scholarly journals Multiple Roles of the Y Chromosome in the Biology ofDrosophila melanogaster

2010 ◽  
Vol 10 ◽  
pp. 1749-1767 ◽  
Author(s):  
Roberto Piergentili
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Nucleolar Organizer ◽  
Fruit Fly ◽  
Phenotypic Traits ◽  
Accurate Analysis ◽  
Intrinsic Nature ◽  
Eye Color ◽  
Genetic Imprinting ◽  
Dna 2

The X and Y chromosomes ofDrosophila melanogasterwere the first examples of chromosomes associated with genetic information. Thanks to the serendipitous discovery of a male with white eyes in 1910, T.H. Morgan was able to associate the X chromosome of the fruit fly with a phenotypic character (the eye color) for the first time. A few years later, his student, C.B. Bridges, demonstrated that X0 males, although phenotypically normal, are completely sterile. This means that the X chromosome, like the autosomes, harbors genes that control several phenotypic traits, while the Y chromosome is important for male fertility only. Notwithstanding its long history – almost 100 years in terms of genetic studies – most of the features of the Y chromosome are still a mystery. This is due to the intrinsic nature of this genetic element, namely, (1) its molecular composition (mainly transposable elements and satellite DNA), (2) its genetic inertia (lack of recombination due to its heterochromatic nature), (3) the absence of homology with the X (with the only exception of the nucleolar organizer), (4) the lack of visible phenotypes when it is missing (indeed, except for their sterility, X0 flies are normal males), and (5) its low density as for protein-coding sequences (to date, only 13 genes out of approximately 14,000 have been mapped on this chromosome inD. melanogaster, i.e., ~0.1% of the total). Nonetheless, a more accurate analysis reveals that this chromosome can influence several complex phenotypes: (1) it has a role in the fertility of both sexes and viability of males when over-represented; (2) it can unbalance the intracellular nucleotide pool; (3) it can interfere with the gene expression either by recruiting proteins involved in chromatin remodeling (PEV) or, to a higher extent, by influencing the expression of up to 1,000 different genes, probably by changing the availability of transcription factors; (4) it plays a major role (up to 50%) in the resistance to heat-induced male sterility; (5) it affects the behavior; and (6) it plays a role in genetic imprinting. In the present paper, all these Y-related phenotypes are described and a potential similarity with the human Y chromosome is drawn.

Studies of the X chromosome of Anopheles albimanus

1985 ◽  
Vol 27 (1) ◽  
pp. 74-82
Author(s):  
J. A. Seawright ◽  
M. Q. Benedict ◽  
S. Narang
Keyword(s):  
X Chromosome ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Chromosome Analysis ◽  
Anopheles Albimanus ◽  
Eye Color ◽  
Colour Mutant ◽  
Translocation Breakpoints ◽  
Radiation Induced

Snow (sn) is a recessive, eye color mutant that is phenotypically indistinguishable from the previously described mutant, white eye (we). The loci for these mutants are over 30 map units apart on the X chromosome. Analysis of salivary gland chromosomes of radiation-induced X-autosome translocations were used to define the positions of sn and we on the distal euchromatic portion of the long arm of the X chromosome. A recessive lethal trait (bubble head) was also mapped relative to we and sn, and the gene order on the long arm of the X chromosome is as follows: centromere – ? – snow – bubble head – white eye. Translocation breakpoints in the euchromatic portion of the X chromosome caused sterility or lethality in males hemizygous for the translocations, but breaks in the heterochromatin had no effect. Crossing-over was greatly reduced when translocation breakpoints were located in the euchromatic part of the X chromosome. The translocations were used to determine that the nucleolar organizer region is probably on the short arm of the X chromosome.Key words: Anopheles albimanus, eye colour mutant, X chromosome.

Analysis of the sex chromosomes of the Mediterranean fruit fly by microdissected DNA probes

Genome ◽  
1998 ◽  
Vol 41 (1) ◽  
pp. 74-78 ◽  
Author(s):  
Ute Willhoeft ◽  
Jutta Mueller-Navia ◽  
Gerald Franz
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Fruit Fly ◽  
Mediterranean Fruit Fly ◽  
Oligonucleotide Primer ◽  
Mitotic Chromosomes ◽  
Degenerate Oligonucleotide ◽  
The Mediterranean

In the Mediterranean fruit fly, Ceratitis capitata, the sex-determining region maps to the long arm of the Y chromosome. DNA from this region of the Y chromosome and, for comparison, from the tip of the long arm of the X chromosome, was isolated by microdissection and amplified by degenerate oligonucleotide primer PCR (DOP-PCR). FISH of the Y-chromosomal microdissection products medY1-medY5 to mitotic chromosomes revealed hybridization signals on most of the long arm of the Y chromosome, including the male-determining region, and on the long arm of the X chromosome, as well as weaker signals on the autosomes, some of which were located in the heterochromatin next to the centromeres. The X-chromosomal microdissected probe medX1 revealed strong signals on the sex chromosomes and randomly distributed signals on the autosomes. Chromosomal in situ suppression hybridization indicates that the Y chromosome contains considerable amounts of Y-enriched and Y-specific sequences and that X-enriched sequences are present on the long arm of the X chromosome. The microdissected probes medY1, medY2, and medX1 hybridize to the sex chromosomes of two closely related species,Ceratitis rosa and Trirhithrum coffeae.

The Karyotype of Blainville’s Beaked Whale, Mesoplodon densirostris

2020 ◽  
pp. 1-6
Author(s):  
Ross Brookwell ◽  
Kimberly Finlayson ◽  
Jason P. van de Merwe
Keyword(s):  
Chromosome Number ◽  
Y Chromosome ◽  
X Chromosome ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Large Block ◽  
Beaked Whale

The karyotype of the Odontocete whale, <i>Mesoplodon densirostris</i>, has not been previously reported. The chromosome number is determined to be 2n = 42, and the karyotype is presented using G-, C-, and nucleolar organizer region (NOR) banding. The findings include NOR regions on 2 chromosomes, regions of heterochromatic variation, a large block of heterochromatin on the X chromosome, and a relatively large Y chromosome. The karyotype is compared to published karyograms of 2 other species of <i>Mesoplodon</i>.

scholarly journals Nucleolar organizer regions, satellite associations and nucleoli of goat cells (<i>Capra hircus</i>)

2009 ◽  
Vol 52 (2) ◽  
pp. 177-186 ◽  
Author(s):  
K. Andraszek ◽  
E. Horoszewicz ◽  
E. Smalec
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Nucleolar Organizer ◽  
Capra Hircus ◽  
Nucleolar Organizer Regions ◽  
Agno3 Solution ◽  
Meiotic Chromosomes ◽  
Satellite Associations ◽  
Active Nors ◽  
In Cells

Abstract. The Polish White Improved goat karyotype consists of 29 pairs of acrocentric autosomes, a large acrocentric X chromosome and a metacentric Y chromosome which is the smallest in the karyotype. Staining of chromosomes with AgNO,sub>3 solution has revealed active nucleolar organizer regions (NOR) in terminal parts of q arms of pair 2, 3, 4, 5, and 28 chromosomes. Out of the total of 100 analysed cells 736 active NORs have been found, on average 7.4±0.2 per cell. Active NORs were most frequently observed in pair 2, and 3 chromosomes, most rarely on pair 5 chromosomes. In all the analysed cells 141, satellite associations (SA) were observed, on average 1.4±0.2 per cell. SAs most often occurred in cells with seven active NORs, and least often in cells with three or four nucleolar organizer regions. Most frequently in SAs the presence of pair 2, 3 and 28 chromosomes was observed. On meiotic chromosomes staining with AgNO3 solution revealed two nucleoli stained with different intensity. Both nucleoli in the cell were of similar size.

Evolution of a Y Chromosome from an X Chromosome

2019 ◽  
Author(s):  
Roberta Bergero ◽  
Jim Gardner ◽  
Deborah Charlesworth
Keyword(s):  
Y Chromosome ◽  
X Chromosome

scholarly journals Recombination between the mouse Y chromosome short arm and an additional Y short arm-derived chromosomal segment attached distal to the X chromosome PAR

Chromosoma ◽  
2015 ◽  
Vol 125 (2) ◽  
pp. 177-188
Author(s):  
Fanny Decarpentrie ◽  
Obah A. Ojarikre ◽  
Michael J. Mitchell ◽  
Paul S. Burgoyne
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Chromosomal Segment

Roles of Anti-Müllerian hormone (Amh) and its duplicates in sex determination and germ cell proliferation of Nile tilapia

Genetics ◽  
2021 ◽  
Author(s):  
Xingyong Liu ◽  
Shengfei Dai ◽  
Jiahong Wu ◽  
Xueyan Wei ◽  
Xin Zhou ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Sex Determination ◽  
Germ Cell ◽  
Y Chromosome ◽  
X Chromosome ◽  
Nile Tilapia ◽  
Critical Period ◽  
Sex Reversal ◽  
Homozygous Mutation ◽  
Germ Cell Proliferation

Abstract Duplicates of amh are crucial for fish sex determination and differentiation. In Nile tilapia, unlike in other teleosts, amh is located on X chromosome. The Y chromosome amh (amh△-y) is mutated with 5 bp insertion and 233 bp deletion in the coding sequence, and tandem duplicate of amh on Y chromosome (amhy) has been identified as the sex determiner. However, the expression of amh, amh△-y and amhy, their roles in germ cell proliferation and the molecular mechanism of how amhy determines sex is still unclear. In this study, expression and functions of each duplicate were analyzed. Sex reversal occurred only when amhy was mutated as revealed by single, double and triple mutation of the three duplicates in XY fish. Homozygous mutation of amhy in YY fish also resulted in sex reversal. Earlier and higher expression of amhy/Amhy was observed in XY gonads compared with amh/Amh during sex determination. Amhy could inhibit the transcription of cyp19a1a through Amhr2/Smads signaling. Loss of cyp19a1a rescued the sex reversal phenotype in XY fish with amhy mutation. Interestingly, mutation of both amh and amhy in XY fish or homozygous mutation of amhy in YY fish resulted in infertile females with significantly increased germ cell proliferation. Taken together, these results indicated that up-regulation of amhy during the critical period of sex determination makes it the sex-determining gene, and it functions through repressing cyp19a1a expression via Amhr2/Smads signaling pathway. Amh retained its function in controlling germ cell proliferation as reported in other teleosts, while amh△-y was nonfunctionalized.

Clues from other animals and theoretical considerations

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 3-4
Author(s):  
Anne McLaren
Keyword(s):  
Sex Determination ◽  
Genetic Control ◽  
Y Chromosome ◽  
X Chromosome ◽  
X Chromosomes ◽  
The Third ◽  
Mouse Species ◽  
Primary Male ◽  
Theoretical Considerations ◽  
State Of Activity

In the first two papers of this volume, the genetic control of sex determination in Caenorhabditis and Drosophila is reviewed by Hodgkin and by Nöthiger & Steinmarin-Zwicky, respectively. Sex determination in both cases depends on the ratio of X chromosomes to autosomes, which acts as a signal to a cascade of règulatory genes located either on autosomes or on the X chromosome. The state of activity of the last gene in the sequence determines phenotypic sex. In the third paper, Erickson & Tres describe the structure of the mouse Y chromosome and the polymorphisms that have been detected in different mouse species and strains. As in all mammals, the Y carries the primary male-determining locus; autosomal genes may also be involved in sex determination, but they must act down-stream from the Y-linked locus.

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