The History of Nepal is characterized by its isolated position in the Himalayas and its two dominant neighbors, India and China. Even though it was independent through most of its history, it was split in three from the 15th to 18th century. It was united as a monarchy, and experienced a failed struggle for democracy in the 20th century. Since the 1990s, the country is in civil strife.
Toponymy
The toponym "Nepal" may derive from the Sanskrit nipalaya, which means "at the foot of the mountains" or "abode at the foot," a reference to its location in relation to the Himalayas. Thus, it may be an Eastern equivalent of the European toponym "Piedmont." It has also been suggested that the name comes from the Tibetan niyampal, which means "holy land". A third theory suggests that Nepal came from the word NE which means wool and PAL means tented house. Long time ago, Nepal used to produce a lot of wool and the houses were used to store the wool, hence the word NE-PAL
Ancient history
Neolithic tools found in the Kathmandu Valley indicate that people have been living in the Himalayan region for at least 9,000 years. Documented references reach back to the first millennium BCE, when ancient Indian epics such as the Mahabharata mention the Kiratas, the inhabitants of Nepal. It appears that people who were probably of Tibeto-Burman ethnicity lived in Nepal 2,500 years ago. Ramayana, which refers to the era before Mahabharat, states Mithila, which is currently known as Janakpur in Nepal, as the birth place of goddess Sita. Also, the presence of historical sites, e.g., Valmik ashram, indicates the presence of Aryan culture in Nepal at that period.
Birth of Buddhism
Indo-Aryan tribes began arriving around 1500 BCE from the northwest. Around 1000 BCE, small kingdoms and confederations of clans arose in the region. One of the earliest confederations was that of the Shakya clan, whose capital was Kapilavastu, near the present-day border with India. One of its princes was Siddharta Gautama (563–483 BCE), who renounced his royalty to lead an ascetic life and came to be known as the Buddha ("the enlightened one"). By 260 BCE, most of northern India was ruled by the Maurya Empire. Although not all of Nepal was under Maurya rule, there is evidence of at least the influence of Ashoka the Great—the ruler of the Maurya Empire from 273 to 232 BCE and a convert to Buddhism—have been found in the Kathmandu Valley. In the fourth century CE, the area fell under the Gupta Empire. Though all of Nepal wasn't under the direct control of the Guptas, they have had an influence on its culture.
Licchavi
Between about 400 and 750 AD, Nepal's present capital Kathmandu was ruled by the Licchavi kingdom. Archaeological evidence for this period mainly consists of stonework inscriptions, reckoned on two separate, consecutive eras. The former, Åšaka era has an epoch corresponding to 78 AD, whereas the latter Aṃshuvarmā or Mānadeva 2 era reckons from 576.
Whilst most such inscriptions list the dates and commissioners of stonework construction, some communicate royal edicts, religious mantras or historical notes. It is through the corroboration of local myths with such evidence that a people prior to the Licchavi have been identified, known as the Kirata. Of these people very little is known.
The Licchavi rulers arranged for the documentation of information on politics, society, and the economy in the region. Most of the Licchavi records—written in Sanskrit—are deeds reporting donations to religious foundations, predominantly Hindu temples; and the last such record was added in 733.
The Licchavi dynasty went into decline in the late eighth century and was followed by a Newari era, from 879, although the extent of their control over the entire country is uncertain. By the late 11th century, southern Nepal came under the influence of the Chalukaya Empire of southern India. Under the Chalukayas, Nepal's religious establishment changed as the kings patronised Hinduism instead of the prevailing Buddhism.
12th century
By the early 12th century, leaders were emerging whose names ended with the Sanskrit suffix malla ("wrestler"). Arimalla was the first king of this dynasty, which was initially marked by upheaval before the kings consolidated their power over the next 200 years.
Three medieval kingdoms
Hindu temples in Patan, the capital one of the three medieval kingdoms
Thirteenth-century Nepal was occasionally pillaged by the Delhi Sultanate of northern India, and was marked by increased militarisation. By the late 14th century much of the country came under the rule of the king Jayasthitimalla, who managed to unite most of the fragmented power bases. This unity was short-lived: in 1482 the kingdom was carved into three: Kathmandu, Patan, and Bhadgaon.
Gorkha rule
Modern Nepal was created in the latter half of the 18th century when Prithvi Narayan Shah, the ruler of the small principality of Gorkha, formed a unified country from a number of independent hill states. The country was frequently called the Gorkha Kingdom. It is a misconception that the Gurkhas took their name from the Gorkha region of Nepal. The region was given its name after the Gurkhas had established their control of these areas. Gurkha, also spelt as Gorkha, are people from Nepal who take their name from the legendary eighth century Hindu warrior-saint Guru Gorakhnath. Gurkhas claim descent from the Hindu Rajputs and Brahmins of Northern India, who entered modern Nepal from the west.
After decades of rivalry between the medieval kingdoms, Prithvi Narayan Shah dedicated himself at an early age to the conquest of the Kathmandu valley and the creation of a single state, which he achieved in 1768. Between 1717 and 1733, the Nepalese in the west and Bhutanese in the east attacked Sikkim many times, culminating with the destruction of the capital Rabdentse by the Nepalese. The Sikkim king fled to Tibet. After Shah's death, the Shah dynasty began to expand their kingdom into India. Between 1788 and 1791, Nepal invaded Tibet and robbed Tashilhunpo Monastery of Shigatse. Alarmed, the Chinese emperor Qianlong dispatched a sizeable army that forced the Nepalese to retreat and pay heavy repatriations.
After 1800, the heirs of Prithvi Narayan Shah proved unable to maintain firm political control over Nepal. A period of internal turmoil followed. Rivalry between Nepal and the British East India Company over the annexation of minor states bordering Nepal eventually led to the Anglo-Nepalese War (1814–16), in which Nepal suffered a complete rout. The Treaty of Sugauli was signed in 1816, ceding parts of the Terrai and Sikkim to the British in exchange for Nepalese autonomy.
Rana Administration
Rani (Queen) of Nepal surrounded by her Ladies-in-Waiting, 1920
Factionalism among the royal family led to a period of instability after the war. In 1846, Queen Rajendralakshmi plotted to overthrow Jang Bahadur, a fast-rising military leader who was presenting a threat to her power. The plot was uncovered and the queen had several hundred princes and chieftains executed after an armed clash between military personnel and administrators loyal to the queen. This came to be known as the Kot Massacre. However, Bahadur emerged victorious and founded the Rana lineage. The king was made a titular figure, and the post of Prime Minister was made powerful and hereditary. The Rana regime, a tightly centralized autocracy, pursued a policy of isolating Nepal from external influences. This policy helped Nepal maintain its national independence during the colonial era, but it also impeded the country's economic development.
The Ranas were staunchly pro-British, and assisted the British during the Sepoy Rebellion in 1857, and later in both World Wars.
20th century
In 1923 Britain and Nepal formally signed an agreement of friendship, in which Nepal's independence was recognised by the British.
Democratic Reform
In the late 1940s. Meanwhile, with the annexation of Tibet by the Chinese in 1950, India faced the prospect of an expansive military power operating under a radically different political philosophy on its long northern borders, and was thus keen to avoid instability in Nepal. Forced to act, India sponsored both King Tribhuvan as Nepal's new ruler in 1951, and a new government, mostly comprising the Nepali Congress Party. After years of power wrangling between Tribhuvan's son, King Mahendra and the government, Mahendra dissolved the democratic experiment in 1960. In 1962 he declared that a "partyless" panchayat system would govern Nepal.
Popular dissatisfaction against the family rule of the Ranas had started emerging from among the few educated people, who had been taught in various Indian school and colleges, and from within the Ranas, many of whom were marginalised within the Ruling Rana hierarchy. Many of these Nepalese in exile had actively taken part in the Indian Independence struggle and wanted to liberate Nepal as well from the internal autocratic occupation. The political parties like The Prajaparishad and The Nepali Rastriya Congress were already formed in exile by the patriotic minded people who wanted to stage both the military and popular political movement in Nepal to overthrow the autocratic Rana Regime. Among the prominent martyrs to die for the cause executed at the hands of the Ranas were Dharma Bhakta Mathema, Shukraraj Shastri, Gangalal Shrestha and Dasharath Chand. This culminated in 1950, King Tribhuvan, a direct descendant of Prithvi Narayan Shah, fled his "palace prison" to newly independent India, touching off an armed revolt against the Rana administration. This allowed the return of the Shah family to power and, eventually, the appointment of a non-Rana as prime minister. A period of quasiconstitutional rule followed, during which the monarch, assisted by the leaders of fledgling political parties, governed the country. During the 1950s, efforts were made to frame a constitution for Nepal that would establish a representative form of government, based on a British model.
In early 1959, King Mahendra issued a new constitution, and the first democratic elections for a national assembly were held. The Nepali Congress Party, a moderate socialist group, gained a substantial victory in the election. Its leader, B.P. Koirala, formed a government and served as prime minister.
Democratic Failure
Declaring parliamentary democracy a failure 18 months later, King Mahendra dismissed the Koirala government and promulgated a new constitution on December 16, 1962. The new constitution established a "partyless" system of panchayats (councils) which King Mahendra considered to be a democratic form of government closer to Nepalese traditions. As a pyramidal structure progressing from village assemblies to a Rastriya Panchayat (National Parliament), the panchayat system enshrined the absolute power of the monarchy and kept the King as head of state with sole authority over all governmental institutions, including the Cabinet (Council of Ministers) and the Parliament. One-state-one-language became the national policy and all other langauages suffered at the cost of the official language, "Nepali", which is the king's language.
King Mahendra was succeeded by his 27 year-old son, King Birendra, in 1972. Amid student demonstrations and anti-regime activities in 1979, King Birendra called for a national referendum to decide on the nature of Nepal's government--either the continuation of the panchayat system with democratic reforms or the establishment of a multiparty system. The referendum was held in May 1980, and the panchayat system won a narrow victory. The king carried out the promised reforms, including selection of the prime minister by the Rastriya Panchayat.
People in rural areas had expected that their interests would be better represented after the adoption of parliamentary democracy in 1990. Jana Andolan forced the monarchy to accept constitutional reforms and to establish a multiparty parliament. The Nepali Congress won 110 of the 205 seats and formed the first government in 32 years. In May 1991, Nepal held its first election in nearly 50 years.
In 1992, in a situation of economic crisis and chaos, with spiralling prices as a result of implementation of changes in policy of the new Congress government, the radical left stepped up their political agitation. A Joint People's Agitation Committee was set up by the various groups.A general strike was called for April 6.
Violent incidents began to occur on the evening ahead of the strike. The Joint People's Agitation Committee had called for a 30-minute 'lights out' in the capital, and violent erupted outside Bir Hospital when activists tried to enforce the 'lights out'. At dawn on April 6, clashes between strike activists and police outside a police station in Pulchok (Patan) left two activists dead.
Later in the day, a mass rally of the Agitation Committee at Tundikhel in the capital Kathmandu was attacked by police forces. As a result riots broke out, and the Nepal Telecommunications building was set on fire. Police opened fire at the crowd, killing several persons. The Human Rights Organisation of Nepal estimated that 14 people, including several on-lookers, had been killed in police firing.
When promised land reforms failed to appear, people in some districts started to organize to enact their own land reform, and to gain some power over their lives in the face of usurious landlords. However, this movement was repressed by the Nepali government, in "Operation Romeo" and "Operation Kilo Sera II" which took the lives of many of the leading activists of the struggle. As a result, many witnesses to this repression became radicalized.
Nepalese Civil War
In February 1996, one of the Maoist parties started a bid to replace the parliamentary monarchy with a so-called people's new democratic republic, through a Maoist revolutionary strategy known as the people's war, which has led to the Nepalese Civil War. Led by Dr. Baburam Bhattarai and Pushpa Kamal Dahal (also known as "Prachanda"), the insurgency began in five districts in Nepal: Rolpa, Rukum, Jajarkot, Gorkha, and Sindhuli. The Maoists declared the existence of a provisional "people's government" at the district level in several locations. At one point, 70% of Nepal's countryside was under Maoist rule.
2001-2006
In June 2001 Crown Prince Dipendra went on a shooting-spree assassinating 11 members of the royal family including King Birendra and Queen Aishwarya before shooting himself. Due to his survival he temporarily became king before dying of his wounds resulting in Prince Gyanendra (Birendra's brother) inheriting the throne. Meanwhile, the Maoist rebellion escalated, and in October 2002 the king temporarily deposed the government and took complete control of it. A week later he reappointed another government, but the country is still very unstable because of the civil war with the Maoists, the various political factions, the king's attempts to take more control of the government and worries about the competence of Gyanendra's son and heir, Prince Paras.
In the face of unstable governments and a Maoist siege on the Kathmandu Valley in August 2004, popular support for the monarchy began to wane. On 2005-02-01, Gyanendra dismissed the entire government and assumed full executive powers, declaring a "state of emergency" to quash the Maoist movement. Politicians were placed under house arrest, phone and internet lines were cut, and freedom of the press was severely curtailed. The king's new regime made little progress in his stated aim to suppress the insurgents.
King Gyanendra took control once again on February 1, 2005. Municipal elections in February 2006 were described by the European Union as "a backward step for democracy", as the major parties boycotted the election and some candidates were forced to run for office by the army. In April 2006 strikes and street protests in Kathmandu forced the king to reinstate the parliament. A seven-party coalition resumed control of the government and stripped the king of most of his powers. At present, the future of monarchy remains in question, and it is unclear whether the Maoist parties, which part of the interim government, will hold true to their cease fire. As of 15 January 2007 Nepal is governed by an unicameral legislature under an interim constitution.
Monday, April 2, 2007
Sunday, April 1, 2007
.jpg)
Thursday, March 1, 2007
European Society for Biomaterials
European Society for Biomaterials
European Society for Biomaterials is a non-profit organization that encourages research and spread of information regarding research and uses of biomaterials. Founded in 1976. It has approximately 600 members in 27 countries. It organizes an annual meeting where recent developments mainly about academic research are presented.
Objectives of European society for biomaterials:
Its objectives are (from ESB Statute article 4):
* To encourage, foster, promote and develop research, progress and information concerning the science of biomaterials, as well as to promote, initiate, sustain and bring to a satisfactory conclusion research with others and programs of development and information in this particular field.
· To collaborate with other associations and bodies whose efforts are directed at the same objectives and whose interest are allied with or are similar to those of the Society itself.
· To promote the propagation of scientific information through publications and meetings.
· To co-operate with other scientific organizations, governmental and private bodies, both national and international, in order to establish specifications and standards for biomaterials in general.
· To encourage progress in the field of biomaterials in all its aspects, including research, teaching and clinical applications, as well as to foster any other activity pertinent thereto.
The Society can award PhDs with a European Biomaterials and Tissue Engineering Doctoral Award (EBTEDA) if they fulfill some requirements such has having done their training in at least two European countries and can discuss their field of research in at least two European languages.
The George Winter Award
It is established to recognize, encourage and stimulate outstanding research contributions to the field of biomaterials. It is handed out on the Society Annual Meeting. George Winter was the first President of the Society.
The Jean Leray Award
This award is established to recognize, encourage and stimulate outstanding research contributions to the field of biomaterials by young scientists, which is not more than 40 years old at the end of the nomination period and has finished a stint as a postdoctoral research fellow within 8 years. Jean Leray was the first Vice-President of the Society.
Any member of the European Society for Biomaterials in good standing may nominate candidates for the George Winter and the Jean Leray awards. The nominee needs neither to be a member of the European Society for Biomaterials nor a citizen of a European country. Posthumous nominations are not considered.
As a way to encourage the presence of young researchers at the conference the Society also hands out:
Student Travel Awards
The Society supports student participation at their conferences through the travel award scheme. Applications for consideration must be submitted at the time of registration.
Student Prizes
The Society award prizes for the best student poster and oral presentation made during any particular Society conference.
Journal
The ESB home journal is the Journal of Materials Science: Materials in Medicine (ISSN 0957-4530) published by Springer. Each year a special issue of selected contributions to the annual conference is published.
Annual Conference
The annual meeting rotates between the European countries which has organization members. It comprises of oral and poster presentations of novel results, and plenary session of invited speakers to describe general trends and developments. Special work groups and work shops are featured. Both academia and companies uses the event to expose themselves, their products, services and job opportunities. The annual conference sports a Young Scientist Forum to discuss education and teaching within the field of biomaterials.
Retrieved from "http://en.wikipedia.org/wiki/European_Society_for_Biomaterials"
just taking first steps in blogging
European Society for Biomaterials is a non-profit organization that encourages research and spread of information regarding research and uses of biomaterials. Founded in 1976. It has approximately 600 members in 27 countries. It organizes an annual meeting where recent developments mainly about academic research are presented.
Objectives of European society for biomaterials:
Its objectives are (from ESB Statute article 4):
* To encourage, foster, promote and develop research, progress and information concerning the science of biomaterials, as well as to promote, initiate, sustain and bring to a satisfactory conclusion research with others and programs of development and information in this particular field.
· To collaborate with other associations and bodies whose efforts are directed at the same objectives and whose interest are allied with or are similar to those of the Society itself.
· To promote the propagation of scientific information through publications and meetings.
· To co-operate with other scientific organizations, governmental and private bodies, both national and international, in order to establish specifications and standards for biomaterials in general.
· To encourage progress in the field of biomaterials in all its aspects, including research, teaching and clinical applications, as well as to foster any other activity pertinent thereto.
The Society can award PhDs with a European Biomaterials and Tissue Engineering Doctoral Award (EBTEDA) if they fulfill some requirements such has having done their training in at least two European countries and can discuss their field of research in at least two European languages.
The George Winter Award
It is established to recognize, encourage and stimulate outstanding research contributions to the field of biomaterials. It is handed out on the Society Annual Meeting. George Winter was the first President of the Society.
The Jean Leray Award
This award is established to recognize, encourage and stimulate outstanding research contributions to the field of biomaterials by young scientists, which is not more than 40 years old at the end of the nomination period and has finished a stint as a postdoctoral research fellow within 8 years. Jean Leray was the first Vice-President of the Society.
Any member of the European Society for Biomaterials in good standing may nominate candidates for the George Winter and the Jean Leray awards. The nominee needs neither to be a member of the European Society for Biomaterials nor a citizen of a European country. Posthumous nominations are not considered.
As a way to encourage the presence of young researchers at the conference the Society also hands out:
Student Travel Awards
The Society supports student participation at their conferences through the travel award scheme. Applications for consideration must be submitted at the time of registration.
Student Prizes
The Society award prizes for the best student poster and oral presentation made during any particular Society conference.
Journal
The ESB home journal is the Journal of Materials Science: Materials in Medicine (ISSN 0957-4530) published by Springer. Each year a special issue of selected contributions to the annual conference is published.
Annual Conference
The annual meeting rotates between the European countries which has organization members. It comprises of oral and poster presentations of novel results, and plenary session of invited speakers to describe general trends and developments. Special work groups and work shops are featured. Both academia and companies uses the event to expose themselves, their products, services and job opportunities. The annual conference sports a Young Scientist Forum to discuss education and teaching within the field of biomaterials.
Retrieved from "http://en.wikipedia.org/wiki/European_Society_for_Biomaterials"
just taking first steps in blogging
Cloning
Cloning
Cloning is the process of creating an identical copy of something. In Biology, it collectively refers to processes used to create copies of DNA fragments (Molecular Cloning), Cells (Genetic Cloning), or organisms. The term also encompasses situations, whereby organisms reproduce asexually, but in common parlance refers to intentionally created copies of organisms.
Etymology
The term clone is derived from κλων, the Greek word for "twig", referring to the process, whereby a new plant can be created from a twig. In horticulture, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o”.Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively.
Molecular cloning
Molecular cloning refers to the procedure of isolating a defined DNA sequence and obtaining multiple copies of it in vivo. Cloning is frequently employed to amplify DNA fragments containing genes, but it can be used to amplify any DNA sequence such as promoters, non-coding sequences and randomly fragmented DNA. It is utilized in a wide array of biological experiments and practical applications such as large scale protein production. Occasionally, the term cloning is misleadingly used to refer to the identification of the chromosomal location of a gene associated with a particular phenotype of interest, such as in positional cloning. In practice, localization of the gene to a chromosome or genomic region does not necessarily enable one to isolate or amplify the relevant genomic sequence.
In essence, in order to amplify any DNA sequence in a living organism that sequence must be linked to an origin of replication, a sequence element capable of directing the propagation of its self and any linked sequence. In practice, however, a number of other features are desired and a variety of specialized cloning vectors exist that allow protein expression, tagging, single stranded RNA and DNA production and a host of other manipulations.
Cloning of any DNA fragment essentially involves four steps: fragmentation, ligation, transfection, and screening/selection. Although these steps are invariable among cloning procedures a number of alternative routes can be selected, these are summarized as a ‘cloning strategy’.
Initially, the DNA of interest needs to be isolated to provide a relevant DNA segment of suitable size. Subsequently, a ligation procedure is employed whereby the amplified fragment is inserted into a vector. The vector (which is frequently circular) is linearised by means of restriction enzymes, and incubated with the fragment of interest under appropriate conditions with an enzyme called DNA ligase. Following ligation the vector with the insert of interest is transfected into cells. A number of alternative techniques are available, such as chemical sensitivation of cells, electroporation and biolistics. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation. Modern cloning vectors include selectable antibiotic resistance markers, which allow only cells in which the vector has been transfected, too grow. Additionally, the cloning vectors may contain colour selection markers which provide blue/white screening (α-factor complementation) on X-gal medium. Nevertheless, these selection steps do not absolutely guarantee that the DNA insert is present in the cells obtained. Further investigation of the resulting colonies is required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and/or DNA sequencing.
Cellular cloning
Cloning cell-line colonies using cloning rings
Cloning a cell means to derive a (clonal) population of cells from a single cell. In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium. However, in the case of cell cultures from higher organisms, cell cloning is an arduous task as these cells will not readily grow in standard media.
A valuable tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth.
Organism
Asexual reproduction
Organism cloning refers to the procedure of creating a new multicellular organism, genetically identical to another. In essence this form of cloning is an asexual method of reproduction, where fertilization or inter-gamete contact does not take place. Asexual reproduction is a naturally occurring phenomenon in many species, including most plants (see vegetative reproduction) and some insects.
Horticultural
The term clone is used in horticulture to mean all descendants of a single plant, produced by vegetative reproduction or apomixes. Many horticultural plant cultivars are clones, having been derived from a single individual, multiplied by some process other than sexual reproduction. As an example, some European cultivars of grapes represent clones that have been propagated for over two millennia. Other examples are potato and banana. Grafting can be regarded as cloning, since all the shoots and branches coming from the graft are genetically a clone of a single individual, although the root systems may be genetically genuine examples of cloning in the broader biological sense, as they create genetically identical organisms by biological means, but this particular kind of cloning has not come under ethical scrutiny and is generally treated as an entirely different kind of operation.
Many trees, shrubs, vines, ferns and other herbaceous perennials form clonal colonies. Parts of a large clonal colony often become detached from the parent, termed fragmentation, to form separate individuals. Some plants also form seeds asexually, termed apomixes, e.g. dandelion.
Animals
Clonal derivation exists in nature in some animal species and is referred to as parthenogenesis. An example is the "Little Fire Ant" (Wasmannia auropunctata), which is native to Central and South America but has spread throughout many tropical environments.
Reproductive Cloning
Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly the sheep was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth.
Dolly or any other animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. Mitochondria, which are organelles that serve as power sources to the cell, contain their own short segments of DNA, although this is only 0.01% of the total DNA. Acquired mutations in mitochondrial DNA are believed to play an important role in the growing process.
Mutations also occur with every cell division so no two cells in an individual are identical. Thus, nuclear transfer clones from different maternal lineages are not clones in the strictest sense because the mitochondrial genome is not the same as that of the nucleus donor cell from which it was produced. This may have important implications for cross-species nuclear transfer in which nuclear-mitochondrial incompatibilities may lead to death.
Therapeutic Cloning
The technique of cloning specific body organs for medical purposes. For example: If you need a kidney implant, you would get a piece of your DNA and they would grow a new kidney for you. You would not need to take immunodeficiency pills and would not need kidney dialysis anymore. You could live a normal life.
Species cloned
The modern cloning techniques involving nuclear transfer have been successfully performed on several species. Landmark experiments in chronological order:
Tadpole: (1952) many scientists questioned whether cloning had actually occurred and unpublished experiments by other labs were not able to reproduce the reported results.
Carp: (1963) In China, embryologist Tong Dizhou cloned a fish. He published the findings in an obscure Chinese science journal which was never translated into English.[1]
Sheep: (1996) from early embryonic cells by Steen Willadsen. Megan and Morag cloned from differentiated embryonic cells in June 1995 and Dolly the sheep in 1997.
Rhesus Monkey: Tetra (female, January 2000) from embryo splitting
Cattle: Alpha and Beta (males, 2001) and (2005) Brazil[2]
Cat: Copycats "CC" (female, late 2001), Little Nicky, 2004, was the first cat cloned for commercial reasons
Mule: Idaho Gem, a john mule born 2003-05-04, was the first horse-family clone.
Horse: Prometea, a Haflinger female born 2003-05-28, was the first horse clone.
Health aspects
The success rate of cloning has been low: Dolly the sheep was born after 277 eggs were used to create 29 embryos, which only produced three lambs at birth, only one of which lived, Dolly. Seventy calves have been created from 9,000 attempts and one third of them died young; Prometea took 328 attempts, and, more recently, Paris Texas was created after 400 attempts. Notably, although the first clones were frogs, no adult cloned frog has yet been produced from a somatic adult nucleus donor cell.
There were early claims that Dolly the Sheep had accelerated aging. Aging of this type is thought to be due to the shortening of telomeres, regions at the tips of chromosomes which prevent genetic threads from fraying every time a cell divides. Over time telomeres get worn down until cell-division is no longer possible — this is thought to be a cause of aging. However, subsequent studies showed that, if anything, Dolly's telomere were longer than normal. Dolly died in the year of 2003. Ian Wilmut said that Dolly's early death had nothing to do with cloning but with a respiratory infection common to lambs raised like Dolly.
Consistent with Dolly's telomeres being longer, analysis of the telomeres from cloned cows showed that they were also longer. This suggests clones could live longer life spans although many died young after excessive growth. Researchers think that this could eventually be developed to reverse aging in humans, provided that this is based chiefly on the shortening of telomeres. Although some work has been performed on telomeres and aging in nuclear transfer clones, the evidence is at an early stage.
Dolly the Sheep
Cloning is the process of creating an identical copy of something. In Biology, it collectively refers to processes used to create copies of DNA fragments (Molecular Cloning), Cells (Genetic Cloning), or organisms. The term also encompasses situations, whereby organisms reproduce asexually, but in common parlance refers to intentionally created copies of organisms.
Etymology
The term clone is derived from κλων, the Greek word for "twig", referring to the process, whereby a new plant can be created from a twig. In horticulture, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o”.Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively.
Molecular cloning
Molecular cloning refers to the procedure of isolating a defined DNA sequence and obtaining multiple copies of it in vivo. Cloning is frequently employed to amplify DNA fragments containing genes, but it can be used to amplify any DNA sequence such as promoters, non-coding sequences and randomly fragmented DNA. It is utilized in a wide array of biological experiments and practical applications such as large scale protein production. Occasionally, the term cloning is misleadingly used to refer to the identification of the chromosomal location of a gene associated with a particular phenotype of interest, such as in positional cloning. In practice, localization of the gene to a chromosome or genomic region does not necessarily enable one to isolate or amplify the relevant genomic sequence.
In essence, in order to amplify any DNA sequence in a living organism that sequence must be linked to an origin of replication, a sequence element capable of directing the propagation of its self and any linked sequence. In practice, however, a number of other features are desired and a variety of specialized cloning vectors exist that allow protein expression, tagging, single stranded RNA and DNA production and a host of other manipulations.
Cloning of any DNA fragment essentially involves four steps: fragmentation, ligation, transfection, and screening/selection. Although these steps are invariable among cloning procedures a number of alternative routes can be selected, these are summarized as a ‘cloning strategy’.
Initially, the DNA of interest needs to be isolated to provide a relevant DNA segment of suitable size. Subsequently, a ligation procedure is employed whereby the amplified fragment is inserted into a vector. The vector (which is frequently circular) is linearised by means of restriction enzymes, and incubated with the fragment of interest under appropriate conditions with an enzyme called DNA ligase. Following ligation the vector with the insert of interest is transfected into cells. A number of alternative techniques are available, such as chemical sensitivation of cells, electroporation and biolistics. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation. Modern cloning vectors include selectable antibiotic resistance markers, which allow only cells in which the vector has been transfected, too grow. Additionally, the cloning vectors may contain colour selection markers which provide blue/white screening (α-factor complementation) on X-gal medium. Nevertheless, these selection steps do not absolutely guarantee that the DNA insert is present in the cells obtained. Further investigation of the resulting colonies is required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and/or DNA sequencing.
Cellular cloning
Cloning cell-line colonies using cloning rings
Cloning a cell means to derive a (clonal) population of cells from a single cell. In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium. However, in the case of cell cultures from higher organisms, cell cloning is an arduous task as these cells will not readily grow in standard media.
A valuable tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth.
Organism
Asexual reproduction
Organism cloning refers to the procedure of creating a new multicellular organism, genetically identical to another. In essence this form of cloning is an asexual method of reproduction, where fertilization or inter-gamete contact does not take place. Asexual reproduction is a naturally occurring phenomenon in many species, including most plants (see vegetative reproduction) and some insects.
Horticultural
The term clone is used in horticulture to mean all descendants of a single plant, produced by vegetative reproduction or apomixes. Many horticultural plant cultivars are clones, having been derived from a single individual, multiplied by some process other than sexual reproduction. As an example, some European cultivars of grapes represent clones that have been propagated for over two millennia. Other examples are potato and banana. Grafting can be regarded as cloning, since all the shoots and branches coming from the graft are genetically a clone of a single individual, although the root systems may be genetically genuine examples of cloning in the broader biological sense, as they create genetically identical organisms by biological means, but this particular kind of cloning has not come under ethical scrutiny and is generally treated as an entirely different kind of operation.
Many trees, shrubs, vines, ferns and other herbaceous perennials form clonal colonies. Parts of a large clonal colony often become detached from the parent, termed fragmentation, to form separate individuals. Some plants also form seeds asexually, termed apomixes, e.g. dandelion.
Animals
Clonal derivation exists in nature in some animal species and is referred to as parthenogenesis. An example is the "Little Fire Ant" (Wasmannia auropunctata), which is native to Central and South America but has spread throughout many tropical environments.
Reproductive Cloning
Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly the sheep was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth.
Dolly or any other animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. Mitochondria, which are organelles that serve as power sources to the cell, contain their own short segments of DNA, although this is only 0.01% of the total DNA. Acquired mutations in mitochondrial DNA are believed to play an important role in the growing process.
Mutations also occur with every cell division so no two cells in an individual are identical. Thus, nuclear transfer clones from different maternal lineages are not clones in the strictest sense because the mitochondrial genome is not the same as that of the nucleus donor cell from which it was produced. This may have important implications for cross-species nuclear transfer in which nuclear-mitochondrial incompatibilities may lead to death.
Therapeutic Cloning
The technique of cloning specific body organs for medical purposes. For example: If you need a kidney implant, you would get a piece of your DNA and they would grow a new kidney for you. You would not need to take immunodeficiency pills and would not need kidney dialysis anymore. You could live a normal life.
Species cloned
The modern cloning techniques involving nuclear transfer have been successfully performed on several species. Landmark experiments in chronological order:
Tadpole: (1952) many scientists questioned whether cloning had actually occurred and unpublished experiments by other labs were not able to reproduce the reported results.
Carp: (1963) In China, embryologist Tong Dizhou cloned a fish. He published the findings in an obscure Chinese science journal which was never translated into English.[1]
Sheep: (1996) from early embryonic cells by Steen Willadsen. Megan and Morag cloned from differentiated embryonic cells in June 1995 and Dolly the sheep in 1997.
Rhesus Monkey: Tetra (female, January 2000) from embryo splitting
Cattle: Alpha and Beta (males, 2001) and (2005) Brazil[2]
Cat: Copycats "CC" (female, late 2001), Little Nicky, 2004, was the first cat cloned for commercial reasons
Mule: Idaho Gem, a john mule born 2003-05-04, was the first horse-family clone.
Horse: Prometea, a Haflinger female born 2003-05-28, was the first horse clone.
Health aspects
The success rate of cloning has been low: Dolly the sheep was born after 277 eggs were used to create 29 embryos, which only produced three lambs at birth, only one of which lived, Dolly. Seventy calves have been created from 9,000 attempts and one third of them died young; Prometea took 328 attempts, and, more recently, Paris Texas was created after 400 attempts. Notably, although the first clones were frogs, no adult cloned frog has yet been produced from a somatic adult nucleus donor cell.
There were early claims that Dolly the Sheep had accelerated aging. Aging of this type is thought to be due to the shortening of telomeres, regions at the tips of chromosomes which prevent genetic threads from fraying every time a cell divides. Over time telomeres get worn down until cell-division is no longer possible — this is thought to be a cause of aging. However, subsequent studies showed that, if anything, Dolly's telomere were longer than normal. Dolly died in the year of 2003. Ian Wilmut said that Dolly's early death had nothing to do with cloning but with a respiratory infection common to lambs raised like Dolly.
Consistent with Dolly's telomeres being longer, analysis of the telomeres from cloned cows showed that they were also longer. This suggests clones could live longer life spans although many died young after excessive growth. Researchers think that this could eventually be developed to reverse aging in humans, provided that this is based chiefly on the shortening of telomeres. Although some work has been performed on telomeres and aging in nuclear transfer clones, the evidence is at an early stage.
Dolly the Sheep
Pic: Dolly and her first-born lamb, Bonnie
Dolly (1996-07-05 – 2003-02-14), a ewe, was the first mammal to have been successfully cloned from an adult cell. She was cloned at the Roslin Institute in the United Kingdom and lived there until her death when she was 6. On 2003-04-09 her stuffed remains were placed at Edinburgh's Royal Museum, part of the National Museums of Scotland.
Dolly's publicity was inevitable because it demonstrated that the genetic material from a specialized adult cell programmed to express only a distinct subset of its genes, could be reprogrammed to generate an entire new organism. Before this demonstration, there was no proof for the widely spread hypothesis that differentiated animal cells can give rise to new entire new organisms.
Human cloning
Human cloning is the creation of a genetically identical copy of an existing, or previously existing human, by growing cloned tissue from that individual. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.
Human cloning is amongst the most controversial forms of the practice. There have been numerous demands for all progress in the human cloning field to be halted. One of the most ethically questionable problems with human cloning is farming of organs from clones. For example, many believe it is unethical to use a human clone to save the life of another. In this scenario, the cloned human would be euthanized so that the vital organs could be harvested. This process of renewing the body's organs would potentially increase the life expectancy of a human by 50 years.
The cloning described above is reproductive cloning, not to be confused with research cloning in which only parts (such as an organ) are cloned using genetic material from a patient's tissues.
Ethical issues of human cloning
Although the practice of cloning organisms has been widespread for several thousands of years in the form of horticular cloning, the recent technological advancements that have allowed for cloning of animals, and potentially humans have been highly controversial. Many religious groups oppose all forms of cloning, including potentially life saving, cloning of individual organs, on the grounds that life begins at conception. Concerns also exist regarding the protection of the identity of the individual and the right one has to protect their genetic identity.
Cloning extinct and endangered species
Cloning, or more precisely, the reconstruction of functional DNA from extinct species has, for decades, been a dream of some scientists. The possible implications of this were dramatized in the best-selling novel by Michael Crichton and high budget Hollywood thriller Jurassic Park. In real life, one of the most anticipated targets for cloning was once the Woolly Mammoth, but attempts to extract DNA from frozen mammoths have been unsuccessful, though a joint Russo-Japanese team is currently working toward this goal.[5]
In 2000, a cow named Bessie gave birth to a cloned Asian gaur, an endangered species, but the calf died after two days. In 2003, a banteng was successfully cloned, followed by three African wildcats from a thawed frozen embryo. These successes provided hope that similar techniques (using surrogate mothers of another species) might be used to clone extinct species. Anticipating this possibility, tissue samples from the last bucardo (Pyrenean Ibex) were frozen immediately after it died. Researchers are also considering cloning endangered species such as the giant panda, ocelot, and cheetah. The "Frozen Zoo" at the San Diego Zoo now stores frozen tissue from the world's rarest and most endangered species.[6][7]
In 2002, geneticists at the Australian Museum announced that they had replicated DNA of the Thylacine (Tasmanian Tiger), extinct about 65 years previous, using polymerase chain reaction.[8] However, on 2005-02-15 the museum announced that it was stopping the project after tests showed the specimens' DNA had been too badly degraded by the (ethanol) preservative. Most recently, on 2005-05-15, it was announced that the Thylacine project would be revived, with new participation from researchers in New South Wales and Victoria.
One of the continuing obstacles in the attempt to clone extinct species is the need for nearly perfect DNA. Cloning from a single specimen could not create a viable breeding population in sexually reproducing animals. Furthermore, even if males and females were cloned, the question would remain open if they would be viable at all in the absence of parents that could teach or show them natural behavior. Essentially, if cloning an extinct species succeeded — it must be considered that cloning still is an experimental technology that succeeds only by chance — it is far more likely than not that any resulting animals, even if they were healthy, would be little more than curios or museum pieces.
Cloning endangered species is a highly ideological issue. Many conservation biologists and environmentalists vehemently oppose cloning endangered species — not because they think it won't work but because they think it may deter donations to help preserve natural habitat and wild animal populations. The "rule-of-thumb" in animal conservation is that, if it is still feasible to conserve habitat and viable wild populations, breeding in captivity should not be undertaken in isolation.
In a 2006 review, David Ehrenfeld concludes that cloning in animal conservation is an experimental technology that, at its present state, cannot be expected to work except by pure chance and utterly fails a cost-benefit analysis.[9] Furthermore, he says, it is likely to siphon funds from established and working projects and does not address any of the issues underlying animal extinction (such as habitat destruction, hunting or other overexploitation, and an impoverished gene pool). While cloning technologies are well-established and used on a regular basis in plant conservation, care must be taken to ensure genetic diversity. He concludes:
“
Vertebrate cloning poses little risk to the environment, but it can consume scarce conservation resources, and its chances of success in preserving species seem poor. To date, the conservation benefits of transgenic and vertebrate cloning remain entirely theoretical, but many of the risks are known and documented. Conservation biologists should devote their research and energies to the established methods of conservation, none of which require transgenic or vertebrate cloning.
”
Embryo
Somatic cell nuclear transfer can also be used to create a clonal embryo. The most likely scenario for this is to produce embryos for use in research, particularly stem cell research. This process is also called "research cloning" or "therapeutic cloning."
Therapeutic cloning, also called "embryo cloning," is the production of human embryos for use in research. The goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blastocyst. The extraction process destroys the embryo, which raises a variety of ethical concerns. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases.
Scientists believe that cloning may be used to create stem cells genetically compatible with the somatic cell donor. Cloning in stem cell research, called research cloning or therapeutic cloning has not yet been successful: no embryonic stem cell lines have been derived from clonal embryos. The process might provide a way to grow organs in host carriers, so that organs could be produced which would be completely compatible with the original tissue donor. Host carrier growing poses a risk of trans-species diseases if the host is of a different species (e.g., a pig).
In human beings, this is a highly controversial issue for several reasons. It involves creating human embryos in vitro and then destroying them during the process of attempting to obtain embryonic stem cells. But proposals to use cloning techniques in human stem cell research raise a set of concerns beyond the moral status of the embryo. These have led a number of individuals and organizations, who are not opposed in principle to human embryonic stem cell research, to be concerned about or opposed to, human research cloning. One concern is that cloning in human stem cell research will lead to the reproductive cloning of humans. A second concern relates to the appropriate sourcing of the eggs that are needed. Research cloning requires a large number of human eggs, which can only be obtained from women. A third concern is the feasibility of developing stem cell therapies from cloning.
In November 2001, scientists from Advanced Cell Technologies (ACT), a biotechnology company in Massachusetts, announced that they had cloned the first human embryos for the purpose of advancing therapeutic research. To do this, they collected eggs from women's ovaries and then removed the genetic material from these eggs with a needle less than 2/10,000th of an inch wide. A skin cell was inserted inside the enucleated egg to serve as a new nucleus. The egg began to divide after it was stimulated with a chemical called ionomycin. The results were limited in success. Although this process was carried out with eight eggs, only three began dividing, and only one was able to divide into six cells before stopping.
References
^ BLOODLINES. Timeline
^ Wikinews: Endangered cow cloned in Brazil, 2005-05-22
^ Vogel, Gretchen (2000). "In Contrast to Dolly, Cloning Resets Telomere Clock in Cattle". Science 288: 641.
^ Pence, Gregory E. (1998). Who’s Afraid of Human Cloning?. Rowman & Littlefield. paperback ISBN 0-8476-8782-1 and hardcover ISBN 0-8476-8781-3.
^ "Scientists 'to clone mammoth'", BBC News, 2003-08-18.
^ Heidi B. Perlman. "Scientists Close on Extinct Cloning", Associated Press, 2000-10-08.
^ Pence, Gregory E. (2005). Cloning After Dolly: Who's Still Afraid?. Rowman & Littlefield. ISBN 0-7425-3408-1.
^ Holloway, Grant. "Cloning to revive extinct species", CNN.com, 2002-05-28.
^ a b Ehrenfeld, David (2006). "Transgenics and Vertebrate Cloning as Tools for Species Conservation". Conservation Biology 20 (3): 723-732. DOI:10.1111/j.1523-1739.2006.00399.x.
Subscribe to:
Posts (Atom)