Lack of association of angiotensin I-converting enzyme gene polymorphism and premature myocardial infarction in Mauritian Indians

Eighty-five young Mauritian Indians, male survivors of premature myocardial infarction (MI) and thus belonging to a high risk group, were compared with 108 stringently selected controls for a possible association between premature MI and an insertion/deletion (I/D) polymorphism in the gene encoding angiotensin I-converting enzyme (ACE). The frequency of the D allele was 0.42 in the MI group and 0.43 in the control group, and thus no association between I/D polymorphism of ACE with susceptibility to early-onset MI was found in this population group. Other gene components of the renin-angiotensin system and lipid metabolism need to be explored to understand the genetic factors involved in causing MI at an early age.     

Killer DNA plasmids of the yeast Kluyveromyces lactis

Summary We have studied the structure of the two linear DNA plasmids, kl and k2, present in killer strains of Kluyveromyces lactis. Two killer strains of different origins, CBS 2359 and IFO 1267 were examined. For both strains, identical restriction maps of kl and k2 DNA were obtained. Several restriction sites previously reported for the kl DNA of the strain IFO 1267 have been confirmed. The molecular weights of these double-stranded DNAs were 8.8 kilobase pairs for kl and 13.4 for k2, as determined by electrophoresis of restriction fragments. The plasmid DNA from a nonkiller mutant, NK2/1, was also examined. In this mutant, the kl DNA was replaced by a smaller DNA (5.9 kilobase pairs), the k2 DNA being normal. Restriction enzyme analysis showed that the new plasmid DNA was also linear. Hybridization experiments demonstrated that it was derived from the kl DNA by deletion of a 2.9 kilobase pair segment from the central part of the kl DNA. The deleted segment carries a gene involved in toxin production, but is not related to immunity since the mutant is resistant to killers. The plasmid DNA of K. lactis showed no detectable sequence homology with the double stranded RNA of the killer system of Saccharomyces cerevisiae. Neither was any homology found with nuclear and mitochondria) DNA.     

Minicircular DNA having sequence homologies with chloroplast DNA in a bleached mutant of Euglena gracilis

Summary Chloroplast DNA was isolated from total cellular DNA of a bleached mutant of Euglena gracilis (Y₃BUD) by enrichment of the light component (p = 1.686) by repeated CsCl equilibrium centrifugations. Electron microscope visualization of this DNA showed minicircular DNA molecules in addition to large circular molecules (42 pm) identical to wild type chloroplast DNA. They were heterogenous in size and their contour lengths ranged from 0.8 to 8.5 m. Fractionnation by agarose gel electrophoresis gave several discrete bands. Some of them hybridized with pure chloroplast DNA and with several cloned chloroplast DNA fragments, particularly to ribosomal fragments, while others did not show homology with chloroplast DNA being probably of extrachloroplatic origin.     

Telomere structure, function and maintenance in Arabidopsis

The stability of eukaryotic genomes is provided in part by the integrity of telomeres, the nucleoprotein caps on the ends of chromosome. Recent studies reveal that proper telomere architecture is required for long-term proliferation capacity. Here we describe molecular mechanisms that protect and maintain chromosome ends and discuss why Arabidopsis is emerging as a powerful new model for elucidating fundamental aspects of telomere biology.     

HLA-DRB1 and -DQB1 alleles in the Brazilian population of the northeastern region of the state of São Paulo

The HLA-DRB1 and -DQB1 alleles in 161 healthy unrelated individuals, including Caucasians, Blacks and Mulattos (mixed Caucasian and Black), from the Northeastern region of the state of S?o Paulo, Brazil were analysed. The 36 different DRB1 alleles detected included not only common Caucasian alleles, but also DRB1*0411, 0807 and 1402, typical of Amerindians, and DRB1*0302, 1503, and 0804, typical of African American Blacks.     

Quantitative determination of binding of anthracycline antibiotics with DNA

Research Institute of Experimental Diagnosis and Treatment of Tumors, Oncologic Scientific Center, Russian Academy of Medical Sciences, Moscow. Troitsk Branch, I.V. Kurchatov Institute of Atomic Energy, Moscow Region. (Presented by Academician of the Russian Academy of medical Sciences, N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 6, pp. 636–638, June, 1992.     

Human herpesvirus-6 DNA in the saliva of paediatric oncology patients and controls

Children with malignancy are immunosup-pressed and susceptible to serious infections with herpesviruses. The majority of children on chemotherapy for malignancy are seropositive for human herpesvirus-6 (HHV-6), and although HHV-6 has been demonstrated to be a pathogen in severely immunocompromised patients, whether this is the case for paediatric oncology patients is unknown. HHV-6 is secreted in saliva and in this study samples were examined prospectively for HHV-6 DNA in healthy children and those with malignancy. In a nested polymerase chain reaction (PCR), a 287 bp outer fragment and 163 inner fragment of HHV-6 DNA were amplified. The resulting amplimer contained a Hind III restriction site present only in “B” type HHV-6 and this was used to identify the type of HHV-6 amplified. In saliva from healthy control children, 74% (28/38) of samples were HHV-6 DNA-positive in either the supernate, pellet or both. In the patients, 58% (45/77) of all samples were HHV-6 DNA-positive. When sequential samples from twelve patients were examined the children appeared to fall into two groups: those who were frequently HHV-6 DNA-positive (60% of samples or more) and those who were rarely HHV-6 DNA-positive (33% of samples or less) (P < 0.0001). The only apparent difference between these two groups was that the less frequently HHV-6-positive group was more often febrile and unwell with neutro-paenia. Hind III digestion demonstrated all the positive samples to be “6” type HHV-6. Possible explanations for this difference in HHV-6 secretion between the patient groups are discussed. © Wiley-Liss, Inc.     

Encomium: Theodore puck,a life in biophysics applied to medicine

The dopamine hypothesis of schizophrenia proposed that dopaminergic pathways are involved in the etiology of the disease. In particular, interest among psychiatrists has focused on the D₂ receptor because of its affinity to antipsychotic drugs. Recently a new dopamine receptor gene has been cloned, and named the dopamine D₃ receptor. The D₃ receptor is a potential site for antipsychotic drug action and may be involved in the pathophysiology of schizophrenia. We have carried out a linkage study between the susceptibility gene for schizophrenia and polymorphism of the dopamine D₃ receptor gene in two Japanese pedigrees. The LOD scores were negative for, all genetic models and for all affective status at a recombination fraction θ = 0. Linkage of DRD₃ has been excluded for the model 1 (dominant model) and the model13 (recessive model). The LOD score was - 3.43 at θ = 0 for model 1 (dominant model) and broad definition of affected status. These results were consistent with previous studies. © 1994 Wiley-Liss, Inc.     

Detection of DNA from infectious laryngotracheitis virus by colourimetric analyses of polymerase chain reactions

A combination of the polymerase chain reaction and a novel ELISA-type DNA colourimetric assay (developed from studies with a retrovirus from man) was used in a preliminary study to detect DNA from avian infectious laryngotracheitis virus. The method is sensitive, specific and easy to perform. Since it can be readily adapted for the detection of DNA from other sources it could be useful for the identification of a variety of pathogens from other species of veterinary importance.