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β-thalassemia mutations in the Portuguese population 总被引:2,自引:0,他引:2
M. P. Coutinho Gomes M. G. Gomes da Costa L. B. Braga N. T. Cordeiro-Ferreira A. Loi M. Pirastu A. Cao 《Human genetics》1988,78(1):13-15
Summary In this study we have carried out haplotype analysis on the -globin gene cluster and characterized the -thalassemia mutation by oligonucleotide hybridization in 14 patients with thalassemia major and 5 with sickle cell/-thalassemia originating from southern Portugal. We found that three mutations, namely the °-39, ° IVS-1 nt 1 and + IVS-1 nt 110 are prevalent accounting for 53%, 32% and 10% of the -thalassemia chromosomes respectively. In general each mutation was associated with a specific chromosomal haplotype; the ° mutation, however, was linked to three different haplotypes. These results indicate that three oligo-probes complementary to the most common mutations allow prenatal diagnosis by oligonucleotide analysis in 96% of the couples at risk of having offspring with thalassemia major in southern Portugal. 相似文献
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Assessment of arterial-venous differences across transplanted methylcholanthrene-induced sarcomas in rats revealed significant decreases in plasma concentrations of glutamine, serine and glucose. Treatment with the glutamine antimetabolite, acivicin, significantly reduced tumor weights by 65% at the conclusion of the experiment 34 days after tumor induction. These results suggest that glutamine is an essential metabolic substrate for tumor growth and that blockade of glutamine utilization can inhibit the growth of these transplantable sarcomas. 相似文献
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Variable expression of latent membrane protein in nasopharyngeal carcinoma can be related to methylation status of the Epstein-Barr virus BNLF-1 5''-flanking region. 总被引:7,自引:5,他引:2 下载免费PDF全文
L F Hu J Minarovits S L Cao B Contreras-Salazar L Rymo K Falk G Klein I Ernberg 《Journal of virology》1991,65(3):1558-1567
Seven virus-coded proteins, the nuclear proteins EBNA-1 to EBNA-6 and the latent membrane protein (LMP), are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines. In nasopharyngeal carcinoma (NPC), only EBNA-1 is regularly expressed; LMP is detected in about 65% of the tumors. In Burkitt's lymphoma tumors only EBNA-1 is expressed. We have recently shown that the methylation patterns of the EBV genome varied between these cell types. In virally transformed lymphoblastoid cell lines of normal origin, the EBV DNA is completely unmethylated. In contrast, in the Burkitt's lymphoma-derived cell line Rael and in a nude mouse-passaged NPC tumor, C15, there was an extensive methylation of CpG pairs. The methylation extended into the coding regions of the two expressed genes, EBNA-1 (in both tumor types) and LMP (in C15). Two presumptive control regions were exempted from this overall methylation: the oriP that contains both an origin of DNA replication and an EBNA-1-dependent enhancer and the 5'-flanking region of the BNLF-1 open reading frame that codes for LMP. The latter was only exempted in the LMP expressing NPC. We have now investigated the relation between expression of LMP and methylation of DNA in the 5'-flanking 1 kb region of BNLF-1, coding for LMP. LMP was methylated in 3 of 12 NPC biopsies that did not express LMP but was partially or totally unmethylated in the remaining 9 that expressed the protein. The three BNLF-1 exons were highly methylated in all the tumors. The oriP region was unmethylated in all the tumors, as in the previously studied Rael cell line and nude mouse-passaged NPC. Also, the BamHI W enhancer region involved in the expression of EBNA nuclear proteins was methylated. None of the biopsies expressed EBNA-2. Our data show that the EBV genomes are highly methylated in NPC tumors. The strong reverse correlation between the methylation of the putative control region of the LMP gene and the expression of LMP suggests that methylation has a role in the regulation of this gene. 相似文献
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Temporal comparison of recombination and synaptonemal complex formation during meiosis in S. cerevisiae 总被引:53,自引:0,他引:53
In synchronous cultures of S. cerevisiae undergoing meiosis, an early event in the meiotic recombination pathway, site-specific double strand breaks (DSBs), occurs early in prophase, in some instances well before tripartite synaptonemal complex (SC) begins to form. This observation, together with previous results, supports the view that events involving DSBs are required for SC formation. We discuss the possibility that the mitotic pathway for recombinational repair of DSBs served as the primordial mechanism for connecting homologous chromosomes during the evolution of meiosis. DSBs disappear during the period when tripartite SC structure is forming and elongating (zygotene); presumably, they are converted to another type of recombination intermediate. Neither DSBs nor mature recombinant molecules are present when SCs are full length (pachytene). Mature reciprocally recombinant molecules arise at the end of or just after pachytene. We suggest that the SC might coordinate recombinant maturation with other events of meiosis. 相似文献
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