bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunology of Invertebrates: Humoral
Authors: Zänker Kurt S 
Published: June 2010

Abstract

Phagocytosis in unicellular animals represents a ubiquitous form of immune defence. Multicellular invertebrates possess phagocytotic cells and have evolved more complex functions attributed to immune defence, for example opsonisation, encapsulation, melanisation and specialised humoral immune response. Thus, all animals possess innate, natural, nonspecific, nonanticipatory, nonclonal, germline host defence functions. Pathogen‐associated molecular pattern (PAMPs) are conserved structures or motifs of microbes and are recognised by different families of pattern recognition proteins (Toll pathway, cascade of
serine proteases
,
agglutinins
/
lectins
), thereby activating an immunological response of the host. This enhanced specificity conveys a special form of memory in invertebrates. At the humoral response antimicrobial proteins, iron‐binding proteins,
phenoloxidase
,
matrix metalloproteases
, small effector molecules (reactive oxygen species and nitrogen intermediates) and complement‐like molecules are synthesised by immuno‐/haemocytes and fat body and released at infectious tissue and into the haemolymph. The communication between and regulation of the humoral immune response is orchestrated by cytokine‐like molecules and protease inhibitors, which also bridge as regulator molecules the humoral with the cellular defence system.

Key Concepts:

The phylogenetically ancient innate response attacks infectious DNA/RNA carriers from the moment of first contact and is the fundamental defensive weapon of multicellular organisms.

The process of phagocytosis in unicellular organisms represents the most ancient immune defence, followed by opsonisation, encapsulation and melanisation in metazoa.

The pathogen‐associated molecular patterns (PAMPs) are conserved structures and motifs of microbes, and, when recognised by pattern recognition receptors (PRRs), initiate an immune response of the host.

The nonself‐recognition of PAMPs by PRRs is already a special form of memory of invertebrate hosts.

The immune surveillance concept based on self‐ and nonself‐discrimination/recognition is extended and fine‐tuned by the danger model.

The important key genes and pathways of vertebrate immunity have much earlier origins and are expressed in some of the simplest of true animals.

The invertebrate immunity is an example to understand a Darwinian principle of evolution that complex systems develop through small sequential steps.
Lipid Bilayers
Authors: Raudino Antonio , Sarpietro Maria Grazia 
Published: June 2010

Abstract

Lipid bilayer is the most simple model of the cell membrane which retains many of its properties even in the absence of proteins. Its formation, structure and properties rely on a subtle combination of different physical forces as well as on the unique chemical nature of the lipid molecules constituted by a polar head covalently linked to a long hydrophobic hydrocarbon chain. Here we present a brief summary of the chemical structure and related geometry of the most common lipids together with a short description of the relevant collective properties of the resulting supramolecular aggregate. The key role played by the solvent is emphasised. Among the key features of the lipid bilayer, we mention the order–disorder phase transition of the hydrophobic tails, the lateral phase separation of the bilayer's components into patches of different composition, the associated variations of the geometrical and transport properties and lastly the intricate interplay of different attractive and repulsive forces between bilayers brought at close distance.

Key Concepts:

Lipid bilayers provide the fundamental architecture of biological membranes.

Lipid molecules contain a polar head linked to a hydrophobic tail.

Formation of the lipid bilayer arises from the synergistic hydrophobic effect and maximum exposure of the polar heads to water.

The bilayer forms a pseudo two‐dimensional fluid that may undergo solid–liquid transitions similar to those of common fluids.

The lipid (or lipid–protein) components are not ideally mixed. Often domains with different composition spontaneously appear.

Compositional heterogeneity along the membrane plane or perpendicular to it may induce profound modification of the bilayer's shape.

Adjacent bilayers interact through a combination of attractive and repulsive forces.
Heart Development: Gene Control
Authors: Krieg Paul A 
Published: June 2010

Abstract

All creatures from flies to humans possess a heart‐like contractile organ responsible for movement of fluid through the body. Molecular studies have revealed a remarkable degree of evolutionary conservation in the genetic pathways underlying heart development. In

Drosophila

, the transcription regulatory proteins
TINMAN
,
PANNIER
,
MEF2
, plus members of the
TBX
and
HAND
families are required for regulation of heart muscle differentiation and correct morphogenesis of the heart. Expression of the cardiac transcription factors is regulated by growth factor signalling from adjacent tissues. In vertebrates, members of precisely the same transcription factor families are required for heart development and their expression is also subject to growth factor regulation. One major difference is that higher organisms usually express several members of each protein family, leading to at least partial functional redundancy. In both flies and mammals, several distinct transcription regulatory proteins interact both genetically and physically to precisely regulate transcription of the structural, morphological and physiological genes required for establishment of correct heart structure and function.

Key Concepts:

The transcription regulatory system required for development of the heart involves members of several distinct transcription factor families.

Interactions between a number of distinct transcription factors are essential for gene regulatory function.

Genetic regulation of heart development is evolutionarily conserved.
Bacteriophages: Lipid‐containing
Authors: Oksanen Hanna M , Poranen Minna M , Bamford Dennis H 
Published: June 2010

AbstractViruses exhibit vast diversity in their form and function and are by far the most numerous (estimates 1030–1032) organisms on earth. The largest group among viruses is bacteriophages, the viruses that infect bacteria, with over 5000 identified members. Majority of the phages are composed of protein and nucleic acid with a head–tail morphology. Polyhedral, filamentous or pleomorphic phages comprise only less than 4% of the described bacteriophages, and a minority of these have lipid constituents in addition to nucleic acid and protein. These lipid‐containing bacteriophages form a diverse group of viruses and they are classified in four virus familiesCorticoviridae,Cystoviridae,PlasmaviridaeandTectiviridae. The lipids can be either as the outermost layer of the virion or they can locate internally enclosed within the virus capsid. In both cases, the viral membranes are involved in cell entry processes.Key Concepts:The lipid‐containing bacteriophages are a diverse group of bacterial viruses.The lipid‐containing bacteriophages are sensitive to organic solvents and detergents.Lipids in the viral membrane have a bilayer structure.The virion proteins are all virus specific, but lipids are derived from host cytoplasmic membrane.During virus morphogenesis, the virus‐specific proteins exclude host proteins during formation of the viral membrane.The viral protein‐rich membranes have an essential role during entry mediating the translocation of the genome across the host cell envelopes.
Cells of the Immune System
Authors: Todd Ian 
Published: June 2010

Abstract

The immune system includes a range of cell types with different roles in defending the body against infection. Many of these cells arise in the bone marrow, circulate in the blood and can migrate into solid tissues. Immune responses involve interactions between some of these cells and/or their secreted products. B and T lymphocytes specifically react to microbial antigens: activated B lymphocytes secrete antigen‐binding antibodies, and subpopulations of T lymphocytes possess regulatory or cytotoxic functions. Natural killer cells are also cytotoxic cells of the lymphoid lineage, but they do not possess properties of antigen recognition. Different types of dendritic cells present antigens to T and B lymphocytes. Blood monocytes give rise to tissue macrophages that are phagocytes, as are circulating neutrophils, which are the most plentiful type of granulocyte. Other circulating granulocytes are eosinophils that secrete toxic mediators, and basophils that, in common with tissue mast cells, are important sources of inflammatory mediators. Other cells contribute to immune and inflammatory responses, including endothelial cells, erythrocytes and platelets.

Key Concepts:

A variety of cell types are important components of the immune system.

B and T lymphocytes specifically recognise antigens and are responsible for adaptive (acquired) immunity.

B lymphocytes recognise native (unprocessed) antigens via surface immunoglobulins and produce secreted immunoglobulins (antibodies).

T lymphocytes recognise processed antigens (usually peptides) associated with MHC proteins expressed on the surface of antigen‐presenting cells.

Different T lymphocyte subpopulations have helper, cytotoxic or regulatory functions.

Natural killer (NK) cells are lymphoid cells that lack antigen‐specific receptors, but mediate cytotoxic activity against infected or malignant cells.

Dendritic cells are potent antigen‐presenting cells involved in the activation of T lymphocytes, whereas follicular dendritic cells present antibody‐associated antigens to B lymphocytes.

Monocytes are circulating blood cells that give rise to tissue macrophages with phagocytic and antigen presentation functions.

Granulocytes circulate in the blood, migrate into tissues, and include phagocytic neutrophils and eosinophils that secrete toxic mediators, and basophils that release inflammatory mediators; mast cells are tissue cells with similar properties to basophils.

A variety of other cell types contribute to the generation and regulation of immune and inflammatory responses, including endothelial cells, erythrocytes and platelets.
RNA
Structure
Authors: Chen Yu , Varani Gabriele 
Published: June 2010

Abstract

Ribonucleic acid
(RNA) molecules perform their function in living cells by adopting specific and highly complex 3‐dimensional structures. Like proteins, RNA structure can be described in terms of its primary (sequence), secondary (hairpins, bulges and internal loops), tertiary (A‐minor motif, 3‐way junction, pseudoknot, etc.) and quaternary structure (supermolecular organisation). Watson–Crick base pairs as well as other noncanonical base interactions are the basic building blocks of RNA secondary and tertiary structures. Metal ions are essential for the stabilisation of RNA tertiary structures and for catalytic function. In the past decade, there has been a tremendous advance in RNA structure determination, with the successful determination of the ribosome structures, as well as many other folded large RNAs. These studies have given us a unique new opportunity to understand the structure–function relationship of RNA molecules to an unprecedented level of insight.

Key Concepts:

Double helical tracts separated by single‐stranded nucleotides represent the basic building block of RNA structure.

Hairpins (or stem–loops) are the most common element of RNA secondary structure.

RNA secondary structure can generally be predicted successfully from sequence analysis and thermodynamic calculation.

RNA secondary structure is generally more stable than its tertiary structure.

RNA three‐dimensional structures form by joining together the different secondary structure elements through the formation of long‐range tertiary interactions.

Coaxial stacking between double‐stranded helices at junctions where helices come together is a major determinant of higher order RNA tertiary structure.

Multivalent ions are often important for thermodynamic stabilisation and catalytic activities of RNA tertiary structures.
Fibrinogen and Fibrin
Authors: Doolittle Russell F 
Published: June 2010

Abstract

Fibrinogen
is a soluble plasma protein that is converted to polymeric
fibrin
in response to damage to the vascular system. The clotting process is initiated when platelets aggregate at the wound site. Their disruption releases biologically active amines and a proteolytic cascade follows which culminates in the conversion of
fibrinogen
to
fibrin
. The
fibrin
polymer forms the matrix of the tangle of cellular and molecular substances called the blood clot. Atomic‐level details are now in hand for many of the interactions that hold
fibrin
units together, although some aspects have yet to be resolved. Of necessity,
fibrin
clots need to be dismantled when they are no longer needed, an operation largely accomplished by the proteolytic enzyme
plasmin
. Various regulatory phenomena are involved in maintaining the balance between intravascular fluidity and clots that prevent blood loss. A variety of hereditary conditions, including mutant
fibrinogens
, can predispose individuals to either thrombosis or bleeding.

Key concepts:

The underlying fabric of blood clots is a protein polymer called fibrin.

Fibrin clots are formed in response to injuries to any part of the vascular system.

The conversion of soluble fibrinogen molecules to insoluble fibrin depends on thrombin generated from prothrombin.
Plant Chloroplasts and Other Plastids
Authors: Finkemeier Iris , Leister Dario 
Published: June 2010

Abstract

Plastids are a group of organelles that are characteristic of plant cells. They have derived in an endosymbiotic event from a cyanobacterial ancestor and still exhibit many prokaryotic features. Plastids are able to perform many specialised functions that are essential for plant growth and development, such as photosynthesis, nitrate and sulfate assimilation, the synthesis of amino acids and of fatty acids, storage of carbohydrates and lipids or the formation of colours in some fruits and flowers. To accomplish this, their membrane systems exert specialised transport functions, including the import and sorting of proteins and the exchange of metabolites in case of the two envelope membranes, as well as proton and electron transport in the case of the thylakoid membranes of chloroplasts. Moreover, plastids communicate with the nucleus by retrograde signalling to adjust the expression of nuclear genes according to the metabolic and developmental state of the organelle.

Key Concepts:

Plastids are of prokaryotic origin.

Several forms of plastids exist with different functions and composition.

Chloroplasts, the photosynthetically active plastids, are bounded like the other flowering plant plastids by a double membrane, but contain in addition the chlorophyll‐containing thylakoid membrane system, the site of photosynthesis.

Plastids are essential for the assimilation of nitrate and sulfate, as well as for the synthesis of aromatic compounds.

In contrast to animals, the major site of fatty acid biosynthesis in plants is within the plastid.

Plastids import most of their several thousand different proteins because the corresponding genes are located in the nucleus.

Various metabolites are imported in or exported from plastids through specific translocators within the envelope.

Plastids communicate with the nucleus by as yet unknown messenger molecules.
Tropism
Authors: Morita Miyo Terao , Tasaka Masao 
Published: June 2010

Abstract

Higher plants spend their sedentary lives at the site of their germination. Antithetically, the movement of plant organs has attracted a lot of attention. Tropism is a form of plant movement that has been studied for nearly two centuries. Conceptually, the tropic response in higher plants can be regarded as a sequential process comprising stimulus reception, conversion of the environmental signal to a biochemical one (signal transduction), transmission of the signal to the responsive tissues and organ bending. These steps are not necessarily distinct and can be continuous and overlapping. Our understanding of the genetic and molecular aspects of the mechanisms underlying this process has gradually grown during the past two decades, largely based on studies on the model plant,

Arabidopsis

. The mechanisms of tropism, with a particular focus on phototropism and gravitropism, are introduced.

Key Concepts:

Plant organs can show several types of movement, although plants have sedentary lives.

Tropism is a directional movement that is strongly related to the direction of stimulus.

Plant organs can sense various vectorial stimuli such as light, gravity, moisture and touch.

In the case of gravitropism and hydrotropism, sensing cells has been clarified.

In the case of phototropism, it is unlikely whether specific sensing cells exist but likely that a lot of cells sense the light signal and exhibit coordinated growth response in the organ.

The photoreceptors for phototropism have been identified.

Auxin, one of plant hormones, is vital not only for regulation of photo‐ and gravitropism, but also for general plant growth and development.

In the case of gravitropism and phototropism, auxin is unevenly distributed within the organ after perception of directional stimulus, resulting in organ bending.
Genetic Susceptibility to Autoimmune Disorders
Authors: Lauwerys Bernard R 
Published: June 2010

Abstract

Susceptibility to autoimmune disorders results from the interaction of multiple genetic variations that regulate the threshold of autoreactivity. Alleles of susceptibility to autoimmune diseases are frequent in the general population, when considered individually. However, if several of them (probably a few dozens) are combined in a single individual, a putative threshold is reached, beyond which gene interactions lead to pathological manifestations.

Genome‐wide association studies (GWAS) have identified numerous genetic variations, in particular single nucleotide polymorphisms (SNPs), to be significantly enriched in patients with autoimmune disorders. Strikingly, many of them (e.g. in the

PTPN22

,

STAT4

,

IRF5

and

MHC

genes) are associated with several conditions, thereby indicating that common mechanisms can lead to loss of tolerance for self‐antigens.

The identification of new genes of susceptibility to autoimmune disorders has opened large avenues of research about their role in (thus far unknown) pathogenic pathways and the possibility to modulate their contribution into the generation or amplification of autoimmune mechanisms.

Key Concepts:

Genetic susceptibility to autoimmune disorders is polygenic.

Genetic studies in autoimmunity can be biased by numerous confounding factors.

Genes of susceptibility can be categorised in three theoretical functional pathways: loss of tolerance for self‐antigens, amplification of the autoimmune response and target‐organ sensitivity.
Industry‐wide medical surveillance of California flavor manufacturing workers: Cross‐sectional results
Authors: Kim Thomas J. , Materna Barbara L. , Prudhomme Janice C. , Fedan Kathleen B. , Enright Paul L. , Sahakian Nancy M. , Windham Gayle C. , Kreiss Kathleen 
Published: June 2010

AbstractBackgroundTwo cases of bronchiolitis obliterans in flavor manufacturing workers prompted California health and labor agencies to initiate industry‐wide surveillance.MethodsCompanies' physicians submitted cross‐sectional questionnaire and spirometry data for 467 workers in 16 workplaces. We compared prevalence ratios of respiratory symptoms, diagnoses, and abnormal spirometry to a general population sample. We calculated odds ratios for risk factors for spirometric obstructive abnormality.ResultsFlavoring workers were 2.7 times more likely than the general population to have severe airways obstruction. Risk factors identified for 18 cases with obstruction from six companies included younger age, Hispanic ethnicity, liquid and powder production work, greater company diacetyl usage, and having a coworker with obstruction. Severity of obstruction was related to tenure. At least 12 workers had probable occupational fixed airways obstruction.ConclusionsThe flavoring industry risk of severe lung disease justifies lowering flavoring exposures and medical screening for secondary prevention until worker safety is demonstrated. Am. J. Ind. Med. 53:857–865, 2010. © 2010 Wiley‐Liss, Inc.
Brief communication: Mass spectroscopic characterization of tetracycline in the skeletal remains of an ancient population from Sudanese Nubia 350–550 CE
Authors: Nelson Mark L. , Dinardo Andrew , Hochberg Jeffery , Armelagos George J. 
Published: June 2010

AbstractHistological evidence of tetracycline use has been reported in an ancient X‐Group population (350–550 CE) from Sudanese Nubia (Bassett et al., 1980). When bone samples were examined by fluorescent microscopy under UV light at 490 Å yellow–green fluorophore deposition bands, similar to those produced by tetracycline, were observed, suggesting significant exposure of the population to the antibiotic. These reports were met skeptically with claims that the fluorescence was the result of postmortem taphonomic infiltration of bacteria and fungi. Herein, we report the acid extraction and mass spectroscopic characterization of the antibiotic tetracycline from these samples. The bone samples were demineralized in anhydrous hydrogen fluoride which dissolved the bone‐complexed tetracycline, followed by isolation by solid phase extraction on reverse‐phase media. Chemical characterization by high pressure liquid chromatography mass‐spectroscopic procedures showed that the retention times and mass spectra of the bone extract were identical to tetracycline when treated similarly. These results indicate that a natural product tetracycline was detectable within the sampled bone and was converted to the acid‐stable form, anhydrotetracycline, with a mass + H of 427.1 amu. Our findings show that the bone sampled is labeled by the antibiotic tetracycline, and that the NAX population ingested and were exposed to tetracycline‐containing materials in their dietary regime. Am J Phys Anthropol 143:151–154, 2010. © 2010 Wiley‐Liss, Inc.
Brief communication: Additional cases of maxillary canine‐first premolar transposition in several prehistoric skeletal assemblages from the Santa Barbara Channel Islands of California
Authors: Sholts Sabrina B. , Clement Anna F. , Wärmländer Sebastian K.T.S. 
Published: June 2010

AbstractThis article identifies and discusses seven new cases of complete maxillary canine‐premolar transposition in ancient populations from the Santa Barbara Channel region of California. A high frequency of this tooth transposition has been previously documented within a single prehistoric cemetery on one of the Channel Islands. A total of 966 crania representing 30 local sites and about 7,000 years of human occupation were examined, revealing an abnormally high prevalence of this transposition trait among islanders during the Early period of southern California prehistory (∼5500–600 B.C.). One of the affected crania is from a cemetery more than 7,000‐years‐old and constitutes the earliest case of tooth transposition in humans so far reported. The results are consistent with findings by other studies that have indicated inbreeding among the early Channel Islands groups. Together with the normal transposition rates among mainland populations, the decreasing prevalence of maxillary canine‐first premolar transposition among island populations across the Holocene suggests that inbreeding on the northern Channel Islands had all but ceased by the end of the first millennium B.C., most likely as a result of increased cross‐channel migration and interaction. Am J Phys Anthropol 143:155–160, 2010. © 2010 Wiley‐Liss, Inc.