bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of hydrocolloids In low fat spreads
Authors: Hermansson Anne-Marie M , Jordansson Elvy
Published: November 2023

The process for producing spreads is mainly designed to control fat crystallization and fat crystal interactions. The lower the fat content the more we need to know about the possibilities of controlling the aqueous phase both with regard to composition and processing conditions. This paper will discuss features of the aqueous phase at several structural levels. The distribution between the fat and the aqueous phase is of major importance. Most low-fat spreads are fat-continuous, but there are also bi continuous and water-continuous products on the market. Variations in composition and processing conditions can lead to large variations in the particle size and the shape of aqueous domains. There are also variations within the aqueous phase, both with regard to density fluctuations and the distribution of hydrocolloids.
Low calorie food formulation the use of carbohydrates as fat replacers
Authors: Lawson P
Published: November 2023

The increasing trend in nutritional and health awareness is leading to a demand from the consumer for new reduced or low calorie foods. Excess fat intake specifically of saturated fats, has been identified by health professionals as a major factor in the ailments of civilised societies. The American Heart Association recommends a reduction in fat consumption so that not more than 30% of total calorie intake is derived from fat. This proposal has been endorsed by the health authorities in many other countries. It is clear, therefore, that we have to reduce fat consumption and to increase our intake of preferably complex carbohydrates.
The surface shear rheology and surface tension of carboxymethylcellulose solutions in the presence of NaCl, sodium lauryl sulphate and phosphate buffer pH 1.9
Authors: challacombe S
Published: November 2023

surface films on ageing. The aim of the present study was to investigate the effect of lM NaCl, phosphate buffer, and sodium lauryl sulphate on the surface properties of 1% and 2% carboxymethyl cellulose solutions. The surface shear modulus was determined using an oscillating ring surface shear rheometer and the surface tension using a Kruss tensiometer Kl2. Results suggest that carboxymethyl cellulose solutions formed elastic films the strength of which were decreased by addition of NaCl, sodium lauryl sulphate or use of a phosphate buffer, pH 1. 9. The failure of NaCl to increase the surface shear modulus of solutions, as has previously been demonstrated for gum acacia, may be due to alterations in the 6 point of the carboxymethyl cellulose solutions.
Dyed, crosslinked substrates for the assay of polysaccharide endo-hydrolases
Authors: Mccleary Barry V , Francis Ann , Casey Ailin
Published: November 2023

Highly sensitive and specific substrates for the assay of polysaccharide endo-hydrolases have been developed. These substrates are dyed and crosslinked, high purity polysaccharides and have been incorporated into tablet form for ease of use. Substrates for the measurement of endo-!3-xylanase, a-amylase, limit-dextrinase, endo-arabinanase, cellulase and 13-mannanase are now available and others are under development. The assay format simply involves adding the tablet to an aliquot of the solution to be assayed, incubation for 10 min, termination of the reaction, filtration and measurement of the absorbance of the filtrate.
The molecular structure of tamarind seed polysaccharide
Authors: P.Millane R , V.Narasaiah T
Published: November 2023

The ordered molecular structure of tamarind seed polysaccharide has been studied using x-ray fiber diffraction analysis and molecular modelling. The results show that, in the solid state, the backbone adopts a cellulose-like conformation, and that three types of conformation are sterically accessible to the sidechains. Each sidechain conformation is consistent with sidechain-mainchain interactions that would increase chain stiffness over that of similar, but less substituted, polysaccharides, as is observed.
A new phase transition corresponding to the formation of the amylose-lipid complex in wheat starch
Authors: Oliver G
Published: November 2023

The presence of an amylase-lipid complex is an important factor in determining the quality of cereal-starch based flours. However, it is not known whether this complex is naturally present in starch or whether it is formed from the components during gelatinisation, as happens when additional lipids are added to starch. The present differential scanning calorimeter (DSC) study examined wheat starch/water mixtures a t 1o°C/min and 2.5°C/min. The slower heat in rate revealed an exothermic phase transition, occurring during gelatinisat1on, that may be associated with the formation an amylase-lipid complex.
Chromosome instability syndromes
Authors: Howell R T , Taylor A M R
Published: November 2023

A number of clinically diverse inherited human diseases, unified by the abnormal behaviour of their chromosomes, are sometimes grouped together under the heading of chromosome instability syndromes. Depending on the syndrome, the abnormal chromosome behaviour may take the form of:
Introduction
Authors: Yamamoto Keith R
Published: November 2023

Molecular biology, beneath its trendiness and jargon, is basically a set of tools. That is, it is not an intellectual niche in the body of biological knowledge, but instead a collection of methodologies that defines and supports reductionist strategies —approaches that seek simplified experimental systems and minimized experimental variables. Be that as it may, this set of tools has absolutely revolutionized biological research. And perhaps nowhere is the influence of this technology more evident than in studies of eukaryotic transcription and the regulation of its initiation.
Transcription of exogenous genes in mammalian cells
Authors: docherty Kevin , Clark Andrew R
Published: November 2023

The expression of exogenous genes in mammalian cells in culture has proved invaluable in a wide variety of applications. The advantages over the use of E. coli for the large-scale production of biologically active polypeptides stem from the ability of mammalian cells to undertake post-translational modification (e.g. proteolytic processing or glycosylation) of the gene product.
Identification and characterization of eukaryotic transcription factors
Authors: Jackson Stephen p.
Published: November 2023

An important and widely used mechanism for regulating gene expression in eukaryotic organisms is that of modulating the efficiency of transcriptional initiation. Molecular genetic analysis of transcriptional promoters recognized by RNA polymerase II has revealed that accurate and efficient transcription requires a variety of cisacting sequence elements. These elements are recognized and bound by sequencespecific DNAbinding transcription factor proteins that then serve to either activate, or in some cases repress, transcriptional initiation by the general transcriptional apparatus (1-4). A great many sequencespecific transcription factors exist; they differ from one another in the DNA sequence(s) that they recognize and in the way that they are regulated themselves. For example, some transcription factor are restricted to particular cell types, others are expressed only at certain stages of development, while yet others are activated only in response to a particular physilogoical agent such as a hormone. By employing different combinations of these sequencespecific factors, highly complex and unique patterns of gene expression are achieved. This chapter describes various approaches that are used to define, purify, and characterize sequencespecific transcription factor proteins.
Analysis of protein-DNA interactions
Authors: Garabedian Michael j. , labaer joshua , liu, wei-hong , Thomas jay r.
Published: November 2023

An important finding of contemporary studies in molecular biology is that much of the process of cellular differentiation is regulated at the level of gene transcription. Analyses of cloned genes have revealed that in a given tissue or cell type, gene expression is determined largely by proteins that bind to specific DNA sequences linked to those genes. This chapter considers in detail numerous procedures for characterizing these important protein-DNA interactions.
Leishmania and Trypanosoma
Authors: Williams J E
Published: November 2023

The genera Leishmania and Trypanosoma belong to the family Trypanoso-matidae of the order Kinetoplastida. All members of this family are parasitic and possess a single locomotory flagellum, which arises from a flagellar pocket. All members of the Kinetoplastida have a DNA-containing organelle, the kinetoplast, which is part of a simple mitochondrion and is located adjacent to the flagellar basal body. Only the Leishmania and Trypanosoma have species which infect and cause disease in man. Two genera of sandfly act as vectors, Phlebotomus in the Old World and Lutzomya in the New World.
Study of protein phosphorylation in intact cells
Authors: Garrison James C
Published: November 2023

Investigators studying mechanisms of cell regulation often need to establish that certain proteins are phosphorylated in intact cells. The usual technique employed for these studies is to label the cellular ATP pools with 32P prior to applying a stimulus that is expected to change the phosphorylation state of certain proteins or sets of proteins. The phosphorylated proteins are extracted from the cell, resolved on SDS-polyacrylamide gels, and visualized using autoradiography.
Identification of novel protein (serine/threonine) phosphatase genes in Saccharomyces cerevisiae, Drosophila melanogaster, and man by the polymerase chain reaction
Authors: Chen Mao Xiang , Cohen Patricia T W
Published: November 2023

Over the past decade the rapid development of cloning and sequencing technology has resulted in the identification of many genes, affording the possibility of direct analysis of gene function by gene disruption techniques. Gene cloning has also revealed that many eukaryotic enzymes, such as the major types of protein (serine/threonine) phosphatases, have several isoforms which are encoded by different genes sharing high sequence identity (1). In addition, families of related enzymes can be uncovered by this technique. Another now well-documented feature of proteins is that domains with conservation of amino acid sequence are found in different enzymes, and apparently provide these proteins with a specific property or function, for example, the calcium-binding EF-hand motif (2). The classical way of isolating genes with similar sequences or similar functional domains, is to screen a library with probes derived from one of the known DNA sequences. This method has been very successful in isolating several protein (serine/ threonine) phosphatase genes (3). However, the procedure is time consuming, particularly if there are many, new genes to be uncovered. Moreover, it may be difficult to detect genes with less overall sequence identity, even though the homology within a short region (for example, a functional domain) is significant. The polymerase chain reaction (PCR) offers a very powerful approach to isolate such genes, since it may identify many related genes in a single experiment. The overall strategy of the approach we have taken to identify many protein (serine/threonine) phosphatase (PP) genes in several different species is described in the following paragraph.
Fetal DNA analysis
Authors: Old John M
Published: November 2023

The application of molecular biology techniques to the study of genetic disease has provided a wealth of information about their molecular basis, and this knowledge has been used to establish comprehensive prenatal diagnosis programmes by fetal DNA analysis. The first prenatal diagnosis was for a0-thalassaemia in 1976 using a simple hybridization technique of an a-globin gene probe to amniocyte DNA. The discovery of restriction fragment length polymorphisms enabled sickle cell anaemia and J3-thalassaemia to be diagnosed in amniocyte DNA, but it was not until 1982 with the development of chorionic villus sampling (CVS) that prenatal diagnosis by fetal DNA analysis became widely established.
Intracellular staining in vivo
Authors: Maxwell D J
Published: November 2023

Intracellular staining techniques are unique because they provide anatomical and physiological data about individual neurones or axons. A number of staining techniques have been developed, but they all depend upon the use of recording micropipettes which contain marker substances such as horseradish peroxidase (HRP) (1, 2), Lucifer Yellow (3), or biocytin (4, 5). In this chapter it is intended to provide a detailed account of the use of HRP in intracellular staining which is arguably still the method of choice for in vivo staining in mammals, especially if the analysis is to be taken to the ultrastructural level. Methods compatible with light microscopy (LM) and combined light and electron microscopy (EM) are described.
Neuronal hybrid cell lines: generation, characterization, and utility
Authors: Wainer Bruce H , Heller Alfred
Published: November 2023

The nervous system comprises an extensive array of neuronal pathways that control and modulate virtually all bodily functions. This system develops from a simple neuroectodermal tube, and through a series of processes regulating cell division, commitment, migration, and differentiation, forms functional synaptic connections in a highly specific fashion. These processes involve internal cell programmes controlling stage-specific gene expression, cell-cell interactions, and chemical signalling. The result is an organ system of remarkable complexity, responsible for the full range of physiological and intellectual behaviour of higher organisms. A major challenge to neurobiologists is understanding the specific cellular and molecular interactions that mediate the formation and/or maintenance of functional connections between particular subsets of neurons and their target cells (1). This goal is made exceedingly difficult by the extensive heterogeneity of cell types and connections even within specific brain regions.
Generation of neural cell lines by transfer of viral oncogenes
Authors: Rouget Pierre , Bert Marc Le , Borde Isabelle , Evrard Claudine
Published: November 2023

Many aspects of the regulation of expression of genes involved in neural differentiation and cellular interactions within the nervous system remain to be elucidated. This is largely due to the difficulty of establishing phenotypically untransformed permanent neural cell lines that retain most of the functional properties of their normally differentiated cell counterparts (1). Most established neural cell lines are transformed and have lost some aspects of normal regulation of cell division and differentiation. Even though presenting transformed or tumoral characteristics, however, some of these cell lines have provided useful models of neuronal function. Such lines have been obtained from spontaneous or chemically induced tumours (2, 3), or by transformation with oncogenic viruses (4, 5). Other cell lines have been derived from embryonal carcinoma (ref. 6 and Chapter 4) or from clones proliferating spontaneously in long-term primary cultures (7).
Embryonal carcinoma cells and embryonic stem cells as models for neuronal development and function
Authors: Mccarrick James W , Andrews Peter W
Published: November 2023

For many years teratocarcinomas and their stem cells, embryonal carcinoma (EC) cells, have been well established tools for investigating cell differentiation as it relates to early embryogenesis, especially in the mouse (1, 2). More recently, lines of human EC cells have been characterized to extend this approach to human embryogenesis (3), while the isolation of embryonic stem (ES) cells (4, 5) has opened up important new approaches for the study of gene function during embryonic and fetal development. Many general aspects concerning the use of such cells were extensively covered in an earlier volume in this series (6), and the interested reader is encouraged to consult the relevant chapters of that volume for more comprehensive information. In the present chapter we shall repeat only the basic details necessary for working with these cells, and aim to supplement that earlier work with information more directly relevant to neurobiologists, and with newer techniques, such as homologous recombination and gene ‘knock-out’ experiments, which were not covered in detail previously.
Callose and Callose Synthase
Authors: Kauss Heinrich
Published: November 2023

Over the past century numerous cytochemical studies have shown that after various types of stress the polysaccharide callose is deposited, at selected sites, on to the plant cell wall. Callose mainly consists of linear 13-1, 3-glucanase (1-4), and one of its functions is to close the connections that unite protoplasts of contiguous cells(plasmodesmata, sieve pores). This process occurs within minutes of mechanical injury. Following fungal invasion there is a rapid formation (within hours) of callose-rich papillae basipetal to the sites of penetration. Such a deposition of papillae contributes to the resistance response of the host and can begin about one hour before fungal penetration pegs become visible microscopically. close formation also appears to tighten those cell wall parts neighbouring virus-induced lesions, or it can line the walls of cells that have undergone the hypersensitive response.
Embryological assays for growth factors
Authors: Slack J M W
Published: November 2023

Evidence for two classes of biologically active substance existed for many years before examples of either were purified. There were substances that promoted cell growth in tissue culture (growth factors), and there were substances that controlled the pathways of differentiation followed by cells in developing embryos (inducing factors). In recent years it has become clear that in many cases the same molecule can play both roles, and that the specificity of the biological effect depends as much on the characteristics of the responding tissue as on the identity of the factor.
Clinical HLA typing by cytotoxicity
Authors: Darke Christopher , Dyer Philip
Published: November 2023

The microlymphocytotoxicity test is universally employed for serological HLA-A, -B, -C, -DR, and -DQ typing. Peripheral blood lymphocytes (PBL) (consisting of approximately 80% T and 10-15% B cells in healthy subjects) or T cells are generally used as targets for HLA-A, -B, and -C typing. B cell enriched suspensions are used for typing HLA-DR and -DQ antigens which are not expressed on resting T cells. Lymphocytes are tested with a set of HLA specific alloantibodies which are polyclonal antisera or monoclonal antibodies (see Chapter 2) each selected to react with one (monospecific), or sometimes two or more (polyspecific/ multispecific) HLA antigens. For full HLA typing the antibody set should cover as many of the various HLA antigens as possible. Reagents for HLA typing should ideally be selected to give strong reliable positive and negative results.
Post-transcriptional regulation of human retroviral gene expression
Authors: Parslow Tristram G
Published: November 2023

The compact structure of retroviral genomes forces these viruses to rely heavily on post-transcriptional mechanisms of gene regulation. Each integrated provirus is transcribed from the single promoter in its 5’ long terminal repeat (LTR) to produce a single primary transcript that spans the entire genome. Yet, from this single transcript, the virus must express a minimum of three structural proteins (Gag, Pol, and Env) and often additional regulatory and accessory proteins as well. To express all of these products, the primary transcript must first be spliced in multiple alternative ways to generate a host of different mRNAs that specify the individual proteins. The virus must then ensure that each mRNA is delivered to the cytoplasm in appropriate amounts for translation. Moreover, unlike cellular mRNAs, retroviral mRNAs often encode two or more proteins in tandem, and so pose special problems for translation.
Analysis of Protein Folding by Protein Engineering
Authors: Matouschek Andreas , Serrano Luis , Fersht Alan R
Published: November 2023

Denatured proteins can in many cases refold to the native structure. It is generally accepted that the folding has to progress along a specific pathway (1), although Harrison and Durbin (2) have argued that folding could follow many different parallel pathways (jigsaw puzzle model). Several different models of protein folding have been proposed. The framework model (3) suggests that the earliest steps are the formation of native secondary structure elements, while an alternative model proposes that folding begins with a rapid hydrophobic collapse (4-7). A somewhat different view is reflected in the micro-domain folding models (8-10) which propose that small structural subdomains of the protein assume their native structure early during folding. These initiation sites either grow directly by extension or by diffusion and collision with other subdomains. If there are several initiation sites it is easily imaginable that many different, parallel, folding pathways exist. The molten globule hypothesis of protein folding (11, 12) suggests that a 'molten globule' intermediate occurs late on the folding pathway of all proteins. This intermediate is compact and has native-like secondary structure but fluctuating tertiary interactions. Its conversion into the native state is the rate-determining step of protein folding.
Preparation of synthetic oligodeoxynucleotide probes
Authors: Brown Tom , Grzybowski John
Published: November 2023

Detection of oligonucleotide probes can be achieved after the addition of non-radioactive reporter groups, thereby precluding the hazardous, expensive, and time-consuming introduction of radiolabels such as3H,32P,35S, and 1251. In general, high sensitivity detection can be achieved via the attachment of a hapten to the oligonucleotide. A primary antibody which binds to the hapten is added and then a secondary antibody-enzyme conjugate, specific for the primary antibody, is introduced. Typically, visualization is achieved by the addition of a substrate which reacts with the enzyme to produce a colour reaction (Figure IA). A more direct variation on this technique in volves the use of a primary antibody with a suitable enzyme already attached (Figure JB). The attachment of multiple labels or haptens has facilitated the visualization of oligonucleotide probes in quantities previously obtainable only by radiolabelling (1, 2).
Protein blotting using semi-dry electrophoretic transfer equipment
Authors: Jacobson Gunilla
Published: November 2023

Electrophoretic transfer of proteins from polyacrylamide gels to an immobilizing matrix is a widely used technique (1). When a protein is bound to a membrane it is more accessible to specific detection methods than in the gel and the separated bands are not broadened by diffusion. The technique has found wide application in detection, identification, and characterization of proteins and protein-protein interactions (2, 3). These applications are given in the remaining chapters of this text. In semi-dry electrophoretic transfer a stack of wetted filter papers surrounding the gel and the blotting membrane is used as a buffer reservoir, instead of a tank as in conventional electrophoretic transfer (4, 5).
Sample preparation for protein electrophoresis and transfer
Authors: Lee Vaughan H , Dunbar Bonnie S
Published: November 2023

A critical yet often overlooked step in the process of analysing proteins by electrophoresis and transfer is the method used for solubilization. We have found for many protein samples that the method of sample preparation is the most important consideration for optimal results with protein blotting after one-dimensional or two-dimensional polyacrylamide gel electrophoresis (PAGE). The best method for solubilization of a protein sample is dependent on the type of protein sample and the physicochemical nature of the individual proteins to be analysed. There is no one method that will give optimal solubilization and/or resolution of all proteins.
Strategy for purification of organelles from parasites: protein blotting as one of the initial steps
Authors: Sammons David W
Published: November 2023

Purification of organelles is essential for studies of the cell biology of eukaryotic cells and their parasites, and is essential for the complete understanding of the host/parasite membrane organizational and spatial interrelationships. Organelle-specific antigens or structures can be manipulated to assist in the isolation and purification of organelles; however, it is sometimes technically difficult to achieve unless consideration is made of all separation alternatives. Available principles of separation are size, density, charge, immunoaffinity, paramagnetic, and combinations of these in the presence of various buffers and detergents.
Bioluminescence-enhanced detection systems in protein blotting
Authors: Erich Geiger Reinhard
Published: November 2023

Bioluminescence is a natural phenomenon found in many lower forms of life (1-3). Naturally occurring bioluminescent systems differ with regard to the structure and function of enzymes and cofactors as well as in the mechanism of the light-emitting reactions (4, 5). Because of its high sensitivity, firefly (Photinus pyralis) bioluminescence has been used for many years for the sensitive determination of ATP (6). More recently, further highly sensitive bioluminescent and chemiluminescent methods have become available for many different analytes (7-10). Recently, bioluminescent detection of nucleic acid hybridization and protein blotting have been reported (11, 12). A new type of enzyme substrate based on luciferin derivatives, which are highly sensitive for the corresponding enzymes in the test detection systems, are described. These new substrates (13, 14) can be used for unmodified enzymes and for enzyme conjugates, applied in enzymatic activity test systems, in reporter gene tests (15), in enzyme immunoassays (16), in protein blot analysis (17, 18), and ion nucleic acid hybridization tests (12, 19).
Phagemids and other hybrid vectors
Authors: Alting-mees Michelle a. , Vaillancourt Peter , Short Jay M
Published: November 2023

In the past, gene analysis was dependent on subcloning DNA fragments between specialized vector systems. The most common step was subcloning from a plasmid or lambda cloning vector into the filamentous bacteriophage M13 for production of a single-stranded DNA template, which could then be used for sequencing by the Sanger chain termination method (1). Once the sequencing analysis was completed, the DNA fragment was subcloned into another specialized vector, such as a promoter vector designed for efficient in vitro transcription, or an expression vector for protein production.
Extrachromosomal cloning vectors of Saccharomyces cerevisiae
Authors: Sikorski Roberts S
Published: November 2023

The baker’s yeast Saccharomyces cerevisiae has become the experimental organ ism of choice for a diverse group of investigators. Sophisticated genetic techniques can be used to examine such fundamental cellular processes as cell cycle control, protein processing, gene expression, or receptor signalling. The transfer and expression of heterologous genes in yeast has provided evidence that many of these processes share mechanisms conserved throughout evolution.
Photosynthesis research: aspects and perspectives
Authors: Herrmann Reinhold g.
Published: November 2023

Biological photosynthesis, that is, the conversion of solar energy into high-energy chemical metabolites (ATP, NADPH, and carbohydrates), is globally the most fundamental biochemical process. It provides energy, organic matter, and oxygen for nearly all biotic processes, and it is the only renewable energy source of our planet. Life in its present form depends on it. The conversion of solar to chemical energy, which in oxygenic photosynthesis is accompanied by the evolution of molecular oxygen, is catalysed by thylakoid membranes that are found in prokaryotic cells and in the photosynthetic organelles (chloro-, rhodo-, phaeoplasts, etc.) of eukaryotic cells. Because of the capability of that energy conversion, thylakoid membranes occupy a unique position among biomembranes. Additional aspects of photosynthetic energy metabolism appeared with the advent of, and the concomitant division of labour in, multicellular eukaryotes. The tissues of the complex cellular societies of thallophytes, bryophytes, and vascular plants, each assigned a limited range of functions essential to the healthy operation of the community, are involved in fundamental biological processes intimately related to photosynthesis, such as carbohydrate transport, or carbohydrate and lipid storage. Various photosynthetic specialists appeared at this level. Many of these advanced processes operate with distinct plastid variants, e.g. bundle sheath chloroplasts, amyloplasts, or elaioplasts.
Immunization with peptide—carrier complexes: traditional and multiple-antigen peptide systems
Authors: Tam James P
Published: November 2023

Among various strategies for immunization, the strategy of using synthetic peptides is perhaps the most appealing, both in conceptual simplicity and in practical convenience (1-10). It is a minimalist approach that uses a peptide segment with one or a few of the desired epitopes of a protein or whole organism, both of which are many times larger than the peptide. By keeping only the essential epitope(s) and eliminating all other, unwanted, portions of the protein or organism, a synthetic peptide immunogen provides, in theory, the desired selectivity. Advances in solid-phase synthesis have made the preparation of peptides a routine task in most laboratories. In addition, access to synthetic peptides has been made easy by the proliferation of core facilities in universities and of commercial laboratories specialized for the preparation of peptides to order. Thus, the use of synthetic peptides has become a well accepted method for the preparation of site-specific antibodies for various biochemical and functional studies.
Non-isotopic detection of nucleic
acids on membranes
Authors: Hughes J R , Evans M F , Levy E R
Published: November 2023

Membrane-based methods of DNA and RNA analysis have traditionally relied on the use of radiolabelled probes. Whilst they offer a robust and sensitive system there are associated problems involving the instability of the isotope, the requirement for designated laboratory areas and equipment for the handling of the isotope, and the specialist removal of waste. These problems have led to the development of a number of non-isotopic techniques for the analysis of nucleic acids that are sensitive enough to detect unique copy sequences within genomic digests. Non-isotopic alternatives are classified into two categories (indirect and direct) depending on the method of labelling the probe. The majority of systems available for filter assays involve indirect detection of a labelled probe in several stages (Figure 1):a. Label the sequence b. Hybridize the sequence to membrane-bound nucleic acid. c. Detect nucleic acid: probe hybrids via the specific binding of a nonradioactive reporter system.
Agar from Namibian Gracilaria spp
Authors: Gidley Michael J , Hedges Nicholas D , Hoffmann Rainer A , Dawes Christopher P
Published: November 2023

Agar has a long history of use as a food ingredient in East Asia (1), but has traditionally found application only in niche markets in Western foods. However, with increasing emphasis on food ingredients with both high functionality and a history of traditional use, it is envisaged that the global utilisation of agar as a food ingredient will increase in the future (2,3). This will require a greater understanding of the nature of agar polymers extracted from various potential algal sources, and improved knowledge of the relationship between molecular structure and functional properties.
Shapes and sizes of food polysaccharides by sedimentation analysis-recent developments
Authors: Harding Stephen E
Published: November 2023

Knowledge of the fundamental behaviour of food polysaccharides on a “microscopic” scale (in terms of their sizes. shapes, molecular weight distribution and interaction parameters) in dilute and concentrated solution form - both by themselves and in mixtures - is important for the proper understanding of their behaviour in food products on a “macroscopic” scale (such as gelling, thickening ability and phase separation). This information can help us choose the “right” polysaccharide with the “right” properties for a particular product.
Performance characteristics of some synthetic emulsifiers
Authors: El-Shattory Y , Aly Saadia M , Megahed M G
Published: November 2023

Many of our foods are emulsions. The commonly recognized ones are milk, butter, mayonnaise, salad dressings, gravies, and ice cream. Some of the other easily recognized emulsions and foods in which emulsions are an important step in production are beverages, cakes, candy, frostings, marshmallow, condiment preparations, shortening, margarine, pickles, flavoring oils, yeasts and eggs (1).
Shear hardening of gellan gum gels
Authors: Tsiami A , Morris V J , Brownsey G J
Published: November 2023

Gellan gum is a bacterial polysaccharide that is marketed as a broad spectrum gelling agent. It has received food approval in Japan, limited FDA approval for food use in the USA and approval is being sought for food application in the UK and EC. Preliminary rheological studies of aqueous gellan gels at low ionic strength showed consistent elastic properties, these becoming increasingly variable with increase in ionic strength. Stress relaxation experiments were chosen to examine the mechanical behaviour of the gels and provide a possible explanation of these effects. At low ionic strength, the gels approximate to elastic gels whereas at high ionic strength the increased stress relaxation behaviour resembles that shown by colloidal-like systems. However, unlike colloidal systems, when the gels were subjected to successive applications of stress, the magnitude of the stress relaxation decreased and the relaxation modulus increased, indicative of a shear hardening phenomenon. Interpretation in terms of a heterogeneous nature of the gels has implications for such textural properties as flavour release.
Recent advances in the rheological characterisation of gelatin gels
Authors: Ross-Murphy S
Published: November 2023

In the last few years significant progress has been made in the study of gelatin gels and gelation. Indeed the previously accepted view, wherein initial renaturation of the collagen-like triple helix was followed by substantial aggregation to a “fringed micelle” structure, has been shown not to be consistent with the measured cross-sectional radius of gyration, nor with the increase in optical rotation and modulus on a log time axis. These results are reviewed; they suggest that gelatin gels involve a rubber-like network. Rheological data are consistent with this view. Results presented below for the concentration dependence of gel modulus agree well with an ideal branched chain model, with no independent parameters. In separately deducing these parameters we have exploited data from a number of other (non-rheological) experiments carried out by other workers.
Tailor-made pectins for specific influencing of the sensory rheological properties of preserves, jams, jellies, marmalades and other jellified products
Authors: Kratz Evamarie
Published: November 2023

The increasing quality demand on jams, jellies and marmalades is not limited on gel strength but also includes consistency, texture and syneresis behaviour. The optimum consistency for the consumer may vary from country to country and product to product. In some countries the consumer may prefer very firm, brittle gels for some products, in other countries an especially soft and spreadable gel texture (Swiss Consistency) is requested. In general an extra jam is required to show a firmer consistency than a fruit dessert or a fruit spread.
Biotechnology for the improvement of malting barley
Authors: Mannonen Leena , Kurten Ulrika , Ritala Anneli , Salmenkallio-Marttila Marjatta , Hannus Rütta , Aspegren Kristian , Teeri Teemu , Kauppinen Veli
Published: November 2023

A method for the transformation of barley has been developed. The first application of this method for the genetic improvement of malting barley quality is the transfer of a gene coding for thermostable B-glucanase that enhances modification of the malt and helps towards a trouble-free brewing process. In the first phase research has been focused on barley cell culture technology and on development of the gene transfer methods.
Resorufin-labelled casein as a substrate for protease activity in beer
Authors: Mochaba F , Torline P A , Axcell B
Published: November 2023

A simple and sensitive assay for yeast proteolytic activity has been developed using resorufin-labelled casein as a substrate. Pitching yeast propagated in a brewery produced high levels of extra-cellular protease activity in the wort at all stages throughout fermentation. On the other hand, yeast propagated under “ideal” laboratory conditions showed only minimal extra-cellular protease activity during laboratory 2 1 fermentation. Although yeast excretes a certain amount of proteolytic activity even during active periods of growth, higher levels are secreted when cell growth declines or on death. The assay can be used as a measure of yeast suitability for pitching.
The application of membranes for new approaches to brewery operations
Authors: Bühler T M , Burrell K , Eggars H U , Reed R J R
Published: November 2023

Crossflow filtration of beer through low cost ceramic membranes is economically attractive. Frequent and rapid cleaning maintains satisfactory flux. A pore size of 0.5 µm gives a bright, near-sterile product without any loss of beer components. A pore size of 1.3 µmis suited to bottoms filtration. Crossflow filtration of wort from mash using membranes is achieved using two stages: coarse separation followed by polishing, enabling reduced plant size and cost. Hydrophobic PTFE membranes can be used to remove excess dissolved co from beer. co fluxes as high as 6.2 kg/m 1.h have been achieved.
Assembly, post-translational processing, and subcellular localization of ion channels
Authors: Millar Neil S , Moss Stephen J , Green William N
Published: November 2023

Most ion channels are complex, multi-subunit transmembrane proteins (1-3). Aconsequence of this structural complexity is that the correct functional expression of ion channels requires a diverse series of post-translational events including covalent modifications and subunit oligomerization. After protein synthesis and translocation into the endoplasmic reticulum (ER) membrane, newly-synthesized transmembrane polypeptides may undergo a variety of post-translational modifications (such as proteolytic cleavage, phosphorylation, glycosylation, fatty acylation, and disulphide bond formation). Individual polypeptides must also fold correctly into their native conformation and, in many cases, multiple polypeptide subunits must be accurately assembled into multi-subunit ion-channel complexes. Finally, the modified and assembled ion channels must be delivered to their appropriate subcellular location. Clearly, these subunit folding and oligomerization events must be carried out with great accuracy if ion channels are to perform their appropriate physiological function. How the processing, assembly, and subcellular localization of ion channels is achieved with sufficient accuracy is clearly of great interest and significance and has been the subject of a great deal of recent research.
Astrocytes
Authors: Marriott Derek R , Hirst Warren D , Ljungberg M Cecilia
Published: November 2023

The close anatomical association between astrocytes and neurons has long been suggestive of some functional interplay between these cells. However, the structural complexity of the CNS has often precluded definitive studies of astrocytes in vivo. As a consequence the elucidation of their functional properties has relied, almost entirely, on tissue culture techniques. Cultured astro cytes are easily accessible to experimental manipulation and can now be routinely prepared with greater than 95% homogeneity.
Microglia: the tissue macrophage of the CNS
Authors: Woodroofe M Nicola , Cuzner M Louise
Published: November 2023

Microglia are distinct from neurons and macroglia and are of probable mesodermal origin. Monocytes/macrophages infiltrate the central nervous system (CNS) during development and in the adult animal take on the ramified morphology of resting microglia, no longer expressing the full complement of macrophage markers (1). Microglia are present in all brain areas but are not uniformly distributed, being enriched in grey matter (2). In the mouse brain the proportion varies from 5% in the cortex to 12% in the substantia nigra. The morphology of microglia in vivo varies according to their location and microenvironmental factors and ranges from compact amoeboid cells to ramified, branched cells, with considerable variation in the length and complexity of branching of the processes. Their plasticity is emphasized by their rapid morphological changes in response to mechanical or pathological insults.
Virological and molecular genetic techniques for studies of established HIV isolates
Authors: Peden Keith W C , Martin Malcolm A
Published: November 2023

In this chapter we describe the methods commonly used for the preparation of HIV stocks from cell culture systems, their propagation in tissue culture, assays to measure virus production, and the quantification of virus infectivity. In addition, we shall discuss approaches used for the isolation and construction of infectious molecular clones of HIV, and the manipulation of these clones to introduce mutations. We do not intend that this will be an exhaustive survey of the methods used, and the ones included obviously reflect the bias and experience of the authors.
Vectors based on HIV
Authors: Richardson J H , Lever A M L
Published: November 2023

Retroviral vectors based on murine and avian retroviruses are widely used as an efficient method of gene transfer into mitotic cells (1). They have the advantages of: stable, single copy gene insertion into a host cell chromosome minimal toxicity and cytopathicity targeted gene transfer into cells bearing the appropriate viral receptor suitability for use in vivo Recently, retroviral vector technology has been taken into clinical use with Moloney murine leukaemia virus (M-MuLV) vectors being used as the mode of gene delivery in the first trials of human gene therapy. Vectors derived from HIV-1 have been developed not only as a vehicle for foreign gene transfer but also as a tool to study genomic RNA encapsidation (2), virus replication (3), and cell entry (4, 5). Specific advantages of a vector system based on HIV include:
Quantitative assays for virus neutralization
Authors: Mckeating Jane
Published: November 2023

Introduction

Neutralizing antibodies provide one of the main host defences against viral infection. They are associated with protective immunity resulting from successful vaccination against numerous viruses, including vaccinia, poliomyelitis, measles, rubella, adeno, and rabies. However, the mechanisms by which antibodies neutralize viral infection are generally not well understood. The block to infection may occur at the level of viral-receptor interaction or at one of many events leading to viral fusion and entry (1).
lymphocyte and ADCC responses
Authors: Gotch Frances , Broliden Kristina
Published: November 2023

Infection with HIV-1 (or HIV-2 or SIV) induces initial and long-lasting high levels of MHC class I restricted CD8-positive cytotoxic T lymphocytes (CTL) which interact through their specific T cell receptors (TCRs) with processed viral fragments (peptides) presented on the surface of infected cells in association with an MHC molecule (1). Infected cells are thus destroyed. CTL have been demonstrated against most of the HIV-1 gene products including gag, pol env, nef, and vif (2). CTL have mostly been studied using peripheral blood lymphocytes (PBL), but they have also been isolated from infected organs such as lungs (3), lymph nodes (4), and the central nervous system (CNS) (5). There appears to be a progressive decline in HIV-specific CTL activity which parallels the development of HIV-related disease (4). The measurement and identification of the activity, specificity, and frequency of HIV-specific CTL, and their variation with time, may indicate their relative importance in modulating HIV infection. Identification of CTL epitopes is also essential for subunit vaccine design.
Reverse transcriptase
Authors: Beard W A , Wilson S H
Published: November 2023

The reverse transcriptase (RT) of human immunodeficiency virus type-1 (HIV-1) converts the single-stranded (+) viral RNA genome into double¬ stranded proviral DNA prior to its integration into the host genomic DNA. The HIV-1 RT has therefore been the target for anti-viral drug design (1). The cloning of the RT in biologically active form has made large quantities of enzyme available for biophysical and kinetic studies. In vivo, the heterodimeric form (p66/p51) of RT is believed to be the result of carboxy-terminal proteolytic cleavage of one subunit of the homodimer (p66/p66) (2). Crystal structures of RT complexed with DNA (3) and a non-nucleoside inhibitor (4) have recently been published. In addition, pre-steady state kinetic studies are now available (5- 7). This detailed structural and kinetic information is pro¬ viding the prerequisite information for rational drug design of specific and potent inhibitors.
Transient assay for Nef-induced down-regulation of CD4 antigen expression on the cell surface
Authors: Skowronski J , Mariani R
Published: November 2023

The nef genes of the human and simian immunodeficiency viruses encode closely related proteins of 25 kDa to 27 kDa which are expressed in the cytoplasm of virally-infected cells. Nef is essential for SIV pathogenesis in the rhesus monkey model of human AIDS (1) but does not appear to be required for viral growth in vitro. As a result, nef genes of many commonly studied viral isolates are truncated prematurely, or contain loss-of-function alleles. Recent observations from several laboratories indicate that a large fraction of nef alleles derived from either laboratory HIV and SIV isolates, or cloned directly from peripheral blood leucocytes of HIV-infected patients, are able to decrease CD4 antigen expression on the cell surface. This effect of nef on CD4 expression is neither species-, nor cell type-specific. CD4 downregulation has been documented in both human and murine CD4-positive T cells, and in non-lymphoid cells expressing endogenous, or transfected, CD4 genes (2-6). The CD4 antigen is required both for the normal development and function of helper T cells, and to mediate immunodeficiency virus infection (7). Thus, the interaction of nef with CD4 is likely to have profound, yet mostly unexplored, consequences for the HIV-I-infected CD4-positive T cell.