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Lethal burn-induced bacterial translocation: role of genetic resistance.

Since genetic factors may influence outcome after trauma or during infection, the current experiments were performed to examine the resistance of three genetically different mouse strains to burn-induced bacterial translocation. Outbred ICR, inbred Balb/c, and inbred C57/B1 mice, with a normal or disrupted (monoassociated with Escherichia coli C25) GI tract microflora, were subjected to sham or actual 25% body burns. In Balb/c, but not ICR mice, replacing the normal intestinal microflora with E. coli C25 converted the thermal injury from a nonlethal (0% mortality) to a lethal (68% mortality) injury. The increased mortality of the burned Balb/c mice monoassociated with E. coli C25 was associated with a higher incidence (p less than 0.05) and magnitude (p less than 0.05) of E. coli C25 translocation from the GI tract. The C57/B1 mice were intermediate between the Balb/c and ICR strains, in that C57/B1 mice monoassociated with E. coli C25 had a higher mortality and greater E. coli C25 translocation than mice with a normal microflora after thermal injury. Thus the composition of the intestinal microflora as well as the genetic background of the host influence the susceptibility of the host to burn-induced bacterial translocation and survival.

Animals↗

[Genetic counseling in reciprocal translocations].

Segregation modes of human reciprocal translocations are briefly described. Risk figures and mode of imbalance at term differ greatly from one translocation to another. The causes of these variations are analysed and a genetic counselling proposed for each case.

Chromosome Aberrations↗

Partial trisomy 12q: a clinically recognisable syndrome. Genetic risks associated with translocations of chromosome 12q.

A newborn child with an unusual facial appearance and multiple abnormalities was found to be trisomic for a large part of 12q as a result of adjacent 1 segregation of a familial translocation, t(9;12) (p24;q21.2). A combination of cytogenetic analysis, clinical features, and enzyme marker studies allows an accurate assessment of the breakpoints. Although trisomic for a considerably larger area of 12q than other reported cases, there are many similar features suggesting that trisomy 12q is a clinically recognisable syndrome. The frequency and mode of segregation of 12q translocations and their implications for genetic counselling are discussed.

Chromosome Aberrations↗

[Advances in preimplantation genetic diagnosis for chromosomal translocation carrier].

Chromosomal translocation is a kind of common chromosomal abnormality. The carriers with chromosomal translocation could have more chance of normal pregnancy with the help of fluorescence in situ hybridization(FISH). This is a review aimed at analyzing the meiosis types of the translocation chromosome. The strategy of preimplantation genetic diagnosis for the carriers with chromosomal translocation is also discussed.

Humans↗

Formation, translocation and resolution of Holliday junctions during homologous genetic recombination.

Over the past three or four years, great strides have been made in our understanding of the proteins involved in recombination and the mechanisms by which recombinant molecules are formed. This review summarizes our current understanding of the process by focusing on recent studies of proteins involved in the later steps of recombination in bacteria. In particular, biochemical investigation of the in vitro properties of the E. coli RuvA, RuvB and RuvC proteins have provided our first insight into the novel insight into the novel molecular mechanisms by which Holliday junctions are moved along DNA and then resolved by endonucleolytic cleavage.

Bacteria↗

Dysregulation of lymphocyte proliferation by chromosomal translocations and sequential genetic changes.

Enzymatically mediated rearrangement of Ig and T-cell receptor genes is essential for generating the huge molecular repertoire of the mammalian immune system, but it also carries a danger for the organism in the form of high risk zones for illegitimate juxtaposition of DNA from other areas of the genome. Translocation-dependent activation of oncogenes, transcription factors or developmental genes can trigger the development of neoplasia in a lineage-specific fashion. These events are not sufficient for tumorigenesis, however, since some of the most prominent tumor-associated translocations, such as Ig/myc and Ig/bcl-2, have been detected in normal individuals who did not develop tumors. Tumor development must, therefore, require subsequent genetic changes. Among them, the increased expression of genes that protect against apoptosis or, alternatively, mutations that cripple apoptosis-activating genes play a prominent role. Some of the translocations associated with T-cell leukemia, myeloid leukemia, and a variety of sarcomas act by generating fusion proteins. The participating genes encode transcription factors and/or developmental regulators. Fusion protein-expressing cells may serve as targets for specific interference with abnormal signaling pathways or for targeted immune attack. Using PCR to detect cells carrying such translocations is useful for tumor diagnosis, prognosis, and choice of therapy.

Abelson murine leukemia virus↗

Preimplantation genetic analysis of translocations: case-specific probes for interphase cell analysis.

Carriers of balanced translocations show an increased risk of infertility and spontaneous abortions, because of errors in gametogenesis, and constitute a significant fraction of patients seeking assisted reproduction. The objective of this study was to design approaches for preimplantation diagnosis of chromosome translocations and to apply such techniques to the selection of chromosomally normal or balanced embryos prior to their transfer to the mother's womb. Three slightly different approaches were assessed by means of chromosome-specific, non-isotopically labeled DNA probes and an assay based on fluorescence in situ hybridization- to score and characterize chromosomes in single blastomeres biopsied from embryos on their third day of development. The three approaches were used for preimplantation genetic diagnosis involving four couples who had enrolled in our IVF program and in which one of the partners was a carrier of one of the following translocations: 46,XX,t(12;20)(p 13.1 ;q 13.3), 46,XY,t(3;4) (p24;p15), 45,XY,der(14;15)(10q;10q), and 46,XY,t(6;11) (p22.1;p15.3). A total of 33 embryos were analyzed, of which 25 (75.8%) were found to be either unbalanced or otherwise chromosomally abnormal. Only a single embryo could be transferred to patients A and D, whereas three embryos were transferred to patient B in a total of two IVF cycles. Transfer of two embryos to patient C resulted in an ongoing pregnancy. Re-analysis of non-transferred embryos with additional probes confirmed the initial results in 95% (20/21) of the cases. In conclusion, case-specific translocation tests can be applied to any translocation carrier for the selection of normal or chromosomally balanced embryos prior to embryo transfer. This is expected significantly to increase the success rates in IVF cycles of translocation carriers, while preventing the spontaneous abortion or birth of abnormal offspring.

Adult↗

Genetic analysis of 8;21 chromosomal translocation without AML1 gene involvement in MDS-AML.

We have investigated a case of acute myelocytic leukaemia derived from myelodysplastic syndrome (MDS-AML) with an 8;21 translocation. In this case the AML1/MTG8 (ETO) fusion transcript was not detected by reverse transcriptase-polymerase chain reaction (RT-PCR), and the rearrangement of the AML1 gene locus was not detected by Southern blot nor pulse field gel electrophoresis (PFGE) analyses using specific probes for the AML1 gene. Fluorescence in-situ hybridization (FISH) study using cosmid probes for 21q22 revealed that the breakpoint of 21q22 was telomeric to the AML1 gene locus and centromeric from D21S259, 351, 3421 loci. This is the first report concerning the t(8;21)(q22;q22) carrying AMLs (de novo AML, MDS-AML and therapy-related AML) to show that the breakpoint at 21q22 is located outside the AML1 gene locus. It is also noteworthy that the cell-surface antigen expression pattern of the bone marrow (BM) blasts was changed from CD7+ CD2+ CD13+ CD33+ CD19- CD11b+ CD14+ CD36+ to CD7- CD2- CD13+ CD19+ CD11b- CD14- CD33+ CD34+ CD36- CD56+ during leukaemic progression, and the pattern in leukaemic phase was similar to the characteristic phenotype of de novo AML cases with t(8;21), when the AML1/MTG8 fusion transcripts are always detected by RT-PCR.

Blotting, Southern↗

Management of wild ungulate populations in Italy: captive-breeding, hybridisation and genetic consequences of translocations.

Captive-reproduced stocks of some species of ungulates (Artiodactyla), and particularly the red deer (Cervus elaphus), fallow deer (Dama dama), roe deer (Capreolus capreolus) and the wildboar (Sus scrofa) are more or less extensively translocated in Italy, mainly for local reintroductions or restocking of exploited wild populations. However, captive breeding often involves the reproduction of non-indigenous individuals or the production of artificial hybrids. Consequently, translocations of captive-reproduced ungulates are of concern for the conservation of indigenous populations and gene pools. The impact of translocations should be evaluated within the background of the growing knowledge on population genetic and phylogeographic structure of ungulates. Molecular genetic markers are being used to map geographic genetic diversity, and reconstruct the phylogeographic history of natural populations (i.e., in the roe deer). Molecular makers are also used to detect the consequences of domestication and identify hybrids between wild and domesticated populations (i.e., in the wildboar), or to detect inter-specific hybridisation (i.e., between the red deer and wapiti). Hybridisation of wild and domestic pigs, and diffusion of hybrids in nature is widespread in Italy. Admixture of indigenous and non-indigenous roe deer stocks is also widespread. Therefore, conservation and management of indigenous ungulates calls for careful evaluation of captive-reproduced stocks.

Animals↗

Preimplantation genetic diagnosis for an insertional translocation carrier.

BACKGROUND: While preimplantation genetic diagnosis (PGD) is well established for carriers of reciprocal terminal translocations, reports on PGD for insertional translocation carriers are lacking. Here, we report on the PGD of an insertional translocation carrier with karyotype 46,XX,ins(14;2)(q21;q31q35). Due to the possibility of crossovers within the inserted region, rather than a single probe, four probes are required for proper embryo selection. METHODS: Probes were generated for PGD using fluorescence in situ hybridization and two PGD cycles. RESULTS: Analysis of 10 embryos revealed four embryos to be normal diploid. Two embryos were consistent with 3:1 segregation of the theoretical quadrivalent and one was consistent with 2:2 or 1:1 segregation. Furthermore, one embryo was mosaic abnormal and one remained without diagnosis. CONCLUSIONS: With increased acceptance of PGD, it is likely that more carriers of complex translocations will enter PGD programmes. The present results suggest that a careful genetic work-up of complex translocations is essential for proper embryo selection. While theoretical modelling may predict that quadrivalents will form during the meiosis of insertional translocations, experimental proof for the occurrence of quadrivalents is still lacking and more research on the meiotic process of both female and male insertional translocation carriers is warranted.

Blastocyst↗

Predictability of preimplantation genetic diagnosis of aneuploidy and translocations on prospective attempts.

The aim of this study was to determine if the outcomes of aneuploidy and translocation testing by preimplantation genetic diagnosis (PGD) at the 8-cell stage have a predictive value for new genetic diagnosis cycles. In total, 83 cycles (39 patients) undergoing PGD of translocations and 378 cycles (176 patients) of aneuploidy were included. Predictability, defined as having similar rate (+/-20%) of euploid embryos in the first and successive cycles, was found in 66% of patients undergoing aneuploidy testing. Predictability was found significantly more often in patients undergoing PGD of translocations (90%, P = 0.006). In addition, patients with 0, <30 or > or =30% euploid embryos in the first cycle were compared and groups 0 and <30% had significantly fewer euploid embryos in the second cycle (22-26%) than those of the group with > or =30% (37%) (P < 0.05). Patients who did not become pregnant after the first attempt were stimulated more aggressively than those becoming pregnant, producing significantly more embryos in the second than in the first cycle (P < 0.001). Therefore, correlation between euploidy rate and pregnancy rate could not be assessed objectively between cycles. In conclusion, the PGD results of a first cycle can predict the results of the second cycle, but this is likely to be of more value when the condition investigated is translocation rather than aneuploidy. The chance of pregnancy is usually related to the number of euploid embryos.

Abortion, Habitual↗

Spontaneous abortions are reduced after preconception diagnosis of translocations.

PURPOSE: Preimplantation genetic diagnosis of translocations has seldom been attempted. Recently, a genetic test based on analyzing polar bodies at the methaphase stage, following fluorescent in situ hybridization with commercially available whole-chromosome painting DNA probes has been presented. Here we report the use of this method in seven couples in whom the female was a carrier of one of these balanced translocations: 45,XX,der (13q;14q)(q10;q10) (two cases), 46,XX,t(4;14)(p15.3;q24), 45,XX,der(14q;21q) (q10;q10), 46,XX,t(7;20)(q22;q11.2), 46,XX,t(9,11)(p24;q12), 46,XX,t(14;18)(q22;q11), and 46,XX,t(3;8)(q11;q11). METHODS: The original method was improved in two ways. First, centromeric probes for one or both chromosomes involved in the translocation were added to avoid misdiagnosis caused by possible confusion of first polar body monovalent chromosomes (with two chromatids each) with single chromatids. Second, for cases with terminal translocations where commercially available probes do not cover telomere sequences, a telomere probe labeling the translocated fragment was added. RESULTS: A total of 26 abnormal, 18 balanced, and 22 normal eggs was detected. Nine normal and seven balanced embryos were transferred, resulting in eight (50%) implanting, of which one spontaneously aborted. To date, the remainder have produced karyotypically normal or balanced babies and ongoing pregnancies. The rate of spontaneous abortions after preimplantation genetic diagnosis (12.5%) was significantly reduced (P < 0.001) compared to natural cycles in the same patients (95%). CONCLUSIONS: With the above improvements, the test can characterize any translocation of maternal origin and produce a high pregnancy rate and an apparently low frequency of spontaneous abortion.

Abortion, Spontaneous↗

Genetic selection for reciprocal translocation at chosen chromosomal sites in Saccharomyces cerevisiae.

We have constructed viable Saccharomyces cerevisiae strains containing a reciprocal translocation between the URA2 site of chromosome X and the HIS3 site of chromosome XV. Our methodology is an extension of the method originally developed to introduce an altered cloned sequence at the chromosomal location from which the parent sequence was derived (S. Scherer and R.W. Davis, Proc. Natl. Acad. Sci. U.S.A. 76:4951-4955, 1979). It comprises three essential steps. First, a nonreverting ura2- strain was constructed by deleting a 3.7-kilobase fragment from the coding sequence of the wild-type URA2 gene. Second, part of the coding sequence of the wild-type URA2 gene (without promotor) was inserted at the HIS3 locus of the ura2- strain. Third, after several generations of growth on uracil-supplemented medium, ura2+ colonies were selected which resulted from mitotic recombination between the nonoverlapping deletions of URA2 located on chromosomes X and XV.

Chromosomes↗