotic T1-prospermatogonia rather than meiotic oocytes) is an indirect effect of the Y: the Y-chromosomal testis determining gene (Tdy) acts to create a testis and the testicular environment causes the germ cells to follow the male pathway. XX and XO germ cells can therefore form T1-prospermatogonia, but the extra X of XX prospermatogonia in some way causes their death perinatally. The first direct effect of the Y in the germ line occurs at the initiation of the spermatogenic cycles (approx. 1 week after birth) when a Y-chromosomal gene (Spy) is needed for normal spermatogonial survival and progression to meiosis. Spy is present in the Y-derived Sxr fragment so XOSxr germ cells enter meiosis normally. An Sxr derivative, Sxr′, which has lost the capacity to produce H-Y antigen, has also lost the Spy function, raising the possibility that H-Y antigen is the mediator of Spy activity. The Y is next required in the male germ line during meiotic prophase, when it provides a pairing partner for the X chromosome. If the X (or, indeed, the Y when present) remains unpaired, there are severe spermatogenic losses and the second meiotic division is frequently omitted, leading to the formation of diploid spermatids. Spermatogenesis in XOSxr males is affected in this way and the few sperm produced are morphologically abnormal. These sperm abnormalities could also be a consequence of the X univalence, but there is some evidence suggesting that there is another gene on the Y, lacking in Sxr, which is involved in sperm morphogenesis.

scholarly journals The Role of Y Chromosome Genes in Male Fertility in Drosophila melanogaster

Genetics ◽  
2020 ◽  
Vol 215 (3) ◽  
pp. 623-633 ◽  
Author(s):  
Jiaying Zhang ◽  
Junjie Luo ◽  
Jieyan Chen ◽  
Junbiao Dai ◽  
Craig Montell
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Male Fertility ◽  
Specific Protein ◽  
Dna Repeats ◽  
Gene Sequences ◽  
Protein Coding ◽  
Fertility Factor ◽  
Link Type

The Y chromosome of Drosophila melanogaster is pivotal for male fertility. Yet, only 16 protein-coding genes reside on this chromosome. The Y chromosome is comprised primarily of heterochromatic sequences, including DNA repeats and satellite DNA, and most of the Y chromosome is still missing from the genome sequence. Furthermore, the functions of the majority of genes on the Y chromosome remain elusive. Through multiple genetic strategies, six distinct segments on the Y chromosome have been identified as “male fertility factors,” and candidate gene sequences corresponding to each of these loci have been ascribed. In one case, kl-3, a specific protein coding sequence for a fertility factor has been confirmed molecularly. Here, we employed CRISPR/Cas9 to generate mutations, and RNAi, to interrogate the requirements of protein coding sequences on the Y chromosome for male fertility. We show that CRISPR/Cas9-mediated editing of kl-2 and kl-5 causes male sterility, supporting the model that these gene sequences correspond to the cognate fertility factors. We show that another gene, CCY, also functions in male fertility and may be the ks-2 fertility factor. We demonstrate that editing of kl-2, kl-3, and kl-5, and RNAi knockdown of CCY, disrupts nuclear elongation, and leads to defects in sperm individualization, including impairments in the individualization complex (IC) and synchronization. However, CRISPR/Cas9 mediated knockout of some genes on the Y chromosome, such as FDY, Ppr-Y, and Pp1-Y2 do not cause sterility, indicating that not all Y chromosome genes are essential for male fertility.

scholarly journals Selenium and Dogs: A Systematic Review

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 418
Author(s):  
Viola Zentrichová ◽  
Alena Pechová ◽  
Simona Kovaříková
Keyword(s):  
Male Fertility ◽  
Clinical Signs ◽  
Complex Data ◽  
Selenium Status ◽  
Dog Food ◽  
Balanced Diet ◽  
Naturally Occurring ◽  
Correct Function ◽  
Indirect Assay

The intent of this review is to summarize the knowledge about selenium and its function in a dog’s body. For this purpose, systematic literature search was conducted. For mammals, including dogs, a balanced diet and sufficient intake of selenium are important for correct function of metabolism. As for selenium poisoning, there are no naturally occurring cases known. Nowadays, we do not encounter clinical signs of its deficiency either, but it can be subclinical. For now, the most reliable method of assessing selenium status of a dog is measuring serum or plasma levels. Levels in full blood can be measured too, but there are no reference values. The use of glutathione peroxidase as an indirect assay is questionable in canines. Commercial dog food manufactures follow recommendations for minimal and maximal selenium levels and so dogs fed commercial diets should have balanced intake of selenium. For dogs fed home-made diets, complex data are missing. However, subclinical deficiency seems to affect, for example, male fertility or recovery from parasitical diseases. Very interesting is the role of selenium in prevention and treatment of cancer.

scholarly journals Transcription of gypsy Elements in a Y-Chromosome Male Fertility Gene of Drosqbhila hydei

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 437-446
Author(s):  
Ron Hochstenbach ◽  
Harry Harhangi ◽  
Karin Schouren ◽  
Petra Bindels ◽  
Ron Suijkerbuijk ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Male Fertility ◽  
Fluorescent In Situ Hybridization ◽  
Primary Spermatocyte ◽  
Transcription Unit ◽  
Major Constituent ◽  
Fertility Gene ◽  
Sequence Types ◽  
Gypsy Retrotransposons

Abstract We have found that defective gypsy retrotransposons are a major constituent of the lampbrush loop pair Nooses in the short arm of the Y chromosome of Drosophila hydei. The loop pair is formed by male fertility gene Q during the primary spermatocyte stage of spermatogenesis, each loop being a single transcription unit with an estimated length of 260 kb. Using fluorescent in situ hybridization, we show that throughout the loop transcripts gypsy elements are interspersed with blocks of a tandemly repetitive Y-specific DNA sequence, ay1. Nooses transcripts containing both sequence types show a wide size range on Northern blots, do not migrate to the cytoplasm, and are degraded just before the first meiotic division. Only one strand of ay1 and only the coding strand of gypsy can be detected in the loop transcripts. However, as cloned genomic DNA fragments also display opposite orientations of ay1 and gypsy, such DNA sections cannot be part of the Nooses. Hence, they are most likely derived from the flanking heterochromatin. The direction of transcription of ayl and gypsy thus appears to be of a functional significance.

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