Telomerase activity in cell lines and lymphoma originating from Bloom syndrome.

Bloom syndrome (BS) is characterized by premature aging and high predisposition to various types of cancer. BLM is the causative gene for BS. BLM functions as a DNA helicase in the direction of 3' to 5' and small subsets of telomeres colocalize with BLM protein. We investigated telomerase activity and telomere repeat length in the cells from BS patients. In Epstein-Barr-virus (EBV) transformed lymphoblastoid cell lines and lymphoma cells from BS patients, telomerase activity was detected as in the control and compared. The metastatic tumor from BS patient, which had a 9-bp deletion of p53 DNA showed the strongest telomerase activity. Telomere repeat length in BS cells showed that there is no large difference compared with normal cells. Collectively, the results show that the BLM gene is not a major structural and regulatory factor in maintaining telomere repeat length and telomerase activity.

[Epidemiological surveillance of trachoma in a school in a city of southeast Brazil]. / Vigilância epidemiológica do tracoma em instituição de ensino na cidade de São Paulo, SP.

INTRODUCTION: Epidemiological surveillance activities undertaken after the detection of an active trachoma case in the APAE-SP are described. MATERIAL AND METHOD: A total of 1,009 pupils, employees and household contacts had an eye examination. Treatment control was carried out at the institution 4 times at 45 day-intervals. RESULTS: The overall prevalence was of 5.9%, 5.1% being of follicular trachoma (TF), 0.3% of intense trachoma (TF/TI) and 0.5% of cicatricial trachoma (TS). At the first control exercise 45.5% of the trachoma cases had no signs of the disease and 40.0% underwent treatment. At the last control exercise 20% were found to have been cured with no vestigial scars. Non-attendance was of 38.2%. The distribution of secondary cases showed great dispersion, suggesting dissemination throughout Greater S. Paulo. DISCUSSION AND CONCLUSIONS: The trachoma control activities do not show satisfactory results, perhaps due to the prolonged duration of the treatment and follow-up. The development of strategies of clinical intervention should be implemented for better control of the disease.

Gene 61.3 of bacteriophage T4 is the spackle gene.

The bacteriophage T4 e gene encodes lysozyme (e-lysozyme), which releases progeny phage after normal infection of Escherichia coli cells. A mutation in the spackle gene suppresses the defect in e-lysozyme (Emrich, 1968). The spackle gene was mapped between genes 41 and 61, but its precise location has not previously been determined. In the current study, we constructed an amber mutant of gene 61.3, amST14, by site-directed mutagenesis. The gene 61.3 mutant shares phenotypes with spackle mutants: The amST14 mutant forms large plaques with sharp edges and exhibits truncated lysis inhibition, and furthermore, the mutation can suppress the defect in e-lysozyme activity. In addition, cloned gene 61.3 can rescue (by homologous recombination) as well as complement the S12 mutation in the spackle gene. These results strongly suggest that gene 61.3 is the spackle gene. Indeed, the S12 mutant has one base deletion of five in a consecutive A tract in the gene 61.3 coding region, substituting an unrelated 6-amino acid sequence for the 9 C-terminal amino acids in the gene 61.3 protein. The gene 61.3 protein is predicted to localize in the periplasmic space after cleavage of a signal sequence.

Expression of the BLM gene in human haematopoietic cells.

Bloom's syndrome (BS) is a rare autosomal recessive disorder characterized by stunted growth, sun-sensitive erythema and immunodeficiency. Chromosomal abnormalities are often observed. Patients with BS are highly predisposed to cancers. The causative gene for BS has been identified as BLM. The former encodes a protein, which is a homologue of the RecQ DNA helicase family, a family which includes helicases such as Esherichia coli RecQ, yeast Sgs1, and human WRN. WRN is encoded by the gene that when mutated causes Werner's syndrome. The function of BLM in DNA replication and repair has not yet been determined, however. To understand the function of BLM in haematopoietic cells and the cause of immunodeficiency in BS, expression of the BLM gene in various human tissues and haematopoietic cell lines was analysed and the involvement of BLM in immunoglobulin rearrangement examined. In contrast to WRN, BLM was expressed strongly in the testis and thymus. B, T, myelomonocytic and megakaryocytic cell lines also expressed BLM. All of the examined sequences at the junction of the variable (V), diversity (D) and joining (J) regions of the immunoglobulin heavy-chain genes were in-frame, and N-region insertions were also present. The frequency of abnormal rearrangements of the T cell receptor was slightly elevated in the peripheral T cells of patients with BS compared with healthy individuals, whereas a higher frequency of abnormal rearrangements was observed in the cells of patients with ataxia-telangiectasia (A-T). In DND39 cell lines, the induction of sterile transcription, which is required for class switching of immunoglobulin heavy-chain constant genes, was correlated with the induction of the BLM gene. Taking into consideration all these results, BLM may not be directly involved in VDJ recombination, but is apparently involved in the maintenance of the stability of DNA.