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What Animals Have Been Cloned?

June 27, 2011 by rfcamat Leave a Comment

Dolly
Dolly, the first mammal to be cloned (Wikimedia Image)
It was in 1996 the world woke up to the news of a sheep named Dolly created through a technique called cloning. Dolly was a carbon copy of another sheep and this started a debate on should scientists be acting like God and producing animals and humans on order.

Cloning is done by removal of DNA from an ovum and replacing it with the DNA of an adult animal. The fertilized ovum is implanted in a womb and an identical or clone animal can be produced. However, the technique is fraught with risks. The cloned animals have been known to carry genetic disorders and have a comparatively short lifespans.

Not many people know that Dolly was not the first animal to have been cloned by scientists. Way back in 1958, scientist John Gurdon claimed to have cloned a frog by using intact nuclei from somatic cells of a Xenopus tadpole. In 1963, Chinese embryologist Tong Dizhou created the first fish clone by inserting the DNA from a male Asian carp into the egg of a female Asian carp. Dizhou went on to create the first interspecies carp clone by inserting Asian carp DNA into a European crucian carp in 1973. In 1986, a mouse named Masha became the first mammal to be cloned using embryo cell.

However, Dolly is still regarded as the most significant achievement in the history of cloning because she was the first mammal to have been cloned using adult cells. Before her, cells extracted from an embryo were being used to create a clone. The success of the Dolly experiment also resulted in a fierce competition among various research groups who started cloning one animal after another.

Scientists at the University of Hawaii created Cumulina, the first mouse clone using adult cells, within one year of Dolly’s birth in 1997.[ad#co-1]

The first cloned calf was also born in the same year and later kept at Minnesota Zoo Education Center. In 1999, Dr Xiangzhong (Jerry) Yang cloned a Holstein heifer named Amy by using ear skin cells from a high-merit cow named Aspen at the University of Connecticut. He followed it up by three additional clones, Betty, Cathy and Daisy in the same year.

The year 1999 saw birth of Second Chance, a Brahman bull which was cloned from a celebrity bull Chance at the Texas A&M University. The research centre was also successful in cloning a Black Angus bull named 86 Squared 15 using cells from his donor, Bull 86, which were frozen in 2000. Just like its parent, the cloned bull also exhibited natural resistance to tuberculosis, brucellosis, and other diseases which can be transmitted to meat.

Five Scottish piglets were created using cloning technique in 2000. In 2001, cloning was done to save Gaur, an endangered species of wild cattle. It was born from a surrogate domestic cow mother at the Trans Ova Genetics in Sioux Center, Iowa, USA. However, the clone died within two days.

The year 2001 saw intensified activity in the field of cloning with birth of two female jersey cows Millie and Emma at the University of Tennessee. They were the first cows to be produced using standard cell-culturing techniques.

In the same year a cat called CopyCat was cloned at Texas A&M University. Though the DNAs of both the clone and the host were same, they had different personalities. Around 10 more Jersey cows were cloned at the University of Tennessee in 2002 while the first commercially cloned cat, Little Nicky, was created by Genetic Savings & Clone in 2004.

In 2003, a Boer goat was cloned at Texas A&M University. In the same year, three male mules were cloned for the first time while a rabbit was also cloned in France.

The year also saw the birth of a first cloned deer named Dewey at Texas A&M University while in 2005 South Korean scientist Hwang Woo-Suk cloned the first dog, Snuppy, an afghan hound. South Korean scientists went on to clone sniffer dogs.

Anatolian Grey bull called Efe was cloned in Turkey along with world’s first buffalo calf through the “hand guided cloning technique” in the year 2009. Next year, the first Spanish fighting bull was cloned by Spanish scientists.

The cloning experiments on animals are still on around the world while there are some unverified claims of human cloning too.[ad#afterpost]

Filed Under: Biology, Genetics

Is Tongue Rolling Genetic?

June 27, 2011 by rfcamat Leave a Comment

Tongue rolling
Tongue rolling (Rochelle/Flickr)

Can you roll your tongue into shape of a test tube? Do you get dry ear wax? Do you have cleft chin? Can you wiggle your ears? When you clasp your hands which thumb lands up on the top? These questions may seem innocuous and unwarranted but a whole lot of researchers are scratching their heads on these puzzles which many believe is linked to genetics.

So can you really roll your tongue into shape of a tube? Not many people can but then they do have friends who can and this difference some researchers say is because of genetics. Biology students are taught that tongue rolling is the simplest way to explain inherited genes. Those who can roll their tongues have inherited the gene from their tongue-rolling parents while those who can’t also have parents who can’t roll their tongues. You have got your genes from your parents and even if one of the parents has the tongue-rolling gene, you will be able to roll your tongue.

It’s not so easy to explain

The explanation is not as simple as it is made it out to be and your biology teacher might be wrong after all because there are people who can roll their tongues while their parents can’t. Another research study done by Matlock in 1952 concluded that identical twins don’t always share the tongue-rolling trait. Identical twins are known to have identical DNAs and hence should also share the ability to roll the tongue if they have same genes.  In 1975, another researcher demonstrated that identical twins are no more likely to share tongue-rolling than are fraternal twins. This gives birth to the idea that environment is also a major factor. Both the twins might be having the gene but it is not expressed in one of them due to absence of an environmental trigger.

The environmental trigger theory has also found takers in several other conditions like autoimmune disorders. People are known to be predisposed to them but these disorders are manifested in only those who encounter particular environmental triggers stress, pollution or specific disorders.[ad#co-1]

Another theory regarding tongue rolling is that there might be another gene called modifier gene which is controlling the expression of tongue rolling gene. So there can be parents who possess the gene to roll their tongues but still they can’t roll them because the modifier gene in them is off. Now their child can have the ability to roll the tongue if they modifier gene is not passed on.

All these explanations may seem confusing but that’s not the end of the whole story. Tomorrow some new research may prove that all the above propositions are wrong and there is some new factor that defines tongue rolling. Meanwhile, surveys done by biologists have put forth interesting data related to tongue rolling. It was found that in Spain 67 per cent of females can roll their tongues compared to just 64 per cent of the male population. However, Spanish men are better at wiggling their ears. Around 20 per cent of them can wiggle their ears as compared to 10 per cent of women. Another Iranian researcher found that north England does not have many people who can roll their tongues and this, he believes, is because of genetic intermingling with the Scandinavians.

Whatever the final verdict be, it’s clear that if you can roll your tongue, genetics are involved in this ability of yours. However, to what extent the power of genetics works in this scenario is not yet known. So, the picture is out but the contours are still being finalized.[ad#afterpost]

Filed Under: Biology, Genetics

Famous Foreign Biologists and their Significant Contributions

June 27, 2011 by rfcamat Leave a Comment

Biology defines the life in and around us. Not only has the subject helped us understand ourselves better but the knowledge of reproduction, physiology, adaptation, disease and other aspects of the body has saved several lives, thereby promoting the cause of mankind.

Here we talk about famous foreign biologists who have left their footprints in this field.

Aristotle

Aristotle
Aristotle (Wikimedia Image)

Known as the great Greek philosopher, scientist and the teacher of Alexander, Aristotle is often called the father of biology. Born in 384 BC, he set up a framework of knowledge which served as the foundation for past and present science and philosophy. Since Alexander was his pupil, Aristotle was able to define plant and animal species from all parts of his vast empire. He wrote around 400 treatises including the ones written on motion of animals, gait of animals, parts of animals and generation of animals. Though these books had a tinge of error and myth, they were a good starting point for further research in the field of biology. One of Aristotle’s students Theophrastus compiled the most important works on botany written in that era.

Charles Darwin

Charles_Robert_Darwin
Charles Robert Darwin (Wikimedia Image)

Born in early 19th century England, Charles Darwin is one of the most famous foreign biologists instrumental in progress of mankind with some of his time-tested theories on evolution and natural selection.He first served in 1831 as an unpaid naturalist in the Beagle, a ship that travelled around the world for five years. The trip helped Darwin observed the biological and geological environments of different parts of the world. During his stay at the Galápagos Islands, he got convinced about the theory of evolution of the species. Later, he went on to propose that natural selection is the engine of evolution. To support his theory, Darwin did several tests and found a supporter in Alfred Russell Wallace, a young naturalist who was also working on same ideas. In 1859 Darwin published ‘The Origin of Species’, which has been instrumental in changing the world.[ad#co-1]

 

Louis Pasteur

Louis Pasteur
Louis Pasteur (Wikinedia Image)

Pasteur has done a great service to humanity with his work in the field of medical science. Born in 1822, he was the one who gave us the germ theory and explained how infectious diseases affect us. He proposed changes in hospital practices and the improved sanitation standards helped save billions of lives. Pasteur also discovered the fact that fermentations are made by microbes which is why the term ‘pasteurisation’ came into being as an indication to killing of dangerous microbes in certain food items. He also developed vaccines against anthrax and rabies. When he died in 1895, Pasteur was given the state burial as a national hero.

 

Alexander Fleming

Alex Fleming
Alex Fleming (Wikimedia Image)

If Pasteur taught us about infections, Alexander Fleming introduced as to the world of antibiotics. Born in 1881, he was known for the discovery of penicillin, the world’s first antibiotic which helped saved millions of lives. Fleming observed the growth of Staphylococcus bacteria which was inhibited by a Penicillium mold that had accidentally contaminated the culture plate thus giving an idea that it can be used to help deal with bacterial infection in humans. At the end of World War II, a lot of hurt soldiers of the allied troops saved their lives thanks to penicillin. Fleming also discovered lysozyme, an antibacterial enzyme present in mucous secretions.

In 1945, he won the Nobel Prize for physiology and medicine along with Chain and Florey who had carried further research related to efficacy of Penicillin.

Erwin Chargaff

Erwin Chargaff
Erwin Chargaff (Wikimedia Image)

American biochemist and author Erwin Chargaff also worked in the same field and discovered the key facts necessary to determine the basic chemical structure of DNA.  Chargaff’s findings, along with those of Rosalind Franklin’s X-ray diffraction studies of DNA, strongly suggested that base-pairing existed within DNA.

 

 

 

 

Rita Levi-Montalcini

Rita Levi Montalcini
Rita Levi Montalcini (Wikimedia Image)

Born in Italy in 1909, Rita Levi-Montalcini was the one to discover nerve-growth factor (NGF), a protein instrumental in survival and growth of brain neurons. The discovery has helped in development of several medications to treat brain disorders.

 

 

 

 

 

Werner Arber

Werner Arber
Werner Arber (Wikimedia Image)

Swiss microbiologist and geneticist, Werner Arber was instrumental in discovery of restriction endonucleases, which led to the development of recombinant DNA technology.

 

 

 

 

 

 

More Famous Biologists

  • Sir Alec Jeffreys
  • Sir James Watson
  • Linus Pauling
  • Barbara McClintock

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Filed Under: Biology

The 12 Cranial Nerves and Their Functions

June 21, 2011 by rfcamat Leave a Comment

Inferior view of the brain and brain stem showing cranial nerves.
Inferior view of the brain and brain stem showing cranial nerves. (Wikimedia Commons Image)

Cranial nerves in humans consist of twelve pairs of nerves that emerge from the ventral side of the brain. The first two pairs arise from the cerebrum while the other ten pairs emanate from the brainstem. As in the case of spinal nerves which are named based on their origin from the spinal cord, cranial nerves derived their name from their close association with the cranium. The holes or openings in the skull serve as their passage to reach their targets throughout the human body. Some of these nerves send messages from our senses while other cranial nerves control muscle movement, glandular secretions and our internal organs.

A cranial nerve may also be classified as sensory, motor or both according to their mode of signal transmission. Motor nerves carry impulses from the brain to target tissues such as muscles and glandular tissues while sensory nerves transmit impulses from sensory organs to the brain. The table below shows an overview of the cranial nerves, their modality and function.

Table 1.

CRANIAL NERVES MODALITY FUNCTION
I. Olfactory Sensory Smell
II. Optic Sensory Vision
III. Oculomotor Motor Eye movement and pupil constriction
IV. Trochlear Motor Eye movement
V. Trigeminal Both Controls muscles for mastication (motor); somatosensory output from face, head and neck
VI. Abducens Motor Eye movement
VII. Facial Both Controls muscles for facial expression (motor); sensory input from anterior 2/3 of tongue (taste) and ear (tympanic membrane)
VIII. Vestibulocochlear Sensory Hearing and balance
IX. Glossopharyngeal Both Controls some muscle for swallowing (motor); sensory input from posterior 1/3 of tongue, tonsil and pharynx
X. Vagus Both For motor, sensory and autonomic functioning of the viscera (e.g. digestion, glandular secretion, heart rate)
XI. Spinal Accessory Motor Controls muscles used in head movement
XII. Hypoglossal Motor Controls muscles of tongue except palatoglossal

 

I. Olfactory Nerve

This nerve functions primarily for the sense of smell. Its name is derived from the Latin words ‘olfactare’, which means to sniff at, and ‘olfacere’, which means to smell. Among all the cranial nerves, this is the only one capable of self-renewal since it has the property to regenerate continually through adulthood. Also, aside from being the smallest nerve, the olfactory nerve doesn’t branch out into left and right entities. Instead, it consists of a collection of sensory rootlets that extend from the olfactory epithelium to the olfactory bulb as it passes through the numerous openings of the cribriform plate in the ethmoid bone. When a person inhales, molecules of air attach themselves to the sensory parts of the olfactory nerve which are located in the olfactory mucosa at the upper part of the nasal cavity. As these nerve endings become stimulated, electrical activity is generated and is transmitted to the olfactory bulb. The cells in the olfactory bulb in turn relay the electrical signal to the brain through the olfactory tract.

II. Optic Nerve

During embryonic development, the optic nerve arises from the diencephalon, thus considered a part of the central nervous system. As with other CNS components, optic nerves are covered with Myelin sheath rather than Schwann cells and are wrapped by meninges. Unlike the olfactory nerve, optic nerves are incapable of regeneration which increases the risk of permanent blindness when severed.

Optic nerve conveys visual information from the retina to the brain. When light reaches the retina, stimulation of the photoreceptors (rods and cones) occurs which triggers the production of electrical impulses. These are relayed to the bipolar cells which contain the optic nerve endings. The bipolar cells in turn transmit the electrical impulses to the CNS via the optic nerve. The optic nerves enter the CNS at the optic chiasm where they become the optic tract. From there, the electric signal is transduced to the lateral geniculate nucleus of each thalamus before going to the visual centers of the brain for interpretation.

III. Oculomotor Nerve

Oculomotor nerve has two components: 1. Somatic motor or general somatic efferent which controls muscles responsible for precise eye movement for visual tracking and fixation on an object and 2. Visceral motor or general visceral efferent provides parasympathetic innervation of the constrictor pupillae and ciliary muscles of the eye which regulate light accommodation by controlling pupil constriction.

The somatic motor component is further divided into inferior and superior divisions. The inferior division innervates the medial rectus, inferior rectus and inferior oblique muscles while the superior division supplies the levator palpebrae superioris and superior rectus muscle. The table below shows a summary of the function of the eye muscles controlled by the somatic motor component.

Table2.

Eye Muscles Primary action Secondary action Tertiary action
Medial rectus Adduction – —
Inferior oblique Extorsion Elevation Abduction
Inferior rectus Depression Extortion Adduction
Superior rectus Elevation Intortion Adduction
Levator palpebrae superioris Controls movement of the upper eyelid

 

Table adapted from http://www.med.yale.edu/caim/cnerves/cn3/cn3_3.html

The other two eye muscles not included in Table2 are the Superior oblique (Intorsion, Depression, Abduction) and Lateral rectus (Abduction) which are controlled by the Trochlear Nerve (IV) and the Abducens Nerve (VI) respectively.

IV. Trochlear Nerve

This nerve has only a somatic motor component which controls one eye muscle – the Superior oblique. As mentioned above, superior oblique carries out three different functions: intorsion, depression and adbuction.

Though this nerve only supplies one eye muscle, it has several characteristics that distinguish it from the other cranial nerves.

1.This is the only nerve that exit the brain dorsally.

2.This is the only nerve that decussate or cross which makes the nerve fibers supply the superior oblique muscle on the side opposite their origin.

3.This has the longest intracranial route.

4.This has the smallest number of neurons.

V. Trigeminal Nerve

The trigeminal nerve, as the name implies, is consists of three large branches: Ophthalmic and Maxillary which are both sensory, and the Mandibular branch which has both motor and sensory functions. The Ophthalmic branch innervates the forehead and the eye while the Maxillary branch supplies the cheeks. The Mandibular branch on the other hand controls the lower jaw and lower portion of the face. Since this nerve has both sensory and motor functions, it is responsible for sensing facial touch, pain, and temperature and controlling the mandibular muscles during mastication.

The three branches meet in an area called the Gasserion ganglion. The fused branches extends backwards to the brainstem, inserting itself into the pons. Inside the brainstem, the signals that pass through the trigeminal nerve arrive at a structure called trigeminal nerve nucleus. From there, the information is sent to the cerebral cortex where perception of the sensation is achieved.

VI. Abducens

This nerve has only a motor component which innervate the lateral rectus muscle of the eye. To make a lateral movement, inputs from the higher centers of the brain in the form of electrical impulses synapse at the lateral gaze center. From there, the signal travels through the longitudinal fasciculus to reach the abducens nucleus, which then sends the message to the lateral rectus muscle via CN VI , causing the muscle to be abducted.

VII. Facial Nerve

The facial nerve is a mixed nerve having both the sensory and motor components. It has approximately 10,000 neurons in which 70% of these are myelinated and control facial expressions. The other 30% are somatosensory and secretomotor in function. The table below shows the nature and function of the facial nerve.

Table3.

Branchial motor
(special visceral efferent)
The largest component of the facial nerve 

 

Supplies voluntary control of the posterior belly of the digastric, stylohyoid and stapedius muscles as well as muscles involve in facial expression such as the buccinator, occipitalis and platysma muscles

Visceral motor
(general visceral efferent)
Comprise the parasympathetic constituent of CN VII 

 

Provides parasympathetic control over the submandibular, sublingual, and lacrimal glands

 

Innervates the mucous membranes of the nasopharynx and hard and soft palates

Special sensory
(special afferent)
Consists of fibers that transmit sensation of taste from the anterior 2/3 of the tongue as well as from the hard and soft palates
General sensory
(general somatic afferent)
Conveys sensory information from the skin of the concha of the auricle and from a small area of skin behind the ear 

 

Acts as a supplement to the Mandibular component of the Trigeminal Nerve to provide sensation at the wall of the acoustic meatus and the outer surface of the tympanic membrane

 

VIII. Vestibulocochlear Nerve

This is a sensory nerve that consists of two components – vestibular and cochlear. The vestibular nerve detects head and body motion while the cochlear nerve detects sound. Thus, the vestibulocochlear nerve functions for hearing and balance. Balance is achieved by conveying information to the vestibular component of the CN VIII which are done by the semicircular canal and the otolithic organ. The former detects angular acceleration while the latter detects linear acceleration.

For us to hear and recognize the sounds around us, the cochleat component of the CN VIII should be stimulated. This happens when sound waves collected by the outer ear travel through the ear canal and cause vibrations of the ear drum. The vibration of the ear drum moves the bones of the middle ear which in turn pass the vibrations to the fluid-filled cochlea. As the fluid inside the cochlea moves, it causes the cilia to vibrate and stimulate the sensory cochlear nerve. When stimulated, the nerve sends signal to the area of the brain where the signals are processed into the sound we hear.[ad#co-1]

IX. Glossopharyngeal Nerve

As the name implies, CN IX innervates the tongue and the pharynx and has both the motor and sensory components. The functions of each component are summarized in the table below.

Table4.

Branchial motor
(special visceral efferent)
Provides voluntary control of the stylopharyngeus muscle which elevates the pharynx during swallowing and speech
Visceral motor
(general visceral efferent)
Parasympathetic component which innervates the parotid gland and the smooth muscle of the pharynx, larynx, and viscera of the thorax and abdomen
Visceral sensory
(general visceral afferent)
Controls the baroreceptors of the carotid sinus and chemoreceptors of the carotid body
General sensory
(general somatic afferent)
Transmits sensation of pain, temperature, and touch from the skin of the external ear, internal surface of the tympanic membrane, the walls of the upper pharynx, and the posterior 1/3 of the tongue
Special sensory
(special afferent)
Carries sensation of taste from the posterior one-third of the tongue

X. Vagus Nerve

The term ‘Vagus’ is a Latin word which means ‘wandering’. Vagus nerve fits its name since it wanders from the brainstem and extend to organs found in the neck, chest and abdomen. Table 5 summarizes the vagus nerve’s components and their respective functions.

Table5.

Brancial motor
(special visceral efferent)
Supplies voluntary control to the striated muscle of the pharynx and larynx (except for the stylopharyngeus muscle and the tensor veli palatini muscle) as well as the palatoglossus muscle of the tongue
Visceral motor
(general visceral efferent)
Parasympathetic control of the smooth muscle and glands of the pharynx, larynx, and thoracic and abdominal viscera down to the splenic flexure resulting to increased GI tract secretion and motility, higher bronchiolar secretions and bronchoconstriction in the lungs and slower heart rate.
Visceral sensory
(general visceral afferent)
Transmits sensory information from the larynx, esophagus, trachea, abdominal and thoracic viscera, aortic arch and the aortic bodies
General sensory
(general somatic afferent)
Carries sensation of pain, temperature, and touch from from the larynx and pharynx as well as information from the skin of the back of the ear and external auditory meatus, parts of the external surface of the tympanic membrane
Special sensory
(special afferent)
Transmits sensation of taste from the epiglottic region

 

XI. Spinal Accessory Nerve

This is a motor nerve consisting of cranial and spinal parts that control muscles of the neck and shoulders to move the head. The cranial part (special visceral efferent) innervates muscles of the pharynx and larynx while the spinal part (special visceral efferent) controls the trapezius and sternocleidomastoid muscles. The trapezius muscle moves the scapula, acts as a support for the arm, assists in breathing, keeps the head in position and produces bending and rotational head movement. The sternocleidomastoid muscle on the other hand flexes the neck and turns the head obliquely.

XII. Hypoglossal Nerve

As indicated in its name, this nerve innervates the muscles found below (hypo) the tongue hence consists only of the motor component. It provides voluntarily control over the three out of four extrinsic muscles of the tongue which include genioglossus, styloglossus, and hyoglossus. Genioglossus muscle is responsible for protruding (or sticking out) the tongue while styloglossus draws up the sides of the tongue to aid in swallowing. The hyoglossus muscle on the other hand retracts and depresses the tongue for chewing and speech.[ad#afterpost]

Filed Under: Biology, Health, Medicine

Ethical Issues Associated With Human Cloning

June 18, 2011 by rfcamat Leave a Comment

Dolly's remains are exhibited at the Museum of Scotland.
Dolly's remains are exhibited at the Museum of Scotland. (Wikimedia Image)

In the movie “The Sixth Day”, a clone of Adam Gibson (Arnold Schwarzenegger) takes over his family and professional role forcing the original character to prove his authenticity in the year 2015.

The movie could not be far from reality especially when experiments to produce human clones are being done clandestinely across the globe.

Cloning debate gained momentum since Dolly, the first cloned mammal, walked over the earth in 1996. The birth of Dolly opened the possibility that humans can be also be cloned using the same technique. Today, scientific cloning is yet to go mainstream mainly because it’s a difficult and expensive procedure and till now the clones produced have not been able to live long enough.

While animal cloning is quite acceptable in the society, we are yet to accept the fact that some time in future human clones will be greeting us in neighborhood parks.

Human cloning is possible through various methods. Embryo cloning, one of the methods, involves production of identical twins artificially. A few cells extracted from a fertilized embryo can be induced to develop into a duplicate embryo having DNA identical to its parent embryo. This technique has been used successfully on animals.

Another method is through removal of DNA from an ovum and replacing it with the DNA of an adult. The fertilized ovum is implanted in a womb and an identical or human clone can be produced. However, studies done on animals show that this technique can result in severe genetic defects in the newborn. Due to these side effects, this technique is banned in several countries but an Italian embryologist claimed to have developed a human clone through this procedure.

Several ethical issues of human cloning crop up through the years. Some people would like to have a clone to have a biological insurance to extract organs from in case their original ones fail or damaged. In this scenario, the existence of a clone just to save the original human being or to act as a replacement for him strongly questions human morality.

While a human clone’s right to identity is jeopardized, questions are raised on his right to inheritance, choice of a life partner, and other crucial life matters.

The safety of cloned humans is also questioned. While most attempts to clone mammals have failed, several of the clones born suffer from debilitating conditions and die prematurely. Moreover, we still don’t know how cloning impacts the brain and other vital organs in the body.

Therapeutic cloning, another technique, differs from reproductive cloning in a way that no offspring is given birth to. Only stem cells are extracted from the pre-embryo for the purpose of developing organs or tissues that can replace the damaged organs of the original DNA donor. The process eliminates the need to wait for the right donor and since the DNA is exactly the same, there are no complications in organ transplantation..

However, many decry such a procedure since the human embryo is destroyed in the extraction of stem cells. They feel that since embryo is equivalent to a human being, he should have rights equal to those of normal humans and killing him just to save the life of another person is simply unjust.

The stem cell proponents, however, claim that the stage at which the stem cells are being extracted is a very nascent stage and the embryo does not have brain to have awareness of the self and also lacks a thought process. They feel it can only be termed as human when it’s aware of the environment and has sensory capabilities, organs and limbs.

Time will tell whether humans are going to accept human cloning technology or not. But many scientists are unstoppable in developing perfect techniques on human cloning and stem cell production.


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Filed Under: Biology, Genetics

The Advantages and Disadvantages of Genetically Modified Food

June 18, 2011 by rfcamat Leave a Comment

Btcornafrica
Kenyans examining insect-resistant transgenic Bt corn (Wikimedia Commons)

There is no love more sincere than the love for food. Food is  a uniting factor among different cultures since everybody likes to taste and enjoy exotic cuisines from around the world. This is also one of the reasons why the issue of genetically modified (GM) food is generating intense debate because we are what we eat. GM food includes crops, fruits and vegetables which are created by combining quality genes of various species and hence have better nutritional and productive value. The difference between this technique and traditional breeding is that latter occurs only between related species and hence is safe whereas there is no final word on safety of mixing genes of unrelated species.

Both sides of GM food debate are equally vociferous in expressing their opinions. While the pro lobby talks about how the GM crop can give a larger and better yield even in inhabitable conditions, the critics talk about risk to health and environment due to genetic alterations and exploitation of the poor by food corporates. Here we have a deeper look at the issue.

Advantages of Genetically Modified Food

Supporters of GM food crops are mostly relying on scientific data claiming that these crops yield much larger quantity and hence can be the solution to the problem of world hunger. The ability of GM crops to be cultivated even in areas with poor soil and harsh weather conditions is one of the advantages of genetically modified food. Another plus point is that the food produced is higher in nutritional value and can also taste better than the traditional variety. GM crops have inbuilt resistance against pests, insects and diseases allowing them to produce higher yield. The proponents are also claiming that genetic modification can even make certain food free of common allergies. This can be done by removing the genes that express the allergens or substances that trigger allergic reactions.

The GM foods are also capable of staying ripe for long hence there is lesser problem of spoilage. This can be done by adding a gene in the crop that expresses an organic compound that will extend the shelf life of the food.

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Disadvantages of Genetically Modified Food

While the pros of GM food may seem rewarding, the critics claim that they don’t hold water. First of all, they counter the technique itself by putting forth the argument that scientists still don’t know much about the genetics GM crops. They may identify quality genes but where to introduce them so as not to disturb the natural expression is still unclear. In fact, this lack of knowledge can lead to faulty interventions and irrepressible side effects. Traditional breeding has natural checks and balances due to breeding between related species but these are missing in GM food crops.

The hope that GM food can be an answer to the world hunger is another faux pause because they claim that millions of people sleep with empty stomach not because of lack of food but because of improper distribution. Millions of tons of food are wasted every month around the world because they do not reach the needy. Financial, infrastructural and political reasons rather than less production are responsible for the large number of hungry people across the globe.

The GM food may be having inbuilt resistance to common pests and insects but these organisms are known to mutate according to changes in their environment for survival. Thus, disease-resistant crops will only give rise to superbugs which will be more difficult to destroy.

Another big issue with GM crops is that they cross-pollinate with nearby normal crops and lead to ecological issues. Furthermore, if GM crops contain vaccines and antibiotics, human health is in peril as it would contribute to the development of resistance genes to human viruses and bacteria that we normally kill using vaccines and antibiotics.

Opponents assert that GM crops are patented by big biotechnology corporations that make sure that the harvested grains/fruits are not viable source of seeds to force farmers to buy costly seeds every time they want to cultivate the land.

Tests to validate the risks of GM crops are very expensive that most corporations avoid testing each and every food item. This increases the chances of unsafe food getting served to people.

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Filed Under: Biology, Genetics

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