Lesion bypass by the Escherichia coli DNA polymerase V requires assembly of a RecA nucleoprotein filament.

Translesion replication is carried out in Escherichia coli by the SOS-inducible DNA polymerase V (UmuC), an error-prone polymerase, which is specialized for replicating through lesions in DNA, leading to the formation of mutations. Lesion bypass by pol V requires the SOS-regulated proteins UmuD' and RecA and the single-strand DNA-binding protein (SSB). Using an in vitro assay system for translesion replication based on a gapped plasmid carrying a site-specific synthetic abasic site, we show that the assembly of a RecA nucleoprotein filament is required for lesion bypass by pol V. This is based on the reaction requirements for stoichiometric amounts of RecA and for single-stranded gaps longer than 100 nucleotides and on direct visualization of RecA-DNA filaments by electron microscopy. SSB is likely to facilitate the assembly of the RecA nucleoprotein filament; however, it has at least one additional role in lesion bypass. ATPgammaS, which is known to strongly increase binding of RecA to DNA, caused a drastic inhibition of pol V activity. Lesion bypass does not require stoichiometric binding of UmuD' along RecA filaments. In summary, the RecA nucleoprotein filament, previously known to be required for SOS induction and homologous recombination, is also a critical intermediate in translesion replication.

Address by Michea¡l Martin to the Conference - Legislating for Tobacco Free Society

Thank you Chairman I would like to extend a warm welcome to our keynote speakers, David Byrne of the European Commission, Derek Yach from the World Health Organisation, and Paul Quinn representing Congressman Marty Meehan who sends his apologies. When we include the speakers who will address later sessions, this is, undoubtedly, one of the strongest teams that have been assembled on tobacco control in Europe. The very strength of the team underlines what I see as a shift – a very necessary shift – in the way we perceive the tobacco issue. For the last twenty years, we have lived out a paradox. It isn´t a social side issue. I make no apology for the bluntness of what I´m saying, and will come back, a little later, to the radicalism I believe we need to bring – nationally – to this issue. For starters, though, I want to lay it on the line that what we´re talking about is an epidemic as deadly as any suffered by human kind throughout the centuries. Slower than some of those epidemics in its lethal action, perhaps. But an epidemic, nonetheless. According to the World Health Organisation tobacco accounted for just over 3 million annual deaths in 1990, rising to 4.023 million annual deaths in 1998. The numbers of deaths due to tobacco will rise to 8.4 million in 2020 and reach roughly 10 million annually by 2030. This is quite simply ghastly. Tobacco kills. It kills in many different ways. It kills increasing numbers of women. It does its damage directly and indirectly. For children, much of the damage comes from smoking by adults where children live, study, play and work. The very least we should be able to offer every child is breathable air. Air that doesn´t do them damage. We´re now seeing a global public health response to the tobacco epidemic. The Tobacco Free Initiative launched by the World Health Organisation was matched by significant tobacco control initiatives throughout the world. During this conference we will hear about the experiences our speakers had in driving these initiatives. This Tobacco Free Initiative poses unique challenges to our legal frameworks at both national and international levels; in particular it raises challenges about the legal context in which tobacco products are traded and asks questions about the impact of commercial speech especially on children, and the extent of the limitations that should be imposed on it. Politicians, supported by economists and lawyers as well as the medical profession, must continue to explore and develop this context to find innovative ways to wrap public health considerations around the trade in tobacco products – very tightly. We also have the right to demand a totally new paradigm from the tobacco industry. Bluntly, the tobacco industry plays the PR game at its cynical worst. The industry sells its products without regard to the harm these products cause. At the same time, to gain social acceptance, it gives donations, endowments and patronage to high profile events and people. Not good enough. This model of behaviour is no longer acceptable in a modern society. We need one where the industry integrates social responsibility and accountability into its day-to-day activities. We have waited for this change in behaviour from the tobacco industry for many decades. Unfortunately the documents disclosed during litigation in the USA and from other sources make very depressing reading; it is clear from them that any trust society placed in the tobacco industry in the past to address the health problems associated with its products was misplaced. This industry appears to lack the necessary leadership to guide it towards just and responsible action. Instead, it chooses evasion, deception and at times illegal activity to protect its profits at any price and to avoid its responsibilities to society and its customers. It has engaged in elaborate ´spin´ to generate political tolerance, scientific uncertainty and public acceptance of its products. Legislators must act now. I see no reason why the global community should continue to wait. Effective legal controls must be laid on this errant industry. We should also keep these controls under review at regular intervals and if they are failing to achieve the desired outcomes we should be prepared to amend them. In Ireland, as Minister for Health and Children, I launched a comprehensive tobacco control policy entitled “Towards a Tobacco Free Society“. OTT?Excessive?Unrealistic? On the contrary – I believe it to be imperative and inevitable. I honestly hold that, given the range of fatal diseases caused by tobacco use we have little alternative but to pursue the clear objective of creating a tobacco free society. Aiming at a tobacco free society means ensuring public and political opinion are properly informed. It requires help to be given to smokers to break the addiction. It demands that people are protected against environmental tobacco smoke and children are protected from any inducement to experiment with this product. Over the past year we have implemented a number of measures which will support these objectives; we have established an independent Office of Tobacco Control, we have introduced free nicotine replacement therapy for low-income earners, we have extended our existing prohibitions on tobacco advertising to the print media with some minor derogations for international publications. We have raised the legal age at which a person can be sold tobacco products to eighteen years. We have invested substantially more funds in health promotion activities and we have mounted sustained information campaigns. We have engaged in sponsorship arrangements, which are new and innovative for public bodies. I have provided health boards with additional resources to let them mount a sustained inspection and enforcement service. Health boards will engage new Directors of Tobacco Control responsible for coordinating each health board´s response and for liasing with the Tobacco Control Agency I set up earlier this year. Most recently, I have published a comprehensive Bill – The Public Health (Tobacco) Bill, 2001. This Bill will, among other things, end all forms of product display and in-store advertising and will require all retailers to register with the new Tobacco Control Agency. Ten packs of cigarettes will be banned and transparent and independent testing procedures of tobacco products will be introduced. Enforcement officers will be given all the necessary powers to ensure there is full compliance with the law. On smoking in public places we will extend the existing areas covered and it is proposed that I, as Minister for Health and Children, will have the powers to introduce further prohibitions in public places such as pubs and the work place. I will also provide for the establishment of a Tobacco Free Council to advise and assist on an ongoing basis. I believe the measures already introduced and those additional ones proposed in the Bill have widespread community support. In fact, you´re going to hear a detailed presentation from the MRBI which will amply illustrate the extent of this support. The great thing is that the support comes from smokers and non-smokers alike. Bottom line, Ladies and Gentlemen, is that we are at a watershed. As a society (if you´ll allow me to play with a popular phrase) we´ve realised it´s time to ´wake up and smell the cigarettes.´ Smell them. See them for what they are. And get real about destroying their hold on our people. The MRBI survey makes it clear that the single strongest weapon we have when it comes to preventing the habit among young people is price. Simple as that. Price. Up to now, the fear of inflation has been a real impediment to increasing taxes on tobacco. It sounds a serious, logical argument. Until you take it out and look at it a little more closely. Weigh it, as it were, in two hands. I believe – and I believe this with a great passion – that we must take cigarettes out of the equation we use when awarding wage increases. I am calling on IBEC and ICTU, on employers and trade unions alike, to move away from any kind of tolerance of a trade that is killing our citizens. At one point in industrial history, cigarettes were a staple of the workingman´s life. So it was legitimate to include them in the ´basket´ of goods that goes to make up the Consumer Price Index. It isn´t legitimate to include them any more. Today, I´m saying that society collectively must take the step to remove cigarettes from the basket of normality, from the list of elements which constitute necessary consumer spending. I´m saying: “We can no longer delude ourselves. We must exclude cigarettes from the considerations we address in central wage bargaining. We must price cigarettes out of the reach of the children those cigarettes will kill.” Right now, in the monthly Central Statistics Office reports on consumer spending, the figures include cigarettes. But – right down at the bottom of the page – there´s another figure. Calculated without including cigarettes. I believe that if we continue to use the first figure as our constant measure, it will be an indictment of us as legislators, as advocates for working people, as public health professionals. If, on the other hand, we move to the use of the second figure, we will be sending out a message of startling clarity to the nation. We will be saying “We don´t count an addictive, killer drug as part of normal consumer spending.” Taking cigarettes out of the basket used to determine the Consumer Price Index will take away the inflation argument. It will not be easy, in its implications for the social partners. But it is morally inescapable. We must do it. Because it will help us stop the killer that is tobacco. If we can do it, we will give so much extra strength to health educators and the new Tobacco Control Association. This new organisation of young people who already have branches in over fifteen counties, is represented here today. The young adults who make up its membership are well placed to advise children of the dangers of tobacco addiction in a way that older generations cannot. It would strengthen their hand if cigarettes move – in price terms – out of the easy reach of our children Finally, I would like to commend so many public health advocates who have shown professional and indeed personal courage in their commitment to this critical public health issue down through the years. We need you to continue to challenge and confront this grave public health problem and to repudiate the questionable science of the tobacco industry. The Research Institute for a Tobacco Free Society represents a new and dynamic form of partnership between government and civil society. It will provide an effective platform to engage and mobilise the many different professional and academic skills necessary to guide and challenge us. I wish the conference every success.

First characterization of Candida albicans by random amplified polymorphic DNA method in Nicaragua and comparison of the diagnosis methods for vaginal candidiasis in Nicaraguan women

A total of 106 women with vaginitis in Nicaragua were studied. The positive rate for the identification of Candida species was 41% (44 positive cultures out of 106 women with vaginitis). The sensitivity of microscopic examination of wet mount with the potassium hydroxide (KOH) was 61% and 70% with Gram's stain when using the culture of vaginal fluid as gold standard for diagnosis of candidiasis. Among the 44 positives cultures, isolated species of yeast from vaginal swabs were C. albicans (59%), C. tropicalis (23%), C. glabrata (14%) and C. krusei (4%). This study reports the first characterization of 26 C. albicans stocks from Nicaragua by the random amplified polymorphic DNA method. The genetic analysis in this small C. albicans population showed the existence of linkage disequilibrium, which is consistent with the hypothesis that C. albicans undergoes a clonal propagation.

Characterization of new Schistosoma mansoni microsatellite loci in sequences obtained from public DNA databases and microsatellite enriched genomic libraries

In the last decade microsatellites have become one of the most useful genetic markers used in a large number of organisms due to their abundance and high level of polymorphism. Microsatellites have been used for individual identification, paternity tests, forensic studies and population genetics. Data on microsatellite abundance comes preferentially from microsatellite enriched libraries and DNA sequence databases. We have conducted a search in GenBank of more than 16,000 Schistosoma mansoni ESTs and 42,000 BAC sequences. In addition, we obtained 300 sequences from CA and AT microsatellite enriched genomic libraries. The sequences were searched for simple repeats using the RepeatMasker software. Of 16,022 ESTs, we detected 481 (3%) sequences that contained 622 microsatellites (434 perfect, 164 imperfect and 24 compounds). Of the 481 ESTs, 194 were grouped in 63 clusters containing 2 to 15 ESTs per cluster. Polymorphisms were observed in 16 clusters. The 287 remaining ESTs were orphan sequences. Of the 42,017 BAC end sequences, 1,598 (3.8%) contained microsatellites (2,335 perfect, 287 imperfect and 79 compounds). The 1,598 BAC end sequences 80 were grouped into 17 clusters containing 3 to 17 BAC end sequences per cluster. Microsatellites were present in 67 out of 300 sequences from microsatellite enriched libraries (55 perfect, 38 imperfect and 15 compounds). From all of the observed loci 55 were selected for having the longest perfect repeats and flanking regions that allowed the design of primers for PCR amplification. Additionally we describe two new polymorphic microsatellite loci.

Protective immunity of single and multi-antigen DNA vaccines against schistosomiasis

We evaluated the usefulness of the combination of three plasmids encoding tegumental (pECL and pSM14) and muscular (pIRV5) antigens of the Schistosoma mansoni on improving the protective immunity over the use of a single antigen as DNA vaccines. Female BALB/c mice were inoculated twice with 25 µg DNA plasmid within two weeks interval. The challenge was performed with 80 cercarias of a regional isolate of S. mansoni (SLM) one week after the last immunization. Six weeks after challenge, all mice were perfused for worm load determination. The following groups were analyzed: saline; empty vector; monovalent formulations of pECL; pSM14 and pIRV5 and also double combinations of pECL/pIRV5 and pIRV5/pSM14 and a triple combination of pECL/pIRV5/pSM14. The protection was expressed as a percentage of worm loads in each group compared with the saline group. The results obtained were 41% (p < 0.05); 52% (p < 0.05); 51% (p < 0.05); 48% (p < 0.05); 55% (p < 0.05); 45% (p < 0.05); 65% (p < 0.05) for each group respectively.

Recent advances in the diagnosis of Schistosoma infection: the detection of parasite DNA

As Schistosoma sp. control programs are chiefly based on treatment of infected population, adequate case finding has a crucial role. The available diagnostic methods are far from ideal, since the search for eggs in stools and the detection of circulating antigens lack sensitivity in low prevalence and post-treatment situations and antibody detection lacks specificity. In most endemic foci, repeated treatment of infected people leaves a number of non-diagnosed and consequently non-treated persons, enough to maintain a persistent residue of 5 to 10% prevalence. In an attempt to surpass these diagnostic limitations we have developed a polymerase chain reaction (PCR) for the detection of Schistosoma sp. in feces that, in a first population study, has shown to be more sensitive than three-repeated stool Kato-Katz examination. The PCR may constitute a valuable tool for the diagnosis of the Schistosoma sp. infection in special situations, when high sensitivity and specificity are required and infrastructure is available.

A novel reiterated family of transcribed oligo(A)-terminated, interspersed DNA elements in the genome of Trypanosoma cruzi

We report the molecular characterization of a novel reiterated family of transcribed oligo(A)-terminated, interspersed DNA elements in the genome of Trypanosoma cruzi. Steady-state level of transcripts of this sequence family appeared to be developmentally regulated, since only in the replicative forms the parasite showed expression of related sequences with a major band around 3 kb. The presence of frame shifts or premature stop codons predicts that transcripts are not translated. The sequence family also contains truncated forms of retrotransposons elements that may become potential hot spots for retroelement insertion. Sequences homologous to this family are interspersed at many chromosomes including the subtelomeric regions.

The E.coli RuvAB proteins branch migrate Holliday junctions through heterologous DNA sequences in a reaction facilitated by SSB.

During genetic recombination a heteroduplex joint is formed between two homologous DNA molecules. The heteroduplex joint plays an important role in recombination since it accommodates sequence heterogeneities (mismatches, insertions or deletions) that lead to genetic variation. Two Escherichia coli proteins, RuvA and RuvB, promote the formation of heteroduplex DNA by catalysing the branch migration of crossovers, or Holliday junctions, which link recombining chromosomes. We show that RuvA and RuvB can promote branch migration through 1800 bp of heterologous DNA, in a reaction facilitated by the presence of E.coli single-stranded DNA binding (SSB) protein. Reaction intermediates, containing unpaired heteroduplex regions bound by SSB, were directly visualized by electron microscopy. In the absence of SSB, or when SSB was replaced by a single-strand binding protein from bacteriophage T4 (gene 32 protein), only limited heterologous branch migration was observed. These results show that the RuvAB proteins, which are induced as part of the SOS response to DNA damage, allow genetic recombination and the recombinational repair of DNA to occur in the presence of extensive lengths of heterology.