bluuebunny/crossref_metadata_2025 huggingface dataset:
sno
RNA
s: Biogenesis, Structure and Function
Authors: Dragon François , Filipowicz Witold
Published: September 2006

The small nucleolar ribonucleic acids (snoRNAs) are involved in the processing and modification of ribosomal RNA precursors. They function in the form of ribonucleoproteins (snoRNPs).
RNA
Interactions in
m
RNA
Splicing
Authors: Newman Andrew J
Published: September 2006

Complex ribonucleoprotein machines called spliceosomes remove introns from nuclear mRNA precursors by mRNA splicing. A dynamic network of RNA interactions in the spliceosome plays crucial roles in splice site recognition and provides a structural framework for the catalytic steps of mRNA splicing.
Alternative Splicing: Cell‐type‐specific and Developmental Control
Authors: Valcárcel Juan , Smith Christopher WJ
Published: September 2006

Alternative splicing is a process that allows individual genes to produce multiple functionally distinct protein isoforms. The production of alternatively spliced isoforms is usually controlled in a cell‐type or developmentally regulated manner.
Lymphoid Development
Authors: Spain Lisa M , Kerr William G
Published: September 2006

Lymphoid cells (B cells and T cells) express antigen receptors which mediate the specific immune response. The development of lymphoid cells is tightly controlled to avoid autoreactivity and promote a diverse and useful repertoire of specificities.
Antiserum
Authors: Goodall Delia Margaret , Raykundalia Chandra
Published: September 2006

Antiserum is a general term used to denote the noncellular component of blood (serum) containing a mixture of antibodies (polyclonal), the donor usually having been actively immunized with a known antigen.
Latex and Laticifers
Authors: Kekwick Roy GO
Published: September 2006

Latex is a frequently milky plant exudate, often containing rubber, found in specialized cells called laticifers. Latex from Hevea brasiliensis is commercially important as the source of natural rubber.
Integrin Superfamily
Authors: Krissansen Geoffrey Wayne
Published: September 2006

Integrins are a superfamily of cell‐surface adhesion molecules formed from eight different β chains and 18 different α chains that assemble as heterodimers to mediate cell–cell and cell–matrix interactions. As sensors of the microenvironment, they control vital cellular functions such as cell growth, differentiation, programmed death and motility, and developmental processes; and in the adult they mediate tissue maintenance, blood clotting and immunity.
Transforming Growth Factor beta (TGFβ)
Authors: Serra Rosa
Published: September 2006

Transforming growth factor beta (TGFβ) is the prototype for a family of multifunctional secreted peptides that control many aspects of growth and development in a cell type‐specific manner.
Tumour Necrosis Factors
Authors: Grell Matthias , Scheurich Peter
Published: September 2006

The cytokine tumour necrosis factor is a major mediator of natural immunity and is thus a potent stimulus for many inflammatory and immune functions of the body.
Haptens
Authors: Rodkey L Scott , Nisonoff Alfred
Published: September 2006

A hapten is a chemical substance with a well‐defined stereochemical configuration that can bind to specific antibodies but is unable to elicit detectable immune responses unless it is coupled chemically to an immunogenic carrier molecule. Hapten studies have led the way to our contemporary understanding of numerous fundamental mechanisms in molecular and cellular immunology.
Allergens
Authors: Aalberse RC , Kapsenberg ML
Published: September 2006

Allergens are special types of (otherwise harmless) environmental antigens that elicit allergic reactions in sensitized individuals. One group of allergens includes small environmental or therapeutical chemicals that become allergenic after binding to self‐proteins (contact or drug allergy). Other allergens are inhaled, dietary or insect‐sting proteins that induce, mainly in predisposed individuals, an immune response characterized by immunoglobulin E production (atopic allergy).
Acquired Immune Deficiency Syndrome (AIDS)
Authors: Siliciano Robert F
Published: September 2006

The acquired immune deficiency syndrome (AIDS) is a potentially fatal transmissible disease, caused by
Human immunodeficiency virus type 1
(HIV‐1), which has claimed almost 20 million lives and infected over 34 million people. While there is as yet no cure or effective vaccine for AIDS, there are treatments that can forestall the development of overt disease and restore immune function.
Hypersensitivity: Immunological
Authors: Thomas Wayne R
Published: September 2006

Immunological hypersensitivity reactions are immune responses which lead to tissue damage. Classified into five types according to the mechanism of the tissue damage, they are involved in many important human diseases and disorders, such as anaphylaxis, asthma, food allergies, myasthenia gravis and systemic lupus erythematosus.
Antisense RNA
Authors: Delihas Nicholas
Published: September 2006

Antisense ribonucleic acids (RNAs) base pair with target RNAs and regulate target functions.
Two‐hybrid and Related Systems
Authors: Fields Stanley
Published: September 2006

The two‐hybrid system is a yeast‐based genetic method to detect and analyse protein–protein interactions. Related systems have been developed to detect DNA–protein, RNA–protein and small molecule–protein interactions.
Human Disease: Mouse Models
Authors: Popko Brian
Published: September 2006

Modelling human disease states or aspects of the disease process in animals has proven extremely valuable in furthering our understanding of specific illnesses, as well as in designing intervention therapies. Increasingly, the mouse is becoming the organism of choice for such studies.
Western Blotting
Authors: Bjerrum Ole J , Heegaard Niels HH
Published: September 2006

Western blotting is a method by which proteins that have been separated and subsequently immobilized on the surface of a membrane are exposed and probed. Many variants of each step exist.
Mass Spectrometry in Biology
Authors: Yates John R
Published: September 2006

Applications of mass spectrometry in biological studies range from identifying expressed proteins using two‐dimensional gel electrophoresis to identifying those proteins involved in protein–protein interactions.
Bunyaviridae
Authors: Guttieri Mary C , Schmaljohn Connie S
Published: September 2006

The family Bunyaviridae encompasses a large group of segmented RNA viruses that rely on arthropod vectors or rodent hosts for transmission.
Feline Leukaemia Virus
Authors: Jarrett Oswald
Published: September 2006

Feline leukaemia virus is a common pathogenic retrovirus of domestic cats, causing a variety of fatal diseases, including leukaemia and lymphosarcoma.
Filoviruses
Authors: Sanchez Anthony
Published: September 2006

Filoviruses are a group of mysterious and highly pathogenic RNA viruses that are primarily associated with equatorial regions of Africa. Filoviruses are genetically related to the more widely known mumps, measles and rabies viruses.
Flaviviruses
Authors: Barrett Alan DT
Published: September 2006

The flaviviruses are a group of medically important viruses that are mainly transmitted by mosquitoes and ticks; they include dengue, Japanese encephalitis, St Louis encephalitis, tick‐borne encephalitis, West Nile and yellow fever species.
Hepatitis B Virus
Authors: Jilbert Allison R , Mason William S
Published: September 2006

The human Hepatitis B virus is the prototype member of the family Hepadnaviridae. All hepadnaviruses, including both human and small animal species, are similar clinically and biologically, with intracellular replication of the viral DNA genome involving a unique reverse transcription process.
DNA Topology: Fundamentals
Authors: Mirkin Sergei M
Published: September 2006

Topological characteristics of DNA and specifically DNA supercoiling influence all major DNA transactions in living cells. DNA supercoiling induces the formation of unusual secondary structure by specific DNA repeats which can also affect DNA functioning.
Prokaryotic DNA‐binding Proteins
Authors: Karpel Richard L
Published: September 2006

DNA‐binding proteins are found in all organisms and play critical roles in DNA metabolism. Structure–function studies can be carried out on single‐strand specific binding proteins (SSBs), which function in DNA replication, recombination and repair.
Termination of Replication in Bacteria
Authors: Wilce Jackie A , Wake R Gerry , King Glenn F
Published: September 2006

Termination is the final stage of a round of replication in bacteria during which DNA replication is completed. In the case of a circular chromosome, this occurs when the two replication forks, progressing in opposite directions, meet and fuse in a specific region of the chromosome which is generally diametrically opposed to the site of initiation of DNA replication.
Evolutionary Developmental Biology:HoxGene Evolution
Authors: Manzanares Miguel , Krumlauf Robb
Published: September 2006

Hoxgenes are clustered homeobox‐containing genes present in all metazoans, with an evolutionary conserved function in conferring positional identity along the main body axis in bilaterians.
Mouse Early Development: Molecular Basis
Authors: Downs Karen M
Published: September 2006

Elucidating the cellular and molecular mechanisms involved in major aspects of pre‐ and post‐implantation development in the mouse forms an essential foundation for preventing birth defects in humans.
Cleavage and Gastrulation in Leech Embryos
Authors: Shankland Marty
Published: September 2006

More is known about embryonic development in glossiphoniid leeches than for any other annelid. A detailed knowledge of leech developmental biology lends insight into the mechanisms by which the body plans of adult animals are first established in the embryo.
Newcastle Disease Virus
Authors: Seal Bruce S , King Daniel J
Published: September 2006

Newcastle disease virus
is an economically important pathogen of poultry and other birds that has a worldwide distribution. The virus continues to pose a threat to poultry producers, and vaccination is commonly practised in many parts of the world. The virus may cause a conjunctivitis in humans.
Reoviruses
Authors: Coombs Kevin M
Published: September 2006

Reoviruses are infectious agents, transmitted by respiratory and fecal–oral routes, that are not major human pathogens. The viruses are distinguished by having a genome of 10 segments of double‐stranded RNA that is located inside a double‐layered, spherical nonenveloped protein capsid. The capsid is incompletely uncoated during viral replication.
Regeneration in Crustaceans and Insects
Authors: Hopkins Penny M
Published: September 2006

Regeneration of limbs occurs widely in the phylum Arthropoda. Limb nerves, hormones, and local cells/tissues exert control over the rate or nature of limb regeneration in the arthropods.
Regeneration of Vertebrate Tissues: Model Systems
Authors: Stocum David L
Published: September 2006

The four mechanisms of vertebrate regeneration are exemplified by several regenerating tissues used as experimental models in mammals and amphibians. Several strategies can be used to restore tissues that do not normally regenerate.
Affinity of Antigen–Antibody Interactions
Authors: Goldblatt David
Published: September 2006

Antibody affinity is the strength with which antibody binds to its target antigen. It is influenced by a variety of factors including valency and the precise fit of the antigen in the antigen binding groove. Antibody affinity increases over time following contact or repeated immunization with certain types of antigen. The affinity of an antibody may have an influence on its function.
Antigen–Antibody Complexes
Authors: Eggleton Paul
Published: September 2006

Antigen–antibody complexes are formed when the body's immune system raises antibodies against antigenic determinants of host or foreign substances that recognize and bind to the unwanted molecules. Normally, the immune complexes that are formed are cleared by the cellular immune system, but when an excess of antibody or antigen is present, the immune complexes are either detected in tissues or involved in the pathogenesis of tissue lesions in a variety of diseases.
Cell Separation Techniques Used in Immunology
Authors: Hunt Simon V
Published: September 2006

General methods for separating subpopulations of cells involved in immune responses include those based on differences in cell density, surface adherence, and the presence or absence of characteristic cell surface molecules, especially those recognized by CD monoclonal antibodies. The choice of technique depends on the scale of the separation; the trade‐offs between starting fraction, purity and yield; and the sophistication and cost of reagents and apparatus. Licensing for clinical use may impose constraints on a method's suitability.
Hypersensitivity: T Lymphocyte‐mediated (Type IV)
Authors: Ampel Neil M
Published: September 2006

Five types of hypersensitivity reactions have been described: types I, II, III and V depend on the interaction of antigen with antibody and have been termed immediate; type IV depends on the interaction of antigen with T lymphocytes and has been called delayed‐type hypersensitivity, or DTH.
Histones: from Gene Organization to Biological Roles
Authors: Doenecke Detlef
Published: September 2006

Histones are a group of highly conserved small basic proteins that form the major part of the protein moiety of eukaryotic chromosomes. Their function in structuring the nucleosomes as the basal chromosomal deoxynucleoprotein repeat units is modulated by several different types of posttranslational modifications and varied patterns of histone structure variants contributing to the nucleosome structure.
Karyotype Analysis and Chromosome Banding
Authors: Bickmore Wendy A
Published: September 2006

A series of reproducible bands across metaphase chromosomes can be revealed by some treatments. These chromosome bands not only allow the identification of normal and abnormal chromosomes but they also tell us about fundamental aspects of the chromatin structure and compartmentalization of the genome.
Centromeres
Authors: Choo KH Andy
Published: September 2006

The centromere is the chromosomal substructure that underpins the accurate partition of newly replicated sister chromatids between daughter cells during cell division.
Immunofluorescence
Authors: Fritschy Jean‐Marc , Härtig Wolfgang
Published: September 2006

Immunofluorescence is a biological assay combining the use of antibodies and fluorescent molecules for the detection of specific targets in cells and tissues. The technique is very sensitive and versatile and finds numerous applications in the fields of immunology, cell morphology, genetics, diagnostics and histopathology.
Lymphocytes: Gamma Delta
Authors: Bonneville Marc , Fournié Jean‐Jacques
Published: September 2006

γδ Lymphocytes are a subset of T lymphocytes that express the γδ receptor for antigens. They are distinct from the other subset, αβ.
Gene Silencing in Development (
Drosophila
)
Authors: Brock Hugh W , Milne Thomas A
Published: September 2006

Gene silencing is required to stably repress genes, even after cell division, and most require a stable change in DNA or the proteins bound to the DNA of the silenced gene.
Imprinting (Mammals)
Authors: Surani M Azim
Published: September 2006

Genomic imprinting confers functional differences on parental genomes in mammals. This is due to germ line‐specific modifications of imprinted genes that regulate their parent of origin dependent expression in embryos.
Natural Antibodies
Authors: Zouali Moncef
Published: September 2006

Natural antibodies are antibodies present in the circulation of an animal that has not been previously exposed to the corresponding antigen. This subset contrasts with immune antibodies, which are produced in response to the introduction of antigen to the immune system.
Phagocytosis: Enhancement
Authors: Peiser Leanne , Gordon Siamon
Published: September 2006

The phagocytosis of pathogens, tissue debris or apoptotic cells by macrophages and neutrophils may be enhanced by host molecules called opsonins, which allow the recognition and subsequent ingestion of the particles by phagocytic receptors. There are numerous opsonins, including complement‐derived proteins such as iC3b and immunoglobulin G, which are recognized by specialized receptors including complement receptor type 3 and FcγR.
Skin: Immunological Defence Mechanisms
Authors: Nickoloff Brian J
Published: September 2006

Human skin is the largest organ of the body providing a protective coat to ensure that exogenous ‘noxious’ agents do not jeopardize the function of vital internal organ systems. Being situated at the interface between external and internal milieus, a number of remarkable structural and functional characteristics of skin have been delineated that contribute to its effectiveness at maintaining homeostasis.
T Lymphocytes: Helpers
Authors: Kondo Takayuki , Martin Roland
Published: September 2006

Helper T lymphocytes are MHC class II restricted CD4+ T cells, and can be divided into several subsets by cytokine releasing patterns such as T‐helper 1 (TH1) and T‐helper 2 (TH2). Helper T cells orchestrate antibody production and cellular immune responses by crossregulating each other, and each THsubset plays a distinct role in host defence and autoimmunity.
Graft Rejection: Mechanisms
Authors: Orosz Charles
Published: September 2006

The body uses a number of inflammatory and immune responses to promote clinical and experimental graft rejection. Various clinical strategies have been designed to treat transplantation patients who develop acute and hyperacute rejection.
Immunodeficiency, Primary: Affecting the Innate Immune System
Authors: Heyworth Paul G
Published: September 2006

The innate immune system is the body's first line of defence against potentially infectious microorganisms. There are a number of primary (inherited) disorders that can affect the different components of the system and leave the body susceptible to infection.
Immunosuppression: Use in Transplantation
Authors: Humar Abhinav , Matas Arthur J
Published: September 2006

Clinical immunosuppression is the reduction of undesirable immunologic activity, usually achieved using immunosuppressive drugs. It is used in a variety of medical conditions, including inflammatory diseases and autoimmune disorders, but its most common application is in the field of organ transplantation.
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.
Adhesive Specificity and the Evolution of Multicellularity
Authors: Vleminckx Kris
Published: September 2006

Most of the cells in a multicellular organism are connected to each other and/or attached to a substrate. Physically this is mediated by adhesion molecules exposed on the cell surface and attached to the cell membrane either by covalent linkage to the lipid bilayer or by a membrane spanning region.
Autoimmune Disease
Authors: Volpé Robert
Published: September 2006

The term autoimmunity describes the inappropriate reaction of the immune system against one or more of the organism's own tissues. It does not necessarily imply any tissue damage or dysfunction. When there is tissue infiltration, damage and/or dysfunction, the condition is termed autoimmune disease.
Haematopoietic Growth Factors
Authors: Thomas Daniel , Lopez Angel F
Published: September 2006

Haematopoietic growth factors regulate the production of all the cellular elements of blood by stimulating the proliferation, survival and differentiation of haematopoietic cells in various stages of maturation and also enhancing certain mature cell functions.
Ozone and Reactive Oxygen Species
Authors: Allan Andrew C , Fluhr Robert
Published: September 2006

Increasing levels of the pollutant ozone are likely to have a dramatic effect on future plant productivity. Ozone's damaging effect on the plant is primarily via an induction of cellular reactive oxygen species (ROS).
Plant Respiration
Authors: Hill Steven A
Published: September 2006

Respiration is an important feature of the metabolism of higher plant cells. Because plants synthesize all their organic molecules from inorganic materials and are sedentary, there are unique features that distinguish plant respiration from animal respiration.
Plant Macro‐ and Micronutrient Minerals
Authors: Grusak Michael A
Published: September 2006

All plants must obtain a number of inorganic mineral elements from their environment to ensure successful growth and development of both vegetative and reproductive tissues. A total of fourteen mineral nutrients are required.
Photosynthesis: Light Reactions
Authors: Bendall Derek S
Published: September 2006

In plants and cyanobacteria the ‘light reactions’ of photosynthesis use light energy to generate reducing power in the form of nicotinamide–adenine dinucleotide phosphate (NADPH) and metabolic energy as adenosine triphosphate (ATP), which are subsequently used in the ’dark reactions’ to drive the reduction of carbon dioxide and synthesis of carbohydrate. The light reactions, as conventionally defined, are actually a complex series of processes which include not only reactions in which light participates directly, but also closely associated reactions that indirectly depend on light.
Nucleic Acids: General Properties
Authors: Soukup Garrett A
Published: September 2006

Nucleic acids are biological polymers generally composed of four different monomer units termed nucleotides. The unit length of one molecule can be as much as one billion nucleotides. Although the biological roles that nucleic acids fulfil are diverse, the structure and function of each molecule is elaborated from a common set of general properties.
Protein–Ligand Interactions: Molecular Basis
Authors: Fisher Harvey F
Published: September 2006

The binding of ligand (typically, a small molecule) to a highly specific site on a protein molecule is an obligatory initial event in almost every life process.
Protein–Protein Interactions
Authors: Lakey Jeremy H , Gokce Isa
Published: September 2006

Highly specific protein–protein interactions feature in all areas of biochemistry. The genome sequences now available are increasing both our knowledge of the protein composition of cells and the need to understand how they interact.
Protein–DNA Interactions: Structure and Energetics
Authors: Kerppola Tom K
Published: September 2006

DNA‐binding proteins recognize specific DNA sequences by a combination of molecular interactions. Protein–DNA complex formation is frequently accompanied by conformational changes in one or both components of the complex. Protein–DNA interactions differ in several respects from most other ligand–receptor interactions in cells, and these characteristics place special requirements on the energetics and dynamics of protein–DNA interactions and explain many of the special properties of these complexes.
Protein–DNAInteractions: Polyelectrolyte Effects
Authors: Shaner SL
Published: September 2006

The stability of noncovalent protein–DNA complexes is typically sensitive to the ionic composition of the solution, in a manner that is dependent on the specific ion concentrations and is not a simple ionic strength effect. One important origin of this sensitivity to solution conditions is the polyelectrolyte effect.
Checkpoints in the Cell Cycle
Authors: Novák Béla , Sible Jill C , Tyson John J
Published: September 2006

Surveillance mechanisms stop progression through the cell cycle at specific checkpoints (at the G1 → S, G2 → M and metaphase → anaphase transitions) if certain crucial requirements have not been met. These checkpoint controls are essential for maintaining genomic integrity and balanced growth and division.
Protein–
DNA
Complexes: Specific
Authors: Strauch Mark A
Published: September 2006

Sequence‐specific DNA‐binding proteins recognize and interact with discrete base sequences in the genome to regulate fundamental metabolic processes.
Amino Acid Degradation
Authors: Sawers Gary
Published: September 2006

Degradation of amino acids results in the amino group either being incorporated into other nitrogenous compounds or being excreted as ammonia or urea, while the carbon skeleton is catabolized to one of a few common metabolic intermediates.
Eicosanoid Biosynthesis
Authors: Fernandez Ana Z , Jain Mahendra Kumar , Apitz‐Castro Rafael
Published: September 2006

Eicosanoids are the major products derived from the cellular metabolism of arachidonic acid by the enzymes cyclooxygenase and lipoxygenase. The eicosanoids comprise prostaglandins, thromboxanes, prostacyclins, leucotrienes and lipoxins.
Lipases: Digestion of Neutral Lipids; Physiological and Pathological Implications
Authors: Hamosh Margit
Published: September 2006

Fat digestion is a complex process that starts in the stomach through the action of gastric lipase and continues in the intestine, where colipase‐dependent pancreatic lipase and cholesterol ester lipase complete the process of triglyceride and cholesteryl ester hydrolysis, respectively. Bile salts and partial products of triglyceride hydrolysis are essential for the emulsification of these nonpolar lipids in the aqueous milieu of the intestinal lumen.
Adrenaline and Noradrenaline
Authors: Goldstein David S
Published: September 2006

Noradrenaline (norepinephrine) is the main neurotransmitter of the sympathetic nervous system, and adrenaline (epinephrine) is the main hormone secreted by the adrenal medulla. Both compounds are catecholamines.
Blood Clotting: General Pathway
Authors: Berkner Kathleen L
Published: September 2006

Haemostasis is the process that maintains blood in a fluid state while retaining the capacity to respond to injury by forming a clot to stem blood loss. This process comprises a complex interplay between circulating and cellular proteins which regulate the formation of fibrin and the fibrin/platelet haemostatic plug at the site of injury, and defects in the individual proteins can lead to bleeding disorders (haemophilia). Several of the proteins that participate in haemostasis require vitamin K for function, and inhibition of vitamin K action is commonly used in anticoagulant therapy.
Bioluminescence
Authors: Lee John
Published: September 2006

Bioluminescence is high‐efficiency generation of light by biological systems. It is the result of high‐quantum‐yield chemiluminescent reactions in a protein environment.
Tumours: Immunotherapy
Authors: Rubinstein Mark P , Cole David J
Published: September 2006

Tumour immunotherapy is an anticancer approach in which the patient's immune system is either enhanced or augmented to mediate tumour regression. Although some therapeutic approaches in use today are nonspecific, most protocols are designed to be antigen specific; the latter can be accomplished by either adoptive transfer or vaccination.
Chromosomal Genetic Disease: Structural Aberrations
Authors: Moore Charleen M , Best Robert G
Published: September 2006

Structural chromosome rearrangements are changes in the physical structure of chromosomes that may result in birth defects, mental retardation and increased risk for infertility or pregnancy loss.
Immune Deficiency: Severe Combined Immune Deficiency
Authors: Ananworanich Jintanat , Shearer William T
Published: September 2006

Severe combined immune deficiency (SCID) represents a diverse group of disorders caused by genetic defects in T‐cell development and signalling pathways, the most common being the mutation of the interleukin‐2 receptor γ chain leading to X‐linked SCID.
Genetic Variation: Human
Authors: Armour John AL
Published: September 2006

Many different types of genetic variation can be observed in the DNA of modern humans. Nevertheless, humans have relatively little genetic variation compared with many other species, suggesting a recent common origin for
Homo sapiens
. Some of this variation may have functional consequences, for example in disease states and complex characters such as stature or intelligence, but much variation in DNA appears to be neutral.
Cancer Cytogenetics
Authors: Roberts Paul
Published: September 2006

Cancer development is often associated with the acquisition of nonrandom chromosome abnormalities. Knowledge of the nature and mechanisms of action of the genes involved plays an important part in our quest to understand this complex disease.
Chromosome Rearrangement in Evolution
Authors: Burt David W
Published: September 2006

Species differ in the number and shape of chromosomes as well as in anatomy, physiology and genetics. Chromosome rearrangement may play an important role in the evolution of species both in how their genomes are expressed and in mechanisms of reproductive isolation.
Caenorhabditis elegansEmbryo: Determination of Somatic Cell Fate
Authors: Schnabel Ralf
Published: September 2006

Although embryogenesis appears to be determinate inC. elegansbecause of its stereotype cell lineage, the mechanisms of regional specification typical for indeterminate development are nevertheless used. Early on, blastomere identities are specified by binary decisions, and each blastomere gives rise to a coherent region of the embryo containing different somatic cell fates.
Tunicate Embryos and Cell Specification
Authors: Satoh Noriyuki
Published: September 2006

The ubiquitous ascidians (sea squirts) are the most common
tunicates. Cell fate restriction occurs relatively early in ascidian embryos,
which show a mosaic mode of development. Molecular identification of cell
lineage determinants and elucidation of the machinery responsible for the
localization and of the mode of action of the determinants is necessary for
the understanding of cell fate determination in ascidian embryos.
Molecular Phylogeny Reconstruction
Authors: Kumar Sudhir , Filipski Alan J
Published: September 2006

Molecular phylogenetics deals with the inference of evolutionary relationships among individuals, populations, species and higher taxonomic entities using molecular data.
Fossils in Phylogenetic Reconstruction
Authors: Sumrall Colin D
Published: September 2006

Palaeontologists have begun to adapt mathematical algorithms to phylogenetic reconstruction and interpretation of the fossil record. Whereas most palaeontologists prefer phylogenetic methods that rely predominantly on character evidence, such as that used by most systematists, others have developed methodologies that variously incorporate temporal data, rely strictly upon temporal data, or utilize temporal data in testing phylogenetic hypotheses.
Geological Time: Principles
Authors: Prothero Donald R
Published: September 2006

Geologists determine the age of events in the geological past by relative dating (establishing which event comes first, usually by superposition and crosscutting relationships) and by numerical dating (obtaining a numerical age estimate on an event, usually by radioisotopic dating of interbedded or crosscutting igneous rocks). From these dating methods, geologists have determined that the earth is 4.5 billion years old, and that most events in the geological past took place millions to hundreds of millions of years ago.
Chordata (Chordates)
Authors: Bone Quentin
Published: September 2006

The Chordata are a group of animals characterized by a dorsal tubular nerve cord, a notochord and gill slits. The group includes the Vertebrata (Craniata), Tunicata, Acrania and Conodonta.
Chondrichthyes (Sharks, Rays and Chimaeras)
Authors: Gottfried Michael D
Published: September 2006

Chondrichthyes is the class of vertebrates that includes sharks, rays and chimaeras. These relatives of bony fishes are characterized by an internal skeleton of cartilage rather than true bone.
Caudata (Salamanders)
Authors: Milner Andrew R
Published: September 2006

The order Caudata is the amphibian group comprising the living salamanders (including newts, mud‐puppies, axolotls, sirens, congo eels and the olm) and their extinct relatives back to their divergence from the Salientia (frogs). The term Urodela is similar in use but applies only to the crown group, i.e. living salamanders and the fossil forms falling within the group from the point where the living forms started to diversify.
Testudines (Tortoises, Turtles and Terrapins)
Authors: Meylan Peter A
Published: September 2006

Testudines is an order of reptilian tetrapods commonly called turtles (including tortoises and terrapins). All fossil and living members of the group have a shell that encloses both of the limb girdles. The group has its origins in the Triassic and is now represented by 13 living families, many of which contain species in danger of extinction.
Pterosauria (Pterosaurs)
Authors: Unwin David M
Published: September 2006

Pterosaurs were a highly successful group of carnivorous reptiles with well‐developed wings and an excellent flight ability. They lived alongside the dinosaurs, survived for more than 140 million years and filled many habitats now occupied by birds and bats.
Monotremata
Authors: Musser Anne M , Archer Michael
Published: September 2006

Monotremes (the platypus and echidnas) are primitive yet specialized egg‐laying mammals, today found only in Australia and New Guinea but historically part of the fauna of the ancient supercontinent of Gondwana.
Insectivora (Insectivores)
Authors: Whidden Howard P
Published: September 2006

The Insectivora is the order of mammals containing the shrews, moles, hedgehogs, golden moles, solenodons and tenrecs.
Old World Monkeys
Authors: Hartwig Walter Carl , Rosenberger Alfred L
Published: September 2006

Old World monkeys, or cercopithecoids, include macaques, baboons, langurs, vervets, guenons, and a variety of other rarer species in Africa and Asia.
New World Monkeys
Authors: Rosenberger Alfred L , Hartwig Walter Carl
Published: September 2006

New World monkeys are the living (nonhuman) primates of South and Central America.
Apes
Authors: Andrews Peter
Published: September 2006

Apes are the primates most closely related to humans. They are very similar genetically, and they share characters such as broad flat trunks and lack of a tail that distinguish them from all other primates.
Rodentia (Rodents)
Authors: Montuire Sophie
Published: September 2006

The rodents include more than 30 families and 350 genera. The distribution of the rodent species is worldwide and they occupy almost every kind of ecological niche. Most species are terrestrial, but some are specialized for underground, semiaquatic or arboreal life. Rodents are abundant and very diverse in form, adaptations and geographic distribution.
Echiura (Unsegmented Protostome Worms)
Authors: Saiz‐Salinas José I
Published: September 2006

Echiurans are unsegmented protostome worms with setae and a proboscis that cannot be retracted into the body.
Pogonophora (Beard Worms)
Authors: Rouse Greg W
Published: September 2006

Pogonophora represents a group of segmented worms living in chitinous tubes, largely restricted to deep‐sea environments such as methane seeps and hydrothermal vents. They are unusual in lacking a mouth and anus as adults, and in having the gut tissue massively expanded and filled with symbiotic bacteria, through which they gain their nutritional requirements.
Bryozoa (Ectoprocta: ‘Moss’ Animals)
Authors: Nielsen Claus
Published: September 2006

The Bryozoa are a phylum of small, colonial, almost exclusively sessile, aquatic organisms. More than 4000 living species are known, and the fossil record comprises about 20 000 species. Most species encrust stones or algae, others form erect bushes, and a few form free‐living colonies. Bryozoans are found in all oceans and many freshwater areas.
Echinodermata
Authors: Paul Christopher RC
Published: September 2006

The Echinodermata form a distinctive phylum of exclusively marine animals. They are characterized by an extensive water vascular system, an internal skeleton composed of many plates with a meshwork structure (stereom), and pentameral symmetry.
Hemichordata (Acorn Worms)
Authors: Welsch Ulrich
Published: September 2006

The hemichordates are marine invertebrate organisms forming a phylum within the ‘Deuterostomia’; they comprise two classes, Pterobranchia and Enteropneusta.
Messel
Authors: Schaal Stephan
Published: September 2006

The Messel site became famous with the discovery of its extraordinarily well‐preserved fossils of Middle Eocene age. The fauna and flora suggest a European subtropical rainforest 49 million years ago. The spectrum of fossil species at this site is unusually extensive.
Diversity of Life through Time
Authors: Miller Arnold I
Published: September 2006

Global diversity can be defined as the number of taxa extant in the present day or at any given time in the geological past. Using data collected from the fossil record, palaeontologists have reconstructed the trajectory of global biodiversity throughout the history of life. Documentation of this trajectory has fuelled a vigorous research agenda focusing on the causes of major diversity increases (radiations), decreases (extinctions) biotic transitions and the relationship between diversification in the marine and terrestrial realms.
Tiering on Land – Trees and Forests (Late Palaeozoic)
Authors: Cleal Christopher Jonathan
Published: September 2006

Although trees first appeared in the Late Devonian (370 Ma), the earliest extensive forests were the tropical coal forests of the Late Carboniferous (310–300 Ma).
Post‐Permian Radiation
Authors: Twitchett Richard J
Published: September 2006

Events at the close of the Permian, 251 Ma, led to the most severe mass extinction of the Phanerozoic. Seposki's ‘Palaeozoic Fauna’ suffered worst; the surviving groups, more ‘modern’ in aspect, were those that would seed the post‐Permian radiation and produce the ‘Mesozoic Marine Revolution’ of Vermeij.
Quaternary Life on Land
Authors: Elias Scott A
Published: September 2006

The Quaternary is the most recent geological period. It is most commonly called ‘the ice age’, although that term suggests the unremitting presence of glacial ice sheets, which is certainly not the case.
Human Evolution: Radiations in the Last 300 000 Years
Authors: Pearson Osbjorn M
Published: September 2006

Homo sapiens
and Neanderthals (
Homo neanderthalensis
) evolved from
Homo heidelbergensis
in the last 300 000 years.
H. sapiens
subsequently spread throughout the world; all other hominins disappeared. The Out of Africa and multiregional models offer different explanations for this pattern.
Extinction: Late Devonian Mass Extinction
Authors: McGhee George R
Published: September 2006

The Late Devonian mass extinction, which occurred 364 million years ago, is one of the ‘Big Five’ mass extinctions in Earth history. Suggested causes of the mass extinction include oceanic anoxia, global cooling and asteroid impacts.
Species Selection
Authors: Crespi Bernard J
Published: September 2006

Species selection is a hypothesized cause of macroevolutionary trends or stasis, which requires that variation among taxa in their traits causes variation in their speciation and extinction rates.
Photosynthesis and Respiration in Cyanobacteria
Authors: Vermaas Wim FJ
Published: September 2006

Cyanobacteria are among the very few groups that can perform oxygenic photosynthesis and respiration simultaneously in the same compartment, and some cyanobacterial species are able to fix nitrogen. This combination of metabolic pathways is unusual and this metabolic flexibility may be responsible for the evolutionary hardiness of the cyanobacteria and their ability to thrive under a wide range of conditions.
Evolutionary Ideas: Pre‐Darwinian
Authors: Bowler Peter J
Published: September 2006

The
modern theory of evolution emerged in the mid‐nineteenth century, but ideas
about the natural origin of species were discussed from the ancient Greeks
onwards and were actively debated (although not widely accepted) by the time
Darwin began his researches.
Evolutionary Ideas: The Eclipse of Darwinism
Authors: Bowler Peter J
Published: September 2006

Following the acceptance of evolutionism, biologists tried – with limited success – to reconstruct the history of life on Earth, and also debated the mechanism of evolution. Many alternatives to Darwinian natural selection were tried out, including a revived version of Lamarck's theory of the inheritance of acquired characters, and evolution by saltations (which paved the way for Mendelian genetics).
Evolutionary Ideas: The Modern Synthesis
Authors: Bowler Peter J
Published: September 2006

By the middle decades of the twentieth century a synthesis between Mendelian genetics and the Darwinian selection theory had emerged that attracted the support of the majority of evolutionary biologists. The genetical theory of natural selection was applied to field studies and palaeontology, giving rise to disagreements among biologists and historians over the nature and ultimate impact of the synthesis.
Adaptations: Meanings
Authors: Reeve Hudson K , Sherman Paul W
Published: September 2006

An adaptation is the phenotypic variant that has the highest reproductive success among a well‐specified set of variants in a given environment.
Selection: Units and Levels
Authors: Crespi Benard J
Published: September 2006

Analysis of units and levels of selection allows determination of where and how natural selection takes place, and how it causes evolutionary change in genes and organisms.
Sex: Advantage
Authors: Jokela Jukka
Published: September 2006

One of the most intriguing quests in evolutionary biology is to find an explanation for why sexual reproduction is so common in nature, and how it is maintained. In theory, sexual reproduction is expected to carry considerable costs when compared with asexual reproduction. Competing hypotheses for the advantage of sex range from better resistance to coevolving parasites to efficient clearance of deleterious mutations.
Reproductive Strategies
Authors: Fox Gordon A
Published: September 2006

‘Reproductive strategies’ refers to the evolutionary and ecological consequences of schedules of reproduction, mortality, and growth in a life cycle. ‘Strategies’ in this context should be understood as ‘syndromes’ that affect Darwinian fitness, rather than as implying conscious intent.
Mutational Biases
Authors: Yampolsky Lev Y
Published: September 2006

Mutational biases are systematic differences in mutation rates caused by asymmetries in mutagenesis, gene conversion and DNA repair. Mutational biases include deletions versus insertions bias, AT to CG versus GC to AT bias, transition–transversion bias and strand asymmetries.
Speciation and
Wolbachia
Authors: Karr Timothy L , Ballard Bill
Published: September 2006

This article has sections titled

What
Wolbachia
is

What
Wolbachia
Does to Its Host

Wolbachia
– a Reproductive Parasite of Arthropods

Models for
CI

Theory of Coevolution of
Wolbachia
and Host Insect

Likely (Theoretical) Role of
Wolbachia
in Speciation

Drosophila
as a Case Study

What Defines a Strain of
Wolbachia
?
DrosophilaEvolutionary Genetics
Authors: Noor Mohamed , Akashi Hiroshi
Published: September 2006

Research inDrosophilaevolutionary genetics is narrowing the gap between phenotypic and genotypic studies because these species are excellent organisms for laboratory use.Drosophilastudies have contributed greatly to advances in evolutionary studies at the interface of ecology and genetics.
Molecular Evolution
Authors: Klein Jan
Published: September 2006

Molecular evolution is the process by which molecules of living forms diverge from one another over time. The study of molecular evolution embraces the evolution of the molecules themselves, their origins, how they change from taxon to taxon, the effects of these changes on function, and the integration of the molecules in the biochemical pathways of an organism. It also infers phylogenetic relationships and contributes to the formulation of general principles of evolution at the molecular level.
Neutrality and Selection in Molecular Evolution: Statistical Tests
Authors: Fu Yun‐Xin
Published: September 2006

Whether a locus evolves neutrally or under the influence of natural selection is of great interest in molecular evolutionary study. Statistical tests can be used to test if the observed polymorphisms in a DNA sample are consistent with the prediction of neutral evolution.
Character Displacement
Authors: Grant Peter R
Published: September 2006

Some morphological differences between closely related species living in the same environment have arisen by natural selection that has minimized competition between them.
Chordate and Vertebrate Body Plans
Authors: Jefferies Richard
Published: September 2006

The phylum Chordata is divided into: (1) Craniata (including the Vertebrata), (2) Urochordata or tunicates, and (3) Cephalochordata or lancelets, the best known of which is amphioxus (
Branchiostoma
). Each of these three subphyla differs greatly from the other two in the body plan (the broad layout of an animal and its division into major anatomical regions such as head, trunk or tail) of its extant members. The longitudinal extent of the notochord is crucial in this respect.
Vertebrate Metabolism in Extreme Conditions
Authors: Jones James H
Published: September 2006

Vertebrates in desert, high altitude and marine environments face physiological challenges caused by temperature, water and pressure. They have therefore evolved physiological strategies and adaptations in order to survive.
Thermoregulation in Vertebrates
Authors: Speakman John R
Published: September 2006

Body temperature is one of the most important factors influencing animal function. Vertebrate animals generally regulate their body temperatures within quite narrow limits, but use different mechanisms to achieve this stability. In some circumstances, maintaining a high stable body temperature is not possible and several vertebrate groups have involved adaptive responses, such as torpor and hibernation, to overcome these problems.
Gas Transfer in Vertebrates
Authors: Truchot Jean‐Paul
Published: September 2006

Oxygen supply to, and carbon dioxide removal from, vertebrate respiring tissues take place through a set of serially arranged anatomical compartments, either by molecular diffusion or by mass convection via carrier fluids. Respiratory organs are designed in such a way as to optimize the efficiency of gas transfer according to particular constraints set out by ambient media and/or animal physiology.
Sex Hormones in Vertebrates
Authors: Bentley PJ
Published: September 2006

The dimorphic development of male and female vertebrates, including humans, and the physiological processes involved in their respective contributions to reproduction are coordinated by a variety of hormones. They include specific sex hormones which are predominantly produced by the ovaries and testes. They are also called gonadal steroid hormones, the principal ones being classified as oestrogens, androgens and progestogens (progestins).
Reproduction in Vertebrates: Overview
Authors: Finn Colin A
Published: September 2006

Vertebrates comprise a diverse collection of animal species. In their reproductive processes they show evolutionary progression from simple shedding of the gametes into the water, as seen in cyclostomes, to the birth of living young seen in most mammals.
Musculoskeletal System – Overview
Authors: Lieberman Daniel E
Published: September 2006

The musculoskeletal system comprises a number of specialized connective tissues, including bone, cartilage, muscle, ligament and tendon, whose major functions are to provide rigid support for the body, protect organs and other tissues, and to generate and enable controlled movement. Most movement is created by muscular contractions which act upon bones that move (some slide) at joints. Variations in joint structure constrain the range and type of movement that can occur at each joint.
Tetrapod Climbing and Swinging
Authors: Bertram John
Published: September 2006

The diverse groups of climbing animals encounter many unique physical challenges as they move around. Many of the common solutions involve very specialized anatomy to overcome these problems.