bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic metalloporphyrins: A class of compounds of pharmacological interest
Authors: Kappas Attallah , Drummond George S. 
Published: February 2005

AbstractStudies of the regulation of heme oxygenase by synthetic metalloporphyrins reveal that within this group of compounds there exist both inducers and inhibitors of the synthesis of this enzyme or of its catalytic function. The ability of metalloporphyrins to alter heme catabolism is of considerable experimental and clinical interest since such alterations may have consequences for other aspects of heme homeostasis, including its synthesis and its function in the form of cytochrome(s) P‐450. Examples of the metabolic effects – and their potential clinical and pharmacological consequences – produced by two synthetic metalloporphyrins, Sn‐protoporphyrin and Co‐protoporphyrin, are discussed.
Transcriptional regulation of mammalian ribosomal RNA genes
Authors: Muramatsu Masami 
Published: February 2005

AbstractEukaryotic genes are divided into three categories according to the machineries by which they are transcribed. Ribosomal RNA genes (rDNA) are the only ones that are transcribed by RNA polymerase I and are under different control from other genes transcribed by RNA polymerase II or III. None the less, the regulation of rDNA is of prime interest in view of its close relationship to cell growth and differentiation. In this review I shall discuss the recent progress in the study of transcription mechanisms of rDNA by the RNA polymerase I system. The structure of the rDNA promoter and the presence of possible upstream enhancer regions will be described. In addition, factors involved in the transcription initiation of this gene will be discussed with special reference to the formation of an initiation complex.
What the papers say: Molecular karyotypes: Separating chromosomes on gels
Authors: Corcoran Lynn M. 
Published: February 2005

AbstractFor many years, there has been a gap in our capacity to study the structure and organization of chromosomal DNA molecules. The very small genomes of some viruses and bacteriophages (≤ 50,000 bp or 50 kb) are amenable to analysis by conventional gel electrophoresis, while the extremely large DNA molecules (> 100,000 kb) comprising the chromosomes of higher eukaryotes have been analysed under the light microscope, using a range of banding and in situ hybridization techniques. However, intact DNA molecules with sizes between these two extremes have been largely inaccessible experimentally. This gap has recently been bridged with the development of two‐dimensional electrophoretic procedures that allow the separation and purification of chromosome‐sized DNA molecules ranging from ∼ 50 kb to several thousand kb.1–3 There are currently two variations of the technique in use: pulsed field gradient (PFG) gel electrophoresis1,2 and orthogonal‐field‐alteration gel electrophoresis (OFAGE).3 Both are based on a common principle, differing primarily in the geometry of the electrodes. Already, they have been employed to determine the approximate chromosome sizes and numbers for a variety of lower eukaryotes, including yeast and several protozoa.2–10 These ‘molecular karyotypes’ provide fundamental information about the genomic organization of each organism, and allow very rapid construction of linkage maps. Surprisingly, they have also revealed a remarkable plasticity in the genomes of several lower eukaryotes.
Transcriptional regulatory sequences from plant viruses
Authors: Kridl Jean C. , Goodman Robert M. 
Published: February 2005

AbstractTwo groups of plant viruses have DNA in their genomes. One group, the caulimoviruses, are non‐integrating retroviruses that package dsDNA in virions. The other group, the geminiviruses, package small circular ssDNA and include the only DNA viruses known with bipartite genomes. The regulation of transcription of these viruses is not well characterized, but recent work is beginning to yield interesting results. Regulatory sequences from these viruses function in cells of species that are not hosts of the virus and are finding use in constitutive expression of chimeric genes in transformed plants. Development of vectors based on plant viruses requires further characterization at the molecular level of viral life cycles.
The role of cAMP in controlling yeast cell division
Authors: Ishikawa Tatsuo , Uno Isao , Matsumoto Kunihiro 
Published: February 2005

AbstractThe studies on the cAMP‐requiring mutants and their suppressors in the yeast, Saccharomyces cerevisiae, revealed that cAMP‐dependent protein phosphorylation is involved in the G1 phase of the cell cycle, in conjugation, and in the post‐meiotic stage of sporulation, and that inhibition of cAMP‐dependent protein phosphorylation is required to induce meiotic division.
Coordinated assembly of the developing Egg
Authors: Tata Jamshed R. 
Published: February 2005

AbstractThe developing vertebrate oocyte autonomously makes most of the components of the machinery for DNA and protein synthesis, as well as ‘maternal’ mRNAs, needed immediately after fertilization. However, specialized egg constituents such as yolk proteins, egg white, cholesterol, lipoproteins and egg coat substances, are formed in the liver, oviduct and perhaps in follicle cells. The assembly of the developing egg is therefore a fascinating example of division of labor among oocytes and extra‐oocyte tissues, the coordination of activities of the latter being achieved by hormones.
Genetic basis for familial amyloidotic polyneuropathy
Authors: Shimada Kazunori , Maeda Shuichiro , Araki Shukuro 
Published: February 2005

AbstractFamilial amyloidotic polyneuropathy (FAP) is an inherited systemic amyloidosis, characterized by the extracellular deposition of fibrillar amyloid protein, i.e. a variant type of prealbumin, and by prominent peripheral nerve involvement. We recently established the basis of FAP, using a cloned human prealbumin cDNA, restriction endonuclease(s) and Southern blot procedures. This approach clearly revealed a direct link between mutation in the prealbumin gene and FAP; individuals with FAP are heterozygous for the prealbumin gene, carrying one normal and one mutant gene. Molecular analysis of the prealbumin gene yielded pertinent data on the genetic basis for FAP.
A novel coenzymatic function of pyridoxal 5′‐phosphate
Authors: Fukui Toshio , Tagaya Mitsuo 
Published: February 2005

AbstractPyridoxal 5′‐phosphate, the vitamin B6 derivative, acts as the coenzyme of many enzymes involved in amino acid metabolism. Exceptionally, this compound was found covalently bound to glycogen phosphorylase, the key enzyme in the regulation of glycogen metabolism. Although it is essential for the function of phosphorylase, its direct role has remained an enigma. We have recently found that the glucose moiety of pyridoxal (5′)diphospho (1)‐α‐D‐glucose, a conjugate of pyridoxal 5′‐phosphate and glucose 1‐phosphate through a pyrophosphate linkage, is transferred to the nonreducing end of glycogen, forming a new α‐1,4‐glucosidic linkage. This finding emphasizes the importance of the direct phosphate‐phosphate interaction between the coenzyme and the substrate in the phosphorylase catalytic reaction. We have proposed a catalytic mechanism for phosphorylase in which the phosphate group of pyridoxal 5′‐phosphate acts as an electrophile to the phosphate group of glucose 1‐phosphate. This appears to represent the first instance of the direct involvement of a phosphate group in catalysis by enzymes.
Retroviral elements and suppressor genes in Drosophila
Authors: Parkhurst Susan M. , Corces Victor G. 
Published: February 2005

AbstractThe phenotype of some spontaneous mutations in Drosophila can be modified by mutations at unlinked loci. The affected alleles are caused by the insertion of retroviral transposable elements. The idiosyncratic functional and structural properties of these elements play a key role in determining the expression characteristics of the genes into which they are inserted. These phenotypes are reversed or intensified by the allelic state of suppressor and enhancer loci through changes in the transcriptional properties of the transposable elements.
Membrane contacts and lens transparency
Authors: Kistler Joerg , Bullivant Stanley 
Published: February 2005

AbstractTwo kinds of membrane contacts in the vertebrate lens are described. Fiber gap junctions are domains where small molecules can pass between lens cells. Membrane structures of ball‐and‐socket type interlock adjacent lens fibers and thus contribute to the structural integrity of the lens. Both of these membrane contacts appear crucial for the maintenance of lens transparency.
Slime moulds and the origin of foldback DNA
Authors: Hardman Norman 
Published: February 2005

AbstractThe genomes of the slime moulds are relatively small when compared with those of higher eukaryotes. They also contain far fewer families of repetitive sequences. Nevertheless, the general patterns of organization of their repetitive DNA are similar. The slime moulds can therefore help us to investigate the structure and evolution of repetitive DNA in “simple” eukaryotes and to understand how these sequences contribute to the architecture and function of the eukaryotic genome. Several questions remain, including perhaps the most important: do repetitive sequences perform some definable function?.
Rules of retinotectal mapmaking
Authors: Easter Stephen S. 
Published: February 2005

AbstractThe selective connections that nerve cells make to each other and to effector and receptor cells outside the nervous system are essential to organized behavior. The retinotectal projection has been used frequently in the experimental investigation of how such patterned sets of connections are formed. This article traces the evolution of some of the dominant experimental paradigms and concepts that have resulted in the currently accepted rules underlying the retinotectal map.
The use of vaccinia virus for the construction of recombinant vaccines
Authors: Piccini Antonia , Paoletti Enzo 
Published: February 2005

AbstractRecombinant DNA technology has been used to engineer vaccinia virus genetically into a eukaryotic expression vector. An exciting outcome of these gene‐splicing techniques is that after the insertion of one or more genes which encode the information for antigens responsible for conferring immunity toward an infectious disease, vaccinia can be adapted for the development of live recombinant vaccines. This review discusses recombinant vaccinia design and the feasibility of using these vaccines for disease protection.
Virus, toxin, complement: Common actions and their prevention by Ca2+ Or Zn2+
Authors: Pasternak Charles A. 
Published: February 2005

AbstractMembrane damage induced by haemolytic agents does not necessarily lead to lysis: the pores that are formed at low concentration of agent are formed at low concentration of agent are not large enough to allow leakage of cytoplasmic proteins, and in many instances the lesions become repaired with time. Quite different agents induce a similar type of lesion: in each case leakage is reduced at low ionic strenth, and is prevented by divalent cations such as Ca2+ or Zn2+, suggesting a possible therapeutic approach to the containment of several membrane‐damaging diseases.
Regulation of expression of the c‐Myc proto‐oncogene
Authors: Marcu Kenneth B. 
Published: February 2005

AbstractThe c‐myc proto‐oncogene is normally subject to complex regulation at the transcriptional and post‐transcriptional levels in proliferating and differentiating cells. It is activated in response to growth stimuli and generally, though not always, repressed in response to differentiation signals. Abnormal, deregulated c‐myc expression is a common feature of numerous malignancies and occurs by a variety of molecular mechanisms which probably reflect the existence of multiple factors responsible for its normal control. Here, I provide a detailed summary of recent progress and current views on c‐myc gene regulation.
Molecular genetic aspects of sex determination in Drosophila
Authors: Baker Bruce S. , Nagoshi Rodney N. , Burtis Kenneth C. 
Published: February 2005

AbstractAnalysis of the mechanisms underlying sex determination and sex differentiation in Drosophila has provided evidence for a complex but comprehensible regulatory hierarchy governing these developmental decisions. It is suggested here that the pattern of sexual differentiation and dosage compensation characteristic of the male is a default regulatory state. Recent results have provided, in addition, some surprising and intriguing conclusions: (1) that several of the critical controlling genes produce more transcripts than was predicted from the genetic analyses; (2) that setting of the alternative sex‐specific states of the doublesex (dsx) locus involves differential transcript processing; and (3) that some aspects of sexual differentation require the prolonged action of certain elements of the regulatory hierarchy. These findings are discussed in connection with the current model of sex determination in Drosophila.
DNA repair in man: Regulation by a multigene family and association with human disease
Authors: Cleaver James E. , Karentz Deneb 
Published: February 2005

AbstractThe major mechanism of repair of damage to DNA involves a conceptually simple process of enzymatic excision and resynthesis of small regions of DNA. In man and other mammals, this process is regulated by several gene loci; up to 15 mutually complementary genes or gene products may be involved. Repair deficiency results in an array of clinical symptoms in skin, central nervous system, and hematopoietic and immune systems, the major example being xeroderma pigmentosum (XP), a disease with a high incidence of cancer. Cloning repair genes by straightforward methods has proved difficult, but we have begun the effort by demonstrating that correction of a human repair deficiency can be achieved by transferring very small fragments of DNA from normal hamsters into XP cells. One of the complementation groups of XP cells (group C) appears to express a change in gene regulation such that these cells repair only a small clustered region of the DNA with high efficiency.
Nonneural microtubule proteins: Structure and function
Authors: Macrae Thomas H. 
Published: February 2005

AbstractAnalysis of microtubule proteins from several sources has revealed a molecular complexity consistent with the proposed multi‐functional nature of tubulin and microtubule‐associated proteins (MAP). Less certain is the actual range of functions attributable to microtubules and how the variability exhibited by the microtubule proteins translates into functional specificity. In spite of the conceptual difficulties, an exciting picture of structure/function integration is emerging from the study of microtubules.
Dengue haemorrhagic fever: Virus or host response?
Authors: Pang Tikki 
Published: February 2005

AbstractThe pathogenesis of dengue haemorrhagic fever has been the subject of intense research and considerable controversy. One hypothesis proposes that the immune response in a sensitized host is the primary mechanism. In contrast, others have suggested that the disease is caused by a more virulent, variant strain of dengue virus. Recent advances in molecular biology and hybridoma technology are providing valuable clues toward a solution and illustrating the fact that the course of a human viral disease is often a net result of unseparated interactions between host and virus.
Structure and function of chimaeric antibodies
Authors: Ahmed Nizamuddin 
Published: February 2005

AbstractRecent techniques allow the introduction of in vitro‐manipulated immunoglobulin genes into myeloma cells to produce chimaeric antibodies. These antibodies contain the antigen‐binding variable region (V) of one species linked either to the heavy chain constant region (C) of another species or to a completely unrelated protein, such as that of certain enzymes. Apart from having novel functions and diagnostic and therapeutic applications, these antibody‐related molecules are also valuable in immunochemical studies.
Regulation of mitochondrial gene expression in Trypanosoma brucei
Authors: Stuart Kenneth D. 
Published: February 2005

AbstractTrypanosoma brucei mitochondria contain unusual small circular DNAs of unknown function. These are catenated with a long informational DNA sequence containing genes homologous to those found in other mitochondria. Although these genes are transcribed throughout the life cycle, differential production of the mitochondrial respiratory system during the life cycle is accompanied by differential abundance of specific transcripts and differential polyadenylation of mitochondrial gene transcripts. Multiple transcripts occur for most of the mitochondrial genes. Transcripts of the apocytochrome b gene possessing nucleotide sequences at their 5′ ends which are not present in mitochondrial DNA are found at stages of the life cycle when the respiratory system is expressed. These results suggest the presence of post‐transcriptional mechanisms that regulate the expression of mitochondrial genes during the life cycle of T. brucei.
Antifertility factors of mammalian seminal fluid
Authors: Shivaji S. , Bhargava P. M. 
Published: February 2005

AbstractThe fertilizing ability of spermatozoa is inhibited by certain substances present in the seminal fluid. Most of these antifertility factors are proteinaceous in nature and differ in their physical characteristics. They inhibit fertilization by inhibiting either motility, capacitation, acrosome reaction or penetration of the ovum investments by the spermatozoa. This review describes and discusses the properties of these factors and their possible role, individually and collectively, in the regulation of fertility.
Towards a molecular understanding of differentiation mechanisms in ascidian embryos
Authors: Satoh Noriyuki 
Published: February 2005

AbstractThe ascidian embryo has long provided a model system for ‘mosaic’ development. This article reviews recent advances in the study of ascidian developmental biology. These include: (a) the re‐analysis of cell lineages in ascidian embryos with the ascertainment of developmental fates of every blastomere of a 110‐cell embryo; (b) the development of several tissue‐specific monoclonal antibodies; (c) the investigation and description of cell cycle requirements for differentiation; it has been found that neither cytokinesis nor nuclear division is required for differentiation, but that several rounds of DNA replication are essential for the expression of certain tissue‐specific genes; and (d) the demonstration by new descriptive and experimental studies of the presence of cytoplasmic factors or determinants responsible for specification of embryonic cell features; myoplasm which is thought to contain muscle determinants has been isolated, and immunological attempts to elucidate the molecular nature of the factors have begun.
Molecular analysis of Duchenne and Becker muscular dystrophy
Authors: Worton Ronald G. 
Published: February 2005

AbstractDuchenne muscular dystrophy (DMD) is a progressive and lethal neuromuscular disorder caused by a defective gene on the X chromosome. There is no effective treatment and the biochemical defect is yet unknown. Mapping of the DMD locus to band Xp21 in the short arm of the X chromosome has given rise to strategies to clone the gene from its known location in the chromosome. Two cloning strategies have led to the isolation of a gene that is the largest of any yet described. Portions of the gene are deleted in about 8% of affected males, and rare translocations that disrupt the gene cause the disease in females. The isolation of expressed sequences from the DMD locus will undoubtedly lead to isolation of the gene product and ultimately to an understanding of the basic defect. In the meantime, DNA probes from the DMD locus provide a new and accurate approach for carrier identification and prenatal diagnosis of this dreaded disease.
The evolution of RNA viruses
Authors: Rossmann Michael G. 
Published: February 2005

AbstractThe structures of spherical RNA plant tiruses, containing 180 copies of one protein subunit, are closely related to those of the animal RNA picornaviruses, which are built of 60 copies of each of three larger capsid proteins. Other spherical RNA and DNA viruses utilize the same structural motif as building units of the viral capsid. It is therefore probable that many of the simple RNA viruses, whether found in animals or plants, have had a common genetic origin. The original gene may have coded for a protein that bound to specific molecules on the cell surface.
Desmutagens and bio‐antimutagens – their modes of action
Authors: Kada Tsuneo , Shimoi Kayoko 
Published: February 2005

AbstractThere are two ways of preventing induced cellular mutagenesis. In the first, mutagens are inactivated by ‘desmutagens’ before they can attack the DNA. In the second, ‘bio‐antimutagens’ interfere with cellular fixation processes working on damage in DNA. Examples of modes of action are shown for these inhibitors of induced mutations and implications for reducing genetic damage in man are discussed.
Metabolic mayhem caused by 2‐ketoacid imbalances
Authors: LaRossa Robert A. , Van Dyk Tina K. 
Published: February 2005

AbstractA variety of herbicides act by inhibiting the branched chain amino‐acid biosynthetic enzyme, acetolactate synthase (EC 4.1.3.18). The initial consequences of this event are 2‐ketoacid accumulation and amino‐acid starvation. Recent studies demonstrate that 2‐ketoacid imbalances play a significant role in the action of these herbicides; such imbalances may also be important in certain inborn errors of human metabolism.
Regulation of non‐muscle myosin structure and function
Authors: Citi Sandra , Kendrick‐Jones John 
Published: February 2005

AbstractIn vertebrate and invertebrate nonmuscle myosins, light‐ and heavy‐chain phosphorylation regulate myosin assembly into filaments, and interaction with actin. Vertebrate non‐muscle myosins can exist in vitro in three main states, either ‘folded’ (assembly‐blocked) or ‘extended’ (assembly‐competent) monomers, and filaments. Light‐chain phosphorylation regulates the ‘dynamic equilibrium’ between these states. The ability of the myosin to undergo changes in conformation and state of assembly may be an important mechanism in regulating the organization of the cytoskeleton and cell motility.
Nuclear lamin proteins and the structure of the nuclear envelope: Where is the function?
Authors: McKeon Frank D. 
Published: February 2005

AbstractThe nuclear envelope has recently become the object of intense scrutiny because it is the site of nuclear transport and is possibly involved in the organization of the interphase genome, thereby affecting gene expression. The major structural support for the nuclear envelope is the nuclear lamina, composed of the nuclear lamin proteins. They lie on the surface of the inner nuclear membrane and are in direct contact with the chromatin at the edge of the nucleus. The structure of the nuclear lamin proteins has recently been deduced from their cDNAs and shown to have remarkable homologies to the family of cytoplasmic intermediate filaments. However, the lamin proteins have been found to depolymerize in response to metaphase‐specific phosphorylation events, and reassemble around daughter chromosomes at the completion of cell division. Little is known of the mechanisms of these dynamics, nor of other post‐translational modifications evident in these proteins. In addition, we have as yet no concrete idea of the function of these highly conserved proteins in the cell. This review will summarize our present knowledge of nuclear lamin structure and the new experimental approaches designed to elucidate their function.