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116-621: Hotan (also known by other names ) is a major oasis town in southwestern Xinjiang , an autonomous region in Northwestern China . The city proper of Hotan broke off from the larger Hotan County to become an administrative area in its own right in August 1984. It is the seat of Hotan Prefecture . With a population of 408,900 (2018 census), Hotan is situated in the Tarim Basin some 1,500 kilometres (930 mi) southwest of

232-475: A "central pool of open water surrounded by a ring of water-dependent shrubs and trees…which are in turn encircled by an outlying transition zone to desert plants." Rain showers provide subterranean water to sustain natural oases, such as the Tuat . Substrata of impermeable rock and stone can trap water and retain it in pockets, or on long faulting subsurface ridges or volcanic dikes water can collect and percolate to

348-593: A database) to determine maternal lineage. Most often, the comparison is made with the revised Cambridge Reference Sequence . Vilà et al. have published studies tracing the matrilineal descent of domestic dogs from wolves. The concept of the Mitochondrial Eve is based on the same type of analysis, attempting to discover the origin of humanity by tracking the lineage back in time. Entities subject to uniparental inheritance and with little to no recombination may be expected to be subject to Muller's ratchet ,

464-500: A donor female, and nuclear DNA from the mother and father. In the spindle transfer procedure, the nucleus of an egg is inserted into the cytoplasm of an egg from a donor female which has had its nucleus removed, but still contains the donor female's mtDNA. The composite egg is then fertilized with the male's sperm. The procedure is used when a woman with genetically defective mitochondria wishes to procreate and produce offspring with healthy mitochondria. The first known child to be born as

580-563: A fervently Buddhist city-state boasting some 400 temples in the late 9th/early 10th century—four times the number recorded by Xuanzang around 630. The kingdom was independent but was intermittently under Chinese control during the Han and Tang dynasties. After the Tang dynasty, Khotan formed an alliance with the rulers of Dunhuang. Khotan enjoyed close relations with the Buddhist centre at Dunhuang:

696-435: A finding that has been rejected by other scientists. In sexual reproduction , mitochondria are normally inherited exclusively from the mother; the mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. Also, mitochondria are present solely in the midpiece, which is used for propelling the sperm cells, and sometimes the midpiece, along with the tail, is lost during fertilization. In 1999 it

812-545: A healthy human sperm has been reported to contain on average 5 molecules), degradation of sperm mtDNA in the male genital tract and in the fertilized egg; and, at least in a few organisms, failure of sperm mtDNA to enter the egg. Whatever the mechanism, this single parent ( uniparental inheritance ) pattern of mtDNA inheritance is found in most animals, most plants and also in fungi. In a study published in 2018, human babies were reported to inherit mtDNA from both their fathers and their mothers resulting in mtDNA heteroplasmy ,

928-542: A mutation in mtDNA has been used to help diagnose prostate cancer in patients with negative prostate biopsy . mtDNA alterations can be detected in the bio-fluids of patients with cancer. mtDNA is characterized by the high rate of polymorphisms and mutations. Some of which are increasingly recognized as an important cause of human pathology such as oxidative phosphorylation (OXPHOS) disorders, maternally inherited diabetes and deafness (MIDD), Type 2 diabetes mellitus, Neurodegenerative disease , heart failure and cancer. Though

1044-626: A mutational (contrary to the selective one) explanation for the observation that long-lived species have GC-rich mtDNA: long-lived species become GC-rich simply because of their biased process of mutagenesis. An association between mtDNA mutational spectrum and species-specific life-history traits in mammals opens a possibility to link these factors together discovering new life-history-specific mutagens in different groups of organisms. Deletion breakpoints frequently occur within or near regions showing non-canonical (non-B) conformations, namely hairpins, cruciforms and cloverleaf-like elements. Moreover, there

1160-836: A particular route. For example, the oases of Awjila , Ghadames and Kufra , situated in modern-day Libya , have at various times been vital to both north–south and east–west trade in the Sahara Desert . The location of oases also informed the Darb El Arba'īn trade route from Sudan to Egypt, as well as the caravan route from the Niger River to Tangier , Morocco. The Silk Road "traced its course from water hole to water hole, relying on oasis communities such as Turpan in China and Samarkand in Uzbekistan." According to

1276-782: A pivotal moment in the Turkification and Islamification of the Tarim Basin , the Karakhanid leader Yusuf Qadir Khan conquered Khotan around 1006. Yūsuf Qadr Khān was a brother or cousin of the Muslim ruler of Kashgar and Balasagun , Khotan lost its independence and between 1006 and 1165, became part of the Kara-Khanid Khanate . Later it fell to the Kara-Khitan Khanate , after which it was ruled by

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1392-525: A result of mitochondrial donation was a boy born to a Jordanian couple in Mexico on 6 April 2016. The concept that mtDNA is particularly susceptible to reactive oxygen species generated by the respiratory chain due to its proximity remains controversial. mtDNA does not accumulate any more oxidative base damage than nuclear DNA. It has been reported that at least some types of oxidative DNA damage are repaired more efficiently in mitochondria than they are in

1508-510: A role in the mitochondrial bottleneck, exploiting cell-to-cell variability to ameliorate the inheritance of damaging mutations. According to Justin St. John and colleagues, "At the blastocyst stage, the onset of mtDNA replication is specific to the cells of the trophectoderm . In contrast, the cells of the inner cell mass restrict mtDNA replication until they receive the signals to differentiate to specific cell types." The two strands of

1624-411: A shovel is needed. Wells may or may not be equipped with pumps. Frequently the pumps are broken and useless, and a rope and bucket are then necessary to obtain water. Most of the wells in this region are less than 100 feet deep, but some are deeper, and 100 feet of rope is not too much to provide. As a rule the rope and bucket at a well, if they were ever provided, soon disappear, and one should never trust

1740-435: A species and also for identifying and quantifying the phylogeny (evolutionary relationships; see phylogenetics ) among different species. To do this, biologists determine and then compare the mtDNA sequences from different individuals or species. Data from the comparisons is used to construct a network of relationships among the sequences, which provides an estimate of the relationships among the individuals or species from which

1856-630: A stabilisation or reduction in mutant load between generations. The mechanism underlying the bottleneck is debated, with a recent mathematical and experimental metastudy providing evidence for a combination of the random partitioning of mtDNAs at cell divisions and the random turnover of mtDNA molecules within the cell. Male mitochondrial DNA inheritance has been discovered in Plymouth Rock chickens . Evidence supports rare instances of male mitochondrial inheritance in some mammals as well. Specifically, documented occurrences exist for mice, where

1972-463: Is wahe or ouahe which means a "dwelling place". Oasis in Arabic is wāḥa ( Arabic : واحة ). Oases develop in " hydrologically favored" locations that have attributes such as a high water table , seasonal lakes, or blockaded wadis . Oases are made when sources of freshwater, such as underground rivers or aquifers , irrigate the surface naturally or via man-made wells. The presence of water on

2088-532: Is a linear genome made up of homogeneous DNA molecules (type 5). Great variation in mtDNA gene content and size exists among fungi and plants, although there appears to be a core subset of genes present in all eukaryotes (except for the few that have no mitochondria at all). In Fungi, however, there is no single gene shared among all mitogenomes. Some plant species have enormous mitochondrial genomes, with Silene conica mtDNA containing as many as 11,300,000 base pairs. Surprisingly, even those huge mtDNAs contain

2204-457: Is a small portion of the DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus , and, in plants and algae, the DNA also is found in plastids , such as chloroplasts . Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that human mtDNA has 16,569 base pairs and encodes 13 proteins . As in other vertebrates,

2320-467: Is a well-established marker of oxidative DNA damage. In persons with amyotrophic lateral sclerosis (ALS), the enzymes that normally repair 8-oxoG DNA damages in the mtDNA of spinal motor neurons are impaired. Thus oxidative damage to mtDNA of motor neurons may be a significant factor in the etiology of ALS. Over the past decade, an Israeli research group led by Professor Vadim Fraifeld has shown that strong and significant correlations exist between

2436-406: Is almost identical with that of modern kilims. Hotanese pile carpets are still highly prized and form an important export. Oasis The word oasis came into English from Latin : oasis , from Ancient Greek : ὄασις , óasis , which in turn is a direct borrowing from Demotic Egyptian . The word for oasis in the latter-attested Coptic language (the descendant of Demotic Egyptian)

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2552-615: Is amply stocked with the means of life. Cotton grows here in plenty. It has vineyards, estates and orchards in plenty. The people live by trade and industry; they are not at all warlike". The Qing dynasty of China conquered the Dzungar Khanate during the final stage of the Dzungar–Qing Wars in the late 1750s. By 1760, Hotan became the territory of the Qing dynasty along with the rest of Xinjiang. The town suffered severely during

2668-492: Is data supporting the involvement of helix-distorting intrinsically curved regions and long G-tetrads in eliciting instability events. In addition, higher breakpoint densities were consistently observed within GC-skewed regions and in the close vicinity of the degenerate sequence motif YMMYMNNMMHM. Unlike nuclear DNA, which is inherited from both parents and in which genes are rearranged in the process of recombination , there

2784-480: Is integrated into its desert environment through an often close association with nomadic transhumant livestock farming (very often pastoral and sedentary populations are clearly distinguished). The fertility of the oasis soil is restored by "cyclic organic inputs of animal origin." In summary, an oasis palm grove is a highly anthropized and irrigated area that supports a traditionally intensive and polyculture-based agriculture. Responding to environmental constraints,

2900-436: Is located in the town of Lasqi ( 拉斯奎 ) northwest of the city proper. Passenger train service on this line is limited, with only one train per day, local service 5828/5825, linking the city with Kashgar (8~ hours) and Ürümqi (~34 hours). Regular bus services link Hotan with Kashgar. There is also an express bus to Aksu via the 430 km (270 mi) 'Hotan-Aksu Cross-Desert Highway' which was opened in 2007, travels alongside

3016-514: Is observed in bivalve mollusks. In those species, females have only one type of mtDNA (F), whereas males have F type mtDNA in their somatic cells, but M type of mtDNA (which can be as much as 30% divergent) in germline cells. Paternally inherited mitochondria have additionally been reported in some insects such as fruit flies , honeybees , and periodical cicadas . An IVF technique known as mitochondrial donation or mitochondrial replacement therapy (MRT) results in offspring containing mtDNA from

3132-509: Is one hypothesis for why some genes are retained in mtDNA; colocalisation for redox regulation is another, citing the desirability of localised control over mitochondrial machinery. Recent analysis of a wide range of mtDNA genomes suggests that both these features may dictate mitochondrial gene retention. Across all organisms, there are six main mitochondrial genome types, classified by structure (i.e. circular versus linear), size, presence of introns or plasmid like structures , and whether

3248-434: Is partly due to boundary changes. Hetian Kungang Airport (IATA: HTN ) serves the city. It serves regional flights to Ürümqi . Originally a military use airport, it was expanded significantly in 2002 to accommodate higher passenger volumes. It is located 12 km (7.5 mi) south of the city proper. Hotan is served by China National Highway 315 , which runs along the southern Tarim Basin from Ruoqiang to Kashgar, and

3364-540: Is severely degraded. Autosomal cells only have two copies of nuclear DNA, but can have hundreds of copies of mtDNA due to the multiple mitochondria present in each cell. This means highly degraded evidence that would not be beneficial for STR analysis could be used in mtDNA analysis. mtDNA may be present in bones, teeth, or hair, which could be the only remains left in the case of severe degradation. In contrast to STR analysis, mtDNA sequencing uses Sanger sequencing . The known sequence and questioned sequence are both compared to

3480-429: Is soft, light and graceful tie-dyed silk fabric. It comes various colors, the brighter and rich colors are for small children to young ladies. The gray and dark colors are for elderly women. The oldest piece of kilim which we have any knowledge was obtained by the archaeological explorer Aurel Stein ; a fragment from an ancient settlement near Hotan, which was buried by sand drifts about the fourth century CE. The weave

3596-423: Is the date palm ( Phoenix dactylifera L. ), which forms the upper layer . These palm trees provide shade for smaller understory trees like apricots , dates , figs , olives , and peach trees, which form the middle layer. Market-garden vegetables, some cereals (such as sorghum , barley , millet , and wheat ), and/or mixed animal fodder , are grown in the bottom layer where there is more moisture. The oasis

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3712-485: Is the first multicellular organism known to have this absence of aerobic respiration and live completely free of oxygen dependency. There are three different mitochondrial genome types in plants and fungi. The first type is a circular genome that has introns (type 2) and may range from 19 to 1000 kbp in length. The second genome type is a circular genome (about 20–1000 kbp) that also has a plasmid-like structure (1 kb) (type 3). The final genome type found in plants and fungi

3828-505: Is therefore most likely that the original name of Hotan was Sanskritic in origin, a consequence of ancient Indian settlement in the region. An alternative etymology is proposed by Harold Walter Bailey , an expert in the Khotanese language . He believes the oldest indigenous name to be Hvatana . Hotan was known to 19th-century European explorers as Ilchi . The official Uyghur-to-Latin transliteration, and therefore English spelling, of

3944-452: Is used in an analogous way to determine the patrilineal history.) This is usually accomplished on human mitochondrial DNA by sequencing the hypervariable control regions (HVR1 or HVR2), and sometimes the complete molecule of the mitochondrial DNA, as a genealogical DNA test . HVR1, for example, consists of about 440 base pairs. These 440 base pairs are compared to the same regions of other individuals (either specific people or subjects in

4060-510: Is usually no change in mtDNA from parent to offspring. Although mtDNA also recombines, it does so with copies of itself within the same mitochondrion. Because of this and because the mutation rate of animal mtDNA is higher than that of nuclear DNA, mtDNA is a powerful tool for tracking ancestry through females ( matrilineage ) and has been used in this role to track the ancestry of many species back hundreds of generations. mtDNA testing can be used by forensic scientists in cases where nuclear DNA

4176-521: The POLG2 gene. The replisome machinery is formed by DNA polymerase, TWINKLE and mitochondrial SSB proteins . TWINKLE is a helicase , which unwinds short stretches of dsDNA in the 5' to 3' direction. All these polypeptides are encoded in the nuclear genome. During embryogenesis , replication of mtDNA is strictly down-regulated from the fertilized oocyte through the preimplantation embryo. The resulting reduction in per-cell copy number of mtDNA plays

4292-783: The Dungan Revolt (1862–1877) against the Qing rule and again a few years later when Yaqub Beg of Kashgar made himself master of Kashgaria, ruling the newly founded Turkic state known at the time as Yettishar . However, Xinjiang was reconquered by the Qing dynasty by 1877 and was converted into a province in 1884. Qing imperial authority collapsed in 1912. During the Republican era in China , warlords and local ethnic self-determination movements wrestled over control of Xinjiang. Abdullah Bughra , Nur Ahmad Jan Bughra , and Muhammad Amin Bughra declared themselves Emirs of Khotan during

4408-889: The July 2009 Ürümqi riots , ethnic tensions rose in Xinjiang and in Hotan in particular. As a result, the city has seen occasional bouts of violence. In June 2011, Hotan opened its first passenger-train service to Kashgar , which was established as a special economic zone following the riots. In July of the same year, a bomb and knife attack occurred on the city's central thoroughfare. In June 2011, authorities in Hotan Prefecture sentenced Uyghur Muslim Hebibullah Ibrahim to ten years imprisonment for selling "illegal religious materials". In June 2012, Tianjin Airlines Flight 7554

4524-599: The Kingdom of Khotan . In the 10th century, Khotan began a struggle with the Kara-Khanid Khanate , a Turkic state. The Kara-Khanid ruler, Sultan Satuq Bughra Khan , had converted to Islam : Satuq's son, Musa, began to put pressure on Khotan in the mid-10th century, and sometime before 1006 Yusuf Qadir Khan of Kashgar besieged and took the city. This conquest of Buddhist Khotan by the Muslim Turks—about which there are many colourful legends—marked another watershed in

4640-595: The Kumul Rebellion . Tunganistan was an independent administered region in the southern part of Xinjiang from 1934 to 1937. The territory included the oases of the southern Tarim Basin; the centre of the region was Khotan. Beginning with the Islamic rebellion in 1937 , Hotan and the rest of the province came under the control of warlord Sheng Shicai . Sheng was later ousted by the Kuomintang . Shortly after

4756-475: The Kunlun Mountains to the south in the summer, but it is generally of poorer quality than that found in the rivers. Khotanese textiles were mentioned by Xuanzang , who visited the oasis in 644 CE. In his Biography it is stated: "It produced carpets and fine felt, and the felt-makers also spun coarse and fine silk." Ancient Chinese-Khotanese relations were so close that the oasis emerged as one of

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4872-516: The Mongols . When Marco Polo visited Khotan in the 13th century, he noted that the people were all Muslim. He wrote that: Khotan was "a province eight days’ journey in extent, which is subject to the Great Khan . The inhabitants all worship Mahomet . It has cities and towns in plenty, of which the most splendid, and the capital of the province, bears the same name as that of the province…It

4988-512: The Sampul tapestry , showing the face of Caucasoid man which was made of threads of 24 shades of color. The tapestry had been cut up and fashioned into trousers worn by one of the deceased. An Anthropological study of 56 individuals showed a primarily Caucasoid population. A study in 2010 showed that an Eastern Eurasian lineage common in Siberia dominates the mitochondrial DNA of the mummies from

5104-455: The Tarim mummies were found in the region. At Sampul, east of the city of Hotan, there is an extensive series of cemeteries scattered over an area about 1 kilometre (0.62 mi) wide and 23 km (14 mi) long. The excavated sites range from about 300 BCE to 100 CE. The excavated graves have produced a number of fabrics of felt , wool , silk and cotton and even a fine bit of tapestry,

5220-573: The Western Desert of Egypt ( Kharga , Dakhla , Farafra , Baharyia , and Siwa ) once had "flowing spring and wells" but due to the decline of groundwater heads because of overuse for land reclamation projects those water sources are no more and the oases suffer as a result. Morocco has lost two-thirds of its oasis habitat over the last 100 years due to heat, drought, and water scarcity . The Ferkla Oases in Morocco once drew on water from

5336-563: The White Jade River , to provide the water needed to survive on the southwestern edge of the vast Taklamakan Desert . The White Jade River still provides water and irrigation for the town and oasis. Hotan and its surrounding area were originally known as Godana in ancient Sanskrit cosmological texts. The Chinese transcribed the name as 于窴 , pronounced Gudana in Middle Chinese ( Yutian in modern Standard Chinese );

5452-640: The Xiaohe Cemetery . Their Y chromosome is distributed throughout Eastern Europe, South Asia, Central Asia, and Siberia. There is a relative abundance of information on Hotan readily available for study. The main historical sources are to be found in the Chinese histories (particularly detailed during the Han and early Tang dynasties) when China was interested in control of the Western Regions ,

5568-517: The Xiongnu in 176 BCE, the trade of Khotanese jade into China was controlled by the nomadic Yuezhi . The Chinese still refer to the Yurungkash as the White Jade River , alluding to the white jade recovered from its alluvial deposits . The light-colored jade is called "Mutton fat" jade. Most of the jade is now gone, with only a few kilos of good quality jade found yearly. Some is still mined in

5684-411: The cemetery was demolished and the western part of the land turned into a parking lot. Hotan has a temperate zone, cold desert climate ( Köppen BWk ), with a mean annual total of only 36.5 millimetres (1.44 in) of precipitation falling on 17.3 days of the year. Due to its southerly location in Xinjiang just north of the Kunlun Mountains , during winter it is one of the warmest locations in

5800-413: The eukaryotic nucleus during evolution . The reasons mitochondria have retained some genes are debated. The existence in some species of mitochondrion-derived organelles lacking a genome suggests that complete gene loss is possible, and transferring mitochondrial genes to the nucleus has several advantages. The difficulty of targeting remotely-produced hydrophobic protein products to the mitochondrion

5916-650: The Communists won the civil war in 1949, Hotan was incorporated into the People's Republic of China. In 1983/4, the urban area of Hotan was administratively split from the larger Hotan County , and from then on governed as a county-level city. On July 11, 2006, the townships of Jiya and Yurungqash (Yulongkashi) in Lop County and Tusalla (Tushala) in Hotan County were transferred to Hotan City. Following

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6032-484: The Ferkla, Sat and Tangarfa Rivers but they are now dry but for a few days a year. A 1920 USGS publication about watering holes in the deserts of California and Arizona gave this advice for travelers seeking oases: The usual watering places are springs or wells. Springs are frequently clogged with gravel or rubbish or sometimes even with the bodies of dead animals, and it may be necessary to clean them out. For this work

6148-622: The Islamicisation and Turkicisation of the Tarim Basin , and an end to local autonomy of this southern Tarim city state. Some Khotanese Buddhist works were unearthed. The rulers of Khotan were aware of the menace they faced since they arranged for the Mogao grottoes to paint a growing number of divine figures along with themselves. Halfway in the 10th century Khotan came under attack by the Qarakhanid ruler Musa, and in what proved to be

6264-479: The Khotanese royal family intermarried with Dunhuang élites, visited and patronized Dunhuang's Buddhist temple complex, and donated money to have their portraits painted on the walls of the Mogao grottos. Through the 10th century, Khotanese royal portraits were painted in association with an increasing number of deities in the caves. Besides this, a particular site, Melikawat functioned as a major Buddhist center in

6380-572: The Revised Cambridge Reference Sequence to generate their respective haplotypes. If the known sample sequence and questioned sequence originated from the same matriline, one would expect to see identical sequences and identical differences from the rCRS. Cases arise where there are no known samples to collect and the unknown sequence can be searched in a database such as EMPOP. The Scientific Working Group on DNA Analysis Methods recommends three conclusions for describing

6496-759: The Trans-Taklamakan Desert Highway, which run north to Luntai. An expressway is being built between Hotan and Karakax County (Moyu) as of 2014. Hotan is connected to the rest of China's rail network via the Kashgar–Hotan Railway , which opened to freight traffic in December 2010, and passenger service in June 2011. The railway station was constructed by a company under the Xinjiang Production and Construction Corps , and

6612-837: The United Nations, "Oases are at the very heart of the overall development of peri-Saharan countries due to their geographical location and the fact they are preferred migration routes in times of famine or insecurity in the region." Oases in Oman , on the Arabian Peninsula near the Persian Gulf , vary somewhat from the Saharan form. While still located in an arid or semi-arid zone with a date palm overstory, these oases are usually located below plateaus and "watered either by springs or by aflaj , tunnel systems dug into

6728-764: The accounts of several Chinese pilgrim monks , a few Buddhist histories of Hotan that have survived in Classical Tibetan and a large number of documents in the Iranian Saka language and other languages discovered, for the most part, early this century at various sites in the Tarim Basin and from the hidden library at the Mogao Caves near Dunhuang . In the Hellenistic period, there was an Indo-Greek colony in Khotan. The ancient Kingdom of Khotan

6844-543: The accumulation of deleterious mutations until functionality is lost. Animal populations of mitochondria avoid this through a developmental process known as the mtDNA bottleneck . The bottleneck exploits random processes in the cell to increase the cell-to-cell variability in mutant load as an organism develops: a single egg cell with some proportion of mutant mtDNA thus produces an embryo in which different cells have different mutant loads. Cell-level selection may then act to remove those cells with more mutant mtDNA, leading to

6960-419: The accumulation of mtDNA damage in several organs of rats. For example, dietary restriction prevented age-related accumulation of mtDNA damage in the cortex and decreased it in the lung and testis. Increased mt DNA damage is a feature of several neurodegenerative diseases . The brains of individuals with Alzheimer's disease have elevated levels of oxidative DNA damage in both nuclear DNA and mtDNA, but

7076-505: The chance of finding them there. Open wells are sometimes contaminated in the same way as springs and need to be cleaned out, particularly in little-frequented places where they are unused for months at a time. Mitochondrial DNA Mitochondrial DNA ( mtDNA and mDNA ) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA

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7192-435: The city [ medina ] or village [ ksar ] with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system." The location of oases has been of critical importance for trade and transportation routes in desert areas; caravans must travel via oases so that supplies of water and food can be replenished. Thus, political or military control of an oasis has in many cases meant control of trade on

7308-675: The city only receives 2,587 hours of bright sunshine annually, which is on the low end for Xinjiang; monthly percent possible sunshine ranges from 50% in March to 75% in October. The city includes four subdistricts , three towns , five townships and two other areas: Others: Hotan is largely dominated by the Uyghurs, and as of 2015, 311,050 of the 348,289 residents of the county were Uyghur , 35,897 were Han Chinese and 1,342 were from other ethnic groups. In 1940, Owen Lattimore quoted

7424-456: The coding instructions for some proteins, which may have an effect on organism metabolism and/or fitness. Mutations of mitochondrial DNA can lead to a number of illnesses including exercise intolerance and Kearns–Sayre syndrome (KSS), which causes a person to lose full function of heart, eye, and muscle movements. Some evidence suggests that they might be major contributors to the aging process and age-associated pathologies . Particularly in

7540-718: The context of disease, the proportion of mutant mtDNA molecules in a cell is termed heteroplasmy . The within-cell and between-cell distributions of heteroplasmy dictate the onset and severity of disease and are influenced by complicated stochastic processes within the cell and during development. Mutations in mitochondrial tRNAs can be responsible for severe diseases like the MELAS and MERRF syndromes. Mutations in nuclear genes that encode proteins that mitochondria use can also contribute to mitochondrial diseases. These diseases do not follow mitochondrial inheritance patterns, but instead follow Mendelian inheritance patterns. Recently

7656-403: The differences between a known mtDNA sequence and a questioned mtDNA sequence: exclusion for two or more differences between the sequences, inconclusive if there is one nucleotide difference, or cannot exclude if there are no nucleotide differences between the two sequences. The rapid mutation rate (in animals) makes mtDNA useful for assessing genetic relationships of individuals or groups within

7772-626: The differences in animal species maximum life spans in a multiplicative manner (i.e., species maximum life span = their mtDNA GC% * metabolic rate). To support the scientific community in carrying out comparative analyses between mtDNA features and longevity across animals, a dedicated database was built named MitoAge . De novo mutations arise either due to mistakes during DNA replication or due to unrepaired damage caused in turn by endogenous and exogenous mutagens. It has been long believed that mtDNA can be particularly sensitive to damage caused by reactive oxygen species (ROS), however G>T substitutions,

7888-513: The dull bluish or gray green of the feathery crowns of foliage. It is small wonder that a whole folklore of poetic legends and proverbs has grown up around the date palm in the regions where it flourishes. Many historic oases have struggled with drought and inadequate maintenance. According to a United Nations report on the future of oases in the Sahara and Sahel , "Increasingly   ... oases are subject to various pressures, heavily influenced by

8004-412: The earliest centres of silk manufacture outside China. There are good reasons to believe that the silk-producing industry flourished in Hotan as early as the 5th century. According to one story, a Chinese princess given in marriage to a Khotan prince brought to the oasis the secret of silk-manufacture, "hiding silkworms in her hair as part of her dowry", probably in the first half of the 1st century CE. It

8120-510: The effects of climate change , decreasing groundwater levels and a gradual loss of cultural heritage due to a fading historical memory concerning traditional water management techniques. These natural pressures are compounded by demographic pressures and the introduction of modern water pumping techniques that can disrupt traditional resource management schemes, particularly in the North Saharan oases." For example, five historic oases in

8236-624: The ends of the linear DNA ) with different modes of replication, which have made them interesting objects of research because many of these unicellular organisms with linear mtDNA are known pathogens . Most ( bilaterian ) animals have a circular mitochondrial genome. Medusozoa and calcarea clades however include species with linear mitochondrial chromosomes. With a few exceptions, animals have 37 genes in their mitochondrial DNA: 13 for proteins , 22 for tRNAs , and 2 for rRNAs . Mitochondrial genomes for animals average about 16,000 base pairs in length. The anemone Isarachnanthus nocturnus has

8352-649: The garden resembles a tropical jungle. Very beautiful are these gardens in the spring, when the apricot and peach trees are in blossom here and there among the palms and the figs and vines are putting forth their leaves. In autumn, when the dates are ripening, the color effects, especially when the tops of the palms are lit up by the last rays of the setting sun, are something that once seen can never be forgotten. The great clusters of fruit, displaying every tint from bright yellow, through orange, vermilion, and maroon, to plum purple and chestnut brown, with their brilliant yellow or rich orange ivory-like stalks, contrast superbly with

8468-403: The genetic distances of distantly related species. Statistical models that treat substitution rates among codon positions separately, can thus be used to simultaneously estimate phylogenies that contain both closely and distantly related species Mitochondrial DNA was admitted into evidence for the first time ever in a United States courtroom in 1996 during State of Tennessee v. Paul Ware . In

8584-422: The genetic material is a singular molecule or collection of homogeneous or heterogeneous molecules. In many unicellular organisms (e.g., the ciliate Tetrahymena and the green alga Chlamydomonas reinhardtii ), and in rare cases also in multicellular organisms (e.g. in some species of Cnidaria ), the mtDNA is linear DNA . Most of these linear mtDNAs possess telomerase -independent telomeres (i.e.,

8700-613: The ground or carved into the rock to tap underground aquifers." This rainwater harvesting system "never developed a serious salinity problem." In the drylands of southwestern North America, there is a habitat form called Palm Oasis (alternately Palm Series or Oasis Scrub Woodland) that has the native California fan palm as the overstory species. These Palm Oases can be found in California , Arizona , Baja California , and Sonora . People who live in an oasis must manage land and water use carefully. The most important plant in an oasis

8816-477: The hallmark of the oxidative damage in the nuclear genome, are very rare in mtDNA and do not increase with age. Comparing the mtDNA mutational spectra of hundreds of mammalian species, it has been recently demonstrated that species with extended lifespans have an increased rate of A>G substitutions on single-stranded heavy chain. This discovery led to the hypothesis that A>G is a mitochondria-specific marker of age-associated oxidative damage. This finding provides

8932-431: The human mitochondrial genetic code differs slightly from nuclear DNA. Since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology . It also permits tracing the relationships of populations, and so has become important in anthropology and biogeography . Nuclear and mitochondrial DNA are thought to have separate evolutionary origins, with

9048-421: The human mitochondrial DNA are distinguished as the heavy strand and the light strand. The heavy strand is rich in guanine and encodes 12 subunits of the oxidative phosphorylation system, two ribosomal RNAs (12S and 16S), and 14 transfer RNAs (tRNAs). The light strand encodes one subunit, and 8 tRNAs. So, altogether mtDNA encodes for two rRNAs, 22 tRNAs, and 13 protein subunits , all of which are involved in

9164-524: The idea is controversial, some evidence suggests a link between aging and mitochondrial genome dysfunction. In essence, mutations in mtDNA upset a careful balance of reactive oxygen species (ROS) production and enzymatic ROS scavenging (by enzymes like superoxide dismutase , catalase , glutathione peroxidase and others). However, some mutations that increase ROS production (e.g., by reducing antioxidant defenses) in worms increase, rather than decrease, their longevity. Also, naked mole rats , rodents about

9280-466: The initiation of the transcription of the heavy and light strands are located in the main non-coding region of the mtDNA called the displacement loop, the D-loop . There is evidence that the transcription of the mitochondrial rRNAs is regulated by the heavy-strand promoter 1 (HSP1), and the transcription of the polycistronic transcripts coding for the protein subunits are regulated by HSP2. Measurement of

9396-413: The intermittent Hotan River , and which takes about 5 or 6 hours. This same bus then goes on to Urumchi taking a total of about 21 hours from Hotan. As of 1885, there was about 100,000 acres (662,334 mu ) of cultivated land in Khotan. Chinese historical sources indicate that Hotan was the main source of the nephrite jade used in ancient China . For several hundred years, until they were defeated by

9512-526: The junction of the southern (and most ancient) branch of the Silk Road joining China and the West with one of the main routes from ancient India and Tibet to Central Asia and distant China. It provided a convenient meeting place where not only goods, but technologies, philosophies, and religions were transmitted from one culture to another. Tocharians lived in this region over 2000 years ago. Several of

9628-558: The largest mitochondrial genome of any animal at 80,923 bp. The smallest known mitochondrial genome in animals belongs to the comb jelly Vallicula multiformis , which consist of 9,961 bp. In February 2020, a jellyfish-related parasite – Henneguya salminicola – was discovered that lacks a mitochondrial genome but retains structures deemed mitochondrion-related organelles. Moreover, nuclear DNA genes involved in aerobic respiration and in mitochondrial DNA replication and transcription were either absent or present only as pseudogenes . This

9744-415: The levels of the mtDNA-encoded RNAs in bovine tissues has shown that there are major differences in the expression of the mitochondrial RNAs relative to total tissue RNA. Among the 12 tissues examined the highest level of expression was observed in heart, followed by brain and steroidogenic tissue samples. As demonstrated by the effect of the trophic hormone ACTH on adrenal cortex cells, the expression of

9860-443: The longevity of species. The application of a mitochondrial-specific ROS scavenger, which lead to a significant longevity of the mice studied, suggests that mitochondria may still be well-implicated in ageing. Extensive research is being conducted to further investigate this link and methods to combat ageing. Presently, gene therapy and nutraceutical supplementation are popular areas of ongoing research. Bjelakovic et al. analyzed

9976-424: The male-inherited mitochondria were subsequently rejected. It has also been found in sheep, and in cloned cattle. Rare cases of male mitochondrial inheritance have been documented in humans. Although many of these cases involve cloned embryos or subsequent rejection of the paternal mitochondria, others document in vivo inheritance and persistence under lab conditions. Doubly uniparental inheritance of mtDNA

10092-525: The mitochondrial genes may be strongly regulated by external factors, apparently to enhance the synthesis of mitochondrial proteins necessary for energy production. Interestingly, while the expression of protein-encoding genes was stimulated by ACTH, the levels of the mitochondrial 16S rRNA showed no significant change. In most multicellular organisms , mtDNA is inherited from the mother (maternally inherited). Mechanisms for this include simple dilution (an egg contains on average 200,000 mtDNA molecules, whereas

10208-455: The modern city's name is "Hotan" according to the Register of Chinese Geographic Places . The Hanyu pinyin romanization Hetian has been used on some maps and by some airports. The city's former Chinese name was written with a different character for tian ( simplified Chinese : 阗 ; traditional Chinese : 闐 ; pinyin : tián ). The oasis of Hotan is strategically located at

10324-480: The mtDNA base composition and animal species-specific maximum life spans. As demonstrated in their work, higher mtDNA guanine + cytosine content ( GC% ) strongly associates with longer maximum life spans across animal species. An additional observation is that the mtDNA GC% correlation with the maximum life spans is independent of the well-known correlation between animal species metabolic rate and maximum life spans. The mtDNA GC% and resting metabolic rate explain

10440-448: The mtDNA derived from the circular genomes of bacteria engulfed by the ancestors of modern eukaryotic cells. This theory is called the endosymbiotic theory . In the cells of extant organisms, the vast majority of the proteins in the mitochondria (numbering approximately 1500 different types in mammals ) are coded by nuclear DNA , but the genes for some, if not most, of them are thought to be of bacterial origin, having been transferred to

10556-838: The mtDNA has approximately 10-fold higher levels than nuclear DNA. It has been proposed that aged mitochondria is the critical factor in the origin of neurodegeneration in Alzheimer's disease. Analysis of the brains of AD patients suggested an impaired function of the DNA repair pathway, which would cause reduce the overall quality of mtDNA. In Huntington's disease , mutant huntingtin protein causes mitochondrial dysfunction involving inhibition of mitochondrial electron transport , higher levels of reactive oxygen species and increased oxidative stress . Mutant huntingtin protein promotes oxidative damage to mtDNA, as well as nuclear DNA, that may contribute to Huntington's disease pathology . The DNA oxidation product 8-oxoguanine (8-oxoG)

10672-558: The mtDNAs were taken. mtDNA can be used to estimate the relationship between both closely related and distantly related species. Due to the high mutation rate of mtDNA in animals, the 3rd positions of the codons change relatively rapidly, and thus provide information about the genetic distances among closely related individuals or species. On the other hand, the substitution rate of mt-proteins is very low, thus amino acid changes accumulate slowly (with corresponding slow changes at 1st and 2nd codon positions) and thus they provide information about

10788-472: The nucleus. mtDNA is packaged with proteins which appear to be as protective as proteins of the nuclear chromatin. Moreover, mitochondria evolved a unique mechanism which maintains mtDNA integrity through degradation of excessively damaged genomes followed by replication of intact/repaired mtDNA. This mechanism is not present in the nucleus and is enabled by multiple copies of mtDNA present in mitochondria. The outcome of mutation in mtDNA may be an alteration in

10904-487: The oxidative phosphorylation process. Between most (but not all) protein-coding regions, tRNAs are present (see the human mitochondrial genome map ). During transcription, the tRNAs acquire their characteristic L-shape that gets recognized and cleaved by specific enzymes. With the mitochondrial RNA processing, individual mRNA, rRNA, and tRNA sequences are released from the primary transcript. Folded tRNAs therefore act as secondary structure punctuations. The promoters for

11020-466: The plant and fungal genomes also exist in some protists, as do two unique genome types. One of these unique types is a heterogeneous collection of circular DNA molecules (type 4) while the other is a heterogeneous collection of linear molecules (type 6). Genome types 4 and 6 each range from 1–200 kbp in size. The smallest mitochondrial genome sequenced to date is the 5,967 bp mtDNA of the parasite Plasmodium falciparum . Endosymbiotic gene transfer,

11136-402: The population of Khotan to be estimated as 26,000. In 1998 the urban population was recorded at 154,352, 83% of which were Uyghurs, and 17% were Han Chinese. In 1999, 83.01% of the population was Uyghur and 16.57% of the population was Han Chinese. In the 2000 census, the population was recorded as 186,123. In the 2010 census figure, the figure had risen to 322,300. The increase in population

11252-688: The potential evapotranspiration of the areas was reduced by 30 to 50 percent within the oasis." The keystone date palm trees are "a main income source and staple food for local populations in many countries in which they are cultivated, and have played significant roles in the economy, society, and environment of those countries." Challenges for date palm oasis polycultures include "low rainfall, high temperatures, water resources often high in salt content, and high incidence of pests." The oases consist of almost unbroken forests of date palms, divided up into many gardens that are separated by mud walls and intersected by innumerable irrigation and drainage ditches… In

11368-499: The process by which genes that were coded in the mitochondrial genome are transferred to the cell's main genome, likely explains why more complex organisms such as humans have smaller mitochondrial genomes than simpler organisms such as protists. Mitochondrial DNA is replicated by the DNA polymerase gamma complex which is composed of a 140 kDa catalytic DNA polymerase encoded by the POLG gene and two 55 kDa accessory subunits encoded by

11484-612: The pronunciation eventually morphed into Khotan . In the 7th century, the Chinese Buddhist monk and scholar Xuanzang attempted to remedy this lexical change. Xuanzang, who was well-versed in Sanskrit, proposed that the traditional name was in fact Kustana ( गौस्तन ) and asserted it meant "breast of the earth". However, this was likely borrowed from the Tibetan name for the region, Gosthana , which means "land of cows". It

11600-553: The region, with average high temperatures remaining above freezing throughout the year. The monthly 24-hour average temperature ranges from −3.9 °C (25.0 °F) in January to 25.8 °C (78.4 °F) in July, and the annual mean is 13.03 °C (55.5 °F). The diurnal temperature variation is not large for a desert, averaging 11.8 °C (21.2 °F) annually. Although no month averages less than half of possible sunshine,

11716-528: The regional capital, Ürümqi . It lies just north of the Kunlun Mountains , which are crossed by the Sanju , Hindutash and Ilchi passes. The town, located southeast of Yarkant County and populated almost exclusively by Uyghurs , is a minor agricultural center. An important station on the southern branch of the historic Silk Road , Hotan has always depended on two strong rivers, the Karakash River and

11832-409: The results of 78 studies between 1977 and 2012, involving a total of 296,707 participants, and concluded that antioxidant supplements do not reduce all-cause mortality nor extend lifespan, while some of them, such as beta carotene, vitamin E, and higher doses of vitamin A, may actually increase mortality. In a recent study, it was shown that dietary restriction can reverse ageing alterations by affecting

11948-442: The same number and kinds of genes as related plants with much smaller mtDNAs. The genome of the mitochondrion of the cucumber ( Cucumis sativus ) consists of three circular chromosomes (lengths 1556, 84 and 45 kilobases), which are entirely or largely autonomous with regard to their replication . Protists contain the most diverse mitochondrial genomes, with five different types found in this kingdom. Type 2, type 3 and type 5 of

12064-399: The shade of the palms are grown many other kinds of fruit trees—oranges, olives, figs, apricots, peaches, pomegranates, and jujubes—interlaced with large grape vines that often hang in festoons from the palm trunks. Beneath the trees are small plots of garden vegetables, barley, and alfalfa. Neither date palms nor other trees are planted with any regularity, and the growth is often so dense that

12180-500: The size of mice , live about eight times longer than mice despite having reduced, compared to mice, antioxidant defenses and increased oxidative damage to biomolecules. Once, there was thought to be a positive feedback loop at work (a 'Vicious Cycle'); as mitochondrial DNA accumulates genetic damage caused by free radicals, the mitochondria lose function and leak free radicals into the cytosol . A decrease in mitochondrial function reduces overall metabolic efficiency. However, this concept

12296-593: The surface or underground is necessary and the local or regional management of this essential resource is strategic, but not sufficient to create such areas: continuous human work and know-how (a technical and social culture) are essential to maintain such ecosystems. Some of the possible human contributions to maintaining an oasis include digging and maintaining wells, digging and maintaining canals, and continuously removing opportunistic plants that threaten to gorge themselves on water and fertility needed to maintain human and animal food supplies. Stereotypically, an oasis has

12412-474: The surface. Any incidence of water is then used by migrating birds , which also pass seeds with their droppings which will grow at the water's edge forming an oasis. It can also be used to plant crops. Oases in the Middle East and North Africa cover about 1,000,000 hectares (10,000 km ), however, they support the livelihood of about 10 million inhabitants. The stark ratio of oasis to desert land in

12528-426: The three strata create what is called the " oasis effect ". The three layers and all their interaction points create a variety of combinations of "horizontal wind speed, relative air temperature and relative air humidity." The plantings—through a virtuous cycle of wind reduction, increased shade and evapotranspiration —create a microclimate favorable to crops; "measurements taken in different oases have showed that

12644-648: The water into individual plots, soaking the soil." Oases often have human histories that are measured in millennia. Archeological digs at Ein Gedi in the Dead Sea Valley have found evidence of settlement dating to 6,000 BC. Al-Ahsa on the Arabian Peninsula shows evidence of human residence dating to the Neolithic . Anthropologically , the oasis is "an area of sedentary life, which associates

12760-400: The world means that the oasis ecosystem is "relatively minute, rare and precious." There are 90 “major oases” within the Sahara Desert. Some of their fertility may derive from irrigation systems called foggaras , khettaras , lkhttarts , or a variety of other regional names . In some oases systems, there is "a geometrical system of raised channels that release controlled amounts of

12876-528: Was a historical Uyghur graveyard that also included a religious shrine. According to a 2019 interview by the Uyghur Human Rights Project , the cemetery entombed four commanders of Sultan Satuq Bughra Khan, who conquered the city around 960 CE and spread Islam. Due to space limitations after over a thousand years of burials, multiple bodies had to reuse the same grave, and additionals layers were dug underneath old ones. Between 2018 and 2019,

12992-410: Was conclusively disproved when it was demonstrated that mice, which were genetically altered to accumulate mtDNA mutations at accelerated rate do age prematurely, but their tissues do not produce more ROS as predicted by the 'Vicious Cycle' hypothesis. Supporting a link between longevity and mitochondrial DNA, some studies have found correlations between biochemical properties of the mitochondrial DNA and

13108-454: Was from Khotan that the eggs of silkworms were smuggled to Iran , reaching Justinian I 's Constantinople in 551. Silk production is still a major industry employing more than a thousand workers and producing some 150 million metres of silk annually. Silk weaving by Uyghur women is a thriving cottage industry , some of it produced using traditional methods. Atlas is the fabric used for traditional Uyghur clothing worn by Uyghur women. It

13224-776: Was hijacked en route from Hotan to Ürümqi. In a report from the Uyghur American Association , in June 2012, notice was said to be given that police planned to undertake a search of every residence in Gujanbagh (Gujiangbage), Hotan. Hotan is the last municipality in Xinjiang with a majority Ugyhur presence in the core of the city. The UAA viewed this as an attempt to systematically intimidate the Uyghur population in Hotan. The Sultanim Cemetery ( 37°07′02″N 79°56′04″E  /  37.11722°N 79.93444°E  / 37.11722; 79.93444 ) in central Hotan

13340-566: Was one of the earliest Buddhist states in the world and a cultural bridge across which Buddhist culture and learning were transmitted from India to China. Its capital was located to the west of the modern city of Hotan. The inhabitants of the Kingdom of Khotan, like those of early Kashgar and Yarkant , spoke Saka , one of the Eastern Iranian languages . Khotan's indigenous dynasty (all of whose royal names are Indian in origin) governed

13456-460: Was reported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin to select them for later destruction inside the embryo . Some in vitro fertilization techniques, particularly injecting a sperm into an oocyte , may interfere with this. The fact that mitochondrial DNA is mostly maternally inherited enables genealogical researchers to trace maternal lineage far back in time. ( Y-chromosomal DNA , paternally inherited,

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