bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecophysiological Responses of Plants to Air Pollution
Authors: Caporn Simon JM
Published: April 2013

In industrialised and heavily populated regions of the world, air pollution has an important influence on vegetation, affecting the production, abundance and distribution of plants. The principal primary pollutants are reactive compounds of sulphur, nitrogen and hydrocarbons emitted during the combustion of fossil fuels in industry, transport and from intensive farming. Increasing in importance is the secondary pollutant ozone. The direct effect of pollutants on plants is strongly influenced by the extent of their uptake into the plant tissues. Pollution also affects soils through increasing soil acidity and altering the balance of soil nutrients affecting roots and plant nutrition. Air pollution affects plants interactions with pests and pathogens and the sensitivity of vegetation to cold and drought stress. Understanding the ecophysiological responses and mechanisms by which air pollutants affect plants helps policymakers to set guidelines for air pollution to protect vegetation, crops and ecosystems.

Key Concepts:

Fossil fuel combustion and intensive agriculture are the main sources of air pollutants, which may be transported over long distances to affect plant life on a global scale.

In developed nations, sulphur dioxide, smoke and acid rain were the main acute air pollution concerns in the past, but now ozone and reactive nitrogen may pose the greatest threats.

Pollutants are deposited to plants as dry deposition of gases and particles and wet deposition in rain and cloudwater.

Stomata and cuticle on plant's surfaces provide an important control on uptake by vascular plants.

Bryophytes and lichens are vulnerable to air pollution as they lack a protective cuticle.

Acid rain, ozone, SO
2
and other pollutants can directly injure the physiology of above ground plant tissues such as leaf gas exchange, carbon transport or flowering.

Soils are affected by increased acidity and nitrogen deposition which have long term effects on plant nutrient uptake, root system health and species competition.

Biodiversity and structure of plant communities appears to be damaged by long term nitrogen deposition.

Air pollution increases plant attack from pests and pathogens and increases vulnerability to cold and drought stress.

More understanding is needed of damage mechanisms to inform air quality guidelines to protect plants and their ecosystems.
Ecology of Vertebrate Nutrition
Authors: McWilliams Scott R
Published: April 2013

Vertebrate nutritional ecology is the study of the interrelationships between food resources in the environment and the consumptive use of these food resources by vertebrate animals. Consumptive use includes how vertebrate animals procure, digest, absorb and metabolise available foods in the environment to satisfy their requirements for health, growth and reproduction. The challenge for wild vertebrates is to satisfy their nutritional requirements in an environment that often varies in food availability and quality. Vertebrate animals have evolved a diverse and interesting suite of solutions to the problem(s) of acquiring necessary nutrients and energy in a world where food often does not want to be eaten.

Key Concepts:

Vertebrates require certain amounts of energy, protein, as well as about 38 micronutrients including 10 essential amino acids, 1–3 essential fatty acids, 13 vitamins and at least 14 essential minerals.

Energy requirements (kJ day−1) of vertebrates increase with body mass of the animal in a predictable allometric manner (slope≈0.72), although birds on average have higher energy requirements for a given body size than mammals.

Protein requirements of vertebrates depend on protein quality (i.e. amino acid composition of dietary protein) because animals require a balanced profile of essential amino acids relative to their needs so that normal rates of protein synthesis are maintained.

Vertebrate animals can grow normally on a diet without carbohydrates provided they consume adequate fats that include the few essential fatty acids.

Bill morphology in birds, and tooth and jaw structure in all other vertebrate classes are impressively diverse and provide excellent examples of evolutionary design in relation to procuring food.

The chemical breakdown of ingested food involves specific enzymes that digest each of the three major types of macronutrients: proteases for digestion of protein, carbohydrases for digestion of carbohydrates and lipases for digestion of fats.

Absorption of digested macronutrients and micronutrients by the intestine involves several processes including passive diffusion, facilitated diffusion and active transport.

Changes in specific activity of digestive enzymes and the absorption rate of digested nutrients by the intestine in response to diet changes provide strong evidence for adaptive modulation of digestive features.

The evolution of enlarged portions of the gut to house symbiotic microbes was crucial in the radiation of herbivorous vertebrates because it provided the appropriate conditions for microbial fermentation to have significant nutritional benefits.

Contemporary research is providing new insights into the importance of phenotypic plasticity and flexibility in the metabolism, physiology and behaviour of wild animals and how this influences an animal's ability to satisfy its nutritional needs in their natural environment.
Urban Ecology: Patterns of Population Growth and Ecological Effects
Authors: Zipperer Wayne C , Pickett Steward TA
Published: April 2013

Currently, over 50% of the world's population lives in urban areas. By 2050, this estimate is expected to be 70%. This urban growth, however, is not uniformly distributed around the world. The majority of it will occur in developing nations and create megacities whose populations exceed at least 10 million people. Not all urban areas, however, are growing. Some are actually losing populations because of changing economic conditions and population demographics. Whether a city is growing or losing population, governances face unique challenges with respect to infrastructural, water and transportation needs. To meet these challenges, agencies within city government are cooperating by pooling resources and removing conflicting policies, partnering with the private sector to offset costs of infrastructure, and taking new approaches to design infrastructure. By linking ecological theory with urban design, a more integrative approach to create liveable spaces, which are sustainable, can be achieved in rapidly expanding and shrinking urban areas.

Key Concepts:

Megacities and shrinking cities are our future. In the nineteenth and twentieth centuries, most of the world's population lived in rural areas. With economic shifts people moved into cities to find employment, better health services, and improved education opportunities.

Future cities represent major ecological, social and economic challenges and opportunities. Rapid urban growth creates economic incentives but can fragment, destroy or degrade existing natural ecosystems. Similarly, population losses create economic and ecological opportunities for expansion and growth.

Integrating ecological theory in urban design can create a framework for sustainable cities that are adaptive and resilient. Often, infrastructure is designed to meet engineering specifications but do not incorporate ecological functionality. By integrating ecological with the engineering, infrastructure can meet regulations at the same time enhancing the environment.
Eutrophication of Lakes and Rivers
Authors: Duncan Emily , Kleinman Peter JA , Sharpley Andrew N
Published: April 2013

Eutrophication is an ecological process, akin to aging, in which a water body is increasingly enriched with organic matter. Although the most obvious signs of eutrophication in lakes and rivers involve algal blooms and fish kills, the systemic of eutrophication, although profound, are often not as noticeable to the casual observer. Eutrophication of lakes and rivers is accelerated by nutrient pollution, one of the most pervasive water quality problems in the world. Increases in populations and intensification of land use have accelerated eutrophication of water bodies from the Great Lakes of North America, to Lake Tai of China to Lake Victoria in Africa. Because nutrients can come from many sources, point as well as nonpoint, comprehensive strategies are required to curb eutrophication. A variety of watershed programs have yielded success, but they are outnumbered by the ever‐expanding number of lakes and rivers that are undergoing eutrophication.

Key Concepts:

Eutrophication of lakes and rivers is caused primarily by inputs of phosphorus and nitrogen.

Accelerated eutrophication can render a water body unusable for many uses, from fishing to swimming to drinking water.

Point source pollution comes predominately from industrial sources and wastewater treatment plants.

Nonpoint source pollution, or diffuse pollution, derives from urban and rural land uses, ranging from lawns and golf courses to agricultural fields.

Watershed management is required to successfully control eutrophication, involving comprehensive programs that tackle the many sources of nutrients in a watershed.

Nonpoint sources of nutrients, such as soils, sediments and groundwater, are extremely difficult to combat, requiring decades to reverse.
Agricultural Production
Authors: Pimentel David
Published: April 2013

World food security is threatened because agricultural production is unable to keep up with the increasing demand for food to feed a rapidly growing human population. Soil erosion due to agricultural production occurs much faster than soil formation. Water is fundamental to food production requiring 1000 L to produce 1 kg of biomass. Plants only collect less than 0.1% of energy reaching them per year. Approximately 10 kcal of fossil energy are required to produce 1 kcal of food. Finite natural resources, such as land, water and energy, limit what most technological advances in agricultural production can accomplish. If projected human population growth comes to pass, additional malnutrition and even further starvation will occur. Severe social and political disorder will also occur because agricultural production will fail to keep pace with population growth.

Key Concepts:

Malnutrition is more than simply not enough food or even being hungry or not but whether adequate absorption of food nutrients occurs and how successfully disease and parasitic organisms compete for nutrients with the human organism they may come to inhabit.
Ecological Methods
Authors: Henderson Peter Alan
Published: April 2013

Ecological methods cover a wide range of techniques required for studies that range in scale from the individuals on a single flower head to entire ecosystems with thousands of species. Although both the scale and the questions a study is designed to answer can vary greatly, there are certain key components that are always present in a well‐designed ecological study. First, ecological studies involve setting objectives and formulating a sampling programme. Second, there is often a practical component involving measurement and sampling in the field, which frequently includes sorting, identifying and measuring the organisms retrieved. Third, there is data analysis and reporting. The results can be used to derive absolute or relative population abundance measures, construct life tables, probe population dynamics and estimate biodiversity.

Key Concepts:

Ecological methods address a wide range of scales and are concerned with the acquisition of data on individual organisms, single populations and entire ecosystems.

Ecological studies have three key components: programme planning, field data acquisition and data analysis.

Studies can be broadly classified as intensive or extensive. Extensive studies are carried out over larger areas than intensive studies and seek to obtain information on the distribution and abundance of species for conservation and management purposes. Intensive studies involve the repeated observation of a population to gain insight into demographic processes.

Sampling methods can be classified into absolute methods, which give densities per unit area of habitat and relative measures which give an index of abundance.
Dinosaur Growth: Egg to Adult
Authors: Chinsamy‐Turan Anusuya
Published: April 2013

The integrity of the microstructure of fossilised bones generally survives millions of years of fossilisation. Analysis of the preserved bone microstructure of dinosaurs permits a direct assessment of the nature and type of bone that was present in the once living animal. By comparison with the bone microstructure of living vertebrates, deductions pertaining to various aspects of the life history and biology of the dinosaur can be made. Studies of the bone microstructure of dinosaurs suggest that the growth strategies of dinosaurs varied: some dinosaurs grew rapidly and uninterruptedly, whereas others experienced periodic pauses in growth. If growth rings are present in the fossil bones of different sized individuals of a particular taxon, skeletochronology can be applied to deduce the growth trajectory for the dinosaur. Such growth curves suggest that dinosaurs had a unique growth strategy that was faster than that of extant reptiles, but not as fast as similar sized birds and mammals.

Key Concepts:

Fossilisation generally preserves the integrity of the dinosaur bone microstructure.

Bone microstructure of dinosaurs can be directly compared to extant vertebrates.

Different types of bone microstructure suggest different rates of bone deposition.

Dinosaurs have an abundance of fibro‐lamellar bone.

Many dinosaurs have an interrupted (zonal) type of bone tissue.

Changes in bone microstructure through ontogeny can be assessed.

Growth lines are assumed to be annually formed.

Skeletochronology can be applied to many dinosaur taxa to assess age.

Growth curves can be deduced for dinosaurs.

Growth curves suggest dinosaurs grew faster than similar sized reptiles, but not as fast as similar sized birds and mammals.
Evolutionary Progress: Conceptual Issues
Authors: Shanahan Timothy
Published: April 2013

Perhaps no idea has proven more controversial within evolutionary biology than the idea that evolution manifests progress. To some biologists evidence of progress in the history of life has seemed undeniable. From utterly simple beginnings have come organisms of astounding complexity and sophistication. But to others the hazy notion of evolutionary progress appears distinctly unscientific inasmuch as it is thought to require subjective value judgements that have no place in a science based squarely on empirical facts. Debates over evolutionary progress can be substantially, albeit not entirely, resolved by examining some of the assumptions underlying such debates and by attending more carefully to the definition of key concepts such as ‘direction’ and ‘improvement’. Doing so suggests that acceptance of a moderate form of evolutionary progress can accommodate evidence from the history of life while satisfying standards of scientific objectivity.

Key Concepts:

The concept of ‘progress’ has been controversial within evolutionary biology.

Resolving disagreements about evolutionary progress requires careful examination of theoretical, empirical and conceptual issues.

Evolutionary progress may be defined as intergenerational directional change embodying improvement in the properties characterising a population of biological entities.

A process has a direction over a given time interval if the value of one of its properties increases during that time interval.

Directional change, which is an observable fact, must be distinguished from directionality, that is, a tendency to change in a specific direction.

It is important to distinguish uniform, net and apex directional change.

Critics of the idea of evolutionary progress complain that ‘improvement’ is a value‐laden term that cannot be given an objective scientific definition.

Improvement in the evolutionary sense is any directional change that contributes to the solution of a problem facing biological entities in a particular environment.

A number of biologists, beginning with Darwin, have argued that evolution manifests progress in the sense defined here.

If the ability of organisms in even one lineage to cope with some problem impacting their chances for survival and reproduction has improved over some time interval, then evolutionary progress, at least in this limited sense, is a scientific fact.
History of Enzyme Chemistry
Authors: Cornish‐Bowden Athel
Published: April 2013

Enzymes have been recognized as the catalysts necessary for all physiological processes since the end of the nineteenth century. Before then their study was complicated by arguments over vitalism, which only subsided after Buchner showed that a cell‐free extract from yeast could carry out alcoholic fermentation. This led to the flowering of studies of metabolism, and with it a corresponding increase in studies of enzyme catalysis, which were no longer mainly limited to extracellular enzymes such as
pepsin
. The groundwork for kinetic studies was laid by Henri and by Michaelis and Menten, and understanding of enzyme catalysis was later strengthened when Sumner demonstrated that enzymes could be crystallized. The principal features of three‐dimensional structure became known by the 1950s, by which time hundreds of enzymes had been characterized, making it necessary to create a rational classification of reactions catalysed, the basis of the modern EC system.

Key Concepts:

Nearly all physiological processes are catalysed by proteins known as enzymes.

A few reactions are catalysed by non‐protein enzymes based on
RNA
.

Enzymes are highly specific, with all apart from degradative enzymes extremely restrictive in the reactions they catalyse.

Most enzymes are similar in amino acid sequence to their homologues in other species even between organisms that are phylogenetically very different.

Enzyme catalysis was initially studied primarily by kinetic measurements, but is now based also on three‐dimensional structural information derived from crystallography or NMR.
Prusiner, Stanley B
Authors: Anderson Warwick
Published: April 2013

The American scientist Stanley B. Prusiner received the 1997 Nobel Prize in Physiology or Medicine for his discovery of proteins whose pathogenic form is responsible for human ailments such as Creutzfeldt–Jakob disease (CJD).
Collectins
Authors: Thiel Steffen , Takahashi Kazue
Published: April 2013

Collectins are pattern‐recognition molecules of innate immunity and are involved in recognising pathogens and abnormal cells in an antibody‐independent manner. The name collectin is derived from the basic structure, consisting of a collagen‐like domain and a carbohydrate‐recognition domain (CRD), akin to lectins, which recognise sugars. The CRDs bind pathogen‐associated molecular patterns, which are chemical motifs exposed on the surface of pathogens and abnormal cells. Collectins are synthesised in many organs and some are circulating in blood, whereas others are localised to a tissue. Collectin genes are germinally present and therefore, their proteins are expressed at healthy state, affording an instant action. There are also a homologous protein family called ficolins, which are similar to collectins structurally and functionally. Mechanisms of actions include a direct opsonin activity, activation of complement pathways and coagulation, modulation of inflammation and adaptive immunity.

Key Concepts:

Collectins are molecules of innate immunity, which is the first line of host defence and is fully functional throughout the body and the life regardless of health.

Collectins are pattern‐recognition molecules, which are able to identify invading pathogens and abnormal cells and tissues.

Selected genetic mutations affect functions of collectins and are associated with reduced host defence mechanisms and developmental disorder.

Some collectins are disease modifier, as deficiency itself may cause no problem whereas it may have adverse effect depending on type of disease, infection or sterile injury.

Collectins have homology to ficolins structurally and functionally, and may share and substitute functions in host defence.
Post‐copulatory Reproductive Strategies
Authors: Snook Rhonda R , Pizzari Tommaso
Published: April 2013

In most sexually reproducing organisms females obtain sperm from multiple males. Such widespread female promiscuity prolongs the operation of sexual selection after copulation, through the competition of the ejaculates of different males over fertilisation (sperm competition) and mechanisms by which females systematically bias the outcome of sperm competition (cryptic female choice – CFC). Post‐copulatory sexual selection can either consistently favour certain male or ejaculate phenotypes or certain combinations of male and female genotypes. Sperm competition and CFC drive the evolution of a diverse range of post‐copulatory strategies resulting in differential ejaculate allocation by males and differential sperm utilisation by females. The post‐copulatory reproductive strategies of each sex have considerable impact on the fitness of the opposite sex, giving rise to an intimate process of intersexual coevolution. The concept of post‐copulatory sexual selection is therefore a powerful heuristic tool to explain variation in individual fitness and the staggering variation in sexual strategies both across and within species.

Key Concepts:

Sexual selection, or intrasexual competition for mates and fertilisation, can continue after copulation when females mate with multiple males (polyandry).

The post‐copulatory processes of sperm competition and cryptic female choice are equivalent to pre‐copulatory mate competition and female choice.

Molecular and behavioural studies have demonstrated the female multiple mating is nearly ubiquitous and therefore post‐copulatory sexual selection is a major evolutionary force.

Sperm competition occurs when the ejaculates of different males compete to fertilise the same set of eggs, and selects for male adaptations both to prevent and win such competition

A male's relative share of paternity is increased through adaptations of sperm quantity and quality, in addition to behavioural, morphological and physiological adaptations in somatic traits.

Cryptic female choice (CFC) refers to female‐driven biases in the outcome of sperm competition, which are repeatable within females. CFC and sperm competition are often difficult to distinguish because they can interact to bias sperm use.

Females have a wide variety of adaptations that mediate CFC; examples include differential sperm ejection, spermicide, and differential maternal allocation.

Patterns of CFC can either differ between different combinations of male and female genotypes, or be consistent among females sharing similar preferences.

Post‐copulatory sexual selection can foster the maintenance of polymorphism and alternative reproductive strategies within a species.

The post‐copulatory reproductive strategies of one sex can reduce the fitness of the other sex, reflecting sexual conflict over mating and fertilisation. Such conflict can fuel sexually antagonistic coevolution of post‐copulatory traits.
Acorales (Sweet Flag)
Authors: Bogner Josef
Published: April 2013

The Acorales contains only one family, the Acoraceae, with only one genus,
Acorus
, with two species. The species

Acorus calamus

and

Acorus gramineus

are both medicinally and horticulturally of importance.
Arecales (Palms)
Authors: Dransfield John
Published: April 2013

Arecales is the order of monocotyledonous angiosperms that includes the single family, Arecaceae, the palms. The family is divisible into five subfamilies, each with very distinctive morphology. Palms are economically very important, providing a huge range of products from food, clothing, construction and basketry material to medicine. They are usually instantly recognisable as palms, having distinctive morphology; in particular, the fan (palmate) or feather (pinnate) leaves are almost unique in development. The fossil record of palms extends from the middle of the late Cretaceous to the present day. Palms are largely confined to the tropics and subtropics, with a very few outliers in temperate regions. Across the tropics the distribution of subfamilies, tribes, subtribes and genera is uneven, reflecting a complex history of evolution and dispersal.

Key Concepts:

The palms are an iconic group of plants that epitomise the tropical world (Figure 1).

Palms boast the largest leaf, the longest unbranched stem and the largest and heaviest seed.

Palms are of immense economic significance.
Severe Acute Respiratory Syndrome (
SARS
)
Authors: Page Carly A , Frieman Matthew B
Published: April 2013

Severe acute respiratory syndrome (SARS) is a disease that caused significant morbidity and mortality during the outbreak in 2002–2003. In early 2003, a novel coronavirus was identified as the aetiological agent of SARS and is currently known as SARS‐CoV. This virus has since been extensively characterised and studied as a model for acute respiratory infection. SARS‐CoV utilises a number of virally encoded proteins to subvert the host immune system and establish infection. The ensuing immune dysregulation often results in prolonged, severe disease and sometimes death that does not always associate with the long‐term presence of virus. In addition to being an important respiratory virus model, SARS‐CoV is also an important model for emerging infectious diseases as it emerged from natural animal reservoirs. Here we review the epidemiology, clinical disease and virology of this disease‐causing virus.

Key Concepts:

Emerging viruses are able to jump from animals to people and cause infections.

Epidemiological controls can slow down respiratory virus epidemics.

Understanding viral pathogenesis aids in our ability to fight current and future virus outbreaks.
Ribosomes and Ribosomal Proteins: More Than Just ‘Housekeeping’
Authors: Chakraborty Anirban , Kenmochi Naoya
Published: April 2013

As the catalyst for protein synthesis, the omnipresent ribosome is essential to all organisms. In mammalian cells, the ribosome is composed of four ribosomalribonucleic acid(RNA) species and 79 differentribosomal proteins. Several hundred copies of the genes encoding the ribosomal RNAs form clusters within the human genome; by contrast, the genes encoding the ribosomal proteins are widely dispersed, although they are functionally related and coordinately expressed. Ribosome biogenesis is a tightly controlled multi‐step process that requires massive cellular energy. Over the past decade, our perception of the ribosome has changed significantly. In the past, ribosomes were considered critical for cellular survival. However, it has now become clear that defects in ribosome biogenesis cause pleiotropic effects that may manifest as specific disease conditions in humans. Ribosomal proteins, which were previously considered to play only a housekeeping role, are now known to have many extraribosomal functions, including the surveillance of ribosomal integrity.

Key Concepts:

All of the three RNA polymerases, several accessory proteins, and numerous small nucleolar RNAs act in a coordinated manner to ensure that ribosomal RNAs (rRNAs) and ribosomal proteins (RPs) are properly synthesised and assembled into a functionally active ribosome.

The numbers of rRNAs and RPs vary between eukaryotes, archaea, and bacteria; however, the functions of ribosomal components have been conserved to a substantial degree throughout evolution.

The nucleolus, a sub‐compartment of the nucleus that assembles around the rDNA clusters, is the major site of ribosome production.

In general, RPs are basic proteins and exhibit specific affinities for nucleic acids; however, four RPs have acidic pI values.

In humans, the genes encoding rRNAs are usually clustered together in multiple copies within the genome; whereas, the genes for the RPs, which are typically encoded by single genes, are scattered through out the genome.

Over the past two decades, RPs have been implicated in many cellular activities that are distinct from their primary functions in ribosome biogenesis.

The p53 tumour suppressor protein, an important component in the cellular response to a variety of stressors, monitors the fidelity of ribosome biogenesis through a surveillance mechanism that involves several RPs.

The disruption of ribosome biogenesis causes ‘nucleolar stress’ that triggers the p53‐signalling pathway, resulting in cell cycle arrest and apoptosis.

Haploinsufficiency in RP genes or mutations in genes that encode proteins essential for ribosome biogenesis can lead to a specific class of diseases in humans, called ribosomopathies, which often manifest as prominent tissue‐specific defects with associated pleiotropic anomalies.
Disability: Stigma and Discrimination
Authors: Scully Jackie Leach
Published: April 2013

Disability is connected to the contemporary life sciences in obvious and less obvious ways. A key justification for human genetic research is that it will lead to better understanding of the ‘normal’ human genome and thus of genetically based disability. However, there is abundant evidence that people with physical and mental impairments remain stigmatised, and the potential for science to increase the stigma of disability demands a critical examination of our beliefs about disability, normality and diversity. Where the medical model of disability sees disability as originating in the deviation of an individual from a biological or physiological norm, social models see it generated by the interaction of an anomalous body with the physical and attitudinal constraints of society. These are very different approaches to the role of biology in disability. There is concern that the biomedical model today dominates to the extent of excluding other useful approaches to disability. ‘Genetic discrimination’, not all of which can be eliminated by legislation, remains a risk to people with genetically based disabilities.

Key Concepts:

The potential for advances in genetic medicine to prevent disability provides a key justification for genetic research.

There is abundant empirical evidence that people with physical and mental impairments remain stigmatised and discriminated against around the world.

The focus on disability as a person's difference from normality is reinforced by the ‘medical model’ of disability. Within this framework, disability is seen as a nominative pathology.

Alternative models of disability place less emphasis on the individual's ‘problematic body’. For example, in the strong social model, what defines disabled people as a group is the collective of oppression or exclusion from society.

There is concern that the biomedical approach to disability, and genetic models in particular, could reinforce the stigma attached to disability.

There is a risk of ‘genetic discrimination’ – discrimination directed against people with particular genotypes. Some forms of genetic discrimination can be prevented by legislation, but others, such as the routine pre‐natal screening for and termination of affected pregnancies, are harder to prevent.

Some disability theorists are concerned that the stigma of disability will inevitably lead to information about the human genome is used for eugenic purposes.

The rapid accumulation of genetic information through the ‘genome revolution’ challenges us to look more critically at our beliefs about diversity and the value of different kinds of human being. This discussion should include the perspectives of disabled people.
Disability and Genetics: A Disability Critique of Pre‐natal Testing and Pre‐implantation Genetic Diagnosis (PGD)
Authors: Asch Adrienne , Barlevy Dorit
Published: April 2013

Selecting against embryos or foetuses on the basis of predicted disability reinforces the belief that disability is inimical to a worthwhile life. The disability critique of pre‐natal testing and pre‐implantation genetic diagnosis (PGD) flows from the belief that life with disability can be valuable to individuals, their families, and society. Disability should be understood as just another form of human variation. Reassessment of the crucial elements of the parent–child relationship is fundamental to create a welcoming society for persons with varying abilities. Reforms should be made to the information provided about the lives of persons with disabilities and their families in order to enhance women and couples’ informed reproductive decision‐making. Additionally, clinicians and genetics professionals need to understand that society contributes significantly to the difficulties that people with disabilities experience in attaining full participation in family and community life.

Key Concepts:

Neither PGD nor any method of pre‐natal testing can accurately indicate a potential child's quality of life.

The expressivist argument is only one type of disability critique, which focuses on the negative message that PGD or pre‐natal testing followed by selective embryo implantation or selective abortion sends to current persons living with disabilities.

The disability critique is not primarily expressivist.

Most negative facets of life with disability can be attributed to societal attitudes and practices that are open to change, and not to the medical condition itself.

Clinicians and professionals should understand that they have a role in ending discrimination against people with disabilities, much as they work to practice their professions without sexism or racism.

Disability, like sex, race, and ethnicity, is a legitimate, respectable form of human variation.

Preventing the incidence of disability is quite different from preventing the existence of persons with disability.

Research indicates that people with disabilities and their families fare relatively the same as the rest of the population.

The norms of good parenting include fostering and supporting the uniqueness of individual children, with all their mix of talents, personalities, strengths, and problems.

Information about the nonmedical facets of life with disability and connections to disability support groups need to be provided to prospective parents deciding about their reproductive future.
Disability: Western Theories
Authors: Woodin Sarah L
Published: April 2013

The theoretical underpinnings of conventional, individualistic medical conceptions of disability have in recent decades been challenged by various socio‐political approaches rooted in the collective experiences of disabled people and their organisations. Disability studies has developed both within and outside the academy primarily through an analysis of the structures and practices that marginalise disabled people in society. In recent decades theoretical approaches have become wider and among others these now encompass materialism, cultural studies, poststructuralism, feminism and phenomenology. Recent debates have centred on the body, the degree to which it should be a focus for social investigation and how it should be theorised. All of this has significant implications for proponents of genetic interventions as solutions to the problem of disability.

Key Concepts:

Individual, medical conceptions of disability have been challenged by socio‐political approaches.

Theoretical understandings of disablement have been given impetus by increasing evidence of social causes and implications.

Western theories of disability are characterised by increasing diversity of approaches, including materialist, cultural and poststructuralist.

Scientific understandings of disability have profound implications for life opportunities and situations of disabled people.
Disability, Human Rights and Contemporary Genetics
Authors: Scully Jackie Leach
Published: April 2013

In recent years, disabled people have been organised as a new social movement to promote their civil and human rights. At the same time, advances in genetic knowledge, especially the development of prenatal and preconception screening programmes, offer active selection against the birth of people with genetically based disability. Many disabled people are deeply concerned that selective genetic technologies bias the social context in which reproductive choices are made, implicitly questioning the right of disabled people to exist. However, it can be argued that bodily variation, even in the forms that lead to disability, should be acknowledged as part of the diversity of human embodiment. Steps in this direction can be seen in the language of human rights instruments such as the United Nations Convention on the Rights of Persons with Disabilities. Genetics can offer support for the idea that genotypic and phenotypic diversity is a natural and positive part of human societies.

Key Concepts:

During the last quarter of the twentieth century, disabled people began to be organised as a new social movement to promote their civil and human rights. As a result, many of the barriers to full participation of disabled people in society are beginning to be dismantled.

At the same time, advances in genetic knowledge have led to the growing use of technologies of genetic testing, in prenatal and preconception genetic screening programs as well as postnatal testing.

Genetics therefore holds out the promise of improving population health by reducing/eradicating genetically based disability, through selection against the birth of people with disabilities rather than through the amelioration or cure of genetic conditions.

The disability rights movement and genetics therefore represent two distinct ways of thinking about the biological meaning of disability.

Although many disabled people welcome medical and specifically genetic research, others have concerns about the way that the ready availability of genetic testing and screening changes the context in which reproductive decisions around disability are made.

Some people argue that bodily variation, even in the forms that lead to disability, should be acknowledged as part of the diversity of human embodiment.

Genetics offers some support for the idea that genotypic and phenotypic diversity is a natural part of biological populations and of human societies.

A number of recent legal instruments, including the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD), seek to protect the human rights of disabled people. Nevertheless, within the disability community there is concern that selective genetic technologies challenge the fundamental right of disabled people to exist.

Issues raised by the debate on variation and genetics will become increasingly important for nondisabled people as well, as the genetic factors that play a role in both normal variations and behaviours and common diseases are uncovered.
Twin Studies
Authors: Trumbetta Susan L
Published: April 2013

Twin studies provide useful tools for genetic and epigenetic research and also for studying the effects of nongenetic variables while controlling for genetic variation. Classic twin studies compare the phenotypic similarity of monozygotic to dizygotic twin pairs sampled from a population in order to estimate the relative influences of genetic and environmental factors on that phenotype in that population. Twin similarities may be of genetic or environmental origin; in twins reared apart, we see genetically influenced similarities emerge in very different environments. Phenotypically discordant monozygotic twins may reveal nonshared, nongenetic sources of influence on the development of that phenotype. Virtual twins, like adoptees, are biologically unrelated, and can teach us how children's rearing environments may either similarly or differentially affect their development, while holding age and cohort constant. Children‐of‐twins designs can help us detect gene‐correlated environments and distinguish between genetic and cultural factors in the transmission of complex phenotypes.

Key Concepts:

Twin studies can be used to explore a range of questions, from genetic variation in a trait in a population to the effects of specific epigenetic changes on gene expression to questions in evolutionary psychology.

Monozygotic (MZ) twins, also known as identical twins, typically share 100% of their genome and dizygotic (DZ) twins, also known as fraternal twins, share, on average, 50% of their genome. Classic twin studies use this information to estimate the relative proportions of genetic and environmental influence on a given phenotype in a given population.

Nonadditive genetic effects can make MZ twins more than twice as similar as DZ twins.

Effects of shared environments can make MZ twins less than twice as similar as DZ twins.

Studies of twins reared apart combine aspects of both twin study and adoption study designs. Remarkable similarities between MZ twins reared apart suggest a strong influence of genetic factors, and especially, of genes in specific combinations, on behavioural phenotypes.

Phenotypically discordant MZ twins may help researchers to isolate environmental and developmental contributors to, and results of, the development of that phenotype.

Phenotypically discordant MZ twins also help scientists to identify epigenetic changes that create within‐pair differences in gene expression and explain some of the within‐pair phenotypic differences.

Children‐of‐twins studies are useful in estimating the degree to which parental genotype is correlated with the offspring‐rearing environment (passive gene–environment correlation) and also in separating genetic transmission from environmental transmission (the effects of parental rearing environment).
Alzheimer Disease: Genetic and Environmental Influences
Authors: Reynolds Chandra A
Published: April 2013

Alzheimer disease (AD) is a complex, progressive neurodegenerative disease. Prevalence of AD is expected to grow substantially, although predictions may shift given future treatment interventions or higher levels of engagement in lifestyle delaying factors that may reduce risk. Several mutations have been characterised and susceptibility genes implicated as playing a role in the disorder. The apolipoprotein E (APOE) ε4 allele remains the best‐established susceptibility gene for late‐onset AD. Although a substantial proportion of the liability for AD may be accounted for by genetic factors, heterogeneity or differences in aetiology are important to consider. Environmental factors probably play a significant role, such as education, head injury and nonsteroidal anti‐inflammatory drugs (NSAIDs) use, as well as obesity, diabetes, physical activity and cognitively engaging leisure activities. The extent to which susceptibility genes interact with environmental factors may provide further clues to aetiology. Lastly, a developmental longitudinal perspective on the salience of particular risk and protective factors across the life course may illuminate etiologies and potential points of intervention.

Key Concepts:

The prevalence of Alzheimer disease (AD) will continue to rise globally, quadrupling by 2050.

The aetiology of AD is multifactorial.

Early‐onset Alzheimer disease (AD) is caused by rare mutations in three genes:
APP, PSEN1
and
PSEN2
.

Late‐onset AD is complex whereby the genetic contribution to the liability for AD may be as high as 79%.

The APOE ɛ4 allele increases the risk for late‐onset Alzheimer disease.

Genome‐wide gene association studies (GWAS) were instrumental in identifying new susceptibility genes for late‐onset AD beyond the
APOE
and
SORL1
candidates, including:
ABCA7
,
BIN1
,
CD33
,
CD2AP
,
CLU
,
CR1
,
EPHA1
,
MS4A4E/MS4A6A
and
PICALM
.

Risk and protective factors appear to play a role in AD risk, such as education, head injury, physical activity, cognitively engaging leisure activities and NSAIDs use.
Chromatin Structure and Domains
Authors: Grimaud Charlotte
Published: April 2013

In the cell nucleus,deoxyribonucleic acid(DNA) is associated with nuclear proteins called histones to form chromatin. According to the type of factors that bind it, chromatin is organised into different subdomains.

Chromatin structure is essential to compact DNA but it is also crucial for the proper development of multicellular organisms. Indeed, it is a highly organised structure through which, genetic material is modulated to regulate nuclear processes, including transcription, replication and DNA repair. It is notably regulated via reversible covalent histone modifications. These multiple modifications deposited on chromatin by different histone modifying enzymes, serve as specific recognition signal for DNA‐regulating proteins. More recently, spatial organisation of chromosomes in the nucleus has been identified as a critical feature for chromatin regulation, contributing in the fine tuning of transcription regulation, a major issue of cell differentiation and maintenance of cell identity during development.

Key Concepts:

Chromatin is a highly structured entity with an important flexibility.

The large repertoire of epigenetic modifications offers a wide range of specific molecular and cellular responses.

Together with genetic information, epigenetic marks play a critical role in the transmission of gene regulation.

Nuclear organisation of chromosomes participates in the inheritance of chromatin states.
Gel Electrophoresis
Authors: Westermeier Reiner
Published: April 2013

Gel electrophoresis is the core separation technique for genetic analysis and purification of nucleic acid fragments for further studies. In an electric field the negatively charged
deoxyribonucleic acid
(DNA) and
ribonucleic acid
(RNA) fragments migrate through a porous gel matrix toward the positive electrode, the anode. Because of the sieving effect of the gel, shorter fragments move faster than larger ones. In this way the DNA or RNA samples are separated according to their molecular sizes into distinct zones, which can be detected by specific visualisation methods. The most frequently used technique is the separation of DNA fragments in agarose gels in simple flatbed boxes combined with the detection of stained bands under ultraviolet light. Polyacrylamide gels are employed, when small fragments have to be analysed or very high resolution down to one single base pair is required. In contrast to capillary electrophoresis the substrate does not need to be prelabelled.

Key Concepts:

With gel electrophoresis very high resolution of nucleic acids can be achieved.

TBE buffer is the standard buffer for DNA and RNA gel electrophoresis.

Agarose electrophoresis is the standard method for DNA restriction fragment analysis and purification of DNA and RNA fragments.

Gel electrophoresis is better suitable for preparative applications than capillary electrophoresis.

Native polyacrylamide gel electrophoresis of amplified nucleic acid fragments is a simple and rapid method for the detection of single‐nucleotide polymorphisms.