LATE DNA REPLICATION PATTERN IN SEX CHROMOSOMES OF MELANDRIUM

1969 ◽  
Vol 11 (1) ◽  
pp. 192-198 ◽  
Author(s):  
Hiran C. Choudhuri
Keyword(s):  
Dna Replication ◽  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Generation Time ◽  
Replication Pattern ◽  
Interphase Nuclei ◽  
Melandrium Album ◽  
S Period ◽  
Average Generation Time

DNA replication patterns in somatic cells of female and male Meladrium album were studied with autoradiographic methods. The S-period and the average generation time have been estimated to be 5.7 and 15.5 hours respectively. The heterochromatin observed in interphase nuclei may represent the late replicating and presumably inactivated sex chromosome.One arm of one X chromosome is late replicating in females. In the Y chromosome a region near the centromere replicates late in the S-period. The DNA replication sequence in sex chromosomes of female and male cells of Melandrium album suggests that their pattern is similar to that of mammalian sex chromosomes.

Genetic Content of the Neo-Sex Chromosomes in Ctenonotus and Norops (Squamata, Dactyloidae) and Degeneration of the Y Chromosome as Revealed by High-Throughput Sequencing of Individual Chromosomes

2019 ◽  
Vol 157 (1-2) ◽  
pp. 115-122 ◽  
Author(s):  
Artem P. Lisachov ◽  
Alexey I. Makunin ◽  
Massimo Giovannotti ◽  
Jorge C. Pereira ◽  
Anna S. Druzhkova ◽  
...  
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
High Throughput ◽  
Sex Chromosomes ◽  
High Throughput Sequencing ◽  
Anolis Carolinensis ◽  
Pseudoautosomal Region ◽  
Central Component ◽  
Similar System ◽  
Divergence Estimates

Pleurodont lizards are characterized by an ancient system of sex chromosomes. Along with stability of the central component of the system (homologous to the X chromosome of Anolis carolinensis [Dactyloidae], ACAX), in some genera the ancestral sex chromosomes are fused with microautosomes, forming neo-sex chromosomes. The genus Ctenonotus (Dactyloidae) is characterized by multiple X1X1X2X2/X1X2Y sex chromosomes. According to cytogenetic data, the large neo-Y chromosome is formed by fusion of the ancestral Y chromosome with 2 microautosomes (homologous to ACA10 or ACA11 and ACA12), the X1 chromosome is formed by fusion of the ancestral X chromosome with the autosome homologous to ACA10 or ACA11, and the X2 chromosome is homologous to autosome ACA12. To determine more precisely the content and evolution of the Ctenonotus sex chromosomes, we sequenced flow-sorted chromosomes (both sex chromosomes and microautosomes as control) of 2 species with a similar system: C. pogus and C. sabanus. Our results indicate that the translocated part of the X1 is homologous to ACA11, X2 is homologous to ACA12, and the Y contains segments homologous to both ACA11 and ACA12. Molecular divergence estimates suggest that the ancestral X-derived part has completely degenerated in the Y of Ctenonotus, similar to the degeneration of the Norops sagrei Y chromosome (Dactyloidae). The newly added regions show loss of DNA content, but without degeneration of the conserved regions. We hypothesize that the translocation of autosomal blocks onto sex chromosomes facilitated rapid degeneration of the pseudoautosomal region on the ancestral Y.

scholarly journals Guppy Y Chromosome Integrity Maintained by Incomplete Recombination Suppression

2020 ◽  
Vol 12 (6) ◽  
pp. 965-977 ◽  
Author(s):  
Iulia Darolti ◽  
Alison E Wright ◽  
Judith E Mank
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Poecilia Reticulata ◽  
Sex Chromosome ◽  
Rna Seq ◽  
Recombination Suppression ◽  
Sex Chromosome System ◽  
Chromosome Integrity ◽  
Heterogametic Sex

Abstract The loss of recombination triggers divergence between the sex chromosomes and promotes degeneration of the sex-limited chromosome. Several livebearers within the genus Poecilia share a male-heterogametic sex chromosome system that is roughly 20 Myr old, with extreme variation in the degree of Y chromosome divergence. In Poecilia picta, the Y is highly degenerate and associated with complete X chromosome dosage compensation. In contrast, although recombination is restricted across almost the entire length of the sex chromosomes in Poecilia reticulata and Poecilia wingei, divergence between the X chromosome and the Y chromosome is very low. This clade therefore offers a unique opportunity to study the forces that accelerate or hinder sex chromosome divergence. We used RNA-seq data from multiple families of both P. reticulata and P. wingei, the species with low levels of sex chromosome divergence, to differentiate X and Y coding sequences based on sex-limited SNP inheritance. Phylogenetic tree analyses reveal that occasional recombination has persisted between the sex chromosomes for much of their length, as X- and Y-linked sequences cluster by species instead of by gametolog. This incomplete recombination suppression maintains the extensive homomorphy observed in these systems. In addition, we see differences between the previously identified strata in the phylogenetic clustering of X–Y orthologs, with those that cluster by chromosome located in the older stratum, the region previously associated with the sex-determining locus. However, recombination arrest appears to have expanded throughout the sex chromosomes more gradually instead of through a stepwise process associated with inversions.

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.

scholarly journals The Effect of Hybridization on Dosage Compensation in Member Species of the Anopheles gambiae Species Complex

2018 ◽  
Author(s):  
Kevin C. Deitz ◽  
Willem Takken ◽  
Michel A. Slotman
Keyword(s):  
Sex Determination ◽  
Anopheles Gambiae ◽  
Y Chromosome ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Species Complex ◽  
F1 Hybrids ◽  
Chromosome Gene ◽  
Heterogametic Sex

AbstractDosage compensation has evolved in concert with Y-chromosome degeneration in many taxa that exhibit heterogametic sex chromosomes. Dosage compensation overcomes the biological challenge of a "half dose" of X chromosome gene transcripts in the heterogametic sex. The need to equalize gene expression of a hemizygous X with that of autosomes arises from the fact that the X chromosomes retain hundreds of functional genes that are actively transcribed in both sexes and interact with genes expressed on the autosomes. Sex determination and heterogametic sex chromosomes have evolved multiple times in Diptera, and in each case the genetic control of dosage compensation is tightly linked to sex determination. In the Anopheles gambiae species complex (Culicidae), maleness is conferred by the Y-chromosome gene Yob, which despite its conserved role between species is polymorphic in its copy number between them. Previous work demonstrated that male An. gambiae s.s. males exhibit complete dosage compensation in pupal and adult stages. In the present study we have extended this analysis to three sister species in the An. gambiae complex: An. coluzzii, An. arabiensis, and An. quadriannulatus. In addition, we analyzed dosage compensation in bi-directional F1 hybrids between these species to determine if hybridization results in the mis-regulation and disruption of dosage compensation. Our results confirm that dosage compensation operates in the An. gambiae species complex through the hyper-transcription of the male X chromosome. Additionally, dosage compensation in hybrid males does not differ from parental males, indicating that hybridization does not result in the mis-regulation of dosage compensation.

Chromosomes of Onchocerca volvulus (Spirurida:Onchocercidae): A comparative study between Nigeria and Guatemala

1987 ◽  
Vol 61 (1) ◽  
pp. 43-46 ◽  
Author(s):  
H. Hirai ◽  
I. Tada ◽  
H. Takahashi ◽  
B. E. B. Nwoke ◽  
G. O. Ufomadu
Keyword(s):  
Comparative Study ◽  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Onchocerca Volvulus

ABSTRACTChromosomes of Nigerian Onchocerca volvulus were compared with those of Guatemalan O. volvulus. Both parasites had basically the same chromosomal construct (2n=8, XY type). Autosomes consisted of a pair of large and two smaller pairs. Sex chromosomes were made up of medium sized X chromosome and very small Y chromosome. It was not possible to infer the position of the centromeres.

scholarly journals Patterns of DNA variation between the autosomes, the X chromosome and the Y chromosome in Bos taurus genome

2020 ◽  
Author(s):  
Bartosz Czech ◽  
Bernt Guldbrandtsen ◽  
Joanna Szyda
Keyword(s):  
Genetic Variation ◽  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Dna Sequences ◽  
Bovine Genome ◽  
Effective Population ◽  
Accurate Identification ◽  
Nucleotide Divergence ◽  
Tajima’S D

ABSTRACTThe new ARS-UCD1.2 assembly of the bovine genome has considerable improvements. That might be assumed that a more accurate identification of patterns of genetic variation can be achieved with it. We explored differences in genetic variation between autosomes, the X chromosome, and the Y chromosome. In particular, densities of variants, annotation, lengths (only for InDels), nucleotide divergence, and Tajima’s D statistic between chromosomes. Whole-genome DNA sequences of 217 individuals representing different cattle breeds were examined. The analysis included the alignment to the new reference genome and variant calling. 23,655,295 SNPs and 3,758,781 InDels were detected. In contrast to autosomes, both sex chromosomes had negative values of Tajima’s D and lower nucleotide divergence. That implies a correlation between nucleotide diversity and recombination rate, which is obviously reduced for sex chromosomes. Moreover, accumulation of nonsynonymous mutations on the Y chromosome could be associated with loss of recombination. Also, the relatively lower effective population size for sex chromosomes leads to a lower expected density of variants.

C- AND G-BANDS OF THE OPOSSUM CHROMOSOMES: TERMINAL SEQUENCES OF DNA REPLICATION

1976 ◽  
Vol 18 (1) ◽  
pp. 195-205 ◽  
Author(s):  
Anil K. Sinha ◽  
Surabhi Kakati
Keyword(s):  
Dna Replication ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Mammalian Species ◽  
C Banding ◽  
Ph Values ◽  
Different Types

The sex chromosomes of the opossum, Didelphys virginiana, are the only elements that exhibit C-banding. In contrast, the sex chromosomes as well as the autosomes bear specific G-Bands. However, unlike other mammalian species different types of G-banding are observed if the chromosomes are pretreated with trypsin and SSC solution. The SSC pretreated chromosomes show discrete bands only when stained with Giemsa at certain pH values. An asynchronous pattern of terminal DNA replication is observed among the three C-banding regions of the X-chromosome. The inter- and intrapositive G-banding areas of the chromosomes are not always late in DNA replication in comparison to those negatively stained G-banding areas.

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 CYTOGENETIC ANALYSIS OF A SEGMENT OF THE Y CHROMOSOME OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 107 (4) ◽  
pp. 591-610
Author(s):  
Robert W Hardy ◽  
Dan L Lindsley ◽  
Kenneth J Livak ◽  
Barbara Lewis ◽  
Annegrethe L Siversten ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Y Chromosome ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Male Sterile ◽  
Metaphase Chromosomes ◽  
Chromosome Nondisjunction ◽  
In Cells

ABSTRACT Males carrying a large deficiency in the long arm of the Y chromosome known to delete the fertility gene kl-2 are sterile and exhibit a complex phenotype: (1) First metaphase chromosomes are irregular in outline and appear sticky; (2) spermatids contain micronuclei; (3) the nebenkerns of the spermatids are nonuniform in size; (4) a high molecular weight protein ordinarily present in sperm is absent; and (5) crystals appear in the nucleus and cytoplasm of spermatocytes and spermatids. In such males that carry Ste  + on their X chromosome the crystals appear long and needle shaped; in Ste males the needles are much shorter and assemble into star-shaped aggregates. The large deficiency may be subdivided into two shorter component deficiencies. The more distal is male sterile and lacks the high molecular weight polypeptide; the more proximal is responsible for the remainder of the phenotype. Ste males carrying the more proximal component deficiency are sterile, but Ste  + males are fertile. Genetic studies of chromosome segregation in such males reveal that (1) both the sex chromosomes and the large autosomes undergo nondisjunction, (2) the fourth chromosomes disjoin regularly, (3) sex chromosome nondisjunction is more frequent in cells in which the second or third chromosomes nondisjoin than in cells in which autosomal disjunction is regular, (4) in doubly exceptional cells, the sex chromosomes tend to segregate to the opposite pole from the autosomes and (5) there is meiotic drive; i.e., reciprocal meiotic products are not recovered with equal frequencies, complements with fewer chromosomes being recovered more frequently than those with more chromosomes. The proximal component deficiency can itself be further subdivided into two smaller component deficiencies, both of which have nearly normal spermatogenic phenotypes as observed in the light microscope. Meiosis in Ste  + males carrying either of these small Y deficiencies is normal; Ste males, however, exhibit low levels of sex chromosome nondisjunction with either deficient Y. The meiotic phenotype is apparently sensitive to the amount of Y chromosome missing and to the Ste constitution of the X chromosome.

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