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Gray-tailed Vole
The gray-tailed vole (''Microtus canicaudus'') also known as the gray-tailed meadow vole or gray-tailed meadow mouse, is a rodent in the genus ''Microtus'' (small-eared "meadow voles") of the family Cricetidae. Voles are small mammals, and this species lies roughly in the middle of their size range. First collected in 1895, it is endemic to the Willamette Valley, Oregon, and Clark County, Washington, in the Pacific Northwest region of North America. Historically, they were found in the prairie areas of the Valley and, though many of these areas have been converted for agricultural purposes, these animals remain common. For reasons that remain unclear, vole population densities in any area may fluctuate widely from season to season and year to year. They are preyed upon by owls, hawks, and carnivorous mammals, and their parasites include fleas and ticks. These voles build burrows and complex tunnel networks, which they sometimes share with other burrowing animals. Relatively littl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerrit S
Gerrit is a Dutch male name meaning "''brave with the spear''", the Dutch and Frisian form of Gerard. People with this name include: * Gerrit Achterberg (1905–1962), Dutch poet * Gerrit van Arkel (1858–1918), Dutch architect * Gerrit Badenhorst (born 1962), South African powerlifter and professional strongman competitor * Gerrit Battem (c. 1636 – 1684), Dutch landscape painter * Gerrit Beneker (1882–1934), American painter and illustrator * Gerrit Berckheyde (1638–1698), Dutch painter * Gerrit Berkhoff (1901–1996), Dutch chemist and university rector * Gerrit Cornelis Berkouwer (1903–1996), Dutch theologian * Gerrit Berveling (born 1944), Dutch Esperanto author * Gerrit Blaauw (born 1924), Dutch computer engineer * Gerrit de Blanken (1894–1961), Dutch pottery artist * Gerrit van Bloclant (1578–1650), Dutch Renaissance painter * Gerrit Bol (1906–1989), Dutch mathematician * Gerrit Braamcamp (1699–1771), Dutch distiller, timber merchant and art collector * G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montane Vole
The montane vole (''Microtus montanus'') is a species of vole native to the western United States and Canada. Description Montane voles are medium-sized voles, with a total length of , including the tail. Adults typically weigh anything from , with males being slightly larger than females, but the actual weight varies considerably with age, geography, and subspecies. The upper body is covered with fur of a dark brownish shade, again with some variation between individuals. The fur is paler on the flanks, and fades to grey or white on the underparts. The tail exhibits the same color variation, with the fur being dark brown to almost black on the upper surface and grey or white below. Montane voles possess scent glands on the hips, near the anus, and on the male genitalia. These glands increase in size in response to testosterone, and are therefore particularly large in adult males. At least some of these glands produce unique fatty acid esters, that may function in species recogn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gresham, Oregon
Gresham ( ) is a city located in Multnomah County, Oregon, in the United States of America, immediately east of Portland, Oregon. It is considered a suburb within the Greater Portland Metropolitan area. Though it began as a settlement in the mid-1800s, it was not officially incorporated as a city until 1905; it was named after Walter Quintin Gresham, the American Civil War general and United States Secretary of State. The city's early economy was sustained largely by farming, and by the mid-20th century the city experienced a population boom, growing from 4,000 residents to over 10,000 between 1960 and 1970. The population was 105,594 at the 2010 census, making Gresham the fourth largest city in Oregon. History The area now known as Gresham was first settled in 1851 by brothers Jackson and James Powell, who claimed land under the Donation Land Claim Act of 1850. They were soon joined by other pioneer families, and the area came to be known as Powell's Valley. In 1884, a local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scappoose, Oregon
Scappoose is a city in Columbia County, Oregon, United States. It was named for a nearby stream, which drains the southern part of the county. The name "Scappoose" is of Native American origin, and is said to mean "gravelly plain."A 1940 Journey Across Oregon: Portland to Rainier Archivist of the State of Oregon. Retrieved on 2008-05-29. The population was 6,592 at the 2010 census. Government The Mayor is elected for a two-year term and is chair of the City Council. The City Manager supervisions and general management of all City operations and ensures that Council policy is carried out and that laws and municipal code are in c ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creeping Vole
The creeping vole (''Microtus oregoni''), sometimes known as the Oregon meadow mouse, is a small rodent in the family Cricetidae. Ranging across the Pacific Northwest of North America, it is found in forests, grasslands, woodlands, and chaparral environments. The small-tailed, furry, brownish-gray mammal was first described in the scientific literature in 1839, from a specimen collected near the mouth of the Columbia River. The smallest vole in its range, it weighs around . At birth, they weigh , are naked, pink, unable to open their eyes, and the ear flaps completely cover the ear openings. Although not always common throughout their range, there are no major concerns for their survival as a species. Taxonomy The animal was described in 1839 by John Bachman. The original scientific name was ''Arvicola oregoni'' with a common name of the Oregon meadow mouse. The type specimen was an older male collected November 2, 1836 near the mouth of the Columbia River in Oregon. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incisive Foramina
In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood vessels and nerves. The incisive foramen is situated within the incisive fossa of the maxilla. The incisive foramen is used as an anatomical landmark for defining the severity of cleft lip and cleft palate. The incisive foramen exists in a variety of species. Structure The incisive foramen is a funnel-shaped opening of the in the bone of the oral hard palate representing the inferior termination of the incisive canal. An oral prominence - the incisive papilla - overlies the incisive fossa. The incisive foramen is situated immediately behind the incisor teeth, and in between the two premaxillae. Contents The incisive foramen allows for blood vessels and nerves to pass. These include: * the pterygopalatine nerves to the hard palate. * t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Palate
The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans the alveolar process, alveolar arch formed by the alveolar process that holds the upper teeth (when these are developed). Structure The hard palate is formed by the palatine process of the maxilla and horizontal plate of palatine bone. It forms a partition between the nasal passages and the mouth. On the anterior portion of the hard palate are the plicae, irregular ridges in the mucous membrane that help facilitate the movement of food backward towards the larynx. This partition is continued deeper into the mouth by a fleshy extension called the soft palate. On the ventral surface of hard palate, some projections or transverse ridges are present which are called as palatine rugae. Function The hard palate is important for feeding and sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation – which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow – that results in genetic divergence. Sympatric speciation may, but need not, arise through secondary contact, which refers to speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed. Types of populations Four main types of population pairs exist in nature. Sympatric populations (or species) contrast with parapatric populations, which contact one another in adjacent but not shared ranges and do no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopatric
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterochromatin
Heterochromatin is a tightly packed form of DNA or '' condensed DNA'', which comes in multiple varieties. These varieties lie on a continue between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a role in the expression of genes. Because it is tightly packed, it was thought to be inaccessible to polymerases and therefore not transcribed; however, according to Volpe et al. (2002), and many other papers since, much of this DNA is in fact transcribed, but it is continuously turned over via RNA-induced transcriptional silencing (RITS). Recent studies with electron microscopy and OsO4 staining reveal that the dense packing is not due to the chromatin. Constitutive heterochromatin can affect the genes near itself (e.g. position-effect variegation). It is usually repetitive and forms structural functions such as centromeres or telomeres, in addition to acting as an attractor for other gene-expression or repression signals. Facultative hete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomal
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. For example, humans have a diploid human genome, genome that usually contains 22 pairs of autosomes and one allosome pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY syndrome, XYY, Klinefelter syndrome, XXY, Triple X syndrome, XXX, XXXX syndrome, XXXX, XXXXX syndrome, XXXXX or XXYY syndrome, XXYY, among Aneuploidy, other Salome combinations, are known to occur and usually cause developmental abnormalities. Autosomes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
