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BIOLOGY
Steps to safeguard health of sex workers
For further information contact: Windell L. Rivera Institute of Biology University of the Philippines Diliman Email: wlrivera@science.upd.edu.ph
Compensating for lost genes Research from the RIKEN Plant Science Center has shed light on the relationship between genes and their phenotypic effects. A study on the species Arabidopsis thaliana has revealed the roles of two processes that compensate for gene loss. The standard approach of knocking out individual genes to assess their effect on an organism’s biological characteristics or “phenotype” runs into the problem of genetic robustness: organisms compensate for gene loss by reproducing the gene’s function via other means. Narrowing this effect to genes responsible for producing metabolites – the products of biochemical reactions – two compensation mechanisms enable this to happen. Either
TOMAS CASTELAZO
A recent study at the University of the Philippines Diliman revealed different strains of the parasite Trichomonas vaginalis, as well as identifying high-risk individuals to help to target intervention efforts. Trichomonas vaginalis is a non-viral parasite that causes trichomoniasis, a sexually transmitted infection (STI) common throughout the world. The Philippines study took 57 isolates of T. vaginalis from across the country, and DNA sequencing identified six different sequence types. Two were represented by high numbers of isolates, showing the variations were not just random mutations but are different strains of the T. vaginalis parasite. The distinctions may allow correlations to be made between different strains and corresponding clinical symptoms. The prevalence of T. vaginalis in female sex workers in Angeles City, Pampanga, was determined using vaginal swabs. Of the 377 participants in the study, 9.55 per cent were infected with T. vaginalis, the most highly affected being among 18-22 year olds. The polymerase chain reaction (PCR) method used was very sensitive, amplifying the T. vaginalis DNA from just one cell. Angeles City is a priority area for STI control and human immunodeficiency virus (HIV) prevention. Understanding the virulence of parasitic organisms is essential for planning preventative measures. The results of the study could help to set specific guidelines for T. vaginalis screening and enable intervention efforts to be targeted at high-risk groups. T. vaginalis has been shown to be a co-factor in HIV transmission, so reducing the spread of this STI-causing parasite will help to reduce the risk of HIV transmission and infection.
the metabolites can be produced by duplicate genes on the genome, or the reactions producing the metabolites can occur through alternative chemical pathways in “metabolic networks”. The species Arabidopsis thaliana was chosen to investigate these two compensation mechanisms, since, according to lead researcher Kousuke Hanada, “Arabidopsis suited our purposes beautifully because many gene knockout mutants have been generated and many of its metabolic networks are known.” To study the robustness of Arabidopsis metabolic networks the researchers knocked out individually some 2,000 genes and analysed the effects on 35 metabolites; 17 out of 35 were primary metabolites found in all organisms, while the remaining 18 were secondary metabolites produced specifically by Arabidopsis and its relatives. The results revealed two important findings. First, only duplicate genes with very high similarity to a missing gene play a significant role in compensating for effects on metabolite production. Second, any effects on the production of primary metabolites tended to be compensated for by alternative pathways. Together, the results uncover a complementary relationship between compensation mechanisms in Arabidopsis, indicating that duplicate genes play an important role only when the number of alternative pathways is low. Primary metabolites are more likely than secondary metabolites to be essential for plant survival, and Dr Hanada suggests that the existence of multiple alternative pathways for producing primary metabolites makes these particular Arabidopsis networks highly robust to the loss of individual genes. “Our findings shed valuable new light on the gene–phenotype relationship, laying the groundwork for new theoretical models in systems biology,” Dr Hanada observed. For further information contact: Dr Kousuke Hanada Gene Discovery Research Group RIKEN Plant Science Center, Japan Email: kohanada@psc.riken.jp
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