Analysis of synaptonemal complexes in two fertile heterozygous boars, both carriers of a reciprocal translocation involving an acrocentric chromosome

An electron microscopic study of synaptonemal complexes in two heterozygous fertile boars, one a carrier of a 4;14 reciprocal translocation and the second a carrier of this translocation associated with a 3;7 reciprocal translocation, is reported. The results showed heterologous pairing in almost all quadrivalents, as well as a lack of XY-quadrivalent association. This seemed to be a common feature of translocations in pigs, even if at least one acrocentric chromosome is involved, and may represent a significant meiotic mechanism that prevents spermatocyte loss, while the production of genetically unbalanced gametes leads to loss of progeny through abortion.     

Cytogenetic observations on two ovarian carcinomas with double minutes, one with a 6q- marker chromosome

A high number of structurally altered marker chromosomes was found in two cases of ovarian carcinoma. Even by the application of different staining methods it was not possible to identify all the chromosomes. No evidence for the existence of a translocation between chromosomes 6 and 14 was found, which seems to be a specific abnormality characteristic of papillary serous cystadenocarcinomas of the ovary. It is of interest that double minutes were present in both cases. This offers further evidence for the assumption that double minutes are not infrequent in carcinomas. Their orthodox mitotic behaviour leads to high karyotype variability (number of double minutes/cell), and may be of particular importance for tumour biology. The methodological and cytogenetic implications of the results are discussed.     

Techniques of chromosome manipulation in rainbow trout: a new evaluation with karyology

Summary Experiments, supported by extensive karyology, were carried out to evaluate the different techniques used for chromosome manipulation in rainbow trout. Eggs, when subjected to early heat shocks, changed from haploidy to diploidy and from diploidy to triploidy. In this respect heat shocks differ from pressure shocks which induce gradual transitions between successive ploidy levels. Sperm treatment with dimethylsulphate yields haploid embryos containing residual sperm chromatin fragments, in contrast to treatment with ultraviolet rays.     

Reproductive consequences of a reciprocal chromosomal translocation in two Duroc boars used to provide semen for artificial insemination

Cytogenetic analysis of 58 boars at an artificial insemination (AI) centre revealed the presence of a reciprocal chromosome translocation, rcp(1;11)(q−;p+), in two Duroc boars. Pedigree analysis of these two boars suggested familial transmission of the chromosome rearrangement. The reproductive consequences of this translocation were determined in a herd of sows that had received semen doses from these and other boars. All sows underwent multiple AI, with different groups established retrospectively depending on the percentage of semen doses provided by the carrier boars ([number of carrier boar doses/total number doses provided] x 100): 0%, 25%, 50%, 75%, 100%. The fertility rates (percentage of successful multiple AIs/total multiple AIs) recorded for multiple AI including semen doses from the carrier boars were not significantly different from those recorded when all semen doses were supplied by normal-karyotype boars. A reduction in litter size of 29.38% was observed, however, in litters sired by one of the carrier boars when its participation in multiple AI was 100%. The number of live-born piglets per litter gradually decreased (P < 0.05) as the percentage participation in multiple AI (25, 50, or 75%) of the carrier boar increased. In addition, both carrier boars sired some piglets with signs of cleft palate and complex malformations of the front legs; these died soon after birth. In conclusion, the boars carrying the translocation rcp(1;11)(q−;p+) showed reduced reproductive performance.     

Cytogenetic control of a hybrid zone of between two Sorex araneus chromosome races before breeding season

Two chromosome races of common shrew, Moscow and Seliger, differ in the arm combination in 11 diagnostic chromosomes (Robertsonian metacentrics/acrocentrics). Homozygotes of both pure races, simple Robertsonian heterozygotes of Seliger race, and complex heterozygotes (FI hybrids) were detected in the found earlier between hybrid zone of these races, in the spring before the breeding seasonbreeding season. The g/oheterozygote was first discovered in race Seliger, whose chromosome formula typically contains acrocentrics g and o. The m/q heterozygote was recorded for the second time. Meiosis was studied in 16 males representing five detected karyotypic categories. No abnormal in pairing of homologs in either sex trivalent common for the species (XY1Y2) or autosome trivalents (g/o and m/q) was detected at diakinesis--metaphase I. Two hybrids displayed a theoretically expected and unimpaired meiotic configuration in a form of a very long chain comprising 11 monobrachial homologs (g/gm/mq/qp/pr/rk/ki/ih/hn/no/o). The results are discussed in terms of hypotheses on fertility of complex heterozygotes and limited gene flow in hybrid zone.     

Cytogenetic and molecular evaluation of centromere-associated DNA sequences from a marsupial (Macropodidae: Macropus rufogriseus) X chromosome

The constitution of the centromeric portions of the sex chromosomes of the red-necked wallaby, Macropus rufogriseus (family Macropodidae, subfamily Macropodinae), was investigated to develop an overview of the sequence composition of centromeres in a marsupial genome that harbors large amounts of centric and pericentric heterochromatin. The large, C-band-positive centromeric region of the X chromosome was microdissected and the isolated DNA was microcloned. Further sequence and cytogenetic analyses of three representative clones show that all chromosomes in this species carry a 178-bp satellite sequence containing a CENP-B DNA binding domain (CENP-B box) shown herein to selectively bind marsupial CENP-B protein. Two other repeats isolated in this study localize specifically to the sex chromosomes yet differ in copy number and intrachromosomal distribution. Immunocytohistochemistry assays with anti-CENP-E, anti-CREST, anti-CENP-B, and anti-trimethyl-H3K9 antibodies defined a restricted point localization of the outer kinetochore at the functional centromere within an enlarged pericentric and heterochromatic region. The distribution of these repeated sequences within the karyotype of this species, coupled with the apparent high copy number of these sequences, indicates a capacity for retention of large amounts of centromere-associated DNA in the genome of M. rufogriseus.     

Cytogenetic investigations in three cell types of a Saudi family with ataxia telangiectasia

Summary Chromosomal analyses were performed on lymphocytes, fibroblasts and lymphoblastoid cell lines derived from a Saudi family with ataxia telangiectasia (AT). The three siblings of a consanguineous marriage were all affected. The lymphocytes of the AT homozygotes (probands) showed an increase of 2- to 6-fold and 4- to 8-fold respectively, in the frequency of spontaneous and X-ray-induced chromosomal aberrations compared with controls, while the parents (obligate heterozygotes) of the patients showed no notable difference. The unirradiated lymphocytes from the oldest AT sibling, an 11-year-old boy (AT1), showed specific rearrangements involving chromosomes 7 and 14 [t(7;14)(q35;q12)] and 12 and 14 [t(12;14)(q23;q12)] in two different clones. The most severely affected sibling was a 9-year-old girl (AT2) who presented with a clone showing a novel rearrangement involving chromosomes 14 and 17, namely: del(14) (q31q32) and dup(17)(q21–q24). The lymphocytes from the third sibling, a 2-year-old boy (AT3), showed a t(2;14)(p24;q12). In addition, an inv(14)(q12q32) was observed in all three AT patients, while inv(7)(p14q35) was found only in patients 2 and 3. The lymphocytes from the AT parents and controls showed normal karyotypes. The breakpoints involving chromosomes 2,12 and 17, observed in our studies, have rarely been reported in other series of AT patients. No non-random chromosomal rearrangements were observed either in the skin fibroblasts or in the lymphoblastoid cell lines derived from the AT patients, although all cell lines showed an increase in both spontaneous and radiation-induced chromosomal breaks per cell. The present study constitutes the first report on a cytogenetic analysis of a Saudi family with three AT siblings.     

Acute leukemia with chromosome translocation (4;11): 7 new patients and analysis of 71 cases

Clinical and laboratory features of seven patients with acute leukemia associated with the (4;11) chromosome translocation are presented. Leukemic blasts of these patients showed lymphoid morphology in 6 (although 1 was treated for monoblastic leukemia 3 years earlier) and monocytoid morphology in 1, were positive for TdT and HD 37 (CD 19) in 6 patients, whereas weak expression of CALLA was seen in only 1 patient and T-lineage-associated antigens in none. Leukemic blasts from four patients showed the simultaneous expression of B-lymphoid and myeloid antigens, suggesting leukemogenesis in a very early multipotent progenitor cell. In 2 patients an isochromosome of the long arm of No. 7 chromosome was found in the leukemic karyotypes in addition to t (4; 11) (q 21; q 23); in one instance present at diagnosis, in the other one occurring at relapse. In one other patient leukemia karyotype also demonstrated trisomy 8. Leukemic cells of three patients were investigated by molecular genetics and demonstrated immunoglobulin gene rearrangements for the Ig heavy chain sequences but not for the light chain constant regions and T cell receptor sequences. All patients were treated by intensive chemotherapy. Four of the 7 patients are in continuous complete remission. The longest event-free survival time (over 2 1/2 years) was seen in one patient who had also DOWN-syndrome. Including these 7 patients a clinical analysis of 71 patients with t (4; 11) acute leukemia was made, emphasizing the following characteristics at diagnosis: female sex (62%), age under 2 years (49%), leukocyte count over 100 X 10(9)/1 (61%), splenomegaly (80%), CNS-disease (11%). Survival of over 2 years was reported in less than 15% of the patients. It remains to be seen if risk-adapted treatment can alter the course of this early B-precursor acute leukemia with hitherto very bad prognosis.     

Differential induction of chromosome puffs in two cell types of Melanagromyza obtusa

The patterns of puffing activity in polytene nuclei of salivary gland (SG) and midgut (MG) tissues of Melanagromyza obtusa have been studied after heat shock (HS), 2-4-dinitrophenol (DNP) or benzamide treatment. This study has revealed that HS and DNP treatments induced the same set of puffs but in a tissue-specific pattern. Benzamide treatment was found ineffective in inducing puffing activity. Some HS genes were also found to be more or less active during normal development, indicating some function in the normal metabolism of the cells.     

Molecular confirmation of Wolf-Hirschhorn syndrome with a subtle translocation of chromosome 4.

Wolf-Hirschhorn syndrome is a clinically recognizable, multiple congenital anomaly syndrome usually associated with terminal deletion of the short arm of chromosome 4. A girl with clinical features of Wolf-Hirschhorn syndrome did not show an obvious deletion of chromosome 4, and a molecular defect was suspected. RFLPs of genomic DNA from the proband and her parents were studied using DNA probes from the distal region of chromosome 4p. Fluorescence in situ hybridization using a cosmid p847.351 containing the fragment 847 E-C was performed to investigate the possibility of a subtle translocation. Cytogenetic analyses done on the child and on both parents did not conclusively reveal abnormalities of chromosome 4. Molecular studies using two probes mapped to distal 4p showed the absence of the maternal haplotype in the child. These findings are thus consistent with a molecular deletion of 4p and confirm the diagnosis of Wolf-Hirschhorn syndrome. Cytogenetic experiments involving fluorescence in situ hybridization showed that the mother carried a subtle translocation between chromosomes 4 and 19, 46,XX,t(4,19)(p16.3; p13.3), which resulted in an unbalanced form in the child. Chorionic villus sampling for prenatal diagnosis in a subsequent pregnancy showed the fetus to be unaffected. This provides the first evidence, in chromosome 4p, of a molecular deletion due to a subtle, inherited translocation leading to the Wolf-Hirschhorn phenotype. Such subtle translocations may become an important mechanism for some recurrent genetic defects.     

远缘杂交在转移有益基因创造小麦新种质中的潜力

本文概述了小麦远缘杂交技术的发展以及这些技术的应用对以染色体易位方式转移有益基因到普通小麦中的影响。通过对小麦远缘杂交技术的总结得出,普通小麦由于本身的多倍性,对导入的外源基因具有较强的调节能力,是适宜外源有益基因导入的良好受体。而以染色体易位方式转移有益基因是创造小麦新种质的有效方法之一,许多研究也表明以染色体易位导入的外源有益基因更利于表达。近几年,随着细胞遗传学以及其它生物技术的发展,对小麦族进化途径和染色体间的亲缘关系进一步明确,从而更便于进行易位导入的技术选择,也使得染色体易位鉴定方法更趋完善。现在已有更良好的外源导入的工具和方法,使多基因控制的外源优良性状导入成为可能。在小麦远缘杂交中染色体易位所具有的上述优势,在育种实践中逐步显示出来,为开拓小麦种质资源开创了一条新的途径。     

Ring chromosome 16: a new case

A 46,XX,r(16) "de novo" karyotype is reported in a 4 7/12-year-old girl. In spite of the mild cranio-facial dysmorphism without visceral malformations in r(16) patients, the proband's phenotype is similar to the other four previous case reports. This could support the hypothesis of a specific "r(16) syndrome".