bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of the cell nucleus
Authors: Cavalier‐Smith T. 
Published: February 2005

AbstractThe origin of mitosis and the nuclear envelope were the pivotal processes in the evolutionary origin of the nucleus; they probably occurred in a wall‐less mutant bacterium that evolved a cytoskeleton and phagocytosis about 1500 million years ago. Principles of intracellular coevolution clarify their origin, as well as that of nucleosomes, spliceosomes, and the evolution of genome size.
Novel cell surface receptors during mammalian fertilization and development
Authors: Hathaway Helen J. , Shur Barry D. 
Published: February 2005

AbstractEmbryogenesis requires the precise movement and reorganization of many cell and tissue types. Presumably, cell surface receptors allow cells to interact selectively with adjacent cells and with the extracellular environment, as well as initiate differentiative events by transducing appropriate signals across the plasma membrane. One cell surface component that serves as a receptor during a variety of cellular interactions is β1,4‐galactosyltransferase. Cell surface galactosyltransferase participates in diverse cellular interactions by binding its specific glycoconjugate substrate on adjacent cell surfaces or in the extracellular matrix. Biochemical, immunological, and molecular probes are being used to better define cell surface galactosyl‐transferase functional in cellular interactions during fertilization, intercellular adhesion, cell migration, and growth control.
Human papillomaviruses in oncogenesis
Authors: Lazo Pedro A. 
Published: February 2005

AbstractPapillomaviruses, long associated with benign skin tumors, have been linked more recently to human cancers, particularly to cervical carcinoma. Molecular analysis of the virus has identified the transforming gene and its regulation by both viral and cellular trans:‐acting factors. This viral regulatory mechanism is altered in carcinomas. However, lack of progress in developing an in vitro system has hampered investigation of the viral life cycle and the biology of the virus‐‐host: cell interaction.
Genetic control of vaccine‐induced immunity against a parasitic helminth, Schistosoma mansoni
Authors: Sher Alan , James Stephanie 
Published: February 2005

AbstractSchistosoma mansoni is one of several species of trematode helminths responsible for schistosomiasis, a major parasitic infection of man. Genetic analysis in mice has revealed that the protective immunity induced against this parasite by an attenuated larval vaccine is strongly influenced by genes regulating the activation of macrophage effector cells. The latter finding suggests that the induction of cell‐mediated immunity may be a successful strategy for a non‐living vaccine against the human infection.
The search for morphogenes in Dictyostelium
Authors: Bloom Laird , Kay Robert R. 
Published: February 2005

AbstractClassical embryological studies have led to the suggestion that cells in developing tissues may be directed to differentiate along a particular pathway by the concentrations of molecules called morphogens. Studies of the slime mould Dictyostelium discoideum, which has a simple tissue pattern consisting of only two cell types, have revealed several molecules which may act as morphogens. Cyclic AMP and ammonia promote the formation of spores, while adenosine and a novel class of compounds called DIFs promote the formation of stalk cells, the alternative cell fate. The constant proportions of the two differentiated cell types observed in this organism may result from a balance among the influences of these compounds.
Genetic polymorphism and cancer susceptibility: Evidence concerning acetyltransferases and cancer of the urinary bladder
Authors: Hein David W. 
Published: February 2005

AbstractAcetyltransferase enzymes expressed in hepatic and extrahepatic tissues are products of an acetyltransferase gene locus. Acetylation capacity is regulated by simple autosomal Mendelian inheritance of two codominant alleles at this locus. Human slow acetylators are predisposed to bladder cancer from arylamine chemicals. The role of the bladder in arylamine metabolism and of bladder acetyltransferases in the etiology of bladder cancer is not fully understood, but the acetylator genotype‐dependent expression of arylamine N‐acetyltransferase and N‐hydroxyarylamine O‐acetyltransferase in bladder cytosol may contribute towards the genetic predisposition of human slow acetylators to arylamine‐induced bladder cancer.
Structural characteristics of two highly selective opioid peptides
Authors: Knapp Richard J. , Yamamura Henry I. , Kazmierski Wieslaw , Hruby Victor J. 
Published: February 2005

AbstractThe demonstration of opioid receptors by radioligand binding and the discovery of their endogenous peptide ligands has provided a new class of compounds that can be used for the development of novel opioids. The number of potential receptor targets for such opioids has been expanded by the identification of multiple opioid receptor types The development of highly selective opioid peptides using the principles of conformational restriction permits the analysis of the structure‐activity requirements of each receptor type, and is facilitating the elucidation of the functional properties of the different opioid receptors.
Cellular and molecular biology of alzheimer's disease
Authors: Price Donald L. , Koo Edward H. , Unterbeck Axel 
Published: February 2005

AbstractAlzheimer's disease results from the degeneration of neurons. Degenerating nerve cells express atypical proteins, and amyloid is deposited. We suggest that some of these events are strongly influenced by genetic factors and age. Animal models should be useful in investigating the pathogenic mechanisms that lead to the brain abnormalities seen in this disease.
Plant viruses: A tool‐box for genetic engineering and crop protection
Authors: Michael T. , Wilson A. 
Published: February 2005

AbstractTraditionally, plant viruses are viewed as harmful, undesirable pathogens. However, their genomes can provide several useful ‘designer functions’ or ‘sequence modules’ with which to tailor future gene vectors for plant or general biotechnology.The majority (77 %) of known plant viruses have single‐stranded RNA of the messenger (protein coding) sense as their genetic material. Over the past 4 years, improved in vitro transcription systems and the construction of partial of fulllength DNA copies of several plant RNA viruses have enhanced our ability to manipulate and study their genomes, particularly in the context of their pathogenic interactions with host plants.Recently, two forms of genetically engineered protection against plant virus infections have been reported. In both, a virus‐related ‘interfering’ molecule was stably introduced into plants via the DNA‐transfer mechanism of Agro‐bacterium tumefaciens. To date, the choice of ‘interfering’ molecule has been guided by empirical field‐observations and each is effective against only a narrow range of closely‐related viruses. As yet, we do not fully understand the molecular mechanism(s) responsible for the observed protection.The ability to manipulate the plant–pathogen relationship is a powerful tool to increase our knowledge and improve future strategies for uncoventional cropprotection by genetic engineering techniques.
Regulation of mast cell differentiation
Authors: Kitamura Yukihiko , Fujita Jun 
Published: February 2005

AbstractMast cells are a unique class of blood cell. Unlike most blood cells, undifferentiated precursors of mast cells migrate in the bloodstream, invade tissues, proliferate there and then differentiate. Even after differentiation, some mast cells may proliferate extensively. Differentiation of mast cells is regulated by both diffusible growth factors and direct contact with fibroblasts.
Position effect variegation in Drosophila: Towards a genetics of chromatin assembly
Authors: Eissenberg Joel C. 
Published: February 2005

AbstractThe formation of a highly condensed chromosome structure (heterochromatin) in a region of a eukaryotic chromosome can inactivate the genes within that region. Genetic studies using the fruitfly Drosophila melanogaster have identified several essential genes which influence the formation of heterochromatin. My purpose in this review is to summarize some recent work on the genetics of heterochromatin assembly in Drosophila and a recent model for how chromosomal proteins may interact to form a heterochromatic structure.
RNA folding: Pseudoknots, loops and bulges
Authors: Wyatt Jacqueline R. , Puglisi Joseph D. , Tinoco Ignacio 
Published: February 2005

AbstractThe three‐dimensional structures adopted by RNA molecules are crucial to their biological functions. The nucleotides of an RNA molecule interact to form characteristic secondary‐structure mctifs. Tertiary interactions orient these secondary‐structure elements with respect to each other to form the functional RNA. Here we describe the basic structural elements with special emphasis on a novel tertiary motif, the pseudoknot.
Poliovirus translation: A paradigm for a novel initiation mechanism
Authors: Sonenberg Nahum , Pelletier Jerry 
Published: February 2005

AbstractAll eukaryotic cellular mRNAs, and most viral mRNAs, are blocked at their 5′ ends with a cap structure (m7GpppX, where × is any nucleotide). Poliovirus, along with a small number of other animal and plant viral mRNAs, does not contain a 5′ cap structure. Since the cap structure functions to facilitate ribosome binding to mRNA, translation of poliovirus must proceed by a cap‐independent mechanism. Consistent with this, recent studies have shown that ribosomes can bind to an internal region within the long 5′ noncoding sequence of poliovirus RNA. Possible mechanisms for cap‐independent translation are discussed. Cap‐independent translation of poliovirus RNA is of major importance to the mechanism of shut‐off of host protein synthesis after infection. Moreover, it is likely to play a role in determining poliovirus neurovirulence and attenuation.
A spontaneous sarcoma dependent on host tumor‐specific immune lymphocytes
Authors: Katz Jonathan D. , Bonavida Benjamin 
Published: February 2005

AbstractThe immune surveillance theory postulates that spontaneous tumors are normally rejected by the immune system and appear only when they override host‐immune recognition and rejection mechanisms. The present mini‐review describes a spontaneous tumor system, the reticulum cell sarcomas (RCS) in SJL/J mice, that is dependent on host tumor‐specific immune lymphocytes for growth. This continuous tumor‐specific response results in tumor progression and death of the host. This tumor system contradicts the basic concept of immune surveillance. We propose as an explanation that some highly antigenic tumors, like the RCS, may have evolved in a non‐autonomous fashion but, nevertheless, have lost regulatory controls of cell proliferation. In the RCS system, the tumor expresses Class II MHC I‐E like specificities that are not expressed on the host cells and which selectively stimulate a subpopulation of I‐E specific T cells, the Vβ17a+ clonotype, leading to their expansion and continuous nurturing of the tumor via secreted lymphokines. This neoantigenic stimulation bypasses the tumor regulatory response that might have resulted if the tumor had not expressed neo‐antigens. Furthermore, passive administration of anti‐clonotypic antibody to tumor‐bearing mice results in tumor regression and long‐term survival through removal of the tumor reactive T cells. Thus, in this tumor system, immunosuppressive treatments are the prescription for tumor rejection.
Functional and dynamic aspects of the mammalian nucleolus
Authors: Scheer Ulrich , Benavente Ricardo 
Published: February 2005

AbstractNucleoli are the sites of ribosome biogenesis. Transcription of the ribosomal RNA genes as well as processing and initial packaging of their transcripts with ribosomal and non‐ribosomal proteins all occur within the nucleolus in an ordered manner and under defined topological conditions. Components of the nucleolus have been localized by immunocytochemistry and their functional aspects investigated by microinjection of antibodies directed against the enzyme responsible for rDNA transcription, RNA polymerase I. The role of nascent transcripts in postmitotic formation of nucleoli will be discussed.
Calmodulin‐dependent protein kinase II
Authors: Fujisawa Hitoshi 
Published: February 2005

AbstractThree multifunctional protein kinases, cyclic AMP‐dependent protein kinase, protein kinase C, and calmodulin‐dependent protein kinase II, are involved in signal transduction in response to their respective second messengers, cyclic AMP, diacylglycerol, and Ca2+. This review will summarize the key findings on calmodulin‐dependent protein kinase II.
The regulation of DNA repair during development
Authors: Mitchell David L. , Hartman Philip S. 
Published: February 2005

AbstractDNA repair is important in such phenomena as carcinogenesis and aging. While much is known about DNA repair in single‐cell systems such as bacteria, yeast, and cultured mammalian cells, it is necessary to examine DNA repair in a developmental context in order to completely understand its processes in complex metazoa such as man. We present data to support the notion that proliferating cells from organ systems, tumors, and embryos have a greater DNA repair capacity than terminally differentiated, nonproliferating cells. Differential expression of repair genes and accessibility of chromatin to repair enzymes are considered as determinants in the developmental regulation of DNA repair.
Processing of recombination intermediates in vitro
Authors: West Stephen C. 
Published: February 2005

AbstractGenetic recombination involves the exchange of genetic material between chromosomes to produce new assortments of alleles. As such, it affects one of the most fundamental and important components of heredity – the genome itself. To understand the molecular basis of recombination, efforts have been directed to try to determine how simple organisms recombine their DNA. One approach involves the development of in vitro systems in which recombination reactions can be studied using purified enzymes. Detailed studies of these systems, using enzymes isolated from bacteria and bacterial viruses, indicate the formation of unique protein‐DNA complexes. The structure of the DNA within these complexes has important consequences for the subsequent formation of recombinant products.
Dissecting the complexity of the nervous system by enhancer detection
Authors: Bellen Hugo J. , Wilson Clive , Gehring Walter J. 
Published: February 2005

AbstractEnhancer detectors are DNA constructs which, when introduced into a eukaryotic genome, respond to nearby genomic transcriptional regulatory elements by means of a reporter gene, revealing the expression pattern of genes in their vicinity. Recent experiments in Drosophila suggest that enhancer detection is a powerful method to identify genes that are expressed in the nervous system. Since enhancer detectors allow a rapid molecular and genetic characterization of genes in their vicinity, the method will greatly facilitate the study of neural development and behavior.
Telomeres, telomerase and senescence
Authors: Greider Carol W. 
Published: February 2005

AbstractEukaryotic chromosomes end with tandem repeats of simple sequences. These GC rich repeats allow telomere replication and stabilize chromosome ends. Telomere replication involves an equilibrium of sequence loss and addition at the ends of chromosomes. Repeats are added de novo by telomerase, an unusual DNA polymerase. Telomerase is an RNP in which an essential RNA component provides the template for the added telomere repeats. Telomere length maintenance plays an essential role in cell viability.
Multiple mechanisms in the regulation of ethanol‐inducible cytochrome P450IIE1
Authors: Koop Dennis R. , Tierney Daniel J. 
Published: February 2005

AbstractCytochrome P450IIE1 is involved in the metabolic activation of many xenobiotics involved with human toxicity. In particular, cellular concentrations of P450IIE1 are significantly induced by the most widely abused drug in our society today, alcohol. As a result, the synthesis and degradation of this form of P450 has significant health consequences. The regulation of the steady‐state concentration of P450IIE1 is an extremely complex process. The enzyme is regulated by transcriptional activation, mRNA stabilization, increased mRNA translatability and decreased protein degradation. The principal mechanism which controls the induction process depends on the chemical nature of the inducer, the age, and the nutritional and hormonal status of the animal. There also appear to be significant sex differences in the expression of P450IIE1. It is entirely possible that the regulation of the enzyme concentration under any given set of conditions will involve all of the mechanisms to different extents.
Mismatch repair in mammalian cells
Authors: Heywood Louise A. , Burke Julian F. 
Published: February 2005

AbstractA vital process in maintaining a low genetic error rate is the removal of mismatched bases in DNA. The importance of this process in E. coli is demonstrated by the 100–1000 fold increase in mutation frequency observed in cells deficient in this repair system(1). Mismatches can arise as a consequence of recombination, errors in replication and as a result of spontaneous chemical deamination, the latter process resulting in an estimated twelve T:G mismatches per genome per day in mammalian cells(2). Recent studies, discussed here, provide evidence for the existence of specific mismatch repair systems in mammalian and human cells.
Defining components required for transport from the ER to the golgi complex in yeast
Authors: Newman Anna P. , Ferro‐Novick Susan 
Published: February 2005

AbstractSeveral complementary approaches have been fruitful in the study of transport from the ER to the Golgi complex in yeast. Mutational analysis has led to the identification of genes required for this process, many of which are now being studied at the molecular and biochemical level. In the case of SEC18, DNA sequence analysis has demonstrated homology to a factor needed for transport in mammalian in vitro systems. In addition, the events that take place at this stage of the secretory pathway have been reconstituted in vitro.
Problems And Paradigms: Ionising radiations from nuclear establishments and childhood leukaemias – an enigma
Authors: Evans H. J. 
Published: February 2005

AbstractThe Gardner report, recently published in the UK, showing a correlation between incidence of childhood leukaemia and paternal exposure to ionising radiations (amongst fathers working in nuclear power plants) has added a new element to debates about both the risk factors in nuclear power plants and the relationships between ionising radiations and leukaemogenesis. The epidemiologic and genetic evidence concerning leukaemias is reviewed here and it is concluded that the leukaemogenic agent, whose existence is indicated in the Gardner report, is unlikely to be paternal radiation dose per se but rather exposure to another factor that is correlated with paternal radiation dose received.
Regional neural induction in Xenopus laevis
Authors: Sharpe Colin R. 
Published: February 2005

AbstractDuring development of the Xenopus embryo, the formation of the nervous system depends on an inductive interaction between mesoderm and ectoderm. The result is a neural tube that is regionally differentiated along the anterior–posterior axis from forebrain to spinal cord (Fig. 1). The discovery of genes whose transcripts can be used as molecular markers for different regions of the nervous system has permitted reassessment of the existing theories of neural tissue formation. Although the neural inducing molecules remain elusive, the mechanism by which cells interact to form a regionally differentiated nervous system is becoming clearer.
Roots: Selective reminiscences of β‐lactam antibiotics: Early research on penicillin and cephalosporins
Authors: Abraham Edward 
Published: February 2005

AbstractThe discovery, made in Oxford, that crude penicillin could cure systemic and life‐threatening bacterial infections was followed by attempts to purify penicillin, to determine its structure and then to produce it by total chemical synthesis. The β‐lactam structure of the molecule, first proposed in October 1943, was a source of controversy until 1945. However, no useful chemical synthesis was achieved and fermentation became the commercial source of the antibiotic.In 1953, one of the products of a Cephalosporium sp. from Sardinia was shown to be a new and hydrophilic penicillin (penicillin N). This was contaminated with a substance having the same side‐chain but a characteristic absorption spectrum. The latter, cephalosporin C, showed antibacterial activity but was not inactivated by a penicillinase. The determination of its β‐lactam structure and isolation of its nucleus enabled pharmaceutical companies to produce many semisynthetic cephalosporins.A new tripeptide was later found to be an intermediate in the biosynthesis of both penicillin N and cephalosporin C, and this was followed by the complete elucidation of the biosynthetic pathways leading to these compounds and to benzylpenicillin.
Steroid hormone receptors and In vitro transcription
Authors: Allan George F. , Tsai Sophia Y. , O'Malley Bert W. , Tsai Ming‐Jer 
Published: February 2005

AbstractSteroid hormone receptors are ligand‐inducible transcription factors that exhibit potent effects on gene expression in living cells. Precise dissection of their mode of action at the molecular level can best be carried out in functional cell‐free systems. This article will describe the benefits of such systems and review their development up to the recent establishment of steroid receptor‐dependent in vitro transcription. Subsequent advances in our knowledge of receptor function arising from the exploitation of this powerful experimental tool will be described. Particular emphasis will be placed upon two key problems: the role of steroid hormone in receptor action and the mechanisms by which steroid receptors activate gene transcription.
Structure and evolution of the actin crosslinking proteins
Authors: Dubreuil Ronald R. 
Published: February 2005

AbstractThe actin crosslinking proteins exhibit marked diversity in size and shape and crosslink actin filaments in different ways. Amino acid sequence analysis of many of these proteins has provided clues to the origin of their diversity. Spectrin, α‐actinin, ABP‐120, ABP‐280, fimbrin, and dystrophin share a homologous sequence segment that is implicated as the common actin binding domain. The remainder of each protein consists of repetitive and non‐repetitive sequence segments that have been shuffled and multiplied in evolution to produce a variety of proteins that are related in function and in composition, but that differ significantly in structure.