Chromosomal rearrangements in rock wallabies, Petrogale (Marsupialia: Macropodidae). II. G-banding analysis of Petrogale godmani

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 935-940 ◽  
Author(s):  
M. D. B. Eldridge ◽  
P. G. Johnston ◽  
R. L. Close ◽  
P. S. Lowry

Chromosomal rearrangements in the two currently recognised races of Petrogale godmani were examined using C- and G-banding. The nominate race P. godmani godmani (2n = 20) was found to possess an inverted chromosome 5 and an acrocentric 6–10 fusion, which can be derived from a 6–10 centric fusion by a centromeric transposition. The Cape York race (2n = 22) was found to retain the ancestral submetacentric chromosome 4 and the ancestral chromosome 5. Thus despite their genie similarity, the two races clearly have major chromosomal differences and should be regarded as separate species. Petrogale g. godmani shares two derived chromosomes with another Queensland taxon, the assimilis race of P. assimilis, indicating recent common ancestry. The Cape York race retains characteristics of an ancestral stock of Petrogale and its genic similarity with P. g. godmani could therefore be the result of extensive introgression.Key words: chromosomal rearrangements, G-banding, Marsupialia, Petrogale.

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 798-802 ◽  
Author(s):  
M. D. B. Eldridge ◽  
R. L. Close ◽  
P. G. Johnston

The karyotypes of Petrogale inornata and the two currently recognised races of Petrogale penicillata were examined using G-banding from cultured fibroblasts. Petrogale inornata (2n = 22) was found to retain plesiomorphic chromosomes 3 and 4 but possessed an apomorphic inverted chromosome 5 (5i). This 5i appears identical with the 5i found in two other Queensland taxa, Petrogale assimilis and Petrogale godmani, and can be derived from the ancestral chromosome 5 by an extensive paracentric inversion or a centromeric transposition. Petrogale penicillata penicillata (2n = 22) and Petrogale penicillata herberti (2n = 22) both possess the synapomorphic acrocentric chromosome 3, which appears to differ from the plesiomorphic 3 by a small centromeric transposition. Petrogale p. penicillata was also found to be characterised by an apomorphic acrocentric chromosome 4, while P. p. herberti was characterised by an autapomorphic submetacentric chromosome 4. Both apomorphic chromosomes 4 can be related to the plesiomorphic chromosome 4 by centromeric transpositions. Thus although P. inornata is chromosomally distinct it is more closely related to other north Queensland taxa than it is to either P. p. penicillata or P. p. herberti.Key words: chromosomal rearrangements, G-banding, Marsupialia, Petrogale, Macropodidae.


Genome ◽  
2003 ◽  
Vol 46 (2) ◽  
pp. 291-303 ◽  
Author(s):  
I A.P Parkin ◽  
A G Sharpe ◽  
D J Lydiate

The progenitor diploid genomes (A and C) of the amphidiploid Brassica napus are extensively duplicated with 73% of genomic clones detecting two or more duplicate sequences within each of the diploid genomes. This comprehensive duplication of loci is to be expected in a species that has evolved through a polyploid ancestor. The majority of the duplicate loci within each of the diploid genomes were found in distinct linkage groups as collinear blocks of linked loci, some of which had undergone a variety of rearrangements subsequent to duplication, including inversions and translocations. A number of identical rearrangements were observed in the two diploid genomes, suggesting they had occurred before the divergence of the two species. A number of linkage groups displayed an organization consistent with centric fusion and (or) fission, suggesting this mechanism may have played a role in the evolution of Brassica genomes. For almost every genetically mapped locus detected in the A genome a homologous locus was found in the C genome; the collinear arrangement of these homologous markers allowed the primary regions of homoeology between the two genomes to be identified. At least 16 gross chromosomal rearrangements differentiated the two diploid genomes during their divergence from a common ancestor.Key words: genome evolution, Brassicaeae, polyploidy, homoeologous linkage groups.


Development ◽  
1996 ◽  
Vol 122 (8) ◽  
pp. 2395-2403 ◽  
Author(s):  
B. Grbic ◽  
A.B. Bleecker

In this paper, we describe a late-flowering ecotype of Arabidopsis, Sy-0, in which the axillary meristems maintain a prolonged vegetative phase, even though the primary shoot apical meristem has already converted to reproductive development. This novel heterochronic shift in the development of axillary meristems results in the formation of aerial rosettes of leaves at the nodes of the primary shoot axis. We present evidence that the aerial-rosette phenotype arises due to the interaction between dominant alleles of two genes: ART, aerial rosette gene (on chromosome 5) and EAR, enhancer of aerial rosette (on chromosome 4): EAR has been tentatively identified as a new allele of the FRI locus. The possible role of these two genes in the conversion of shoot apical meristems to reproductive development is discussed.


2020 ◽  
Author(s):  
Jingbo Zhang ◽  
Bei Zhang ◽  
Tong Liu ◽  
Huihui Xie ◽  
Jingfang Zhai

Abstract Background: Carriers of balanced reciprocal chromosomal translocations are at known reproductive risk for offspring with unbalanced genotypes and resultantly abnormal phenotypes. Once fertilization of a balanced translocation gamete with a normal gamete, the partial monomer or partial trisomy embryo will undergo abortion, fetal arrest or fetal malformations. We reported a woman with chromosomal balanced translocation who had two adverse pregnancies. Prenatal diagnosis was made for her third pregnancy to provide genetic counseling and guide her fertility. Case presentation: We presented a woman with chromosomal balanced translocation who had three adverse pregnancies. Routine G banding and CNV-seq were used to analyze the chromosome karyotypes and copy number variants of amniotic fluid cells and peripheral blood. The karyotype of the woman was 46,XX,t(4;5)(q33;p15). During her first pregnancy, odinopoeia was performed due to fetal edema and abdominal fluid. The umbilical cord tissue of the fetus was examined by CNV-seq. The results showed a genomic gain of 24.18 Mb at 4q32.3-q35.2 and a genomic deletion of 10.84 Mb at 5p15.33-p15.2 and 2.36 Mb at 15q11.1-q11.2. During her second pregnancy, she did not receive a prenatal diagnosis because a routine prenatal ultrasound examination found no abnormalities. In 2016, she gave birth to a boy.. The karyotype the of the boy was 46,XY,der(5)t(4;5)(q33;p15)mat. The results of CNV-seq showed a deletion of short arm of chromosome 5 capturing regions 5p15.33p15.2, a copy gain of the distal region of chromosome 4 at segment 4q32.3q35.2, a duplication of chromosome 1 at segment 1q41q42.11 and a duplication of chromosome 17 at segment 17p12. During her third pregnancy, she underwent amniocentesis at 17 weeks of gestation. Chromosome karyotype hinted 46,XY,der(5)t(4;5)(q33;p15)mat. Results of CNV-seq showed a deletion of short arm (p) of chromosome 5 at the segment 5p15.33p15.2 and a duplication of the distal region of chromosome 4 at segment 4q32.3q35.2.Conclusions: Chromosomal abnormalities in three pregnancies were inherited from the mother. Preimplantation genetic diagnosis is recommended to prevent the birth of children with chromosomal abnormalities.


1998 ◽  
Vol 78 (4) ◽  
pp. 1113-1126 ◽  
Author(s):  
D.R. Dixon ◽  
P.L. Pascoe ◽  
L.R.J. Dixon

Consistent with most other closely-related polychaete species which have been analysed cytogenetically to-date, Pomatoceros triqueter and P. lamarckii share an identical chromosome number (2n=24) and have a number of other karyotypic features in common. However, commensurate with their separate species status, their karyotypes differ at least in four chromosome positions as a result of structural chromosomal rearrangements. With a rDNA probe using the FISH technique, we have been able to demonstrate that the nucleolar organizer region (NOR) occurs at the same site on the same pair of chromosomes in the two species, which indicates that an inversion event is unlikely to have been the cause of the species variation in this particular case. Taken together, these karyotypic differences may be indicative of a chromosomal barrier to the formation of fertile offspring; an important feature for maintaining species integrity where the two forms occur sympatrically, such as in parts of south-west England.


2021 ◽  
Author(s):  
Taccyanna Mikulski Ali ◽  
Emilia Mateu-Brull ◽  
Nuria Balaguer ◽  
Camila Dantas de Souza ◽  
Haline Risso Borges ◽  
...  

Abstract BackgroundSince 2011, screening maternal blood for cell-free foetal DNA (cffDNA) fragments has offered a robust clinical tool to classify pregnancy as low or high-risk for Down, Edwards, and Patau syndromes. With recent advances in molecular biology and improvements in data analysis algorithms, the screening’s scope of analysis continues to expand. Indeed, screening now encompassess additional conditions, including aneuploidies for sex chromosomes, microdeletions and microduplications, rare autosomal trisomies, and, more recently, segmental deletions and duplications called copy number variations (CNVs). Yet, the ability to detect CNVs creates a new challenge for cffDNA analysis in couples in which one member carries a structural rearrangement such as a translocation or inversion.Case presentationWe report a segmental duplication of the long arm of chromosome 3 and a segmental deletion of the short arm of chromosome 5 detected by cffDNA analysis in a 25-year-old pregnant woman. G-band karyotyping in amniotic fluid only detected an abnormality in chromosome 5. Next-generation sequencing in amniocytes confirmed both abnormalities and identified breakpoints in 3q26.32q29 and 5p13.3p15. The foetus died at 21 weeks of gestation due to multiple abnormalities, and later G-band karyotyping in the parents revealed that the father was a carrier of a balanced reciprocal translocation [46,XY,t(3;5)(q26.2;p13)]. Maternal karyotype appeared normal.ConclusionThis case provides evidence that extended cffDNA can detect, in addition to aneuploidies for whole chromosomes, large segmental aneuploidies. In some cases, this may indicate the presence of chromosomal rearrangements in a parent. Such abnormalities are outside the scope of standard cffDNA analysis targeting chromosomes 13, 18, 21, X, and Y, potentially leading to undiagnosed congenital conditions.


1975 ◽  
Vol 23 (2) ◽  
pp. 293 ◽  
Author(s):  
PR Baverstock ◽  
CHS Watts ◽  
JT Hogarth

Although R. villosissimus and R. sordidus have been considered to be conspecific, they differ karyotypically in at least 11 chromosomal rearrangements. It seems likely that they diverged early in the evolution of Rattus, and they should be regarded as separate species.


Author(s):  
Lodovico Galleni ◽  
Ileana Puccinelli

A karyometric analysis of the diploid complement of two species of the genus Procerodes (Tricladida: Maricola), both from British waters, has been carried outThe diploid number of Procerodes littoralis, 2n = 14, was established on mitosis from regenerative blastema and the haploid number n = 7 from spermatocyte I stages. All the chromosomes are metacentric, their centromeric index varying from 47·91 in the chromosome 5 to 38·39 in the chromosome 4.


1992 ◽  
Vol 40 (6) ◽  
pp. 605 ◽  
Author(s):  
MDB Eldridge ◽  
RL Close

The taxonomy of Petrogale has been in a state of flux for many years. The eight chromosome races of the eastern Petrogale radiation are currently placed in four species. However, several of these 'species' contain chromosomally unrelated taxa. In this paper a species definition for Petrogale is proposed that allows for some gene flow between species but requires a species to maintain a substantial and distinct genetic identity. When this definition was applied to the eastern Petrogale eight 'good' species were identified. Thus we now consider the eastern Petrogale complex to consist of P. penicillata, P. herberti (formerly P. penicillata herberti), P. inornata, P. assimilis, P. sharmani, sp. nov. (formerly the Mt Claro race), P. mareeba, sp. nov. (formerly the Mareeba race), P. godmani and P. coenensis, sp. nov. (formerly the Cape York race). Several of these taxa are cryptic species and the primary means of identification used was chromosome number and morphology. However, genic data were useful in establishing whether each taxon should be regarded as a separate species.


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