bluuebunny/crossref_metadata_2025_split huggingface dataset:
Problems and paradigms: Physiological analysis of bone appetite (Osteophagia)
Authors: Denton D. A. , Blair‐West J. R. , McKinley M. J. , Nelson J. F. 
Published: February 2005

AbstractThe vegetation eaten by animals on large areas of several continents is deficient in phosphate and deleterious effects on physiology, particularly reproduction, ensue. Records on bone chewing behaviour by both pastoral andwild game animals extend over two centuries. In laboratory investigation of this apt behaviour it has been shown that the appetite for bones is innate and specific and cued predominantly by olfactory stimuli. It is suppressed by rapidly increasing the plasma phosphate concentration to normal but not influenced by increasing the phosphate concentration in cerebrospinal fluid. The central organization of this genetically programmed behaviour appears to differ from systems subserving thirst and sodium appetite.
The elucidation of the human mitochondrial genome: A historical perspective
Authors: Attardi Giuseppe 
Published: February 2005

AbstractThe progressive unraveling over the past fifteen years of the structure and function of the human mitochondrial genome, taken as a prototype of all vertebrate mitochondrial genomes, has been marked by a series of startling discoveries. The history of these developments is one in which prediction often turned out to be wrong, and in which solidly established dogmas were violated. The unique features of this genome have forced a revision of our ideas about the universality of the genetic code and of the decoding mechanism, the minimal structural requirements for rRNA, tRNA and mRNA function and the mode and control of gene expression.
Cell migrations during morphogenesis: Some clues from the slug of Dictyostelium discoideum
Authors: Williams Keith L. , Vardy Phil. H. , Segel Lee A. 
Published: February 2005

AbstractStarvation induces free‐living Dictyostelium discoideum amoebae to form slugs that typically contain 100,000 cells. Only recently have sufficient clues become available to suggest how coordinated cell actions might result in slug movement. We propose a “squeeze‐pull” model that involves circumferential cells squeezing forward a cellular core, followed by pulling up of the rear. This model takes into account the different classes of cells in the slug; it is proposed that prestalk cells are engines and prespore cells are the cargo.
Interstrand duplexes in nuclear RNA
Authors: Pogo A. Oscar , Miller Kenton S. 
Published: February 2005

AbstractNuclear intermolecular duplexes appear to be a general feature of nucleated cells. Most of these duplexes are formed between large RNA as well as between large and small RNA molecules. A significant portion of the large molecules belong to a special class of RNA that is restricted to the nucleus and, therefore, not designated for export. These molecules are assembled with proteins and form a structure of a higher order. The possibility that these molecules and a set of small nuclear RNAs are components of a complex machine, “the transportosome”, which functions in nucleocytoplasmic traffic, is discussed.
Testicular leydig cells: Differentiated cells responding to multiple hormonal control and producing varied products
Authors: Melner Michael H. 
Published: February 2005

AbstractLeydig cells, traditionally known as the steroidogenic workhorses of the testis, are now known to synthesize significant amounts of non‐steroid products including some potent bioactive proteins and peptides. These products are currently being investigated for their potential role in the paracrine regulation of spermatogenesis in the nearby seminiferous tubules and in the autocrine regulation of Leydig cell function.
Low energy pulsing electromagnetic fields modify biomedical processes
Authors: Bassett C. A. L. 
Published: February 2005

AbstractLow‐energy, pulsed electromagnetic fields (PEMFs) have reversed therapeutically resistant pathologic processes in the musculo‐skeletal system. Their development as a non‐thermal therapeutic agent is based on 30 years of study of the electro‐biological properties of connective tissues. Specific energy characteristics in applied PEMFs produce selected biological effects by modifying synthetic and other behavioral patterns of target cells; some mechanisms of action are defined. The technology appears safe and effective in clinical treatment of un‐united fractures, avascular necrosis of bone, and chronic, refractory tendinitis. An expanding, rational use in biomedical science is predicted.
Tryptophan synthetase: Its charmed history
Authors: Yanofsky Charles 
Published: February 2005

AbstractTryptophan synthetase was initially selected as a subject for investigation of the relationship between gene structure and protein structure. Early studies with this enzyme first demonstrated the existence in mutants of immunologically cross‐reacting material (CRM) and the restoration of a wild‐type enzyme by genetic suppression. Fine structure analyses with E. coli tryptophan synthetase missense mutants proved the colinearity of gene structure and catalytic capabilities of this enzyme have been subjects for numerous studies.
Bone development and repair
Authors: Caplan Arnold I. 
Published: February 2005

AbstractAlthough bone development during embryogenesis and bone repair after injury have a number of features which appear similar, they are distinctly different processes which involve separate controlling elements and cuing parameters. Repair of bone is influenced by bioactive factors which reside in bone itself; some of these factors are not present when embryonic mesenchymal cells first differentiate. For example, a bone protein which induces the conversion of mesenchymal cells into cartilage cells is not present in the embryo at the site where cartilage first differentiates into the anlagen for future bone. Ultimately, the sequence of cellular and molecular events which controls the success of bone repair is dependent on the prior embryologic and developmental packaging of bioactive factors into bone and the release of these factors at a bone break site. The success of the reparative events depends not only upon the release of these bone‐derived factors but also on systemic factors and the identity and numbers of responding cells at the repair site.
The control of transcription in Saccharomyces cerevisiae
Authors: Stanway Clive , Kingsman Alan J. , Kingsman Susan M. 
Published: February 2005

AbstractThe control of mRNA synthesis in the unicellular eukaryote Saccharomyces cerevisiae involves a number of promoter elements, including an upstream activation site (UAS), an RNA initiation element (RIE) and, for some genes, a form of negative element. The UAS is involved in the activation and regulation of transcription, whilst the RIE, which comprises a transcription initiation site (or I site), and often a TATA box, is responsible for the accurate positioning of the 5′ end of the mRNA. The mechanism whereby these promoter elements interact involves specific protein‐DNA binding events and possibly alterations in chromatin structure.
A potential Z‐DNA‐forming sequence is an essential upstream element of a plant promoter
Authors: An Gynheung 
Published: February 2005

AbstractThe fine‐structure analyses of the nopaline synthase (nos) promoter which is active constitutively in a wide range of plant tissues reveal that a portion of the upstream essential region for maximal transcription is a potential Z‐DNA‐forming element. Z‐DNA sequences are found in almost all plant‐promoter regions, suggesting that these structural elements may play important roles in plant gene expression.
Kinetic isotope effects and ‘metabolic switching’ in cytochrome P450‐catalyzed reactions
Authors: Miwa Gerald T. , Lu Anthony Y. H. 
Published: February 2005

AbstractThe mechanistic significance of a kinetic isotope effect on a cytochrome P‐450catalyzed reaction depends, fundamentally, on the nature of the interaction of the substrate with the active site of the enzyme as well as on the nature of the chemistry of the reaction catalyzed. Consequently, kinetic isotope effects can be used to extract information on the topology of the enzyme and the mechanism of substrate oxidation. Kinetic isotope effect studies are sometimes accompanied by ‘metabolic switching’ or a change in metabolic pathway, catalyzed either by the same enzyme or by a different enzyme. For the specific case where ‘metabolic switching’ gives rise to a change in regional specificity for the cytochrome P‐450 catalyzed metabolism of a compound, this change can be explained in terms of the topological constraints on substrate binding imposed by the active site of the enzyme.
Disulphide bonds and protein stability
Authors: Creighton Thomas E. 
Published: February 2005

AbstractThe properties of disulphide bonds relevant to their roles in stabilizing protein conformation are reviewed. Natural disulphides can stabilize folded conformations substantially, in some cases to much greater extents than would be expected from just entropic effects on the unfolded state. The linkage relationship between conformational stability and disulphide stability is illustrated. Disulphides will not, however, increase protein stability if the disulphides are not maintained in the unfolded state or if instability is caused by processes, such as chemical modification or proteolysis, that are not linked to unfolding, either local or global. This is part of the reason why some recent attempts to increase protein stability by introducing new disulphides have had only modest success. Other reasons appear to be the severe energetic constraints on disulphide bond geometry and, in some cases, unfavourable effects of introducing Cys residues by mutation.
Analysis, design and modification of loop regions in proteins
Authors: Thornton J. M. , Sibanda B. L. , Edwards M. S. , Barlow D. J. 
Published: February 2005

AbstractLoop regions in proteins have traditionally been described as ‘random coil’, although they are known to adopt well‐defined conformations in most globular proteins. In this contribution we summarize the results of detailed analysis of the structures and sequences of these loop regions in proteins of known three‐dimensional structure. We also describe how these results can be used as an aid to protein design, modification and modelling.
Engineering of antibodies
Authors: Verhoeyen Martine , Riechmann Lutz 
Published: February 2005

AbstractHuman monoclonal antibodies are extremely difficult to obtain by hybridoma technology. As an alternative, ‘human‐like’ antibodies have been produced by recombinant DNA technology. The first such engineered antibodies consisted of chimaeric proteins, in which murine variable regions were linked to human constant regions. More recently ‘human’ antibodies have been ‘reshaped’ by transplanting the binding site of a murine antibody into a human antibody. Further‐more antibodies have been dissected into groups of domains (Fab's, Fc's) and for example, Fab's have been joined to enzymes resulting in antibody‐enzyme chimaeras. In addition to their potential clinical applications, engineered antibodies will prove invaluable in studies of structure/function relationships of variable and constant regions.
Hormonal and heat‐stress regulation of protein synthesis in the aleurone layers of barley seeds
Authors: Brown Peter H. , Brodl Mark R. 
Published: February 2005

AbstractBarley aleurone cells have long served as a model system for studying the regulation of gene expression in plants. In this review we survey what is known about hormone‐regulated gene expression in aleurone cells. We also describe the effects of heat stress on gene expression in this system, and speculate how the aleurone cell prioritizes its response between hormone‐induced and environment‐induced programs of gene expression.
The banting and best department of medical research at the university of toronto
Authors: Fritz Irving B. 
Published: February 2005

AbstractPlaces is a Features column presenting descriptions of and reports on major research institutes in biology. Previous articles have dealt with, amongst other institutions, the Imperial Cancer Research Fund, the Marine Biological Laboratory at Woods Hole, the John Innes Institute, and the Department of Embryology of the Carnegie Institute. In the following article, Irving B. Fritz reviews the history and present program of one of Canada's outstanding institutions, the Banting and Best Department of Medical Research of the University of Toronto.
Structure of human serum cholinesterase
Authors: Lockridge Oksana 
Published: February 2005

AbstractHuman cholinesterase has recently been sequenced and cloned. It is a glycoprotein of 4 identical subunits, each subunit containing 9 carbohydrate chains and 3.5 disulfide bonds. Protein folding is likely to be very similar in human cholinesterase and Torpedo acetylcholinesterase. The cholinesterases have no significant sequence homology with the serine proteases and seem to belong to a separate serine esterase family.
Chromatin organization at meiosis
Authors: Møens Peter B. , Pearlman Ronald E. 
Published: February 2005

AbstractFrom 1956, when the complex ultrastructure of meiotic chromosomes was discovered, 1 until 1985, when the isolation of meiotic chromosome cores was reported, knowledge of the molecular structure of the meiotic chromosome was at best a dream. The dissection of meiotic chromosome structures has become a realistic challenge through the arrival of isolated symptonemal complexes (SCs), monoclonal and polyclonal antibodies against SCs, the possibility for screening expression libraries for genes that encode SC proteins, the isolation of SC‐associated DNA, and the development of techniques for the in situ recognition of DNA sequences in the context of the meiotic chromosome structure.
Modulation of myosin assembly
Authors: Epstein Henry F. 
Published: February 2005

AbstractMyosin self‐assembly is generally considered to be the major process in thick filament formation within striated muscles. The biological assembly of myosin into thick filaments is being analysed by genetic dissection as well as biochemical and morphological experiments in the nematode Caenorhabditis elegans. This work shows that the assembly of myosin is modulated by its biosynthesis and interaction with non‐myosin proteins. Assemblages which generate multiple nascent thick filaments may play a central role in a catalytic cycle of myosin assembly.
Mechanism of Mu DNA transposition
Authors: Chaconas George , Surette Michael G. 
Published: February 2005

AbstractThe study of Mu DNA transposition in vitro has resulted in a much better understanding of the biochemical details of the transposition process. An early step in transposition is the generation of a 5th structure which is the product of the strand‐tansfer reaction. The polarity of the strand transfer has been determined and substantial progress has been made on the role of the individual proteins. Moreover, the strand‐transfer reaction is mediated by stable protein–DNA complexes, or transposomes, and the reaction can be divided into two sequential steps. The role of the transposomes and the requirement for a supercoiled Mu DNA substrate are also discussed.
Amphibian metamorphosis: An immunologic opportunity!
Authors: Ruben Laurens N. , Clothier Richard H. , Balls Michael , Horton John D. 
Published: February 2005

AbstractAnuran amphibian metamorphosis is an immunologically interesting period. For the investigator, it provides an unusual opportunity for analyzing both humoral regulation of the immune response and the development and maintenance of self‐tolerance. Some of the questions one can ask are: Why don't immunocompetent larvae destroy antigenically disparate adult cells as they differentiate within them during metamorphosis? Do the dramatic hormonal changes occurring during this period regulate immunological function? How do animals in metamophorsis protect themselves from their immunologically hostile environment?
Cytoplasmic determination and distribution of developmental potential in the embryo of Caenorhabditis elegans
Authors: Schierenberg Einhard 
Published: February 2005

AbstractDevelopment of the nematode Caenorhabditis elegans has been described completely on a cell‐by‐cell basis. In an invariant pattern five somatic founder cells and the primordial germ cell are generated within the first hour after the onset of cleavage. Using a laser microbeam for manipulation of individual blastomers several aspects of early embryogenesis have been investigated, including the expression of cellular polarity, the localization of lineage‐specific cleavage potential, the necessity for early cell–cell interaction, and the control of differential cell‐cycle timing. The experiments demonstrate the central importance of a correct partitioning of cytoplasmic components during early embryogenesis and suggest a stepwise, binary segregation mechanism associated with the unequal cleavages in the germline.
Regulation of the Ca2+ pump atpase by cAMP‐dependent phosphorylation of phospholamban
Authors: Tada Michihiko , Kadoma Masaaki 
Published: February 2005

AbstractCa2+ transients in myocardial cells are modulated by cyclic AMP‐dependent phosphorylation of a protein in the sarcoplasmic reticulum. This protein, termed phospholamban, serves to regulate the Ca2+ pump ATPase of this membrane, thus altering the mode of Ca2+ transients and the myocardial contractile response. Elucidating the structure of phospholamban and its intimate interaction with the Ca2+ pump ATPase should provide the basis for understanding, at the molecular level, how the cAMP system contributes to excitation‐contraction coupling in muscle cells.
Bacterial cell walls and membranes. Discovery of the teichoic acids
Authors: Baddiley James 
Published: February 2005

AbstractTeichoic acids are major wall components of most Gram‐positive bacteria. Their discovery followed that of their nucleotide precursors. Lipoteichoic acids associated with the cell membrane were discovered at the same time. Events leading to these discoveries and the probable function of teichoic acids in cation control are described.
Estrogens, antiestrogens and cell proliferation
Authors: Kon Oi Lian 
Published: February 2005

AbstractThe classical estrogen receptor model does not sufficiently account for the tumor‐promoting activity of extrogens or for the antiproliferative effect of antiestrogens in estrogen‐dependent tumors. Particular difficulties not readily accommodated within the model are that hormonal autonomy can supervene without loss of the estrogen receptor and that antiestrogen effects are highly context‐dependent, without apparent differences in the estrogen receptor itself or in metabolic transformation of antiestrogens. Recent studies suggest that estrogens may promote cell proliferation, in part, through the mediation of growth factors and that antiestrogens may exert some of their effects by mechanisms unrelated to the estrogen receptor.
Essential roles of 70kDa heat inducible proteins
Authors: Craig Elizabeth A. 
Published: February 2005

AbstractThe 70kDa heat inducible proteins (hsp70s) are a highly conserved family of proteins found in every organism examined. Some hsp70 proteins are essential for cell viability. Recent work has revealed that these proteins are involved in the movement of proteins into and through various compartments of the eukaryotic cell.
The discovery of gene amplification in mammalian cells: To be in the right place at the right time
Authors: Schimke Robert T. 
Published: February 2005

AbstractThe constancy of the genome structure of an organism has been accepted dogma for a number of decades. The genetic variegation of maize as described by McClintock in the 1940s and subsequently shown to be mediated by transposable elements indicated a degree of genomic fluidity not appreciated previously. The discovery of gene amplification in somatic mammalian cells in 1977 has added a new component to the phenomenon of genomic fluidity, which has implications for various subdisciplines of biology.
Uvomorulin‐catenin complex: Cytoplasmic anchorage of a Ca2+‐dependent cell adhesion molecule
Authors: Kemler Rolf , Ozawa Masayuki 
Published: February 2005

AbstractThe cytoplasmic domain of the cell adhesion molecule uvomorulin associates with three independent proteins, named catenins, which are structurally related in different cell types of various species. This complex formation connects uvnomorulin and cytoskeletal structures and might, moreover, be involved in other adhesion‐dependent mechanisms.
Genetics of increased lifespan in drosophila
Authors: Rose Michael R. 
Published: February 2005

AbstractNatural selection in the laboratory has been used to produce populations of Drosophila with genetically increased lifespan. These populations have been used to determine the physiological basis of postponed ageing and its pleiotropic concomitants. It appears that many loci and a number of physiological alterations are involved in increased lifespan.
Epithelial shape change in mouse embryonic submandibular gland: Modulation by extracellular matrix components
Authors: Nakanishi Yasuo , Ishii Takahiro 
Published: February 2005

AbstractEarly morphogenesis of mouse submandibular gland provides an excellent model for the formation of epithelial lobules as a consequence of epithelial‐mesenchymal interactions. Both proteoglycans and a glycosaminoglycan, high molecular weight components which contain amino‐sugars and hexuronic acids, seem to be important in maintaining the lobular structure through the formation of epithelial basal lamina. Collagen also appears to play a crucial role in this morphogenesis. By visualizing the distribution of collagen fibrils and by changing the concentration of collagen in the gland, we have developed a new hypothesis which emphasizes the mechanical role of mesenchyme in epithelial cleft formation. Precise mechanisms for the involvement of these molecules have not been elucidated, yet it is now clear that knowledge of the function of the extracellular matrix components is a prerequisite for understanding the epithelial‐mesenchymal interactions.