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Saturday, March 21, 2020

Acetylcholine

From Wikipedia, the free encyclopedia

Acetylcholine
Acetylcholine.svg
Clinical data
Other namesACh
Physiological data
Source tissuesmotor neurons, parasympathetic nervous system, brain
Target tissuesskeletal muscles, brain, many other organs
Receptorsnicotinic, muscarinic
Agonistsnicotine, muscarine, cholinesterase inhibitors
Antagoniststubocurarine, atropine
Precursorcholine, acetyl-CoA
Biosynthesischoline acetyltransferase
Metabolismacetylcholinesterase
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
KEGG
E numberE1001(i) (additional chemicals) Edit this at Wikidata
CompTox Dashboard (EPA)
ECHA InfoCard100.000.118 Edit this at Wikidata
Chemical and physical data
FormulaC7H16NO2
Molar mass146.210 g·mol−1

Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (and humans) as a neurotransmitter—a chemical message released by nerve cells to send signals to other cells, such as neurons, muscle cells and gland cells. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Parts in the body that use or are affected by acetylcholine are referred to as cholinergic. Substances that interfere with acetylcholine activity are called anticholinergics.

Acetylcholine is the neurotransmitter used at the neuromuscular junction—in other words, it is the chemical that motor neurons of the nervous system release in order to activate muscles. This property means that drugs that affect cholinergic systems can have very dangerous effects ranging from paralysis to convulsions. Acetylcholine is also a neurotransmitter in the autonomic nervous system, both as an internal transmitter for the sympathetic nervous system and as the final product released by the parasympathetic nervous system. Acetylcholine is the primary neurotransmitter of the parasympathetic nervous systems.

In the brain, acetylcholine functions as a neurotransmitter and as a neuromodulator. The brain contains a number of cholinergic areas, each with distinct functions; such as playing an important role in arousal, attention, memory and motivation.

Acetylcholine (ACh), has also been traced in cells of non-neural origins and microbes. Recently, enzymes related to its synthesis, degradation and cellular uptake have been traced back to early origins of unicellular eukaryotes. The protist pathogen Acanthamoeba spp. has shown the presence of ACh, which provides growth and proliferative signals via a membrane located M1-muscarinic receptor homolog.

Partly because of its muscle-activating function, but also because of its functions in the autonomic nervous system and brain, many important drugs exert their effects by altering cholinergic transmission. Numerous venoms and toxins produced by plants, animals, and bacteria, as well as chemical nerve agents such as Sarin, cause harm by inactivating or hyperactivating muscles via their influences on the neuromuscular junction. Drugs that act on muscarinic acetylcholine receptors, such as atropine, can be poisonous in large quantities, but in smaller doses they are commonly used to treat certain heart conditions and eye problems. Scopolamine, which acts mainly on muscarinic receptors in the brain, can cause delirium and amnesia. The addictive qualities of nicotine are derived from its effects on nicotinic acetylcholine receptors in the brain.

Chemistry

Acetylcholine is a choline molecule that has been acetylated at the oxygen atom. Because of the presence of a highly polar, charged ammonium group, acetylcholine does not penetrate lipid membranes. Because of this, when the drug is introduced externally, it remains in the extracellular space and does not pass through the blood–brain barrier. A synonym of this drug is miochol.

Biochemistry

Acetylcholine is synthesized in certain neurons by the enzyme choline acetyltransferase from the compounds choline and acetyl-CoA. Cholinergic neurons are capable of producing ACh. An example of a central cholinergic area is the nucleus basalis of Meynert in the basal forebrain. The enzyme acetylcholinesterase converts acetylcholine into the inactive metabolites choline and acetate. This enzyme is abundant in the synaptic cleft, and its role in rapidly clearing free acetylcholine from the synapse is essential for proper muscle function. Certain neurotoxins work by inhibiting acetylcholinesterase, thus leading to excess acetylcholine at the neuromuscular junction, causing paralysis of the muscles needed for breathing and stopping the beating of the heart.

Functions

Acetylcholine pathway.

functions in both the central nervous system (CNS) and the peripheral nervous system (PNS). In the CNS, cholinergic projections from the basal forebrain to the cerebral cortex and hippocampus support the cognitive functions of those target areas. In the PNS, acetylcholine activates muscles and is a major neurotransmitter in the autonomic nervous system.

Cellular effects

Acetylcholine processing in a synapse. After release acetylcholine is broken down by the enzyme acetylcholinesterase.

Like many other biologically active substances, acetylcholine exerts its effects by binding to and activating receptors located on the surface of cells. There are two main classes of acetylcholine receptor, nicotinic and muscarinic. They are named for chemicals that can selectively activate each type of receptor without activating the other: muscarine is a compound found in the mushroom Amanita muscaria; nicotine is found in tobacco. 

Nicotinic acetylcholine receptors are ligand-gated ion channels permeable to sodium, potassium, and calcium ions. In other words, they are ion channels embedded in cell membranes, capable of switching from a closed to an open state when acetylcholine binds to them; in the open state they allow ions to pass through. Nicotinic receptors come in two main types, known as muscle-type and neuronal-type. The muscle-type can be selectively blocked by curare, the neuronal-type by hexamethonium. The main location of muscle-type receptors is on muscle cells, as described in more detail below. Neuronal-type receptors are located in autonomic ganglia (both sympathetic and parasympathetic), and in the central nervous system.

Muscarinic acetylcholine receptors have a more complex mechanism, and affect target cells over a longer time frame. In mammals, five subtypes of muscarinic receptors have been identified, labeled M1 through M5. All of them function as G protein-coupled receptors, meaning that they exert their effects via a second messenger system. The M1, M3, and M5 subtypes are Gq-coupled; they increase intracellular levels of IP3 and calcium by activating phospholipase C. Their effect on target cells is usually excitatory. The M2 and M4 subtypes are Gi/Go-coupled; they decrease intracellular levels of cAMP by inhibiting adenylate cyclase. Their effect on target cells is usually inhibitory. Muscarinic acetylcholine receptors are found in both the central nervous system and the peripheral nervous system of the heart, lungs, upper gastrointestinal tract, and sweat glands.

Neuromuscular junction

Muscles contract when they receive signals from motor neurons. The neuromuscular junction is the site of the signal exchange. The steps of this process in vertebrates occur as follows: (1) The action potential reaches the axon terminal. (2) Calcium ions flow into the axon terminal. (3) Acetylcholine is released into the synaptic cleft. (4) Acetylcholine binds to postsynaptic receptors. (5) This binding causes ion channels to open and allows sodium ions to flow into the muscle cell. (6) The flow of sodium ions across the membrane into the muscle cell generates an action potential which induces muscle contraction. Labels: A: Motor neuron axon B: Axon terminal C: Synaptic cleft D: Muscle cell E: Part of a Myofibril

Acetylcholine is the substance the nervous system uses to activate skeletal muscles, a kind of striated muscle. These are the muscles used for all types of voluntary movement, in contrast to smooth muscle tissue, which is involved in a range of involuntary activities such as movement of food through the gastrointestinal tract and constriction of blood vessels. Skeletal muscles are directly controlled by motor neurons located in the spinal cord or, in a few cases, the brainstem. These motor neurons send their axons through motor nerves, from which they emerge to connect to muscle fibers at a special type of synapse called the neuromuscular junction.

When a motor neuron generates an action potential, it travels rapidly along the nerve until it reaches the neuromuscular junction, where it initiates an electrochemical process that causes acetylcholine to be released into the space between the presynaptic terminal and the muscle fiber. The acetylcholine molecules then bind to nicotinic ion-channel receptors on the muscle cell membrane, causing the ion channels to open. Sodium ions then flow into the muscle cell, initiating a sequence of steps that finally produce muscle contraction.

Factors that decrease release of acetylcholine (and thereby affecting P-type calcium channels):

Autonomic nervous system

Components and connections of the parasympathetic nervous system.
 
The autonomic nervous system controls a wide range of involuntary and unconscious body functions. Its main branches are the sympathetic nervous system and parasympathetic nervous system. Broadly speaking, the function of the sympathetic nervous system is to mobilize the body for action; the phrase often invoked to describe it is fight-or-flight. The function of the parasympathetic nervous system is to put the body in a state conducive to rest, regeneration, digestion, and reproduction; the phrase often invoked to describe it is "rest and digest" or "feed and breed". Both of these aforementioned systems use acetylcholine, but in different ways.

At a schematic level, the sympathetic and parasympathetic nervous systems are both organized in essentially the same way: preganglionic neurons in the central nervous system send projections to neurons located in autonomic ganglia, which send output projections to virtually every tissue of the body. In both branches the internal connections, the projections from the central nervous system to the autonomic ganglia, use acetylcholine as a neurotransmitter to innervate (or excite) ganglia neurons. In the parasympathetic nervous system the output connections, the projections from ganglion neurons to tissues that don't belong to the nervous system, also release acetylcholine but act on muscarinic receptors. In the sympathetic nervous system the output connections mainly release noradrenaline, although acetylcholine is released at a few points, such as the sudomotor innervation of the sweat glands.

Direct vascular effects

Acetylcholine in the serum exerts a direct effect on vascular tone by binding to muscarinic receptors present on vascular endothelium. These cells respond by increasing production of nitric oxide, which signals the surrounding smooth muscle to relax, leading to vasodilation.

Central nervous system

Micrograph of the nucleus basalis (of Meynert), which produces acetylcholine in the CNS. LFB-HE stain.
 
In the central nervous system, ACh has a variety of effects on plasticity, arousal and reward. ACh has an important role in the enhancement of alertness when we wake up, in sustaining attention  and in learning and memory.

Damage to the cholinergic (acetylcholine-producing) system in the brain has been shown to be associated with the memory deficits associated with Alzheimer's disease. ACh has also been shown to promote REM sleep.

In the brainstem acetylcholine originates from the Pedunculopontine nucleus and laterodorsal tegmental nucleus collectively known as the mesopontine tegmentum area or pontomesencephalotegmental complex. In the basal forebrain, it originates from the basal nucleus of Meynert and medial septal nucleus:
In addition, ACh acts as an important internal transmitter in the striatum, which is part of the basal ganglia. It is released by cholinergic interneurons. In humans, non-human primates and rodents, these interneurons respond to salient environmental stimuli with responses that are temporally aligned with the responses of dopaminergic neurons of the substantia nigra.

Memory

Acetylcholine has been implicated in learning and memory in several ways. The anticholinergic drug, scopolamine, impairs acquisition of new information in humans and animals. In animals, disruption of the supply of acetylcholine to the neocortex impairs the learning of simple discrimination tasks, comparable to the acquisition of factual information and disruption of the supply of acetylcholine to the hippocampus and adjacent cortical areas produces forgetting comparable to anterograde amnesia in humans.

Diseases and disorders

Myasthenia gravis

The disease myasthenia gravis, characterized by muscle weakness and fatigue, occurs when the body inappropriately produces antibodies against acetylcholine nicotinic receptors, and thus inhibits proper acetylcholine signal transmission. Over time, the motor end plate is destroyed. Drugs that competitively inhibit acetylcholinesterase (e.g., neostigmine, physostigmine, or primarily pyridostigmine) are effective in treating this disorder. They allow endogenously released acetylcholine more time to interact with its respective receptor before being inactivated by acetylcholinesterase in the synaptic cleft (the space between nerve and muscle).

Pharmacology

Blocking, hindering or mimicking the action of acetylcholine has many uses in medicine. Drugs acting on the acetylcholine system are either agonists to the receptors, stimulating the system, or antagonists, inhibiting it. Acetylcholine receptor agonists and antagonists can either have an effect directly on the receptors or exert their effects indirectly, e.g., by affecting the enzyme acetylcholinesterase, which degrades the receptor ligand. Agonists increase the level of receptor activation, antagonists reduce it.

Acetylcholine itself does not have therapeutic value as a drug for intravenous administration because of its multi-faceted action (non-selective) and rapid inactivation by cholinesterase. However, it is used in the form of eye drops to cause constriction of the pupil during cataract surgery, which facilitates quick post-operational recovery.

Nicotinic receptors

Nicotine binds to and activates nicotinic acetylcholine receptors, mimicking the effect of acetylcholine at these receptors. When ACh interacts with a nicotinic ACh receptor, it opens a Na+ channel and Na+ ions flow into the membrane. This causes a depolarization, and results in an excitatory post-synaptic potential. Thus, ACh is excitatory on skeletal muscle; the electrical response is fast and short-lived. Curares are arrow poisons, which act at nicotinic receptors and have been used to develop clinically useful therapies.

Muscarinic receptors

Atropine is a non-selective competitive antagonist with Acetylcholine at muscarinic receptors.

Cholinesterase inhibitors

Many ACh receptor agonists work indirectly by inhibiting the enzyme acetylcholinesterase. The resulting accumulation of acetylcholine causes continuous stimulation of the muscles, glands, and central nervous system, which can result in fatal convulsions if the dose is high.

They are examples of enzyme inhibitors, and increase the action of acetylcholine by delaying its degradation; some have been used as nerve agents (Sarin and VX nerve gas) or pesticides (organophosphates and the carbamates). Many toxins and venoms produced by plants and animals also contain cholinesterase inhibitors. In clinical use, they are administered in low doses to reverse the action of muscle relaxants, to treat myasthenia gravis, and to treat symptoms of Alzheimer's disease (rivastigmine, which increases cholinergic activity in the brain).

Synthesis inhibitors

Organic mercurial compounds, such as methylmercury, have a high affinity for sulfhydryl groups, which causes dysfunction of the enzyme choline acetyltransferase. This inhibition may lead to acetylcholine deficiency, and can have consequences on motor function.

Release inhibitors

Botulinum toxin (Botox) acts by suppressing the release of acetylcholine, whereas the venom from a black widow spider (alpha-latrotoxin) has the reverse effect. ACh inhibition causes paralysis. When bitten by a black widow spider, one experiences the wastage of ACh supplies and the muscles begin to contract. If and when the supply is depleted, paralysis occurs.

Comparative biology and evolution

Acetylcholine is used by organisms in all domains of life for a variety of purposes. It is believed that choline, a precursor to acetylcholine, was used by single celled organisms billions of years ago for synthesizing cell membrane phospholipids. Following the evolution of choline transporters, the abundance of intracellular choline paved the way for choline to become incorporated into other synthetic pathways, including acetylcholine production. Acetylcholine is used by bacteria, fungi, and a variety of other animals. Many of the uses of acetylcholine rely on its action on ion channels via GPCRs like membrane proteins. 

The two major types of acetylcholine receptors, muscarinic and nicotinic receptors, have convergently evolved to be responsive to acetylcholine. This means that rather than having evolved from a common homolog, these receptors evolved from separate receptor families. It is estimated that the nicotinic receptor family dates back longer than 2.5 billion years. Likewise, muscarinic receptors are thought to have diverged from other GPCRs at least 0.5 billion years ago. Both of these receptor groups have evolved numerous subtypes with unique ligand affinities and signaling mechanisms. The diversity of the receptor types enables acetylcholine to create varying responses depending on which receptor types are activated, and allow for acetylcholine to dynamically regulate physiological processes.

History

In 1867, Adolf von Baeyer resolved the structures of choline and acetylcholine and synthetized them both, referring to the latter as "acetylneurin" in the study. Choline is a precursor for acetylcholine. This is why Frederick Walker Mott and William Dobinson Halliburton noted in 1899 that choline injections decreased the blood pressure of animals. Acetylcholine was noted to be biologically active in 1906, when Reid Hunt (1870–1948) and René de M. Taveau found that it decreased blood pressure in exceptionally tiny doses.

In 1914, Arthur J. Ewins was to first to extract acetylcholine from nature. He identified it as the blood pressure decreasing contaminant from some Claviceps purpurea ergot extracts, by the request of Henry Hallett Dale. Later in 1914, Dale outlined the effects of acetylcholine at various types of peripheral synapses and also noted that it lowered the blood pressure of cats via subcutaneous injections even at doses of one nanogram.

The concept neurotransmitters was unknown before 1921, when Otto Loewi noted that the vagus nerve secreted a substance that stimulated the heart muscle whilst working as a professor in the University of Graz. He named it vagusstoff ("vagus substance"), noted it to be a structural analog of choline and suspected it to be acetylcholine. In 1926, Loewi and E. Navratil deduced that the compound is probably acetylcholine, as vagusstoff and synthetic acetylcholine lost their activity in a similar manner when in contact with tissue lysates that contained acetylcholine-degrading enzymes (now known to be cholinesterases). This conclusion was accepted widely. Later studies confirmed the function of acetylcholine as a neurotransmitter.

In 1936, H. H. Dale and O. Loewi shared the Nobel Prize in Physiology or Medicine for their studies relating to acetylcholine and nerve impulses.

Convicts in Australia

From Wikipedia, the free encyclopedia
 
Convicts in New Holland, 1793, by Juan Ravenet.

Between 1788 and 1868, about 162,000 convicts were transported from Britain and Ireland to various penal colonies in Australia.

The British Government began transporting convicts overseas to American colonies in the early 17th century. When transporting convicts ended with the start of the American Revolution, an alternative site was needed to relieve further overcrowding of British prisons and hulks. Earlier in 1770, James Cook charted and claimed possession of the east coast of Australia for Britain. Seeking to pre-empt the French colonial empire from expanding into the region, Britain chose Australia as the site of a penal colony, and in 1787, the First Fleet of eleven convict ships set sail for Botany Bay, arriving on 20 January 1788 to found Sydney, New South Wales, the first European settlement on the continent. Other penal colonies were later established in Van Diemen's Land (Tasmania) in 1803 and Queensland in 1824, while Western Australia, founded in 1829 as a free colony, received convicts from 1850. South Australia and Victoria, established in 1836 and 1850 respectively, remained free colonies. Penal transportation to Australia peaked in the 1830s and dropped off significantly the following decade as protests against the convict system intensified throughout the colonies. In 1868, almost two decades after transportation to the eastern colonies had ceased, the last convict ship arrived in Western Australia.

The majority of convicts were transported for petty crimes. More serious crimes, such as rape and murder, became transportable offences in the 1830s, but since they were also punishable by death, comparatively few convicts were transported for such crimes. Approximately 1 in 7 convicts were women, while political prisoners, another minority group, comprise many of the best-known convicts. Once emancipated, most ex-convicts stayed in Australia and joined the free settlers, with some rising to prominent positions in Australian society. However, convictism carried a social stigma, and for some later Australians, the nation's convict origins instilled a sense of shame and cultural cringe. Attitudes became more accepting in the 20th century and it is now considered by many Australians to be a cause for celebration to have a convict in one's lineage. Around 20% of modern Australians, in addition to 2 million Britons, are descended from transported convicts. The convict era has inspired famous novels, films, and other cultural works, and the extent to which it has shaped Australia's national character has been studied by many writers and historians.

Reasons for transportation


According to Robert Hughes in The Fatal Shore, the population of England and Wales, which had remained steady at 6 million from 1700 to 1740, began rising considerably after 1740. By the time of the American Revolution, London was overcrowded, filled with the unemployed, and flooded with cheap gin. Poverty, social injustice, child labour, harsh and dirty living conditions and long working hours were prevalent in 19th-century Britain. Dickens's novels perhaps best illustrate this; even some government officials were horrified by what they saw. Only in 1833 and 1844 were the first general laws against child labour (the Factory Acts) passed in the United Kingdom. Crime had become a major problem and, in 1784, a French observer noted that "from sunset to dawn the environs of London became the patrimony of brigands for twenty miles around."

Prison hulks in the River Thames

Each parish had a watchman, but British cities did not have police forces in the modern sense. Jeremy Bentham avidly promoted the idea of a circular prison, but the penitentiary was seen by many government officials as a peculiar American concept. Virtually all malefactors were caught by informers or denounced to the local court by their victims. Pursuant to the so-called "Bloody Code", by the 1770s there were 222 crimes in Britain which carried the death penalty, almost all of which were crimes against property. These included such offences as the stealing of goods worth over 5 shillings, the cutting down of a tree, the theft of an animal, even the theft of a rabbit from a warren.

The Industrial Revolution led to an increase in petty crime because of the economic displacement of much of the population, building pressure on the government to find an alternative to confinement in overcrowded gaols. The situation was so dire that hulks left over from the Seven Years' War were used as makeshift floating prisons. Four out of five prisoners were in jail for theft. The Bloody Code was gradually rescinded in the 1800s because judges and juries considered its punishments too harsh. Since lawmakers still wanted punishments to deter potential criminals, they increasingly applied transportation as a more humane alternative to execution. Transportation had been employed as a punishment for both major and petty crimes since the seventeenth century. Around 60,000 convicts were transported to the British colonies in North America in the seventeenth and eighteenth centuries. Transportation to the Americas ceased following Britain's defeat in the American Revolutionary War. The number of convicts transported to North America is not verified although it has been estimated to be 50,000 by John Dunmore Lang and 120,000 by Thomas Keneally. The British American colony of Maryland received a larger felon quota than any other province.

Penal settlements

New South Wales

The First Fleet arrives in Botany Bay, 21 January 1788, by William Bradley (1802).
 
Convicts at Botany Bay from Captain Watkin Tench's Narrative of the Expedition to Botany Bay. First published in 1789.
 
The Costumes of the Australasians: watercolour by Edward Charles Close shows the co-existence of convicts, their military gaolers, and free settlers.

Alternatives to the American colonies were investigated and the newly discovered and mapped East Coast of New Holland was proposed. The details provided by James Cook during his expedition to the South Pacific in 1770 made it the most suitable.

On 18 August 1786 the decision was made to send a colonisation party of convicts, military, and civilian personnel to Botany Bay under the command of Admiral Arthur Phillip who was to be the Governor of the new colony. There were 775 convicts on board six transport ships. They were accompanied by officials, members of the crew, marines, the families thereof and their own children who together totaled 645. In all, eleven ships were sent in what became known as the First Fleet. Other than the convict transports, there were two naval escorts and three storeships. The fleet assembled in Portsmouth and set sail on 13 May 1787.

The fleet arrived at Botany Bay on 20 January 1788. It soon became clear that it would not be suitable for the establishment of a colony due to "the openness of this bay, and the dampness of the soil, by which the people would probably be rendered unhealthy" and Philip decided to examine Port Jackson, a bay mentioned by Captain Cook, about three leagues to the north. On 22 January a small expedition led by Phillips sailed to Port Jackson, arriving in the early afternoon:
Here all regret arising from the former disappointments was at once obliterated; and Governor Phillip had the satisfaction to find one of the finest harbours in the world, in which a thousand sail of the line might ride in perfect security. The different coves of this harbour were examined with all possible expedition, and the preference was given to one which had the finest spring of water, and in which ships can anchor so close to the shore, that at a very small expence quays may be constructed at which the largest vessels may unload. This cove is about half a mile in length, and a quarter of a mile across at the entrance. In honour of Lord Sydney, the Governor distinguished it by the name of Sydney Cove.
There they established the first permanent European colony on the Australian continent, New South Wales, on 26 January. The area has since developed into the city of Sydney. This date is still celebrated as Australia Day.

There was initially a high mortality rate amongst the members of the first fleet due mainly to shortages of food. The ships carried only enough food to provide for the settlers until they could establish agriculture in the region. Unfortunately, there were an insufficient number of skilled farmers and domesticated livestock to do this, and the colony waited for the arrival of the Second Fleet. The "Memorandoms" by James Martin (convict) provide a contemporary account of the events as seen by a convict on the first fleet. The second fleet was an unprecedented disaster that provided little in the way of help and upon its delivery in June 1790 of still more sick and dying convicts, which actually worsened the situation in Port Jackson.

Lieutenant-General Sir Richard Bourke was the ninth Governor of the Colony of New South Wales between 1831 and 1837. Appalled by the excessive punishments doled out to convicts, Bourke passed 'The Magistrates Act', which limited the sentence a magistrate could pass to fifty lashes (previously there was no such limit). Bourke's administration was controversial, and furious magistrates and employers petitioned the crown against this interference with their legal rights, fearing that a reduction in punishments would cease to provide enough deterrence to the convicts.

Bourke, however, was not dissuaded from his reforms and continued to create controversy within the colony by combating the inhumane treatment handed out to convicts, including limiting the number of convicts each employer was allowed to seventy, as well as granting rights to freed convicts, such as allowing the acquisition of property and service on juries. It has been argued that the suspension of convict transportation to New South Wales in 1840 can be attributed to the actions of Bourke and other men like Australian-born lawyer William Charles Wentworth. It took another 10 years, but transportation to the colony of New South Wales was finally officially abolished on 1 October 1850.

If a convict was well behaved, the convict could be given a ticket of leave, granting some freedom. At the end of the convict's sentence, seven years in most cases, the convict was issued with a Certificate of Freedom. He was then free to become a settler or to return to England. Convicts who misbehaved, however, were often sent to a place of secondary punishment like Port Arthur, Tasmania or Norfolk Island, where they would suffer additional punishment and solitary confinement.

Norfolk Island

Norfolk Island military barracks.

Within a month of the arrival of the First Fleet at Sydney Cove, a group of convicts and free settlers were sent to take control of Norfolk Island, a small island 1,412 kilometres (877 mi) east of the coast of New South Wales. More convicts were sent, and many of them proved to be unruly; early 1789 saw a failed attempt to overthrow Lieutenant Philip Gidley King, the island's commandant. This was followed by the wreck of HMS Sirius on one of the island's reefs while attempting to land stores.

Tasmania

Penitentiary at the Port Arthur convict settlement, Tasmania

In 1803, a British expedition was sent from Sydney to Tasmania (then known as Van Diemen's Land) to establish a new penal colony there. The small party, led by Lt. John Bowen, established a settlement at Risdon Cove, on the eastern side of the Derwent River. Originally sent to Port Philip, but abandoned within weeks, another expedition led by Lieutenant-Colonel David Collins arrived soon after. Collins considered the Risdon Cove site inadequate, and in 1804 he established an alternative settlement on the western side of the river at Sullivan's Cove, Tasmania. This later became known as Hobart, and the original settlement at Risdon Cove was deserted. Collins became the first Lieutenant-Governor of Van Diemen's Land.

When the convict station on Norfolk Island was abandoned in 1807-1808, the remaining convicts and free settlers were transported to Hobart and allocated land for re-settlement. However, as the existing small population was already experiencing difficulties producing enough food, the sudden doubling of the population was almost catastrophic.

Starting in 1816, more free settlers began arriving from Great Britain. On 3 December 1825 Tasmania was declared a colony separate from New South Wales, with a separate administration.

Macquarie Harbour Penal Station, depicted by convict artist William Buelow Gould, 1833

The Macquarie Harbour penal colony on the West Coast of Tasmania was established in 1820 to exploit the valuable timber Huon Pine growing there for furniture making and shipbuilding. Macquarie Harbour had the added advantage of being almost impossible to escape from, most attempts ending with the convicts either drowning, dying of starvation in the bush, or (on at least two occasions) turning cannibal. Convicts sent to this settlement had usually re-offended during their sentence of transportation, and were treated very harshly, labouring in cold and wet weather, and subjected to severe corporal punishment for minor infractions.

In 1830, the Port Arthur penal settlement was established to replace Macquarie Harbour, as it was easier to maintain regular communications by sea. Although known in popular history as a particularly harsh prison, in reality its management was far more humane than Macquarie Harbour or the outlying stations of New South Wales. Experimentation with the so-called model prison system took place in Port Arthur. Solitary confinement was the preferred method of punishment.

Many changes were made to the manner in which convicts were handled in the general population, largely responsive to British public opinion on the harshness of their treatment. Until the late 1830s most convicts were either retained by Government for public works or assigned to private individuals as a form of indentured labour. From the early 1840s the Probation System was employed, where convicts spent an initial period, usually two years, in public works gangs on stations outside of the main settlements, then were freed to work for wages within a set district.

Transportation to Tasmania ended in 1853 (see section below on Cessation of Transportation).

Victoria

William Buckley's transportation and escape to live with the Wathaurong in 1803, as depicted by 19th-century Aboriginal artist Tommy McRae.

In 1803 two ships arrived in Port Phillip, which Lt. John Murray in the Lady Nelson had discovered and named the previous year. The Calcutta under the command of Lieutenant-Colonel Collins transported 300 convicts, accompanied by the supply ship Ocean. Collins had previously been Judge Advocate with the First Fleet in 1788. He chose Sullivan Bay near the present-day Sorrento, Victoria for the first settlement - some 90 km south of present-day Melbourne. About two months later the settlement was abandoned due to poor soil and water shortages and Collins moved the convicts to Hobart. Several convicts had escaped into the bush and were left behind to unknown fates with the local aboriginal people. One such convict, the subsequently celebrated William Buckley, lived in the western side of Port Phillip for the next 32 years before approaching the new settlers and assisting as an interpreter for the indigenous peoples.

A second settlement was established at Westernport Bay, on the site of present-day Corinella, in November 1826. It comprised an initial 20 soldiers and 22 convicts, with another 12 convicts arriving subsequently. This settlement was abandoned in February 1828, and all convicts returned to Sydney.

The Port Phillip District was officially sanctioned in 1837 following the landing of the Henty brothers in Portland Bay in 1834, and John Batman settled on the site of Melbourne.

Between 1844 and 1849 about 1,750 convicts arrived there from England. They were referred to either as "Exiles" or the "Pentonvillians" because most of them came from Pentonville Probationary Prison. Unlike earlier convicts who were required to work for the government or on hire from penal depots, the Exiles were free to work for pay, but could not leave the district to which they were assigned. The Port Phillip District was still part of New South Wales at this stage. Victoria separated from New South Wales and became an independent colony in 1851.

Queensland

In 1823 John Oxley sailed north from Sydney to inspect Port Curtis and Moreton Bay as possible sites for a penal colony. At Moreton Bay he found the Brisbane River, which Cook had guessed would exist, and explored the lower part of it. In September 1824, he returned with soldiers and established a temporary settlement at Redcliffe. On 2 December 1824, the settlement was transferred to where the Central Business District (CBD) of Brisbane now stands. The settlement was at first called Edenglassie. In 1839 transportation of convicts to Moreton Bay ceased and the Brisbane penal settlement was closed. In 1842 free settlement was permitted and people began to colonize the area voluntarily. On 6 June 1859 Queensland became a colony separate from New South Wales.

Western Australia

Fremantle Prison gatehouse. The prison was built using convict labour in the 1850s.

Although a convict-supported settlement was established in Western Australia from 1826 to 1831, direct transportation of convicts did not begin until 1850. It continued until 1868. During that period, 9,668 convicts were transported on 43 convict ships. The first convicts to arrive were transported to New South Wales, and sent by that colony to King George Sound (Albany) in 1826 to help establish a settlement there. At that time the western third of Australia was unclaimed land known as New Holland. Fears that France would lay claim to the land prompted the Governor of New South Wales, Ralph Darling, to send Major Edmund Lockyer, with troops and 23 convicts, to establish a settlement at King George Sound. Lockyer's party arrived on Christmas Day, 1826. A convict presence was maintained at the settlement for over four years. On 7 March 1831 control of the settlement was transferred to the Swan River Colony, and the troops and convicts were withdrawn.

In April 1848, Charles Fitzgerald, Governor of Western Australia, petitioned Britain to send convicts to his state because of labor shortages. Britain rejected sending fixed term convicts, but offered to send first offenders in the final years of their terms.

Most convicts in Western Australia spent very little time in prison. Those who were stationed at Fremantle were housed in the Convict Establishment, the colony's convict prison, and misbehaviour was punished by stints there. The majority, however, were stationed in other parts of the colony. Although there was no convict assignment in Western Australia, there was a great demand for public infrastructure throughout the colony, so that many convicts were stationed in remote areas. Initially, most offenders were set to work creating infrastructure for the convict system, including the construction of the Convict Establishment itself.

In 1852 a Convict Depot was built at Albany, but closed 3 years later. When shipping increased the Depot was re-opened. Most of the convicts had their Ticket-of-Leave and were hired to work by the free settlers. Convicts also manned the pilot boat, rebuilt York Street and Stirling Terrace; and the track from Albany to Perth was made into a good road. An Albany newspaper noted their commendable behaviour and wrote, "There were instances in which our free settlers might take an example".

Western Australia's convict era came to an end with the cessation of penal transportation by Britain. In May 1865, the colony was advised of the change in British policy, and told that Britain would send one convict ship in each of the years 1865, 1866 and 1867, after which transportation would cease. In accordance with this, the last convict ship to Western Australia, the Hougoumont, left Britain in 1867 and arrived in Western Australia on 10 January 1868.

Women

Between 1788 and 1852, about 24,000 transportees were women, one in seven. 80% of women had been convicted of theft, usually petty. For protection, many quickly attached themselves to male officers or convicts. Although they were routinely referred to as courtesans, no women were transported for prostitution, as it was not a transportable offence.

Political prisoners

Painting of the 1804 Castle Hill convict rebellion
 
Fenian convicts escape from Fremantle in the 1876 Catalpa rescue.

Political prisoners made up a small proportion of convicts. They arrived in waves corresponding to political unrest in Britain and Ireland. They included the First Scottish Martyrs in 1794; British Naval Mutineers (from the Nore Mutiny) in 1797 and 1801; Irish rebels in 1798, 1803, 1848 and 1868; Scots Rebels (1820); Yorkshire Rebels (1820 and 1822); leaders of the Merthyr Tydfil rising of 1831; the Tolpuddle Martyrs (1834); Swing Rioters and Luddites (1828–1833); American and French-Canadian prisoners from the Upper Canada rebellion and Lower Canada Rebellion (1839), and Chartists (1842).

Cessation of transportation

With increasing numbers of free settlers entering New South Wales and Van Diemen's Land (Tasmania) by the mid-1830s, opposition to the transportation of felons into the colonies grew. The most influential spokesmen were newspaper proprietors who were also members of the Independent Congregation Church such as John Fairfax in Sydney and the Reverend John West in Launceston, who argued against convicts both as competition to honest free labourers and as the source of crime and vice within the colony. Bishop Bernard Ullathorne, a Catholic prelate who had been in Australia since 1832 returned for a visit to England in 1835. While there he was called upon by the government to give evidence before a Parliamentary Commission on the evils of transportation, and at their request wrote and submitted a tract on the subject. His views in conjunction with others in the end prevailed. The anti-transportation movement was seldom concerned with the inhumanity of the system, but rather the hated stain it was believed to inflict on the free (non-emancipist) middle classes.

Transportation to New South Wales ended in 1840, by which time some 150,000 convicts had been sent to the colonies. The sending of convicts to Brisbane in its Moreton Bay district had ceased the previous year, and administration of Norfolk Island was later transferred to Van Diemen's Land.

Opposition to transportation was not unanimous; wealthy landowner, Benjamin Boyd, for reasons of economic self-interest, wanted to use transported convicts from Van Diemen's Land as a source of free or low-cost labour in New South Wales, particularly as shepherds.

The continuation of transportation to Van Diemen's Land saw the rise of a well-coordinated anti-transportation movement, especially following a severe economic depression in the early 1840s. Transportation was temporarily suspended in 1846 but soon revived with overcrowding of British gaols and clamour for the availability of transportation as a deterrent. By the late 1840s most convicts being sent to Van Diemen's Land (plus those to Victoria) were designated as "exiles" and were free to work for pay while under sentence. In 1850 the Australasian Anti-Transportation League was formed to lobby for the permanent cessation of transportation, its aims being furthered by the commencement of the Australian gold rushes the following year. The last convict ship to be sent from England, the St. Vincent, arrived in 1853, and on 10 August Jubilee festivals in Hobart and Launceston celebrated 50 years of European settlement with the official end of transportation.

Transportation continued in small numbers to Western Australia. The last convict ship, the Hougoumont, left Britain in 1867 and arrived in Western Australia on 10 January 1868. In all, about 164,000 convicts were transported to the Australian colonies between 1788 and 1868 on board 806 ships. Convicts were made up of English and Welsh (70%), Irish (24%), Scottish (5%) and the remaining 1% from the British outposts in India and Canada, Maoris from New Zealand, Chinese from Hong Kong and slaves from the Caribbean.

Only South Australia and the Northern Territory had never accepted convicts directly from England but they still accepted ex-convicts from the other states. Many convicts were allowed to travel as far as New Zealand to make a new life after being given limited freedom. At this time the Australian population was approximately 1 million and the colonies could now sustain themselves without the need for convict labour.

Legacy

Hyde Park Barracks, designed by convict Francis Greenway and constructed by convicts in the 1810s, is one of eleven World Heritage-listed Australian Convict Sites.

In 2010, UNESCO inscribed 11 Australian Convict Sites on its World Heritage List. The listing recognises the sites as "the best surviving examples of large-scale convict transportation and the colonial expansion of European powers through the presence and labour of convicts."

Cultural depictions

Marcus Clarke (c. 1866), author of For the Term of His Natural Life, Australia's most famous convict novel
 
Convict Alexander Pearce has inspired three feature films (drawings by convict Thomas Bock, 1824).

Convict George Barrington is (perhaps apocryphally) recorded as having written the prologue for the first theatrical play performed by convicts in Australia, one year after the First Fleet's arrival. It is known as "Our Country's Good", based on the now-famous closing stanza:
From distant climes, o'er wide-spread seas, we come,
Though not with much éclat or beat of drum,
True patriots all: for, be it understood:
We left our country for our country's good.
The poems of Frank the Poet are among the few surviving literary works done by a convict while still incarcerated. His best-known work is "A Convict's Tour of Hell". A version of the convict ballad "Moreton Bay", detailing the brutal punishments meted out by commandment Patrick Logan and his death at the hands of Aborigines, is also attributed to Frank. Other convict ballads include "Jim Jones at Botany Bay". The ballad "Botany Bay", which describes the sadness felt by convicts forced to leave their loved ones in England, was written at least 40 years after the end of transportation.

Perhaps the most famous convict in all of fiction is Abel Magwitch, a main character of Charles Dickens' 1861 novel Great Expectations. The most famous convict novel is Marcus Clarke's For the Term of His Natural Life (1874), followed by John Boyle O'Reilly's Moondyne (1879). The Broad Arrow by Caroline Woolmer Leakey was one of the first novels to depict the convict experience, and one of the only to feature a female convict as its protagonist (Marcus Clarke drew on Leakey's book in writing For the Term of His Natural Life). Thomas Keneally explores the convict era in his novels Bring Larks and Heroes (1967) and The Playmaker (1987). Convicts feature heavily in Patrick White's take on the Eliza Fraser story, the 1976 novel A Fringe of Leaves. Convictism is canvassed in Bryce Courtenay's "Australian trilogy": The Potato Factory (1995), Tommo & Hawk (1997) and Solomon's Song (1999). The title character of Peter Carey's 1997 novel Jack Maggs is a reworking of Dickens' Magwitch character. Many modern works of Tasmanian Gothic focus on the state's convict past, including Gould's Book of Fish (2001) by Richard Flanagan, a fictionalised account of convict artist William Buelow Gould's imprisonment at Macquarie Harbour. Kate Grenville based the novel The Secret River (2005) on the life of her convict ancestor Solomon Wiseman.

Along with bushrangers and other stock characters of colonial life, convicts were a popular subject during Australia's silent film era. The first convict film was a 1908 adaptation of Marcus Clarke's For the Term of His Natural Life, shot on location at Port Arthur with an unheard-of budget of £7000. This was followed by two more films inspired by Clarke's novel: The Life of Rufus Dawes (1911), which draws on Alfred Dampier's stage production of His Natural Life, and the landmark For the Term of His Natural Life (1927), one of the most expensive silent films ever made. W. J. Lincoln directed many convict melodramas including It Is Never Too Late to Mend (1911), an adaptation of Charles Reade's 1856 novel about cruelties of the convict system; Moodyne (1913), based on John Boyle O'Reilly's novel; and Transported (1913). Other early titles include Sentenced for Life, The Mark of the Lash, One Hundred Years Ago, The Lady Outlaw and The Assigned Servant, all released in 1911. Few convict films were made after 1930; even the Australian New Wave of the 1970s, with its emphasis on Australia's colonial past, largely avoided the convict era in favour of nostalgic period pieces set in the bush around the time of Federation. One exception is Journey Among Women (1977), a feminist imagining of what life was like for convict women. Alexander Pearce, the infamous Tasmanian convict and cannibal, is the inspiration for The Last Confession of Alexander Pearce (2008), Dying Breed (2008) and Van Diemen's Land (2009). The British film Comrades (1986) deals with the transportation of the Tolpuddle Martyrs to Australia.

Notable convicts transported to Australia

  • Esther AbrahamsBritish Jew, who was one of the Jewish convicts (about 1,000 in all) and common law wife of a leader of the Rum Rebellion.
  • George Barrington - pickpocket, superintendant of convicts and high constable of Parramatta
  • Samuel Barsby – one of the first two coopers in Australia and the first convict to be flogged
  • Joseph Backler – transported for passing forged cheques, became a colonial painter
  • William Bannon – transported from New Zealand to Van Diemen's Land for army desertion/theft. Escaped Port Arthur through the 'dog line' at EagleHawk Neck.
  • Billy Blue – black man from Jamaica, New York, established a ferry service
  • James Blackburn – Famous for contribution to Australian architecture and civil engineering
  • William Bland – naval surgeon transported for killing a man in a duel; he prospered and was involved in philanthropy, and had a seat in the legislative assembly.
  • Mary Bryant – famous escapee
  • William Buckley – famously escaped and lived with Aboriginal people for many years
  • John Cadman – had been a publican, as a convict became Superintendent of Boats in Sydney; Cadmans Cottage is a cottage granted to him.
  • Martin Cash – Famous escapee and bushranger
  • William Chopin – a convict whose work in prison hospitals in Western Australia grounded him in chemistry; on receiving a ticket of leave he was appointed chemist at the Colonial Hospital, but preferred to open his own chemist shop. He was later convicted as an abortionist.
  • Daniel Connor – sentenced to seven years transportation for sheep stealing, became successful merchant, by the 1890s one of the largest landowners in central Perth.
  • Daniel Cooper – successful merchant.
  • William Cuffay (convict and tailor) – Black London Chartist leader who became an important workers' rights leader in Hobart.
  • John Davies – co-founded The Mercury newspaper.
  • Margaret DawsonFirst Fleeter, "founding mother"
  • John Eyre – painter and engraver
  • William Field – notable Tasmanian businessman and landowner
  • Francis Greenway – famous Australian architect
  • William Henry Groom – successful auctioneer and politician, served in the inaugural Australian Parliament.
  • Michael Howe - bushranger, subject of the first work of general literature published in Australia
  • Laurence Hynes Halloran – founded Sydney Grammar School.
  • William Hutchinson – public servant and pastoralist.
  • John Irving – doctor transported on First Fleet, was the first convict to receive an absolute pardon.
  • Mark Jeffrey – wrote famous autobiography
  • Jørgen Jørgensen – eccentric Danish adventurer influenced by revolutionary ideas who declared himself ruler of Iceland, later became a spy in Britain.
  • Henry Kable – First Fleet convict, arrived with wife and son (Susannah Holmes, also a convict, and Henry) filed 1st lawsuit in Australia, became wealthy businessman
  • Lawrence Kavenagh – notorious bushranger
  • John "Red" Kelly – Irish convict and father of bushranger Ned Kelly
  • Solomon Levey – wealthy merchant, endowed Sydney Grammar School.
  • Simeon Lord – pioneer merchant and magistrate in Australia
  • Nathaniel Lucas – one of the first convicts on Norfolk Island, where he became Master carpenter, later farmed successfully, built windmills, and was Superintendent of carpenters in Sydney.
  • John MitchelIrish nationalist
  • Francis "Frank the Poet" McNamara – composer of various oral convict ballads, including The Convict's Tour to Hell
  • John Mortlock – former marine
  • Thomas Muir – convicted of sedition for advocating parliamentary reform; escaped from N.S.W and after many vicissitudes made his way to revolutionary France.
  • Isaac Nichols – entrepreneur, first Postmaster
  • Kevin Izod O'Doherty – Medical student, Young Irelander who was transported for treason.
  • Robert Palin – once in Australia, committed further crimes, and managed to be executed for a non-capital offence
  • Alexander Pearce – cannibal escapee
  • Joseph Potaskie – first Pole to come to Australia.
  • William Smith O'Brien – famous Irish revolutionary; sent to Van Diemen's Land in 1849 after leading a rebellion in Tipperary
  • John Boyle O'Reilly – Famous escapee, poet and writer; author of Moondyne
  • William Redfern – one of the few surgeon convicts
  • Mary Reibey – businesswoman and shipowner
  • James Ruse – successful farmer
  • Henry Savery – Australia's first novelist; author of Quintus Servinton
  • Robert Sidaway – opened Australia's first theatre
  • Ikey Solomon – professional thief; inspiration for the character Fagin in Charles Dickens' novel Oliver Twist
  • James Squire – English Romanichal (Romany) – First Fleet convict and Australia's first brewer and cultivator of hops.
  • Joseph Sullivan – sentenced to fourteen years transportation for stealing, then killed for murdering his master and the other convicts in the area.
  • William Sykes – historically interesting because he left a brief diary and a bundle of letters.
  • John Tawell – served his sentence, became a prosperous chemist, returned to England after 15 years, and after some time murdered a mistress, for which he was hanged.
  • Samuel Terry – wealthy merchant and philanthropist.
  • James Hardy Vaux – author of Australia's first full length autobiography and dictionary.
  • Mary Wade – Youngest female convict transported to Australia (13 years of age) who had 21 children and at the time of her death had over 300 living descendants.
  • William Westwood – bushranger and leader of the 1846 Cooking Pot Uprising
  • Joseph Wildexplorer
  • Solomon Wiseman – merchant and operated ferry on Hawkesbury River hence town name Wisemans Ferry.
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