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Hybrid Growth Disorders
Hybrid growth disorders refer to reduced growth or overgrowth in an organism that is a hybrid of two different species. In some sense, it is a type of hybrid dysgenesis ''P'' elements are transposable elements that were discovered in ''Drosophila'' as the causative agents of genetic traits called hybrid dysgenesis. The transposon is responsible for the ''P'' trait of the ''P'' element and it is found only in wi ... when the growth disorder proves deleterious, making it the opposite of heterosis or hybrid vigour. Hybrid growth disorders may be referred to as a growth dysplasia, especially when resulting in overgrowth, although this terminology may be confusing since the term dysplasia is commonly used to imply an impending cancer. However, a hybrid growth disorder is not caused by cancer. Hybrid growth disorders are exhibited among a variety organisms, including ligers, tigons, hybrid mice, and hybrid dwarf hamsters. A study on hybrid mice which investigated the possible cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid (biology)
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid Dysgenesis
''P'' elements are transposable elements that were discovered in ''Drosophila'' as the causative agents of genetic traits called hybrid dysgenesis. The transposon is responsible for the ''P'' trait of the ''P'' element and it is found only in wild flies. They are also found in many other eukaryotes. The ''P'' element encodes for an enzyme known as ''P'' transposase. Unlike laboratory-bred females, wild-type females are thought also to express an inhibitor to ''P'' transposase function, produced by the very same element. This inhibitor reduces the disruption to the genome caused by the movement of ''P'' elements, allowing fertile progeny. Evidence for this comes from crosses of laboratory females (which lack the ''P'' transposase inhibitor) with wild-type males (which have ''P'' elements). In the absence of the inhibitor, the ''P'' elements can proliferate throughout the genome, disrupting many genes and often proving lethal to progeny or rendering them sterile. ''P'' elements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterosis
Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. These effects can be due to Mendelian or non-Mendelian inheritance. Definitions In proposing the term heterosis to replace the older term heterozygosis, G.H. Shull aimed to avoid limiting the term to the effects that can be explained by heterozygosity in Mendelian inheritance. Heterosis is often discussed as the opposite of inbreeding depression, although differences in these two concepts can be seen in evolutionary considerations such as the role of genetic variation or the effects of genetic drift in small populations on these concepts. Inbreeding depression occurs when related parents have children with traits that negatively influence their fitness largely due to homozygosity. In such instances, outcrossing shoul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dysplasia
Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic scale include epithelial dysplasia and fibrous dysplasia of bone. Dysplasias on a mainly macroscopic scale include hip dysplasia (human), hip dysplasia, myelodysplastic syndrome, and multicystic dysplastic kidney. In one of the modern histopathology, histopathological senses of the term, dysplasia is sometimes differentiated from other categories of tissue change including hyperplasia, metaplasia, and neoplasia, and dysplasias are thus generally not cancerous. An exception is that the myelodysplasias include a range of benign tumor, benign, precancerous condition, precancerous, and cancerous forms. Various other dysplasias tend to be precancerous. The word's meanings thus cover a spectrum of histopathological variations. Microscopic sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liger
The liger is a hybrid offspring of a male lion (''Panthera leo'') and a female tiger (''Panthera tigris''). The liger has parents in the same genus but of different species. The liger is distinct from the similar hybrid called the tigon, and is the largest of all known extant felines. They enjoy swimming, which is a characteristic of tigers, and are very sociable like lions. Notably, ligers typically grow larger than either parent species, unlike tigons.Ligers messybeast.com Retrieved 4 September 2012. History The history of lion-tiger hybrids dates to at least the early 19th century in . In 1798, |
Tigon
A tigon (), tiglon () (portmanteau of ''tiger'' and ''lion''), or tion () is the hybrid offspring of a male tiger (''Panthera tigris'') and a female lion (''Panthera leo'').Techné v6n3 – Patenting and Transgenic Organisms: A Philosophical Exploration Scholar.lib.vt.edu. Retrieved on 17 September 2013. They exhibit visible characteristics from both parents: they can have both spots from the mother (lions carry genes for spots – lion cubs are spotted and some adults retain faint markings) and stripes from the father. Any mane that a male tigon may have will appear shorter and less noticeable than a lion's mane and is closer in type to the ruff of a male tiger. It is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterozygote
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campbell's Dwarf Hamster
Campbell's dwarf hamster (''Phodopus campbelli'') is a species of hamster in the genus ''Phodopus''. It was given its common name by Oldfield Thomas in honor of Charles William Campbell, who collected the first specimen in Mongolia on July 1, 1902. It is distinguished from the closely related Djungarian hamster as it has smaller ears and no dark fur on its Crown (anatomy), crown. Campbell's dwarf hamster typically has a narrow Primitive markings#Dorsal stripe, dorsal stripe compared to the Djungarian hamster and grey fur on the stomach. This hamster may be raised in captivity and kept as a small pet. In the wild, the breeding season for Campbell's dwarf hamster varies by location. For example, the breeding season begins towards the middle of April in Tuva and towards the end of April in Mongolia. However, in captivity, there is no fixed breeding season and they can breed frequently throughout the year. Females are usually sexually mature at two months of age and the gestation pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Djungarian Hamster
The winter white dwarf hamster (''Phodopus sungorus''), also known as the Russian dwarf hamster, Djungarian hamster, striped dwarf hamster, Siberian hamster, or Siberian dwarf hamster, is one of three species of hamster in the genus ''Phodopus''. It is ball-shaped and typically half the size of the Syrian hamster, so is called a dwarf hamster along with all ''Phodopus'' species. Features of the winter white hamster include a typically thick, dark grey dorsal stripe and furry feet. As winter approaches and the days shorten, the winter white dwarf hamster's dark fur is almost entirely replaced with white fur. In captivity, this does not usually happen as animals maintained as pets are generally housed indoors and exposed to artificial light that prevents the recognition of short winter daylengths. In the wild, they originate from the wheat fields of Kazakhstan, the meadows of Mongolia and Siberia, and the birch stands of Manchuria. Winter white dwarf hamsters are common as pets in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F1 Hybrid
An F1 hybrid (also known as filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where the term F1 crossbreed may be used. The term is sometimes written with a subscript, as F hybrid. Subsequent generations are called F, F, etc. The offspring of distinctly different parental types produce a new, uniform phenotype with a combination of characteristics from the parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal breeding, the parents often are two inbred lines. Gregor Mendel focused on patterns of inheritance and the genetic basis for variation. In his cross-pollination experiments involving two true-breeding, or homozygous, parents, Mendel found that the resulting F1 generation was heterozygous and consistent. The offspring showed a combination of the phenotypes from each parent that were genetically dominant. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
