bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomical characteristics of individual roots within the fine‐root architecture of Chamaecyparis obtusa (Sieb. & Zucc.) in organic and mineral soil layers
Authors: Hishi Takuo , Tateno Ryunosuke , Takeda Hiroshi 
Published: May 2006

AbstractNutrient availability and temporal variation of physical stress are usually higher in organic soil layers than in mineral soils. Individual roots within the fine‐root system adjust anatomical, morphological, and turnover characteristics to soil conditions, for example nutrient availability and physical stresses. We investigated anatomical traits, including cork formation and passage and protoxylem cell numbers, in cross‐sections of individual fine roots of the conifer Chamaecyparis obtusa (Siebold & Zucc.) growing under different soil conditions. The fine‐root systems in different soil layers were compared by sampling ingrowth cores buried for 1 year and filled with organic and mineral soil substrates. The number of exodermal passage cells was lower in roots from organic soils than in those from mineral soils, suggesting that apical roots tend to be more stress‐tolerant in the organic layer than in mineral soils. In contrast, both root tip and specific root tip density were higher in roots from organic soils than in those from mineral soil layers. The proportion of roots with two strands of protoxylem (diarch) was greater in organic (90%) than in mineral (25%) soils. Thus, although the absorptivity of individual apical roots decreases in organic layers, the absorptivity of the entire fine‐root system of C. obtusa may be increased as a result of the increase in apical root density and the proportion of ephemeral roots. We found that the fine‐root system had simultaneous plasticity in density, anatomy, and architecture in response to complex soil conditions.
Factors distinguishing suicide attempters from suicide ideators in a community sample: social issues and physical health problems
Authors: FAIRWEATHER A. K. , ANSTEY K. J. , RODGERS B. , BUTTERWORTH P. 
Published: May 2006

Background. Few studies have focused on factors that uniquely distinguish suicide attempters from suicide ideators. This study assesses prevalence of suicide attempts among suicide ideators within a community sample; explores demographics, employment status, mental and physical health conditions, personality, life stresses and social environment as factors that may distinguish these groups; examines effects of age and gender upon suicide attempts and associated factors; and investigates the increase in suicide attempts when multiple factors related to this behaviour are present.Method. Data were drawn from the PATH Through Life Project, a community survey of 7485 people in Canberra, Australia. A subsample of 522 suicide ideators were used for this study.Results. Logistic regression was used to identify factors associated with suicide attempts. Physical medical conditions (OR 1·95) and negative interactions with friends (OR 1·20) were associated with an increased likelihood of suicide attempts among suicide ideators. Age and gender interaction effects for suicide attempts were found involving physical medical condition and mastery among men (OR 3·78 and 0·83 respectively) and not being employed for those aged 40–44 years (OR 8·94). A cumulative effect was found when multiple factors associated with suicide attempts were present, and the probability of an attempt was significantly elevated.Conclusions. Factors distinguishing those who attempt suicide from suicide ideators involve being unemployed, physical ill health and relationship difficulties. Contrary to expectation, this study found that ideators and attempters experience comparable levels of depression and anxiety.
The temporal relationship of the onsets of alcohol dependence and major depression: using a genetically informative study design
Authors: KUO PO-HSIU , GARDNER CHARLES O. , KENDLER KENNETH S. , PRESCOTT CAROL A. 
Published: May 2006

Background. Although alcohol dependence (AD) and major depression (MD) are highly co-morbid, their causal relationship is unclear. In this longitudinal study, we used a genetically informative population-based twin sample to examine the age-at-onset distributions and the temporal relationship of AD and MD.Method. Our sample included 7477 twins, whose diagnoses of AD and MD and age-at-onset information were obtained from structured interviews. Individual-level survival analyses were conducted based on 2603 monozygotic (MZ) twins, and co-twin diagnosis was included in models as an index of familiar liability to AD and MD.Results. The age-at-onset distributions of AD and MD differed substantially. Most onsets of AD were in young adulthood, whereas MD had a flatter distribution across age. Most subjects, especially women, had an onset of MD preceding AD. Prior MD significantly affected risk for developing AD, and this risk decreased over time. By contrast, preceding AD had negligible effects on the risk for future MD. Familial risk was transmitted within disorders but there was little evidence of additional familial liability shared across disorders.Conclusions. Risk for developing AD was substantially increased by a prior episode of MD. The association was only partially accounted for by familial factors, providing support for a direct causal effect such as self-medication. The etiologic path from AD to MD was insignificant.
ORGAN-SPECIFIC ESTROGEN-INDUCED RNA SYNTHESIS RESOLVED BY DNA-RNA HYBRIDIZATION IN THE DOMESTIC FOWL
Authors: Hahn William E. , Schjeide O. A. , Gorbman Aubrey 
Published: May 2006

In the domestic fowl and other oviparous vertebrates, estrogens induce hepatic synthesis of yolk proteins. The oviduct also increases in size and produces ovalbumin when estrogens are administered. DNA-RNA hybridization assays indicate that within 105 minutes following treatment with estrone the liver of immature pullets contains most, if not all, of the liver RNA species that are present in the livers of the laying hen. Because of limitations of the nucleic acid hybridization technique, which remain to be clearly defined, it is not known whether the hepatic RNA populations in estrone-treated pullets and laying hens are completely homologous or differ in some important way. The results indicate that the genomic response in the avian liver to exogenous estrone is „normal” (relative to the laying hen) and further suggest that the hepatic response to estrogen is primarily pertinent to vitellinogenesis.
DNA-RNA hybridization assays on total RNA also indicate that estrogen-induced RNA species in the liver are not homologous to estrogen-evoked RNA species of the oviduct. Therefore, in these two target organs estrogen-evoked RNA synthesis appears to be in part organ-specific. These data indicate that the specificity of hormone action can be explained in part on the basis of induced synthesis of specific RNA molecules. Whether these alterations in transcription are due to indirect hormonal action or are the result of a primary action of estrogens or estrogen-binding site complexes on the genome and/or its repressors remains a basic question.
THE CONDENSATION OF THE ADENYLATES OF THE AMINO ACIDS COMMON TO PROTEIN
Authors: Krampitz Gottfried , Fox Sidney W. 
Published: May 2006

Simultaneous formation of the adenylates of the 18 amino acids common to protein, followed by cocondensation, has yielded polymers containing all of those amino acids. The condensation occurred rapidly at room temperature above pH 7. The activated amino acids were reacted with thermally synthesized polyanhydro-α-amino acids to yield polymers of substantially increased size. The modified polyamino acids form micron-sized particles which demonstrate internal synthesis by growth and budding. These particles are stable over a wide range of pH.
From thermal polyamino acids alone, answers have earlier been obtained, in principle, to questions of the primordial origin of enzymes, cellular structure, membranes, systematic anhydroamino acid sequences, and propagation of microsystems. Such a model is largely heterotrophic; the mixed adenylate condensation provides, in principle, a partial answer to the origin of syntheses of peptide bonds within protocellular structures.
PHYSIOLOGICAL ROLE OF 70
S
RIBOSOMES IN BACTERIA
Authors: Algranati Israel D. , Gonzalez Nelida S. , Bade Ernesto G. 
Published: May 2006

Evidence is presented indicating that free 70S ribosomes are real components of
Bacillus stearothermophilus
and
Escherichia coli
in exponential and stationary phases of growth.

After pulses of radioactive leucine or uracil were given, protein synthesis was instantaneously stopped by chloramphenicol, or polypeptide growth was allowed to proceed to completion in slowly cooled cells. Analysis of label distribution in sucrose gradients showed that 70S monomers, and not subunits, are final products of translation.
A ribosome cycle for protein synthesis in bacteria is proposed.
THE MECHANISM OF ACTION OF RIBONUCLEASE
Authors: Roberts Gordon C. K. , Dennis Edward A. , Meadows Donella H. , Cohen Jack S. , Jardetzky Oleg 
Published: May 2006

The possible mechanisms of action of bovine pancreatic ribonuclease are discussed in the light of the detailed knowledge of the geometry of the active site that has been derived from studies of inhibitor binding by X-ray diffraction and nuclear magnetic resonance. When combined with a knowledge of the mechanism of phosphate ester hydrolysis, this information imposes severe geometric constraints on possible mechanisms of action of the enzyme. Two types of mechanism can be distinguished, the linear and the pseudorotation. The linear mechanism includes a catalytic role for both histidine residues at the active site and does not involve pseudorotation of the intermediate. In contrast, in the pseudorotation mechanism one histidine residue performs all the catalytic functions, while the other serves only to bind the phosphate anion; this necessarily involves pseudorotation of the intermediate and specific protonation of the leaving group by the enzyme.
The mode of binding of the product of the reaction, cytidine-3′-monophosphate, has been elucidated by X-ray diffraction and nuclear magnetic resonance. If the substrate binds in an analogous way, only the linear mechanism is possible. This mechanism is described in detail.
HEMOGLOBIN A: AN ELECTRON PARAMAGNETIC RESONANCE STUDY OF THE EFFECTS OF INTERCHAIN CONTACTS ON THE HEME SYMMETRY OF HIGH-SPIN AND LOW-SPIN DERIVATIVES OF FERRIC ALPHA CHAINS
Authors: Peisach J. , Blumberg W. E. , Wittenberg B. A. , Wittenberg J. B. , Kampa L. 
Published: May 2006

Hemoglobin, the oxygen-binding heme protein of blood is composed of four subunits of two types, alpha and beta. Although the protein when isolated is diamagnetic, by oxidation it can be converted to various paramagnetic ferric forms exhibiting specific electron paramagnetic resonance (EPR) spectra. Using electron paramagnetic resonance, we have shown that the symmetry of the heme of isolated ferric alpha chains is different from that of the heme of these same subunits when associated with ferric beta chains in the parent tetramer. The high-spin form of the isolated ferric alpha chains shows a clearly resolved departure from tetragonal symmetry in contrast to ferrihemoglobin A, where the environment of the iron of all four chains is nearly tetragonal. This difference in heme symmetry suggests that the maintenance of tetragonal symmetry in the hemoglobin tetramer must be brought about by the configuration the alpha chains assume due to their contact with the beta chains. When isolated from the tetramer, some parts of the alpha chain must undergo physical displacement from a configuration that had been stabilized by the beta chains.
Although differences in symmetry between monomer and tetramer are seen with high-spin forms, no such difference exists with two low-spin ferric forms. Here the symmetries of iron are primarily governed by the immediate ligand environment of the iron and not by the state of association of the protein.
THE STRUCTURE OF CARBOXYPEPTIDASE A, IX. THE X-RAY DIFFRACTION RESULTS IN THE LIGHT OF THE CHEMICAL SEQUENCE
Authors: Lipscomb William N. , Hartsuck Jean A. , Quiocho Florante A. , Reeke George N. 
Published: May 2006

Several features of carboxypeptidase A (CPA) which were previously established by the X-ray diffraction structure studies have now been confirmed by the chemical sequence analysis. These results include the number (307) of amino acid residues in CPA
α
, the identities of the residues (Arg 145, Glu 270, and Tyr 248) shown by the X-ray study to be involved in substrate binding and catalysis, and the existence of a disulfide bond.

The Zn ligands, shown by the X-ray study to be residues 69, 72, and 196 and identified as His, Glx, and either Glx or Lys, are proved by the chemical sequence to be His, Glu, and His, respectively.
No change is required in our previous mechanistic deductions, which are here extended to include a specific mechanism of activation of the substrate by a net charge on the metal ion, which suffers a change in local dielectric constant when it is covered by a substrate.
Comparative Properties of RNA and DNA Templates for the DNA Polymerase of Rous Sarcoma Virus
Authors: Duesberg Peter , Helm Klaus V. D. , Canaani Eli 
Published: May 2006

Several natural RNAs were compared with respect to their template activities for the DNA polymerase of Rous Sarcoma Virus during a 2-hr incubation period. 60-70S viral RNA was found to be a 5- to 10-fold better template than heat-dissociated Rous viral RNA, influenza virus RNA, tobacco mosaic virus RNA, or ribosomal RNA. Denatured salmon DNA is a little better, and poly(dAT) is 2-4 times better as a template for the enzyme than is 60-70S Rous viral RNA. The 60-70S RNAs of different strains of avian tumor viruses have very similar template activities for a given avian tumor virus DNA polymerase. Oligo(dT) or oligo(dC) were found to enhance the template activity of heat-dissociated Rous viral RNA 20- to 30-fold, and that of other natural RNAs tested one- to several-fold. DNA syntheses of 1-24% were obtained during a 2-hour incubation of the enzyme with the above RNA templates. The results suggest that the enzyme prefers partially doublestranded or hybrid regions of RNAs for optimal DNA synthesis, but certain regions of single-stranded RNA can also serve as templates.
Poly(dAT) competes with viral RNA for purified DNA polymerase during DNA synthesis, as would be expected if RNA- and DNA-dependent DNA synthesis was performed by at least one common active site of the same enzyme.
Differential Effect of 5-Bromodeoxyuridine on the Concentrations of Specific Enzymes in Hepatoma Cells in Culture
Authors: Stellwagen Robert H. , Tomkins Gordon M. 
Published: May 2006

Growth of cultured rat hepatoma cells in the presence of 5-bromodeoxyuridine results in a rapid inhibition of the synthesis of adrenal steroid-inducible tyrosine aminotransferase (EC 2.6.1.5) and slower decreases in the concentrations of lactate dehydrogenase (EC 1.1.1.27), alcohol dehydrogenase (EC.1.1.1.1), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49). During the same period, neither overall cell growth nor the concentrations of malate dehydrogenase (EC 1.1.1.37), acid phosphatase (EC 3.1.3.2), or alanine aminotransferase (EC 2.6.1.2) were significantly decreased by the base analog. Addition of thymidine to the growth medium rapidly counteracts the inhibition of tyrosine aminotransferase synthesis but restores the normal concentrations of lactate-, alcohol-, and glucose-6-phosphate dehydrogenases much more slowly. Growth of the cells for only one generation in the presence of bromodeoxyuridine, followed by the addition of thymidine, produces transient decreases in the concentrations of the three “late-responding“ dehydrogenases, beginning 2-3 generations after exposure to the analog.
It is concluded that the selective inhibitory effects of the analog could result from a mechanism in which bromodeoxyuridine is uniformly incorporated into cellular DNA, but inhibits the transcription of only certain genes into messenger RNA. A mathematical model is derived to account for the observed differences in the kinetics of the inhibition of synthesis of the gene products that are sensitive to the analog.
Magnetic Anisotropy and the Orientation of Retinal Rods in a Homogeneous Magnetic Field
Authors: Hong Felix T. , Mauzerall David , Mauro Alexander 
Published: May 2006

The reported orientation of retinal rods in a homogeneous magnetic field can be explained by the magnetic anisotropy of oriented molecules in the disc membranes of the rods.
The energy of a single rod as a function of orientation in the magnetic field, the time required for alingment of the rod in a viscous medium, and the fluctuations of orientation are calculated. Arguments that rhodopsin is the constituent responsible for the effect are given. The possibility of orientation due to inhomogeneity of the magnetic field is ruled out. The application of magnetic anisotropy as an experimental tool in biology is indicated.
Purification of IMP:Pyrophosphate Phosphoribosyltransferases, Catalytically Incompetent Enzymes in Lesch-Nyhan Disease
Authors: Rubin Charles S. , Dancis Joseph , Yip Lily C. , Nowinski Robert C. , Balis M. Earl 
Published: May 2006

IMP:pyrophosphate phosphoribosyltransferase (IPPase) (EC 2.4.2.8) has been purified over 7000-fold from human erythrocytes. The purified enzyme moved as a single band on disc electrophoresis. Antisera prepared in rabbits and rats against the purified enzyme precipitated and neutralized the enzyme, but had no effect on AMP-pyrophosphate phosphoribosyltransferase (EC 2.4.2.7) activity. Evidence was found for isozymes (enzyme variants) of IPPase in normal erythrocytes.
Erythrocyte lysates of five patients with Lesch-Nyhan disease reacted with antisera against normal IPPase. Lysates from LN erythrocytes blocked the inactivation of normal enzyme by the antibody. LN erythrocytes had about the same concentration of enzyme protein as normal erythrocytes.
The genetic defect in LN results in the production of essentially normal amounts of an immunologically identifiable but catalytically incompetent enzyme. Thus LN is apparently the result of a mutation in a structural gene and is not due to deletion of a structural gene or defect in a regulatory gene.
Initiation and Reinitiation of DNA Synthesis during Replication of Bacteriophage T7
Authors: Dressler David , Wolfson John , Magazin Marilyn 
Published: May 2006

In its first round of replication, the T7 chromosome follows a simple pattern, as viewed in the electron microscope. The iniation of DNA synthesis occurs about 17% from the genetic left end of the viral DNA rod. Bidirectional DNA synthesis from this origin then generates a replicating intermediate that we call an “eye form.” In the eye form, when synthesis in the leftward direction reaches the left end of the viral chromosome, the molecule is converted into a Y-shaped replicating rod. The remaining growing point continues synthesis rightward, until presumably it runs off the right end of the DNA rod, thus terminating replication.
Numerous T7 chromosomes were found in which a second round of replication had begun before the first round had finished. Analysis of these reinitiated DNA molecules showed that the second round of replication, like the first, began 17% from the end of the chromosome and involved bidirectional DNA synthesis.
Regulation of RNA Synthesis in Fibroblasts During Transition from Resting to Growing State
Authors: Mauck John C. , Green Howard 
Published: May 2006

Addition of serum, containing fibroblast growth factors, to a culture of resting 3T6 cells stimulates a transition to the growing state. Studies of ghost monolayers prepared with the aid of detergent at intervals after stimulation showed an increase in the rate of ribosomal RNA synthesis within 10 min. The rate continued to increase for many hours and reached a level 2.5- to 3.5-fold higher by the time DNA synthesis began. The increasing rate of ribosomal RNA synthesis appeared independent of an increase in the number of ribosomal genes, since it was not affected by prevention of DNA synthesis with cytosine arabinoside.
In contrast to ribosomal RNA, the overall rate of transscription of heterogeneous nuclear RNA was not directly affected by serum growth factors and does not appear to be regulated during the transition from resting to growing state. It seems, instead, to be fixed in relation to the amount of template, for it increases proportionally to DNA content.
Oligoclonal IgG Antibody Response in the Central Nervous System to Different Measles Virus Antigens in Subacute Sclerosing Panencephalitis
Authors: Vandvik Bodvar , Norrby Erling 
Published: May 2006

Agarose electrophoresis of cerebrospinal fluid from two patients with subacute sclerosing panencephalitis revealed in both cases several homogeneous bands in the intermediate and basic gammaglobulin region. The bands were identified as IgG with various degrees of kappa or lambda light-chain restriction in crossed immunoelectrophoresis.
Homogeneous IgG bands were separated by preparative agarose electrophoresis and were found to represent measles virus-specific antibodies. Antibody activities against different virus products (hemolysin, hemagglutinin, and nucleocapsids) were carried by different populations of IgG. In both cerebrospinal fluid materials, antibodies to the virus hemolysin and to virus nucleocapsids were found to be relatively more basic than the antibodies to virus hemagglutinin, which appeared in the basic intermediate gammaglobulin region.
We conclude that the oligoclonal IgG bands in cerebrospinal fluid of patients with subacute sclerosing panencephalitis represent homogeneous measles virus antibodies. In some instances, the IgG bands appeared to fulfill criteria of monoclonality on the basis of their electrophoretic homogeneity, selective light-chain type, and specific antibody activity.
5-Bromo-2′-deoxyuridine Potentiation of Transformation of Rat-Embryo Cells Induced
In Vitro
by 3-Methylcholanthrene: Induction of Rat Leukemia Virus gs Antigen in Transformed Cells
Authors: Freeman Aaron E. , Gilden Raymond V. , Vernon Mina Lee , Wolford Ronald G. , Hugunin Patricia E. , Huebner Robert J. 
Published: May 2006

Low-passage rat-embryo cells were not transformed by 3-methylcholanthrene or by 5-bromo-2′ deoxyuridine. However, prior treatment with bromodeoxyuridine, followed by treatment with methylcholanthrene, resulted in cell transformation about three subpassages after removal of the carcinogen. RNA-directed DNA polymerase activity could not be detected in either normal or transformed cells. However, gs-1 antigen specific for rat C-type RNA virus was detected in cultures derived from bromodeoxyuridine-treated cells. No gs-1 antigen for the C-type RNA virus was detected in cultures that had not been treated with bromodeoxyuridine during the 25 subpassages of these experiments.
High-passage rat-embryo cells, derived from a different cell pool, were transformed by either methylcholanthrene or dimethylbenzanthracene without prior infection with an exogenous virus, and without prior treatment with bromodeoxyuridine, gs-1 antigen for C-type RNA virus was also detected in 4 of 4 randomly selected transformed cell lines; the gs-1 antigen was not detected in any of 4 nontransformed control cultures. Considering these and previously published findings, we conclude that the lowpassage cells cannot be transformed by methylcholanthrene because of powerful cellular controls over the endogenous virus. Bromodeoxyuridine triggers some expressions of the endogenous virus; thus, the bromodeoxyuridine-treated cells are more susceptible to the transforming effects of methylcholanthrene. High-passage rat cells do not maintain perfect control over expression of their endogenous virus; the cell cultures are susceptible to the transforming effects of chemical carcinogens.