bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unusual features of cereal seed protein structure and evolution
Authors: Kreis Martin , Shewry Peter R. 
Published: February 2005

AbstractThe alcohol‐soluble (prolamin) storage proteins of barley, wheat and rye vary in their structures, but all have two features in common: the presence of distinct structural domains differing in amino acid compositions, and of repeats within one of these domains. Detailed comparisons of amino acid sequences show that all appear to have evolved from a single ancestral gene consisting of three short related regions (called A, B and C). Regions related to A, B and C are also present in the minor prolamins of maize and in three other groups of seed proteins: inhibitors of α‐amylase and /or trypsin from cereals. 2S storage globulins from several dicotyledonous species and a 2S albumin from sunflower. It is suggested that these proteins together constitute a protein superfamily with limited sequence homology.
Inherited sensitivity to X‐rays in man
Authors: Thacker John 
Published: February 2005

AbstractAtaxia‐telangiectasia (A‐T), an inherited disorder giving radiation sensitivity and cancer‐proneness, is discussed in terms of a defect in ability to repair DNA damage. A new assay using damaged recombinant DNA molecules suggests that the fidelity of repair of DNA double‐strand breaks is reduced in an A‐T cell line. Specific chromosomal changes in some A‐T patients appear to be associated with cancer induction, and it is suggested that these could be linked to a DNA repair‐fidelity defect. However, a general correlation between radiosensitivity and cancer‐proneness is difficult to establish at present, partly because of diversity in radiosensitivity in the normal population.
Invertebrate cytokines: The phylogenetic emergence of interleukin‐1
Authors: Beck Gregory , O'Brien Robert F. , Habicht Gail S. 
Published: February 2005

AbstractCytokines are polypeptides released by activated vertebrate blood cells which have profound effects on other blood cells and which have hormone‐like properties affecting other organ systems as well. In recent years a wide variety of these mediators has been isolated and characterized. Many of these molecules have subsequently been cloned and expressed in E. coli. The tremendous importance of these proteins to host immune and non‐specific defense systems along with the striking similarities of their properties among different species suggested to us that cytokines may have been proteins that have been conserved through evolution. Investigations of the evolution of cytokines will help us decipher the complex cellular, humoral and molecular interactions that regulate host defenses. Studies of the invertebrates will shed light on the phylogenetic emergence of these molecules as well.
Generation of multiple N‐CAM polypeptides from a single gene
Authors: Walsh Frank S. , Dickson George 
Published: February 2005

AbstractThe neural cell adhesion molecule (N‐CAM) is believed to be a key regulator of adhesive events in the nervous system and skeletal muscle. The recent isolation of N‐CAM cDNAs from different tissues has identified a high degree of diversity in primary amino acid sequence between different isoforms. In this article, we review these recent studies and discuss methods for unravelling the functional consequences of the generation of multiple N‐CAM polypeptides using gene transfection approaches.
The biosynthetic potential of plant roots
Authors: Signs Mark W. , Flores Hector E. 
Published: February 2005

AbstractThe contribution of roots to the biology of the whole plant is being reevaluated in the light of classical and recent findings. In addition to their role in water and nutrient uptake and in symbiotic associations, plant roots also synthesize a remarkable variety of secondary metabolites. These chemicals, many of which are used as pharmaceuticals, agrichemicals, flavors, dyes, or fragrances, may help the plant cope with biotic and abiotic stress. Root cultures are being used as experimental systems to explore both root‐specific secondary metabolites and their biological significance. They may also provide future systems for commercial production of plant specialty chemicals.
Phylogenetic distribution and function of arylalkylamine N‐acetyltransferase
Authors: Smith Timothy J. 
Published: February 2005

AbstractAmine acetylation is a diverse topic with importance to the regulation of several physiological processes as well as the metabolism of drugs and environmental chemicals. Arylalkylamine N‐acetyltransferase is widely distributed in several species, where this enzyme plays an important role in the seasonal regulation of reproduction and photoperiodism in vertebrates through the pathway of melatonin formation. In insects, this enzyme is involved in monoamine neurotransmitter inactivation and the formation of catecholamine intermediates necessary for sclerotization of the insect cuticle.
Regulation of cell‐type‐specific transcription and differentiation of the pituitary
Authors: Sharp Z. Dave , Cao Zhaodan 
Published: February 2005

AbstractThe transcription of rat prolactin and growth hormone genes in vitro requires a pituitary transcription factor, specific to certain cell types in the pituitary, which currently appears to be the PUF‐I/Pit‐1/GHF‐1 protein. This factor binds to cis‐regulatory elements in the 5′ region of both genes and exerts a positive influence on transcription initiation presumably by interacting with general transcription factors. The PUF‐I/Pit‐1/GHF‐1 transcriptional regulatory protein probably has an important role in not only the differentiation of the pituitary lactotroph/somatotroph cell lineage; it is also expressed in the early development of the nervous system but its function there is less well documented. It appears to be one member of a family of trans‐activator proteins involved in differential gene expression in several cell types.
Transcriptional regulation of the Drosophila segmentation gene fushi tarazu (ftz)
Authors: Dearolf Charles R. , Topol Joanne , Parker Carl S. 
Published: February 2005

Abstractftz is one of the ‘pair rule’ segmentation genes of Drosophila melanogaster, and is an important component of the segmentation process in the fruit fly. We discuss the transcriptional mechanism which causes ftz to be expressed in a seven stripe pattern during embryogenesis.
Determination of cell fate in sea urchin embryos
Authors: Livingston Brian T. , Wilt Fred H. 
Published: February 2005

AbstractClassical embryological studies have provided a great deal of information on the autonomy and stability of cell fate determination in early sea urchin embryos. However, these studies were limited by the tools available at the time, and the interpretation of the results of these experiments was limited by the lack of information available at the molecular level. Recent studies which have re‐examined classical experiments at the molecular level have provided important new insights into the mechanism of determination in sea urchins, and require us to re‐evaluate some long standing theories on the process of differentiation.
Environmental stimuli and transcriptional activity generate transient changes in DNA torsional tension
Authors: Saavedra Raul A. 
Published: February 2005

AbstractTransient changes in DNA torsional tension are generated by environmental stimuli and transcriptional activity. In eukaryotic cells, these changes can only be accommodated by a chromatin structure that is flexible. This property of chromatin may be essential to the regulation of eukaryotic gene activity.
My favourite molecule: Discovery of the nucleolar targeting signal
Authors: Hatanaka Masakazu 
Published: February 2005

AbstractThe discovery of the signal peptides that direct proteins to localize at the nucleolus is described here. The nucleolar targeting signal termed the NOS consists of clustered basic amino acids organized such that a portion also functions as the nuclear transporting signal. Although a NOS has been identified within the regulatory genes of human retroviruses, HTLV‐I and HIV‐I, signals of similar function in cellular proteins – such as heat shock proteins – may be induced through the configurational change of protein structure by heat or stress.
The synapsins and the regulation of synaptic function
Authors: Bähler Martin , Benfenati Fabio , Valtorta Flavia , Greengard Paul 
Published: February 2005

AbstractSynapsins I and II are a family of synaptic vesicle‐associated phosphoproteins involved in the short‐term regulation of neurotransmitter release. In this review, we discuss a working model for the molecular mechanisms by which the synapsins act. We propose that synapsin I links synaptic vesicles to actin filaments in the presynaptic nerve terminal and that these interactions are modulated by the reversible phosphorylation of synapsin I through various signal transduction pathways. The high degree of homology between the synapsins suggests that some of the functional properties of synapsin I are also shared by synapsin II.
Genetic control of cell communication in C. elegans development
Authors: Maine Eleanor M. , Kimble Judith 
Published: February 2005

AbstractCell communication is crucial for many aspects of growth and differentiation during the development of the nematode Caenorhabditis elegans. Two genes, glp‐1 and lin‐12, mediate a number of known cell–cell interactions. Genetic and molecular analyses of these two genes lead to the conclusion that they are structurally and functionally related. We summarize these studies as well as those involving the identification of other genes that interact with glp‐1 and / or lin‐12.
Inherited disorders of vitamin B12 utilization
Authors: Rosenblatt David S. , Cooper Bernard A. 
Published: February 2005

AbstractInborn errors of vitamin B12 (cobalamin) metabolism are associated with homocystinuria and methylmalonic aciduria, either alone or in combination. A number of these disorders have provided the first evidence for the existence of important steps in the transport or metabolism of cobalamin in eukaryotic cells. Eight complementation classes have been defined on the basis of somatic cell hybridization studies. Although the majority of patients present in infancy or early childhood, some are not diagnosed until adolescence or later. For some of these disorders, prenatal diagnosis and therapy with cobalamin during pregnancy has been attempted. Although only males have been described with cblE disease, all of these disorders are presumed to be autosomal recessive in inheritance. The clinical and laboratory aspects of the different complementation classes (cblA–cblG) are reviewed here.
Cell‐cell adhesion molecules in Dictyostelium
Authors: Siu Chi‐Hung 
Published: February 2005

AbstractMulticellularity in the cellular slime mold Dictyostelium discoideum is achieved by the expression of two types of cell–cell adhesion sites. The EDTA‐sensitive adhesion sites are expressed very early in the developmental cycle and a surface glycoprotein of 24000 Da is known to be responsible for these sites. The EDTA‐resistant contact sites begin to accumulate on the cell surface at the aggregation stage of development. Several glycoproteins have been implicated in the EDTA‐resistant type of cell–cell binding and the best characterized one has an Mr of 80000 (gp80). gp80 mediates cell–cell binding via homophilic interaction and its cell binding site has been mapped to an octapeptide sequence. The mechanism by which gp80 mediates cell–cell adhesion will be discussed.
Problems And Paradigms: Metaphors and the role of genes in development
Authors: Nijhout H. F. 
Published: February 2005

AbstractIn describing the flawless regularity of developmental processes and the correlation between changes at certain genetic loci and changes in morphology, biologists frequently employ two metaphors: that genes ‘control’ development, and that genomes embody ‘programs’ for development. Although these metaphors have an admirable sharpness and punch, they lead, when taken literally, to highly distorted pictures of developmental processes. A more balanced, and useful, view of the role of genes in development is that they act as suppliers of the material needs of development and, in some instances, as context‐dependent catalysts of cellular changes, rather than as ‘controllers’ of developmental progress and direction. The consequences of adopting this alternative view of development are discussed.
Puffs and gene regulation — molecular insights into the Drosophila ecdysone regulatory hierarchy
Authors: Thummel Carl S. 
Published: February 2005

AbstractSixteen years ago, Michael Ashburner and his colleagues proposed a hierarchical model for the genetic control of polytene chromosome puffing by the steroid hormone ecdysone. The recent molecular isolation and characterization of three early ecdysone‐inducible genes has confirmed many aspects of this model — these genes are directly induced by ecdysone, repressed by ecdysone‐induced proteins, and appear to encode DNA binding regulatory proteins. The three early genes are also remarkably similar in structure. They are all unusually long and complex, with multiple transcripts that direct the synthesis of several related proteins from each locus. Proteins encoded by two of the early genes bind to both early and late ecdysone‐induced puffs, implying that they are key regulators in the hierarchy.
Neural repair and glial proliferation: Parallels with gliogenesis in insects
Authors: Smith Peter J. S. , Shepherd David , Edwards John S. 
Published: February 2005

AbstractThere is a growing recognition, stemming from work with both vertebrates and invertebrates, that the capacity for neuronal regeneration is critically dependent on the local microenvironment. That environment is largely created by the non‐neuronal elements of the nervous system, the neuroglia. Therefore an understanding of how glial cells respond to injury is crucial to understanding neuronal regeneration. Here we examine the process of repair in a relatively simple nervous system, that of the insect, in which it is possible to define precisely the cellular events of the repair process. This repair is rapid and well organised; it involves the recruitment of blood cells, the division of endogenous glial elements and, possibly, migration from pre‐existing glial pools in adjacent ganglia. There are clear parallels between the events of repair and those of normal glial development. It seems likely that the ability of the insect central nervous system to repair resides in the retention of developmental capacities throughout its life and that damage results in the activation of this potential.
The ‘A rule’ of mutagen specificity: A consequence of DNA polymerase bypass of non‐instructional lesions?
Authors: Strauss Bernard S. 
Published: February 2005

AbstractThe replicative bypass of lesions in DNA and the induction of mutations by agents which react with DNA to produce damaged bases can be understood on the basis of a simple kinetic model. Bypass can be analyzed by separately considering three processes: (a) addition of a base opposite a lesion, (b) a proofreading excision process, and (c) a rate limiting elongation step. Adenine nucleotides are preferentially added opposite many lesions making it possible to predict mutational specificity. Replicative bypass (translesion synthesis) is dependent on modulation of proofreading exonuclease activity but loss of exonuclease activity alone is not sufficient to ensure bypass. Frameshift mutation is the result of the failure of translesion synthesis accompanied by rearrangement of the template, particularly at repetitive sites.
High frequency force generation in outer hair cells from the mammalian ear
Authors: Holley Matthew 
Published: February 2005

AbstractMammalian outer hair cells generate mechanical forces at acoustic frequencies and can thus amplify the sound stimulus within the inner ear. The mechanism of force generation depends upon the plasma membrane potential but not upon either calcium or ATP. Forces are generated in the lateral cortex along the full length of the cell. The cortex includes a two‐dimensional cytoskeletal lattice composed of circumferential filaments 6–7 nm thick that are cross‐linked by filaments 3–4 nm thick and 40–60 nm long. The two filament types may, respectively, be actin and some form of spectrin. The lattice reinforces the cylindrical shape of the cell and permits limited changes in length. Beneath it lie the lateral cisternae, a regular system of multi‐layered membranes. Force–generation may depend upon voltage‐dependent shape changes in proteins that lie either in the plasma membrane or in the cytoskeletal lattice.
Actin filaments and photoreceptor membrane turnover
Authors: Williams David S. 
Published: February 2005

AbstractThe shape and turnover of photoreceptor membranes appears to depend on associated actin filaments. In dipterans, the photoreceptor membrane is microvillar. It is turned over by the addition of new membrane at the bases of the microvilli and by subsequent shedding, mostly from the distal ends. Each microvillus contains actin filaments as a component of its cytoskeletal core. Two myosin I‐like proteins co‐localize with the actin filaments. It is suggested that one of the myosin I‐like proteins might be linked to the microvillar membrane. By interacting with the actin filaments, this motor should move the membrane of a microvillus in a distal direction, thus providing a possible mechanism for the turnover of the membrane.A vertebrate photoreceptor cell contains a small cluster of actin filaments in its connecting cilium at the site where new transductive disk membranes are formed. Disruption of the actin filaments perturbs disk morphogenesis. The most likely explanation for this perturbation is that the process of initiating a new disk is inhibited. Conventional myosin (myosin II) is found in the connecting cilium with the same distribution as actin. A simple model is proposed to illustrate how the actin–myosin system of the connecting cilium might function to initiate the morphogenesis of a disk membrane.
Exons – original building blocks of proteins?
Authors: Patthy László 
Published: February 2005

AbstractIn a recent paper, Walter Gilbert's group has estimated the number of original exons from which all extant proteins might have been constructed. The approach used is subjected to a critical analysis here. It is shown that there are flawed assumptions about both the mechanism and generality of exon‐shuffling and in the sequence comparison procedures employed, the latter failing to distinguish chance similarity from similarity due to common ancestry. These methodological errors lead to the omission of many known cases of exonshuffling and the inclusion of others which may not be genuine. In consequence, the analysis from the Gilbert group cannot give a reliable estimate of those modules that actually participated in exon‐shuffling and provides no information on the number of protein archetypes that did not participate in these processes.
Actin in the Drosophila embryo: Is there a relationship to developmental cue localization?
Authors: Bearer Elaine L. 
Published: February 2005

AbstractRecent genetic manipulations have revealed that the cytoplasm of the early Drosophila embryo contains localized information that specifies the future embryonic axes. It is the restricted distribution or activity of particular gene products, either messenger RNA or protein, that is crucial for this specification. While some of the genes responsible for this information have been seqenced and the nature and distribution of their products examined, it is not known how this localization is established or maintained. The actin‐based cytoskeleton is a likely candidate for the formation of a cytomatrix that would allow such distributions and yet no direct evidence has yet been found that implicates actin in positional cue localization. In this review I summarize what is known about actin filament behavior. in Drosophila embryos and compare it to the distribution of positional cues. My purpose is to juxtapose these two bodies of information such that the relationship between them may be revealed.
Eukaryotic DNA repair: Glimpses through the yeast Saccharomyces cerevisiae
Authors: Friedberg Errol C. 
Published: February 2005

AbstractEukaryotic cells are able to mount several genetically complex cellular responses to DNA damage. The yeast Saccharomyces cerevisiae is a genetically well characterized organism that is also amenable to molecular and biochemical studies. Hence, this organism has provided a useful and informative model for dissecting the biochemistry and molecular biology of DNA repair in eukaryotes.
Gene expression, cellular diversification and tumor progression to the metastatic phenotype
Authors: Nicolson Garth L. 
Published: February 2005

AbstractAlterations in the expression of certain genes or in their products can render benign tumor cells metastatic. Experimentally this has been quickly performed by transferring dominantly acting oncogenes such as c‐H‐rasEJ into susceptible cells, but in vivo such a rapid qualitative change in a dominantly acting oncogene occurs only rarely, and progression to highly metastatic phenotypes is thought to occur through a slow stepwise process. Such slow changes can be reversible and need not involve known dominantly acting oncogenes, consistent with clinical observations. An important element of the natural progression of tumors to malignancy may be their ability to circumvent microenvironmental controls that regulate growth and cellular diversity and to evolve into heterogeneous phenotypes, a process that appears to involve mainly quantitative changes in gene expression but which can be rapidly stimulated in cell culture by the introduction of a dominantly acting oncogene. It is proposed that the highly malignant cells that have slowly evolved in vivo with only a few qualitative gene changes have undergone extensive cycles of diversification and accumulation of quantitative changes in the expression of genes that encode products that are related to malignancy and metastasis. Thus, highly malignant cellular phenotypes can arise quickly through specific qualitative changes in critical controlling genes or more slowly by less critical qualitative genetic changes, coupled with cellular diversification and accumulation of quantitative changes in gene expression.
Expression patterns of mouse hox genes: Clues to an understanding of developmental and evolutionary strategies
Authors: Gaunt Stephen J. 
Published: February 2005

AbstractExpression patterns of Antennapedia‐like homeogenes in the mouse embryo show many similarities to those of their homologues in Drosophila. It is argued here that homeogenes may regulate development of the body plan in mouse by mechanisms similar to those used in Drosophila. In particular, they may differentially specify positional address of cell groups within lineage compartments along the body axes. In vertebrates, a single ancestral homeogene cluster has become duplicated to give four separate clusters. Comparisons of homeogene expression patterns between different clusters of the mouse suggest ways in which duplication has permitted development of a more complex body plan. Cluster duplication may therefore have provided a selective advantage during vertebrate evolution.
The biology of cancer metastasis or, ‘you cannot fix it if you do not know how it works’
Authors: Fidler Isaiah J. 
Published: February 2005

AbstractThe major cause of death from cancer is the relentless growth of metastases that are resistant to conventional therapy. The pathogenesis of a metastasis is complex and requires that tumor cells complete a sequence of potentially lethal interactions with various host factors. The finding in 1973 that metastasis is selective process and the finding in 1977 that malignant neoplasms are heterogeneous and contain few preexisting metastatic subpopulations have added a new dimension to our understanding of cancer and its spread. This understanding is now contributing to the design of better therapies against disseminated metastasis.