SCIENCE & TECHNOLOGY CM YK CH-CH 18 THE HINDU THURSDAY, NOVEMBER 15, 2012 CHENNAI Poor adult health due to childhood abuse The psychological scars of childhood abuse can have long-term negative physical effects, as well as emotional ones, well into adulthood. Easing cancer symptoms by massage A new study shows that a type of ancient foot massage can help cancer patients manage their symptoms and perform daily tasks. N ecessity is the mother of natural selection. When conditions become threaten- ing, maverick or mutant members of a group which can cope with the threat sur- vive and multiply. The latest example is the discovery of a special type of bacteria in the ocean, which join together to form a long conducting nano- wire cable to transport elec- trons and capture the oxygen at the surface for metabolic use. This wire is not made of metal, alloy or other usual material, but of living biolog- ical cells. The report by Dr. Christian Pfeiffer and others in the 8 November 2012 issue of Nature is a live example of the Panchatantra tale which teaches the value of cooper- ation between individuals to win over a problem. All organisms gain energy for living through metabo- lism. The vital step in the process is the burning or ox- idation of the food molecules. Chemists define oxidation as the loss of electrons and re- duction as the gain of elec- trons. We burn our food by the breathing of oxygen in the air. When we oxidize our food and gain energy, the oxygen molecule is reduced by ac- cepting or gaining electrons to make water, while the food molecule is oxidized by losing electrons; this is not much different from burning petrol for energy. What if no oxygen? What about organisms that live in places where there is no oxygen? They too metabo- lize their food through oxida- tion. But, rather than oxygen, they utilize whatever elec- tron-acceptor molecules are available in the environment. One such group lives in ma- rine sediments, below the surface, and it use the sul- phates in the sediment as the electron-acceptors for ‘burn- ing’ and gaining energy, an example of making do with available resources. In the process, however, the sul- phate gains electrons and is reduced all the way to hydro- gen sulphide (H2S), a poison- ous material. How then is this sulphide removed? The problem Look at the problem. If H2S can be oxidized to sulphur, the situation turns safer. But in the process electrons are liberated and should be ac- cepted by a partner. If only oxygen at the surface can be reached and the electrons transferred to it, we will have H2S becoming S and the O2 reduced to H 2O. How does one transfer the electrons centimetres away? It is no longer a process within the cell where reactions happen within nanometres, and the oxidant and reductant mole- cules are in contact. What is needed is an efficient method — an electrical cable or wire for transporting the electrons from the sulphide to the ox- ygen above. It is here that biology springs an unexpected sur- prise. In the sedimental layer beneath the marine surface lives a class of anaerobic bac- teria called Desulfobulba- ceae, which Pfeffer and colleagues find to densely populate the sediments. And these live not as individuals but in groups strung together as long, multicellular fil- aments or rods, some as long as 1.5 centimetres. And these filaments reach out from the sulphide-rich sedimental lay- er to the aerobic top layer a few centimetres above, which has dissolved oxygen (from the air). These filaments thus connect the anoxic layers to the oxic layer. And what do they do? They capture the electrons generated when the H2S is oxidized to S at the bottom, and transport them all the way to the oxygen at the top, which accepts them and generates water or H2O. In other words, the Desulfo- bulbaceae bacteria line up to make a live wire. The researchers conducted a series of experiments to show how the filaments form and work. They layered the sedimental layer below in the lab and covered is with the overlying oxic sea water and studied the process. As the sulphide oxidation happened in the deeper anoxic layers, distinct change in the pH was noticed, confirming the proc- ess. And when they gently dis- turbed the layer, they found the 12-15 run long fibrous fil- aments entangled. Genetic analysis of the filaments showed their identity as Des- ulfobulbaceae. It appears that at least 40 million cells come together to assemble fil- aments of lengths as much as 1.5 cm, showing that the bac- teria could span the length of the entire anoxic layer. Liquid-filled layer Electron microscopy showed that the cells were connected lengthwise, and each cell had a liquid-filled layer in the periplasmic space between the outer and inner cytoplasmic membranes. These liquid compartments formed ridges connecting the each cell to its neighbour, suggesting electron transport occurring through this fluid tubular structure covered with a continuous outer membrane along the filament acting as the insulator — the ancient precursor, if you will, of the electric cable of today. Hair-like appendages, called pili, of some bacteria are known to be electron trans- porters, but the whole cell acting so, and joining with others to make a conducting wire is novel, and reported for the first time. Plenty of room The physicist Richard Feynman famously remarked that there is plenty of room at the bottom. Bacterial fil- aments acting as electric na- nowires is but one example. Some cyanobacteria called Anabena, which are able to ‘fix’ nitrogen, also form such continuous periplasmic fil- aments. And when a fluores- cent protein was engineered into some its cells, the fluo- rescence was found to move along the filament from one cell to the other. Here is an example of material transfer, while with Desulfobulbaceae, it is electrons that are trans- ported. Surely there is far more room at the bottom, and nanotechnologists can learn a lesson or two from such bacteria. D. BALASUBRAMANIAN [email protected] INGENUOUS NATURE: The conducting nanowire cable is not made of metal, alloy or other usual material, but of living biological cells. — PHOTO: S. THANTHONI Bacteria that line up to make a ‘live wire’ The bacteria form a long conducting nanowire cable to transport electrons and capture the oxygen at the surface for metabolic use SPEAKING OF SCIENCE SNAPSHOTS A new study using brevetoxin-2, a compound produced naturally by marine algae, stimulated nerve cell growth and plasticity in mouse neurons. Treatment for stroke may not be far off. Stroke recovery using marine algae product K. RAMESH BABU Two professors at the University of California, Riverside have developed a new method that doubles the efficiency of wireless networks and could have a large impact on the mobile Internet and wireless industries. Increasing efficiency of wireless networks M. KARUNAKARAN Using a regional climate model and the output of three global climate models, researchers at The City College of New York predict how climate change would change the face of Greenland over the next century. Climate change will alter Greenland’s face REUTERS Researchers have created a new artificial lens that is nearly identical to the natural lens of the human eye. This innovation may provide a natural performance in implantable lenses to replace damaged human eye lenses. New, more natural lens inspired by human eye S. SIVA SARAVANAN On November 13, the sun emitted a mid-level solar flare. Solar flares are powerful bursts of radiation, which can disturb the atmosphere in the layer where communications and Global Positioning System signals travel. Sun emits a mid-level flare on November 13 AFP NASA and British Antarctic Survey scientists have reported that marked changes to Antarctic sea ice drift caused by changing winds are responsible for observed increases in Antarctic sea ice cover in the past two decades. Why Antarctic sea ice cover has increased REUTERS T he results of the Phase III trial of the malaria vaccine RTS,S/AS01 are greatly disappointing. The ef- ficacy of the vaccine in pre- venting clinical and severe malaria in infants aged 6 to 12 weeks is much less than what was expected. In fact, the level of protection offered is nearly half of what was reported last year in older children (5 to 17 months). Vaccine efficacy The vaccine efficacy (in in- fants aged 6-12 weeks) was about 31 per cent in the case of clinical malaria and 37 per cent in the case of severe ma- laria. In the case of older chil- dren (5 to 17 months), reported last year, the protec- tion offered was nearly 56 per cent in the case of clinical ma- laria and about 47 per cent for severe malaria. The efficacy against severe malaria in both the groups combined was nearly 35 per cent. Totally, 6,537 infants were studied. The current data on infants is also lower than what was seen in the Phase II trial re- sults from three of the 11 cen- tres. The protection against clinical malaria was 61.6 per cent. According to Nature, nearly 60 per cent of clinical malaria cases were reported from just two of the 11 sites. The trial is being conducted in 11 centres across seven countries in Africa. What then could have caused a severe drop in the protection efficacy? One of the possibilities could be the severity of malaria transmis- sion. The Phase II results were from three centres that had only low to moderate ma- laria transmission. In the case of the Phase III, it also in- cluded centres that had high malaria transmission. The re- al implications of vaccine pro- tection in high malaria transmission areas will be clear when the complete data is analysed in 2014 after a 30- month follow-up. What is more disappointing is the drastic reduction in effi- cacy during the 12-month fol- low-up period. The efficacy was “higher at the beginning than at the end of the follow- up period” found the study, published a few days ago in The New England Journal of Medicine. If the protection efficacy does wane with time, several factors may make younger infants more vulner- able than older children, the paper suggests. Possible reasons What then could be the possible reasons for the dis- appointing protection levels seen? One could be the lower protection in areas that had higher malaria transmission. Another could be the differ- ence in immune response be- tween the infants and the older children included in the trial. Evidence favouring this was earlier seen during the trial. The co-administration of other vaccines along with the malaria vaccine could be another. Finally, the presence of maternal antibodies in in- fants could have played a role in protecting them (both the vaccine and control groups) from malaria, thereby reduc- ing the differences seen in the two groups. The vaccine has been de- veloped primarily for infants and children in sub-Saharan Africa. The reasons are obvi- ous: of the 216 million cases of malaria and 6,55,000 malar- ia-related deaths in 2010, a majority of deaths took place in African countries. Even as many newspapers went overboard last year based on results from the ol- der age group, the 2011 Edi- torial accompanying the paper in The New England Journal of Medicine explicit- ly stated: “there does not seem to be a clear scientific reason why this trial has been reported with less than half the efficacy results available.” The 2011 paper concluded with a rider that the “vaccine has the potential to have an important effect on the bur- den of malaria in young Afri- can children.” The rider was: the “vaccine efficacy among younger infants and the dura- tion of protection will be crit- ical to determining how this vaccine could be used effec- tively to control malaria.” Target 2014 In that sense, the latest re- sults do dampen the high spirits seen last year. The last word is yet to be pronounced. One has to wait till 2014 when the complete data is analysed and the outcome is known. Only then can it be said with any certainty if the vaccine will indeed be included for use in the African countries as per WHO recommenda- tions. WHO had taken the un- usual decision last year when it had “recommended” its use in the African countries as early as 2015. Malaria vaccine trial on African infants disappointing A drastic reduction in efficacy seen in the infants during the one-year follow-up period R. PRASAD DRASTIC DROP: The vaccine's malaria prevention efficacy in infants (6-12 weeks) is half of what was seen in older children (5-17 months). — PHOTO: AP I n the last week of October, the Mars rover Curiosity announced that there was no methane on Mars. The rover’s conclusion is only a prelimi- nary verdict, although it is al- ready controversial because of the implications of the gas’s discovery (or non-discovery). The presence of methane is an important sign to indicate that life may have existed in the planet’s past. The interest in the notion was increased when Curiosity found signs that water may have flowed in the past through Gale Crater, the immediate neighbour- hood of its landing spot, after finding sedimentary settlements. The rover’s Tunable Laser Spectrometer (TLS), which analysed a small sample of Martian air to come to the conclusion, had actually de- tected a few parts per billion of methane. However, recog- nising that the reading was too low to be significant, it sounded a “No”. In an email to this Corre- spondent, Adam Stevens, a member of the science team of the NOMAD instrument on the ExoMars Trace Gas Orbi- ter due to be launched in Ja- nuary 2016, stressed: “No orbital or ground-based de- tections have ever suggested atmospheric levels anywhere above 50 parts per billion, so we are not expecting to see anything above this level.” At the same time, he also noted that the 50 parts per billion (ppb) is not a global average. The previous detec- tions of methane found the gas localised in the Tharsis volcanic plateau, the Syrtis Major volcano, and the polar caps, locations the rover is not going to visit. What con- tinues to keep the scientists hopeful is that methane on Mars seems to get replen- ished by some geochemical or biological source. The TLS will also have an important role to play in the future. At some point, the in- strument will go into a higher sensitivity-operating mode and make measurements of higher significance by reduc- ing errors. It is pertinent to note that scientists still have an incom- plete understanding of Mars’s natural history. As Mr. Stevens noted: “While not finding methane would not rule out extinct or extant life, finding it would not necessar- ily imply that life exists or ex- isted either.” Apart from methane, there are very few “bulk” signatures of life that the Martian geog- raphy and atmosphere have to offer. Scientists are looking for small fossils, complex car- bon compounds and other hydrocarbon gases, amino acids, and specific minerals that could be suggestive of bi- ological processes. While Curiosity has some fixed long-term objectives, they are constantly adapted according to what the rover finds. Commenting on its plans, Mr. Stevens said, “Cu- riosity will move up Aeolis Mons, the mountain in the middle of Gale Crater, taking samples and analyses as it goes.” Curiosity is not the last chance to look more closely for methane in the near fu- ture. Development of the Ex- oMars Trace Gas Orbiter (TGO), with which Mr. Ste- vens is working, is under way. A collaboration between the European Space Agency and the Russian Federal Space Agency, the TGO is planned to deploy a stationary Lander that will map the sources of methane and other gases on Mars. Significance of Martian methane VASUDEVAN MUKUNTH S cientists in China said on Tuesday they had se- quenced the DNA of the wild bactrian camel, a threatened species with an extraordinary ability to survive in extreme conditions. The genetic code of Camel- us bactrianus ferus reveals 20,821 genes, many of them providing the metabolic tools to cope with days without food and water and a diet based on tough desert vegetation. Bactrian camels are de- scendants of even-toed ungu- lates which diverged from a common ancestor around 55- 60 million years ago, they found. The DNA book could shed light on the camel's ‘remarka- ble salt tolerance and unusu- al immune system,’ said the study, published in the jour- nal Nature Communications. Wild bactrian camels live in the deserts of northwest- ern China and southwestern Mongolia, where they endure fierce heat and bitter cold, aridity and sparse grazing. Camels consume eight times more salt than cattle or sheep and have twice the blood glucose levels of other ruminants, yet do not devel- op diabetes or hypertension. They also make unique dis- ease-fighting proteins called heavy-chain antibodies, which interest pharmaceuti- cal engineers. —AFP DNA study unravels secrets of bactrian camels led the study and presented the findings at a briefing. MRSA, or methicillin-re- sistant staphylococcus au- reus, is a drug-resistant bacterial infection, or superb- ug, and a serious public health problem. When outbreaks oc- cur in hospitals it can lead to the closure of whole wards with many people infected. The bug kills an estimated 19,000 people in the United States per year. Although rates of MRSA infection have come down significantly in Britain in recent years, it still presents a major threat with several hundred deaths a year and high hospital costs in- volved in managing infected patients. Julian Parkhill from Bri- tain's Sanger Institute, who also worked on the study, said R esearchers have used DNA sequencing for the first time to identify, analyse and put a halt to an infectious disease outbreak in a hospital. The success of the tech- nique, which used fast ge- nome sequencing technology to control an outbreak of the MRSA superbug on a baby ward, suggests it could be used to control hospital bugs, salmonella and E.coli infec- tions and diseases like tuber- culosis, scientists said. “What we have glimpsed through this pioneering study is a future in which new se- quencing methods will help us to identify, manage and stop hospital outbreaks,” said Nick Brown, an infection con- trol doctor at Addenbrooke's Hospital Cambridge, who co- there is a “real health and cost burden from hospital out- breaks” which could be signif- icantly reduced or eliminated if they were contained swiftly. In the study, staff at Ad- denbrooke's hospital using routine screening over a six month period found 12 pa- tients carrying MRSA. Be- cause they were only using standard tests, which provide limited information, the in- fection control team was not able to tell if the 12 were part of an outbreak, or were un- connected cases that did not present a threat. MRSA is a bug present in around one per cent of the population at any time, and does not always cause infection. Parkhill and Brown's team analysed MRSA samples from the 12 patients with DNA se- quencing technology and found that all the MRSA bac- teria were closely related, confirming an outbreak. By tracing relatives and other people who had recent links to the hospital, they also found the outbreak was more extensive than previously thought, with twice as many people carrying or infected with the MRSA strain. While this sequencing study was underway, the hos- pital's infection control team found a MRSA case in the spe- cial care baby unit - 64 days after the last MRSA patient had left. The team used advanced DNA sequencing to show in real time that this strain was also part of the same out- break, raising the possibility that a staff member was un- knowingly carrying and transmitting the MRSA strain. After screening 154 staff they found one carrying MRSA and, using DNA se- quencing, confirmed it was the strain linked to the out- break. The worker was quick- ly treated to eradicate the bug, and any further spread was stopped. The researchers, whose findings were published in the Lancet Infectious Diseas- es journal, say this kind of fast genome sequencing could eventually form the basis for regional or national infection surveillance programmes de- signed to nip infectious dis- ease outbreaks in the bud. — Reuters Genome sequencing halts superbug outbreak TH Chennai/ CITY SETA_01 User: cojmv 11-14-2012 23:46 Color: C M Y K
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SCIENCE & TECHNOLOGY
CMYK
CH-CH
18 THE HINDU THURSDAY, NOVEMBER 15, 2012CHENNAI
Poor adult health due to childhood abuse The psychological scars of childhood abuse can havelong-term negative physical effects, as well as emotionalones, well into adulthood.
Easing cancer symptoms by massageA new study shows that a type of ancient footmassage can help cancer patients manage theirsymptoms and perform daily tasks.
Necessity is the mother ofnatural selection. When
conditions become threaten-ing, maverick or mutantmembers of a group whichcan cope with the threat sur-vive and multiply. The latestexample is the discovery of aspecial type of bacteria in theocean, which join together toform a long conducting nano-wire cable to transport elec-trons and capture the oxygenat the surface for metabolicuse. This wire is not made ofmetal, alloy or other usualmaterial, but of living biolog-ical cells. The report by Dr.Christian Pfeiffer and othersin the 8 November 2012 issueof Nature is a live example ofthe Panchatantra tale whichteaches the value of cooper-ation between individuals towin over a problem.
All organisms gain energyfor living through metabo-lism. The vital step in theprocess is the burning or ox-idation of the food molecules.Chemists define oxidation as
the loss of electrons and re-duction as the gain of elec-trons. We burn our food bythe breathing of oxygen in theair. When we oxidize our foodand gain energy, the oxygenmolecule is reduced by ac-cepting or gaining electronsto make water, while the foodmolecule is oxidized by losingelectrons; this is not muchdifferent from burning petrolfor energy.
What if no oxygen?What about organisms that
live in places where there isno oxygen? They too metabo-lize their food through oxida-tion. But, rather than oxygen,they utilize whatever elec-tron-acceptor molecules areavailable in the environment.One such group lives in ma-rine sediments, below thesurface, and it use the sul-phates in the sediment as theelectron-acceptors for ‘burn-ing’ and gaining energy, anexample of making do withavailable resources. In the
process, however, the sul-phate gains electrons and isreduced all the way to hydro-gen sulphide (H2S), a poison-ous material. How then is thissulphide removed?
The problemLook at the problem. If H2S
can be oxidized to sulphur,the situation turns safer. Butin the process electrons areliberated and should be ac-cepted by a partner. If onlyoxygen at the surface can be
reached and the electronstransferred to it, we will haveH2S becoming S and the O2
reduced to H 2O. How doesone transfer the electronscentimetres away? It is nolonger a process within thecell where reactions happenwithin nanometres, and theoxidant and reductant mole-cules are in contact. What isneeded is an efficient method— an electrical cable or wirefor transporting the electronsfrom the sulphide to the ox-
ygen above. It is here that biology
springs an unexpected sur-prise. In the sedimental layerbeneath the marine surfacelives a class of anaerobic bac-teria called Desulfobulba-ceae, which Pfeffer andcolleagues find to denselypopulate the sediments. Andthese live not as individualsbut in groups strung togetheras long, multicellular fil-aments or rods, some as longas 1.5 centimetres. And thesefilaments reach out from thesulphide-rich sedimental lay-er to the aerobic top layer afew centimetres above, whichhas dissolved oxygen (fromthe air). These filaments thusconnect the anoxic layers tothe oxic layer. And what dothey do? They capture theelectrons generated when theH2S is oxidized to S at thebottom, and transport themall the way to the oxygen atthe top, which accepts themand generates water or H2O.In other words, the Desulfo-bulbaceae bacteria line up tomake a live wire.
The researchers conducteda series of experiments toshow how the filaments formand work. They layered thesedimental layer below in the
lab and covered is with theoverlying oxic sea water andstudied the process. As thesulphide oxidation happenedin the deeper anoxic layers,distinct change in the pH wasnoticed, confirming the proc-ess. And when they gently dis-turbed the layer, they foundthe 12-15 run long fibrous fil-aments entangled. Geneticanalysis of the filamentsshowed their identity as Des-ulfobulbaceae. It appears thatat least 40 million cells cometogether to assemble fil-aments of lengths as much as1.5 cm, showing that the bac-teria could span the length ofthe entire anoxic layer.
Liquid-filled layerElectron microscopy
showed that the cells wereconnected lengthwise, andeach cell had a liquid-filledlayer in the periplasmic spacebetween the outer and innercytoplasmic membranes.These liquid compartmentsformed ridges connecting theeach cell to its neighbour,suggesting electron transportoccurring through this fluidtubular structure coveredwith a continuous outermembrane along the filamentacting as the insulator — the
ancient precursor, if you will,of the electric cable of today.Hair-like appendages, calledpili, of some bacteria areknown to be electron trans-porters, but the whole cellacting so, and joining withothers to make a conductingwire is novel, and reported forthe first time.
Plenty of roomThe physicist Richard
Feynman famously remarkedthat there is plenty of room atthe bottom. Bacterial fil-aments acting as electric na-nowires is but one example.Some cyanobacteria calledAnabena, which are able to‘fix’ nitrogen, also form suchcontinuous periplasmic fil-aments. And when a fluores-cent protein was engineeredinto some its cells, the fluo-rescence was found to movealong the filament from onecell to the other. Here is anexample of material transfer,while with Desulfobulbaceae,it is electrons that are trans-ported. Surely there is farmore room at the bottom, andnanotechnologists can learn alesson or two from suchbacteria.
INGENUOUS NATURE: The conducting nanowire cableis not made of metal, alloy or other usual material,but of living biological cells. — PHOTO: S. THANTHONI
Bacteria that line up to make a ‘live wire’ The bacteria form a long conductingnanowire cable to transport electronsand capture the oxygen at thesurface for metabolic use
SPEAKING OF SCIENCE
SNAPSHOTS
A new study using brevetoxin-2, acompound produced naturally bymarine algae, stimulated nervecell growth and plasticity inmouse neurons. Treatment forstroke may not be far off.
Stroke recovery usingmarine algae product
K. RAMESH BABU
Two professors at the Universityof California, Riverside havedeveloped a new method thatdoubles the efficiency of wirelessnetworks and could have a largeimpact on the mobile Internet andwireless industries.
Increasing efficiency ofwireless networks
M. KARUNAKARAN
Using a regional climate modeland the output of three globalclimate models, researchers atThe City College of New Yorkpredict how climate change wouldchange the face of Greenland overthe next century.
Climate change willalter Greenland’s face
REUTERS
Researchers have created a newartificial lens that is nearlyidentical to the natural lens of thehuman eye. This innovation mayprovide a natural performance inimplantable lenses to replacedamaged human eye lenses.
New, more natural lensinspired by human eye
S. SIVA SARAVANAN
On November 13, the sun emitteda mid-level solar flare. Solar flaresare powerful bursts of radiation,which can disturb the atmospherein the layer wherecommunications and GlobalPositioning System signals travel.
Sun emits a mid-levelflare on November 13
AFP
NASA and British Antarctic Surveyscientists have reported thatmarked changes to Antarctic seaice drift caused by changing windsare responsible for observedincreases in Antarctic sea icecover in the past two decades.
Why Antarctic sea icecover has increased
REUTERS
The results of thePhase III trial of themalaria vaccineRTS,S/AS01 are
greatly disappointing. The ef-ficacy of the vaccine in pre-venting clinical and severemalaria in infants aged 6 to 12weeks is much less than whatwas expected. In fact, the levelof protection offered is nearlyhalf of what was reported lastyear in older children (5 to 17months).
Vaccine efficacyThe vaccine efficacy (in in-
fants aged 6-12 weeks) wasabout 31 per cent in the caseof clinical malaria and 37 percent in the case of severe ma-laria. In the case of older chil-dren (5 to 17 months),reported last year, the protec-tion offered was nearly 56 percent in the case of clinical ma-laria and about 47 per cent forsevere malaria. The efficacyagainst severe malaria in boththe groups combined wasnearly 35 per cent. Totally,6,537 infants were studied.
The current data on infantsis also lower than what wasseen in the Phase II trial re-sults from three of the 11 cen-tres. The protection againstclinical malaria was 61.6 percent. According to Nature,nearly 60 per cent of clinicalmalaria cases were reportedfrom just two of the 11 sites.The trial is being conductedin 11 centres across sevencountries in Africa.
What then could havecaused a severe drop in theprotection efficacy? One ofthe possibilities could be the
severity of malaria transmis-sion. The Phase II resultswere from three centres thathad only low to moderate ma-laria transmission. In the caseof the Phase III, it also in-cluded centres that had highmalaria transmission. The re-al implications of vaccine pro-tection in high malariatransmission areas will beclear when the complete datais analysed in 2014 after a 30-month follow-up.
What is more disappointingis the drastic reduction in effi-cacy during the 12-month fol-low-up period. The efficacy
was “higher at the beginningthan at the end of the follow-up period” found the study,published a few days ago inThe New England Journal ofMedicine. If the protectionefficacy does wane with time,several factors may makeyounger infants more vulner-able than older children, thepaper suggests.
Possible reasonsWhat then could be the
possible reasons for the dis-appointing protection levelsseen? One could be the lowerprotection in areas that had
higher malaria transmission.Another could be the differ-ence in immune response be-tween the infants and theolder children included in thetrial. Evidence favouring thiswas earlier seen during thetrial. The co-administrationof other vaccines along withthe malaria vaccine could beanother. Finally, the presenceof maternal antibodies in in-fants could have played a rolein protecting them (both thevaccine and control groups)from malaria, thereby reduc-ing the differences seen in thetwo groups.
The vaccine has been de-veloped primarily for infantsand children in sub-SaharanAfrica. The reasons are obvi-ous: of the 216 million cases ofmalaria and 6,55,000 malar-ia-related deaths in 2010, amajority of deaths took placein African countries.
Even as many newspaperswent overboard last yearbased on results from the ol-der age group, the 2011 Edi-torial accompanying thepaper in The New EnglandJournal of Medicine explicit-ly stated: “there does notseem to be a clear scientificreason why this trial has beenreported with less than halfthe efficacy results available.”
The 2011 paper concludedwith a rider that the “vaccinehas the potential to have animportant effect on the bur-den of malaria in young Afri-can children.” The rider was:the “vaccine efficacy amongyounger infants and the dura-tion of protection will be crit-ical to determining how thisvaccine could be used effec-tively to control malaria.”
Target 2014In that sense, the latest re-
sults do dampen the highspirits seen last year. The lastword is yet to be pronounced.One has to wait till 2014 whenthe complete data is analysedand the outcome is known.Only then can it be said withany certainty if the vaccinewill indeed be included foruse in the African countriesas per WHO recommenda-tions. WHO had taken the un-usual decision last year whenit had “recommended” its usein the African countries asearly as 2015.
Malaria vaccine trial on African infants disappointing A drastic reduction in efficacy seen in the infants during the one-year follow-up period
R. PRASAD
DRASTIC DROP: The vaccine's malaria prevention efficacy in infants (6-12 weeks)is half of what was seen in older children (5-17 months). — PHOTO: AP
In the last week of October,the Mars rover Curiosity
announced that there was nomethane on Mars. The rover’sconclusion is only a prelimi-nary verdict, although it is al-ready controversial becauseof the implications of thegas’s discovery (ornon-discovery).
The presence of methane isan important sign to indicatethat life may have existed inthe planet’s past. The interestin the notion was increasedwhen Curiosity found signsthat water may have flowed inthe past through Gale Crater,the immediate neighbour-hood of its landing spot, afterfinding sedimentarysettlements.
The rover’s Tunable LaserSpectrometer (TLS), whichanalysed a small sample ofMartian air to come to theconclusion, had actually de-tected a few parts per billionof methane. However, recog-nising that the reading wastoo low to be significant, itsounded a “No”.
In an email to this Corre-spondent, Adam Stevens, amember of the science teamof the NOMAD instrument onthe ExoMars Trace Gas Orbi-ter due to be launched in Ja-nuary 2016, stressed: “Noorbital or ground-based de-tections have ever suggestedatmospheric levels anywhereabove 50 parts per billion, sowe are not expecting to seeanything above this level.”
At the same time, he alsonoted that the 50 parts perbillion (ppb) is not a globalaverage. The previous detec-tions of methane found thegas localised in the Tharsisvolcanic plateau, the SyrtisMajor volcano, and the polarcaps, locations the rover isnot going to visit. What con-tinues to keep the scientists
hopeful is that methane onMars seems to get replen-ished by some geochemical orbiological source.
The TLS will also have animportant role to play in thefuture. At some point, the in-strument will go into a highersensitivity-operating modeand make measurements ofhigher significance by reduc-ing errors.
It is pertinent to note thatscientists still have an incom-plete understanding ofMars’s natural history. As Mr.Stevens noted: “While notfinding methane would notrule out extinct or extant life,finding it would not necessar-ily imply that life exists or ex-isted either.”
Apart from methane, thereare very few “bulk” signaturesof life that the Martian geog-raphy and atmosphere haveto offer. Scientists are lookingfor small fossils, complex car-bon compounds and otherhydrocarbon gases, aminoacids, and specific mineralsthat could be suggestive of bi-ological processes.
While Curiosity has somefixed long-term objectives,they are constantly adaptedaccording to what the roverfinds. Commenting on itsplans, Mr. Stevens said, “Cu-riosity will move up AeolisMons, the mountain in themiddle of Gale Crater, takingsamples and analyses as itgoes.”
Curiosity is not the lastchance to look more closelyfor methane in the near fu-ture. Development of the Ex-oMars Trace Gas Orbiter(TGO), with which Mr. Ste-vens is working, is under way.A collaboration between theEuropean Space Agency andthe Russian Federal SpaceAgency, the TGO is plannedto deploy a stationary Landerthat will map the sources ofmethane and other gases onMars.
Significance ofMartian methaneVASUDEVAN MUKUNTH
Scientists in China said onTuesday they had se-
quenced the DNA of the wildbactrian camel, a threatenedspecies with an extraordinaryability to survive in extremeconditions.
The genetic code of Camel-us bactrianus ferus reveals20,821 genes, many of themproviding the metabolic toolsto cope with days withoutfood and water and a dietbased on tough desertvegetation.
Bactrian camels are de-scendants of even-toed ungu-lates which diverged from acommon ancestor around 55-60 million years ago, theyfound.
The DNA book could shed
light on the camel's ‘remarka-ble salt tolerance and unusu-al immune system,’ said thestudy, published in the jour-nal Nature Communications.
Wild bactrian camels livein the deserts of northwest-ern China and southwesternMongolia, where they endurefierce heat and bitter cold,aridity and sparse grazing.
Camels consume eighttimes more salt than cattle orsheep and have twice theblood glucose levels of otherruminants, yet do not devel-op diabetes or hypertension.
They also make unique dis-ease-fighting proteins calledheavy-chain antibodies,which interest pharmaceuti-cal engineers. —AFP
DNA study unravelssecrets of bactrian camels led the study and presented
the findings at a briefing.MRSA, or methicillin-re-
sistant staphylococcus au-reus, is a drug-resistantbacterial infection, or superb-ug, and a serious public healthproblem. When outbreaks oc-cur in hospitals it can lead tothe closure of whole wardswith many people infected.
The bug kills an estimated19,000 people in the UnitedStates per year. Althoughrates of MRSA infection havecome down significantly inBritain in recent years, it stillpresents a major threat withseveral hundred deaths a yearand high hospital costs in-volved in managing infectedpatients.
Julian Parkhill from Bri-tain's Sanger Institute, whoalso worked on the study, said
Researchers have usedDNA sequencing for the
first time to identify, analyseand put a halt to an infectiousdisease outbreak in ahospital.
The success of the tech-nique, which used fast ge-nome sequencing technologyto control an outbreak of theMRSA superbug on a babyward, suggests it could beused to control hospital bugs,salmonella and E.coli infec-tions and diseases like tuber-culosis, scientists said.
“What we have glimpsedthrough this pioneering studyis a future in which new se-quencing methods will helpus to identify, manage andstop hospital outbreaks,” saidNick Brown, an infection con-trol doctor at Addenbrooke'sHospital Cambridge, who co-
there is a “real health and costburden from hospital out-breaks” which could be signif-icantly reduced or eliminatedif they were containedswiftly.
In the study, staff at Ad-denbrooke's hospital usingroutine screening over a sixmonth period found 12 pa-tients carrying MRSA. Be-cause they were only usingstandard tests, which providelimited information, the in-fection control team was notable to tell if the 12 were partof an outbreak, or were un-connected cases that did notpresent a threat.
MRSA is a bug present inaround one per cent of thepopulation at any time, anddoes not always causeinfection.
Parkhill and Brown's team
analysed MRSA samples fromthe 12 patients with DNA se-quencing technology andfound that all the MRSA bac-teria were closely related,confirming an outbreak.
By tracing relatives andother people who had recentlinks to the hospital, they alsofound the outbreak was moreextensive than previouslythought, with twice as manypeople carrying or infectedwith the MRSA strain.
While this sequencingstudy was underway, the hos-pital's infection control teamfound a MRSA case in the spe-cial care baby unit - 64 daysafter the last MRSA patienthad left.
The team used advancedDNA sequencing to show inreal time that this strain wasalso part of the same out-
break, raising the possibilitythat a staff member was un-knowingly carrying andtransmitting the MRSAstrain.
After screening 154 staffthey found one carryingMRSA and, using DNA se-quencing, confirmed it wasthe strain linked to the out-break. The worker was quick-ly treated to eradicate thebug, and any further spreadwas stopped.
The researchers, whosefindings were published inthe Lancet Infectious Diseas-es journal, say this kind of fastgenome sequencing couldeventually form the basis forregional or national infectionsurveillance programmes de-signed to nip infectious dis-ease outbreaks in the bud. —Reuters
Genome sequencing halts superbug outbreak
TH Chennai/ CITY SETA_01 User: cojmv 11-14-2012 23:46 Color: CMYK
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