bluuebunny/crossref_metadata_2025 huggingface dataset:
Homogenization of Soft Tissues (Rat Liver) in Iso‐osmotic Media
Authors: Graham John M
Published: September 2006

Rat liver and other soft tissue from small mammals can be homogenized using a Potter‐Elvehjem (Teflon/glass) homogenizer.
Isolation of a Light Mitochondrial Fraction from a Homogenate
Authors: Graham John M
Published: September 2006

A light mitochondrial fraction is one of the four principal fractions obtained by differential centrifugation of a mammalian tissue or cell homogenate. It is obtained by centrifugation of a 3000

g

supernatant at approx. 15 000

g

for 15 min. It contains principally the lighter mitochondria and most of the lysosomes and peroxisomes and any intact Golgi membranes and is used as a primary step in the purification of lysosomes and peroxisomes.
Fluorescent Labelling of Antibodies
Authors: Liddell JE
Published: September 2006

One of the most common fluorochromes used in immunocytochemistry and flow cytometry is fluorescein isothiocyanate (FITC), which produces a fluorescent apple‐green colour on exposure to ultraviolet light. Antibodies can be labelled with FITC via lysine residues.
Parasitism: Life Cycles and Host Defences against Parasites
Authors: Phillips R Stephen
Published: September 2006

Parasites must reach new hosts and to achieve this some have evolved very complex life cycles and in the process parasitize more than one host species. The host's defence system often controls the parasitic infection but cannot eliminate it.
Electrophoresis of DNA and RNA in Non‐denaturing Vertical Polyacrylamide Gels
Authors: Southern Edwin M
Published: September 2006

Electrophoresis in non‐denaturing polyacrylamide gels is a simple and useful technique for analysing RNA and DNA of less than 1000 bp. Separations are generally not affected by hidden nicks in the molecules but are subject to conformational factors of individual molecules
Immunoglobulin Superfamily and the Nervous System
Authors: Quarles Richard H
Published: September 2006

Members of the immunoglobulin superfamily include a large number of cell adhesion molecules and receptors that are important for mediating interactions between cells in the nervous system.
AIDS: Understanding HIV Transmission
Authors: Aichelburg Alexander C , Pett Sarah L , Cooper David A
Published: September 2006

For the implementation of successful prevention and intervention strategies in order to reduce HIV transmission and reduce the spread of HIV infection, it is essential to understand the variables associated with different modes of HIV transmission.
Intestinal Epithelial Cells: Immunological Aspects
Authors: Stadnyk Andrew W
Published: September 2006

Intestinal epithelial cells are active participants in the inflammatory and immune response because they (1) secrete certain cytokines and (2) are capable of presenting antigens to T lymphocytes. Antigen presentation is a requirement in the initiation of a specific immune response, whether humoral (antibody) or cellular.
Chromosome Rearrangements
Authors: Savage John RK
Published: September 2006

Structural changes in chromosomes can be induced by a wide variety of agents. Such changes, especially those that can be transmitted to future cell generations, play an important role in relation to genetic disease, congenital malformations and cancer. They are also used extensively for determining the extent of individual exposure in the case of radiation accident scenarios, and for environmental hazard screening in general.
Messenger RNA in Prokaryotes
Authors: Kushner Sidney R
Published: September 2006

Messenger RNAs (mRNAs) are molecules that represent the intermediate step in converting the genetic information carried in a cell's DNA to functional proteins. Structural features of mRNAs control both how effectively their contained data are translated into functional proteins and how rapidly they are destroyed.
Ribosomal RNA
Authors: Lafontaine Denis LJ , Tollervey David
Published: September 2006

All proteins are synthesized by ribosomes, large ribonucleic acid (RNA)–protein complexes that are the targets of several clinically relevant antibiotics. Ribosomes contain highly conserved ribosomal RNA (rRNA) species, which catalyse the key steps in protein synthesis, together with 70–80 proteins that play important roles in the correct folding and packaging of the rRNAs.
mRNA Splicing: Role of snRNAs
Authors: Padgett Richard A
Published: September 2006

Many small nuclear ribonucleic acids (snRNAs) of eukaryotic cells are involved in the maturation of primary transcripts of messenger RNAs (mRNAs). Certain snRNAs are involved in the formation and function of the spliceosome, a large ribonucleoprotein structure in which pre‐mRNA splicing takes place.
Heterochromatin and Euchromatin
Authors: Eissenberg Joel C , Elgin Sarah C R
Published: September 2006

Eukaryotes are characterized by the extensive packaging of their genomes, initially in a nucleosomal array, and further into higher order domains. Differential packaging is used as a mechanism of gene regulation, with stable silencing of large domains achieved by packaging the DNA into a heterochromatic structure.
DNAPackaging in Sperm
Authors: Hennig Wolfgang
Published: September 2006

The chromatin constitution of spermatozoa differs from that of all other cell types. The DNA is mainly associated with basic chromosomal proteins that are different from the otherwise universal histones, allowing packaging of the chromatin in a much smaller volume. Other biological functions in addition to a higher degree of chromatin compaction may be related to the difference in chromatin constitution but their nature is speculative.
Genes: Definition and Structure
Authors: Susman Millard
Published: September 2006

The word ‘gene’ has two meanings: (1) the determinant of an observable trait or characteristic of an organism, or (2) the DNA sequence that determines the chemical structure of a specific polypeptide molecule or RNA molecule. Since the observable characteristics of organisms include the chemical structures of their constituent molecules, these two definitions merge at the molecular level.
Allergy
Authors: Hanson Lars Å
Published: September 2006

Allergic diseases are defined as hypersensitivity reactions caused by the immune system reacting erroneously to external material to which it normally should not react. There are two types of allergic disease, of which the most common and complex are the atopic allergies such as asthma and hay fever. A smaller group of patients have contact dermatitis caused by delayed hypersensitivity reactions.
Vaccinia Virus Expression System
Authors: Falkner Falko G , Dorner Friedrich
Published: September 2006

The vaccinia virus expression system consists of genetically modified (recombinant) vaccinia viruses and vertebrate host cells; it allows transfer and expression of foreign (nonvaccinia) genes into the cytoplasm of infected animal cells.
RNA
Editing: Evolutionary Implications
Authors: Gray Michael W
Published: September 2006

The term ‘RNA editing’ describes a variety of mechanistically unrelated biochemical activities that alter RNA molecules after transcription by addition, deletion or substitution of nucleotides. A three‐stage model, illustrated by specific examples, can explain in a general way how RNA‐editing systems might arise and become fixed.
Protein Synthesis in Eukaryotes: IRES‐mediated Internal Initiation
Authors: Sonenberg Nahum
Published: September 2006

Internal initiation is an alternative mechanism to the general pathway of translation initiation in eukaryotes and involves the internal binding of ribosomes to a specific sequence in the messenger ribonucleic acid (mRNA) called the internal ribosome entry site (IRES). The mRNA 5′ cap structure and a cap‐binding protein, eukaryotic initiation factor (eIF) 4E, play a key role in the canonical mechanism of translation initiation. However, internal initiation is independent of the cap structure and eIF4E. IRES‐mediated translation initiation has been documented for viral and cellular mRNAs, and functions during mitosis and stress conditions, such as apoptosis and hypoxia.
Base Excision Repair,
AP
Endonucleases and
DNA
Glycosylases
Authors: Sander Miriam , Wilson Samuel H
Published: September 2006

Base excision repair is an important cellular mechanism that protects the integrity of DNA by repairing damage caused by alkylating agents and reactive oxygen species. The altered DNA base, and in some cases a few nucleotides adjacent to the altered base, is removed by excision, and the DNA is repaired by DNA synthesis and ligation.
Developmentally Programmed
DNA
Rearrangements
Authors: Fillingham Jeffrey S , Pearlman Ronald E
Published: September 2006

Developmentally programmed DNA rearrangements are structural reorganizations of the genome that occur reproducibly during the development of a variety of organisms. In the majority of cases, programmed DNA rearrangements function to alter gene expression. However, in a few cases a putative function has yet to be ascribed to large‐scale developmentally programmed DNA rearrangements.
Adenosine Triphosphate
Authors: Cohn Mildred
Published: September 2006

Adenosine triphosphate consists of the purine adenine linked through its N9 tod‐ribose via a β‐N‐glycosidic C(1′) linkage; the α‐phosphoryl group is linked via an ester linkage to the alcoholic O of ribose (C5′), and the β‐ and γ‐phosphoryl groups form anhydride bonds. The chemical energy stored in the anhydride bonds is released upon hydrolysis at the γ‐ or β‐phosphorus.
Glycolytic Pathway
Authors: Harper Edwin T , Harris Robert A
Published: September 2006

All cells use the glycolytic pathway to obtain energy in the form of ATP. The oxidative splitting of glucose is an evolutionarily ancient means of generating high‐energy phosphate compounds.
Saccharomyces cerevisiae
: Applications
Authors: Pausch Mark H , Kirsch Donald R , Silverman Sanford J
Published: September 2006

The yeast
Saccharomyces cerevisiae
has traditionally found useful applications in the production of food and alcoholic beverages. The completed sequence of its genome has revolutionized the use of yeast as a model system for the investigation of eukaryotic cell processes at a whole‐genome level. The production of enzymes and recombinant proteins and the development of drug screening assays are commercial applications of yeast cells.
Radical Enzymes
Authors: Sjöberg Britt‐Marie , Sahlin Margareta
Published: September 2006

Radical enzymes harbour a stable free radical in their polypeptide chain, which participates in catalysis. A growing number of enzymes are known to require a posttranslationally generated free radical for their proper functioning. The radical is generally used to remove a hydrogen atom from an unreactive position in the substrate, activating the substrate to undergo difficult chemistry. Some radical enzymes have unexpectedly been found to harbour a stable radical on an amino acid side‐chain that is distinct from the side‐chains of the active site region; during catalysis, the stable free radical interacts with the active site via electron or radical transfer and between turnovers it serves as a radical sink.
Cellulose: Structure and Distribution
Authors: Stone Bruce
Published: September 2006

Cellulose, a (1→4)‐β‐D‐glucan, is the most abundant carbohydrate polymer in the biosphere, where it may account for 50% of the carbon. Cellulose has a structural and protective function in walls of plant cells and surfaces of other organisms. The insolubility and high tensile strength of cellulosic materials arises from the regular, extended, ribbon‐like conformation of the individual molecules, their enormous lengths and their ability to aggregate into crystalline microfibrils.
Enzyme Classification and Nomenclature
Authors: Boyce Sinead , Tipton Keith F
Published: September 2006

Enzyme classification and nomenclature is a system that allows the unambiguous identification of enzymes in terms of the reactions they catalyse. This relies on a numerical system to class enzymes in groups according to the types of reaction catalysed and systematic naming that describes the chemical reaction involved.
Bacterial Restriction–Modification Systems
Authors: Gormley Niall A , Watson Mark A , Halford Stephen E
Published: September 2006

Restriction–modification systems allow bacterial cells to distinguish between their own DNA and any foreign DNA entering the cell, and to destroy the latter. They operate through two enzyme activities: a restriction endonuclease that cleaves the foreign DNA, and a modification methyltransferase that protects the host DNA.
Prokaryotic Replication Origins: Structure and Function in the Initiation ofDNAReplication
Authors: Messer Walter
Published: September 2006

Replication origins arecis‐acting sequences of a few hundred base pairs required for the replication of adjacent DNA. Their function is recognition of the correct start site and assembly of replication forks at this site.
DNA Topology: Supercoiling and Linking
Authors: Lindsley Janet E
Published: September 2006

The topology of DNA has a major impact on its structure and reactivity. Two different aspects of DNA topology are the linkage of two single strands comprising the DNA double helix, which can cause DNA supercoiling, and the linkage of double helixes in the form of knots and catenanes.
Nucleotide Degradation
Authors: Bierau Jörgen , van Kuilenburg André BP , van Gennip Albert H
Published: September 2006

Nucleotide degradation is an integrated process in all human cells that is intimately linked with the pathways of nucleotide synthesis and salvage. The clinical conditions associated with defects of enzymes catalysing nucleotide degradation provide a valuable insight into the importance of this network.
Cellulose: Biogenesis and Biodegradation
Authors: Stone Bruce
Published: September 2006

Cellulose is synthesized by plasma membrane‐bound cellulose synthase complexes found in some bacteria, slime moulds, some alveolates, chromists, in red and green algae, embryophytes and tunicates. Cellulose is degraded by many heterotrophic bacteria and fungi to soluble saccharides for use in growth and energy production. Bacterial, fungal and nematode plant pathogens use cellulases to gain access to the contents of plant cells by digesting their walls, and in embryophytes, cellulases have a role in cell wall development and differentiation.
Cardiovascular Disease and Congenital Heart Defects
Authors: Wang Qing , Chen Qiuyun
Published: September 2006

Heart disease (cardiovascular disease) is the leading cause of death in developed countries. Genetic factors play an important role in the pathogenesis of heart disease. The revolutionary advances in molecular genetics have provided new insights into the responsible genes and pathogenic mechanisms of heart disease, including congenital heart defects, arrhythmias, cardiomyopathies, heart failure and coronary artery disease.
Hydrophobic Interaction Chromatography
Authors: Jennissen Herbert P
Published: September 2006

Hydrophobic interaction chromatography involves the separation of protein molecules in their native and biologically active state owing to the differential interaction of these molecules with hydrophobic sites on the surface of a solid support. In the separation process, hydrophobic patches on the protein interact with hydrophobic molecules (e.g. alkyl residues) immobilized on the hydrophilic solid‐phase surface (agarose).
Thymidylate Synthesis
Authors: Kisliuk Roy
Published: September 2006

Thymidylate, an essential component of DNA, is synthesized from deoxyuridylate and methylenetetrahydrofolate by thymidylate synthase, but dihydrofolate reductase and serine hydroxymethyltransferase are required to regenerate methylenetetrahydrofolate. Inhibitors of the synthase and the reductase arrest cell replication and are used in the treatment of cancer.
Transfection of DNA into Mammalian Cells in Culture
Authors: Chalberg Thomas W , Phillips Julie E , Calos Michele P
Published: September 2006

Transfection is the transfer of DNA into cells and is a key technique for analysing mammalian cells. A variety of methods are employed to achieve transfection for use in genetic studies.
Alcoholism
Authors: Messing Robert O , Diamond Ivan
Published: September 2006

Alcoholism is a disease that results from neuroadaptive processes induced by repeated alcohol exposure and controlled by genetic factors. Although treatment for alcoholism is inadequate, current research suggests that new therapies will arise from understanding the genes and biochemical mechanisms that regulate alcohol consumption and craving.
Elongation Factors: Bacterial
Authors: Czworkowski John
Published: September 2006

Translational elongation factors are extra ribosomal proteins required for the addition of amino acids to the polypeptide being synthesized on the ribosome. Sequence comparisons and high‐resolution structural analyses of these proteins in bacteria have revealed striking homologies among them, with important implications for their evolution and function.
Transfer RNA Synthetase Editing of Amino Acids
Authors: Jakubowski Hieronim
Published: September 2006

Intrinsic binding energies of amino acids to aminoacyl‐tRNA synthetases are often inadequate to give the required accuracy of translation. This has necessitated the evolution of a second determinant of specificity, proofreading or editing mechanisms that remove errors in amino acid selection and prevent access of nonprotein amino acids to the genetic code. Editing of homocysteine and ornithine is linked to human disease.
Diffraction from Bilayers
Authors: Huang Huey W
Published: September 2006

X‐ray diffraction provided a direct proof for the hypothesis that the basic structural element of biological membranes is a bimolecular layer of phospholipid molecules. Diffraction from peptide–lipid mixtures can be used to study a great variety of membrane problems.
Protein Import into Endoplasmic Reticulum: Methods
Authors: Morrow Michael W , Brodsky Jeffrey L
Published: September 2006

Nascent secretory proteins and integral membrane proteins must translocate into the endoplasmic reticulum (ER). The regulation of translocation remains ill‐defined. Posttranslational translocation into the yeast ER can be measured using ER‐derived microsomes or reconstituted proteoliposomes and the mating pheromone precursor prepro‐alpha factor as the translocation substrate.
Acute Myelogenous Leukaemia
Authors: Lichtman Marshall A
Published: September 2006

Acute myelogenous leukaemia is the result of a malignant transformation of a primitive cell in the bone marrow. The neoplastic transformation imparts a growth and/or survival advantage to the cell. Leukaemic cells fill the haematopoietic cords of marrow. The functional result of this alteration is to impair blood cell production that normally occurs in the marrow, leading to a profound decrease in normal red cells (anaemia), white cells (leucopenia) and platelets or thrombocytes (thrombocytopenia) in the blood (Lichtman and Liesveld, 2000). Untreated, the disease results in death in weeks.
Human Gene Therapy: Risks and Safety Considerations
Authors: Ioannou Panos A , Vadolas Jim
Published: September 2006

Gene therapy has long been perceived as a once‐in‐a‐lifetime treatment that can give life‐long benefits. Some potential risks have been underestimated or have not received sufficient attention.
Intracellular Transport
Authors: Cross Robert A
Published: September 2006

Eukaryotic cells transport packets of components (membrane‐bounded vesicles and organelles, protein rafts, mRNA, chromosomes) to particular intracellular locations by attaching them to molecular motors that haul them along microtubules and actin filaments.
Actin and Actin Filaments
Authors: Ampe Christophe , Vandekerckhove Joël
Published: September 2006

The actin cytoskeleton is one of the main engines driving cell motility processes. In nonmuscle cells, various actin‐binding proteins orchestrate the dynamic turnover of actin filaments, generating force for the formation of cellular protrusions.
Muscle Contraction
Authors: Squire John M
Published: September 2006

Muscular contraction is one of the few biological processes that can be appreciated directly in our everyday lives. In the past few decades, a detailed understanding of the underlying molecular processes that produce force and movement has been obtained.
Interferons
Authors: Johnson Howard M , Torres Barbara A , Subramaniam Prem S
Published: September 2006

Interferons are endogenously produced proteins that regulate the immune response. They are multifunctional and have antiviral, cell regulatory and antitumour properties.
Complement
Authors: Holland M Claire H , Lambris John D
Published: September 2006

The mammalian complement system consists of a complex group of more than 35 soluble proteins and receptors that play an important role in innate and acquired host defence mechanisms against infection, and participate in various immunoregulatory processes. The functions mediated by complement activation products include phagocytosis, cytolysis, inflammation, solubilization of immune complexes, clearance of apoptotic cells and promotion of humoral immune responses.
Complement: Classical Pathway
Authors: Arlaud Gérard J , Colomb Maurice G
Published: September 2006

The classical pathway of complement is a major recognition system in innate immunity that is found in mammals and other animal species. It triggers various effector mechanisms via several multimolecular proteases – C1, the MBL–MASP‐2 and the ficolin–MASP‐2 complexes – to eliminate pathogenic microorganisms and other antigens from blood and tissues.
Complement: Terminal Pathway
Authors: Sodetz James M , Plumb Mnason E
Published: September 2006

Terminal pathway of complement refers to the sequence of interactions between components C5b, C6, C7, C8 and C9 that leads to the production of a ‘membrane attack complex’ possessing the ability to disrupt cell membranes.
Germinal Centres
Authors: Thielen Caroline , Heinen Ernst
Published: September 2006

Germinal centres are lymphoid structures appearing after an antigenic stimulation inside lymph follicles. During this germinal centre reaction, B cells not only undergo clonal amplifications but also affinity maturation and class switching of their immunoglobulins. These events, occurring under the control of T cells and in the peculiar environments created by the follicular dendritic cells, lead B cells to mature into B memory cells or into precursors of plasma cells.
Cytokine Receptors
Authors: Rose‐John Stefan
Published: September 2006

Cytokines are proteins that coordinate the activity of the immune system. Many cytokines belong to a family exhibiting a four‐helical topology. Receptors for these cytokines belong to the immunoglobulin superfamily and are all type I transmembrane proteins.
Haematopoiesis
Authors: Schmerer Matthew , Evans Todd
Published: September 2006

Haematopoiesis is the process of forming blood cells, which occurs during embryogenesis and throughout normal life.
Immunological Discrimination Between Self and Nonself
Authors: Heinen Ernst
Published: September 2006

Self–nonself discrimination is ensured mainly by lymphocyte receptors during lymphopoiesis and immunopoiesis, but antigen presentation also plays a role. Whether caused by infection or by other factors, alterations of lymphocytes or of antigen presentation can alter self‐tolerance and trigger autoimmune reactions.
Major Histocompatibility Complex: Human
Authors: Penn Dustin J , Ilmonen Petteri
Published: September 2006

The major histocompatibility complex (MHC) is a large genetic region that contains the most polymorphic loci known in humans and other vertebrates. MHC genes are the most intensively studied genes because they influence so many important traits, including resistance to infectious diseases, autoimmunity, compatibility of tissue transplants, spontaneous abortion, odour and mating preferences.
Major Histocompatibility Complex (MHC): Mouse
Authors: Melvold Roger W
Published: September 2006

The major histocompatibility complex (MHC) of the mouse, the
H2
(or
Histocompatibility‐2
; formerly abbreviated as
H‐2
) complex, is located on chromosome 17. It contains genes critical to the functioning of the immune system, the products of which are intimately involved in the earliest steps in the initiation of immune responses. There is great variation among these genes, a trait that is unusual and probably critical to the immune system.
Immunological Adhesion and Homing Molecules
Authors: Lucila Scimone M , von Andrian Ulrich H
Published: September 2006

Leucocytes must interact with other cells and extracellular matrix molecules to migrate from the bloodstream to lymphoid and nonlymphoid tissues, to detect and respond to antigen and to exert immune functions. Adhesion and homing molecules on the surface of leucocytes and interacting cells provide mechanical stability and contribute to the specificity of such interactions.
Vaccination of Humans
Authors: Rappuoli Rino
Published: September 2006

Vaccines have been the most effective tool for preventing and eliminating devastating infectious diseases, and thus improving the quality of life. Their role will be increasingly important in the medicine of the future because biotechnology has now broadened the targets of vaccination to include new infectious diseases, immunotherapy of tumours, chronic infections, autoimmunity and allergies.
Transplantation
Authors: Melvold Roger W
Published: September 2006

Transplantation is the transfer of cells, tissues or organs from one individual to another for a variety of purposes. It is important because it involves the replacement of missing, defective or damaged organs.
Autoimmune Disease: Pathogenesis
Authors: Bellone Matteo
Published: September 2006

Autoimmune diseases are a vast array of organ‐specific as well as systemic diseases, whose pathogenesis stems from the activation of bursa‐derived (B) and thymus‐derived (T) lymphocytes reacting against antigens of the body's own tissues (defined as ‘self’).
Dendritic Cells (T‐lymphocyte Stimulating)
Authors: Girolomoni Giampiero , la Sala Andrea
Published: September 2006

Dendritic cells are the principal antigen‐presenting cells for T lymphocytes, and direct both the quality and the quantity of the immune responses.
Monoclonal Antibodies
Authors: Zola Heddy
Published: September 2006

Monoclonal antibodies are antibodies with a unique specificity, generally made by cloning cells containing a particular antibody gene to produce a population of identical cells derived from a single cell, which all produce the same antibody. This should be contrasted with polyclonal antibodies found in the serum of immunized animals, which consist of a very diverse mixture of antibodies against many different molecules.
Antigen Processing
Authors: Sandberg Johan K , Glas Rickard
Published: September 2006

Processing of antigenic proteins into short peptide fragments is required for antigen recognition by T lymphocytes. Antigen recognition is mediated through cell surface presentation of the processed peptide fragments by major histocompatibility complex gene products.
Immune Haemolytic Anaemia
Authors: Packman Charles H
Published: September 2006

The immune haemolytic anaemias comprise a set of diseases characterized by shortened red blood cell survival (haemolysis) mediated by the action of antibodies and serum complement. The haemolysis is evidenced by a raised reticulocyte count in the absence of blood loss. Activity of the immune system is diagnosed by the presence of antibody or fragments of complement components (mainly C3 and C4) on the red blood cell surfaces.
Mixed T and B Lymphocyte Deficiency Disorders
Authors: Vihinen Mauno
Published: September 2006

Mixed immunodeficiency diseases are intrinsic defects of the immune system affecting both B and T cells and the adaptive immune system. Mixed or combined immune deficiencies may also be associated with or secondary to other diseases. Patients have severe symptoms and the condition can be fatal unless properly treated.
Spleen: Consequences of Lack of Function
Authors: Lewis Mitchell , Swirsky David
Published: September 2006

Loss of splenic function may be absolute or partial; it may be primary (e.g. splenectomy) or secondary to a range of medical disorders. The haematological effects and clinical complications depend on the extent to which various functions are compromised. The most serious complication, requiring lifelong control, is overwhelming postsplenectomy infection (OPSI).
Enzyme‐linked Immunosorbent Assay
Authors: Paulie Staffan , Perlmann Hedvig , Perlmann Peter
Published: September 2006

Enzyme‐linked imunosorbent assay (ELISA) is a highly sensitive immunoassay utilizing enzyme‐conjugated antibodies, with antigen or antibodies bound to a solid support. The assay measures changes in enzyme activities proportional to the antigen or antibody concentrations involved in the underlying immune reactions.
Cell Cycle: Regulation by Cyclins
Authors: Kitazono Ana A , Fitz Gerald Jonathan N , Kron Stephen J
Published: September 2006

The cell cycle is defined as the periodic occurrence of events that result in chromosome duplication (DNA replication in S phase) and separation (mitosis). These events are coordinately driven by the cyclin‐dependent kinases (CDKs). Cyclins are structurally related proteins whose levels fluctuate throughout the cell cycle. These CDK activators also impart distinct substrate specificity to CDKs for the temporal regulation of cell division.
Severe Acute Respiratory Syndrome (SARS)
Authors: Dandekar Ajai A , Perlman Stanley
Published: September 2006

SARS is an infection, caused by a novel coronavirus, which caused significant morbidity and mortality in 2003. Over the intervening period since SARS was recognized, much has been learned about the epidemiology, clinical disease and virology of this emerging infection.
Ageing and the Immune System
Authors: Aspinall Richard
Published: September 2006

The immune system is our own personal biological warfare machine that protects our body from infections by learning the difference between our own body tissues and the body components of invaders. Unfortunately, like all machines it is subject to normal wear and tear and gradually winds down with age; hence, an understanding of the most common causes of the deterioration in function could lead to an opportunity to reverse these processes and prolong the period of protection that the immune system provides.
Planetary Protection
Authors: Rummel John D , Billings Linda , Stabekis Pericles
Published: September 2006

Planetary protection is the practice of protecting solar system bodies (planets, moons, asteroids and comets) from Earth life and protecting the Earth from life that may be brought back from other solar system bodies. Planetary protection requirements for solar system exploration missions are established in consideration of the nature, goals and destination of a mission.
B Lymphocytes
Authors: Bondada Subbarao , Chelvarajan Ralph L , Gururajan Murali
Published: September 2006

Bone marrow‐derived (B) lymphocytes are antibody‐producing cells in the body. Antibody production is initiated upon recognition of antigen via a specific immunoglobulin receptor, and reception of growth and differentiation signals. B lymphocytes are also important for activation of helper T lymphocytes and are integral for the memory component of the immune response.
Arachidonic Acid Signalling in the Nervous System
Authors: Bazan Nicolas G
Published: September 2006

Arachidonic acid integrates phospholipid molecules of cell membranes. When arachidonic acid is released it becomes itself a messenger or is the precursor of a wide variety of arachidonic acid‐derived messengers. These bioactive lipids modulate the function of ion channels, receptors, neurotransmitter release, synaptic plasticity, glia–neuron relationships and programmes of neuronal gene expression. Therefore, arachidonic acid signalling participates in cell function and in certain pathologic conditions of the nervous system. The availability of arachidonic acid is regulated by the biosynthesis of specific phospholipids molecular species, their arachidonate remodelling, and the regulation of the release of arachidonic acid from membrane reservoirs and the subsequent conversion steps (e.g. cyclo‐oxygenation, lipooxygenation).
Axonal Transport and the Neuronal Cytoskeleton
Authors: Baas PW , Karabay A
Published: September 2006

The neuronal cytoskeleton is a system of highly organized polymers that provide architectural support for axons and dendrites, and also provide railways for the transport of various classes of cytoplasmic constituents. Molecular motor proteins use the energy derived from adenosine triphosphate hydrolysis for the transport of organelles along the cytoskeletal polymers and for the transport of the polymers themselves. Axons can traverse exceeding long distances in the body, and hence require sophisticated mechanisms of axonal transport in both the anterograde and the retrograde direction.
Dendrites
Authors: Ross William N
Published: September 2006

Dendrites are highly branched neuronal structures that form the main synaptic target of other nerve cells. The dendrites integrate this information, usually in the form of brief depolarizing or hyperpolarizing synaptic potentials, and generate the output of the neuron.
Memory: Clinical Disorders
Authors: Budson Andrew E , Price Bruce H
Published: September 2006

There are different forms of memory in the brain that use distinct anatomical structures to process various types of information in a variety of ways. Many disease processes can disrupt one or more of these forms of memory.
Synaptic Plasticity: Short Term
Authors: Zucker Robert S
Published: September 2006

The strength of synaptic transmission can increase or decrease during repetitive presynaptic activity. These changes, usually due to variations in the amount of transmitter released by each action potential, dynamically shape the information transfer characteristics of synapses.
Cortical Plasticity: Use‐dependent Remodelling
Authors: Ergenzinger Edward R , Pons Tim P
Published: September 2006

Sensory representations in the cortex have been shown to reorganize after alterations of peripheral input. Such reorganization may be induced by injury or through behavioural training.
Calcium Channel Blocking Agents
Authors: Striessnig Jörg , Glossmann Hartmut
Published: September 2006

Voltage‐dependent Ca
2+
signalling in electrically excitable cells is controlled by the activity of different types of voltage‐gated Ca
2+
channels. Selective channel blockers are important not only for treating cardiovascular diseases but also as pharmacological and biochemical tools for defining different channel types, determining their molecular structure, cloning channel subunits and refining their physiological and pathophysiological roles.
Chloride Channels
Authors: Akabas Myles H
Published: September 2006

Chloride channels are integral membrane proteins that regulate the movement of chloride ions across cellular membranes. They perform a vital role in physiological processes such as cell volume regulation, epithelial transport, the regulation of nerve and muscle cell membrane excitability and in determining the pH within cytoplasmic membrane‐bound organelles. Several genetic diseases are caused by mutations within chloride channel genes.
Pain and Analgesia
Authors: Craig AD , Sorkin LS
Published: September 2006

The accepted definition of pain is ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’. Analgesia is the alleviation or the absence of pain.
The Retinoid Cycle and Retinal Diseases
Authors: Palczewski Krzysztof , Baehr Wolfgang
Published: September 2006

The ‘retinoid cycle’ is a complex recycling system that replenishes the 11‐
cis
‐retinal chromophore of rod and cone visual pigments after its isomerization to all‐
trans
‐retinal by light. Recycling takes place in retinal rod and cone photoreceptor outer segments and the retinal pigment epithelium. Correct functioning of the retinoid cycle is of fundamental importance in vertebrate vision.
Ultrasound
Authors: Wells Peter NT
Published: September 2006

Nonionizing ultrasonic radiation penetrates biological soft tissues. Ultrasound that is scattered, attenuated and Doppler‐frequency‐shifted by tissues and contrast agents can be detected and processed safely to create one‐, two‐ and three‐dimensional images of structure and function, often in real time.
Invertebrate Neuropeptides
Authors: Nässel Dick R , Taghert Paul H
Published: September 2006

Invertebrate neuropeptides are found in neurosecretory cells, interneurons and motor neurons, as well as in endocrine cells of the intestine and in glandular cells of nonnervous tissue. Neuropeptides can act as neurohormones released into the circulation and/or as local neurohormones released in a paracrine fashion within the nervous system or at muscles or glands.
Somatosensory Systems
Authors: Goodwin Antony W
Published: September 2006

Sensations of touch, temperature, pain and movement of joints may be perceived from all parts of the body. Specialized receptor cells convert the stimuli producing such sensations into electrical signals that are processed in the somatosensory pathways of the nervous system.
Oculomotor System
Authors: Delgado‐García José M
Published: September 2006

The oculomotor system is composed of six extraocular muscles attached to the orbit and to the eyeball, extraocular motor neurons located in three different brainstem motor nuclei, and premotor centres and circuits involved in the generation and control of the different types of eye movement. Its precise functional design and robust biomechanics have allowed this motor system to survive, almost unchanged, across different trends in vertebrate evolution.
Memory in Fruit Flies and Nematodes
Authors: Holmes Celia M , Tanchuk Tracy L , Galloway Jennifer A , Peters Kevin R , Rankin Catharine H
Published: September 2006

A change in the behaviour of an organism that results from the individual's exposure to stimuli/events in the environment.
Drosophila melanogaster
and
Caenorhabditis elegans
have been the focus of much research in the areas of learning and memory.
Amphibian Brains
Authors: Smeets Wilhelmus JAJ , González Agustín
Published: September 2006

Amphibians mark the transition from an aquatic to a terrestrial lifestyle. From a phylogenetic point of view, amphibians are, therefore, considered of particular interest for a better understanding of evolutionary processes in brain organization of vertebrates.
Structural Genomics
Authors: Norvell John , Li Jiayin , Saltsman Kirstie , Berg Jeremy
Published: September 2006

Structural genomics is a new field that aims at the large‐scale determination of thousands of carefully selected protein structures. This endeavour will lead to a broad inventory of the protein structures found in nature, many of which will be of biomedical interest. Recent advances in experimental and computational technology, together with the wealth of protein sequence information provided by genome sequencing efforts, have made this formidable task possible.
Calcium and Neurotransmitter Release
Authors: Delaney Kerry R , Shahrezaei Vahid
Published: September 2006

Neural information encoded in the pattern of electrical activity in a neuron is transferred to other neurons by the release of chemical messengers. The mechanism of release of transmitter substances depends intimately on the coupling of neuronal depolarization to the elevation of calcium ion concentration at transmitter release sites.
Callose and Related Glucans
Authors: Stone Bruce
Published: September 2006

Callose is a water‐insoluble, linear (1→3)‐β‐
d
‐glucan found among embryophytes. It occurs in specialized cell walls of reproductive tissues, as a transient component of the cell plate in dividing cells and as deposits on plasma membranes following wounding or in physiological or pathological stress. Related glucans are found as bacterial capsules, as storage polysaccharides in euglenoid protozoa and chromistans (brown algae, yellow‐green algae, diatoms, water moulds and haptophytes), and as wall components and surface mucilages of yeasts and fungi.
Rheumatoid Arthritis
Authors: Wordsworth Paul , Holden Wendy
Published: September 2006

Rheumatoid arthritis is a common inflammatory disorder primarily affecting synovial joints but also other organs. It is characterized by immune‐driven chronic inflammation, relapses and remissions. It is strongly associated with the presence of rheumatoid factor in the blood and has a significant genetic predisposition, notably from certain immune response genes. Dramatic advances in therapies mean that progressive disability may no longer be inevitable.
Cnidaria (Coelenterates)
Authors: Shostak Stanley
Published: September 2006

Cnidaria (Gr.,
cnidae
, nettle) is a phylum of mostly marine Metazoa distinguished by cnidocysts, subcellular capsules containing an inverted tubule capable of everting and, in some cases, discharging venom. Sexual reproduction results in solid planula embryos that develop into columnar polyps. Asexual reproduction results in clones of polyps, polypoidal colonies or disk‐ to bell‐shaped sexual medusas (jellyfish).
Nematomorpha (Horsehair Worms)
Authors: Poinar George
Published: September 2006

The phylum Nematomorpha, the hairworms, occurs worldwide. All members are developmental parasites of aquatic or terrestrial invertebrates. One genus,
Nectonema
, is marine, while the remaining species occur in fresh water as free‐living stages or inside terrestrial hosts.
Arthropoda (Arthropods)
Authors: Blackstone Neil W
Published: September 2006

The Arthropoda is a phylum of ecdysozoan animals in which the epidermis produces a segmented, jointed and hardened exoskeleton, which has internal musculature.
Myriapoda (Including Centipedes and Millipedes)
Authors: Wright Jonathan C
Published: September 2006

The Myriapoda comprise four classes of terrestrial arthropods: Chilopoda or centipedes, Diplopoda or millipedes, Symphyla and Pauropoda. Myriapods are generally found in soil and litter and have a worldwide distribution. About 13 000 species are known.
Tardigrada
Authors: Wright Jonathan C
Published: September 2006

The Tardigrada comprise a phylum of about 800 described species of minute aquatic animals, showing clear affinities with the arthropods. Many inhabit interstitial or temporary water bodies, surviving periods of drying by cryptobiosis.
Rhynie Chert
Authors: Trewin Nigel H
Published: September 2006

The Rhynie chert (Scotland) was deposited by hot springs and contains exceptionally well‐preserved Early Devonian (c. 410 Ma) fossil plants and arthropods. The biota comprises the oldest well‐preserved terrestrial ecosystem on Earth, and the primitive terrestrial plants form the cornerstone of palaeobotany.
Terrestrialization (Precambrian–Devonian)
Authors: Selden Paul A
Published: September 2006

The emergence of plants and animals from the sea on to land – terrestrialization – was one of the major advances in the history of life on Earth. Evidence for early colonization is poor, but the fossil record reveals that by mid‐Palaeozoic times complex terrestrial ecosystems had become established.
The End Triassic Mass Extinction
Authors: Wignall Paul B
Published: September 2006

The end of the Triassic period, roughly Ma, was marked by one of the biggest mass extinction events in the history of life. Estimates of magnitude vary, but recent compilations suggest that it may have been one of the greatest extinction events of the fossil record. It has been estimated that nearly 70 terrestrial families and 60 marine families disappeared at the end of the Triassic, an extinction that corresponds to 23 and 18% extinction, respectively. The origins of this extinction remain enigmatic, tentative evidence for meteorite impact awaits widespread confirmation, while contemporaneous volcanism was intense but the nature of its damaging environmental impact is unclear.
Dinosaur Behaviour
Authors: Horner John R
Published: September 2006

Dinosaur behaviour concerned with reproductive activities and life history strategies can be hypothesized from the fossil record through studies of geology and comparative biology.
Adaptation and Constraint: Overview
Authors: Burd Martin
Published: September 2006

Adaptations are features of organisms that have evolved to perform fitness‐enhancing functions. Some conceivable adaptations or combinations of adaptations do not evolve because constraints (which may vary from lineage to lineage) limit the potential of adaptive evolution.
Speciation: Chromosomal Mechanisms
Authors: Nevo Eviatar
Published: September 2006

Chromosomal speciation is one of the major modes of the origin of new species through splitting of preexisting species. New species may originate by gene speciation, and also by the establishment of postmating reproductive isolation through structural chromosome rearrangements. The latter may induce low‐hybrid fitness, generated by macromutations, and even by micromutations, i.e. molecular changes causing meiotic disturbances (e.g. GC incompatibilities), though the latter awaits empirical support.
Speciation: Introduction
Authors: Wood Troy E , Rieseberg Loren H
Published: September 2006

Speciation is the formation of two or more new species from one ancestral species.
Extinction: Late Devonian Mass Extinction
Authors: McGhee George R
Published: September 2006

The Late Devonian mass extinction, which occurred 376 million years ago, is one of the ‘Big Five’ mass extinctions in Earth history. Suggested causes of the mass extinction include oceanic anoxia and global cooling. Two catastrophic models of global cooling are the present focus of research into the ultimate cause of the mass extinction: the volcanic winter hypothesis versus the impact winter hypothesis.
Ring Species and Speciation
Authors: Demuth Jeffery P , Rieseberg Loren H
Published: September 2006

A ring species comprises a group of populations whose range is distributed in the shape of a ring. These populations continuously intergrade around the ring except in one area, where populations are sympatric but do not exchange genes.
Thompsonian Transformations
Authors: Horder Tim
Published: September 2006

Thompsonian transformations are a graphical method for studying the relations of the morphologies of organisms in terms of overall patterns of modifications to their shared geometries.
Herpesviruses (Human)
Authors: Whitley Richard J
Published: September 2006

Human herpesvirus are a family of eight deoxyribonucleic acid (DNA) viruses that commonly inflict individuals. They consist of
Herpes simplex virus type 1
(HSV‐1),
Herpes simplex virus type 2
(HSV‐2),
Varicella‐zoster virus
(VZV),
Cytomegalovirus
(CMV),
Epstein
–
Barr virus
(EBV),
Human herpesvirus 6
(HHV‐6),
Human herpesvirus 7
(HHV‐7) and
Kaposi sarcoma‐associated herpesvirus
(KSHV or HHV‐8).
Tooth Induction
Authors: Thesleff Irma , Nieminen Pekka
Published: September 2006

The development of teeth is regulated by inductive tissue interactions of ectoderm and neural crest‐derived mesenchyme. Much of the molecular basis of these interactions has been clarified.
Xenopus
Embryo: β‐catenin and Dorsal–Ventral Axis Formation
Authors: Moon Randall T
Published: September 2006

During embryonic development of the amphibian,
Xenopus laevis
, the dorsal side of the embryo forms approximately opposite the sperm entry point, and the anterior and posterior axes are linked to this through the process of gastrulation. The mechanisms responsible for specification of the dorsal axis include a post‐fertilization cortical rotation that promotes a dorsal accumulation of β‐catenin, and the activation of a cascade of regulatory genes by the complexes of β‐catenin and HMG box transcription factors that start the process of gastrulation.
Signal Transduction Pathways in Development: the JAK/STAT Pathway
Authors: Naka Tetsuji , Ohkawara Tomoharu
Published: September 2006

The Janus Kinase (JAK)/signal transducer and achivator of transcription (STAT) pathway is activated not only by various cytokines such as interferon and interleukin, but also by many growth factors. This pathway plays a crucial role in the signal transduction of these factors.