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Zamia Staggers
Zamia staggers is a fatal nervous disease affecting cattle in areas where they browse on the leaves or fruit of cycads—in particular, those of the genus Zamia (thus the name). It is characterised by irreversible paralysis of the hind legs because of the degeneration of the spinal cord. It is caused by the toxins cycasin and macrozamin, β-glycosides (the sugars of which are glucose and primeverose, respectively) of methylazoxymethanol (MAM), and which are found in all cycad genera. Following ingestion the sugar is removed by bacterial glycosidase in the gut, with the MAM being absorbed. The metabolized toxin produces tumours of the liver, kidney, intestine and brain after a latent period which may be a year or longer. The disease has been known in Australia since the 1860s and was the subject of a Queensland Government investigation during the 1890s. See also * beta-Methylamino-L-alanine * Methyl-ONN-azoxymethanol beta-D-glucosyltransferase In enzymology, a methyl-ONN-az ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for Arecaceae, palms or ferns, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their fertilization, unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobilus, strobili), somewhat similar to conife ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zamia
''Zamia'' is a genus of cycad of the family Zamiaceae, native to North America from the United States (in Georgia and Florida) throughout the West Indies, Central America, and South America as far south as Bolivia. The genus is considered to be the most ecologically and morphologically diverse cycads, and is estimated to have originated about 68.3 million years ago. Description The genus comprises deciduous shrubs with aerial or subterranean circular stems, often superficially resembling palms. They produce spirally arranged, pinnate leaves which are pubescent, at least when young, having branched and simple, transparent and coloured hairs. The articulated leaflets lack a midrib, and are broad with subparallel dichotomous venation. Lower leaflets are not reduced to spines, though the petioles often have prickles. The emerging leaves of many ''Zamia'' species are striking, some emerging with a reddish or bronze cast ('' Z. roeslii'' being an example). ''Zamia picta'' is even more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diameter of the spinal cord ranges from in the cervical and lumbar regions to in the thoracic area. The spinal cord functions primarily in the transmission of nerve signals from the motor cortex to the body, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849–1919) and is derived from the word toxic. Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their toxicity, ranging from usually minor (such as a bee sting) to potentially fatal even at extremely low doses (such as botulinum toxin). Toxins are largely secondary metabolites, which are organic compounds that are not directly involved in an organism's growth, development, or reproduction, instead often aiding it in matters of defense. Terminology Toxins are often distinguished from other chemical agents strictly based on their biological origin. Le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycasin
Cycasin is a carcinogenic and neurotoxic glucoside found in cycads such as ''Cycas revoluta'' and ''Zamia pumila''. Symptoms of poisoning include vomiting, diarrhea, weakness, seizures, and hepatotoxicity. In metabolic conditions, cycasin is hydrolyzed into glucose and methylazoxymethanol (MAM), the latter of which dissociates into formaldehyde and diazomethane. It induces hepatotoxicity and Zamia staggers, a fatal nervous disease affecting cattle resulting from browsing on the leaves or other parts of cycads. Sources Cycasin is found in all known cycad genera and is distributed throughout the body of the plant, but with the highest concentration in the seeds. It is one of several toxins found in cycad plants, along with the neurotoxic amino acid BMAA. The origin and biological role of these toxins is unknown, as there does not appear to be a statistically significant correlation between the concentration of toxic material and the types of herbivory observed in animals consuming th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylazoxymethanol Acetate
Methylazoxymethanol acetate, MAM, is a neurotoxin which reduces DNA synthesis used in making animal models of neurological diseases including schizophrenia and epilepsy. MAM is found in cycad seeds, and causes zamia staggers. It selectively targets neuroblasts in the central nervous system. In rats, administration of MAM affects structures in the brain which are developing most quickly. It is an acetate of methylazoxymethanol. MAM animal models Schizophrenia In rat models, the specific effect of MAM on neural development depends on the gestational age of the subject. At the seventeenth gestational day (GD17), administration of MAM produces behavioral and histopathological patterns found in schizophrenia. The molecular mechanism behind this model is not fully known. Methylazoxymethanol acetate administered at GD17 reduces the thickness of the hippocampus and the thalamus. The locomotor effects of amphetamines and the spontaneous firing rate of dopaminergic neurons in the ventra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycosidase
Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cellulase), hemicellulose, and starch (amylase), in anti-bacterial defense strategies (e.g., lysozyme), in pathogenesis mechanisms (e.g., viral neuraminidases) and in normal cellular function (e.g., trimming mannosidases involved in N-linked glycoprotein biosynthesis). Together with glycosyltransferases, glycosidases form the major catalytic machinery for the synthesis and breakage of glycosidic bonds. Occurrence and importance Glycoside hydrolases are found in essentially all domains of life. In prokaryotes, they are found both as intracellular and extracellular enzymes that are largely involved in nutrient acquisition. One of the important occurrences of glycoside hydrolases in bacteria is the enzyme beta-galactosidase (LacZ), which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Government Of Queensland
The Queensland Government is the democratic administrative authority of the States and territories of Australia, Australian state of Queensland. The Government of Queensland, a parliamentary system, parliamentary constitutional monarchy was formed in 1859 as prescribed in its Constitution of Queensland, Constitution, as amended from time to time. Since the Federation of Australia in 1901, Queensland has been a States and territories of Australia, State of Australia, with the Constitution of Australia regulating the relationships between all state and territory governments and the Australian Government. Under the Australian Constitution, all states and territories (including Queensland) Section 51 of the Constitution of Australia, ceded powers relating to certain matters to the federal government. The government is influenced by the Westminster system and Federalism in Australia, Australia's federal system of government. The Governor of Queensland, as the representative of Charles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-Methylamino-L-alanine
β-Methylamino--alanine, or BMAA, is a non-proteinogenic amino acid produced by cyanobacteria. BMAA is a neurotoxin and its potential role in various neurodegenerative disorders is the subject of scientific research. Structure and properties BMAA is a derivative of the amino acid alanine with a methylamino group on the side chain. This non-proteinogenic amino acid is classified as a polar base. Sources and detection BMAA is produced by cyanobacteria in marine, freshwater, and terrestrial environments. In cultured non-nitrogen-fixing cyanobacteria, BMAA production increases in a nitrogen-depleted medium. The biosynthetic pathway in cyanobacteria is unknown, but involvement of BMAA and its structural analog 2,4-diaminobutanoic acid (2,4-DAB) in envioronmental iron scavenging has been hypothesized. BMAA has been found in aquatic organisms and in plants with cyanobacterial symbionts such as certain lichens, the floating fern ''Azolla'', the leaf petioles of the tropical fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl-ONN-azoxymethanol Beta-D-glucosyltransferase
In enzymology, a methyl-ONN-azoxymethanol beta-D-glucosyltransferase () is an enzyme that catalyzes the chemical reaction :UDP-glucose + methyl-ONN-azoxymethanol \rightleftharpoons UDP + cycasin Thus, the two substrates of this enzyme are UDP-glucose and methyl-ONN-azoxymethanol, whereas its two products are UDP and cycasin. This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ... of this enzyme class is UDP-glucose:methyl-ONN-azoxymethanol beta-D-glucosyltransferase. Other names in common use include cycasin synthase, uridine diphosphoglucose-methylazoxymethanol glucosyltransferase, and UDP-glucose-methylazoxymethanol glucosyltransferase. References * EC 2.4. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bovine Diseases
Bovines (subfamily Bovinae) comprise a diverse group of 10 genera of medium to large-sized ungulates, including cattle, bison, African buffalo, water buffalos, and the four-horned and spiral-horned antelopes. The evolutionary relationship between the members of the group is still debated, and their classification into loose tribes rather than formal subgroups reflects this uncertainty. General characteristics include cloven hooves and usually at least one of the sexes of a species having true horns. The largest extant bovine is the gaur. In many countries, bovid milk and meat is used as food by humans. Cattle are kept as livestock almost everywhere except in parts of India and Nepal, where they are considered sacred by most Hindus. Bovids are used as draft animals and as riding animals. Small breeds of domestic bovid, such as the Miniature Zebu, are kept as pets. Bovid leather is durable and flexible and is used to produce a wide range of goods including clothing and bags. Sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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