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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Neurofibromatosis - Neurotransmitter
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Nesidioblastosis
A condition in which there is a developmental abnormality of the pancreatic ducts and islet cells that results in hypoglycaemia. This condition may be precipitated by leucine.
Nested deletion
A deleted region of a nucleic acid within a second larger deletion of the same molecule. the smaller deletion is thus nested within the larger deletion.
Nested fragments
A series of nucleic acid fragments that differ in length from each other by one or more nucleotides.
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Nested gene
A single gene that produces two or more nested products by modulating the end point of protein synthesis.This may occur by leaky readthrough of a termination codon, cotragnslational frameshifting, alternative splicing or by use of alternative polyadenylation sites.
Nested PCR
A technique that involves use of a second set of primers internal to the first pair in a PCR. This increases the sensitivity and specificity by minimising the amplification of spurious products.
Nets cape Navigator
A popular Internet browser.
Network topology
The physical pattern of networks, computers and terminals.
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Neu oncogene
An oncogene isolated from rat cells by transfection into 3T3 cells that has a sequence homologous to the erb-B oncogene. neu is believed to be activated by a point mutation of the proto-oncogene.
Neural cell adhesion molecule (N-CAM)
A cell adhesion molecule expressed by many cell types including nerve cells that mediates Ca2+ -independent cell-cell attachment in vertebrates.
Neural net
An interconnected assembly of simple processing elements, units or nodes, the functionality of which is roughly based on the animal brain. Neural nets are used in bioinformatics to map data and make predictions, such as identifying novel members of a protein family from their sequence data alone.
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Neural tube
Tube of endoderm that forms the brain and spinal cord in a vertebrate embryo.
Neural tube defect
A birth defect caused by abnormal development of the neural tube, a structure that gives rise to the central nervous system. Neural tube defects include anencephaly and spina bifida.
Neuraminidase
A glycoprotein found in the form of a spike on the outside of the influenza virus envelope.The enzyme breaks down an inhibitor of the influenza virus haemagglutinin (HA) protein.
Neurite
A long process that grows from a nerve cell in culture. The term does not specify whether the process is an axon or a dendrite.
Neuritis
Inflammation of the nerves.
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Neuroblastomas
Rare tumours of nerve cells that occur in infants and children that form part of APUD (amine precursor uptake and decarboxylation) tumours. These are highly malignant tumours, 40 per cent of which are in the adrenal medulla, while 60 per cent are extra-adrenal. The plasma catecholamines are very high. Some neuroblastomas however, secrete dopamine.
Neurodegenerative diseases
Diseases that result from the degeneration or deterioration of neurons such as Alzheimer's disease and Parkinson's disease.
Neurofibromatosis
An inherited progressive disorder characterised by development of tumours on peripheral nerves with loss of hearing and vision, epilepsy, bone deformities, learning disabilities and cancer.
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Neurofilament
A type of intermediate filament present in nerve cells.
Neuromuscular junction
A specialised chemical synapse between an axon terminal of a motor neuron and skeletal muscle cell.
Neuron
A cell of nervous tissue that is specialised for the transmission of a nerve impulse.
Neuropathy
Nerve damage or disease.
Neuropeptide
A peptide secreted by neurons as a signal at synapses or elsewhere.
Neurospora
A genus of mold used in genetic experiments because it exists in the haploid state and it forms the ascus, a structure from which single celled spores can be isolated.Neurospora was used to demonstrate that proteins are encoded by genes.
Neurotoxic
Toxic or damaging to nervous tissue such as the brain and peripheral nerves.
Neurotransmitter
A low molecular weight nitrogen-containing compound secreted from a neuron terminal and bound by a specific receptor in the next neuron that serves to transmit a nerve impulse.
Neutral mutation
A mutation that alters the nucleotide sequence of a gene but has negligible or no effect on the fitness of the organism.
Neutral substitutions
Changes of amino acids in a protein that do not affect activity.
Neutral sulphur
Incompletely oxidised sulphur in urine such as that found in cystine and taurine.
Neutral theory
The theory that much of evolution is primarily due to random drift of neutral mutations.
Neutron
Uncharged subatomic particle present in the atomic nucleus.
Neutron scattering
A technique used to enhance X-ray crystallographic images because neutrons generate strong diffraction patterns from small atoms such as hydrogen.
Neutrophil
A white blood cell specialised for phagocytosis and which invades tissues that are infected or inflamed.
New Chemical Entities (NCEs)
Compounds identified as potential drugs that are taken up for clinical trials to determine their suitability.
NF-kB (nuclear factor-kappa B)
A prototype of the eukaryotic redox-sensitive nuclear transcription factor. It is a dimeric Rel protein that contains two subunits-p50 and p65 (Rel A). NF-kB is activated by a variety of stimuli including cytokines, mitogen-activated protein kinase (MAPK) signalling, reactive oxygen species, carcinogens, UV radiation, phorbol esters, asbestos, alcohol, and benzo[a] pyrene. The NF-kB activation complex is located in the cytoplasm bound to l-kB (inhibitor kB) in its inactive form.
Activation of NF-kB requires degradation of l-kB followed by nuclear translocation of the active NF-kB, which binds to specific DNA sequences termed kB elements and regulates the transcription of genes mediating inflammation, carcinogenesis, and anti-apoptotic reactions. The net effect of gene activation by NF-kB is stimulation of cell proliferation and inhibition of apoptosis. Overexpression of NF-kB occurs in many cancers.
NHGRI
See National Human Genome Research Institute.
Niacin (nicotinic acid)
A water-soluble vitamin and member of the B-complex vitamins. It is a constituent of the coenzymes-NAD+ and NADP+ which function as electron carriers in redox reactions and play a vital role in glycolysis, oxidative phosphorylation and many synthetic and catabolic processes. Niacin deficiency causes pellagra. Niacin lowers VLDL and LDL and elevates HDL cholesterol. It is used as a hypolipidaemic drug and for reducing the recurrence of ischaemic heart disease and mortality.
Niacin
Niacytin
The niacin in maize which is in the bound, unavailable form.
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