Chromosomal homology of wood bison and plains bison

1977 ◽  
Vol 55 (10) ◽  
pp. 1759-1762 ◽  
Author(s):  
K. L. Ying ◽  
D. G. Peden
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Bison Bison ◽  
Banding Patterns ◽  
X Chromosomes ◽  
Chromosomal Homology ◽  
Wood Bison

Karyotypes of wood bison (Bison bison athabascae) and plains bison (Bison bison bison) were studied. Both subspecies were characterized by the same number of chromosomes (2n = 60), acrocentric autosomes, submetacentric X chromosomes, and an acrocentric Y chromosome. G-banding patterns suggest that when comparing wood bison and plains bison, 20 pair plus the sex chromosomes are homologous. Whether or not the remaining nine pair of chromosomes are homologous remains unknown.

HYBRIDIZATION BETWEEN THE NEARCTIC ANOPHELES PUNCTIPENNIS AND THE PALEARCTIC ANOPHELES ATROPARVUS

1977 ◽  
Vol 19 (2) ◽  
pp. 265-270
Author(s):  
Richard D. Kreutzer
Keyword(s):  
Salivary Gland ◽  
Chromosome Banding ◽  
Interspecific Crosses ◽  
Inverted Region ◽  
Banding Patterns ◽  
X Chromosomes ◽  
Chromosomal Homology ◽  
Anopheles Atroparvus ◽  
Palearctic Species ◽  
High Level

Interspecific crosses were made between the Palearctic species Anopheles atroparvus Van Thiel and the Nearctic species A. punctipennis Say. Except for most of the X chromosomes, an inverted region in 3R, and band intensity differences the salivary gland chromosome banding patterns are the same in both species. Despite this high level of chromosomal homology very little synapsis of identically banded regions was observed in hybrid complements. This asynapsis and the fact that no adults were produced from either the cross or the reciprocal indicate that there are significant genetic differences between the species.

scholarly journals MITOTIC RECOMBINATION IN THE HETEROCHROMATIN OF THE SEX CHROMOSOMES OF DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 90 (1) ◽  
pp. 93-104
Author(s):  
P Ripoll ◽  
A Garcia-Bellido
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Mitotic Recombination ◽  
X Chromosomes ◽  
X Ray ◽  
Y Chromosomes ◽  
Chromosome Arm

ABSTRACT The frequency of spontaneous and X-ray-induced mitotic recombination involving the Y chromosome has been studied in individuals with a marked Y chromosome arm and different XY compound chromosomes. The genotypes used include X chromosomes with different amounts of X heterochromatin and either or both arms of the Y chromosome attached to either side of the centromere. Individuals with two Y chromosomes have also been studied. The results show that the bulk of mitotic recombination takes place between homologous regions.

scholarly journals Heterochromatin variation in chromosomes of Anopheles (Nyssorhynchus) darlingi Root and A.(N.) nuneztovari Gabaldón (Diptera: Culicidae)

2000 ◽  
Vol 23 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Míriam Silva Rafael ◽  
Wanderli Pedro Tadei
Keyword(s):  
Y Chromosome ◽  
Intraspecific Variation ◽  
Sex Chromosomes ◽  
Centromeric Region ◽  
Anopheles Darlingi ◽  
X Chromosomes ◽  
C Banding ◽  
Heterochromatic Block ◽  
Chromosome Ii ◽  
Two Populations

C-banding was used to study the variations in heterochromatic block markings in chromosomes of Anopheles darlingi and A. nuneztovari from Manaus, State of Amazonas, and Macapá, State of Amapá, Brazil. Both species had two differently shaped X chromosomes and a Y chromosome that was entirely heterochromatic. The X1 chromosome of A. darlingi had markings that extended 1/3 of the total length whereas in the X2 chromosome the markings were located around the centromeric region. The markings on autosomal chromosomes were concentrated in the centromeric region in both species, with a heterochromatic block in one arm of chromosome II of A. darlingi. A. nuneztovari had three heterochromatic blocks in chromosome X1 (longer) and two blocks in X2 (shorter). X2X2 females were not detected in either species. The X1 and X2 chromosomes of males were found in A. darlingi, whereas in A. nuneztovari only the X1 chromosome was detected. Only intraspecific variation was found in heterochromatic block markings in the sex chromosomes and autosomes in the two populations of both species at each location.

The polytene chromosomes of Simulium furculatum (Shewell) (Diptera: Simuliidae)

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 522-530
Author(s):  
Fiona F. Hunter
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Polytene Chromosomes ◽  
Species Group ◽  
Western Canada ◽  
Black Flies ◽  
X Chromosomes ◽  
Group A ◽  
Sex Chromosome System

To test whether Simulium furculatum (Shewell) belongs to the Simulium vernum (Macquart) species-group, a comparison was made of the polytene chromosomes of S. furculatum and the S. vernum "Knebworth" standard. Only two chromosome arms (of six) could be completely analysed. It is argued that S. furculatum does not belong to the S. vernum species-group. A complex sex-chromosome system (X1, X2, Y1) is found in both eastern and western Canada. Phylogenetically, the single Y chromosome is intermediate between the two X chromosomes. Intraspecific inversion polymorphisms, which serve to differentiate eastern from western populations, are also identified. Only one sibling is indicated.Key words: black flies, Simulium furculatum, Simulium vernum, cytotaxonomy, polytene chromosomes, sex chromosomes.

BANDING PATTERNS IN MITOTIC CHROMOSOMES OF THE RABBIT (ORYCTOLAGUS CUNICULUS)

1977 ◽  
Vol 19 (4) ◽  
pp. 625-632 ◽  
Author(s):  
F. P. H. Chan ◽  
F. R. Sergovich ◽  
E. L. Shaver
Keyword(s):  
Detailed Analysis ◽  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Banding Pattern ◽  
Oryctolagus Cuniculus ◽  
Acrocentric Chromosome ◽  
Mitotic Chromosomes ◽  
Banding Patterns ◽  
Medium Length

A detailed analysis of rabbit mitotic chromosomes stained with quinacrine and Trypsin-Giemsa methods to elucidate the Q and G bands is presented. Each of the 21 pairs of autosomes can be identified unequivocally. The sex chromosomes can also be distinguished from the autosomes. The X chromosome is a medium length submetacentric with its own distinctive banding pattern. The Y chromosome is the smallest acrocentric chromosome and fluoresces with a medium intensity.

scholarly journals Structural changes following the reversal of a Y Chromosome to an autosome in Drosophila pseudoobscura

2016 ◽  
Author(s):  
Ching-Ho Chang ◽  
Amanda M. Larracuente
Keyword(s):  
Y Chromosome ◽  
Single Molecule ◽  
Sex Chromosomes ◽  
Structural Changes ◽  
Drosophila Pseudoobscura ◽  
X Chromosomes ◽  
Repeat Content ◽  
Y Chromosomes ◽  
Rapid Sequence ◽  
Compact Size

AbstractRobertsonian translocations resulting in fusions between sex chromosomes and autosomes shape karyotype evolution in animals by creating new sex chromosomes from autosomes. These translocations can also reverse sex chromosomes back into autosomes, which is especially intriguing given that autosomes and sex chromosomes differ in gene regulation and chromatin environment. While researchers are beginning to understand X chromosomes reversals to autosomes at a genomic level, it is difficult to study reversals of Y chromosomes because of their rapid sequence turnover and high repeat content. To gain insight into the genomic events following a Y chromosome reversal, we investigated an autosome-Y translocation in a well-studied and tractable organism, Drosophila pseudoobscura. About 10-15 Mya, the ancestral Y chromosome fused to a small autosome (the dot chromosome) in an ancestor of D. pseudoobscura. We used single molecule real-time sequencing reads to assemble the genic part of the D. pseudoobscura dot chromosome, including this Y-to-dot translocation. We find that the intervening sequence between the ancestral Y and the rest of the dot chromosome is only ~78 Kb and has a low repeat density, suggesting that the centromere now falls outside, rather than between, the fused chromosomes. The Y-to-dot region is 100 times smaller than the D. melanogaster Y chromosome, owing to repeat landscape changes. Previous studies suggest that recurrent selective sweeps favoring shorter introns helped to shrink the Y-to-dot following the translocation. Our results suggest that genetic drift and a small ancestral Y chromosome may also help explain the compact size of the Y-to-dot translocation.

scholarly journals Epigenetics drive the evolution of sex chromosomes in animals and plants

2021 ◽  
Vol 376 (1826) ◽  
Author(s):  
Aline Muyle ◽  
Doris Bachtrog ◽  
Gabriel A. B. Marais ◽  
James M. A. Turner
Keyword(s):  
Transposable Elements ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Binding Motif ◽  
X Chromosomes ◽  
Meiotic Sex Chromosome Inactivation ◽  
Compensation Mechanisms ◽  
Male Specific Lethal ◽  
Male Specific

We review how epigenetics affect sex chromosome evolution in animals and plants. In a few species, sex is determined epigenetically through the action of Y-encoded small RNAs. Epigenetics is also responsible for changing the sex of individuals through time, even in species that carry sex chromosomes, and could favour species adaptation through breeding system plasticity. The Y chromosome accumulates repeats that become epigenetically silenced which leads to an epigenetic conflict with the expression of Y genes and could accelerate Y degeneration. Y heterochromatin can be lost through ageing, which activates transposable elements and lowers male longevity. Y chromosome degeneration has led to the evolution of meiotic sex chromosome inactivation in eutherians (placentals) and marsupials, and dosage compensation mechanisms in animals and plants. X-inactivation convergently evolved in eutherians and marsupials via two independently evolved non-coding RNAs. In Drosophila , male X upregulation by the male specific lethal (MSL) complex can spread to neo-X chromosomes through the transposition of transposable elements that carry an MSL-binding motif. We discuss similarities and possible differences between plants and animals and suggest future directions for this dynamic field of research. This article is part of the theme issue ‘How does epigenetics influence the course of evolution?’

scholarly journals Bisection of the X chromosome disrupts the initiation of chromosome silencing during meiosis in Caenorhabditis elegans

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yisrael Rappaport ◽  
Hanna Achache ◽  
Roni Falk ◽  
Omer Murik ◽  
Oren Ram ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Rna Polymerase Ii ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Transcription Analysis ◽  
X Chromosomes ◽  
Unique Character ◽  
Active Transcription ◽  
Heterogametic Sex

AbstractDuring meiosis, gene expression is silenced in aberrantly unsynapsed chromatin and in heterogametic sex chromosomes. Initiation of sex chromosome silencing is disrupted in meiocytes with sex chromosome-autosome translocations. To determine whether this is due to aberrant synapsis or loss of continuity of sex chromosomes, we engineered Caenorhabditis elegans nematodes with non-translocated, bisected X chromosomes. In early meiocytes of mutant males and hermaphrodites, X segments are enriched with euchromatin assembly markers and active RNA polymerase II staining, indicating active transcription. Analysis of RNA-seq data showed that genes from the X chromosome are upregulated in gonads of mutant worms. Contrary to previous models, which predicted that any unsynapsed chromatin is silenced during meiosis, our data indicate that unsynapsed X segments are transcribed. Therefore, our results suggest that sex chromosome chromatin has a unique character that facilitates its meiotic expression when its continuity is lost, regardless of whether or not it is synapsed.

scholarly journals Localization of Male-Specifically Expressed MROS Genes of Silene latifolia by PCR on Flow-Sorted Sex Chromosomes and Autosomes

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1269-1277
Author(s):  
Eduard Kejnovský ◽  
Jan Vrána ◽  
Sachihiro Matsunaga ◽  
Přemysl Souček ◽  
Jiří Široký ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Homology Search ◽  
X Chromosomes ◽  
Dioecious Plants ◽  
Flow Sorting ◽  
Heteromorphic Sex Chromosomes ◽  
Copy Gene ◽  
Melandrium Album ◽  
Pcr Products

Abstract The dioecious white campion Silene latifolia (syn. Melandrium album) has heteromorphic sex chromosomes, XX in females and XY in males, that are larger than the autosomes and enable their separation by flow sorting. The group of MROS genes, the first male-specifically expressed genes in dioecious plants, was recently identified in S. latifolia. To localize the MROS genes, we used the flow-sorted X chromosomes and autosomes as a template for PCR with internal primers. Our results indicate that the MROS3 gene is located in at least two copies tandemly arranged on the X chromosome with additional copy(ies) on the autosome(s), while MROS1, MROS2, and MROS4 are exclusively autosomal. The specificity of PCR products was checked by digestion with a restriction enzyme or reamplification using nested primers. Homology search of databases has shown the presence of five MROS3 homologues in A. thaliana, four of them arranged in two tandems, each consisting of two copies. We conclude that MROS3 is a low-copy gene family, connected with the proper pollen development, which is present not only in dioecious but also in other dicot plant species.

scholarly journals X and Y Chromosome Complement Influence Adiposity and Metabolism in Mice

Endocrinology ◽  
2013 ◽  
Vol 154 (3) ◽  
pp. 1092-1104 ◽  
Author(s):  
Xuqi Chen ◽  
Rebecca McClusky ◽  
Yuichiro Itoh ◽  
Karen Reue ◽  
Arthur P. Arnold
Keyword(s):  
Body Weight ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Chromosome Complement ◽  
Gonadal Hormones ◽  
Xy Model ◽  
Second Sex ◽  
Metabolic Variables ◽  
Novel Model

Abstract Three different models of MF1 strain mice were studied to measure the effects of gonadal secretions and sex chromosome type and number on body weight and composition, and on related metabolic variables such as glucose homeostasis, feeding, and activity. The 3 genetic models varied sex chromosome complement in different ways, as follows: 1) “four core genotypes” mice, comprising XX and XY gonadal males, and XX and XY gonadal females; 2) the XY* model comprising groups similar to XO, XX, XY, and XXY; and 3) a novel model comprising 6 groups having XO, XX, and XY chromosomes with either testes or ovaries. In gonadally intact mice, gonadal males were heavier than gonadal females, but sex chromosome complement also influenced weight. The male/female difference was abolished by adult gonadectomy, after which mice with 2 sex chromosomes (XX or XY) had greater body weight and percentage of body fat than mice with 1 X chromosome. A second sex chromosome of either type, X or Y, had similar effects, indicating that the 2 sex chromosomes each possess factors that influence body weight and composition in the MF1 genetic background. Sex chromosome complement also influenced metabolic variables such as food intake and glucose tolerance. The results reveal a role for the Y chromosome in metabolism independent of testes and gonadal hormones and point to a small number of X–Y gene pairs with similar coding sequences as candidates for causing these effects.

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