bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cleavage and Gastrulation in Avian Embryos
Authors: Stern Claudio D 
Published: December 2009

AbstractAvian embryos differ from those of other vertebrates in several respects – among them, they have a large mass of yolk, the cells initially divide from the centre of a disk with cleavage planes that open into the yolk, and the embryo has great ability to regulate until very late stages of development. After approximately 20 000 cells have been generated, gastrulation begins. This process generates the primitive streak which defines bilateral symmetry, and through which cells from the superficial layer (epiblast) ingress to generate two new layers of embryonic cells (mesoderm and endoderm). This period of development starts to define the three axes of the future embryo (head–tail, dorsoventral and left–right), and it is at this time that many cell fates start to be fixed.Key concepts:Avian embryos cleave meroblastically: the cleavage planes are initially open to the yolk and generate a disc with smaller cells in the middle and larger, yolky cells outside.Gastrulation is the process by which the embryo generates three germ layers: ectoderm, mesoderm and endoderm. It involves massive cell movements as well as specification of cell fates through differential gene expression.As cells move around the embryo, they change their patterns of gene expression according to their current position. Therefore during early development, gene expression marks cell states rather than cell fates.The mechanisms of early development are largely conserved between different vertebrate classes but there are also some differences.Amniote (reptiles, birds and mammals) embryos have a unique capacity toregulate, meaning that when an embryo is cut into half or smaller pieces each piece can generate a whole embryo. Embryos retain this ability right up to the start of gastrulation and this is probably one of the processes responsible for generating identical twins.Neural induction subdivides the ectoderm into neural (future nervous system) and non‐neural (future skin and sensory organs in the head) territories. Neural‐inducing signals in avian embryos arise from the ‘organizer’, Hensen's node.The final head–tail axis of the embryo does not correspond to the axis of the primitive streak (which correlates better with axial and lateral fates). Mesodermal cells that will occupy more cranial positions emerge earlier from the streak than those that will end up in the trunk and tail. After gastrulation, the embryo has mechanisms that convert ‘time’ information into ‘positional identity’.
Schistosomiasis and Other Trematode Infections
Authors: Vennervald Birgitte J , Johansen Maria V 
Published: December 2009

Abstract

Trematodes, including schistosomes, are parasitic flatworms (flukes) infecting both humans and animals. Various freshwater snails are intermediate hosts. Human water contact is a key element in schistosomiasis transmission. Infection takes place when cercariae penetrate intact skin exposed to infested water. For all other trematodes, humans become infected by ingestion of metacercariae in crustacea, fish or plants, the second intermediate host, hence the term foodborne trematodes. Most of the trematodes are zoonotic and infect a wide range of domestic and wild animals as well as man. Based on the location of the adult worms, flukes can be grouped as blood (schistosomes), liver, lung or intestinal flukes. Infections can lead to serious diseases and are of economic importance owing to the high number of infections worldwide. Control strategies should include treatment of affected populations to reduce the burden of disease, health education and effective control of animal reservoir hosts.

Key concepts:

Schistosmiasis affects the general health and well being of millions of people.

Integration of schistosomiasis control measures into existing public health services are vital for long‐term success.

Agricultural development projects and irrigation can increase the risk of schistosomiasis transmission.

Domestic animals play an important role in the transmission of liver and intestinal trematodes.

Control of foodborne zoonotic trematodes requires effective control of the reservoir hosts.

Health education is an essential element in control of foodborne zoonotic trematodes.
Vesicle Transport Assay
Authors: Wöllert Torsten , Langford George M 
Published: December 2009

Abstract

Eukaryotic cells contain actin filaments and microtubules that function as cytoplasmic filaments for vesicle transport. The study of vesicle transport on these filaments

in vitro

advanced rapidly when vesicle transport assays were developed. High‐resolution multimode video‐enhanced microscopy is the method used for such assays to detect vesicles as small as 100 nm in diameter and microtubules 25 nm in diameter. Vesicle transport is recorded in real time on high‐capacity digital storage media. Motion analysis is performed to quantify different parameters of vesicle movement along cytoplasmic filaments including velocity, distances travelled and straightness of path.

In vitro

vesicle transport assays proved highly successful and enabled the identification of important factors that are essential for regulation of intracellular transport.

Key concepts

The cytoskeleton contains actin filaments and microtubules, both of which serve as tracks for vesicle transport.

Vesicle transport is the directed movement of membrane vesicles on filaments of the cytoskeleton.

Microtubules function as intracellular tracks for transport of vesicles by two classes of motor proteins, kinesins and dyneins.

Actin filaments serve as tracks for vesicle transport by myosin motors.

Motor proteins are mechanochemical nanomachines that use the energy of adenosine triphosphate (ATP) for muscle contraction, cell motility and transport of cargo along the cytoskeleton.

The superfamily of myosin motor proteins found in eukaryotic cells is known to contain over 20 different classes.

The kinesin superfamily is subdivided into 14 classes and the family of dyneins is grouped into axonemal and cytoplasmic dyneins.

Motor protein defects are associated with diseases including Griscelli syndrome, Usher syndrome, myopathies and deafness.

Differential interference microscopy, also known as Nomarski microscopy, uses polarized light to produce contrast in unstained biological specimens.

Cell‐free extracts are important tools for cell biologists and have a variety of applications including cell cycle studies, intracellular transport mechanisms, signal transduction events and maintenance of cell architecture.
Protein Quaternary Structure: Symmetry Patterns
Authors: Stenkamp Ronald E 
Published: December 2009

Abstract

Protein molecules can assemble into larger, multisubunit oligomers that possess unique quaternary structures and biological properties. The properties of the oligomeric protein can be quite different from those of the individual subunits. The noncovalent protein–protein interactions giving rise to oligomers often result in symmetric complexes containing identical monomers in identical environments. The symmetry properties of these complexes are described, in particular with respect to the types of subunit–subunit interactions giving rise to the oligomers. Because the symmetry of the macromolecular assemblies is based on the symmetric interactions between the subunits, understanding the symmetry provides further insight into the functioning of the oligomers. Specific examples discussed include:
aspartate carbamoyltransferase
(where symmetry concepts are tied to allosteric control), multienzyme complexes (built along the lines of the Platonic polyhedra) and virus capsids (large macromolecular complexes formed making use of symmetry and quasi‐symmetry).
Protein Export from Endoplasmic Reticulum to the Cytosol:
In Vitro
Methods
Authors: Matsumura Yoshihiro , Skach William R 
Published: December 2009

Abstract

Newly synthesized proteins that fail to achieve their proper conformation in the endoplasmic reticulum (ER) are recognized by quality control machinery and degraded by the
ubiquitin
–proteasome pathway. This process is termed ER‐associated degradation (ERAD) and is implicated in a large number of inherited and acquired human diseases characterized by aberrant protein folding. Because
ubiquitin
, ubiquitination machinery and proteasomes are restricted to the cytosol and nucleus, ERAD substrates must be exported from the ER lumen and/or extracted from the ER membrane before or during degradation.

In vitro

systems that reconstitute ERAD allow detailed mechanisms of ERAD to be studied independently of ongoing protein synthesis and compensatory feedback mechanisms present in cells. Evidence indicates that retrotranslocation (or dislocation) is tightly regulated via parallel pathways that are adapted to various substrates, molecular lesions and cellular needs and stresses.

Key concepts:

The endoplasmic reticulum (ER) utilizes a stringent quality control machinery for secretory and transmembrane proteins.

Misfolded proteins are recognized by the ER quality control components and degraded by the ubiquitin–proteasome pathway.

ER‐associated degradation (ERAD) is a multistep process.

Molecular chaperones and lectin‐like proteins play key roles in recognizing misfolded proteins.

Ubiquitin ligases modify ERAD substrates by covalent attachment of ubiquitin.

Two ATPase associated with various cellular activities, p97 and the 19S proteasome subunit, facilitate retrotranslocation of ERAD substrates and delivery to the 20S proteasome.

In vitro
systems reconstitute complex ERAD processes.

Mechanistic details of ERAD are readily amenable to
in vitro
manipulation and analysis.
Genetic Discrimination
Authors: Hoy Michael 
Published: December 2009

AbstractKnowledge about the relationship between genes and health, as well as genes and behaviour, is expanding rapidly. Genetic and other predictive tests are becoming less expensive and so knowledge about individuals’ genetic backgrounds is likely to become commonplace. Although such information holds the promise of eventually being very useful in the context of improving health outcomes for individuals, it has long been recognized that this promise may be accompanied by the threat of increased genetic discrimination, most notably in insurance markets. Genetic discrimination may also arise in personal and social spheres of life. Each aspect creates different types of problems. Thus, different types of remedies or responses are in order. This article reviews the ethical and economic aspects of this new information from a variety of normative perspectives and considers the appropriateness of the sorts of regulations recently put in place to limit its adverse social implications.Key Concepts:Genetic information can lead to improved decision‐making and treatments for people's health but may also lead to discrimination in insurance markets and beyond.Many academics and members of the public believe that charging different prices to different people based on genetic test results is unfairly discriminatory.However, many insurance market analysts believe individuals at higher risk of death or higher need of health care should pay more for insurance regardless of what causes their higher risk status.Economic arguments can be made that not charging risk‐relevant prices for insurance will discourage ‘better’ risks from participating in the market for insurance and this will lead to higher overall prices for insurance.The conflicting views noted above have led to unresolved issues regarding the appropriate regulation of genetic information in the area of insurance pricing.Genetic discrimination may also increase in areas of personal or social relations where market regulations are not effective remedies.Education about genetic differences may be an appropriate alternative mechanism for dealing with genetic discrimination in the personal and social spheres.
Carrier Screening of Adolescents in Montreal
Authors: Scriver Charles R , Mitchell John J 
Published: December 2009

Abstract

A carrier screening programme for common genetic autosomal recessive diseases is described. The programme focuses on testing of adolescents in their last year of high school. The main purpose of this programme is to educate the population in high‐risk communities, to offer carrier screening of autosomal recessive diseases (Tay–Sachs and β‐thalassaemia diseases) and to provide counselling about reproductive options. The specific age range targeted allows for education and screening to occur before reproduction. This is a unique programme that was developed in conjunction with the community. Although there remains controversy regarding the screening of adolescents in other areas of the world, this programme is well accepted and has continued to flourish in our specific community for over 30 years.

Key concepts:

Genetic carrier screening programmes need education, effective counselling and support from the community to be successful.

Genetic screening of adolescents in our community is well accepted by the targeted populations.

Adolescents who obtain information through carrier testing understand their risks and later utilize this information when they consider their reproductive options.
Geneticization: Debates and Controversies
Authors: Hedgecoe Adam M 
Published: December 2009

AbstractThe term ‘geneticization’ describes a process where by there is an increasing tendency to use genetic explanations to describe differences between individuals and groups. Supporters of this position argue that the way in which genetics is described in the media and dealt with the medical profession risks increases inequality and discrimination on the basis of a belief in genetic determinism among policy‐makers and the public. While this ‘geneticization thesis’ has proved popular among social scientists and bioethicists, empirical research into the way in which people interpret media messages and how clinicians adopt genetic tests casts doubt on the simplistic, homogenous model underpinning the geneticization thesis, raising challenges to the way in which this process is researched.Key concepts:The concept of geneticization has been widely used to critique the social impact of genetic testing.Empirical research undermines claims about the ubiquity and nature of geneticization.Differing attitudes towards the use of empirical data are underlined by different approaches to the study of geneticization.
Using Magic as a Vehicle to Elucidate Attention
Authors: Raz Amir , Zigman Philip 
Published: December 2009

Abstract

Attention, the awareness and selection of elements in our physical or mental environments, is a central concept in neuroscience. Michael I Posner and colleagues have proposed a three‐network model of attention. ‘Alerting’ involves increased readiness for immanent stimuli, ‘orienting’ refers to selecting amid various stimuli; whereas ‘executive attention’ links attention to decision making, planning and other higher cognitive functions. Though ignorant of the neural mechanisms underlying human attention, magicians are skilled at exploiting human attention to achieve their effects. Recent interest in the neuroscience of magic has built bridges between the practice of magic and the study of attention. However, beyond illustrating how our attention systems can be tricked, magic can be employed in research to explore otherwise unachievable conditions. Such methods provide a unique opportunity to study atypical attention, providing important insights into the function of human attention and other key cognitive domains.

Key Concepts

Attention refers to the preparedness for and selection of particular aspects of our environment or of ideas in our mind.

Attention can be overt, that is tied to fixation, or covert, like when we attend to something we are not looking at.

There are three attentional networks – alerting, orienting and executive – each with distinct neural correlates.

Magicians exploit change blindness, inattentional blindness and choice blindness to achieve many effects.

Neuroscientists have recruited magic as a tool for uncovering the nature of many cognitive processes, most notably attention.

Pushing healthy individuals towards atypical attention – via hypnosis, deception and other methods – introduces unique experimental opportunities.

Aside from helping direct investigations of attention, magic tricks can be effectively incorporated into certain experimental designs.
Neural Control of Birdsong
Authors: Schmidt Marc F 
Published: December 2009

Abstract

Birdsong is a learned behaviour that displays a remarkable level of acoustic and temporal complexity. It is controlled by a well‐defined neural circuit, known as the song system, which receives highly processed auditory information from specialized higher‐order auditory areas. Over the past decade, sophisticated new song analysis tools coupled with the ability to record from identified neurons in adult and juvenile singing birds have revealed many fundamental insights into the neural mechanisms that underlie vocal production, storage of auditory memories and sensorimotor learning. Some of these include an understanding of how sleep drives song acquisition and how circuits homologous to the mammalian basal ganglia generate the motor variability that enables sensorimotor learning. The tractable nature of this system coupled with its shared similarities with human speech make birdsong a unique model for understanding the neural bases of vocal production and learning.

Key Concepts:

Sophisticated new methodologies in song quantification have made it possible to provide quantitative descriptions of the entire vocal imitation process in juvenile birds.

Storage of the song template likely occurs in specialized higher‐order auditory forebrain areas rather than in the song system proper.

The song system is a specialized neural circuit that is necessary for song production and sensorimotor learning.

Neurons that form part of the descending motor pathway produce short (approximately 5 ms) bursts of action potentials that are precisely time locked to specific time segment of the song.

The portion of the song system necessary for song production is organized as a recurrent pathway with structures in the thalamus and respiratory brainstem projecting back up to the forebrain.

Neural variability from the basal ganglia circuit onto RA is thought to contribute to the observed motor variability in juvenile birds and likely enables the motor exploration strategy that is critical for song learning in juveniles.

Sleep plays a critical role in vocal learning by allowing offline processing of sensory and motor information.
HPVVaccine
Authors: Inglis Stephen 
Published: December 2009

AbstractThe discovery in the early 1970s that cervical cancer was caused by infection withhuman papillomavirus(HPV) stimulated a highly successful vaccine development programme based on the use of recombinantdeoxyribonucleic acid(DNA) technology to produce virus proteins in a form that can stimulate powerful and long lasting antibody responses. The vaccines have been designed as combinations to target the HPV virus types that are responsible for most human disease. Clinical trials have shown that it is possible to prevent both genital warts and the early stages of cervical cancer through vaccination and this has led to licensure and use of HPV vaccines in many countries throughout the world. Progression from initial virus infection to development of invasive cancer is often very slow, however, and so it will be many years before the impact of the vaccine on the overall disease burden is fully understood.Key ConceptsVaccine developmentVirus‐like particlesRecombinant protein expressionImmunization against an epithelial infectionPrevention of papillomavirus‐induced disease
Caspases and Cell Death
Authors: Hernandez Lorraine D , Houde Caroline , Hoek Maarten , Butts Brent , Nicholson Donald W , Mehmet Huseyin 
Published: December 2009

Abstract

Caspases (
Cysteinyl ASPartate‐specific proteASE
) are
cysteine proteases
involved in cell death. The caspase family is comprised of 12 proteins in humans, seven in

Drosophila melanogaster

and a single protein in

Caenorhabditis elegans

. All caspases consist of three structural domains: a prodomain, a large subunit and a small subunit. The catalytically active enzymes are formed either by proteolytic cleavage of the subunits, or through a proximity‐induced activation process involving the prodomain. The cleavage site of caspase substrates is indicated by the positions P4, P3, P2 and P1. P1 is always aspartate, while amino acids in the other positions are highly variable. By cleaving over 1000 substrates in the cell, caspase activation results in the complete dismantling and ultimate death of the cell. Caspase activity can be regulated at a pharmacological level and has become a therapeutic target for the treatment of many diseases.

Key Concepts

Caspases (Cysteinyl ASPartate‐specific proteASE) are the key enzymes regulating and executing apoptosis. They include several proteases acting either at the upstream regulatory events, or in the effector phase of cell death.

Three groups of caspases have been classified and are involved either in inflammation or cell death.

Caspases cleave over 1000 proteins within the cell causing the morphological events of cell death.

Both natural (cellular, bacterial and viral) and pharmacological inhibitors of caspases have been identified offering novel therapeutic approaches to inflammatory and apoptotic pathways.
Engulfment of Apoptotic Cells and Its Physiological Roles
Authors: Hanayama Rikinari , Miyanishi Masanori , Yamaguchi Hiroshi , Suzuki Jun , Nagata Shigekazu 
Published: December 2009

Abstract

During development of animals, many cells undergo programmed cell death via apoptosis. In adult, senescent cells also undergo apoptosis and are replaced by newly generated cells. Apoptotic dying cells display an “eat‐me” signal(s) on their surface, and are recognized by macrophages and immature dendritic cells for engulfment. Phosphatidylserine, which is exposed on the cell surface in a caspase‐dependent manner, is the most likely candidate for the “eat‐me” signal. Phagocytes recognize phosphatidylserine through specific receptors or via bridging molecules that link them with the apoptotic cells. Phagocytes engulf the apoptotic cells in a Rac1‐dependent manner probably through specific portals. When apoptotic cells are not engulfed efficiently, they undergo secondary necrosis and release their cellular contents, which leads to local inflammation, production of autoantibodies, and SLE (systemic lupus erythematosus)‐type autoimmune diseases.

Key concepts:

Apoptotic cells are swiftly removed by phagocytes.

Phosphatidylserine on apoptotic cells plays an important role as an “eat‐me” signal.

Phosphatidylserine is recognized by both soluble molecules and surface receptors.

The engulfment of apoptotic cells leads to an anti‐inflammatory response by the immune system.

The inefficient removal of apoptotic cells leads to autoimmune diseases.