scholarly journals Recombination suppression by heterozygous Robertsonian chromosomes in the mouse.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 649-667
Author(s):  
M T Davisson ◽  
E C Akeson
Keyword(s):  
Genetic Markers ◽  
Centromeric Region ◽  
Genetic Recombination ◽  
Underlying Mechanism ◽  
Meiotic Pairing ◽  
Linkage Studies ◽  
Recombination Suppression ◽  
Telocentric Chromosomes ◽  
Mechanical Interference ◽  
Structural Differences

Abstract Robertsonian chromosomes are metacentric chromosomes formed by the joining of two telocentric chromosomes at their centromere ends. Many Robertsonian chromosomes of the mouse suppress genetic recombination near the centromere when heterozygous. We have analyzed genetic recombination and meiotic pairing in mice heterozygous for Robertsonian chromosomes and genetic markers to determine (1) the reason for this recombination suppression and (2) whether there are any consistent rules to predict which Robertsonian chromosomes will suppress recombination. Meiotic pairing was analyzed using synaptonemal complex preparations. Our data provide evidence that the underlying mechanism of recombination suppression is mechanical interference in meiotic pairing between Robertsonian chromosomes and their telocentric partners. The fact that recombination suppression is specific to individual Robertsonian chromosomes suggests that the pairing delay is caused by minor structural differences between the Robertsonian chromosomes and their telocentric homologs and that these differences arise during Robertsonian formation. Further understanding of this pairing delay is important for mouse mapping studies. In 10 mouse chromosomes (3, 4, 5, 6, 8, 9, 10, 11, 15 and 19) the distances from the centromeres to first markers may still be underestimated because they have been determined using only Robertsonian chromosomes. Our control linkage studies using C-band (heterochromatin) markers for the centromeric region provide improved estimates for the centromere-to-first-locus distance in mouse chromosomes 1, 2 and 16.

Sampling strategy in linkage studies of affective disorders

1990 ◽  
Vol 20 (3) ◽  
pp. 573-579 ◽  
Author(s):  
M. Leboyer ◽  
M. C. Babron ◽  
F. Clerget-Darpoux
Keyword(s):  
Genetic Markers ◽  
Genetic Heterogeneity ◽  
Affective Disorders ◽  
Sampling Strategy ◽  
Linkage Studies ◽  
Chromosome X ◽  
Nuclear Families ◽  
Bipolar Patients ◽  
Degree Of Heterogeneity

SynopsisEvidence of linkage in families of bipolar patients has so far been identified with genetic markers on chromosome X and 11. However, replications of these data have not consistently been reported in either case, which favours the hypothesis of genetic heterogeneity. Therefore, we have tried to outline a sampling strategy for linkage replication in affective disorders. We estimated the average number of nuclear families required to replicate X or 11 linkage as a function of the degree of heterogeneity as well as the number to prove heterogeneity given that linkage exists. The results are presented and discussed.

Zebrafish: chiasmata and interference

Genome ◽  
2006 ◽  
Vol 49 (3) ◽  
pp. 205-208 ◽  
Author(s):  
Peter B Moens
Keyword(s):  
Danio Rerio ◽  
Random Distribution ◽  
Immunofluorescence Microscopy ◽  
Centromeric Region ◽  
Genetic Recombination ◽  
Protein A ◽  
Mlh1 Foci ◽  
Distal Localization ◽  
Single Focus ◽  
Chiasma Interference

With immunofluorescence microscopy, the positions of centromeres and MLH1 (MutL homolog) foci representing the sites of presumptive chiasmata are shown for zebrafish (Danio rerio Hamilton 1822) synaptonemal complexes (SCs) in spermatocyte nuclei at meiotic prophase. Most SCs have a single focus and a few (7 of 140) have 2 chiasmata. MLH1 foci tend to be in the distal regions of SCs, with progressively fewer occurring towards the middle of the SCs. This non-random distribution suggests chiasma interference. Synaptic initiation, as well as replication protein A (RPA) foci at the chromosome ends, correlates with the distal localization of MLH1 foci. These observations may provide the physical basis for the reported limited genetic recombination in the centromeric region of androgenetic offspring of a male.Key words: zebrafish, recombination, chiasmata, interference, MLH1, RPA.

scholarly journals PAIRING COMPETITION BETWEEN IDENTICAL AND HOMOLOGOUS CHROMOSOMES IN RYE AND GRASSHOPPERS

Genetics ◽  
1983 ◽  
Vol 104 (4) ◽  
pp. 677-684
Author(s):  
J L Santos ◽  
J Orellana ◽  
R Giraldez
Keyword(s):  
Secale Cereale ◽  
Banding Pattern ◽  
Chromosome Pair ◽  
Meiotic Pairing ◽  
Homologous Pairing ◽  
Eyprepocnemis Plorans ◽  
Homologous Chromosomes ◽  
Random Pairing ◽  
Structural Differences ◽  
Telomeric Heterochromatin

ABSTRACT Meiotic pairing preferences between identical and homologous but not identical chromosomes were analyzed in spontaneous tetraploid/diploid chimeras of three male grasshoppers (Eyprepocnemis plorans) whose chromosome pair 11 were heterozygous for C-banding pattern and in four induced tetraploid/diploid chimaeral rye plants (Secale cereale) heterozygous for telomeric heterochromatin C-bands in chromosomes 1R and 2R. In the grasshoppers, a preference for identical over homologous pairing was observed, whereas in rye both a preference for homologous rather than identical pairing and random pairing between the four chromosomes of the set was found. From the results in rye, it can be deduced that pairing preferences do not depend exclusively on the similarities between chromosomes involved. It is suggested that genotypic or cryptic structural differences between the homologous chromosomes of each pair analyzed might be responsible for the pairing preferences found. This hypothesis can also explain the results obtained in grasshoppers, although the possibility of premeiotic association cannot be excluded in this material.

scholarly journals Structural and Biophysical Analyses of Human N-Myc Downstream-Regulated Gene 3 (NDRG3) Protein

Biomolecules ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 90
Author(s):  
Kyung Rok Kim ◽  
Kyung A. Kim ◽  
Joon Sung Park ◽  
Jun Young Jang ◽  
Yuri Choi ◽  
...  
Keyword(s):  
Cancer Metabolism ◽  
Underlying Mechanism ◽  
Catalytic Triad ◽  
Molecular Characteristics ◽  
Flexible Loop ◽  
Loop Region ◽  
Hydrolase Fold ◽  
Structural Differences ◽  
And Migration ◽  
Proliferation And Migration

The N-Myc downstream-regulated gene (NDRG) family belongs to the α/β-hydrolase fold and is known to exert various physiologic functions in cell proliferation, differentiation, and hypoxia-induced cancer metabolism. In particular, NDRG3 is closely related to proliferation and migration of prostate cancer cells, and recent studies reported its implication in lactate-triggered hypoxia responses or tumorigenesis. However, the underlying mechanism for the functions of NDRG3 remains unclear. Here, we report the crystal structure of human NDRG3 at 2.2 Å resolution, with six molecules in an asymmetric unit. While NDRG3 adopts the α/β-hydrolase fold, complete substitution of the canonical catalytic triad residues to non-reactive residues and steric hindrance around the pseudo-active site seem to disable the α/β-hydrolase activity. While NDRG3 shares a high similarity to NDRG2 in terms of amino acid sequence and structure, NDRG3 exhibited remarkable structural differences in a flexible loop corresponding to helix α6 of NDRG2 that is responsible for tumor suppression. Thus, this flexible loop region seems to play a distinct role in oncogenic progression induced by NDRG3. Collectively, our studies could provide structural and biophysical insights into the molecular characteristics of NDRG3.

A cytological study of intraspecific variation in Ceratopteris thalictroides

1979 ◽  
Vol 57 (16) ◽  
pp. 1694-1700 ◽  
Author(s):  
Leslie G. Hickok
Keyword(s):  
Spore Germination ◽  
Cytological Study ◽  
Meiotic Pairing ◽  
Spore Viability ◽  
Polymorphic Species ◽  
Structural Differences ◽  
Pairing Behavior ◽  
Ceratopteris Thalictroides ◽  
Low Levels ◽  
Intraspecific Hybrids

A cytological study of meiotic pairing behavior in intraspecific hybrids was undertaken utilizing seven different collections of Ceratopteris thalictroides. Two mutant gametophyte stocks with nonfunctional spermatozoids were utilized to facilitate the synthesis of intraspecific hybrids. Low levels of univalent and quadrivalent formation were found in most of the hybrids, indicating that some structural differences existed, but major pairing homologies were still evident. The fertility of hybrids ranged from 10 to 75% spore germination. One collection, from Hawaii, showed high levels of univalent formation and very low spore viability. In that this stock is both biologically and morphologically distinct, it should be given taxonomic recognition. The study, in general, is in agreement with the most recent taxonomic treatment of Ceratopteris in that it shows a significant amount of cytological variation within the polymorphic species C. thalictroides.

scholarly journals Pericentromeric heterochromatin impacts genome compartmentalization and sex chromosome evolution in a fish

2021 ◽  
Author(s):  
Lingzhan Xue ◽  
Yu Gao ◽  
Meiying Wu ◽  
Haiping Fan ◽  
Yongji Huang ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Pericentromeric Heterochromatin ◽  
Recombination Suppression ◽  
Origin And Evolution ◽  
Histone 3 ◽  
Telocentric Chromosomes ◽  
Mastacembelus Armatus ◽  
Major Target

AbstractCompartmentalization is one of the principles of chromosome 3D organization and has been suggested to be driven by the attraction of heterochromatin. The extent to which the pericentromeric heterochromatin (PCH) impacts chromosome compartmentalization is yet unclear. Here we produced a chromosome-level and fully phased diploid genome of an aquaculture fish, zig-zag eel (Mastacembelus armatus), and identified the centromeric and pericentromeric regions in the majority of chromosomes of both haploid genomes. The PCH is on average 4.2 Mb long, covering 17.7% of the chromosomes, and is the major target of histone 3 lysine 9 trimethylation (H3K9me3). In nearly half of the chromosomes, the PCH drives the chromosomes into two or three megascale chromatin domains with the PCH being a single one. We further demonstrate that PCH has a major impact in submetacentric, metacentric and small telocentric chromosomes in which the PCH drives the distribution of active and inactive compartments along the chromosomes. Additionally, we identified the young and homomorphic XY sex chromosomes that are submetacentric with the entire short-arm heterochromatinized. Interestingly, the sex-determining region seems to arise within the PCH that has been in place prior to the X-Y divergence and recombination suppression. Together, we demonstrate that the PCH can cover a considerably large portion of the chromosomes, and when it does so, it drives chromosome compartmentalization; and we propose a new model for the origin and evolution of homomorphic sex chromosomes in fish.

Linkage Studies between HL-A and GPT Polymorphisms and Other Genetic Markers

Vox Sanguinis ◽  
1976 ◽  
Vol 30 (1) ◽  
pp. 68-73 ◽  
Author(s):  
H. W. Goedde ◽  
D. Stender ◽  
K.-S. Saternus ◽  
Heide-G. Benkmann ◽  
Ch. Hiller ◽  
...  
Keyword(s):  
Genetic Markers ◽  
Linkage Studies

X-Linkage and Manic-Depressive Illness

1975 ◽  
Vol 127 (5) ◽  
pp. 482-488 ◽  
Author(s):  
Armand W. Loranger
Keyword(s):  
Genetic Markers ◽  
Depressive Illness ◽  
Linkage Studies ◽  
Review Of The Literature ◽  
Manic Depressive Illness ◽  
X Linkage ◽  
Manic Depressive ◽  
Affected Parent ◽  
Additional Support ◽  
General Explanation

SummaryThirty years ago it was suggested that the apparently higher incidence of manic-depressive illness in women might be due to X-linked heredity. The hypothesis was undermined by subsequent reports of the frequent occurrence of father to son transmission. Winokur and his associates recently revived it, providing data which indicated that such transmission is absent or rare in the bipolar form of the illness. Additional support has come from linkage studies with known genetic markers located on the X chromosome. The present study, based on the 400 parents of 100 male and 100 female bipolar manic-depressive probands, failed to discover a lack of father-son compared to other affected parent-child pairs. This finding, together with a review of the literature, would indicate that it is premature to invoke X-linked heredity as a general explanation for bipolar manic-depressive illness, though there is mounting evidence that it may account for the illness in some family pedigrees.

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