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Pasteuria Ramosa
''Pasteuria ramosa'' is a gram-positive, endospore-forming bacterium in the Bacillus/Clostridia clade within Bacillota. It is an obligate pathogen of cladoceran crustaceans from the genus ''Daphnia''. Daphnia is an umbrella term for a number of small freshwater creatures including '' D. magna, P. ramosa'''s most popular host target''.'' Other hosts include D. pulex'', D. longispina'', '' D. dentifera'', and '' Moina rectirostris''. An established and widely used coevolutionary model of host-pathogen interactions exists with ''P. ramosa'' and '' D. magna. Growth and sporulation ''P. ramosa'' is an obligate pathogen and it can only grow inside its host. Transmission between hosts takes place through the endospore stage, and is strictly horizontal. These endospores are highly resistant to different environmental stresses, including freezing temperatures, and can remain in the environment for decades without any deleterious effects. The infection can be explained in 5 steps: (1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic relationsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Pulex
''Daphnia pulex'' is the most common species of water flea. It has a cosmopolitan distribution: the species is found throughout the Americas, Europe, and Australia. It is a model species, and was the first crustacean to have its genome sequenced. Description ''D. pulex'' is an arthropod whose body segments are difficult to distinguish. It can only be recognised by its appendages (only ever one pair per segment), and by studying its internal anatomy. The head is distinct and is made up of six segments, which are fused together even as an embryo. It bears the mouthparts, and two pairs of antennae, the second pair of which is enlarged into powerful organs used for swimming. No clear division is seen between the thorax and abdomen, which collectively bear five pairs of appendages. The shell surrounding the animal extends posteriorly into a spine. Like most other ''Daphnia'' species, ''D. pulex'' reproduces by cyclical parthenogenesis, alternating between sexual and asexual reprodu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Transmission
Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. This concept has been generalized to include transmissions of infectious agents, symbionts, and cultural traits between humans. Because the evolutionary fate of the agent is not tied to reproductive success of the host, horizontal transmission tends to evolve virulence. It is therefore a critical concept for evolutionary medicine. Biological Pathogen transmission In biological, but not cultural, transmissions the carriers (also known as vectors) may include other species. The two main biological modes of transmission are ''anterior station'' and ''posterior station''. In anterior station, transmission occurs via the bite of an infected organism (the vector), like in malaria, dengue fever, and bubonic plague. Posterior station is transmission via contact with infected feces. Examples are rickettsiae driven diseases (l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endospores
An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form (''endo'' means 'within'), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is usually triggered by a lack of nutrients, and usually occurs in gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall, and one side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries. There are many reports of spores remaining viable over 10,000 years, and revival of spores millions of years old has been claimed. There is one report of viable spores of ''Bacillus marismortui'' in salt crystals approximately 250 million years old. When the environment becomes more favorable, the endospore can reactivate itself into a vegetative state. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obligate
{{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym ''facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe, an organism that cannot survive without oxygen * Obligate anaerobe, an organism that cannot survive in the presence of oxygen * Obligate air-breather, a term used in fish physiology to describe those that respire entirely from the atmosphere * Obligate biped, Bipedalism designed to walk on two legs * Obligate carnivore, an organism dependent for survival on a diet of animal flesh. * Obligate hibernation, a state of inactivity in which some organisms survive conditions of insufficiently available resources. * Obligate intracellular parasite, a parasitic microorganism that cannot reproduce without entering a suitable host cell * Obligate parasite, a parasite that cannot reproduce without exploiting a suitable host * Obligate photoperiodic plant, a plant that requires sufficiently long or short nights before it initiates flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pasteuria Ramosa Endospores
''Pasteuria'' is a genus of mycelial and endospore-forming, nonmotile gram-positive bacteria that are obligate parasites of some nematodes and crustaceans. The genus of ''Pasteuria'' was previously classified within the family Alicyclobacillaceae, but has since been moved to the family Pasteuriaceae. Steps of infection Animals that are susceptible to ''Pasteuria'' become infected when they are exposed to spores in soil or water. Therefore, ''Pasteuria'' are transmitted horizontally between hosts and when an infected host dies, it releases spores to the soil or sediment. The likelihood of infections is related to the spore density in the environment and can be affected by temperature. After contact with the host, ''Pasteuria'' spores are activated, attach to their host, penetrate the host's cuticle, proliferate within the host, and kill the host. In water fleas, the ability of the spore to successfully attach during the infection process is related to the genotype of the host ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coevolution
In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well as gene-culture coevolution. Charles Darwin mentioned evolutionary interactions between flowering plants and insects in ''On the Origin of Species'' (1859). Although he did not use the word coevolution, he suggested how plants and insects could evolve through reciprocal evolutionary changes. Naturalists in the late 1800s studied other examples of how interactions among species could result in reciprocal evolutionary change. Beginning in the 1940s, plant pathologists developed breeding programs that were examples of human-induced coevolution. Development of new crop plant varieties that were resistant to some diseases favored rapid evolution in pathogen populations to overcome those plant defenses. That, in turn, required the development of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moina Rectirostris
''Moina'' is a genus of crustaceans within the family Moinidae. The genus was first described by W. Baird in 1850. They are referred to as water fleas, but are related to the much larger ''Daphnia magna'' and the larger ''Daphnia pulex''. This genus demonstrates the ability to survive in waters containing low oxygen levels, high salinity, and other impurities, including salt pans, and commonly eutrophication. An example of such an extreme habitat is the highly saline Makgadikgadi Pans of Botswana, which supports prolific numbers of ''Moina belli''. The ''Moina'' are known to be found in various types of bodies of water in Eurasia where new found research indicates that there is an increased presence of biodiversity in regions of Northern Eurasia, Japan and China. There is an increase of new phylogroups found in Northern Eurasia, an increase of 4 new ''Moina'' species in Japan and an increase of five new lineages in China. Species ''Moina'' contains these species: * ''M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Longispina
''Daphnia longispina'' is a planktonic crustacean of the family Daphniidae, a cladoceran freshwater water flea. It is native to Eurasia. ''D. longispina'' is similar in size and sometimes confused with the often sympatric '' D. pulex'' (a very common species), but much smaller than '' D. magna''. ''D. longispina'' is found in a wide range of standing freshwater bodies from small, ephemeral rock-pools to large lakes. Life history Like all ''Daphnia'' species, ''D. longispina'' is a filter feeder, collecting particles of about 2 to 40 µm suspended in the water. The main food are green algae. At 20 °C maturity is reached within about 6 to 12 days, followed by a period of regular reproduction in about 3-4 day intervals. ''D. longispina'' reproduces either asexually (''parthenogenesis'') or sexually. For the later, females need to produce sons asexually. The same or other females can switch at any moment from asexual to sexual reproduction, but producing haploid eggs, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Magna
''Daphnia magna'' is a small planktonic crustacean (adult length 1.5–5.0 mm) that belongs to the subclass Phyllopoda. Description ''D. magna'' is a typical water flea of the genus ''Daphnia''. The females reach up to 5 mm in size, the males about 2 mm, thus they are among the largest species in the genus. The body is protected by a translucent carapace made of chitin, a transparent polysaccharide. It has a ventral opening and five pairs of thoracic limbs, used to help the filtering process. Spike rows run along the back of the carapace. The intestine is hook-shaped and has two digestive ceca. The head has two antennae and a large compound eye. Adult females can be distinguished from those of otherwise similar species such as '' D. pulex'' by the absence of a comb on the abdominal claw and the presence of two distinct combs on the abdomen. The males are smaller than the females and have larger first antennas, a diagnostic feature that distinguishes them from s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillota
The Bacillota (synonym Firmicutes) are a phylum of bacteria, most of which have gram-positive cell wall structure. The renaming of phyla such as Firmicutes in 2021 remains controversial among microbiologists, many of whom continue to use the earlier names of long standing in the literature. The name "Firmicutes" was derived from the Latin words for "tough skin," referring to the thick cell wall typical of bacteria in this phylum. Scientists once classified the Firmicutes to include all gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low- G+C group, in contrast to the Actinomycetota. They have round cells, called cocci (singular coccus), or rod-like forms (bacillus). A few Firmicutes, such as ''Megasphaera'', ''Pectinatus'', ''Selenomonas'' and ''Zymophilus'', have a porous pseudo-outer membrane that causes them to stain gram-negative. Many Bacillota (Firmicutes) produce endospores, which are resistant to desiccation and can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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