Heterologous Synapsis and Crossover Suppression in Heterozygotes for a Pericentric Inversion in the Zebra Finch

2015 ◽  
Vol 147 (2-3) ◽  
pp. 154-160 ◽  
Author(s):  
Lucía del Priore ◽  
María I. Pigozzi
Keyword(s):  
Zebra Finch ◽  
Pericentric Inversion ◽  
Crossing Over ◽  
Complete Suppression ◽  
Chromosome 6 ◽  
Karyotypic Evolution ◽  
Male And Female ◽  
Synaptonemal Complexes ◽  
Pericentric Inversions ◽  
Mlh1 Foci

In the zebra finch, 2 alternative morphs regarding centromere position were described for chromosome 6. This polymorphism was interpreted to be the result of a pericentric inversion, but other causes of the centromere repositioning were not ruled out. We used immunofluorescence localization to examine the distribution of MLH1 foci on synaptonemal complexes to test the prediction that pericentric inversions cause synaptic irregularities and/or crossover suppression in heterozygotes. We found complete suppression of crossing over in the region involved in the rearrangement in male and female heterozygotes. In contrast, the same region showed high levels of crossing over in homozygotes for the acrocentric form of this chromosome. No inversion loops or synaptic irregularities were detected along bivalent 6 in heterozygotes suggesting that heterologous pairing is achieved during zygotene or early pachytene. Altogether these findings strongly indicate that the polymorphic chromosome 6 originated by a pericentric inversion. Since inversions are common rearrangements in karyotypic evolution in birds, it seems likely that early heterologous pairing could help to fix these rearrangements, preventing crossing overs in heterozygotes and their deleterious effects on fertility.

Diversity and Karyotypic Evolution in the Genus Neacomys (Rodentia, Sigmodontinae)

2015 ◽  
Vol 146 (4) ◽  
pp. 296-305 ◽  
Author(s):  
Willam O. da Silva ◽  
Julio C. Pieczarka ◽  
Rogério V. Rossi ◽  
Horacio Schneider ◽  
Iracilda Sampaio ◽  
...  
Keyword(s):  
Molecular Phylogeny ◽  
Diploid Number ◽  
Constitutive Heterochromatin ◽  
Chromosomal Evolution ◽  
The Other ◽  
Karyotypic Evolution ◽  
Drastic Reduction ◽  
Ancestral Species ◽  
Pericentric Inversions ◽  
Amazonian Region

Neacomys (Sigmodontinae) comprises 8 species mainly found in the Amazonian region. We describe 5 new karyotypes from Brazilian Amazonia: 2 cytotypes for N. paracou (2n = 56/FNa = 62-66), 1 for N. dubosti (2n = 64/FNa = 68), and 2 for Neacomys sp. (2n = 58/FNa = 64-70), with differences in the 18S rDNA. Telomeric probes did not show ITS. We provide a phylogeny using Cytb, and the analysis suggests that 2n = 56 with a high FNa is ancestral for the genus, as found in N. paracou, being retained by the ancestral forms of the other species, with an increase in 2n occurring independently in N. spinosus and N. dubosti. Alternatively, an increase in 2n may have occurred in the ancestral taxon of the other species, followed by independent 2n-reduction events in Neacomys sp. and in the ancestral species of N. tenuipes, N. guianae, N. musseri, and N. minutus. Finally, a drastic reduction event in the diploid number occurred in the ancestral species of N. musseri and N. minutus which exhibit the lowest 2n of the genus. The karyotypic variations found in both intra- and interspecific samples, associated with the molecular phylogeny, suggest a chromosomal evolution with amplification/deletion of constitutive heterochromatin and rearrangements including fusions, fissions, and pericentric inversions.

Unique phenotype associated with a pericentric inversion of chromosome 6 in three generations

1991 ◽  
Vol 39 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Katharine D. Wenstrom ◽  
Ann C. Muilenburg ◽  
Shivanand R. Patil ◽  
James W. Hanson
Keyword(s):  
Pericentric Inversion ◽  
Chromosome 6 ◽  
Three Generations

Karyotypic evolution in acute myelomonocytic leukemia with pericentric inversion of chromosome 16

1987 ◽  
Vol 24 (2) ◽  
pp. 257-262 ◽  
Author(s):  
Masafumi Taniwaki ◽  
Johji Inazawa ◽  
Shigeo Horiike ◽  
Shinichi Misawa ◽  
Tatsuo Abe ◽  
...  
Keyword(s):  
Pericentric Inversion ◽  
Karyotypic Evolution ◽  
Chromosome 16 ◽  
Acute Myelomonocytic Leukemia ◽  
Myelomonocytic Leukemia

scholarly journals Rieger's syndrome with pericentric inversion of chromosome 6.

1979 ◽  
Vol 63 (1) ◽  
pp. 40-44 ◽  
Author(s):  
M H Heinemann ◽  
R Breg ◽  
E Cotlier
Keyword(s):  
Pericentric Inversion ◽  
Chromosome 6

Acute myeloblastic leukemia with a pericentric inversion of chromosome 6 in a child with down syndrome

1994 ◽  
Vol 73 (2) ◽  
pp. 157-160 ◽  
Author(s):  
Sofia Shekhter-Levin ◽  
Joseph Mirro ◽  
Lila Penchansky ◽  
Maureen E. Sherer ◽  
Niel Wald ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Pericentric Inversion ◽  
Acute Myeloblastic Leukemia ◽  
Chromosome 6

CROSSING OVER IN A DOUBLE TRANSLOCATION IN DROSOPHILA

1972 ◽  
Vol 14 (1) ◽  
pp. 129-137 ◽  
Author(s):  
A. S. Robinson ◽  
C. F. Curtis
Keyword(s):  
Drosophila Melanogaster ◽  
Pest Control ◽  
The Other ◽  
Crossing Over ◽  
Male And Female ◽  
Differential Segment ◽  
Translocation Heterozygote

The production and fertility of a double translocation heterozygote in Drosophila melanogaster are reported. A difference in the fertility of male and female double heterozygotes was recorded and explained on the basis of crossing over, occurring in the differential segments of female double heterozygotes, producing extra unbalanced gametes. It was shown that crossing over was absent from one differential segment but the amount of crossing over occurring in the other differential segment was measured. The possible use of multiple translocation systems for pest control is discussed with particular reference to the use of double translocation heterozygotes.

scholarly journals Lack of underdominance in a naturally occurring pericentric inversion in Drosophila melanogaster and its implications for chromosome evolution.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 791-802
Author(s):  
J A Coyne ◽  
S Aulard ◽  
A Berry
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Genetic Drift ◽  
Related Species ◽  
Pericentric Inversion ◽  
Chromosome Evolution ◽  
Natural Populations ◽  
Crossing Over ◽  
Closely Related Species ◽  
Naturally Occurring

Abstract In(2LR)PL is a large pericentric inversion polymorphic in populations of Drosophila melanogaster on two Indian Ocean islands. This polymorphism is puzzling: because crossing over in female heterokaryotypes produces inviable zygotes, such inversions are thought to be underdominant and should be quickly eliminated from populations. The observed fixation for such inversions among related species has led to the idea that genetic drift can cause chromosome evolution in opposition to natural selection. We found, however, that In(2LR)PL is not underdominant for fertility, as heterokaryotypic females produce perfectly viable eggs. Genetic analysis shows that the lack of underdominance results from the nearly complete absence of crossing over in the inverted region. This phenomenon is probably caused by mechanical and not genetic factors, because crossing over is not suppressed in In(2LR)PL homokaryotypes. Our observations do not support the idea that the fixation of pericentric inversions among closely related species implies the action of genetic drift overcoming strong natural selection in very small populations. If chromosome arrangements vary in their underdominance, it is those with the least disadvantage as heterozygotes, like In(2LR)PL, that will be polymorphic or fixed in natural populations.

scholarly journals THE MANIFESTATION OF CHROMOSOME REARRANGEMENTS IN UNORDERED ASCI OF NEUROSPORA

Genetics ◽  
1974 ◽  
Vol 77 (3) ◽  
pp. 459-489
Author(s):  
David D Perkins
Keyword(s):  
Reciprocal Translocation ◽  
Chromosome Aberrations ◽  
Visual Inspection ◽  
Break Point ◽  
Crossing Over ◽  
Reciprocal Translocations ◽  
Analytical Technique ◽  
Large Numbers ◽  
Pericentric Inversions ◽  
Break Points

ABSTRACT Rapid, effective techniques have been developed for detecting and characterizing chromosome aberrations in Neurospora by visual inspection of ascospores and asci. Rearrangements that are detectable by the presence of deficient, nonblack ascospores in test crosses make up 5 to 10% of survivors after UV doses giving 10-55% survival. Over 135 rearrangements have been diagnosed by classifying unordered asci according to numbers of defective spores. (These include 15 originally identified or analyzed by other workers.) About 100 reciprocal translocations (RT's) have been confirmed and mapped genetically, involving all combinations of the seven chromosomes. Thirty-three other rearrangements generate viable nontandem duplications in meiosis. These consist of insertional translocations (IT's) (15 confirmed), and of rearrangements that involve a chromosome tip (10 translocations and 3 pericentric inversions). No inversion has been found that does not include the centromere. A reciprocal translocation was found within one population in nature. When pairs of RT's that involve the same two chromosome arms were intercrossed, viable duplications were produced if the breakpoints overlapped in such a way that pairing resembled that of insertional translocations (27 combinations).—The rapid analytical technique depends on the following. Deficiency ascospores are usually nonblack (W: "white") and inviable, while nondeficient ascospores, even those that include duplications, are black (B) and viable. Thus RT's typically produce 50% black spores, and IT's 75% black. Asci are shot spontaneously from ripe perithecia, and can be collected in large numbers as groups of eight ascospores representing unordered tetrads, which fall into five classes: 8B:0W; 6B:2W, 4B:4W, 2B:6B, 0B:8W. In isosequential crosses, 90-95% of tetrads are 8:0. When a rearrangement is heterozygous, the frequencies of tetrad classes are diagnostic of the type of rearrangement, and provide information also on the positions of break points. With RT's, 8:0 (alternate centromere segregation) = 0:8 (adjacent-1), 4:4's require interstitial crossing over in a centromere-break point interval, and no 6:2's or 2:6's are expected. With IT's, duplications are viable, 8:0 = 4:4, 6:2's are from interstitial crossing over, 0:8's or 2:6's are rare. Tetrads from RT's that involve a chromosome tip resemble those from IT's, as do tetrads from intercrosses between partially overlapping RT's that involve identical chromosome arms.—Because viable duplications and other aneuploid derivatives regularly occur among the offspring of rearrangements such as insertional translocations, care must be taken in selecting stocks, and original strains should be kept for reference.

scholarly journals High-capacity auditory memory for vocal communication in a social songbird

2020 ◽  
Vol 6 (46) ◽  
pp. eabe0440
Author(s):  
K. Yu ◽  
W. E. Wood ◽  
F. E. Theunissen
Keyword(s):  
Zebra Finch ◽  
Vocal Communication ◽  
High Capacity ◽  
Memory Capacity ◽  
Auditory Memory ◽  
Male And Female ◽  
Social Species ◽  
Nonhuman Animals ◽  
The Individual ◽  
Conditioning Experiments

Effective vocal communication often requires the listener to recognize the identity of a vocalizer, and this recognition is dependent on the listener’s ability to form auditory memories. We tested the memory capacity of a social songbird, the zebra finch, for vocalizer identities using conditioning experiments and found that male and female zebra finches can remember a large number of vocalizers (mean, 42) based solely on the individual signatures found in their songs and distance calls. These memories were formed within a few trials, were generalized to previously unheard renditions, and were maintained for up to a month. A fast and high-capacity auditory memory for vocalizer identity has not been demonstrated previously in any nonhuman animals and is an important component of vocal communication in social species.

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