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Fusome
The fusome is a membranous structure found in the developing germ cell cysts of many insect orders.Telfer, W. H. 1975. Development and physiology of the oocyte-nurse cell syncytium. Advances in insect physiology 11:223-319. DOI: 10.1016/S0065-2806(08)60164-2Snapp, E. L., T. Iida, D. Frescas, J. Lippincott-Schwartz, and M. A. Lilly. (2004). The fusome mediates intercellular endoplasmic reticulum connectivity in ''Drosophila'' ovarian cysts. Mol Biol Cell 15: 4512-4521. doi/10.1091/mbc.E04 – 06 – 0475.Greenbaum, M. P., T. Iwarmori, G. M. Buchold, and M. M. Matzuk. (2011). Germ Cell Intercellular Bridges. Cold Spring Harb Perspect Biol 3:a005850 doi: 10.1101/cshperspect.a005850 Initial description of the fusome occurred in the 19th century and since then the fusome has been extensively studied in ''Drosophila melanogaster'' male and female germline development. This structure has roles in maintaining germline cysts, coordinating the number of Mitosis, mitotic divisions prior to me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovariole Niche
An ovariole is a tubular component of the insect ovary, and the basic unit of egg production. Each ovariole is composed of a germarium (the germline Stem-cell niche, stem cell niche) at the anterior tip, a set of developing Oocyte, oocytes contained within Follicle (anatomy), follicles, and a posterior connection to a common oviduct. While most insects have two ovaries, the number of ovarioles within each ovary varies across insect species. This number may also be variable across individuals within a species, or between the left and right ovaries within an individual. Types Ovarioles are often classified into one of several types by the presence and position of Nurse cell, nurse cells. These specialized cells provide nutrition and molecules important for embryonic patterning to the developing oocyte. Ovarioles that lack nurse cells are referred to as ''panoistic'' and ovarioles with nurse cells are referred to as ''meroistic''. Meroistic ovarioles are further classified accordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrion
A mitochondrion () is an organelle found in the cell (biology), cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'', meaning a thread-like granule, was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase popularized by Philip Siekevitz in a 1957 ''Scientific American'' article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). The multicellular animal ''Henneguya zschokkei, Henneguya salminicola'' is known to have retained mitochondrion-related organelles despite a complete loss of their mitochondrial genome. A large number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatozoon
A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is the male gamete that Fertilization, joins with an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, that normally develops into an embryo.) Sperm cells contribute approximately half of the nuclear gene, genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA). In mammals, the sex of the offspring is determined by the sperm cell: a spermatozoon bearing an X chromosome will lead to a female (XX) offspring, while one bearing a Y chromosome will lead to a male (XY) offspring. Sperm cells were first observed in Antonie van Leeuwenhoek's laboratory in 1677. Mammalian spermatozoa Humans The sperm cell of ''Homo sapiens'' is the small Gamete, reproductive cell produced by m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemistry, Biochemical events lead to characteristic cell changes (Morphology (biology), morphology) and death. These changes include Bleb (cell biology), blebbing, Plasmolysis, cell shrinkage, Karyorrhexis, nuclear fragmentation, Pyknosis, chromatin condensation, Apoptotic DNA fragmentation, DNA fragmentation, and mRNA decay. The average adult human loses 50 to 70 1,000,000,000, billion cells each day due to apoptosis. For the average human child between 8 and 14 years old, each day the approximate loss is 20 to 30 billion cells. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Damage
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is constantly modified in cells, by internal metabolic by-products, and by external ionizing radiation, ultraviolet light, and medicines, resulting in spontaneous DNA damage involving tens of thousands of individual molecular lesions per cell per day. DNA modifications can also be programmed. Molecular lesions can cause structural damage to the DNA molecule, and can alter or eliminate the cell's ability for transcription and gene expression. Other lesions may induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells following mitosis. Consequently, DNA repair as part of the DNA damage response (DDR) is constantly active. When normal repair processes fail, including apoptosis, irreparable DNA damage may occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nurse Cell
In general biology or reproductive physiology, a nurse cell is a cell which provides food, helps other cells and provides stability to neighboring cells. The term nurse cell is used in several unrelated ways in different scientific fields. Human physiology Nurse cells are specialized macrophages residing in the bone marrow that assist in the development of red blood cells. They absorb the nuclei of immature red blood cells and may provide growth factors to help the red blood cells mature. In the bone marrow, immature red blood cells (erythroblasts) can be seen grouped in a cluster around a nurse cell. The epithelial cell found in the cortex of the thymus is also called a "nurse cell." These cells produce Thymic hormones that cause T lymphocytes to mature and differentiate. Parasitology In parasitology, a nurse cell is an infected cell in the disease trichinosis discovered by Dickson Despommier. A trichinella larva enters a cell and develops there, probably as a way of concealing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centriole
In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers ( Pinophyta), flowering plants ( angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and ''Ginkgo''. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome. Centrioles are typically made up of nine sets of short microtubule triplets, arranged in a cylinder. Deviations from this structure include crabs and ''Drosophila melanogaster'' embryos, with nine doublets, and '' Caenorhabditis elegans'' sperm cells and early embryos, with nine singlets. Additional proteins include centrin, cenexin and tektin. The main function of centrioles is to produce cilia during interphase and the aster and the spindle durin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrosome
In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') (archaically cytocentre) is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell. It is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species. Centrosomes are composed of two centrioles arranged at right angles to each other, and surrounded by a dense, highly structured mass of protein termed the pericentriolar material (PCM). The PCM contains proteins responsible for microtubule nucleation and anchoring — including γ-tubulin, pericentrin and ninein. In general, each centriole of the centrosome is based on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G2 Phase
G2 phase, Gap 2 phase, or Growth 2 phase, is the third subphase of interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell’s DNA is replicated. G2 phase ends with the onset of prophase, the first phase of mitosis in which the cell’s chromatin condenses into chromosomes. G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. Curiously, G2 phase is not a necessary part of the cell cycle, as some cell types (particularly young ''Xenopus'' embryos and some cancers)) proceed directly from DNA replication to mitosis. Though much is known about the genetic network which regulates G2 phase and subsequent entry into mitosis, there is still much to be discovered concerning its significance and regulation, particularly in regards to cancer. One hypothesis is that the growth in G2 phase is regulated as a method of cell size control. Fission yeast (''Sch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SCF Complex
Skp, Cullin, F-box containing complex (or SCF complex) is a multi-protein E3 ubiquitin ligase complex that catalyzes the ubiquitination of proteins destined for 26S proteasomal degradation. Along with the anaphase-promoting complex, SCF has important roles in the ubiquitination of proteins involved in the cell cycle. The SCF complex also marks various other cellular proteins for destruction. Core components SCF contains a variable F-box protein and three core subunits: * F-box protein (FBP) – FBP contributes to the substrate specificity of the SCF complex by first aggregating to target proteins independently of the complex. Each FBP (e.g. Skp2) may recognize several different substrates in a manner that is dependent on post-translational modifications such as phosphorylation or glycosylation. FBP then binds to Skp1 of the SCF complex using an F-box motif, bringing the target protein into proximity with the functional E2 ubiquitin-conjugating enzyme. FBP is also essential in re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gertrud Schüpbach
Trudi Schüpbach (born Zurich, Switzerland, February 3, 1950; full name Gertrud M. Schüpbach; published name Trudi Schüpbach) is a Swiss- American molecular biologist. She is an Emeritus Professor of Molecular Biology at Princeton University, where her laboratory studies molecular and genetic mechanisms in fruit fly (''Drosophila melanogaster'') oogenesis. Research Schüpbach's research focuses on signaling pathways that are involved in pattern formation during embryonic development. Using the fruit fly (''Drosophila melanogaster'') as a model system, she revealed molecular mechanisms underlying the determination of the major axis of the embryo. Performing genetic screens, she identified mutants that result in female sterility of which many affect embryonic body patterning. By that, she contributed to the understanding of maternal factors that are deposited into the forming egg during oogenesis and that are conferred into spatial information within the developing embryo to de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin E
Cyclin E is a member of the cyclin family. Cyclin E binds to G1 phase Cdk2, which is required for the transition from G1 to S phase of the cell cycle that determines initiation of DNA duplication. The Cyclin E/CDK2 complex phosphorylates p27Kip1 (an inhibitor of Cyclin D), tagging it for degradation, thus promoting expression of Cyclin A, allowing progression to S phase. Functions of Cyclin E Like all cyclin family members, cyclin E forms complexes with cyclin-dependent kinases. In particular, Cyclin E binds with CDK2. Cyclin E/CDK2 regulates multiple cellular processes by phosphorylating numerous downstream proteins. Cyclin E/CDK2 plays a critical role in the G1 phase and in the G1-S phase transition In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta .... Cyclin E/CDK2 phosphor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
