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Rhynchosciara Americana
''Rhynchosciara americana'' is a species of fly. It has a life cycle of approximately 70 days, and the sibling larvae show a synchronized development. The larvae can reach one inch in length, and the adult fly is about 0.8 inch (20 mm). The larvae groups are usually originated from the same female posture and spin a communal cocoon where the metamorphosis will occur. The fly is scientifically notable for the physiology of its polytene chromosomes and developmentally regulated amplified puffs, first observed by Crodowaldo Pavan. Its ecology is poorly understood, but it is assumed to be a fungus gnat. Until recently, scientists had no success in the laboratory breeding of this fly. Entomologist Christian Rudolph Wilhelm Wiedemann first described and classified this species in his work ''Diptera Exotica'' (1821). He had analyzed Brazilian specimens probably sent to him by colleagues or enthusiasts. European entomologists had difficulty visiting Brazil to collect samples f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian Rudolph Wilhelm Wiedemann
Christian Rudolph Wilhelm Wiedemann (7 December 1770 in Brunswick – 31 December 1840 in Kiel) was a German physician, historian, naturalist and entomologist. He is best known for his studies of world Diptera, but he also studied Hymenoptera and Coleoptera, although far less expertly. Biography Wiedemann’s father, Conrad Eberhard Wiedemann (1722–1804) was an art dealer and his mother, Dorothea Frederike (née Raspe) (1741–1804) was the daughter of an accountant in the Royal Mining Service and also interested in the arts. After his education in Brunswick, he matriculated in 1790 to the Faculty of Medicine at the University of Jena where he was a contemporary of the poet Friedrich von Hardenberg. While attending university, Wiedemann, was one of the many pupils of Johann Friedrich Blumenbach, and travelled to Saxony and Bohemia. He obtained his doctoral degree in 1792 with a thesis entitled ''Dissertatio inauguralis sistens vitia gennus humanum debilitantia''. He then w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polytene Chromosome
Polytene chromosomes are large chromosomes which have thousands of DNA strands. They provide a high level of function in certain tissues such as salivary glands of insects. Polytene chromosomes were first reported by E.G.Balbiani in 1881. Polytene chromosomes are found in dipteran flies: the best understood are those of ''Drosophila'', ''Chironomus'' and '' Rhynchosciara''. They are present in another group of arthropods of the class Collembola, a protozoan group Ciliophora, mammalian trophoblasts and antipodal, and suspensor cells in plants. In insects, they are commonly found in the salivary glands when the cells are not dividing. They are produced when repeated rounds of DNA replication without cell division forms a giant chromosome. Thus polytene chromosomes form when multiple rounds of replication produce many sister chromatids ''which stay fused together''. Polytene chromosomes, at interphase, are seen to have distinct thick and thin banding patterns. These patterns w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crodowaldo Pavan
Crodowaldo Pavan (; December 1, 1919 – April 3, 2009) was a Brazilian biologist and geneticist, and a scientific leader in Brazil. Early life Pavan was born to a family of second-generation immigrants from Italy in 1919, in the city of Campinas, São Paulo state, Brazil. His great-grandfather was an expert in textile paints and a militant anarchist, who was frequently persecuted and imprisoned in Italy as well as in Brazil for his political activism. As a boy, influenced by his father's porcelain manufacturing plant at Mogi das Cruzes, he wished to follow a career in engineering, but changed radically when he had the opportunity in high school to attend a lecture by noted French physician and professor André Dreyfus and a screening of the film "The Story of Louis Pasteur", starring Oscar-winning actor Paul Muni in the title role. Studies Following Dreyfus' advice, in 1938 he enrolled in a course of natural history at the University of São Paulo, continuing to work in bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophilidae
The Drosophilidae are a diverse, cosmopolitan family of flies, which includes species called fruit flies, although they are more accurately referred to as vinegar or pomace flies. Another distantly related family of flies, Tephritidae, are true fruit flies because they are frugivorous, and include apple maggot flies and many pests. The best known species of the Drosophilidae is ''Drosophila melanogaster'', within the genus ''Drosophila'', also called the "fruit fly." ''Drosophila melanogaster'' is used extensively for studies concerning genetics, development, physiology, ecology and behaviour. Many fundamental biological mechanisms were discovered first in ''D. melanogaster.'' The fruit fly is mostly composed of post-mitotic cells, has a very short lifespan, and shows gradual aging. As in other species, temperature influences the life history of the animal. Several genes have been identified that can be manipulated to extend the lifespan of these insects. Additionally, ''Drosophi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
São Paulo (state)
São Paulo () is one of the Federative units of Brazil, 26 states of the Brazil, Federative Republic of Brazil and is named after Paul of Tarsus, Saint Paul of Tarsus. A major industrial complex, the state has 21.9% of the Brazilian population and is responsible for 33.9% of Brazil's GDP. São Paulo also has the List of Brazilian federative units by Human Development Index, second-highest Human Development Index (HDI) and GDP per capita, the List of Brazilian states by infant mortality, fourth-lowest infant mortality rate, the List of Brazilian states by life expectancy, third-highest life expectancy, and the List of Brazilian states by literacy rate, third-lowest rate of illiteracy among the federative units of Brazil. São Paulo alone is wealthier than Argentina, Uruguay, Paraguay, and Bolivia combined. São Paulo is also the world's twenty-eighth-most populous Administrative division, sub-national entity and the most populous sub-national entity in the Americas. With more than 4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chironomus
''Chironomus'' is a genus of nonbiting midges in the subfamily Chironominae of the bloodworm family, Chironomidae, containing several cryptic species that can only be distinguished by experts based on the characteristics of their giant chromosomes. Description Adult ''Chironomus'' are midges with the pronotum widest in the middle and bearing a notch, the head usually bearing a pair of small tubercles above the antennal bases, the antennal flagellum of males having 11 segments, and the male genitalia has inferior volsella large and larger than superior volsella. They range from 5 to 13 mm in length. Larvae are red and usually have tubes on the side or bottom of the eighth abdominal segment. These features are not unique to ''Chironomus'', also being found in some related genera. Adult males can be distinguished from females by their feather-like antennae. Behaviour When at rest, adults often raise their front legs and vibrate them. This is the source of the genus name, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thymidine
Thymidine (symbol dT or dThd), also known as deoxythymidine, deoxyribosylthymine, or thymine deoxyriboside, is a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine (A) in double-stranded DNA. In cell biology it is used to synchronize the cells in G1/early S phase. The prefix deoxy- is often left out since there are no precursors of thymine nucleotides involved in RNA synthesis. Before the boom in thymidine use caused by the need for thymidine in the production of the antiretroviral drug azidothymidine (AZT), much of the world's thymidine production came from herring sperm. Thymidine occurs almost exclusively in DNA but it also occurs in the T-loop of tRNA. Structure and properties In its composition, deoxythymidine is a nucleoside composed of deoxyribose (a pentose sugar) joined to the pyrimidine base thymine. Deoxythymidine can be phosphorylated with one, two or three phosphoric acid groups, creating dTMP (deoxythymidine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Replication
In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritance. This is essential for cell division during growth and repair of damaged tissues, while it also ensures that each of the new cells receives its own copy of the DNA. The cell possesses the distinctive property of division, which makes replication of DNA essential. DNA is made up of a double helix of two complementary strands. The double helix describes the appearance of a double-stranded DNA which is thus composed of two linear strands that run opposite to each other and twist together to form. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as semiconservative replication. As a result of semi-conservative rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect. ''D. melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. ''D. melanogaster'' is a common pest in homes, restaurants, and othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sciaridae
The Sciaridae are a family of flies, commonly known as dark-winged fungus gnats. Commonly found in moist environments, they are known to be a pest of mushroom farms and are commonly found in household plant pots. This is one of the least studied of the large Diptera families, probably due to the small size of these insects and the similarity among species. Currently, around 1700 species are described, but an estimated 20,000 species are awaiting discovery, mainly in the tropics. More than 600 species are known from Europe. Description Adult Sciaridae are small, dark flies 1-11 mm long and usually <5 mm long. They have a characteristic wing venation: there is no cross vein except for a short rs at the wing base, the anterior veins are a short R1 and a long R5, vein M has a simple fork with a long stem, and CuA1 has a fork with a short stem. Larval Sciaridae are slender and lack legs. They are white except for a black head, and their skin is slightly transpa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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