Extra Acrocentric Chromosome Research Articles

Molecular and cytological characterization of an extra acrocentric chromosome that restores male fertility of wheat in the msH1 CMS system

A new CMS system designated as 'msH1' has been reported in bread wheat using the cytoplasm of H. chilense. While testing this system in different wheat backgrounds, a highly fertile line with chromosome number 42 plus an extra acrocentric chromosome was obtained. The extra chromosome did not pair with any wheat chromosome at meiosis, and progeny from this line which lack the acrocentric chromosome showed pollen abortion and male sterility. In order to establish the origin of this chromosome, FISH using H. chilense genomic DNA as probe was used and showed that it had originated from H. chilense chromosome(s). The novel chromosome did not possess sequences similar to wheat rDNA; however, the probe pSc119.2 from S. cereale containing the 120bp family was found to occur at the end of its long arm. Data obtained from FISH and EST molecular markers confirm that the long arm of the acrocentric chromosome is indeed, the short arm of chromosome 1H(ch) from H. chilense. We suggest that the novel chromosome originated from a deletion of the distal part of the long arm of chromosome 1H(ch). Neither the 1H(ch)S short arm, nor the whole chromosome 1H(ch) restores pollen fertility of the alloplasmic wheat. Therefore, the restorer gene on the acrocentric chromosome must be located on the retained segment from the hypothetical 1H(ch)L, while some pollen fertility inhibitor could be present on the deleted 1H(ch)L distal segment. Disomic addition of the acrocentric chromosome was obtained and this line resulted fully stable and fertile.

A Novel Robertsonian Translocation [57,rob(1/29)(4/28)] and Polymorphism of Nucleolar Organizer Regions (NORs) of Captive Thai Banteng (Bos javanicus birmanicus)

Robertsonian translocation (centric fusion) has been well documented in domestic cattle, with the most commonly occurring fusion involving chromosomes 1 and 29. Fifty conventional staining, G-banding, C-banding and NOR-banding metaphase spreads derived from lymphocyte cultures were analyzed for each animal. The Thai banteng has diploid chromosome number of 2n=57 in males and females instead of the normal 2n=60. The chromosomes presence of an extra acrocentric chromosome and 2 submetacentric chromosome while the loss of 6 telocentric chromosomes was observed [57, rob(1/29)(4/28)]. Results from G-banding analysis confirm that 6 autosomes involved in the translocation are bovine homologues 1/29 and 4/28. This is the first report on polymorphism of nucleolar organizer regions (NORs) of Thai banteng. It indicated the presence of heteromorphism of telocentric chromosomes in both male and female, there are NORs in 1 telocentric chromosome but it dose not exist in another telocentric chromosome.

Description of a ZZ/ZW sex chromosome system in Thoracocharax cf. stellatus (Teleostei, Characiformes, Gasteropelecidae)

The family Gasteropelecidae is composed of three genera and eight species. This study shows that Thoracocharax cf. stellatus has 2n = 52 chromosomes for both sexes. The five males studied showed 8 metacentric, 16 submetacentric, 4 subtelocentric, and 24 acrocentric chromosomes; the seven females showed only one submetacentric chromosome, belonging to pair 11, and one extra acrocentric chromosome, smaller than all the other chromosomes, characterizing the presence of a ZZ/ZW sex chromosome system in this species. Nucleolus organizing regions (NORs) were detected on the short arms of the subtelocentric chromosome pair 13. Constitutive heterochromatin was identified at pericentromeric and terminal positions in almost all chromosomes. The W chromosome was almost entirely heterochromatic, except for a small terminal euchromatic segment. The analyses of the amount of nuclear DNA found 2.18 ± 0.09 pg of DNA per diploid nucleus, without significant differences between sexes. A discussion about the evolution of the sex chromosomes in this group is presented.

Development of Monotelosomic and Monoacrosomic Alien Addition Lines in Rice (Oryza sativa L.) Carrying a Single Chromosome of 0. punctata Kotschy.

Three monotelosomic alien addition lines (MtAALs:2n=2x+1t) and one monoacrosomic alien addition line (MaAAL:2n=2x+1a) of japonica rice cultivar Nippon-bare, each carrying a single chromosome of a diploid strain of O. punctata (W1514) were isolated from the progenies of respective monosomic alien addition lines (MAAL:2n=2x+1) for chromosomes 2, 4, 7 and 9 of O. punctata. Among them, three were classified as MtAALs carrying extra telocentric chromosomes 2 and 7, and an extra short arm of chromosome 9 in addition to the diploid complement based on the mitotic and meiotic chromosome analysis. The remaining one was similarly classified as a MaAAL carrying an extra acrocentric chromosome consisting of a complete short arm and a heterochromatic proximal region of the long arm of chromosome 4. Three MtAALs were designated as MtAALs 2, 7, and 9S (short arm of chromosome 9), respectively and one MaAAL was designated as MaAAL 4S4L. Their morphology, seed fertility and the transmission rates of the extra chromosome were compared with those of the respective primary trisomics and MAALs. The plant morphology of MtAAL 2 and MaAAL 4S4L was similar to that of the respective MAALs, while the plant morphology of MtAAL 9S was similar to that of the disomics. The plant morphology of MtAAL 7 was similar to that of the secondary trisomics for the short arm of chromosome 7. The seed fertility was higher than that of the respective MAALs, suggesting that the addition lines carrying a small chromosome fragment such as telosome or acrosome could give rise to functional gametes. The transmission rates of the extra chromosome were similar to those of the respective MAALs. Most of the PMCs in the MtAALS and the MaAAL showed a 12II + 1I (telosome or acrosome) configuration at the diakinesis and first metaphase. These facts suggest that the extra telocentric or acrocentric chromosomes originated from a misdivision of an alien univalent at anaphase I or anaphaseII of the respective MAALs and the following chromosome breakage.

Acrotrisomic analysis in linkage mapping in barley (Hordeum vulgare L.)

Three acrotrisomic lines, Triplo IL(1S), 3L(3S), and 4L(4S), each carrying an extra acrocentric chromosome, were used for cytogenetic linkage mapping of barley chromosomes. The cytological structures of the acrocentric chromosome of the three acrotrisomic lines were studied with an improved Giemsa N-banding technique. The long (1L) and short arm (1S) of chromosome 1 had deficiencies of approximately 38% and 65%, respectively. The percentages of deficiencies were 0 and 77.8% for 3L and 3S, and 31.7 and 59.3% for 4L and 4S, respectively. All three genes tested (br, f c , gs3) in 1S and all three genes tested, f8, n and 1k2 in 1L showed a disomic ratio indicating that they are located in the deficient segments. Two genes (a c , yst2) located in the middle segment of 3S in linkage map showed a trisomic ratio, and two others a n , x s showed a disomic ratio. The only gene(f9) tested in 4L showed a trisomic ratio. Two genes (1g4, g1) located in the proximal segment of 4S in the linkage map showed a trisomic ratio, whereas two genes (br2, g13) located distally in 4S showed a disomic ratio, indicating that the breakage occurred between g1 and br2. This experiment demonstrates a new method for physical localization of genes on chromosome segments in material such as barley in which pachytene analysis can not be effectively used for accurate determination of break points in structural changes. Problems associated with this new technique are discussed.

Benefits derived from the cytogenetic analysis of childhood tumours

Cytogenetic analysis was made on 27 children attending the Oncology Clinic during 1979. Of these 60% had acute lymphoblastic leukaemia (ALL) and 40% had solid tumours. Four children with ALL had chromosomal anomalies, three of these being noted at diagnosis. 1. A girl whose leukaemic clone had an XO karyotype -this was proliferating in the bone marrow at diagnosis. quiescent during remission, but released leukaemic cells into the periphery after a viral infection. This marker may allow early diagnosis of relapses. 2. A break in a ‘C’ chromosome in an isolated cell. 3. An unbandable extra acrocentric chromosome, like the short arm of an ‘E’. 4. A child finishing maintenance therapy has a translocation, i.e. 46XYt (2:9). Anomalies amongst solid tumours were less common. Three children with neuroblastoma, 2 with rhabdomyosarcoma, and 3 with non-Hodgkins lymphoma were normal. Of these, the child with the Burkitťs lymphoma benefited by being able to exclude the 8:14 translocation subgroup with the poorer prognosis. One of the 2 children with Wilms’ tumour-had a 3:8 balanced translocation which shall be traced through the family should other members develop tumours. Guidelines offering maximum return, suggest the benefit of cytogenetic analysis for: 1. ALL at diagnosis. 2. Burkitťs lymphoma. 3. Wilms’ tumour family studies.

Reproductive efficiency in aged female rabbits given supplemental progesterone and oestradiol.

Summary. The reproductive efficiency of twenty-eight aged does, 49 to 72 months old, was compared with that of eighteen young does, 6 to 13 months old. Fertilization rate and development in vitro of fertilized ova from rabbits induced to superovulate were not influenced by the doe's age. Ovulation rates following natural mating were only slightly reduced with age. However, the number of embryos per doe was much greater in young than in old does at 12 and 24 days post coitum. All young does had viable embryos, whereas the percentages of aged does with detectable implantation sites and viable embryos were 80 and 40, respectively, at 12 days post coitum, and 77 and 44 at 24 days post coitum. Aged female rabbits were given supplemental exogenous progesterone and/or oestradiol benzoate in an effort to increase reproductive efficiency. Progesterone treatment had no effect on the total number of young kindled but did prolong the gestation period, increase the birth weight and result in fewer live young kindled/doe. When administered on Days 3 to 29 of pregnancy, 4 μg/day of oestradiol alone or in combination with 2 and 4 mg progesterone completely blocked pregnancy in all does. Starting on Day 5 of pregnancy, oestradiol levels of 1 μg/day, with or without progesterone, had no effect. Chromosomal analysis of fourteen embryos revealed eleven normal females (44,XX), one normal male (44,XY), one abnormal embryo (45,XX) with an extra acrocentric chromosome and one embryo with a modal number of forty-two chromosomes in 35% of the metaphases. Since most of the embryonic wastage in aged rabbits occurred during the first 12 days post coitum, chromosome studies of embryos younger than 12 days post coitum are indicated. Most of the embryonic wastage could not be attributed to ovulation rate, fertilization rate, ovum potential, CL function, circulating levels of progesterone and oestrogen, or to chromosomal anomalies of the fetuses. It was concluded that uterine factors apparently limit reproductive performance in aged rabbits.

Down's Syndrome

Although the presence of a small extra acrocentric chromosome in Down's syndrome was described more than a decade ago, we have little reliable information on how the chromosomal imbalance produces multiple physical and chemical changes described in the syndrome. In this paper, we will critically review the many reports on the enzyme changes found in Down's syndrome, the studies on the production of DNA and RNA following phytohemagglutinin stimulation of lymphocytes, and the possibilities that Down's syndrome may represent the end result of the action of a susceptibility gene in the mother which would alter the balance between Australia antigen, hepatitis, and leukemia.

Survey of 500 cases of down’s syndrome

Dr. John Langdon Haydon Down became Medical Superintendent of the Earlswood Asylum for Idiots in Surrey in 1858, and in 1866 his classic description of the syndrome that now bears his name appeared in the London Hospital Reports entitled “Observations on an Ethnic Classification of Idiots” — he named this syndrome mongolian idiocy. No further publications on mongolism appeared until 1876 when Fraser and Mitchell published a paper entitled “Kalmuck Idiocy”, thereafter many clinical reports followed, notably those of Shuttleworth (1883, 1886 and 1899) who coined the term “unfinished children”. Since the turn of the century, papers on mongolism appear frequently in many journals, and in 1959 Lejeune, Gautier and Turpin published their paper showing that mongols have an extra acrocentric chromosome and a total diploid chromosomal number of 47. Translocation mongols were first reported a year later by Polani et al, and mosaic mongols in 1961 by Clarke, Edwards and Smallpiece.

Anal atresia, eye anomalies, and an additional small abnormal acrocentric chromosome (47,XX,mar+): Report of a case

A 2 1/2-year-old girl had anal atresia, bilateral microphthalmia, and preauricular skin tags. Her clinical pattern resembled that of 6 reported cases, all of which had an extra small acrocentric chromosome. Chromosome analysis revealed a similar extra acrocentric chromosome, which is smaller than a G group chromosome. These clinical and cytogenetic findings support the concept of a distinctive partial trisomy syndrome. The extra chromosome shows late labeling with autoradiography using tritiated thymidine. Gene marker and chromosome family studies have not revealed any unusual inheritance patterns or the origin of the marker chromosome.