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Dikaryon
The dikaryon (karyogamy) is a cell nucleus feature that is unique to certain fungi. (The green alga '' Derbesia'' had been long considered an exception, until the heterokaryotic hypothesis was challenged by later studies.) Compatible cell-types can fuse cytoplasms ( plasmogamy). When this occurs, the two nuclei of two cells pair off and cohabit without fusing ( karyogamy). This can be maintained for all the cells of the hyphae by synchronously dividing so that pairs are passed to newer cells. In the Ascomycota this attribute is most often found in the ascogenous hyphae and ascocarp while the bulk of the mycelium remains monokaryotic. In the Basidiomycota this is the dominant phase, with most Basidiomycota monokaryons weakly growing and short-lived. The formation of a dikaryon is a plesiomorphic character for the subkingdom Dikarya, which consists of the Basidiomycota and the Ascomycota. The formation of croziers in the Ascomycota and of clamp connections in the Basidiomyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dikarya
Dikarya is a subkingdom of Fungi that includes the divisions Ascomycota and Basidiomycota, both of which in general produce dikaryons, may be hypha, filamentous or unicellular, but are always without flagella. The Dikarya are most of the so-called "higher fungi", but also include many anamorphic species that would have been classified as Mold (fungus), molds in historical literature. Phylogenetically the two divisions regularly group together. In a 1998 publication, Thomas Cavalier-Smith referred to this group as the Neomycota. Phylogeny The 2007 classification of Kingdom Fungi is the result of a large-scale collaborative research effort involving dozens of mycologists and other scientists working on fungal Taxonomy (biology), taxonomy. It recognizes seven phylum, divisions within the Fungi, two of which—the Ascomycota and the Basidiomycota—are contained within a branch representing subkingdom Dikarya. The cladogram depicts the major fungal Taxon, taxa and their relationship ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterokaryotic
In biology, a heterokaryon is a multinucleate cell that contains genetically different nuclei. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual reproduction, or artificially as formed by the experimental fusion of two genetically different cells, as e.g., in hybridoma technology. Etymology The term ''heterokaryosis'' for the property of having genetically unlike nuclei is borrowed from the German ''Heterokaryosis'', which was coined by the German botanist Hans Burgeff in a 1912 paper about his work on the fungus '' Phycomyces nitens''. It is based on Greek ''hetero'', meaning "different," and ''karyon'', meaning "kernel" or in this case "nucleus.". Occurrence Heterokaryons are found in the life cycle of yeasts, for example ''Saccharomyces cerevisiae'', a genetic model organism. The heterokaryon stage is produced from the fusion of two haploid cells. This ''transient'' heterokaryon can produce further haploid buds, or ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterokaryon
In biology, a heterokaryon is a multinucleate cell that contains genetically different nuclei. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual reproduction, or artificially as formed by the experimental fusion of two genetically different cells, as e.g., in hybridoma technology. Etymology The term ''heterokaryosis'' for the property of having genetically unlike nuclei is borrowed from the German ''Heterokaryosis'', which was coined by the German botanist Hans Burgeff in a 1912 paper about his work on the fungus '' Phycomyces nitens''. It is based on Greek ''hetero'', meaning "different," and ''karyon'', meaning "kernel" or in this case "nucleus.". Occurrence Heterokaryons are found in the life cycle of yeasts, for example ''Saccharomyces cerevisiae'', a genetic model organism. The heterokaryon stage is produced from the fusion of two haploid cells. This ''transient'' heterokaryon can produce further haploid buds, or c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monokaryon
A monokaryon is a fungal mycelium or hypha in which each cell contains a single nucleus. It also refers to a mononuclear spore or cell of a fungus that produces a dikaryon in its life cycle. Merriam-Webster dictionary See also *Dikaryon
The dikaryon (karyogamy) is a cell nucleus feature that is unique to certain fungi. (The green alga '' Derbesia'' had been long considered an exception, until the heterokaryotic hypothesis was challenged by later studies.) Compatible cell-types c ...
References Mycology {{mycology-stub ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (; : nuclei) is a membrane-bound organelle found in eukaryote, eukaryotic cell (biology), cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have #Anucleated_cells, no nuclei, and a few others including osteoclasts have Multinucleate, many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long strands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are Nuclear organization, structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multinucleated Cells
Multinucleate cells (also known as multinucleated cells or polynuclear cells) are eukaryotic cells that have more than one nucleus, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordinated, synchronous manner where all nuclei divide simultaneously or asynchronously where individual nuclei divide independently in time and space. Certain organisms may have a multinuclear stage of their life cycle. For example, slime molds have a vegetative, multinucleate life stage called a plasmodium. Multinucleate cells, depending on the mechanism by which they are formed, can be divided into "syncytia" (formed by cell fusion) or "coenocytes" (formed by nuclear division not being followed by cytokinesis). Some bacteria, such as ''Mycoplasma pneumoniae'', a pathogen of the respiratory tract, may display multinuclear filaments as a result of a delay between genome replication and cellular division. Terminology Some biologists use the te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binucleated Cells
Binucleated cells are cells that contain two nuclei. This type of cell is most commonly found in cancer cells and may arise from a variety of causes. Binucleation can be easily visualized through staining and microscopy. In general, binucleation has negative effects on cell viability and subsequent mitosis. They also occur physiologically in hepatocytes, chondrocytes and in fungi (dikaryon). Causes * Cleavage furrow regression: Cells divide and almost complete division but then the cleavage furrow begins to regress and the cells merge. This is thought to be caused by nondisjunction in chromosomes but the mechanism by which it occurs is not well understood. * Failed cytokinesis: The cell can fail to form a cleavage furrow, leading to both nuclei remaining in one cell. * Multipolar spindles: Cells contain three or more centrioles, resulting in multiple poles. This leads to the cells pulling chromosomes in many directions that end in multiple nuclei found in one cell. * Mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nut (fruit)
A nut is a fruit consisting of a hard or tough nutshell protecting a kernel which is usually edible. In general usage and in a culinary sense, many dry seeds are called nuts, but in a botanical context, "nut" implies that the shell does not open to release the seed (Dehiscence (botany), indehiscent). Most seeds come from fruits that naturally free themselves from the shell, but this is not the case in nuts such as hazelnuts, chestnuts, and acorns, which have hard shell walls and originate from a compound ovary. Definition A seed is the mature fertilised ovule of a plant; it consists of three parts, the embryo which will develop into a new plant, stored food for the embryo, and a protective seed coat. Botany, Botanically, a nut is a fruit with a woody pericarp developing from a syncarpous gynoecium. Nuts may be contained in an Bract#Involucral bracts, involucre, a cup-shaped structure formed from the flower bracts. The involucre may be scaly, spiny, leafy or tubular, depending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Language
Greek (, ; , ) is an Indo-European languages, Indo-European language, constituting an independent Hellenic languages, Hellenic branch within the Indo-European language family. It is native to Greece, Cyprus, Italy (in Calabria and Salento), southern Albania, and other regions of the Balkans, Caucasus, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the list of languages by first written accounts, longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting importance in the European canon. Greek is also the language in which many of the foundational texts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about eight phyla. Current research in phylogenetics is uncovering the relationships among phyla within larger clades like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguishe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clamp Connection
A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of basidiomycete fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types. It is used to maintain genetic variation within the hypha much like the mechanisms found in croziers (hooks) during the sexual reproduction of ascomycetes. Formation Clamp connections are formed by the terminal hypha during elongation. Before the clamp connection is formed this terminal segment contains two nuclei. Once the terminal segment is long enough it begins to form the clamp connection. At the same time, each nucleus undergoes mitotic division to produce two daughter nuclei. As the clamp continues to develop it uptakes one of the daughter (green circle) nuclei and separates it from its sister nucleus. While this is occurring t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crozier (mycology)
A crozier is an anatomical feature of many fungi in the phylum Ascomycota that forms at the base of ascus, asci and looks like a hook-topped shepherd’s staff or stylized religious crosier. Croziers resemble and function similarly to clamp connections on the dikaryotic hyphae of Basidiomycota. During initial ascus formation in Ascomycota fruitbodies, the crozier helps to maintain the dikaryotic state of both the ascus itself and of the side branch that will continue propagation of the ascogenous hyphae. The tips of developing asci on these ascogenous hyphae curl over. One haploid nucleus migrates into the curved tip while the other compatible haploid nucleus remains in the penultimate space below the hook. The ascus itself forms as a radiating spur branch at the top of the hook. Each Cell nucleus, nucleus divides, resulting in the formation of a pair of compatible nuclei, i.e. a dikaryon, in the ascus, which is now the penultimate space. Two sister nuclei remain, one in the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
