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Axarus
The genus ''Axarus'' is widely distributed with records from the Holarctic, the Neotropics and Australasia . There are currently 5 described nearctic species . Erected as a subgenus (''Anceus'') of ''Xenochironomus'' , ''Axarus'' was subsequently renamed and elevated to generic status . The Connecticut River in the eastern United States harbors locally dense populations of two ''Axarus'' species, both currently undescribed. These populations are interesting in that they are restricted to specific larval habitat (varve clay and sometimes rotting wood) and thus there is genetic structure between populations in the river . The Connecticut River species are also notable in that they have extremely well developed polytene chromosomes and also maintain a high degree of inversion polymorphism . Species *'' A. dorneri'' ( Malloch, 1915) *'' A. festivus'' Say, 1823 *'' A. rogersi'' (Beck and Beck, 1958) *'' A. scopula'' (Townes, 1945) *'' A. taenionotus'' (Sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axarus Taenionotus
The genus ''Axarus'' is widely distributed with records from the Holarctic, the Neotropics and Australasia . There are currently 5 described nearctic species . Erected as a subgenus (''Anceus'') of ''Xenochironomus'' , ''Axarus'' was subsequently renamed and elevated to generic status . The Connecticut River in the eastern United States harbors locally dense populations of two ''Axarus'' species, both currently undescribed. These populations are interesting in that they are restricted to specific larval habitat ( varve clay and sometimes rotting wood) and thus there is genetic structure between populations in the river . The Connecticut River species are also notable in that they have extremely well developed polytene chromosomes and also maintain a high degree of inversion polymorphism . Species *'' A. dorneri'' ( Malloch, 1915) *'' A. festivus'' Say, 1823 *'' A. rogersi'' (Beck and Beck, 1958) *'' A. scopula'' (Townes, 1945) *'' A. taenionotus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axarus Scopula
The genus ''Axarus'' is widely distributed with records from the Holarctic, the Neotropics and Australasia . There are currently 5 described nearctic species . Erected as a subgenus (''Anceus'') of ''Xenochironomus'' , ''Axarus'' was subsequently renamed and elevated to generic status . The Connecticut River in the eastern United States harbors locally dense populations of two ''Axarus'' species, both currently undescribed. These populations are interesting in that they are restricted to specific larval habitat ( varve clay and sometimes rotting wood) and thus there is genetic structure between populations in the river . The Connecticut River species are also notable in that they have extremely well developed polytene chromosomes and also maintain a high degree of inversion polymorphism . Species *'' A. dorneri'' ( Malloch, 1915) *'' A. festivus'' Say, 1823 *'' A. rogersi'' (Beck and Beck, 1958) *'' A. scopula'' (Townes, 1945) *'' A. taenionotus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axarus Rogersi
The genus ''Axarus'' is widely distributed with records from the Holarctic, the Neotropics and Australasia . There are currently 5 described nearctic species . Erected as a subgenus (''Anceus'') of ''Xenochironomus'' , ''Axarus'' was subsequently renamed and elevated to generic status . The Connecticut River in the eastern United States harbors locally dense populations of two ''Axarus'' species, both currently undescribed. These populations are interesting in that they are restricted to specific larval habitat ( varve clay and sometimes rotting wood) and thus there is genetic structure between populations in the river . The Connecticut River species are also notable in that they have extremely well developed polytene chromosomes and also maintain a high degree of inversion polymorphism . Species *'' A. dorneri'' ( Malloch, 1915) *'' A. festivus'' Say, 1823 *'' A. rogersi'' (Beck and Beck, 1958) *'' A. scopula'' (Townes, 1945) *'' A. taenionotus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axarus Dorneri
The genus ''Axarus'' is widely distributed with records from the Holarctic, the Neotropics and Australasia . There are currently 5 described nearctic species . Erected as a subgenus (''Anceus'') of ''Xenochironomus'' , ''Axarus'' was subsequently renamed and elevated to generic status . The Connecticut River in the eastern United States harbors locally dense populations of two ''Axarus'' species, both currently undescribed. These populations are interesting in that they are restricted to specific larval habitat ( varve clay and sometimes rotting wood) and thus there is genetic structure between populations in the river . The Connecticut River species are also notable in that they have extremely well developed polytene chromosomes and also maintain a high degree of inversion polymorphism . Species *'' A. dorneri'' ( Malloch, 1915) *'' A. festivus'' Say, 1823 *'' A. rogersi'' (Beck and Beck, 1958) *'' A. scopula'' (Townes, 1945) *'' A. taenionotus'' ... [...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] |
Chromosomal Inversion
An inversion is a chromosome rearrangement in which a segment of a chromosome becomes inverted within its original position. An inversion occurs when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm. The breakpoints of inversions often happen in regions of repetitive nucleotides, and the regions may be reused in other inversions. Chromosomal segments in inversions can be as small as 100 kilobases or as large as 100 megabases. The number of genes captured by an inversion can range from a handful of genes to hundreds of genes. Inversions can happen either through ectopic recombination, chromosomal breakage and repair, or non-homologous end joining. Inversions are of two types: paracentric and pericentric. Paracentric inversions do not include the centromere, and both breakpoints occur in one arm of the chromosome. Pericentric inversions span the centromere, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connecticut River
The Connecticut River is the longest river in the New England region of the United States, flowing roughly southward for through four states. It rises 300 yards (270 m) south of the U.S. border with Quebec, Canada, and discharges at Long Island Sound. Its watershed encompasses , covering parts of five U.S. states and one Canadian province, via 148 tributaries, 38 of which are major rivers. It produces 70% of Long Island Sound's fresh water, discharging at per second. The Connecticut River Valley is home to some of the northeastern United States' most productive farmland, as well as the Hartford–Springfield Knowledge Corridor, a metropolitan region of approximately two million people surrounding Springfield, Massachusetts, and Hartford, Connecticut. History The word "Connecticut" is a corruption of the Mohegan word ''quinetucket'', which means "beside the long, tidal river". The word came into English during the early 1600s to name the river, which was also called simply "Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varve
A varve is an annual layer of sediment or sedimentary rock. The word 'varve' derives from the Swedish word ''varv'' whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as ''Hvarfig lera'' (varved clay) on the first map produced by the Geological Survey of Sweden in 1862. Initially, "varve" referred to each of the separate components comprising a single annual layer in glacial lake sediments, but at the 1910 Geological Congress, the Swedish geologist Gerard De Geer (1858–1943) proposed a new formal definition, where varve means the whole of any annual sedimentary layer. More recently introduced terms such as 'annually laminated' are synonymous with varve. Of the many rhythmites in the geological record, varves are one of the most important and illuminating in studies of past climate change. Varves are amongst the smallest-scale events recognised in stratigraphy. An annual layer can be highly visible because the particles wash ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Research
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated (S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called sis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entomological News
Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arachnids, myriapods, and crustaceans. This wider meaning may still be encountered in informal use. Like several of the other fields that are categorized within zoology, entomology is a taxon-based category; any form of scientific study in which there is a focus on insect-related inquiries is, by definition, entomology. Entomology therefore overlaps with a cross-section of topics as diverse as molecular genetics, behavior, neuroscience, biomechanics, biochemistry, systematics, physiology, developmental biology, ecology, morphology, and paleontology. Over 1.3 million insect species have been described, more than two-thirds of all known species. Some insect species date back to around 400 million years ago. They have many kinds of intera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neotropics
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropics, tropical Ecoregion#Terrestrial, terrestrial ecoregions of the Americas and the entire South American temperate climate, temperate zone. Definition In biogeography, the Neotropic or Neotropical realm is one of the eight terrestrial realms. This realm includes South America, Central America, the Caribbean islands, and southern North America. In Mexico, the Yucatán Peninsula and southern lowlands, and most of the east and west coastlines, including the southern tip of the Baja California Peninsula are Neotropical. In the United States southern Florida and coastal Central Florida are considered Neotropical. The realm also includes temperate southern South America. In contrast, the Neotropical Phytochorion, Floristic Kingdom excludes southernmost South America, which instead is placed in the Antarctic Floristic Kingdom, Antarctic kingdom. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
