RESEARCHERS HAVE turned conventional DVDs into portable and cheap diagnostic tools for developing countries, and are now adapting their prototype into a workable medical device. A team led by Aman Russom of the KTH Royal Institute of Technology in Sweden has demonstrated proof-of-concept for the tool by testing for HIV. Blood samples are loaded into micro-channels on a modified, semi-transparent DVD disc and scanned by a DVD reader, which has been adapted to detect light transmitted through the disc. The image can then be visualised on a computer screen. Previous attempts to use CDs or DVDs for biological analysis have suffered from low image resolution or issues with malfunctioning discs. The new ‘Lab-on-DVD’ system has a resolution of one micrometre, opening up the possibility of low-cost analyses of blood cells, DNA, RNA and proteins for medical testing and diagnosis. It can provide immediate results, eliminating the need for rural patients to revisit far-flung laboratories. Russom, who was born in Eritrea, believes the device could have “a transformative effect” in regions such as his native East Africa, and he hopes to make the system a reality in the next three years. “In the first year we are going to make the technology robust; in the second we want to apply it to a clinical sample and then we will look at ways to outsource the technology to other partners,” says Russom. The project is partly funded by the European Commission (EC), and the team is now looking for clinical collaborators “who can make the technology available to patients”, as well as further funding. Russom says that the EC funding has led to a high-quality biological test, but this must now be validated in the clinic and compared with established laboratory tests. DVDs and their readers are already produced on a mass scale, meaning that the device would likely cost about US$200, less than one hundredth of the cost of standard tools used in HIV testing such as flow cytometers. DVDs themselves might be a dying product, but their manufacturing technology is well established and here to stay, according to Russom. “We’re trying to find a new use for a dying technology … the optics are superb; they have been fine-tuned over the past 30 years,” he says. Jason Warriner, clinical director of the Terrence Higgins Trust, HIV and sexual health charity based in the United Kingdom, agrees: “If you think a model or a system works and there’s low maintenance to it, then you can use it.” He adds that Lab-on-DVD could be advantageous in resource poor settings but warns that the research is in its infancy and needs “a lot of investment and development”, including assessing its accuracy and making sure the device is appropriate for use in the developing world. The proof-of-concept study was published online in Lab on a Chip earlier this year. (SciDev)
Overfishing threatens key grouper species
A QUARTER of grouper fish species face extinction or are near threatened because of overfishing and poor management of coral reef fisheries, and a further 30 per cent are so understudied there is not enough data to assess how threatened they are, according to a study. Urgent conservation efforts are needed to tackle overexploitation and improve the management of these commercially-important fisheries, according to the study to be published in the June issue of Fish and Fisheries. Most of the threatened and data-deficient species live in the developing world, where they provide crucial food and incomes, the study finds. Groupers are found predominantly in the tropics and subtropics and they are estimated to be a multi-billion dollar a year industry, says the study. Yvonne Sadovy de Mitcheson, lead author of the study and a professor at the University of Hong Kong, China, says: “Groupers are caught mainly by local fishermen who sell them to local markets or traders who may export or sell them to big businesses”. But they are also caught by big industrial fishing boats, which remove them at unsustainable scales, she says. Global catches of groupers rose by nearly 25 per cent between 1999 and 2009 to 275,000 tonnes a year, according to Food and Agriculture Organization figures in the study. The studysets out major threats to the world’s 163 grouper species based on existing assessments using International Union for Conservation of Nature criteria. It shows that 20 species, or 12 per cent of all grouper species, are at risk of extinction if overfishing trends continue, with a further 13 per cent near threatened. The majority of these threatened species live in the Caribbean Sea, off Brazil and in the Coral Triangle, which consists of marine waters of Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands and Timor-Leste. For 50 grouper species, there was insufficent data to even evaluate how threatened they are. The study indicates that, while some management of grouper fisheries exists, challenges remain to ensure their protection and introduce long-term and species-specific monitoring. “Groupers have slow life cycles, which means that they are among the more vulnerable types of species and easier to overfish than many other species,” Mitcheson says. “Fishermen need to understand that the seas are not endless,” she says. “Source countries need to manage their reef resources, which are naturally limited and not very productive, with the food security of their people as a top priority.” If this is impossible, nations could consider banning commercial exports of reef fish, she says. John Randall, a senior ichthyologist at the Bernice Pauahi Bishop Museum, Hawaii, says that large-scale fishing by foreign nations causes major problems. “Most alarming are the large fishing vessels from China — especially Hong Kong — that visit developing countries such as Indonesia to fish, often illegally, for groupers and other large fishes,” he says. A study published online in Fish and Fisheries in March estimated that China alone underrepresents its overseas fish catch by an order of magnitude, especially in the waters off West Africa. “The problem of underreporting catches or of illegal catches is very serious,” Mitcheson says, adding that it “undermines our understanding of fishery conditions and affects our ability to manage fisheries”. (SciDev)
============================================