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At least 19 recordsLinked to original sources
PubMed1998

Unusual occurrence of a ZZ/ZW sex-chromosome system and supernumerary chromosomes in Characidium cf. fasciatum (Pisces, Characiformes, Characidiinae).

Individuals of two populations of the fish Characidium cf. fasciatum were cytogenetically studied and showed a basic diploid number of 50 chromosomes. Some fishes were found to have 51 to 54 chromosomes due to the presence of one to four small subtelocentric/acrocentric supernumerary chromosomes. When analyzed by conventional Giemsa staining, male and female specimens of C. cf. fasciatum from the Quinta stream and Pardo River presented the same basic karyotypic macro- and microstructure, consisting of 32 metacentric and 18 submetacentric chromosomes. Ag-NORs were terminally located on the long arms of two submetacentric chromosome pairs. Constitutive heterochromatin was identified by C-banding as small pericentromeric blocks in the majority of the chromosomes, and B-chromosomes were found to be heterochromatic. The occurrence of one totally heterochromatic submetacentric chromosome restricted to females and considered as an unusual feature in fish karyotypes led to the identification of a ZZ/ZW sex-chromosome system. The implications of chromosomic differentiation observed in the genus Characidium are discussed.

Journal Article↗
PubMed2001

Cytogenetics of collared lemmings (Dicrostonyx groenlandicus). II. Meiotic behavior of B chromosomes suggests a Y-chromosome origin of supernumerary chromosomes.

The patterns of synapsis and chiasma formation of the B chromosomes of male collared lemmings (Dicrostonyx groenlandicus) were analyzed by light and electron microscopy and compared to expectations for various hypotheses for the intragenomic origin of supernumerary chromosomes. Pachytene analysis revealed a variety of synaptic configurations including B-chromosome univalents, bivalents and trivalents. In approximately one-half of the pachytene nuclei examined, B chromosomes were in synaptic associations with the normally unpaired portion of the Y chromosome. The B-chromosome configurations at pachynema, including those involving the Y chromosome, were maintained into diakinesis and metaphase I. The meiotic behavior of the B chromosomes was inconsistent with their derivation from centric-fusion products, isochromosome formation, small-autosome polysomy, or the X chromosome. However, the frequent synapsis and apparent recombination between B chromosomes and the Y chromosome implicate this sex chromosome as a possible source of the B chromosomes in collared lemmings.

Animals↗
PubMed1987

Mosaic tetrasomy 12p: four new cases, and confirmation of the chromosomal origin of the supernumerary chromosome in one of the original Pallister-Mosaic syndrome cases.

Four new cases are reported in which mosaicism for a supernumerary chromosome interpreted as an isochromosome for 12p [i(12p)] is present. In 2 cases seen in early childhood the mosaicism was present at a low level in peripheral blood and was documented in one case to be present with a higher frequency in fibroblast cultures from skin. These cases have clinical features compatible with those in previously reported cases of the Teschler-Nicola/Killian syndrome, many of whom have now been found to be mosaic for a similar i(12p) chromosome in fibroblast cultures. One case was diagnosed prenatally from amniotic fluid culture. The fourth case was a neonatal death, in which fibroblast cultures were established from muscle and increased activity of LDH-B was demonstrated, supporting the theory that the origin of the additional chromosome was from 12p. Loss of the cell line with the supernumerary chromosome occurs after long-term fibroblast culture. Previously unpublished studies showing increased LDH-B activity in case 1 of Pallister-Mosaic syndrome originally reported in 1977 are also reported. It is of interest that our 2 cases which did not survive birth and one previously published case diagnosed prenatally had diaphragmatic herniae.

Abnormalities, Multiple↗
PubMed1999

Chromosomal polymorphisms due to supernumerary chromosomes and pericentric inversions in the eyelidless microteiid lizard Nothobachia ablephara (Squamata, Gymnophthalmidae).

Cytogenetic studies were performed on eight specimens of the monotypic microteiid lizard Nothobachia ablephara, endemic of the sand dunes of the middle São Francisco river, in the semiarid caatinga, State of Bahia, Brazil. Chromosomes from fibroblast cultures were analysed after conventional, Ag-NOR staining, C-, and replication R- banding. A basic karyotype of 2n = 62, consisting mostly of subtelocentric and acrocentric chromosomes of decreasing size, was found in five specimens. Diploid number variation (2n = 63 and 2n = 64) occurred in two specimens due to the presence of one and two medium-sized subtelocentric supernumerary chromosomes (Bs). The Bs were not clearly distinguishable from the autosomes in Giemsa-stained metaphases and C-banding, but showed late replication after R-banding. Polymorphisms of pairs 1 and 5, observed in three different combinations, including acrocentrics, subtelocentrics, submetacentrics and metacentrics, were interpreted as the result of small pericentric inversions. Variation in the number of Ag-NORs was also reported. A chromosomal mechanism of sex determination of the XX:XY type is present in this species. Our data add more evidence to confirm the remarkable chromosomal variability that has been found in Gymnophthalmidae.

Animals↗
PubMed1985

Supernumerary chromosomes in Drosophila nasuta albomicana.

Supernumerary chromosomes have been detected in the karyotype of D.n.albomicana. Their number varies from one to three. They are the smallest elements in the karyotype. Karyotypes of D.n.albomicana with and without supernumerary chromosomes have been presented.

Animals↗
PubMed1978

Chromosomal polymorphism caused by supernumerary chromosomes in Rattus rattus ssp. frugivurus (Rafinesque, 1814) (Rodentia, Muridae).

A chromosomal numeric polymorphism 2n = 38, 39, 40 and 41 in the species Rattus rattus ssp. frugivurus (Rafinesque, 1814) is reported for the first time for this subspecies. The numbers 2n = 39, 40 and 41 are new for the species. The polymorphism is due to the presence of 1, 2 or 3 B-chromosomes, which are all small metacentrics of the size and shaped vary close to the other autosomes of the normal complement, and whose character of being supernumeraries is shown in Meiosis.

Animals↗
PubMed1996

Is the Y chromosome of Drosophila an evolved supernumerary chromosome?

The Y chromosomes of most Drosophila species are necessary for male fertility but they are not involved in sex determination. They have many puzzling properties that resemble the effects caused by B chromosomes. Classical genetic and molecular studies reveal substantial affinities between Y and B chromosomes and suggest that the Y chromosomes of Drosophila are not degenerated homologues of the X chromosomes, but rather that their Y chromosomes evolved as specialized supernumeraries similar to classical B chromosomes.

Animals↗
PubMed1998

Supernumerary chromosomes in filamentous fungi.

Within a fungal species, a subset of individuals may have more than the minimal complement of chromosomes. If the extra chromosomes are composed primarily of DNA not found in all representatives of the species, they are most appropriately referred to as supernumerary chromosomes. The patterns of repeated DNA sequences on certain supernumerary chromosomes suggest that they have a different evolutionary history from the essential chromosomes in the same genome. Supernumerary chromosomes can carry functional genes and, in at least two fungal species, genes on such chromosomes play important roles in host-pathogen interactions. Supernumerary chromosomes that confer an adaptive advantage in certain habitats, such as the ability to cause disease on a specific host, may be referred to as "conditionally dispensable" chromosomes in order to reflect their importance in some, but not all, growth conditions. In addition to describing the structural and functional characteristics of known supernumerary chromosomes in fungi, this review discusses the relative merits of the terms that have been used to describe them, and establishes experimental criteria for their identification.

Chromosomes, Fungal↗
PubMed1992

Complementary duplication and deletion of 17 (pcen----p11.2): a family with a supernumerary chromosome comprised of an interstitially deleted segment.

A sister and brother were investigated because both were developmentally delayed although they had somewhat different physical anomalies. The girl was found to have an interstitial deletion of chromosome 17. Her karyotype was 46,XX,del(17) (pter----p11.2::cen----qter). Her brother had normal chromosomes in peripheral lymphocytes. Cytogenetic investigation of the mother showed the presence of the same deletion as in her daughter and a small supernumerary chromosome. The supernumerary chromosome appeared to contain the material deleted from the short arm of 17 since the mother's phenotype was normal. Study of skin fibroblasts in her son showed that he was mosaic for a normal cell line and one that contained the extra small chromosome; thus, he had mosaic partial trisomy 17(cen----p11.2). The origin of the centromere and telomere(s) of the small supernumerary chromosome in this family presents an interesting problem.

Centromere↗
PubMed1981

Supernumerary chromosomes and their possible origin in the karyotype of Indian bush rat, Golunda ellioti gujerati.

The incidence of supernumerary chromosomes has been frequently observed in one of the subspecies of Indian bush rat, Golunda ellioti gujerati Thomas 1923. Their number varied from 1 to 4 with consistent number of supernumeraries in each individual specimen. A possible explanation is given towards the origin of supernumerary chromosomes in Golunda ellioti gujerati. Two acrocentric chromosomes can give rise to a single large acrocentric and a supernumerary chromosome. This can happen by separation of centromere from one of the acrocentrics and translocation of the centric arms to the telomeric region of the second chromosomes, thus to form large acrocentric leaving the centromeric fragment as supernumerary chromosome.

Animals↗
PubMed1976

Chromosome organisation in the Australian plague locust, Chortoicetes terminifera. 1. Banding relationships of the normal and supernumerary chromosomes.

In Chortoicetes terminifera, G-banding, produced by the trypsin treatment of air-dried slides followed by Giemsa staining, leads to light staining gaps at the secondary constrictions on autosomal pair 6 and regions proximal to the centromere on the long arms of pair 4. The variable short arms of two of the three smallest pairs were usually flared and lightly stained after treatment. In contrast to the relatively minor response of the normal chromosome set to G-banding, the large supernumerary chromosomes of C. terminifera show a spectacular series of dark bands alternating with lightly stained gaps. Two G-band variants of the B-chromosome were found in a laboratory stock. These patterns of G-banding are discernable both at mitosis in adults and embryos of both sexes and at all stages of male meiosis. Some regions which are gaps after G-banding appear as dark bands after C-banding. Consequently the supernumerary chromosome is mainly darkly stained with C-banding. In addition the centromeres and some telomeres are C-banded along with narrow interstitial bands and polymorphic heterochromatic blocks.--C-banding was not always successful, the technique often yields a mixture of G- and C-banding. The disparity of banding between the normal complement and the B-chromosome implies that whatever the source of origin of the B it has undergone spectacular changes in organisation since its origin.

Animals↗
PubMed1977

Supernumerary chromosomes in the black rat (Rattus rattus) and their distribution in three geographic variants.

Supernumerary chromosomes have been examined in 352 black rats, covering three geographic variants, by use of conventional and C-band staining techniques. Metacentric supernumerary chromosomes, one to three in number, were found in Malayan black rats (Rattus rattus diardii), with 2n=42, in Indian black rats (R. rattus rufescens), with 2n=38, and in Ceylonese black rats (R. rattus kandianus), with 2n=40. The supernumeraries had similar morphology and stained heavily along their entire length by C-band staining. These findings suggested that the supernumeraries had originally developed in the Asian-type black rats and then were sequentially transmitted to the Ceylonese and Oceanian-type black rats, probably in southwestern Asia. A subtelocentric supernumerary chromosome found in one Japanese black rat seemed to have developed independently from the above metacentric supernumeraries.

Animals↗
PubMed1980

The ring nature of a tiny supernumerary chromosome fragment.

We report a 5 1/2-year-old girl with a tiny supernumerary chromosome fragment found in mosaic. The ring nature of the tiny fragment was demonstrated by the detection of the characteristic products of a ring chromosome. The clinical consequence of a ring chromosome and the impact of finding a supernumerary chromosome fragment, especially in the practice of prenatal chromosome diagnosis, are discussed.

Child, Preschool↗
PubMed1995

Absence of lambda immunoglobulin sequences on the supernumerary chromosome of the "cat eye" syndrome.

The supernumerary bisatellited chromosome causing the "cat eye" syndrome (CES) is of chromosome 22 origin and consists of an inverted duplication of the 22pter-->22q11.2 region. To determine the extent of involvement of band q11.2 on the bisatellited chromosome, copy number assessment of sequences homologous to cloned lambda immunoglobulin (lambda Ig) gene region probes was carried out on DNA from individuals with CES using densitometric analysis of Southern blots. None of the 10 lambda Ig sequences studied was found in increased copy number in DNA from any of the 10 CES individuals tested, indicating that these sequences are not present on the supernumerary chromosome. The breakpoints involved in the generation of the bisatellited supernumerary chromosome associated with CES are therefore proximal to the lambda Ig gene region.

Anal Canal↗
PubMed1960

Effects of supernumerary chromosomes on production of pigment in Haplopappus gracilis.

One of the two types of supernumerary chromosomes found in Haplopappus gracilis effects pigment production in the achene walls. When one, two, and four supernumerary chromosomes were added to the basic complement, a corresponding increase in the amount of one type of pigment was found to occur. No overlapping of the effects on pigment production was observed among different numbers of supernumeraries or between the supernumeraries and normal chromosome complement.

Chromosomes↗