SCIENCE TRIBUNE Thursday, April 4, 2002, Chandigarh, India

Uses of DNA fingerprintingUses of DNA fingerprinting
Rajeev Goel
n unusual outcome of the recombinant DNA technology is the "DNA fingerprinting" or DNA profiling". DNA fingerprinting is based on the principle that the genetic makeup of every person is different from the others but is unique and distinctive to an individual. 

Ultra-small computers on the way
n entirely new generation of powerful ultra-small computers and electronics devices is one step closer, according to researchers at the University of California, Berkeley. 


  • Wind-up cell phone

  • Anger makes people cooperate

  • Slimmer batteries

  • Artificial hand  with intelligence

  • Japanese robot  set to clean up



Uses of DNA fingerprinting
Rajeev Goel

An unusual outcome of the recombinant DNA technology is the "DNA fingerprinting" or DNA profiling". DNA fingerprinting is based on the principle that the genetic makeup of every person is different from the others but is unique and distinctive to an individual. DNA ID or genetic fingerprinting is the only definite, positive and permanent identification method of a person as one’s DNA neither changes during one’s lifetime nor it can be altered by any method. Other identification methods like picture ID, social security numbers (as in USA) and fingerprints/thumb impressions have their limitations. The photograph may fade or has to be updated frequently, and fingerprints can smear or can be altered by surgery, or even difficult to acquire as in case of a baby or a child.


It is interesting to know that fingerprints were first introduced in year 1860 in India by a British administrator, William Herschel, as a proof of identity to pay pensions to illiterate ex-soldiers. Later on, English biologist Francis Galton extensively worked on the classification of the fingerprints for their complete use in crime investigations and his classic book Fingerprints was published in 1892. A murder case in Argentina was solved in 1892 based on his classification. This classification system was further changed by Edward Henry and is still in use all over the world. However, the problem with the fingerprints is that the two individuals can have the same fingerprints although the chances are very-very low. There has been, therefore, a need to have a type of ID, which is conclusive in exclusion. Dr Allec Jeffreys of the UK accomplished this objective in 1985 by exploiting the individual specific variation (polymorphism) in the arrangement of bases (building blocks of DNA) in the DNA. This was given the name of DNA fingerprinting or DNA profiling which has now become a widely used courtroom tool.

Schematic drawing showing DNA fingerprints (profile) used in a paternity dispute. RFLP patterns (DNA fragments or bands) of father (A), mother (B) & two children (C&D) are shown here. The profile shows that the child C has inherited one DNA band from each parent but child D has one band inherited from the mother and an unrecognised band different from the father. A is therefore not the father of the child D (see text).

DNA fingerprinting tests in India are mainly carried out at the Centre for Cellular & Molecular Biology (CCMB), Hyderabad. The DNA samples to carry out DNA fingerprinting in case of crimes are obtained from the trace amount of blood, semen or vaginal swab, buccal smear, hairs or skin cells. The DNA is recovered from these cells. The "chemical scissors" widely known as restriction enzymes are then used to cut the extremely long DNA, at specific points, into smaller fragments. Every one of us has fixed points where the restriction enzyme acts, that in turn give rise to specific pattern of the DNA fragments. These fragments are specific not only in terms of their numbers but also in term of their lengths.

The DNA being a charged molecule is further subjected to electric current in a jelly like substance (gel electrophoresis) to separate the fragments produced by restriction enzymes. The number and position of the bands formed on the gel is the "actual fingerprints" of that DNA sample and is compared with the control samples taken from the suspects. This determines whether the DNA samples are from the same person, related people or non-related people. The DNA pattern so generated is called as Restriction Fragment Length Polymorphisms (RFLPs). In very rare instances two individuals might have the same pattern of fragments when one restriction enzyme is used. This problem is overcome by using a combination of restriction enzymes.


The practical applications of DNA fingerprinting are numerous. DNA fingerprints are used in pedigree analysis and establishing paternity and maternity. The patterns are so specific that half of the DNA fragments (RFLPs) will be common with those of the father and half with those of the mother (see figure). This is because the person inherits his or her RPLP pattern from his or her parents. It is interesting to know that a parental RFLP pattern can be reconstructed even if only the children’s RFLP patterns are available. DNA profiling is nowadays used by the immigration authorities in establishing family relationship. The technique has been shown to have a considerable potential in forensics. The RFLP patterns are also employed in establishing the identity of a homicide victim either from the DNA found as an evidence or from the body itself.

The genetic fingerprints can be used for personal identification though the methods such as dental record, social security number or picture ID are still the methods of choice.

DNA fingerprints can help in diagnosing the inherited disorders like cystic fibrosis, hemophilia, Huntington’s disease, familial Alzheimer’s, thalassemia, sickle cell anemia and many others in the prenatal and newborn babies. The mutation in the particular gene in these genetic disorders changes the RFLP pattern. The use of DNA fingerprints in prenatal diagnosis can help the parents to take decision concerning the affected fetus. Moreover, the parents can use their own DNA profiles to understand the risk of having an affected child as well. DNA fingerprinting is so powerful that even the blood stained clothing from Abraham Lincoln has been analysed for evidence of genetic disorder called Marfan’s Syndrome. DNA profiling is not restricted to humans alone. It is also applicable to animals for livestock breeding and in plants for authentication of seeds and germplasm.


DNA fingerprinting is highly technical. There are chances of human errors at various steps during the processing of DNA. Nobody would like to see, because of these errors, an innocent person going to jail and the guilty person walking free, or a biological mother deprived of her legal right to custody of her child. There is a need to have stringent quality control checks in DNA fingerprinting labs worldwide. Nonetheless, DNA fingerprinting has proved to be a valuable tool not only in the field of medicine or forensics but also in veterinary and agriculture.


Ultra-small computers on the way

An entirely new generation of powerful ultra-small computers and electronics devices is one step closer, according to researchers at the University of California, Berkeley.

There work and that of a Swedish team is reported in the February issue of the peer-reviewed journal Nano Letters, published by the American Chemical Society, world’s largest scientific society.

The two groups have succeeded independently in making lattices that they say will for the first time enable nanowires to be constructed with otherwise incompatiable materials. Such mixed bundles are essential to making electronic and other devices on an increasingly smaller scale.

“This is a major advancement in the field of one-dimensional nanostructure research. The impact could be tremendous,” predicts Peidong Yang, at the University of California and a faculty scientist at the Lawrence Berkeley National Laboratory.

A related paper by Swedish researchers also appears in the February issue of Nano Letters. Based on the findings of both research groups, tiny components known as nanowires, that meld together a variety of materials, could soon be routinely and cheaply built using little more than a special mixture of gases deposited on a foundation material.

The report by the US team of three researchers details how they successfully fabricated “Superlattice” nanowire, so named because the nanowire’s cylinder-shaped nanoscopic bundle interweaves substances with different compositions and properties.

As a result, well-defined junctions and interfaces with potentially important functioinalities were incorporated within individual nanowires.

Those working in the field of Nanotechnology have long sought such a means to bring together materials on the nanoscopic scale that otherwise would be structurally incompatiable.

Like conventional builders — who rely on a mix of concrete, wood, metals, plastics and paints to construct comfortable and energy-efficient homes and offices — nanoengineers, by mixing and matching different elements, hope to create entirely new classes of nanoscale products or systems that would revolutionise everything from energy production to manufacturing and assembly.

In the field of electronics and optics, mastery of these nanoscale “heterostructures” should lead to devices too small to see with the naked eye, but equal to or better than today’s hand-size electronics.

Today’s personal computers rely on a series of small junctions that connect components that have properties necessary for proper functioning. Given the laws of physics and real-world manufacturing demands, radically scaling down such functionality is difficult. The research findings in California and Sweden promise to make ultra-small-scale device practical. 



Wind-up cell phone

Wind-up cell phoneTired of having your cell-phone battery go dead just when you need it most? FreeCharge is a half-pound, hand-cranked generator that you can attach to your cell phone and turn for 30 seconds to generate enough juice for five minutes of talk time.

The first version will work on most Motorola phones; the next ones will power other makers' phones.

This is the third in a series of windup electronic devices originally designed for use in developing nations. The first two—the Freeplay radio and flashlight—have been surprise hits in the USA. It will sell for $65.To learn more:

Anger makes people cooperate

Swiss researchers have made an unsettling discovery, while trying to fathom what makes people cooperate, that it is anger and not love, affection or even blatant self-interest that binds human societies together.

Traditional explanations, such as kinship and reciprocal altruism, rely on genetic relationships or self-interest. These work for animals, but fail for humans because people cooperate with strangers they never meet again, and when the pay-off is not obvious.

Such cooperation can be explained if punishment of freeloaders or “free-riders” — those who do not contribute to a group but benefit from it — is taken into account, a report in New Scientist said.

However, in real life, punishment is rarely without cost to the punisher. To provide an answer as to why should someone punish a free-rider, Ernst Fehr, an economist at the University of Zurich in Switzerland says it is because of emotionally driven altruism. PTI

Slimmer batteries

To keep pace with smaller and more powerful transceiver and memory components used in IT and medical applications, researchers have developed thinner, lighter and more flexible power storing devices for these products.

Rechargeable lithium-polymer-based thin-film batteries represent one solution, as developed by the Microelectronics Alliance, which comprises five Fraunhofer institutes. This involves specially developed low-power components and a power management system — electronic circuits monitor charge and discharge cycles and indicate the charging level of the battery.

“Flexible thin-film batteries of just a tenth of a millimetre in thickness required for smart cards and other flat storage media are no longer a utopian vision,” states Jochen Schulz of the Fraunhofer Institute for Silicate Research ISC, illustrating the trend toward miniaturisation, a report in Fraunhofer Gesellschaft said.

“The gap between the two electrodes is correspondingly small, which leads to problems — at the required high current densities, or charge relative to area, liquid electrolytes heat up during charging and discharging. This can generate a build up of pressure in the battery, causing it to expand and in the worst case explode.”

As a pre-emptive measure, researchers at the ISC employ organically modified polymer materials. The molecular structure of the patented ORMOCER enhances both thermal and mechanical stability, vital for ensuring the flexibility of the thin-film battery. In the near future, researchers aim to be able to dispense with liquid, electrolyte altogether.

At the same time, the Fraunhofer Institute for Chemical Technology ICT is working on solutions to another problem caused by the close proximity of the electrodes. PTI

Artificial hand with intelligence

A lightweight “intelligent hand” has been devised by two United kingdom cybernetic engineers who have spent years devising the mechanical replacement to develop a prosthesis that looks and behaves as a human hand.

The principle behind the device, developed by Peter Kyberd of Oxford’s Orthopaedic Engineering Centre and Southampton University’s Paul Chapel, is to use microprocessor to undertake the functions that control the finger, while the user gives only overall commands to open, close and hold objects, using simple signals.

The prosthetic fingers curl continuously from open to closed and the thumb follows the same line as the natural hand. Each fingers has force and slip sensors in its tip, a report in London Press Service said.

If the object being held slips, this generates vibrations that are detected by the sensors and the hand automatically tightens its grip until the sliding stops.

The sensors are sensitive enough for the hand to pick up and hold an egg. The controller circuit board is housed in the hand which is covered by a silicone glove cast from a real hand.

Some hands are already being used by patients attending Oxford’s Limb Centre. One device is a hybrid handcomplete with a wrist and elbow produced by the Bio-engineering unit of Edinburgh’s Prince Margaret Rose Hospital. PTI

Japanese robot set to clean up

Doing the housework could soon be a relaxing experience, thanks to the world’s first robotic vacuum cleaner. Developed by the Japanese electronics giant Matsushita, the robot is slightly bigger than a football and has the intelligence to avoid falling downstairs or crashing into walls.

Fitted with 50 sonic and infrared sensors, it can work for up to an hour on a single battery charge after using its sensors to measure the size of each room that needs to be cleaned.

“We have long been tackling the automation of domestic chores,” said Matsushita director Yoshitaka Hayashi. The firm, which owns Panasonic, has spent around $ 1.4 million developing the robotic cleaner. Hayashi said: “Robots will some day guard against fires and burglary in homes while people are asleep.”

In a demonstration at Matsushita’s Osaka headquarters last week, the machine inched a path around a mock-up living room, avoiding cabinets and furniture, and slowed down over dusty areas. Matsushita said robots would be used in various homes in a trial in May before a full retail launch is announced.

Consumers can already buy a range of “personal robots’ at a cost of around $ 2,800. Most perform basic functions, such as delivering food and drinks or fetching items. Robotics engineer Hans Moravec said: “There was a lot of optimism in the beginning when robots first appeared on the scene. But some of us began to realise there was a major miscalculation in building robots — and that had to do with the belief that complicated programming was involved. Observer