bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidermis: Outer Cell Layer of the Plant
Authors: Glover Beverley J
Published: April 2010

The epidermis is the protective outer layer of clonally related cells covering all plant organs. It is composed of a number of specialised cell types which differentiate from the basal epidermal cell in adaptively significant frequencies and patterns. The epidermis is unique in developing solely through anticlinal divisions, generating a sheet of cells overlying the rest of the plant. This sheet is connected biochemically to the cell layers below, with information exchange occurring in both directions. The specialised cell types within the epidermis develop either through communication among themselves, or, in some cases, through communication also with the underlying cell layers. Brief descriptions of the molecular genetic control of trichomes, stomata, root hairs and petal conical‐papillate epidermal cells are provided here, along with a summary of the role of the cuticle in epidermal cell morphology.

Key Concepts:

The plant epidermis is a single layer of clonally related cells.

Plant epidermis fulfils a basic protective function, but specialised cells within the epidermis have specific roles.

The aerial epidermis originates in the shoot apical meristem, the root epidermis in the root apical meristem and the seedling epidermis arises by isolation of the outer layer during embryogenesis.

Stomatal guard cells allow gas exchange, and their patterning is controlled by cell lineage‐based developmental mechanisms.

Trichomes protect the plant from herbivores, and their patterning is controlled by cell–cell interactions.

Root hairs increase surface area for water and nutrient uptake, and are patterned according to positional signals.

The cuticle overlying the epidermis can contribute to cell shape and function.
Immunodeficiency Disorders due to Antibody Deficiency (B‐lymphocyte Disorders)
Authors: Roberts Robert L
Published: April 2010

The majority of patients with primary immunodeficiency have a defect in their ability to make sufficient quantities of specific antibodies. This lack of specific antibodies is due to the lack of B lymphocytes, defects in B‐lymphocyte function, or inability of B lymphocytes to interact with T lymphocytes. Patients born with only antibody deficiency usually appear normal at birth due to maternal antibodies that crossed the placenta. They usually start developing more infections at around six months of age when maternal antibodies have been depleted, and they cannot make their own antibodies. Treatment may include prophylactic antibodies until diagnosis is confirmed or infusion of immunoglobulin, either by intravenous route or subcutaneously. When patients have antibody deficiency plus defects in T lymphocytes, the disease is usually more severe and will be further discussed in other articles.

Key Concepts:

The most severe form of antibody deficiency, Bruton's, requires regular infusions of IVIG starting in infancy.

Common variable immunodeficiency (CVID) is often associated with autoimmune disease as well as malignancies.

Less severe forms of B‐cell deficiency may be managed with prophylactic antibiotics.

Severe combined immunodeficiency (SCID) requires stem cell transplantation for treatment.

Early diagnosis is essential in preventing long‐term disability or early death
Brain Death and the Vegetative State
Authors: Jellinger Kurt A
Published: April 2010

A brain‐dead patient is unconscious, has lost the capacity to breathe (apnoea) and requires mechanical respiration; even with full supportive treatment his heart will soon stop, usually only after a few days. The widely accepted definition of brain death (BD) equates it with death of a person and renders legally the removal of organs for transplantation. Evidence‐based criteria for the clinical diagnosis of BD and the use of confirmatory tests are available. A patient in the vegetative state is unconscious but has his eyes open and can breath on his or her own, but requires artificial feeding, automatic‐vegetative functions and some active functions of the severely damaged brain being preserved. Its diagnosis is based on repeated clinical observations and modern neuroimaging tests. Given adequate treatment persons in a vegetative state can survive for years and may recover towards the minimally conscious state or even can regain (in)complete recovery.

Key Concepts:

Brain death is the expression of irreversible loss of brain function.

Brain death is a precisely defined clinical diagnosis based on generally accepted criteria.

When the clinical diagnosis is unequivocal, no additional confirmatory tests (angiography, electroencephalography, transcranial Doppler sonography or magnetic resonance angiography) are necessary.

Causes of brain death are traumatic brain injury, cerebral haemorrhage and systemic hypoxia, and frequently associated with brain oedema and raised intracranial pressure damaging the brainstem.

The widely accepted legal definition of brain death equates it with death of a person.

Brain death diagnosis depends on adequate observation times (6–24 h or more), and its declaration has to be made by two adequately experienced physicians.

Unequivocal diagnosis of brain death generally renders legally the removal of organs for transplantation.

The vegetative state consists of continuing unconsciousness with no evidence of awareness and no possibility for communication, with the eyes open, spontaneous breathing and preserved brainstem autonomic functions.

Causes of the vegetative state are various types of severe acute brain damage (head injury, systemic hypoxia or encephalitis) or progressive brain damage (terminal states of Alzheimer or Huntington disease, demyelinating, metabolic, inflammatory diseases or severe malformations).

The diagnosis of the vegetative state depends on repeated clinical examinations and demands considerable skills; it can be supported by electroencephalography and modern neuroimaging methods showing severe drop of cerebral metabolism.

Given adequate treatment, persons in a vegetative state can survive for years and some may recover towards the minimal conscious state or may even show (in)complete recovery with various degrees of incapacity.
Cytomegalovirus Infections in Humans
Authors: Griffiths Paul D
Published: April 2010

Cytomegalovirus (CMV) is a herpesvirus that causes severe disease in the immunocompromised because virus replication is normally held in check by cell‐mediated immune responses. Patients receiving immunosuppressive drugs to allow allo‐transplantation, patients with AIDS (acquired immunodeficiency syndrome) or fetuses with immature immune responses are therefore at risk of developing CMV end‐organ disease. A high viral load is required for CMV end‐organ disease to develop. Ganciclovir is a potent inhibitor of CMV replication and can be used either for prophylaxis or for preemptive therapy (administering the drug when CMV is detected in the blood). Both of these strategies effectively control CMV end‐organ disease in transplant patients. A phase II study of a prototype CMV vaccine has recently published encouraging results, suggesting that CMV infection may ultimately be preventable by means of universal immunisation.

Key Concepts:

CMV viraemia precedes CMV end‐organ disease.

Prompt treatment of CMV viraemia prevents end‐organ disease.

The probability of end‐organ disease is nonlinear with respect to viral load.

This threshold relationship is seen also in babies with congenital CMV infection and hearing loss.

Prompt treatment of congenital CMV infection can reduce the risk of progressive hearing loss.
Thalassaemias
Authors: Weatherall David J
Published: April 2010

The thalassaemias are the commonest genetic disorders in humans and present an increasing public health problem in the tropical countries in which they occur at a high frequency. There are many different forms of thalassaemia, all resulting from mutations of the genes which are responsible for regulating the structure and synthesis of haemoglobin. These diseases are all transmitted in a Mendelian fashion; parents, who are symptomless carriers, each pass on a defective gene to a severely affected offspring. The extremely high frequency of these diseases reflects natural selection whereby symptomless carriers are more resistant to different forms of malaria. A better understanding of the genetic basis of these diseases has led to improvements in their prevention and symptomatic treatment.

Key Concepts:

The haemoglobinopathies, thalassaemia and sickle cell disease, are by far the commonest genetic disorders.

These diseases have reached their high frequency mainly due to natural selection through heterozygote protection against malaria.

Thalassaemias consist of several different disorders, each due to many different underlying mutations of the globin genes.

All the severe forms of thalassaemia show a remarkable clinical variability which reflects both genetic modifiers, adaption to anaemia and the environment.

All the different forms of thalassaemia can be identified in fetal life and hence prenatal diagnosis is possible.

A cure of thalassaemia is only possible by bone marrow transplantation when suitable donors are available.

Most serious forms of thalassaemia are amenable to symptomatic treatment with transfusion and drugs to remove excess iron.
Immunology of Invertebrates: Cellular
Authors: Smith Valerie J
Published: April 2010

Circulating (free) cells are the main mediators of immunity in invertebrates, carrying out the phagocytic, encapsulating and microbicidal responses that enable these animals to protect themselves against infection without a specific adaptive immune system. The cells are specialised for these functions, with division of labour between types. In general, immune cell diversity tends to increase with body complexity and life histories but common to the majority of species, however, are phagocytic and granular cell types that synthesise and store bioactive proteins. The release of these compounds occurs by exocytosis following interaction of pattern recognition receptors and nonself motifs carried on the surface of pathogens or parasites. Cell death of one form or another appears to be inherent in immune reactivity of many invertebrates with new cells produced, at least in coelomates, by mesodermal haemopoietic tissues.

Key concepts

Immunity in invertebrates is confined to nonspecific inflammatory responses, mediated to a large extent by the circulating blood cells (haemocytes or coelomocytes) or their products.

All coelomate invertebrates contain populations of freely circulating cells dedicated to host defence, some well developed for specialist purposes.

There are no true vertebrate‐type lymphocytes and no long‐term, highly specific immune memory in invertebrates.

The main invertebrate cellular immune responses include phagocytosis, encapsulation, cytotoxicity and the synthesis and release of microbicidal agents.

These cellular reactions often involve the death of immune cells or their removal from the circulation, requiring new cells to be synthesised in the haemopoietic tissue and released into the blood.

Genomic and proteomic studies have enabled many of the proteins responsible for cellular defence in invertebrates to be identified, especially in arthropods.

Although many of the responses and pathways are ancient and highly conserved, there is great diversity in the effector molecules across the invertebrates as a whole.
Nuclear‐encoded Protein Import into Chloroplasts: Methods
Authors: Soll Jürgen , Bölter Bettina
Published: April 2010

Chloroplasts carry out essential processes, for example photosynthesis. They are derived from an endosymbiotic event, in which an ancient cyanobacterium was engulfed by an eukaryotic ancestor. During evolution, most of the genes have been transferred to the nucleus. Consequently, >98% of all plastid proteins are translated on cytosolic ribosomes and posttranslationally targeted to and imported into the organelle. Targeting is assisted by cytosolic proteins, which keep them in an import‐competent state. At the chloroplast, many proteins have to conquer the barrier of the chloroplast envelopes. This process is mediated by two complexes in the outer (Toc) and inner (Tic) envelope. Most proteins destined for inner compartments contain a cleavable
N
‐terminal transit peptide, whereas most outer envelope components insert into the membrane without such a targeting peptide. Investigation of the import of nuclear‐encoded proteins into chloroplasts is an essential field of plant science. To throw light on this very basic process many different methods have been established.

Key Concepts:

Studying the
in vitro
import behaviour of chloroplastic preproteins gives essential insight into this fundamental process.

Analysis of mutants in model organisms provides information about the
in vivo
function of proteins proposed to be involved into translocation.
Sedimentation
Authors: Maxon Laue Thomas
Published: April 2010

Sedimentation is a classic method of biochemistry that provides first‐principle hydrodynamic and thermodynamic information about the purity, size, shape, molar mass, association energy, association stoichiometry and thermodynamic nonideality of molecules in solution. The fundamental measurement in sedimentation is the concentration as a function of radial position. Any of the three optical systems provides the necessary concentration profiles, making sedimentation a versatile tool for analysing biological solutions. There are two distinct sedimentation methods: sedimentation velocity and sedimentation equilibrium. Data analysis from either method uses computer programs developed around fundamental equations. Velocity sedimentation is used to check for impurities and also to characterise molecular interactions. Equilibrium sedimentation is not used as widely, but it is used to provide first‐principle insights into intermolecular interactions such as macromolecular binding and thermodynamic nonideality.

Key concepts:

Sedimentation velocity provides information about the size and shape of molecules in solution.

Sedimentation equilibrium provides information about the interactions of macromolecules in solution.

The quaternary structure of a molecule may be determined under different solvent conditions.

Mass‐action equilibria may be characterised with respect to the stoichiometry and association energies.

Sedimentation velocity analysis is used to detect aggregates and fragments of highly purified molecules.

Thermodynamic nonideality may be characterised from sedimentation equilibrium analysis.

Analysis programs for sedimentation velocity data often use solutions of the Lamm equation.

Analysis programs for sedimentation equilibrium data are based on thermodynamic first principles.
ATP
‐binding Motifs
Authors: Matte Allan , Delbaere Louis TJ
Published: April 2010

Adenosine 5′‐triphosphate (ATP) binds to a great number of proteins to elicit a wide variety of effects, including energy production and molecular signalling. Proteins have evolved different strategies to specifically recognize ATP, utilizing different ways of binding the phosphoryl moieties as well as the adenine base. The most common, conserved sequence and structural motif for binding ATP is the Walker‐A motif, or P‐loop, found in many different protein structural families. Greater variation in the sequence of the P‐loop is being recognized, as more ATP‐binding proteins are being structurally and functionally characterized. In contrast to the P‐loop, recognition of the adenine base often makes use of conserved structural motifs of main‐chain atoms via hydrogen‐bonding interactions, or side‐chains in stacking interactions, without a definitive amino acid sequence pattern.

Key concepts:

A major class of ATP‐binding proteins are those that contain a P‐loop or Walker‐A motif.

P‐loops or glycine‐rich loops function by binding the phosphoryl groups of ATP.

Several sequence variations on the Walker‐A motif are now known and have been functionally characterized.

The Walker‐B motif contains a conserved acidic residue (Glu/Asp) that functions to bind directly or indirectly a metal ion important in catalysis.

Adenine‐binding does not occur through specific sequence motifs, but rather uses a conserved pattern of polar and nonpolar interactions within a structural motif.

Both main‐chain hydrogen bonding and aromatic residue stacking contribute to adenine‐binding by proteins.
Genetic Counselling: Psychological Issues
Authors: Biesecker Barbara B
Published: April 2010

The goals of genetic counselling vary according to the setting in which clients are seen, from prenatal to adult. Yet an important universal goal of genetic counselling is to address the psychological impact of a genetic diagnosis, risk or test result. Clients experience a range of genetic conditions and risks that may elicit grief, conflict, sadness, relief, guilt, uncertainty and ambivalence. The specific needs of genetic counselling clients are shaped by the degree of health threat they perceive, and by their personality traits, background, resources and prior experiences. Characteristics of the condition coupled with perceptions of its burden contribute to the quality of life experienced by clients. How well genetic counselling meets clients’ needs in enhancing quality of life is determined by the expert skills of counsellors to assist clients in using their own psychological assets to adapt to their circumstances.

Key concepts

Genetic counselling aims to help clients adapt to living with a genetic condition or risk.

Genetic counselling clients’ experience genetic conditions or risk according to their own illness perceptions and this predicts their overall quality of life.
DNA
Methylation in Development
Authors: Rutledge Charlotte E , Lees‐Murdock Diane J , Walsh Colum P
Published: April 2010

DNA (
deoxyribonucleic acid
) methylation is an epigenetic modification which can silence gene expression and stabilize repeats. A methyl group is added to cytosine when followed by guanine (CpG) and CpGs are enriched at the promoters of many genes and in retrotransposons. Nevertheless, only a small number of these CpG‐rich genes are actually regulated by methylation. These fall into three classes: imprinted genes, genes on the inactive X and germ cell‐specific genes. Methylation is reprogrammed (erased and re‐established) at two points during development: around implantation and the during germ cell development.
DNA methyltransferase 3a
(
DNMT3A
) and
DNMT3B
establish methylation patterns, with the help of the cofactor
DNMT3L
in the germ cells, then
DNMT1
maintains them during mitotic division. Failure of either process leads to developmental defects, sterility or embryonic death. Histone methylation and small RNAs (
ribonucleic acids
) have been implicated in directing the
methyltransferases
to particular genes or repeats.

Key concepts:

DNA methylation is associated with transcriptionally inactive chromatin and helps stabilize it.

Methylation in mammals occurs exclusively at cytosine followed by guanine (CpG).

CpG‐rich regions (CpG islands) are found at the start of many genes and in retrotransposons.

Methylation of CpG islands maintains repression on imprinted genes, genes on the inactive X chromosome, germ cell‐specific genes and certain retrotransposons.

Three key enzymes are involved, DNMT1, DNMT3A and DNMT3B, together with the cofactor DNMT3L.

DNMT1 maintains DNA methylation on all sequences during development.

DNMT3A and DNMT3L are essential for imprinting and retrotransposon repression in the germ cells.

There is a developmental cycle of changes in the level of genomic methylation, which is necessary for the correct reprogramming of imprinted and X‐chromosome genes for the next generation.

Evidence is growing that histone modifications determine which DNA sequences become methylated.
Phytophthora
Authors: Whisson Stephen C
Published: April 2010

Diseases of plants caused by species of the genus

Phytophthora

represent some of the most devastating diseases of crops worldwide. All known species of

Phytophthora

are plant pathogens. Although superficially similar to filamentous fungi, the

Phytophthora

species belong to the class oomycetes, and are more closely related to brown algae.

Phytophthora

‐incited disease may be controlled by genetically encoded resistance in the host plants. In cases where no host plant resistance to

Phytophthora

disease is available, application of control chemicals may be successful in controlling disease, although intensive chemical control is potentially environmentally damaging. Much recent research into

Phytophthora

biology has utilised modern molecular biology techniques. DNA (
deoxyribonucleic acid
) sequencing of three

Phytophthora

genomes has revealed an extraordinary repertoire of genes encoding proteins secreted by

Phytophthora

for the purpose of overcoming and subverting host plant innate and active defence responses, indicating pathogenicity in this genus to be a highly complex process.

Key Concepts

Species of
Phytophthora
cause some of the most destructive plant diseases known.

Phytophthora
species resemble fungi, but are phylogenetically distinct.

Some
Phytophthora
species have coevolved with their hosts, leading to a gene‐for‐gene system of matching plant resistance and
Phytophthora
avirulence gene products.

Some, but not all,
Phytophthora
diseases may be controlled by resistance in the host plant, or through the application of control chemicals.

Phytophthora
species secrete a complex array of proteins, including effectors, during invasion of plant tissues, some of which act to suppress plant defence responses.

Some effectors may be recognised by host plants, leading to resistance.

Other effectors may be required for pathogen growth and development during infection.

Numerous secreted
Phytophthora
proteins exhibit evidence of selection pressure from their plant hosts.
Counselling Issues around Preimplantation Genetic Diagnosis (
PGD
)
Authors: Ross Sarah
Published: April 2010

Preimplantation genetic diagnosis (PGD) is a highly specialized process which involves using assisted reproductive techniques for a couple to increase their chances of having a child that is unaffected by a serious known genetic disorder. It requires a multidisciplinary team of professionals comprising specialists in both assisted reproduction and genetics.

Before a decision by a couple to undergo PGD treatment, the counsellor needs to assess their situation, discuss their genetic risk and the process of PGD including the advantages and disadvantages while taking into account the emotional, practical and financial issues. This should enable the couple to make an informed decision about whether PGD is the most appropriate treatment for them. Counselling opportunities arise during and after a treatment cycle ensuring that couples are supported and fully aware of the implications of decisions that need to be made at each stage of the process.

Key concepts:

Preimplantation genetic diagnosis involves using assisted reproductive techniques to obtain embryos which are then tested for a known genetic condition, before transfer to the uterus.

Assisted reproductive techniques used in PGD involve artificially stimulating the ovaries to release large numbers of eggs which are collected and then fertilized using
in vitro
fertilization (IVF) or intracytoplasmic sperm insertion (ICSI).

Genetic counselling is a communication process that is associated with the occurrence or risk of a genetic disorder in the family.

FISH analysis – fluorescent
in situ
hybridization is a cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes. It uses fluorescent probes that bind to those parts of the chromosome that show a high degree of sequence similarity.

Preimplantation genetic haplotyping (PGH) involves taking a single cell and extracting DNA, which is then amplified before being used for DNA fingerprinting. PGH can be used where the exact mutation is not known or cannot be identified, as the technique scans for the presence of the genetic haplotype, which is associated with the familial disease gene region.
Small
RNA
s in Neurological Disorders
Authors: Lin Li , Vitale Angela V , Jin Peng
Published: April 2010

Small RNAs (
ribonucleic acids
) are a group of noncoding RNA molecules with modulation functions that span a broad range, from RNA modification to protein synthesis regulation. The expression of small RNAs is found to be widespread in all eukaryotes, and more than a third of protein‐coding genes in the human genome are regulated by small RNAs. Mounting evidence suggests that the appropriate spatiotemporal expression of small RNAs, in particular microRNAs (miRNAs), is required for both brain morphogenesis and nervous system development. Moreover, dysregulation of specific miRNAs is possibly correlated with the pathogenesis of neurodevelopmental disorders. Understanding the potential roles of small regulatory RNAs in neural development and various human neurological disorders could reveal therapeutic applications that involve restoring or inhibiting the function of small RNAs.

Key Concepts:

Small RNAs have been found in all major groups of eukaryotes.

Small RNAs are divided into four classes: microRNAs, small interacting RNAs, Piwi‐interacting RNAs and small nucleolar RNAs.

In humans, microRNAs play important functional roles, interacting with at least 30% of all mRNAs.

MicroRNAs are highly involved not only in normal brain function, but also in many developmental disorders.

Known to act on mRNAs, microRNAs will degrade, translationally inhibit or even upregulate mRNA expression.

One microRNA can affect the course of several neurodevelopmental disorders.

A full understanding of microRNA function will yield possible medicinal treatments.
Genetic Basis of Monogenic Forms of Parkinson Disease
Authors: Brockmann Kathrin , Gasser Thomas
Published: April 2010

There has been a plethora of genetic findings in Parkinson's disease (PD) during the last decade, and mutations in an increasing number of genes are found to cause monogenic forms of this disorder. To date, we know of 15 gene loci (PARK1–15) causing either autosomal dominantly or autosomal recessively inherited forms of PD. Proteins encoded by PD‐associated genes play important roles in different cellular functions and partially interact with each other suggesting that they share common pathways that lead to neuronal degeneration. At least some of these genes may also play a direct role in the aetiology of sporadic PD, and therefore it seems likely that the cellular pathways identified in familial variants of the disorder also elucidate the molecular pathogenesis in the sporadic form.

Recently, these genetic findings have begun to impact clinical practice. Here, we highlight these genetic advances, and discuss their importance for clinical practice.

Key Concepts:

Since both, monogenic and sporadic forms of PD, tend to share many overlapping features that include, most importantly, parkinsonism with nigrostriatal dopaminergic degeneration genetic findings imply common pathogenic mechanisms and may provide new insights in the specific molecular pathways underlying PD.

Since α‐synuclein was found to be the major component of Lewy bodies in familial and sporadic cases aggregation of this protein is thought to be a crucial step in dopaminergic neurodegeneration in both,
SNCA
‐linked as well as sporadic PD.

LRRK2
represents the most frequent form of autosomal dominantly inherited late‐onset PD offering the possibility to study the development of the disease in a sizeable population.

Presumption is rising that
parkin
,
PINK1
and
DJ‐1
which are associated with autosomal recessive forms of PD may act in a common pathway and that mutations within one of these genes imply ‘loss‐of‐function mechanism’ leading to cell death underlying mitochondrial and proteasomal dysfunction.

Longitudinal studies in presymptomatic mutation carriers may reveal pre‐motor changes by clinical, biochemical or imaging methods, indicating the very early phases of neurodegeneration. Therefore, further research in this population exploring neuroprotective or preventive measures are most promising to yield first results.
Deconstructing Gene Function throughENUMutagenesis
Authors: Acevedo‐Arozena Abraham , Ricketts Thomas , Corrochano Silvia
Published: April 2010

A great majority of genes present in the human genome are also present in the mouse, thus making it an attractive mammalian model organism to study gene function and dysfunction. Over the past few decades, the ability to manipulate the mouse genome has been developed in a variety of ways, including the ability to delete genes or introduce more subtle single mutations. A complementary methodology to create mutations in the mouse is to use chemical mutagenesis.N‐ethyl‐N‐nitrosourea (ENU) is the mutagen of choice for creating random point mutations throughout the genome in many model organisms. ENU mutagenesis is a powerful hypothesis‐generating approach currently being exploited to create new mouse models through both forward and reverse genetics approaches.

Key Concepts:

ENU produces mainly point mutations randomly throughout the genome.

ENU mutagenesis can be used in both forward and reverse genetics approaches.

ENU phenotype‐driven screens do not require previous knowledge of the gene to create new mouse models.

ENU phenotype‐driven screens identify new mouse models by means of phenotyping.
Genetics of Personality Disorders
Authors: Reichborn‐Kjennerud Ted
Published: April 2010

Evidence from family, adoption and twin studies indicate that genetic factors significantly influence liability to personality disorders and contribute to the co‐morbidity between personality disorders and between personality disorders and other psychiatric disorders. Molecular genetic studies aiming at identifying specific genes have been applied, to a limited extent, to personality. Significant associations have, however, been found with candidate genes related to neurotransmitter pathways, especially in the dopaminergic or serotonergic systems. Both quantitative and molecular genetic studies indicate that gene–environment correlation and interaction play a role in the aetiology of personality disorders. Methods like genome‐wide association studies, analyses of copy‐number variation, studies of rare genetic variants and epigenetic methods have not yet been applied to personality disorders, but will hopefully contribute to our future understanding of the causal mechanisms involved.

Key Concepts:

Personality disorders are significantly influenced by genetic factors.

Co‐morbidity between personality disorders and between personality disorders and other mental disorders are significantly influenced by shared genetic liability.

Candidate gene association studies indicate significant relationships between personality disorders and genes related to neurotransmitter pathways, especially in the dopaminergic or serotonergic systems.

Both quantitative and molecular genetic studies suggest that gene–environment interplay is involved in the aetiology of personality disorders.
Molecular Genetics of Anxiety
Authors: Sipilä Tessa , Hovatta Iiris
Published: April 2010

Anxiety is a normal response to a threatening situation. When anxiety is excessive and disturbs daily life and functioning, it can be diagnosed as an anxiety disorder. Anxiety disorders are typical complex disorders that are triggered by environmental factors in genetically susceptible individuals. Genetic variants in many genes have been shown to predispose to anxiety disorders, but the results have been difficult to replicate, most likely due to a small effect size of individual variants. Anxiety is an evolutionarily conserved response, and can therefore be fairly reliably modelled in rodents. Quantitative trait locus mapping and functional genomics and proteomics approaches in mouse models of anxiety have led to the identification of novel genes and pathways that are involved in the regulation of anxiety‐like behaviour. Some of these genes are expected to regulate anxiety in humans as well, and variants in them might predispose to anxiety disorders.

Key Concepts:

Anxiety disorders are complex diseases triggered by environmental factors in genetically susceptible individuals.

Genetic variants that predispose to anxiety disorders have been identified by candidate gene and genome‐wide association studies.

The effect size of the identified susceptibility variants for anxiety disorders seems to be small.

Features of human anxiety disorders can be fairly well modelled in animals, and different approaches have revealed novel genes and pathways that regulate anxiety‐like behaviour.

Combined information from several approaches, including human and mouse genetics, functional genomics, proteomics, epigenetics and neuroimaging are expected to reveal molecular mechanisms that regulate anxiety.
Molecular Genetics of Metastasis
Authors: Weber Georg F
Published: April 2010

Metastasis is the spread of cancer cells throughout the body. Although it is frequently the cause of death from malignant growths, it is the most poorly understood aspect of carcinogenesis. The underlying process of cancer cell dissemination is controlled by genetic programs in the tumour cells and in the host. The tumour cell‐intrinsic genetic programs of metastasis confer invasiveness and anchorage‐independence. The responsible genes are typically deregulated by aberrant expression or splicing. Organ preference of metastasis depends on more complex tumour–host interactions. Metastasis suppressor genes, when expressed, can negatively regulate tumour spread. The molecular genetics of metastasis has led to the development of diagnostic tests, based on gene expression profiles that help predict metastatic potential. Further, it has opened prospects for the targeting of key culprit genes in antimetastasis therapy.

Key Concepts:

Cancer invasiveness constitutes the breaking of tumour cells through tissue barriers and represents the earliest manifestation of metastasis.

The genetic basis of metastasis formation is the aberrant expression or splicing of stress response genes.

The biologic activity of metastasis‐mediating gene products is extensively regulated by posttranscriptional mechanisms.

Cancer metastasis is guided by two intrinsic characteristics of cancer cells, invasiveness and anchorage‐independent survival.

Cancer cell invasiveness is mediated by secreted proteases, homing receptors, cytokine ligands and associated signalling molecules.

The acquisition of invasiveness by tumour cells is accompanied by a characteristic, reversible remodelling, called the epithelial‐mesenchymal transition.

Cancers shed their tumour cells into the blood or lymph stream from the earliest stages of growth on; most cells die in the circulation.

Fully transformed cells can survive without anchorage for extended periods of time.

Genetic programs of metastasis encode consistent patterns of organ preference by individual malignancies.

Like other functions within cancer cells, the ability to metastasise is under positive and negative genetic control.
Molecular Genetics of Cardiac Arrhythmias
Authors: Wolf Cordula M , Berul Charles I
Published: April 2010

Knowledge derived from human genetics and from studies in animal models has led to the discovery of multiple molecular defects underlying inherited arrhythmias and cardiac conduction system diseases in structurally altered or normal hearts.

Minor disturbances at the molecular and cellular levels can initiate severe rhythm abnormalities. Some congenital heart diseases and cardiomyopathies carry a higher risk for conduction disturbances or arrhythmias. In the structurally normal heart, inherited cardiac arrhythmias or conduction system disease are most often primary electrical diseases. The underlying molecular defect in those disorders, also termed ion channelopathies, typically involves genes that encode ion channels, responsible for maintaining intracellular and extracellular electrolyte balance.

Advances in molecular biology and genetics facilitate the identification of factors that may predispose an individual with or without structural heart disease to arrhythmias or sudden death. Taking those discoveries into clinical practice improves risk stratification and allows potential identification of new therapeutic targets.

Key Concepts:

Sudden unexpected cardiac death in the pediatric population is a devastating event with an incidence of approximately 1–6 in 100 000 per year and in some cases is the first presentation of a previously undiagnosed disorder.

Inherited arrhythmias and cardiac conduction system disease frequently occur in pediatric patients with congenital heart disease but can also be associated with a structurally normal heart.

Mutations in genes encoding for cytoskeletal proteins, sarcomeric proteins and ion channels are responsible for the majority of inherited arrhythmias associated with the structurally normal or abnormal heart.

Identifying the molecular basis of congenital arrhythmias optimises patient screening, risk stratification and allows genotype‐directed therapies of patients at risk for sudden cardiac death.
Aeration, Mixing, and Hydrodynamics, Animal Cell Bioreactors
Authors: Godoy‐Silva Ruben , Berdugo Claudia , Chalmers Jeffrey J.
Published: April 2010

Mixing and aeration are normally used to provide a homogeneous, suitable environment for cells in a bioreactor. In spite of the large cumulative experience in the use of bioreactors in the biotechnology industry, there are still challenges when scaling‐up animal cell cultures. Remarkable advances have been achieved over the last two decades in designing and applying mixing and aeration strategies, as well as understanding the effects of hydrodynamic forces on cell cultures.

This section reviews the basic concepts and current practices for mixing and aeration in bioreactors, with focus on stirred tank bioreactors (STR), as most of the processes for recombinant proteins, antibodies, and vaccines involve the use of STR. Current methods of oxygen supply in STR include surface aeration and gas sparging, although the use of perfluorocarbons, oxygen carriers and membranes has been investigated. Sparger design and the role of CO2accumulation and removal are discussed. Also, a summary of the main aspects involved in mixing is presented, including tank characteristics, impeller geometry, and power drawn. Finally, this review explores several different approaches that have been taken in order to unveil the response of animal cells to the hydrodynamic forces generated inside bioprocessing devices.
Agricultural Biotechnology, Food Safety, Risk, Consent, and Ethics
Authors: Thompson Paul B. , Hannah William
Published: April 2010

The ethical rationale for acceptable food safety risks can be interpreted according to two competing paradigms. The expected value paradigm stipulates that risks are functions of the harm associated with an adverse outcome accruing as a result of food consumption and the probability of that outcome. Although quantification of expected values for food safety presents challenges, the standard for acceptable risk is conceptualized as optimization of expected values. In present practice, optima for food safety risks are generally characterized as de minimus criteria. The alternative paradigm presumes that longstanding patterns of social food regimes constitute background practices not subject to moral judgment or risk assessment. Deviations from such patterns are understood as risky, and become acceptable only under the condition of informed consent for risk‐bearers. While in many cases, both paradigms converge on a common policy, for foods derived from genetic engineering, they have diverged.
Animal Cell Culture Media
Authors: Vijayasankaran Natarajan , Li Jincai , Shawley Robert , Chen Aaron , Shiratori Masaru , Gawlitzek Martin , Li Feng , Kiss Robert , Amanullah Ashraf
Published: April 2010

Fed‐batch cell culture processes are the standard platform technology for the synthesis of high value biopharmaceutical proteins. Recent advances in cell line development and in the optimization of culture medium have enabled the operation of fed‐batch processes at significantly higher volumetric productivities than previously realized. While a robust basal medium is essential to ensure high productivity, a well‐developed feed medium coupled with an appropriate feeding strategy are essential for sustaining it over the course of the culture duration. Furthermore, optimization of cell culture medium needs to be cognizant of specific goals for its use. Different optimization strategies are adapted for developing platform media applicable for multiple cell lines and customized media developed for specific cell lines. While volumetric productivity continues to be an important parameter for cell culture medium optimization, the developed medium should also be robust during implementation in biopharmaceutical manufacturing facilities. The developed medium should be easy to prepare and have a long shelf life to ensure ease of process implementation in multiple commercial and clinical‐scale manufacturing sites. Due care should be taken to ensure that optimization of media does not lead to unacceptable alterations in the quality of the expressed protein. This article will address all these aspects that ensure the efficient optimization and implementation of animal cell culture media.
Animal Cells, Hybridomas, Human Antibody Production
Authors: Warren James C. , Subramanian Shyamsundar
Published: April 2010

Cellular response to perturbations in the microenvironment manifests as a surge of physiological changes that have great impact on cellular metabolism and propagation. In bioprocess systems, mammalian cells engineered for the production of monoclonal antibodies or therapeutic proteins are sensitive to fluctuations in the culture environment. These fluctuations often directly translate to changes in maximum attainable cell concentration and/or specific protein productivity. In conjunction with feeding strategy optimization, the ability to understand and optimize the physical environment of animal culture systems is key to achieving a process that delivers consistent production of high titer batches. In this article we have reviewed comprehensively two critical physical culture parameters: osmolality and temperature, for their effects on general cellular physiology as well as their impacts on overall culture performance in bioprocess systems. Extreme levels of osmolality lead to volume‐regulatory responses, cytoskeletal reorganization, and trigger distinct cellular signaling pathways. Cellular responses to hypothermic conditions include reduced metabolic and growth rates, reduction of apoptosis frequency, and a cold‐shock response which involves the increased synthesis of several proteins. Exposure of cells to hyperosmotic conditions and/or subphysiological temperature (32–35°C) has been shown to enhance specific protein productivity in bioprocess systems. As live viruses are also commonly produced in industrial cell culture systems for vaccine processes, we have extended the scope of this article to include the effects of fluctuations in culture osmolality and temperature on the production of live viruses.
Animal Cell Types, Hybridoma Cells
Authors: Heilmann K. , Micheel B.
Published: April 2010

The hybridoma technology developed from Köhler and Milstein over 20 years ago is till today the scientific standard in generating monoclonal antibodies and demonstrates a hallmark in biotechnology and biomedicine. This basic method and all arising technologies opened up a new field of experimental designs and innovative results to understand and clarify courses in diseases. The possible application of antibodies in research leads to well‐defined characterizations of cell types, cell‐cell and cell‐matrix interactions and correlation of signaling cascades. These perspectives indicate a continuous requirement and therefore a huge global demand for antibody molecules, related detection markers, and biomedical tools. In the course of this development, a multitude of new techniques is necessary and will be designed in future to simplify the generation of human therapeutic antibodies which seem to be a highly effective tool in the treatment of malignant or autoimmune diseases.
Antibiotics: Biosynthesis, Generation of Novel Compounds
Authors: Weber Tilmann
Published: April 2010

Many antibiotics and other bioactive molecules originate from biological sources, mainly bacteria and fungi. In this article, the biosynthetic principles of the three most important classes of antibiotics are discussed and examples of the biotechnological potential of pathway engineering are presented.

Polyketides, among them medically important antibacterial drugs like tetracycline or erythromycin, are assembled from basic acyl‐CoA building blocks by a mechanism that is closely related to fatty acid synthesis. Another important group of antibiotics are modified peptides like penicillin or vancomycin which are synthesized by complex modular megaenzymes. These nonribosomal peptide synthetases use proteinogenic as well as nonproteinogenic amino acids as substrates. In addition some other peptide antibiotics, like the lantibiotic nisin which is widely used as a food additive, are synthesized by the cellular ribosomal protein biosynthesis machinery and subsequently modified by specific enzymes. Aminoglycoside antibiotics like streptomycin are assembled from complex sugar or sugar‐like molecules which are specifically synthesized during secondary metabolite production.

The elucidation of the molecular machinery of antibiotic biosynthesis enabled technologies that can be used to optimize the secondary metabolites by genetic engineering. In this article, some strategies are highlighted which allow the modification of secondary metabolites in ways that were hard to achieve using only synthetic chemistry approaches.
Protein Aggregation and Precipitation, Measurement and Control
Authors: Schein Catherine H.
Published: April 2010

Aggregation is both a blessing and a curse to the biochemist seeking to purify and use recombinant proteins. Reversible aggregation/precipitation induced by agents such as polyethylene glycol and salts can be used to purify proteins. However, proteins often undergo uncontrolled and irreversible aggregation that prevents regeneration of activity. This article summarizes methods to measure aggregation and to determine the intrinsic solubility of proteins. Much of this research has been driven by the need to formulate medically useful proteins so that they remain soluble, and to develop treatments for diseases that involve protein aggregation, such as Alzheimer's and other neurodegenerative diseases.

Theoretical treatments of the effects of co‐solvents on the solubility of proteins, including using empirical data to deriveatomic solvation parameters(ASP), may be useful for some applications. Mathematical models and protein phase diagrams have been developed for common precipitants, although there is no common basis for theira prioriuse with a given protein. There are also some general rules for designing mutants with reduced aggregation tendencies. To this end, computational methods may be used to estimate the solvent exposure of residues in 3D‐structures, predict surface patches that may dictate protein–protein interactions, and to model the 3D structure.