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.

Muller’s ratchet of the Y chromosome with gene conversion

Genetics ◽  
2021 ◽  
Author(s):  
Takahiro Sakamoto ◽  
Hideki Innan
Keyword(s):  
Gene Duplication ◽  
Gene Conversion ◽  
Y Chromosome ◽  
Conversion Rate ◽  
Single Copy ◽  
Duplicated Genes ◽  
Fitness Effect ◽  
Muller's Ratchet ◽  
Y Chromosomes ◽  
Muller’S Ratchet

Abstract Muller’s ratchet is a process in which deleterious mutations are fixed irreversibly in the absence of recombination. The degeneration of the Y chromosome, and the gradual loss of its genes, can be explained by Muller’s ratchet. However, most theories consider single-copy genes, and may not be applicable to Y chromosomes, which have a number of duplicated genes in many species, which are probably undergoing concerted evolution by gene conversion. We developed a model of Muller’s ratchet to explore the evolution of the Y chromosome. The model assumes a non-recombining chromosome with both single-copy and duplicated genes. We used analytical and simulation approaches to obtain the rate of gene loss in this model, with special attention to the role of gene conversion. Homogenization by gene conversion makes both duplicated copies either mutated or intact. The former promotes the ratchet, and the latter retards, and we ask which of these counteracting forces dominates under which conditions. We found that the effect of gene conversion is complex, and depends upon the fitness effect of gene duplication. When duplication has no effect on fitness, gene conversion accelerates the ratchet of both single-copy and duplicated genes. If duplication has an additive fitness effect, the ratchet of single-copy genes is accelerated by gene duplication, regardless of the gene conversion rate, whereas gene conversion slows the degeneration of duplicated genes. Our results suggest that the evolution of the Y chromosome involves several parameters, including the fitness effect of gene duplication by increasing dosage and gene conversion rate.

scholarly journals Chromosome Y Isodicentrics in two Cases with Ambiguous genitalia and Features of Turner Syndrome

2008 ◽  
Vol 11 (2) ◽  
pp. 51-58
Author(s):  
A Lungeanu ◽  
A Arghir ◽  
S Arps ◽  
G Cardos ◽  
N Dumitriu ◽  
...  
Keyword(s):  
Turner Syndrome ◽  
Y Chromosome ◽  
Ambiguous Genitalia ◽  
Peripheral Blood Lymphocytes ◽  
Chromosome Y ◽  
Y Chromosomes ◽  
New Information ◽  
Pathway Perturbation

Chromosome Y Isodicentrics in two Cases with Ambiguous genitalia and Features of Turner SyndromeKaryotype investigations using classical cytogenetics, fluorescencein situhybridization (FISH) and polymerase chain reaction (PCR) techniques were used for the characterization of Y chromosome structural anomalies found in two patients with ambiguous genitalia and features of Turner syndrome. Both exhibited mosaic karyotypes of peripheral blood lymphocytes. The karyotype was 45, X[90]/ 46, X, idic(Y)(p11.3).ish idic(Y) (wcpY+, DXYS130++,SRY++,DYZ3++,DYZ1++, DYS224++)[10] in one case, and the karyotype was 45, X[65]/46, X, idic(Y) (q11).ish idic(Y)(SRY++, RP11-140H23-)[35] in the other case. Derivative Y chromosomes were different in shape and size and positive for the SRY gene, a common underlying element of ambiguous genitalia phenotypes. These results add new information concerning the role of Y chromosome structural abnormalities in sex determination pathway perturbation which are poorly understood, and highlight the importance of the sex chromosomes integrity for a normal sex phenotype development.

Y CHROMOSOME HYPERPLOIDY AND MALE FERTILITY IN DROSOPHILA MELANOGASTER

1979 ◽  
Vol 21 (1) ◽  
pp. 21-24 ◽  
Author(s):  
John H. Williamson ◽  
Eva Meidinger
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Mating Behavior ◽  
Male Fertility ◽  
Y Chromosomes

Drosophila melanogaster males with two supernumerary Y chromosomes, i.e. triplo-Y males, are completely sterile. Their mating behavior is normal, and spermatogenesis and spermiogenesis appear normal, but no sperm are transferred. Most, if not all, of the detrimental effects of a third Y chromosome on male fertility are attributable to the long arm of the Y chromosome.

Other genes of the Y chromosome

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 117-118
Author(s):  
Jonathan Wolfe
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Male Fertility ◽  
Major Part ◽  
Essential Genes ◽  
Upper Limit ◽  
Y Chromosomes ◽  
Number Of Genes ◽  
The Moment ◽  
Human And Mouse

From the moment that the major part of the mammalian Y chromosome ceased to recombine with the X, the action of Muller's ratchet began to whittle away at it to remove all but the essential genes. Consequently, by comparison with their respective X homologues, both human and mouse Y chromosomes are relatively small and probably contain very few genes in a fabric of accumulated junk. Nevertheless, molecular biologists have not been deterred from searching for Y-linked genes and in recent years this has become an increasingly popular pastime. Although hard to find, any Y-linked genes are likely to play important roles in either sex determination or male fertility, a fact which has spurred the search. How many genes are likely to be present on the chromosome? If we accept the hypothesis that most genes are preceded by an HpaII tiny fragment (HTF) island, we can place an upper limit on the number of genes by considering the frequency with which such islands occur on the chromosome.

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 Two tests of Y chromosomal variation in male fertility of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 527-534 ◽  
Author(s):  
A G Clark
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Male Fertility ◽  
Genetic Model ◽  
Natural Populations ◽  
Qualitative Behavior ◽  
Male Mating ◽  
Physiological Importance ◽  
Y Chromosomes ◽  
Insight Into

Abstract Deficiency mapping with Y autosome translocations has shown that the Y chromosome of Drosophila melanogaster carries genes that are essential to male fertility. While the qualitative behavior of these lesions provides important insight into the physiological importance of the Y chromosome, quantitative variation in effects on male fertility among extant Y chromosomes in natural populations may have a significant effect on the evolution of the Y chromosome. Here a series of 36 Y chromosome replacement lines were tested in two ways designed to detect subtle variation in effects on male fertility and total male fitness. The first test involved crossing males from the 36 lines to an excess of females in an attempt to measure differences in male mating success (virility) and male fecundity. The second test challenged males bearing each of the 36 Y chromosomes to competition in populations with males bearing a standard, phenotypically marked (BsY) chromosome. These tests indicated that the Y chromosome lines did not differ significantly in either male fertility or total fitness, but that interactions with autosomes approached significance. A deterministic population genetic model was developed allowing Y autosome interaction in fertility, and it is shown that, consistent with the experimental observations, this model cannot protect Y-linked polymorphism.

scholarly journals Y-chromosome structural diversity in the bonobo and chimpanzee lineages

2015 ◽  
Author(s):  
Matthew T. Oetjens ◽  
Feichen Shen ◽  
Sarah B. Emery ◽  
Zhengting Zou ◽  
Jeffrey M. Kidd
Keyword(s):  
Y Chromosome ◽  
Pan Troglodytes ◽  
Male Fertility ◽  
Copy Number ◽  
Tandem Repeats ◽  
Pan Paniscus ◽  
Genome Instability ◽  
Repetitive Sequences ◽  
Structural Diversity ◽  
Y Chromosomes

AbstractThe male specific regions of primate Y-chromosomes (MSY) are enriched for multi-copy genes highly expressed in the testis. These genes are located in large repetitive sequences arranged as palindromes, inverted-, and tandem-repeats termed amplicons. In humans, these genes have critical roles in male fertility and are essential for the production of sperm. The structure of human and chimpanzee amplicon sequences show remarkable difference relative to the remainder of the genome, a difference that may be the result of intense selective pressure on male fertility. Four populations of common chimpanzees have undergone extended periods of isolation and appear to be in the early process of speciation. A recent study found amplicons enriched for testis-expressed genes on the primate X-chromosome the target of hard selective sweeps, and male-fertility genes on the Y-chromosome may also be the targets of selection. However, little is understood about Y-chromosome amplicon diversity within and across chimpanzee populations. Here, we analyze 9 common chimpanzee (representing three subspecies: Pan troglodytes schweinfurthii, Pan troglodytes ellioti, and Pan troglodytes verus) and two bonobo (Pan paniscus) male whole-genome sequences to assess Y ampliconic copy-number diversity across the Pan genus. We observe that the copy-number of Y chromosome amplicons is variable amongst chimpanzees and bonobos, and identify several lineage-specific patterns, including variable copy-number of azoospermia candidates RBMY and DAZ. We detect recurrent switchpoints of copy-number change along the ampliconic tracts across chimpanzee populations, which may be the result of localized genome instability or selective forces.

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.

Concurrent Electrodermal and Eyeblink Conditioning With Masked and Unmasked Stimuli

2021 ◽  
Vol 35 (1) ◽  
pp. 35-42
Author(s):  
José Luis Marcos ◽  
Azahara Marcos
Keyword(s):  
Unconditioned Stimulus ◽  
Strong Evidence ◽  
Eyeblink Conditioning ◽  
Noise Burst ◽  
Conditioning Phase ◽  
Contingency Awareness ◽  
Blank Screen ◽  
Neutral Face ◽  
Fearful Face

Abstract. The aim of this study was to determine if contingency awareness between the conditioned (CS) and unconditioned stimulus (US) is necessary for concurrent electrodermal and eyeblink conditioning to masked stimuli. An angry woman’s face (CS+) and a fearful face (CS−) were presented for 23 milliseconds (ms) and followed by a neutral face as a mask. A 98 dB noise burst (US) was administered 477 ms after CS+ offset to elicit both electrodermal and eyeblink responses. For the unmasking conditioning a 176 ms blank screen was inserted between the CS and the mask. Contingency awareness was assessed using trial-by-trial ratings of US-expectancy in a post-conditioning phase. The results showed acquisition of differential electrodermal and eyeblink conditioning in aware, but not in unaware participants. Acquisition of differential eyeblink conditioning required more trials than electrodermal conditioning. These results provided strong evidence of the causal role of contingency awareness on differential eyeblink and electrodermal conditioning.

BLOCKADE OF THE SURGE OF PROLACTIN AT PRO-OESTRUS BY ADMINISTRATION OF ANTI-OESTROGENIC SUBSTANCE, MER-25

1973 ◽  
Vol 74 (4) ◽  
pp. 769-774 ◽  
Author(s):  
Akira Yokoyama ◽  
Hiroshi Tomogane ◽  
Katuaki Ôta
Keyword(s):  
Strong Evidence ◽  
The Other ◽  
Other Hand

ABSTRACT A non-steroidal oestrogen antagonist, MER-25, was administered to cycling rats for elucidating the role of oestrogen in the surge of prolactin observed on the afternoon of pro-oestrus (POe). In animals injected with 20 mg of MER-25 intramuscularly on the afternoon (16.30 h) of the first day of dioestrus (D-1), the surge of prolactin was blocked while the level of prolactin on the afternoon of POe of these animals was significantly higher than that of the corresponding controls injected with oil. Ovulation was also blocked in these animals treated with the drug on the afternoon of D-l. On the other hand, treatment on the morning (10.30 h) of the 2nd day of dioestrus failed to prevent not only the surge of prolactin but also ovulation. These observations provide strong evidence for the view that oestrogen is responsible for the surge of prolactin on the afternoon of POe, and that the surge is accompanied by that of LH.

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