Infection of a host by a parasite or the level of infection by the parasite, depending upon context.
parasympathetic nervous system
One of the two divisions of the vertebrate autonomic nervous sytem. Parasympathetic nerves emerge cranially as pre-ganglionic fibres from oculomotor, facial, glossopharyngeal and ...
(= parathyrin; parathyroid hormone)
A peptide hormone of 84 amino acids (9402 D). Stimulates osteoclasts to increase blood calcium levels, the opposite effect to calcitonin. ...
In immune network theory, an idiotope; an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the ...
Lying along an axis - commonest use is in reference to paraxial mesoderm, the mesoderm that forms somites as opposed to the axial mesoderm that forms notochord.
Polypeptide (33 residues) from toxin gland of Pardachirus marmoratus that forms an eight-subunit voltage-dependent pore that will induce neurotransmitter release.
Type of unspecialised cell making up the ground tissue of plants. The cells are large and usually highly vacuolated, with thin, unlignified walls. They are often photosynthetic, ...
Administration of a substance to an animal by any route other than the alimentary canal.
Structure shaped rather like a parenthesis "(", found on either side of pores in the septum of a basidiomycete fungus. More logically called septal pore caps.
Microscope objectives that are mounted in such a way that changing objectives does not put the specimen out of focus are parfocal.
Gene found to be mutated in unusual form of Parkinsonism (autosomal recessive juvenile parkinsonism). Located on long arm of Chromosome 6. Gene is large (500 kb), very active ...
(= paralysis agitans)
Disease (Parkinson\'s disease) characteried by tremor and associated with the underproduction of L-DOPA (dihydroxyphenylalanine) by dopaminergic neurons and ...
In ciliates the cilia in the region of the mouth may be fused into a paroral membrane.
See poly(ADP-ribose) polymerase.
Fruit formation without fertilization. Occurs spontaneously in some plants, eg. banana, and in other plants can be induced by application of auxin. Results in seedless fruits.
Development of an ovum without fusion of its nucleus with a male pronucleus to form a zygote.
Agonist for a receptor population that is unable to produce a maximal response even if all the receptors are occupied.
Equilibrium constant for the partitioning of a molecule between hydrophobic (oil) and hydrophilic (water) phases. A measure of the affinity of the molecule for hydrophobic ...
Calcium binding proteins (12 kD), found in teleost and amphibian muscle, with sequence homology to calmodulin but only two EF-hand calcium binding sites.
Class II viruses. The genome of these simple viruses is single stranded DNA and they have an icosahedral nucleocapsid. The autonomous parvoviruses have a negative strand DNA ...
(1) See periodic acid-Schiff reaction.
(2) p-amino-salicylic acid.
(1) See periodic acid-Schiff reaction.
(2) p-amino-salicylic acid.
Genes essential for the biogenesis and proliferation of peroxisomes in yeast ( S. cerevisiae ). PAS1 codes for a rather hydrophilic 117 kD protein with two ATP binding sites and ...
Proteins of unknown function bound, on the cytoplasmic face, to the sodium-potassium ATPase. Two pasins have been identified, pasin 1 (77 kD) and pasin 2 (73 kD). The name is ...
Term that derives originally from maintenance of, for example, a parasite by serially infecting host animals, passaging the parasite each time. Subsequently also used to describe ...
Immunity acquired by the transfer from another animal of antibody or sensitised lymphocytes. Passive transfer of antibody from mother to offspring is important for immune ...
The movement of a substance, usually across a plasma membrane, by a mechanism that does not require metabolic energy. See active transport, transport protein, facilitated ...
Decrease in the rate of carbohydrate breakdown that occurs in yeast and other cells when switched from anaerobic to aerobic conditions. Results from a relatively slow flux of ...
(= trisomy 13)
Set of congenital defects in man caused by presence of an extra Chromosome 13.
A specialized and powerful variant of voltage clamp method, in which a patch electrode of relatively large tip diameter (5 m m) is pressed tightly against the plasma membrane ...
Passive process in which integral membrane components become clustered following cross-linking by an external or internal polyvalent ligand. See capping.
A sign or symptom that is diagnostic of a disease.
One of the classic problems in developmental biology is the way in which complex patterns are formed from an apparently uniform field of cells. Various hypotheses have been put ...
Term used to describe the margination of leucocytes on the endothelium near a site of damage.
Mutant of Paramecium that, like the chess-piece, can only move forward and is unable to reverse to escape noxious stimuli. Defect is apparently in the voltage-sensitive calcium ...
Mouse genes that contain a DNA-binding domain similar to one in the paired genes of Drosophila. 8 Pax genes have been identified, and most of them are expressed in the nervous ...
Cytoskeletal protein (68 kD) that localizes, like talin, to focal adhesions, to dense plaques in smooth muscle, and to the myotendonous and neuromuscular junctions of ...
(= peripheral blood mononuclear cells)
A mixture of monocytes and lymphocytes; blood leucocytes from which granulocytes have been separated and removed.
See platelet basic protein.
A rat phaeochromocytoma cell line from adrenal medulla. Widely used in the study of stimulus-secretion coupling, and because it differentiates to resemble sympathetic ...
(= proliferating cell nuclear antigen)
Commonly used marker for proliferating cells, a 35 kD protein that associates as a trimer, and as a trimer interacts with DNA polymerases ...
See polymerase chain reaction.
(= in situ hybridization)
New technique for detection of very rare mRNA or viral transcripts in a tissue. Tissue sections are subjected to PCR, ...
(= platelet-derived endothelial cell growth factor)
Cytokine (471 residues) produced by platelets, fibroblasts and smooth muscle cells. Stimulates endothelial proliferation ...
Any enzyme (in EC 3.1 class) that catalyses the hydrolysis of one of the two ester linkages in a phosphodiester. PDE-I (EC 126.96.36.199) catalyses removal of ...
See platelet-derived growth factor.
Domains found in various intracellular signalling proteins associated with the plasma membrane; named for the postsynaptic density, disc-large, ZO-1 proteins in which they were ...
(= phosphoprotein enriched in astrocytes, 15 kD)
PEA-15 is an acidic serine-phosphorylated protein highly expressed in the CNS, where it can play a protective role against ...
Lectin from Arachis hypogaea that binds to glycoproteins containing b -D-gal (1-3) D-galNAc in membranes; used to investigate differential adhesiveness in developing systems.
A bivalve mollusc. The adductor muscle, a catch muscle, has been a favourite with muscle physiologists and biochemists as well as with gourmets.
Class of plant cell wall polysaccharide, soluble in hot aqueous solutions of chelating agents or in hot dilute acid. Includes polysaccharides rich in galacturonic acid, ...
See polyethylene glycol.
The 18 residue N-terminal leader sequence of pelB is commonly used in various vector constructs. The gene from which it comes, pelB, codes for pectin lyase B, one of the many ...
Drosophila protein kinase that is involved in the activation of dorsal (NF k B homologue).
The outer covering of a protozoan: the plasma membrane plus underlying reinforcing structures, for example the membrane-bounded spaces (alveoli) just below the plasma membrane ...
(= polymorphic epithelial mucin)
A group of dermatological diseases characterized by the production of bullae (blisters).
The proportion of individuals with a specific genotype who express that character in the phenotype.
(= dimethyl cysteine)
Product of acid hydrolysis of penicillin that chelates heavy metals (lead, copper, mercury) and assists in their excretion in cases of poisoning. Also ...
Probably the best known of the antibiotics, derived from the mould Penicillium notatum. It blocks the cross-linking reaction in peptidoglycan synthesis, and therefore destroys ...
An anticonvulsant and anaesthetic, usually used as the sodium or calcium salt.
Glycan that, when hydrolyzed, yields only pentoses.
pentose phosphate pathway
(= pentose shunt; hexose monophosphate pathway; phosphogluconate oxidative pathway)
Alternative metabolic route to Embden-Meyerhof pathway for breakdown of glucose. Diverges ...
Sugars (monosaccharide) with five carbon atoms. Include ribose and deoxyribose of nucleic acids, and many others such as the aldoses arabinose and xylose, and the ketoses ...
Family of proteins that share a discoid arrangement of five non-covalently linked subunits. Includes CRP and serum amyloid P.
Enzyme responsible for the primary fixation of CO2 in C4 plants. Carboxylates PEP (phosphoenolpyruvate) to give oxaloacetate. Also important in crassulacean acid metabolism, ...
Acid protease (EC 188.8.131.52) from stomach of vertebrates. Cleaves preferentially between two hydrophobic amino acids (eg. F-L, F-Y,), and will attack most proteins except ...
The inactive precursor (42.5 kD) of pepsin.
Peptide from Streptomyces spp. that inhibits pepsin and other aspartic proteases, for example cathepsin D and renin.
The amide linkage between the carboxyl group of one amino acid and the amino group of another. The linkage does not allow free rotation and can occur in cis or trans ...
Proteases will produce fragments of a characteristic size from a protein, and this can be used as a test for the identity or otherwise of two similar-sized proteins. It is ...
peptide nucleic acid
Synthetic nucleic acid mimic, in which the sugar-phosphate backbone is replaced by a peptide-like polyamide. Instead of 5&’ and 3&’ ends, PNAs have N and C termini. Their ...
Cross-linked polysaccharide-peptide complex of indefinite size found in the inner cell wall of all bacteria (50% of the wall in Gram negative, 10% in Gram positive). ...
(EC 184.108.40.206) Integral enzymic activity of the large subunit of a ribosome, catalysing the formation of a peptide bond between the carboxy-terminus of the nascent chain and the ...
EC 220.127.116.11 Enzyme responsible for formation of protein-bound citrulline, a major amino acid in the inner root sheath and medulla of the hair follicle. Substrate is ...
Perforins 1 and 2 form tubular transmembrane complexes (16nm diameter) at the sites of target cell lysis by NK cells and cytotoxic T-cells.
(= theta toxin; q-toxin)
Cholesterol binding toxin from Clostridium perfringens. Shares with other thiol-activated haemolysins a highly conserved sequence (ECTGLAWEWWR) near ...
Protein originally suggested to initiate myelin deposition in peripheral nerves. Two isoforms exist coded by a single gene. L-periaxin (147 kD) is localized to plasma membrane ...
Membrane derived from the plasma membrane of a plant cell and that surrounds the nitrogen-fixing bacteroids in legume root nodules. Has a high lipid content and may regulate the ...
pericanicular dense bodies
Electron-dense membrane-bounded cytoplasmic organelles found near the canaliculi in liver cells: lysosomes.
That part of a fruit that is produced by thickening of the ovary wall. Composed of three layers, epicarp (skin), mesocarp (often fleshy) and endocarp (membranous or stony in the ...
Chromosomal inversion in which the region that is inverted includes the kinetochore.
Conserved protein (200-220 kD) of the pericentriolar region involved in organization of microtubules during meiosis and mitosis; concentration highest at metaphase, lowest at ...
Rather amorphous region of electron-dense material surrounding the centriole in animal cells: the major microtubule organizing centre of the cell.
Cell of the perichondrium, the fibrous connective tissue surrounding cartilage.
Cell associated with the walls of small blood vessels: not a smooth muscle cell, nor an endothelial cell.
The outer cork layer of a plant that replaces the epidermis of primary tissues. Cells have their walls impregnated with cutin and suberin.
Cell body surrounding nucleus of a neuron - does not include axonal and dendritic processes.
Gap 10-40nm wide separating the two membranes of the nuclear envelope.
Drosophila gene regulating circadian rhythm. Expressed in CNS, Malpighian tubules, and a number of other tissues. Per contains a PAS structural domain, a nuclear localization ...
periodic acid-Schiff reaction
A method for staining carbohydrates: adjacent hydroxyl groups are oxidized to form aldehydes by periodic acid (HIO4 ) and these aldehyde groups react with Schiff\'s reagent ...
Adjective describing the region around the teeth ie. gums and gingival crevice. Periodontal disease is a common consequence of inadequate phagocyte function.
peripheral membrane protein
Membrane proteins that are bound to the surface of the membrane and not integrated into the hydrophobic region. Usually soluble and were originally thought to bind to integral ...
(1) Type III intermediate filament protein (57-58 kD) co-expressed with neurofilament triplet proteins.
(2) Photoreceptor-specific glycoprotein found on the rim region of rod ...
Genus of insects that includes P. americana, the American cockroach, a favourite experimental animal.
periplasmic binding proteins
Transport proteins located within the periplasmic space. Some act as receptors for bacterial chemotaxis, interacting with MCPs. Their mode of action is unclear.
Structureless region between the plasma membrane and the cell wall of Gram negative bacteria.
Organelle associated with cell division in Gram negative bacteria. There are two circumferential zones of cell envelope in which membranous elements of the envelope are ...
A term most commonly used to describe the fluid drained from the peritoneal cavity some time after the injection of an irritant solution. For example, a standard method for ...
General term for a membrane protein that increases the permeability of the plasma membrane to a particular molecule, by a process not requiring metabolic energy. See ...
Cells of a type or species in which a particular virus can complete its replication cycle.
Of a temperature-sensitive mutation, a temperature at which the mutated gene product behaves normally, and so the cell or organism survives as if wild-type (compare with ...
Genus of mice native to Central and North America.
A haem enzyme that catalyses reduction of hydrogen peroxide by a substrate that loses two hydrogen atoms. Within cells, may be localized in peroxisomes. Coloured ...
Organelle containing peroxidase and catalase, sometimes as a large crystal. A site of oxygen utilization, but not of ATP synthesis. In plants, associated with chloroplasts in ...
(1) The tendency of a cell to continue moving in one direction: an internal bias on the random walk behaviour that cells exhibit in isotropic environments.
(2) Of viruses that ...