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Phytophthora Megakarya
''Phytophthora megakarya'' is an oomycete plant pathogen that causes black pod disease in cocoa trees in west and central Africa. This pathogen can cause detrimental loss of yield in the economically important cocoa industry, worth approximately $70 billion annually. It can damage any part of the tree, causing total yield losses which can easily reach 20-25%. A mixture of chemical and cultural controls, as well as choosing resistant plant varieties, are often necessary to control this pathogen. Hosts and symptoms ''Phytophthora megakaryas only known host is ''Theobroma cacao'', or the cocoa tree, located in West and Central Africa. It is considered to be the most virulent species of ''Phytophthora'' which infects ''T. cacao'', causing the greatest percentage of yield loss. This pathogen causes black pod disease which produces an array of symptoms throughout the host’s life cycle. ''P. megakarya'' is a facultative parasite that can infect any part of the cacao tree at any tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clive Michael Brasier
Clive is a name. People and fictional characters with the name include: People Given name * Clive Allen (born 1961), English football player * Clive Anderson (born 1952), British television, radio presenter, comedy writer and former barrister * Clive Barker (born 1952), English writer, film director and visual artist * Clive Barker (artist, born 1940), British pop artist * Clive Barker (soccer) (born 1944), South African coach * Clive Barnes (1927–2008), English writer and critic, dance and theater critic for ''The New York Times'' * Clive Bell (1881–1964), English art critic * Clive Brook (1887–1974), British film actor * Clive Burr (1957–2013), British musician, former drummer with Iron Maiden * Clive Campbell (footballer), New Zealand footballer in the 1970s and early '80s * Clive Campbell (born 1955), Jamaican-born DJ with the stage name DJ Kool Herc * Clive Clark (golfer) (born 1945), English golfer * Clive Clark (footballer) (1940–2014), English former footballer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametangia
A gametangium (plural: gametangia) is an organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants. In contrast to gametogenesis in animals, a gametangium is a haploid structure and formation of gametes does not involve meiosis. Types of gametangia Depending on the type of gamete produced in a gametangium, several types can be distinguished. Female Female gametangia are most commonly called archegonia. They produce egg cells and are the sites for fertilization. Archegonia are common in algae and primitive plants as well as gymnosperms. In flowering plants, they are replaced by the embryo sac inside the ovule. Male The male gametangia are most commonly called antheridia. They produce sperm cells that they release for fertilization. Antheridia producing non-motile sperm (spermatia) are called spermatangia. Some antheridia do not release their sperm. For example, the oomycete antheridium is a syncytium wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effector (biology)
In biochemistry, an effector molecule is usually a small molecule that selectively binds to a protein and regulates its biological activity. In this manner, effector molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signaling. Effector molecules can also directly regulate the activity of some mRNA molecules (riboswitches). Other examples of effector functions in biochemistry include hormone signaling and immune response. In some cases, specific proteins serve the same role as effector molecules (note: small molecules refers to organic compounds similar in size to amino acids or RNA strands. Most effector molecules are therefor much smaller than individual proteins, which consist of many amino acids). One example of this is in cellular signal transduction cascades. The term ''effector'' is used in other fields of biology. For instance, the effector end of a neuron is the terminus where an axon makes contact with the muscle or o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germinate
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ferns, bacteria, and the growth of the pollen tube from the pollen grain of a seed plant. Seed plants Germination is usually the growth of a plant contained within a seed; it results in the formation of the seedling. It is also the process of reactivation of metabolic machinery of the seed resulting in the emergence of radicle and plumule. The seed of a vascular plant is a small package produced in a fruit or cone after the union of male and female reproductive cells. All fully developed seeds contain an embryo and, in most plant species some store of food reserves, wrapped in a seed coat. Some plants produce varying numbers of seeds that lack embryos; these are empty seeds which never germinate. Dormant seeds are viable seeds that do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenesis
Pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Greek πάθος ''pathos'' 'suffering, disease' and γένεσις ''genesis'' 'creation'. Description Types of pathogenesis include microbial infection, inflammation, malignancy and tissue breakdown. For example, bacterial pathogenesis is the process by which bacteria cause infectious illness. Most diseases are caused by multiple processes. For example, certain cancers arise from dysfunction of the immune system (skin tumors and lymphoma after a renal transplant, which requires immunosuppression), Streptococcus pneumoniae is spread through contact with respiratory secretions, such as saliva, mucus, or cough droplets from an infected person and colonizes the upper respiratory tract and begins to multiply. The pathogenic mechanisms of a disease (or cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyst
A microbial cyst is a resting or dormant stage of a microorganism, usually a bacterium or a protist or rarely an invertebrate animal, that helps the organism to survive in unfavorable environmental conditions. It can be thought of as a state of suspended animation in which the metabolic processes of the cell are slowed and the cell ceases all activities like feeding and locomotion. Encystment, the formation of the cyst, also helps the microbe to disperse easily, from one host to another or to a more favorable environment. When the encysted microbe reaches an environment favorable to its growth and survival, the cyst wall breaks down by a process known as excystation. In excystment, the exact stimulus is unknown for most protists. Unfavorable environmental conditions such as lack of nutrients or oxygen, extreme temperatures, lack of moisture and presence of toxic chemicals, which are not conducive for the growth of the microbeEugene W. Nester, Denise G. Anderson, C. Evans Roberts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mycelium
Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrate (biology), substrates. A typical single spore germinates into a Monokaryon, monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form sporocarp (fungi), fruiting bodies such as mushrooms. A mycelium may be minute, forming a colony that is too small to see, or may grow to span thousands of acres as in ''Armillaria''. Through the mycelium, a fungus absorbs nutrients from its environment. It does this in a two-stage process. First, the hyphae secrete enzymes onto or into the food source, which break down biopolymers, biological polymers into smaller units such as monomers. These monomers are then absorbed into the mycelium by facilitated diffusion and active transport. Mycelia are v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mating Type
Mating types are the microorganism equivalent to sexes in multicellular lifeforms and are thought to be the ancestor to distinct Sex, sexes. They also occur in macro-organisms such as fungi. Definition Mating types are the microorganism equivalent to sex in higher organisms and occur in isogamy, isogamous and anisogamous species. Depending on the group, different mating types are often referred to by numbers, letters, or simply "+" and "−" instead of "male" and "female", which refer to "Sex, sexes" or differences in size between gametes. Syngamy can only take place between gametes carrying different mating types. Occurrence Reproduction by mating types is especially prevalent in Fungus, fungi. Filamentous ascomycetes usually have two mating types referred to as "MAT1-1" and "MAT1-2", following the yeast mating-type locus (MAT). Under standard nomenclature, MAT1-1 (which may informally be called MAT1) encodes for a regulatory protein with an alpha box motif, while MAT1-2 (informal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterothallic
Heterothallic species have sexes that reside in different individuals. The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of sexual reproduction from a single organism. In heterothallic fungi, two different individuals contribute nuclei to form a zygote. Examples of heterothallism are included for ''Saccharomyces cerevisiae, Aspergillus fumigatus, Aspergillus flavus'', ''Penicillium marneffei'' and ''Neurospora crassa''. The heterothallic life cycle of ''N. crassa'' is given in some detail, since similar life cycles are present in other heterothallic fungi. Life cycle of ''Saccharomyces cerevisiae'' The yeast ''Saccharomyces cerevisiae'' is heterothallic. This means that each yeast cell is of a certain mating type and can only mate with a cell of the other mating type. During vegetative growth that ordinarily occurs when nutrients are abundant, ''S. cerev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oospore
An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes. They are believed to have evolved either through the fusion of two species or the chemically-induced stimulation of mycelia, leading to oospore formation. In Oomycetes, oospores can also result from asexual reproduction, by apomixis In botany, apomixis is asexual reproduction without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttin .... These are found in fungi as sexual spores which help the sexual reproduction of fungi. These haploid, non-motile spores are the site of meiosis and karyogamy in oomycetes. A dormant oospore, when observed under an electron microscope, has led researchers to draw conclusion that there is only a single central globule with other storage bodies surrounding it. References Reproducti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlamydospore
A chlamydospore is the thick-walled large resting spore of several kinds of fungi, including Ascomycota such as '' Candida'', Basidiomycota such as ''Panus'', and various Mortierellales species. It is the life-stage which survives in unfavourable conditions, such as dry or hot seasons. ''Fusarium oxysporum'' which causes the plant disease Fusarium wilt is one which forms chlamydospores in response to stresses like nutrient depletion. Mycelia of the pathogen can survive in this manner and germinate in favorable conditions. Chlamydospores are usually dark-coloured, spherical, and have a smooth (non-ornamented) surface. They are multicellular, with cells connected by pores in the septae between cells. Chlamydospores are a result of asexual reproduction (in which case they are conidia called chlamydoconidia) or sexual reproduction (rare). Teliospores are special kind of chlamydospores formed by rusts and smuts. File:Candida pseudohyphae, chlamydospores, blastospores.png, Pseudohy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or more distinct types of flagella - tinsel or "decorated", and whiplash, in various combinations. *Tinsellated (straminipilous) flagella have lateral filaments known as mastigonemes perpendicular to their main axis, which allow for more surface area, and disturbance of the medium, giving them the property of a rudder, that is, used for steering. *Whiplash flagella are straight, to power the zoospore through its medium. Also, the "default" zoospore only has the propelling, whiplash flagella. Both tinsel and whiplash flagella beat in a sinusoidal wave pattern, but when both are present, the tinsel beats in the opposite direction of the whiplash, to give two axes of control of motility. Morphological types In eukaryotes, the four main types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
