bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of development and differentiation with tumour cell glycoproteins
Authors: Koch Gordon , Smith Michael 
Published: February 2005

AbstractThe repertoire of acceptor glycoproteins for concanavalin A expressed by a cultured tumour cell reflects the normal developmental lineage from which it was derived, as well as the degree of maturation along that lineage. Antibodies to this particular set of glycoproteins show a considerable specificity towards normal differentiation antigens which are often preferentially associated with the less mature intermediates of the corresponding pathway. In addition, comparisons between ‘immature’ and ‘mature’ tumour cells can be used to identify glycoproteins associated with specific differentiated functions such as secretion. Thus tumour cell glycoproteins provide useful probes for analysis of the molecular biology of development and differentiation.
Transposon‐induced events at gene loci
Authors: Peterson Peter A. 
Published: February 2005

AbstractIn the October issue of BioEssays (vol. 3, no. 4), H. P. Döring reviewed the general molecular biology of transposable elements in plants. In this review by P. A. Peterson, the effects of transposable genetic elements are considered, with special attention being paid to investigation of mobile‐element‐induced mutations at loci that control identifiable enzymes, and the specific alterations in enzyme properties that result. Together with DNA sequence analysis, these studies have begun to reveal the complexity of insertion/excision events, and their potential in protein evolution.
Using molecular mimicry to produce anti‐receptor antibodies
Authors: Linthicum D. Scott , Bolger Michael B. 
Published: February 2005

AbstractAn innovative approach to the production of anti‐receptor antibodies is now being fully exploited for a number of different cell receptors. This approach employs the concept that antibodies directed against pharmacologically active ligands have a three‐dimensional binding site which is somewhat analogous to the natural receptor. Consequently, when anti‐idiotype antibodies are produced against these anti‐ligand antibodies, some of the anti‐idiotypes will comprise a positive three‐dimensional shape which mimics the original ligand. The anti‐idiotypic antibodies generated in this fashion are able to bind to cell surface receptors. This approach has now been successfully applied to peptide hormones, small bio‐active peptides, interferon, viral hemagglutinins, and a number of small neurotransmitter ligands. So far, the boundaries for this working ‘molecular engineering’ concept have not been reached. This concept may also shed light on the processes which take place in the generation of anti‐receptor antibodies in several autoimmune diseases.
Roots: Activated intermediates: The unexpected may sometimes carry a message
Authors: Lipmann Fritz 
Published: February 2005

AbstractIn this Roots essay, Fritz Lipmann reviews the ways in which a number of activated metabolic intermediates were discovered, and where, not infrequently, he himself played a leading role. The concept of ‘squiggle‐P’ (∼ P) to denote the controversially named ‘high‐energy bond’, the discoveries of acetylphosphate, the activation of carboxylic acids and of amino acids, and of acetyl coenzyme A, are reviewed. In addition, carbamoyl phosphate as perhaps the earliest activated phosphate donor to evolve, and active sulfate, in phosphoadenosine phosphosulfate, are discussed, as well as the remarkable earlier discovery by Buchner and Hahn of how to prepare a yeast extract that fermented carbohydrate to ethanol; this discovery is viewed by Lipmann as the opening chapter in the new sciences of biochemistry and molecular biology.
Transforming mutations in protein—tyrosine kinase genes
Authors: Cooper Jonathan A. 
Published: February 2005

AbstractOncogenes are altered forms of normal cellular genes known as proto‐oncogenes. Several oncogenes encode enzymes that phosphorylate substrate proteins at tyrosine. In most of these cases the oncogene differs from its proto‐oncogene by multiple mutations that alter the structure of the encoded protein product. Here we discuss how structural changes might effect the regulation and substrate specificity of the protein kinase product of a protooncogene so that it gains the potential to transform cells.
The molecular biology of the polycyclic aromatic hydrocarbon inducible cytochrome P‐450; the past is prologue
Authors: Iversen P. L. , Hines R. N. , Bresnick Edward 
Published: February 2005

AbstractThe heme‐containing cytochromes P‐450 are a ubiquitous family of monooxygenase isozymes responsible for the oxidative metabolism of a wide variety of endogenous as well as exogenous compounds. Many of the compounds metabolized by this enzyme system are effectively detoxified and converted to derivatives more easily eliminated from the organism. However, some compounds can be activated to reactive species capable of eliciting a cascade of toxic lesions, including cancer. Since its discovery nearly 30 years ago, the cytochrome P‐450 enzyme system has received a great deal of attention, particularly in the areas of their mechanisms of metabolism, range of substrate specificity, the purification and characterization of the multiple isozymes and, more recently, the regulation of expression of specific forms. This review will discuss current notions concerning the expression of at least one cytochrome P‐450 isozyme and future directions that should lead to a more complete understanding of cytochrome P‐450 gene expression in general, particularly as it impacts upon biochemical pharmacology.
Inborn errors of GABA metabolism
Authors: Gibson Kenneth M. , Nyhan William L. , Jaeken Jaak 
Published: February 2005

AbstractDefects in man in four steps of 4‐aminobutyric acid (GABA) metabolism may interefere with the function of this major inhibitory neurotransmitter. Glutamic acid decarboxylase, 4‐aminobutyric acid aminotransferase, succinic semialdehyde dehydrogenase, and homocarnosinase are closely identified with the brain, but two of these enzymes are expressed in cultured peripheral cells, which may permit novel approaches to the study of the metabolism and regulation of GABA.
Trichothecenes and yellow rain: Possible biological warfare agents
Authors: Dashek W. V. , Mayfield J. E. , Llewellyn G. C. , O'Rear C. E. , Bata A. 
Published: February 2005

Abstract‘Yellow Rain’, an alleged biological warfare agent thought to be utilized in parts of both South East Asia and Afghanistan, may be composed in part of the mycotoxins, trichothecenes. However, more recent analyses suggest that the ‘Rain’ was mainly honey bee excreta. The history of the controversy together with the biological effects, chemistry as well as the fungi producing these mycotoxins and agricultural commodities affected by trichothecenes are reviewed.
What the papers say: Trisphosphoinositol as the intra‐myonal signal messenger, crucial in excitation‐contraction coupling in muscle
Authors: Mommaerts W. F. H. M. 
Published: February 2005

AbstractEvidence is reviewed here that inositol (1, 4, 5) trisphosphate (Ins P3) is a key signal in translating the electrophysiological event in muscle stimulation into the molecular‐mechanical events of contraction. Not least, these findings raise questions about the suitability of the term ‘second messenger’.
Catalysis by RNA
Authors: Waugh David S. , Pace Norman R. 
Published: February 2005

AbstractUntil the discovery of catalytic RNA, the notion that all enzymes are proteins had seemed incontrovertible. Now the existence of RNA enzymes has been confirmed in a variety of contexts. What is known about the chemistry of RNA‐catalyzed reactions is reviewed below, with particular attention to the self‐splicing rRNA intron of Tetrahymena thermophila and the processing of pre‐tRNA molecules by RNase P.
Human choriogonadotropin
Authors: Puett David 
Published: February 2005

AbstractHuman choriogonadotropin, a hormone derived from the syncytiotrophoblast cells of the placenta, is a member of the glycoprotein hormone family which also contains the pituitary hormones lutropin, follitropin and thyrotropin. These four hormones are comprised of two dissimilar subunits, one (α) being common to all four and the other (β) conferring hormonal specificity. Information is rapidly accumulating on the nature and regulation of the genes for these subunits, as well as the structural aspects, mechanism‐of‐action and physiological roles of these complex hormones. This mini review considers some of the recent advances in our understanding of human choriogonadotropin.
Structural analysis of a yeast centromere
Authors: Bloom Kerry , Hill Alison , Yeh Elaine 
Published: February 2005

AbstractThe most striking region of structural differentiation of a eukaryotic chromosome is the kinetochore. This chromosomal domain plays an integral role in the stability and propagation of genetic material to the progeny cells during cell division. The DNA component of this structure, which we refer to as the centromere, has been localized to a small region of 220–250 base pairs within the chromosomes from the yeast Saccharomyces cerevisiae. The centromere DNA (CEN) is organized in a unique structure in the cell nucleus and is required for chromosome stability during both mitotic and meiotic cell cycles. The centromeres from one chromosome can stabilize small circular minichromosomes or other yeast chromosomes. The centromeres may therefore interact with the same components of the segregation apparatus regardless of the chromosome in which they reside. The CEN DNA does not encode any regulatory RNAs or proteins, but rather is a cis‐acting element that provides genetic stability to adjacent DNA sequences.
Endocytosis and epithelial biogenesis in the mouse early embryo
Authors: Fleming Tom P. 
Published: February 2005

AbstractThe polarized organization of epithelial cells is expressed in many ways including the morphology of the cell surface or cytocortex, the molecular composition of membrane domains and the distribution of cytoplasmic organelles. The differentiation of mouse trophectoderm is described with particular attention given to the maturation of the endocytic system in an attempt to define how the complex assembly of an epithelium may be generated.
Cell‐surface receptors: Puzzles and paradigms
Authors: Geisow Michael J. 
Published: February 2005

AbstractThe determination of amino acid sequences representing the cell‐surface receptors for transferrin,1 asialoglycoprotein,2 polymeric immunoglobulin (IgA/IgM),3 epidermal growth factor (EGF),4 lowdensity lipoprotein (LDL)5 and insulin6 has produced new paradingms for receptor architecture. This review examines common features of the protiens and describes the intriguing functional and evolutionary puzzles that have arisen from them.
Cell interactions in the developing leech embryo
Authors: Bissen Shirley T. , Ho Robert K. , Weisblat David A. 
Published: February 2005

AbstractThe stereotyped pattern of cell commitments during leech embryogenesis is described. The nature of cell commitments during segmentation differs significantly between leech and fruit fly. Despite the constancy of cell fate assignments in normal development, ablation experiments show that cell interactions are essential in setting some of these commitments. Interacting cells follow a positionally determined hierarchy of fate choices. For other cells, which appear to have fates fixed from birth, the possibility of determinative interactions between mother and daughter cells is discussed.
What regulates secretion of non‐stored proteins by eukaryotic cells?
Authors: Gebhart Ann Marie , Ruddon Raymond W. 
Published: February 2005

AbstractProtein secretion is conventionally viewed as taking place by either of two cellular routes, a regulated pathway, involving external stimuli and secretory granules, and a presumptive ‘constitutive’ pathway, which does not involve hormonal or neuronal stimuli or the production of secretory granules. The evidence reviewed here strongly suggests that there are post‐synthesis rate‐limiting steps for many proteins released by the ‘constitutive’ pathway and, hence, that regulation in some sense is involved here too. The nature of these rate‐limiting determinants and events is discussed.
Pathways of human T lymphocyte development and activation
Authors: Alcover Andres , Milanese Claudio , Reinherz Ellis L. 
Published: February 2005

AbstractThe T lymphocyte receptor for antigen, which operates in conjunction with gene products of the major histocompatibility complex (MHC), is a molecular complex comprised of five polypeptide chains. Both the 49 kDa alpha and 43 kDa beta chains are immunoglobulin‐like and thus contain variable domains responsible for ligand binding. In contrast, the 20–25 kDa T3 gamma, delta and epsilon chains are monomorphic structures presumably involved in transmembrane signalling. The alpha and beta subunits are disulfide bonded to each other and held in noncovalent association with the T3 chains. T3‐Ti receptor crosslinking leads to conformational modification of a second T lineage specific molecule, termed the 50 kDa T11 structure which in turn leads to protein kinase C activation, elevation in intracytoplasmic free calcium and Na+/H+ antiport stimulation.
Roots: Why affinity progression of antibodies during immune responses is probably not accompanied by parallel changes in the immunoglobulin‐like antigen‐specific receptors on T cells
Authors: Eisen Herman N. 
Published: February 2005

AbstractThere can be no doubt that a closer study of avidity will be an indispensable step towards understanding the mechanisms of immunity. N. K. Jerne, 1951, p. 1403.
Problem and paradigms: Somatic generation of a genetic polymorphism: Towards the solution of the I‐J Enigma
Authors: Tada Tomio , Asano Yoshihiro 
Published: February 2005

AbstractI‐J has been regarded as a polymorphic genetic marker controlled by a locus in the major histocompatibility complex (MHC) which is expressed only on functional T cells. However, this antigenic determinant has been found not to be directly encoded by the MHC gene per se but is somatically generated according to the MHC of the cellular environment during ontogeny. This explains the apparent linkage of I‐J to MHC, despite the failure to find the structural gene for I‐J within the MHC. The I‐J paradox provides an instance of a polymorphism that does not follow the standard genetics of Mendelian structural genes.
Spectrin subtypes in mammalian brain
Authors: Goodman Steven R. , Riederer Beat M. , Zagon Lan S. 
Published: February 2005

AbstractMammalian neural cells contain at least two forms of brain spectrin: brain spectrin (240/235) which is located primarily in the axons and presynaptic terminals of neurons, and brain spectrin (240/235E) which is found in the cell bodies, dendrites and postsynaptic terminals of neurones. Brain spectrin (240/235E) is also found in certain glial cell types. Antibodies against red blood cell spectrin detect only brain spectrin (240/235E), while antibodies against brain spectrin isolated from axonal and synaptic membranes detect brain spectrin (240/235). Previous apparent discrepancies in the literature concerning brain spectrin localization at the light microscope level were undoubtedly due to different laboratories detecting distinct brain spectrin subtypes, based on the particular antibody being utilized for immunohistochemistry. In this review we (1) discuss the data supporting the presence of at least two distinct subtypes of mammalian brain spectrin, (2) explain how these results reconcile previous discrepancies concerning the localization of spectrin within neural cells, and (3) suggest the future implications of these findings.
Molecular aspects of atrial natriuretic peptides
Authors: Imamura Toshiko , Miura Yoshiaki 
Published: February 2005

AbstractPeptides possessing both natriuretic and smooth muscle relaxant activities have been isolated from heart atria and their structures have been determined. The peptides designated ANP (atrial natriuretic peptide) regulate salt and water balance and blood pressure. The scope of this article is to provide a summary of recent research developments directed towards understanding the molecular nature of atrial natriuretic peptides.
The amdS gene of Aspergillus nidulans: Control by multiple regulatory signals
Authors: Hynes Michael J. , Davis Meryl A. 
Published: February 2005

AbstractThe amdS gene of A. nidulans has proved extremely favourable for the isolation of mutations affecting gene regulation. Trans‐acting regulatory genes involved in amdS induction by small molecular weight effectors have been identified – amdR (ω‐amino acids) facB (acetate) and amdA (acetate). Another gene, the areA gene, has properties expected of a major activator gene involved in nitrogen metabolite repression of amdS. All of these regulatory genes are also involved in the control of various other functions encoded by structural genes unlinked to amdS. Mutations in the 5′‐region adjacent to amdS have been isolated and allow the identification of independent cis‐acting sequences which are the target sites for the regulatory genes. The involvement of these sequences in regulatory product binding has been deduced from titration studies using transformants containing multiple copies of the 5′ sequences. A combination of genetics and molecular analysis is allowing a detailed characterization of this system.
The replication of cowpea mosaic virus
Authors: Van Kammen A. , Eggen H. I. L. 
Published: February 2005

AbstractCowpea mosaic virus (CPMV) is the type member of the comovirus group, which contains 14 different plant viruses that have the same structural organization of genomic RNAs and virions and use the same mechanism for expression of the viral RNAs. The combined structure and organization of the two CPMV genomic RNAs is strikingly similar to that of the single genome of animal picornaviruses. This suggests a common ancestry and similar replication mechanisms. CPMV is by far the best‐studied comovirus and we shall limit this review to some recent data on this virus. For additional general information the reader is referred to other recent reviews on CPMV and comoviruses1,2.
Retinoblastoma – genetic insights into neoplasia
Authors: Nyhan William L. 
Published: February 2005

AbstractRetinoblastoma is a highly malignant ocular tumor that has been known to be hereditary in some instances. New information from cytogenetic and molecular studies indicates that there is a retinoblastoma gene and that the mutant alleles are recessive. The wild‐type gene appears to be a suppressor of this neoplasia, and, when both alleles are lost, malignancy develops.
Drosophila segmentation genes and blastoderm cell identities
Authors: Gergen J. Peter 
Published: February 2005

AbstractThe formation of the segmentation pattern in Drosophila embryos provides an excellent model for investigating the process of pattern formation in multicellular organisms. Several genes required in an embryo for normal segmentation have been analyzed by classical and molecular genetic and morphological techniques. A detailed consideration of these results suggests that these segmentation genes are combinatorially involved in translating the positional identities of individual cells at an early stage in Drosophila development.
The lin‐12 locus of Caenorhabditis elegans
Authors: Greenwald Iva 
Published: February 2005

AbstractAnalysis of the patterns of cell lineage observed during development of the nematode Caenorhabditis elegans, combined with selected cell ablation experiments, has revealed that while many cell fates are autonomously (intrinsically) determined, cell–cell interactions are required for a number of developmental decisions. Earlier genetic analysis of one key gene, lin‐12, had shown that this gene controls a number of bi‐potential fate decisions involving such cellular interactions. Molecular analysis of this gene is now providing clues to its mode of action in mediating these cell‐fate decision.
Overcoming random diffusion in polarized cells – corralling the drunken beggar
Authors: Wolf David E. 
Published: February 2005

AbstractCells are capable of overcoming the randomizing effect of lateral diffusion in order to regionally differentiate their surfaces. Such local structural specializations are of major significance to cellular function. In some cases, they may be explained by diffusion rates that are insufficient to completely randomize surface gradients over biologically relevant times scales. However, in other cases, absolute and permanent regionalizations are also observed. Mechanistically, the problem is analogous to equilibrium across a dialysis bag: either an absolute barrier exists or the chemical potential between two adjacent regions must be equal. The interactive nature of the system, where localizations of one component lead to localization of others, are also considered here.
Biodegradation of environmental pollutants by the white rot fungus Phanerochaete chrysosporium: Involvement of the lignin degrading system
Authors: Bumpus John A. , Aust Steven D. 
Published: February 2005

AbstractThe white‐rot fungus Phanrochaete chrysosporium has the ability to degrade a wide variety of structurally diverse organic compounds, including a number of environmentally persistent organopollutants. The unique biodegradative abilities of this fungus appears to be dependent upon its lignin‐degrading system. The non‐specific and partially extracellular nature of this system suggests that it may be useful as a supplementary means to treat organochemical wastes.
Branched RNA
Authors: Edmonds Mary 
Published: February 2005

AbstractThe only RNA molecules known to be branched are circular structures with tails known as lariats that arise during nuclear pre‐mRNA splicing. Lariats accumulate within a large multicomponent particle called a spliceosome that forms upon the addition of unspliced mRNA to nuclear extracts. Recently an RNA molecule has been observed to catalyze branch formation. In this case a single intron of a yeast mitochondrial pre‐mRNA participates in a self‐splicing reaction that results in the accumulation of branched lariats that are processed to correctly spliced exons.An enzyme highly specific for branch removal found in the same extracts that form branches during pre‐mRNA splicing can debranch RNA lariats to their linear forms without loss of nucleotides.The chemical synthesis of branched RNA has recently been achieved. High yields of sequence‐specific oligonucleotides are now available for the analysis of RNA splicing by techniques dependent on branch‐site recognition.
Regulation of messenger RNA stability in eukaryotic cells
Authors: Shapiro David J. , Blume John E. , Nielsen David A. 
Published: February 2005

AbstractRegulation of the cytoplasmic stability of mRNAs has recetly been identified as a major control mechanism which governs mRNA levels in a variety of eukaryotic systems. In this review we discuss what is known about several experimental systems that exhibit regulated mRNA stability, describe the mechanisms that cells may use to achieve control of mRNA degradation, and suggest areas of future investigation likely to provide new insights into this process.
The screening of enzyme‐targeted drugs
Authors: Tsou C. L. 
Published: February 2005

AbstractIn this article C. L. Tsou, of the Institute of Biophysics, Beijing, criticizes the use of the expression I50, the inhibitor concentration to produce 50% inhibition of a particular enzyme as a ‘most unfortunate’ parameter, when screening enzyme inhibitors designed as drugs. Comments on Dr Tsou's point of view will be welcomed from readers.