|
Trypanotolerance
A trypanotolerant organism is one which is disease tolerance, relatively less affected by trypanosoma, trypanosome infestation. By host In livestock Some breeds are known for their trypanotolerance. This is especially important in Africa where a Animal trypanosomiasis, few particular trypanosomes are major economic and agricultural pest (organism), pests. Trypanotolerant livestock breeds * N'Dama cattle * West African Dwarf goats * West African Dwarf sheep (Djallonké) * Cameroon sheep Trypanotolerance of the N'Dama Cattle and West African Dwarf Sheep and Goats Certain domestic ruminant breeds in sub-saharan Africa show remarkable resistance to the effects of African trypanosomiasis: they can tolerate the parasites's presence while controlling parasitaemia levels and, most importantly, do not show the severe anemia and production loss that are typical of infection in susceptible breeds. The trypanotolerance trait is seen in N'Dama cattle, and it refers to the N'Dama ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morris Soller
Morris Soller (; born 1931) is an American-Israeli research professor in the Department of Genetics of the Hebrew University of Jerusalem. He is especially interested in livestock genetics, livestock- and crop genetics, crop- genetics including trypanotolerance in cattle. Early life and education Soller was born in Manhattan, New York City in 1931. At the age of 12 he was first inspired to learn about genetics by reading The Theory of the Gene by Thomas Hunt Morgan. . While an undergraduate he read Jay Laurence Lush's ''Animal Breeding Plans'' and learned much from it and would receive the award named for Lush 50 years later see below. Soller also learned much from the writings of Ronald Fisher and Sewall Wright during this time. In 1951 he earned a Bachelor's Degree in Agriculture and then in 1956 both a Master's Degree in applied statistics, Applied Statistics and a Doctorate of Philosophy in animal breeding, Animal Breeding from Rutgers University. He would later return to his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N'Dama Cattle
N'Dama is a breed of cattle from West Africa. Other names for them include Boenca or Boyenca (Guinea-Bissau), Fouta Jallon, ''Djallonké'' or ''Djallonké cattle'', Fouta Longhorn, Fouta Malinke, Futa, Malinke, Mandingo (Liberia), and N'Dama Petite (Senegal). Originating in the Guinea highlands, they are also found in southern Senegal, Guinea-Bissau, the Gambia, Mali, Ivory Coast, Liberia, Nigeria, and Sierra Leone. They are trypanotolerant, allowing them to be kept in tsetse fly-infested areas. They also show superior resistance to ticks and the diseases they carry and to ''Haemonchus contortus'' stomach worms. The Senepol breed of beef cattle developed on the Caribbean Island of St. Croix was long thought to originate from crosses between N'Dama cattle, imported in the late 19th century, and Red Poll cattle, but it is actually an admixed breed between a European taurina (Red Poll) and zebu. Reproduction The age of first calving is 3.5 years in Upper Casamance and is slightly l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West African Dwarf Sheep
The West African Dwarf or Djallonké is an African breed or group of breeds of domestic sheep. It is the dominant breed of West and Central Africa. This breed is primarily raised for meat. The Cameroon or Cameroon Dwarf is a breed within this group.Valerie Porter, Lawrence Alderson, Stephen J.G. Hall, D. Phillip Sponenberg (2016)''Mason's World Encyclopedia of Livestock Breeds and Breeding''(sixth edition). Wallingford: CABI. . Characteristics The West African Dwarf is generally white or piebald, the front half being black and the back half white. However, skewbald (tan on white) and the black belly pattern are found, and the Kirdi type are specially selected to be entirely black. Rams weigh approximately , have a well-developed throat ruff and are usually horned. The horns are wide at the base, curve backwards, outwards and then forwards again, with a maximum of one and a half coils. Ewes weigh about and are usually polled (hornless), but may have slender short horns. The ears a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trypanosoma
''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (borer) and ''soma'' (body) because of their corkscrew-like motion. Most trypanosomes are heteroxenous (requiring more than one obligatory host to complete life cycle) and most are transmitted via a vector. The majority of species are transmitted by blood-feeding invertebrates, but there are different mechanisms among the varying species. '' Trypanosoma equiperdum'' is spread between horses and other equine species by sexual contact. They are generally found in the intestine of their invertebrate host, but normally occupy the bloodstream or an intracellular environment in the vertebrate host. Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases sleeping sickness, caused by '' Trypanosoma br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Resilience
In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or Disturbance (ecology), disturbance by resisting damage and subsequently recovering. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms, insect population explosions, and human activities such as deforestation, fracking of the ground for oil extraction, pesticide sprayed in soil, and the Introduced species, introduction of exotic plant or animal species. Disturbances of sufficient Magnitude (mathematics), magnitude or duration can profoundly affect an ecosystem and may force an ecosystem to reach a Ecological threshold, threshold beyond which a different regime of processes and structures predominates. When such thresholds are associated with a critical or bifurcation theory, bifurcation point, these regime shifts may also be referred to as critical transitions. Human activities that adversely affect ecological resilience such as loss of biodiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resistance (ecology)
In the context of ecological stability, resistance is the property of community (ecology), communities or populations to remain "essentially unchanged" when subject to disturbance (ecology), disturbance. The inverse of resistance is sensitivity. Stability and disturbance Resistance is one of the major aspects of ecological stability. Volker Grimm and Christian Wissel identified 70 terms and 163 distinct definitions of the various aspects of ecological stability, but found that they could be reduced to three fundamental properties: "staying essentially unchanged", "returning to the reference state...after a temporary disturbance" and "persistence through time of an ecological system." Resistant communities are able to remain "essentially unchanged" despite disturbance. Although commonly seen as distinct from resilience (ecology), resilience, Brian Walker (ecologist), Brian Walker and colleagues considered resistance to be a component of resilience in their expanded definition of resi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunological
Immunology is a branch of biology and medicine that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoimmune diseases, hypersensitivities, immune deficiency, and transplant rejection); and the physical, chemical, and physiological characteristics of the components of the immune system ''in vitro'', '' in situ'', and '' in vivo''. Immunology has applications in numerous disciplines of medicine, particularly in the fields of organ transplantation, oncology, rheumatology, virology, bacteriology, parasitology, psychiatry, and dermatology. The term was coined by Russian biologist Ilya Ilyich Mechnikov, who advanced studies on immunology and received the Nobel Prize for his work in 1908 with Paul Ehrlich "in recognition of their work on immunity". He pinned small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dose (biochemistry)
A dose is a measured quantity of a medicine, nutrient, or pathogen that is delivered as a unit. The greater the quantity delivered, the larger the dose. Doses are most commonly measured for compounds in medicine. The term is usually applied to the quantity of a drug or other agent administered for therapeutic purposes, but may be used to describe any case where a substance is introduced to the body. In nutrition, the term is usually applied to how much of a specific nutrient is in a person's diet or in a particular food, meal, or dietary supplement. For bacterial or Virus, viral agents, dose typically refers to the amount of the pathogen required to infect a host. In clinical pharmacology, ''dose'' refers to the amount of drug administered to a person, and Dosage (pharmacology), ''dosage'' is a fuller description that includes not only the dose (e.g., "500 mg") but also the frequency and duration of the treatment (e.g., "twice a day for one week"). Exposure assessment, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease Tolerance
Tolerance to infection, or disease tolerance, is a mechanism that host organisms can use to fight parasites or pathogens that attack the host. Tolerance is not equivalent to resistance. Disease resistance is the host trait that prevents infection or reduces the number of pathogens and parasites within or on a host. Tolerance to infection can be illustrated via comparing host performance versus increasing load. This is a reaction norm in which host performance is regressed against increasing disease burden. The slope of the reaction norm defines the degree of tolerance. High tolerance is indicated as a flat slope, i.e., host performance is not influenced by increasing burden. Steep downward slope indicates low tolerance in which host performance is strongly reduced with increasing burden. An upward slope indicates overcompensation in which a host increases its performance with increasing burden. Genetic variation in tolerance and its correlation with resistance, can be quantified usi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess or thought. If a hypothesis is repeatedly independently demonstrated by experiment to be true, it becomes a scientific theory. In colloquial usage, the words "hypothesis" and "theory" are often used interchangeably, but this is incorrect in the context of science. A working hypothesis is a provisionally-accepted hypothesis used for the purpose of pursuing further progress in research. Working hypotheses are frequently discarded, and often proposed with knowledge (and warning) that they are incomplete and thus false, with the intent of moving research in at least somewhat the right direction, especially when scientists are stuck on an issue and brainstorming ideas. A different meaning of the term ''hypothesis'' is used in formal l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sheep
Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated sheep. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. An adult female is referred to as a ''ewe'' ( ), an intact male as a ''ram'', occasionally a ''tup'', a castrated male as a ''wether'', and a young sheep as a ''lamb''. Sheep are most likely descended from the wild mouflon of Europe and Asia, with Iran being a geographic envelope of the domestication center. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces, meat ( lamb, hogget or mutton), and milk. A sheep's wool is the most widely used animal fiber, and is usually harvested by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
