bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetically Modified Plants
Authors: Halford Nigel G 
Published: April 2014

AbstractThe genetic modification of plants is now an established tool for plant breeders in many parts of the world, with the area of land used for genetically modified (GM) crop cultivation rising to 170 million hectares by 2012. This article puts genetic modification of plants into the context of scientific plant breeding, and describes the techniques that are used to transform plants and that define the term genetically modified. The design of transgenes is described, as is the use of selectable and visible marker genes. The use of GM crops in commercial agriculture is covered in detail, including GM crops that may be developed for commercial use in the near future. The barriers to the continued development of crop biotechnology are considered, notably the cost, the associated issue of regulatory compliance and the problem of consumer acceptance. The consequences of science losing the GM crop debate are discussed.Key Concepts:Genetic modification (GM) is a term used to describe the artificial introduction of a gene or genes into an organism's genome.Genetic modification is now an established tool in plant breeding in many parts of the world.Genetically modified crops were grown on 170 million hectares of land in 2012.‘Input’ traits such as herbicide tolerance and insect resistance are by far the most successful GM traits.Other GM traits in commercial crops include virus resistance, modified oil content, increased nutritional value, drought tolerance and the synthesis of high‐value, nonfood products (biopharming).Increased vitamin A content, improved food safety and bioremediation are targets for GM crop programmes that may be commercialised in the next few years.GM is the most heavily regulated area of plant breeding, and over‐regulation is a significant barrier to the development of the technology.Consumer acceptance of GM crops remains a difficult issue in some regions, notably Europe.
Leucine Zippers
Authors: Hakoshima Toshio 
Published: April 2014

Abstract

The leucine zipper (ZIP) motif consists of a periodic repetition of a leucine residue at every seventh position (heptad repeat) and forms an α‐helical conformation, which facilitates dimerisation and in some cases higher oligomerisation of proteins by forming a parallel helix–helix association stabilised by formation of an interhelical hydrophobic core involving leucine side chains. These nonpolar interactions are important for stabilisation of the ZIP structures, whereas specificity of these dimerisation and oligomerisation is mediated by electrostatic interactions, such as formation of salt bridges. In many eukaryotic gene regulatory proteins, the ZIP motif is flanked at its
N
‐terminus by a basic region containing characteristic residues that facilitate
deoxyribonucleic acid (DNA)
binding and is referred to as bZIP. ZIP‐related heptad repeats are frequently found in a variety of proteins and catalyse dimerisation/oligomerisation by forming both parallel and antiparallel coiled coils.

Key Concepts:

A heptad repeat of leucine residues, leucine zipper (ZIP), is an important sequence motif facilitating protein–protein interactions.

ZIP forms an amphiphilic α helical structure, in which two residues that are separated by seven residues in sequence are located at nearly the same molecular surface in an α helix.

The amphiphilic nature of the ZIP helix facilitates protein dimerisation by forming a parallel helix–helix association.

Leucine side chains extending from one α helix interdigitate with those displayed from an α helix of a second polypeptide like a zipper to stabilise formation of an interhelical hydrophobic core.

The specificity of the ZIP dimerisation is mediated by electrostatic interactions, such as formation of salt bridges.

ZIP is frequently fused with other sequence motifs to produce biologically important functional structural modules.

The ‘basic region ZIP’ (bZIP motif) is a fusion between a segment that is rich in basic residues facilitating DNA binding and ZIP, forming a class of eukaryotic transcription factors.

The DNA binding specificity of bZIP is determined by the basic region that directly binds a class of palindromic DNA sequences.

ZIP‐related sequence motifs containing an incomplete heptad repeat are frequently found in a variety of proteins and catalyse dimerisation/oligomerisation by forming both parallel and antiparallel coiled coils.
Chromosome Preparation
Authors: Blennow Elisabeth , Iwarsson Erik 
Published: April 2014

AbstractStandard chromosome preparations can be obtained from various tissues containing dividing cells. The easiest way to obtain metaphases for constitutional karyotyping is to take a blood sample and culture the lymphocytes. Amniotic fluid obtained by amniocentesis, or preparation of chromosomes from chorionic villi, may be used for prenatal diagnosis. Bone marrow is the tissue of choice for studies of acquired chromosome abnormalities in haematological malignancies. Chromosome preparations can also be made from cultures of solid tissues, like tumours, fetal skin, muscle, placenta, lung, kidney and liver. To have an unlimited source of cells, immortalised cell lines may be established, like tumour‐derived cell lines or cell transduction of normal cells with genes from adeoxyribonucleic acid (DNA)tumour virus. To achieve a higher resolution using fluorescentin situhybridisation, methods for preparation of released, less‐condensed and linearised DNA fibres have been developed.Key Concepts:Metaphase spreads may be obtained from various tissues on condition that the cells are spontaneously dividing or may be cultured and in some cases chemically stimulated to divide by the addition of a mitogen.The easiest way to obtain metaphase chromosomes for constitutional karyotyping is to take a blood sample and culture the lymphocytes.Amniotic fluid or chorionic villi cells may be used for preparation of chromosomes for prenatal diagnosis.Chromosome preparations from bone marrow may be used for studies of acquired chromosome abnormalities in haematological malignancies.The cultures may be synchronised in order to achieve a better quality of chromosome preparation.Chromosome preparations can be made from cultures of solid tissues after disaggregation.To have an unlimited source of cells, immortalised cell lines may be established.To achieve a higher resolution using fluorescentin situhybridisation (FISH), methods for preparation of released, less‐condensed and linearised DNA fibres may be used.
Sex Chromosomes
Authors: Lucchesi John C 
Published: April 2014

Abstract

Sexual reproduction increases the number of different genetic constitutions that are present at each generation and that can be acted on by natural selection. In many organisms, the genetic information required for the differentiation of fertilised eggs into individuals of different sexes is contained on a special pair of chromosomes: the sex chromosomes. All sex chromosomes were derived from pairs of ordinary chromosomes (autosomes). In some instances, the autosomes acquired a gene represented by two alleles, one of which was male determining. In other instances, the presence of one of the two alleles of the sex‐determining gene on both chromosomes led to the differentiation of one sex, whereas its presence on only one of the two autosomes led to the differentiation of the other sex. In this case, the allele on the other chromosome was neutral with respect to any effect on sex determination. The autosome with the male‐determining allele or with the neutral allele accumulated mutations that inactivated most of the other genes present throughout their length. This led to a difference in the dosage of these genes between the sexes and to the evolution of mechanisms that compensate for this dosage difference.

Key Concepts:

In many organisms, sex is determined by the presence of specific chromosomes – the sex chromosomes.

These chromosomes have evolved from particular pairs of autosomes.

In all cases, the determination of sex is achieved by the expression of one or a few genes that are present on the sex chromosomes.

The expression of these genes causes the differentiation of one of the two sexes; the other sex develops by default.

The presence of different sex chromosomes in the two sexes can cause differences in the dosage of genes that are present on these chromosomes but that have critical functions in both sexes.

When such a difference in these genes would be harmful to one of the two sexes, regulatory mechanisms that compensate for the difference in the dosage of these genes have evolved.
Gene Targeting by Homologous Recombination
Authors: Reh Wade A , Vasquez Karen M 
Published: April 2014

Abstract

Gene targeting by homologous recombination involves the exchange of genetic information between genomic and exogenous
deoxyribonucleic acid (DNA)
molecules via crossover events. These exchanges are guided by homologous sequences acted on by enzymatic machinery of the cell. Homologous recombination provides a mechanism for targeting defined modifications into genes of interest, making gene‐targeting technologies valuable tools to explore gene function and to develop human, genetic disease models. Gene targeting, however, is inefficient, making the process challenging. Advances in technology now allow us to direct repair enzymes to the targeted site by inducing site‐specific DNA damage using zinc‐finger nucleases, transcription activator‐like effector nucleases, clustered regularly interspaced short palindromic repeats and triplex‐forming oligonucleotides. Further, antirecombinogenic pathways can now be transiently suppressed using
ribonucleic acid (RNA)
interference (RNAi) and other small molecule approaches. These and other techniques can greatly enhance gene‐targeting efficiency. The coincident development of human stem cell technology brings forth the potential of gene‐targeting strategies for therapeutic application.

Key Concepts:

Homology‐directed gene targeting utilises homologous recombination to introduce defined modifications into sequences of interest in mammalian genomes.

Gene‐targeted knockout and knock‐in models are instrumental in elucidating gene function and studying human genetic diseases.

Combining stem cell and gene‐targeting technologies opens potential avenues for gene therapy.

Recent technological advances have greatly enhanced gene‐targeting efficiencies.

Due to technological advances, most genes in a variety of mammalian species can now be manipulated by homology‐directed gene targeting.
Strigolactones: A New Class of Plant Hormones with Multifaceted Roles
Authors: Prandi Cristina , Cardinale Francesca 
Published: April 2014

Abstract

Strigolactones (SLs) are terpenoid lactones produced mainly in plant roots and initially identified as seed germination stimulants for parasitic weeds. In 2005, they were described also as boosters of hyphal branching in arbuscular mycorrhizal fungi, and thereby as promoters of arbuscular mycorrhizal symbiosis. In 2008, they emerged as a new class of plant hormones controlling plant architecture through repression of shoot branching. Since then, several new roles were discovered for SLs: in the adaptive responses to a number of environmental stimuli (including light, osmotic stress, interaction with pathogens and nodulating bacteria), and in several aspects of plant development (including seed germination for nonparasitic plants, hypocotyl elongation, reproduction, leaf senescence and nodulation). The biosynthetic and perception/transduction systems of SLs are being elucidated, and the first mechanistic models presented.

Key Concepts:

Strigolactones are the key nutrient allocators regulating plant development at the interface between plants, beneficial and detrimental (micro)organisms, and abiotic factors.

Strigolactones induce hyphal branching in AM fungi and facilitate the establishment of symbiosis.

Strigolactones inhibit shoot branching.

Strigolactones affect root architecture and root development depending on nutrients availability.

Synthetic SLs (analogues and mimics) are used in pharmacological applications to plants and fungi to decipher the structure–activity relationship.

Structure–activity relationship (SAR): Different structures are tested for bioactivity in order to pinpoint which part of the molecule is essential for bioactivity and which can be considered only ‘decoration’.
Two‐Component Signalling in Plants
Authors: Burr Christian A , Sacks Carly M , Kieber Joseph J 
Published: April 2014

Abstract

Two‐component signalling pathways are used by bacteria to perceive and respond to a wide variety of environmental signals. In their simplest form, these are comprised of a histidine kinase receptor, whose activity is regulated by a signal, and a response regulator, whose activity is controlled by Asp phosphorylation mediated by the histidine kinase. Plants use two‐component elements to respond to endogenous and environmental signals. The plant pathways are either an extended version of the two‐component pathway called a phosphorelay or include degenerated elements that no longer function as histidine kinases. These elements are conserved throughout the plant kingdom, although they are best understood in the model

Arabidopsis thaliana

. The most complete and best understood of these is the signalling pathway for the phytohormone cytokinin, which is perceived by endoplasmic reticulum‐localised histidine kinase receptors and ultimately regulates the phosphorylation of a set of response regulators that mediate the transcriptional response to cytokinin.

Key Concepts:

The canonical two‐component system consists of a histidine kinase and response regulator protein.

Multiple permutations of the canonical two‐component system exist, including a multistep phosphorelay system.

Plants respond to a variety of signals using two‐component signalling systems, including cytokinin, ethylene and light.

Two‐component signalling elements are conserved in both dicot and monocot plant species.

Cytokinin, a plant hormone, uses a multistep phosphorelay system to transduce its signal from membrane‐bound receptors to the nucleus to mediate transcription of cytokinin response genes.
Water Use Efficiency of Cultivated Crops
Authors: Katerji Nader , Mastrorilli Marcello 
Published: April 2014

AbstractThe concept of crop water use efficiency (WUE), determined by the ratio between the marketable yield and the seasonal values of actual evapotranspiration, has become a suitable tool for analysing the strategies that allow attaining the best use of water in agriculture. Crop WUE is easy to quantify from field measurements, but it is a complex indicator because wide differences can be observed for the WUE values of the same species cultivated under the same site.In this article, the major causes of the large range of WUE values are identified and analysed. The authors demonstrate that the WUE variability can be ascribed mainly to three factors: agro‐techniques (water regime, mineral supply and water quality), crop (species, varieties and sensitivity of the growth stage to the stress) and environment (climate, atmospheric pollution, soil texture and climate change).Understanding and taking into consideration the WUE variability are primary conditions for advanced studies on WUE. The paths for further research and management programmes, allowing to valorise the water in agriculture, can be drawn from the analysis reported here.Key Concepts:To ameliorate the efficiency of water used by cultivated crops is one of the three possible strategies for increasing water sustainability in agriculture.To attain this objective, ecophysiological and agronomical approaches can be used.The ecophysiological approach refers to values of carbon assimilation and transpiration rates per leaf unit area. It helps in understanding global results obtained from the agronomical approach.In the agronomic approach, the concept of crop use water efficiency (WUE) refers to final yield and to total water consumed by crops, under field conditions. They are key data to manage the crop production.Crop WUE is easy to quantify from field measurements, but it is a complex indicator because of its intrinsic variability.The major causes of WUE variability are identified and analysed in this review: crop, environment and agro‐techniques.If the causes of such variability are known and taken in the right consideration, the concept of WUE can represent an interesting tool for studying how to valorise the water in agriculture.
Lifestyle Responses to Genetic Susceptibility to Type 2 Diabetes
Authors: Thirlaway Katie , Davies Lindsey 
Published: April 2014

Abstract

Type 2 diabetes is a serious condition that often leads to complications and increases the risk of a number of other diseases. The prevalence of type 2 diabetes is rising and is associated with western lifestyles; overconsumption of high calorie foods and predominantly sedentary daily routines. However, recent advances in genomic research has established that some individuals are more ‘at risk’ from behavioural risk factors than others. Type 2 diabetes therefore reflects multifactorial inheritance in which susceptibility is determined by the complex interaction of multiple genes with environmental and lifestyle factors. There has been considerable debate in the literature about whether genetic information could undermine healthy lifestyle decisions particularly for conditions like type 2 diabetes with multifactorial aetiology. The evidence that personalised genetic risk information engenders feelings of fatalism is mixed. Optimising lifestyle responses to genetic susceptibility to diabetes requires not only an appreciation of the complexity of disease aetiology by health professionals, but also an understanding of how individuals interpret and respond to this genetic risk.

Key Concepts:

Type 2 diabetes is a complex multifactorial disease.

Although type 2 diabetes is considered a ‘lifestyle’ disease it has a strong genetic component.

Information about genetic aetiology has the potential to influence lifestyle choices.

Understanding that type 2 diabetes has a genetic aetiology may increase fatalism in individuals.

Communication of genetic risk is important to ensure that healthy lifestyles are supported.
Transgenerational Impact of Nutrition on Disease Risk
Authors: Roseboom Tessa , Painter Rebecca 
Published: April 2014

Abstract

Although the evidence for transgenerational epigenetic inheritance from animal experiments is strong, there is very little evidence from human studies. The few studies in human populations that have been able to investigate several generations seem to suggest that transgenerational epigenetic inheritance occurs in humans as well and that this may occur both through the maternal and through the paternal line. We are only beginning to appreciate the generation‐spanning effects of poor environmental conditions during early life, which may be particularly relevant to populations in transition between traditional and Western lifestyles. This may shed light on the epidemic of diabetes, obesity and cardiovascular disease. Public health strategies that focus on improved nutrition during critical periods of growth and development may provide a means of promoting cardiovascular and metabolic health and ultimately benefit generations to come. However, the full impact of the strategies may not be apparent for decades.

Key Concepts:

A popular definition of epigenetics states that it concerns the study of mitotically and/or meiotically heritable changes in gene expression that occur without a change in DNA sequence.

Under this definition, epigenetic regulation has a role at two levels. First, it is involved in development, leading to the differentiation of cells in different tissues and organs and assuring the faithful inheritance of their differentiated state over mitotic cell divisions. Second, epigenetic states can be inherited meiotically, from one generation to the next.

Transgenerational effects refer to effects being transmitted from one generation to another. Although some biologists consider all effects that concern both parents and offspring to be transgenerational, the author would like to distinguish transgenerational effects from parental and grandparental effects.

In addition to contributing their DNA, parents can influence their offspring in many ways, for example, by contributing bioactive molecules in the egg and sperm cytoplasm, by providing nutrients and hormonal information during embryogenesis and by provisioning and taking care of offspring after birth.

Many of these parental and grandparental effects will not have an epigenetic basis. In a pregnant woman, for instance, not only are the mother and foetus exposed to the environmental stimuli but also are exposed the foetus' primordial germ cells, which will eventually produce the grandoffspring.

Transgenerational epigenetics is defined here as the study of the transfer of nongenetic information between organisms, setting it apart from the transfer of epigenetic information between cells of the same organism.
Entrepreneurship in Architectural Robotics: The Simultaneity of Craft, Economics and Design
Authors: Feringa Jelle 
Published: April 2014

AbstractWhat do Odico Formwork Robotics, RoboFold, Machineous, ROB Technologies and GREYSHED share in common? They are all architectural robotics startups. Jelle Feringa, Chief Technology Officer at Odico, places the phenomenon of the architectural robotics entrepreneur in a historical and cultural context while highlighting the very practical role startups are poised to play in bridging the gap between academic research and industry, by providing the building industry with much needed new software tools.
Crisis! What Crisis? Retooling for Mass Markets in the 21st Century
Authors: Verebes Tom 
Published: April 2014

AbstractFrom his base in Southeast Asia, Tom Verebes, Associate Professor in the Department of Architecture at the University of Hong Kong (HKU), asks what the hardcore realities are for robotics in architecture in this new ‘Asian Century’. At a time when China strives to accommodate 10 million new urban citizens each year by rolling out high‐rise residential blocks with standardised serial production techniques, what hope is there that the homogeneous Chinese city will apply robotic tools of mass customisation for the construction of distinctive, rather than generic structures?
Viscosity Ratio and Interfacial Tension as Carbon Nanotubes Distributing Factors in Melt‐Mixed Blends of Polyamide 12 and High‐Density Polyethylene
Authors: Zonder L. , Mccarthy S. , Rios F. , Ophir A. , Kenig S. 
Published: April 2014

ABSTRACTPolyamide 12 (PA12)/high‐density polyethylene (PE)/carbon nanotubes (CNTs) composites were prepared by three melt mixing sequences; premixing the CNT in the PA phase, premixing the CNT in the PE phase, and simultaneous mixing of all components. The interfacial tension and viscosity ratio between the components were altered by modifying the PE minor phase with PE‐graft‐maleic anhydride (PE‐g‐MAH) and by using different melt flow rate PE minor phase. Scanning electron microscopy (SEM) and volume resistivity (VR) measurements show that when the matrix's viscosity is greater than that of the dispersed phase, simultaneous mixing and premixing the CNT in the PE phase form a unique microstructure that yields a VR that is 4–6 decades lower than when premixing the CNT in the PA phase. When the viscosity of the dispersed PE phase is greater, kinetic restrictions limit the migration of the CNTs from the PE phase, resulting in high VR values for all mixing procedures. The wetting parameter was used to calculate the thermodynamic drive of the CNTs localization. It was found that the MAH modification reduces the interfacial tension between the CNT and the modified PE phase, which results in selective localization of CNT in there rather than in the PA phase. This observation was confirmed in SEM imaging and also expressed in high VR values of these composites.