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Peach Latent Mosaic Viroid
''Peach latent mosaic viroid'' is a species of the genus ''Pelamoviroid'', which belongs to the family ''Avsunviroidae''. This family is characterized as having chloroplastic viroids with hammerhead ribozymes. Peach latent mosaic viroid is a 336-351Nucleotide, nt circular RNA which has a branched formation. This branched formation is stabilised by a pseudoknot between two kissing loops. Peach latent mosaic viroid was first described in the 1980s in Spain by a group of scientists. It is present in all peach- and nectarine, nectarine-producing areas of the world including Europe, Asia, North America and South America and the frequency of naturally occurring infection is high. Before the development of symptoms the disease is latent in peach trees for approximately 5–7 years. The symptoms of the disease include necrosis of buds, delayed shoot development, necrotic branches, premature ageing of trees, flower streaking, ripening deformations, enlarged rounded stones, circular discolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely. The first discoveries of viroids in the 1970s triggered the historically third major extension of the biosphere—to include smaller lifelike entities —after the discoveries in 1675 by Antonie van Leeuwenhoek (of the "subvisible" microorganisms) and in 1892–1898 by Dmitri Iosifovich Ivanovsky and Martinus Beijerinck (of the "submicroscopic" viruses). The unique properties of viroids have been recognized by the International Committee on Taxonomy of Viruses, in creating a new order of subviral agents. The first recognized viroid, the pathogenic agent of the potato spindle tuber disease, was discovered, initially molecularly characterized, and named by Theodor Otto Diener, plant pathologist a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelamoviroid
The ''Avsunviroidae'' are a family of viroids. There are four species in three genera (''Avsunviroid'', ''Elaviroid'' and '' Pelamoviroid''). They consist of RNA genomes between 246 and 375 nucleotides in length. They are single-stranded covalent circles and have intramolecular base pairing. All members lack a central conserved region. Replication Replication occurs in the chloroplasts of plant cells. Key features of replication include no helper virus required and no proteins are encoded for. Unlike the other family of viroids, ''Pospiviroidae'', ''Avsunviroidae'' are thought to replicate via a symmetrical rolling mechanism. It is thought the positive RNA strand acts as a template to form negative strands with the help of an enzyme thought to be RNA polymerase plus 3 II. The negative RNA strands are then cleaved by ribozyme activity and circularises. A second rolling circle mechanism forms a positive strand which is also cleaved by ribozyme activity and then ligated to become ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avsunviroidae
The ''Avsunviroidae'' are a family of viroids. There are four species in three genera (''Avsunviroid'', ''Elaviroid'' and ''Pelamoviroid''). They consist of RNA genomes between 246 and 375 nucleotides in length. They are single-stranded covalent circles and have intramolecular base pairing. All members lack a central conserved region. Replication Replication occurs in the chloroplasts of plant cells. Key features of replication include no helper virus required and no proteins are encoded for. Unlike the other family of viroids, ''Pospiviroidae'', ''Avsunviroidae'' are thought to replicate via a symmetrical rolling mechanism. It is thought the positive RNA strand acts as a template to form negative strands with the help of an enzyme thought to be RNA polymerase plus 3 II. The negative RNA strands are then cleaved by ribozyme activity and circularises. A second rolling circle mechanism forms a positive strand which is also cleaved by ribozyme activity and then ligated to become ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hammerhead Ribozyme
The hammerhead ribozyme is an RNA motif that catalyzes reversible cleavage and ligation reactions at a specific site within an RNA molecule. It is one of several catalytic RNAs (ribozymes) known to occur in nature. It serves as a model system for research on the Nucleic acid structure, structure and properties of RNA, and is used for targeted RNA cleavage experiments, some with proposed therapeutic applications. Named for the resemblance of early secondary structure diagrams to a hammerhead shark, hammerhead ribozymes were originally discovered in two classes of plant virus-like RNAs: Satellite (biology), satellite RNAs and viroids. They are also known in some classes of Retrotransposon, retrotransposons, including the Retrozyme, retrozymes. The hammerhead ribozyme motif has been ubiquitously reported in lineages across the tree of life. The self-cleavage reactions, first reported in 1986, are part of a rolling circle replication mechanism. The hammerhead sequence is sufficient fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver. Nucleotides are composed of three subunit molecules: a nucleobase, a five-carbon sugar (ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine and thymine; in RNA, uracil is used in place of thymine. Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP) and uridine triphosphate (UTP)—throughout the cell for the many cellular func ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circular RNA
Circular RNA (or circRNA) is a type of single-stranded RNA which, unlike linear RNA, forms a covalently closed continuous loop. In circular RNA, the 3' and 5' ends normally present in an RNA molecule have been joined together. This feature confers numerous properties to circular RNA, many of which have only recently been identified. Many types of circular RNA arise from otherwise protein-coding genes. Some circular RNA has been shown to code for proteins. Some types of circular RNA have also recently shown potential as gene regulators. The biological function of most circular RNA is unclear. Because circular RNA does not have 5' or 3' ends, it is resistant to exonuclease-mediated degradation and is presumably more stable than most linear RNA in cells. Circular RNA has been linked to some diseases such as cancer. RNA splicing In contrast to genes in bacteria, eukaryotic genes are split by non-coding sequences called introns. In eukaryotes, as a gene is transcribed from DNA int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoknot
__NOTOC__ A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow mosaic virus in 1982. Pseudoknots fold into knot-shaped three-dimensional conformations but are not true topological knots. Prediction and identification The structural configuration of pseudoknots does not lend itself well to bio-computational detection due to its context-sensitivity or "overlapping" nature. The base pairing in pseudoknots is not well nested; that is, base pairs occur that "overlap" one another in sequence position. This makes the presence of pseudoknots in RNA sequences more difficult to predict by the standard method of dynamic programming, which use a recursive scoring system to identify paired stems and consequently, most cannot detect non-nested base pairs. The newer method of stochastic context-free grammars su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peach
The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, non-fuzzy varieties), nectarines. The specific name ''persica'' refers to its widespread cultivation in Persia (modern-day Iran), from where it was transplanted to Europe. It belongs to the genus ''Prunus'', which includes the cherry, apricot, almond, and plum, in the rose family. The peach is classified with the almond in the subgenus '' Amygdalus'', distinguished from the other subgenera by the corrugated seed shell (endocarp). Due to their close relatedness, the kernel of a peach stone tastes remarkably similar to almond, and peach stones are often used to make a cheap version of marzipan, known as persipan. Peaches and nectarines are the same species, though they are regarded commercially as different fruits. The skin of nectarines lac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectarine
The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, non-fuzzy varieties), nectarines. The specific name ''persica'' refers to its widespread cultivation in Persia (modern-day Iran), from where it was transplanted to Europe. It belongs to the genus ''Prunus'', which includes the cherry, apricot, almond, and plum, in the rose family. The peach is classified with the almond in the subgenus '' Amygdalus'', distinguished from the other subgenera by the corrugated seed shell (endocarp). Due to their close relatedness, the kernel of a peach stone tastes remarkably similar to almond, and peach stones are often used to make a cheap version of marzipan, known as persipan. Peaches and nectarines are the same species, though they are regarded commercially as different fruits. The skin of nectarines lacks the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Necrosis
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated digestion of cell components. In contrast, apoptosis is a naturally occurring programmed and targeted cause of cellular death. While apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal. Cellular death due to necrosis does not follow the apoptotic signal transduction pathway, but rather various receptors are activated and result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space. This initiates in the surrounding tissue an inflammatory response, which attracts leukocytes and nearby phagocytes which eliminate the dead cells by phagocytosis. However, microbial damaging substances released by leukocytes would crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myzus Persicae
''Myzus persicae'', known as the green peach aphid, greenfly, or the peach-potato aphid, is a small green aphid belonging to the order Hemiptera. It is the most significant aphid pest of peach trees, causing decreased growth, shrivelling of the leaves and the death of various tissues. It also acts as a vector for the transport of plant viruses such as cucumber mosaic virus (CMV), potato virus Y (PVY) and tobacco etch virus (TEV). Potato virus Y and potato leafroll virus can be passed to members of the nightshade/potato family (Solanaceae), and various mosaic viruses to many other food crops. Originally described by Swiss entomologist Johann Heinrich Sulzer in 1776, its specific name is derived from the Latin genitive ''persicae,'' "of the peach". The syntype specimen of this species is located in the Illinois Natural History Survey Insect Collection. Life cycle Life cycle of the green peach aphid varies depending on temperature. A fully completed generation takes approximately 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viroids
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely. The first discoveries of viroids in the 1970s triggered the historically third major extension of the biosphere—to include smaller lifelike entities —after the discoveries in 1675 by Antonie van Leeuwenhoek (of the "subvisible" microorganisms) and in 1892–1898 by Dmitri Iosifovich Ivanovsky and Martinus Beijerinck (of the "submicroscopic" viruses). The unique properties of viroids have been recognized by the International Committee on Taxonomy of Viruses, in creating a new order of subviral agents. The first recognized viroid, the pathogenic agent of the potato spindle tuber disease, was discovered, initially molecularly characterized, and named by Theodor Otto Diener, plant pathologist a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
