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Labrador Retriever Coat Colour Genetics
The genetic basis of coat colour in the Labrador Retriever has been found to depend on several distinct genes. The interplay among these genes is used as an example of epistasis. Background Labrador Retrievers are a popular dog breed in many countries. There are three recognised colours, black, chocolate, and yellow,Carol Coode, ''Labrador Retrievers Today'', Howell Book House: New York, 1993. that result from the interplay among genes that direct production and expression of two pigments, eumelanin (brown or black pigment) and pheomelanin (yellow to red pigment), in the fur and skin of the dog. The recognized colours are due to two genes, while a third gene affects the range of colouration observed within the yellow Labrador. These individual genes do not act independently of each other, and their interaction in affecting the trait of coat colour is used by biology textbooks to demonstrate the genetic principle of epistasis, where multiple genes react synergistically to affec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutations
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication (translesion synthesis). Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Golden Retrievers
The Golden Retriever is a Scottish breed of retriever dog of medium size. It is characterised by a gentle and affectionate nature and a striking golden coat. It is commonly kept as a pet and is among the most frequently registered breeds in several Western countries. It is a frequent competitor in dog shows and obedience trials; it is also used as a gundog, and may be trained for use as a guide dog. The breed was created by Sir Dudley Marjoribanks at his Scottish estate Guisachan in the late nineteenth century. He cross-bred Flat-coated Retrievers with Tweed Water Spaniels, with some further infusions of Red Setter, Labrador Retriever and Bloodhound. The breed was recognised by the Kennel Club in 1913, and during the interwar period spread to many parts of the world. History The Golden Retriever was developed in Scotland in the nineteenth century by Sir Dudley Marjoribanks (later to become Baron Tweedmouth) from Flat-coated Retrievers judiciously crossed with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixation (population Genetics)
In population genetics, fixation is the change in a gene pool from a situation where there exists at least two variants of a particular gene (allele) in a given population to a situation where only one of the alleles remains. In the absence of mutation or heterozygote advantage, any allele must eventually be lost completely from the population or fixed (permanently established at 100% frequency in the population). Whether a gene will ultimately be lost or fixed is dependent on selection coefficients and chance fluctuations in allelic proportions. Fixation can refer to a gene in general or particular nucleotide position in the DNA chain (locus). In the process of substitution, a previously non-existent allele arises by mutation and undergoes fixation by spreading through the population by random genetic drift or positive selection. Once the frequency of the allele is at 100%, i.e. being the only gene variant present in any member, it is said to be "fixed" in the population. Simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DEFB103A
Beta-defensin 103 is a protein that in humans is encoded by the ''DEFB103A'' gene. Function Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Members of the defensin family are highly similar in protein sequence. This gene encodes defensin, beta 103B, which has broad spectrum antimicrobial activity and may play an important role in innate epithelial defense. In dogs, the product of the same genetic locus, β-Defensin 103, also plays a role in pigmentation, being an agonist of the melanocortin 1 receptor The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones .... References Further reading * * * * * * * * * * * * * * * * * * Defensins {{gene-8-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Defensin
Beta defensins are a family of vertebrate defensins. The beta defensins are antimicrobial peptides implicated in the resistance of epithelial surfaces to microbial colonization. Defensins are 2-6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses, containing three pairs of intramolecular disulfide bonds. On the basis of their size and pattern of disulfide bonding, mammalian defensins are classified into alpha, beta and theta categories. Every mammalian species explored thus far has beta-defensins. In cows, as many as 13 beta-defensins exist in neutrophils. However, in other species, beta-defensins are more often produced by epithelial cells lining various organs (e.g. the epidermis, bronchial tree and genitourinary tract. Human, rabbit and guinea-pig beta-defensins, as well as human beta-defensin-2 (hBD2), induce the activation and degranulation of mast cells, resulting in the release of histamine and pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kermode Bear
The Kermode bear, sometimes called the spirit bear (''Ursus americanus kermodei''), is a subspecies of the American black bear and lives in the Central and North Coast regions of British Columbia, Canada. It is the official provincial mammal of British Columbia and symbol of Terrace, British Columbia. While most Kermode bears are black, between 100 and 500 fully white individuals exist. The white variant is known as spirit bear, and is most common on three islands in British Columbia ( Gribbell, Princess Royal, and Roderick), where they make up 10–20% of the Kermode population. Spirit bears hold a prominent place in the oral traditions of the indigenous peoples of the area. They have also been featured in a National Geographic documentary. Description The Kermode bear was named after Frank Kermode, former director of the Royal B.C. Museum, who researched the subspecies and was a colleague of William Hornaday, the zoologist who described it. Today, the name ''Kermode' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocortin
The melanocortins are a family of neuropeptide hormones which are the ligands of the melanocortin receptorsEricson, M.D., et al., ''Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016.'' Biochim Biophys Acta Mol Basis Dis, 2017. 1863(10 Pt A): p. 2414-2435. The melanocortin system consists of melanocortin receptors, ligands, and accessory proteins. The genes of the melanocortin system are found in chordates. Melanocortins were originally named so because their earliest known function was in melanogenesis. It is now known that the melanocortin system regulates diverse functions throughout the body, including inflammatory response, fibrosis, melanogenesis, steroidogenesis, energy homeostasis, sexual function, and exocrine gland function. There are four endogenous melanocortin agonists which are derived from post-transcriptional processing of the precursor molecule proopiomelanocortin (POMC) (Figure 1). They are Adrenocorticotropic hormone (ACTH), a-mel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afra 005
Saint Afra (died 304) was martyred during the Diocletian persecution. Along with Saint Ulrich, she is a patron saint of Augsburg. Her feast day is August 7. Afra was dedicated to the service of the goddess, Venus, by her mother, Hilaria. Through his teachings, Bishop Narcissus converted Afra and her family to Christianity. When it was learned that Afra was a Christian, she was brought before Diocletian and ordered to sacrifice to the pagan gods. She refused, and was condemned to death by fire. Biography Although many different accounts of her life exist, the most widely known is ''The Acts of St. Afra'', which dates from the Carolingian period (8th century AD). In the opinion of most critics this is compilation of two different accounts, the story of the conversion of St. Afra, and the story of her martyrdom. The former is of later origin, and is merely a legendary narrative of Carolingian times, drawn up with the intention of connecting with St. Afra the organization of the ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genotypes
The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a specific gene depends on the number of copies of each chromosome found in that species, also referred to as ploidy. In diploid species like humans, two full sets of chromosomes are present, meaning each individual has two alleles for any given gene. If both alleles are the same, the genotype is referred to as homozygous. If the alleles are different, the genotype is referred to as heterozygous. Genotype contributes to phenotype, the observable traits and characteristics in an individual or organism. The degree to which genotype affects phenotype depends on the trait. For example, the petal color in a pea plant is exclusively determined by genotype. The petals can be purple or white depending on the alleles present in the pea plant. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alleles
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chromosomal or genomic location of a gene or any other genetic element is called a locus (plural: loci) and alternative DNA sequences at a locus are called alleles." The simplest alleles are single nucleotide polymorphisms (SNP). but they can also be insertions and deletions of up to several thousand base pairs. Popular definitions of 'allele' typically refer only to different alleles within genes. For example, the ABO blood grouping is controlled by the ABO gene, which has six common alleles (variants). In population genetics, nearly every living human's phenotype for the ABO gene is some combination of just these six alleles. Most alleles observed result in little or no change in the function of the gene product it codes for. However, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominant Trait
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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