bluuebunny/crossref_metadata_2025 huggingface dataset:
Human β-D-
N
-Acetylhexosaminidases A and B: Expression and Linkage Relationships in Somatic Cell Hybrids
Authors: Lalley P. A. , Rattazzi M. C. , Shows T. B.
Published: May 2006

Knowledge of the genetic relationships between β-D-
N
-acetylhexosaminidases A and B (EC 3.2.1.30) may help in understanding the hexosaminidase deficiency associated with GM
2
gangliosidosis, a fatal lipid storage disease in man. Through the use of man-mouse somatic cell hybrids we have found that a gene involved in hexosaminidase A expression was linked to the genes coding for mannosephosphate isomerase and pyruvate kinase-3. The gene coding for hexosaminidase B was not linked to any of the genes coding for 25 enzyme markers tested. A combination of immunological and electrophoretic techniques was employed to identify human hexosaminidases A and B with certainty in cell hybrids. Discordant segregation of hexosaminidase A and hexosaminidase B in 60 clones indicated that the genes coding for their expression were not linked. However, hexosaminidase A was never expressed in cell hybrids in the absence of hexosaminidase B. This suggests that the gene responsible for the hexosaminidase A phenotype, linked to mannosephosphate isomerase and pyruvate kinase-3, requires the presence of the gene coding for hexosaminidase B for the expression of hexosaminidase A. These observations offer a genetic explanation for the biochemical and immunological relationships between hexosaminidases A and B and provide the framework for identifying the basic genetic defects responsible for GM
2
gangliosidosis.
Abnormal Precipitation of Oxyhemoglobin S by Mechanical Shaking
Authors: Asakura Toshio , Ohnishi Tsuyoshi , Friedman Shlomo , Schwartz Elias
Published: May 2006

The oxy-form of sickle hemoglobin (Hb S) is abnormally unstable and precipitates at a 10-fold faster rate than does oxyhemoglobin A (oxy-Hb A) during mechanical shaking. The apparent rate of precipitation of heterozygous hemolysate (AS) is approximately half that of oxy-Hb S. The deoxy-form of Hb S, on the other hand, is resistant to the mechanical treatment. This stabilization is attributed to the conformational change of hemoglobin rather than the lack of oxygen, because carbonmonoxide hemoglobin S, which is known to have conformational properties similar to those of oxy-Hb, is unstable even under anaerobic conditions. Methemoglobin S is most unstable, although addition of cyanide stabilizes the protein. The precipitation of oxy-Hb S is inhibited by ethanol and other organic solvents. The relationship of the mechanical instability of sickle oxyhemoglobin to intraerythrocytic denaturation and vaso-occlusive phenomena in sickle cell disease to be determined.
Transcription of Polydeoxythymidylate Sequences in the Genome of the Cellular Slime Mold,
Dictyostelium discoideum
Authors: Jacobson Allan , Firtel Richard A. , Lodish Harvey F.
Published: May 2006

Messenger RNA of the cellular slime mold,
Dictyostelium discoideum
, contains about equimolar amounts of two classes of poly(adenylic acid) [poly(A)]; one is about 25 nucleotides long and the second about 100 nucleotides long. At least half of the messenger RNA molecules contain one sequence each of poly(A)
25
and poly(A)
100
; both poly(A) sequences are located near the 3′ end of messenger RNA, and the kinetics of their appearance on messenger RNA precursor indicates that poly(A)
25
is added before poly(A)
100
.
Dictyostelium
nuclear DNA contains 14,000-15,000 sequences of poly(dT)
25
which could code for the smaller poly(A) residues. The poly(A)
100
must be added post-transcriptionally. The poly(dT)
25
sequences are interspersed throughout the genome and may well represent transcription termination regions.
Immunofluorescence Evidence for the Distribution of Cyclic AMP in Cells and Cell Masses of the Cellular Slime Molds
Authors: Pan Pauline , Bonner J. T. , Wedner H. J. , Parker C. W.
Published: May 2006

With immunofluorescent techniques it has been possible to show that bound cyclic AMP is uniformly distributed in the nucleus and cytoplasm of a number of species of cellular slime molds. One species (which does not respond to cyclic AMP as an acrasin) is an exception and has its cyclic AMP concentrated in the nucleus during the feeding and aggregation stage. In cell masses of
Dictyostelium discoideum
that show early signs of differentiation the anterior, prestalk cells contain more cyclic AMP than the posterior, prespore cells.
Selective Inhibition of Initiating Ribosomes by Spectinomycin
Authors: Wallace Brian J. , Tai Phang-Cheng , Davis Bernard D.
Published: May 2006

Spectinomycin at low concentrations inhibits initiating ribosomes but not ribosomes already engaged in chain elongation. The initiating ribosomes are blocked in some step after formation of the initiation complex, probably the first translocation. Cells inhibited by spectinomycin accumulate polysomes, and these have proved to be unstable polyinitiation complexes: they can be pulse-labeled with methionine but not with valine, and they disappear after addition of rifampicin. Hence, the blocked ribosomes evidently are released and then reinitiate. In heterozygotes this cyclic reinitiation by the sensitive ribosomes, each blocking an initiation site for an average of 10-15 min, can explain (just as with streptomycin) the dominance of sensitivity over resistance.
Muscarinic Cholinergic Binding in Rat Brain
Authors: Yamamura Henry I. , Snyder Solomon H.
Published: May 2006

Binding sites with high affinity and specificity for [
3
H]quinuclidinyl benzilate (QNB) are present in homogenates of rat brain. The characteristics of the binding sites resemble those of muscarinic cholinergic receptors. Specific binding is saturable with respect to [
3
H]QNB and tissue concentration and is time-, temperature-, and pH-dependent. The bimolecular rate of association (2.0 × 10
8
M
-1
min
-1
) and dissociation (1.2 × 10
-2
min
-1
) at 35° indicate a dissociation constant of 60 pM and a density of 65 pmol/g of brain. Muscarinic antagonists and agonists displace specific [
3
H]QNB binding, while nicotinic and non-cholinergic drugs possess little affinity for [
3
H]QNB-binding sites.
The Effect of Azide on Phototaxis in
Chlamydomonas reinhardi
Authors: Stavis Robert L.
Published: May 2006

Phototaxis in
Chlamydomonas reinhardi
was specifically inhibited by azide. The effect of azide was rapid and reversible, and did not depend upon the intensity of actinic light. Under conditions of completely inhibited phototaxis, azide had no effect on the number of motile cells in the population or on the rate of motility. The effect was not related to changes in oxygen uptake or cellular ATP concentration. Apparently, a cellular component or process specifically involved in phototaxis is inactivated by azide.
Formation of Sindbis Virus Capsid Protein in Mammalian Cell-Free Extracts Programmed with Viral Messenger RNA
Authors: Cancedda Ranieri , Schlesinger Milton J.
Published: May 2006

Extracts from Krebs II ascites cells and rabbit reticulocytes effectively synthesize viral proteins with Sindbis viral mRNA isolated from Sindbis-infected BHK cells. The major product is identical to Sindbis capsid protein on the basis of its electrophoretic mobility in sodium dodecyl sulfate-acrylamide gels and two-dimensional tryptic-peptide fingerprints. Various amounts of several additional discrete polypeptides are formed, depending on the components of the cell-free extracts. One of these polypeptides may be a prematurely terminated part of the viral-capsid protein, while another is larger in molecular weight than capsid protein but contains the capsid tryptic peptides. Several of the proteins formed
in vitro
also are detected in extracts of Sindbis-infected BHK cells labeled with [
35
S]methionine.

The three proteins found in Sindbis virions are postulated to originate by proteolytic cleavage from a larger molecular weight polypeptide precursor that is translated from a polycistronic mRNA presumed to contain a single site for initiation of protein synthesis. The two
in vitro
systems appear to translate this polycistronic viral mRNA to yield specific viral capsid although no evidence was found for post-translational proteolysis. Other mechanisms for production of the capsid protein in the cell-free extracts are considered, and some of these may function in the viral-infected cell where unusually large amounts of viral capsid proteins are frequently detected.
Estrogen-Related Increases in Uterine Guanosine 3′:5′-Cyclic Monophosphate Levels
Authors: Kuehl F. A. , Ham E. A. , Zanetti M. E. , Sanford C. H. , Nicol S. E. , Goldberg N. D.
Published: May 2006

Endogenous uterine cyclic GMP and cyclic AMP concentrations were monitored at each stage of the estrus cycle; cyclic GMP concentrations were found to be highest and cyclic AMP concentrations lowest during proestrus when plasma estrogen levels have been shown to be maximal. After administration of estradiol-17β or diethylstilbestrol, the concentrations of uterine cyclic GMP in ovariectomized rats underwent a progressive and significant elevation and the levels of cyclic AMP declined significantly below control values when near maximal accumulation of tissue cyclic GMP was achieved. The increase in uterine cyclic GMP concentrations produced by estradiol benzoate administration was prevented when progesterone and the estrogen were co-administered. These results raise the possibility that an enhanced cellular accumulation of cyclic GMP may be involved in the expression of some of the actions of estrogen in uterine tissue.
Amino-Acid Sequence of an Allotype b4 Light Chain from a Rabbit Antibody to Streptococcal Carbohydrate
Authors: Chen K. C. S. , Kindt T. J. , Krause R. M.
Published: May 2006

The complete amino-acid sequence was determined for a rabbit-antibody light chain of allotype b4. The light chain was recovered from approximately 20 g of homogeneous antibody to group C streptococcal carbohydrate, which was obtained from an immunized rabbit. Several enzymic digestions were used to obtain the overlapping peptides necessary for the sequence determination. The L chain has 210 amino-acid residues, as determined by sequence analysis, and a molecular mass of 23,060 daltons. This antibody light chain contains seven half-cystine residues characteristic of the
κ
B light-chain class. The amino-terminal sequence was determined to be Ala-Asp-Ile-Val-Met, indicating that the chain belongs to the V
κ
I subgroup.
A Conditional Lethal Mutant of
Escherichia coli
K12 Defective in the 5′ → 3′ Exonuclease Associated with DNA Polymerase I
Authors: Konrad E. Bruce , Lehman I. R.
Published: May 2006

A mutant strain of
E. coli
, initially identified by an abnormally high frequency of recombination, has been found to be defective in the 5′ → 3′ exonuclease associated with DNA polymerase I, but not in the polymerase activity. This defect is tolerated at 30°, but is lethal at 43°. Like other polymerase I mutants, the strain is unusually sensitive to methyl methanesulfonate and to ultraviolet irradiation; it is also unable to support the growth of phage λ defective in general recombination, and shows a reduced rate of joining of 10S “Okazaki fragments.” These results demonstrate that a functional DNA polymerase I is essential for normal growth and viability in
E. coli
K12.
Role of Phospholipids in the Multiple Forms of Mammalian Elongation Factor 1
Authors: Legocki Andrzej B. , Redfield Betty , Liu Chen K. , Weissbach Herbert
Published: May 2006

Evidence is presented that high-molecular-weight aggregates of elongation factor 1 from calf brain and liver contain phospholipids. Sucrose gradient analysis has shown that these high-molecular-weight species can be converted to a low-molecular-weight form after incubation with different phospholipase preparations. In addition, a partially purified elongation factor 1 from rabbit reticulocytes is also converted to a low-molecular-weight species by phospholipase treatment. These data indicate that phospholipids are involved in maintaining the integrity of the high-molecular-weight species and support the view that this species is an aggregate of the low-molecular-weight elongation factor 1.
Cleavage of Actin by Thrombin
Authors: Muszbek L. , Laki K.
Published: May 2006

Under certain conditions actin can be split by thrombin. Actin prepared in the presence of excess Ca
++
was found to be resistant to thrombin. However, if actin was purified without added Ca
++
, both G- and F- actin underwent thrombic digestion, although a considerable proportion of actin molecules remained intact. Similar results were obtained with actin (in 50% sucrose) devoid of nucleotide and divalent cations but retaining its native characteristic. The removal of tightly bound Ca
++
from actin by EDTA accelerated the thrombic splitting and made the complete fragmentation of G-actin possible. Thrombin first cleaves actin into two pieces and subsequently one of them, fragment K (molecular weight 37,000 on sodium dodecyl sulfate-polyacrylamide gel), splits further, resulting in fragments L (molecular weight 27,000) and M (molecular weight about 10,000).
Noncovalent Modification of Deoxyhemoglobin S Solubility and Erythrocyte Sickling
Authors: Waterman Michael R. , Yamaoka Kotaro , Dahm Larry , Taylor Joe , Cottam G. L.
Published: May 2006

Ammonium sulfate, as well as potassium phosphate, can be used to measure solubility differences between hemoglobin S and hemoglobin A. In addation, the solubility of deoxyhemoglobin C
Harlem
in 1.96 M phosphate has a markedly different temperature dependence from that of deoxyhemoglobin S. This observation indicates that the solubility measurement is quite sensitive to changes in protein structure. Because of the large degree of comparability between the solubility and the aggregation of deoxyhemoglobin S, solubility was used to measure the effectiveness of organic compounds as noncovalent modifiers of deoxyhemoglobin S aggregation.

Organic solvents (ethanol, dimethylsulfoxide, 1,4-dioxane, dimethylformamide) alter the solubility characteristics of deoxyhemoglobin S in 1.96 M phosphate buffer, pH 7.0. The concentrations of solvent necessary to provide a half-maximal effect are remarkably similar (about 0.5 M), although the chemical nature of these compounds is quite different. The effect of these solvents must be to prevent the noncovalent bond formation necessary to produce the insoluble hemoglobin precipitate, perhaps by altering the water structure around the deoxyhemoglobin S molecules. In addition to these organic solvents, guanidine hydrochloride and urea, two well-known protein denaturants, were studied. Guanidine hydrochloride was as effective as the best organic solvent in increasing the solubility of deoxyhemoglobin S; urea was far less effective. Studies
in vitro
with intact erythrocytes from individuals homozygous for hemoglobin S showed that sickling is decreased up to 50% by treatment with ethanol. This offers further evidence that solubility is monitoring a phenomenon similar to the aggregation of deoxyhemoglobin S inside erythrocytes. While use of these particular compounds
in vitro
would seem to have no clinical implications, these studies do suggest that the use of chemicals that do not modify hemoglobin S covalently should be explored in efforts to prevent deoxyhemoglobin S aggregation.
The Isolation and Characterization of a New Iron-Sulfur Protein from Photosynthetic Membranes
Authors: Malkin Richard , Aparicio Pedro J. , Arnon Daniel I.
Published: May 2006

A new iron-sulfur protein, distinct from the soluble chloroplast ferredoxin, was isolated from chloroplast membranes. The isolated protein, purified to homogeneity, had a molecular weight of about 8000 and 4 atoms of iron and 4 inorganic sulfides per mole. Its absorption spectrum had a broad absorbance band in the 400 nm region, a shoulder at approximately 310 nm, and a peak around 280 nm. The absorbance ratio
A
400
to
A
280
was 0.55. The electron paramagnetic resonance spectrum (measured at 12°K) of the reduced protein was similar to that of other reduced iron-sulfur proteins, showing a major resonance line at
g
= 1.94.

The isolated protein, when photoreduced by spinach chloroplasts, can in turn transfer electrons to mammalian cytochrome
c
. However, the photoreduced protein cannot replace soluble ferredoxin in NADP
+
reduction because of its apparent inability to interact with the chloroplast enzyme, ferredoxin-NADP
+
reductase.

The relation of the isolated iron-sulfur protein to the bound ferredoxin that acts as the primary electron acceptor in Photosystem I is discussed.
In Vitro
Packaging of Satellite Phage P4 DNA
Authors: Pruss Gail , Goldstein Richard N. , Calendar Richard
Published: May 2006

Satellite phage P4 directs the capsid proteins of its helper phage, P2, to form a head which is only one-third the size of the normal P2 head. The P2 head contains a genome of molecular weight 22 × 10
6
, while the small P4 head contains a genome with a molecular weight of only 7 × 10
6
. We have used
in vitro
DNA packaging to test whether P2 and P4 phage head sizes are determined by DNA size.

The small DNA of satellite phage P4 added to a P2-infected cell extract was packaged primarily into particles containing three copies of the P4 genome. This process occurred with approximately the same efficiency as P2 DNA packaging in the same cell extract. In contrast, the large DNA of P2 was packaged 300-fold less efficiently than the small DNA of P4 in an extract derived from P4-infected, P2-lysogenic cells. These results suggest that DNA size is not sufficient to determine head size. The results are compatible with DNA packaging via the filling of preformed empty capsids.
Replication of the
Escherichia coli
Chromosome Following Thymine Starvation
Authors: Liebart J. C. , Buu A. , Marcovich H.
Published: May 2006

The replication of the chromosome of
E. coli
15T
-
(thymine-requiring) has been followed for approximately four generations after a premature initiation of DNA synthesis by thymine starvation. Various labelings of the DNA with
14
C,
3
H, and density media allowed discrimination of the strands preexistent to thymine starvation from those which were made during the subsequent generations. Results were: (
1
) There is very little, if any, DNA degradation following 45 min of thymine starvation. (
2
) The growing points which existed prior to thymine starvation proceeded to the end of the chromosomes after resumption of DNA synthesis and then disappeared. (
3
) The premature DNA synthesis initiated by thymine starvation involved, symmetrically, all free origins; the entire chromosomal population was subjected to this process. (
4
) All the DNA which was synthesized during the progression of the premature growing points was normally replicated, i.e., with no delay or loss, during the next three generations.
Functional Differences in the Multiple Hemocyanins of the Horseshoe Crab,
Limulus polyphemus
L
Authors: Sullivan Bolling , Bonaventura Joseph , Bonaventura Celia
Published: May 2006

Hemocyanin in the hemolymph of the horseshoe crab,
Limulus polyphemus
L., is a high-molecular-weight copper protein which binds oxygen cooperatively and shows a higher oxygen affinity at pH 7 than at pH 9. Treatment with EDTA (ethylenediaminetetra-acetate) disaggregates the hemocyanin molecules and abolishes both the reverse Bohr effect and cooperative oxygen binding. Chloride ions interact with the EDTA-treated material and, in the presence of saturating amounts of NaCl, a reverse Bohr effect is restored, but cooperativity is not. The EDTA-treated hemocyanin contains at least five electrophoretically distinct hemocyanins. These hemocyanins have similar molecular weights (about 66,000) but are functionally dissimilar. They have different oxygen affinities and different responses to chloride ions. The effect of chloride ions on unfractionated hemocyanin is due to pH-dependent chloride interactions with only two of the five hemocyanin components. The functional differences between the hemocyanin components may provide
Limulus
with a valuable respiratory flexibility in its interaction with the environment. The kinetics of oxygen combination and dissociation for the various hemocyanin preparations show that variations in the rate of oxygen dissociation are primarily responsible for the observed differences in oxygen affinity. The rate of oxygen dissociation varies 20-fold under conditions where the apparent rate of oxygen combination shows less than a 2-fold variation. Cooperative interactions in the untreated hemocyanin are most obvious in the “off” reaction, which increases in rate as successive oxygen molecules are released.
Erythropoietic Differentiation in Colonies of Cells Transformed by Friend Virus
Authors: Singer Dinah , Cooper Marvin , Maniatis George M. , Marks Paul A. , Rifkind Richard A.
Published: May 2006

Cells transformed by Friend virus in liquid suspension culture respond to low concentrations of dimethylsulfoxide by initiating hemoglobin synthesis. The kinetics of appearance of such differentiated erythroid cells is consistent with either the induction of differentiation in a uniformly susceptible population of transformed cells or selection for the growth of a distinct erythropoietic subpopulation. The dimethylsulfoxide response of individual colonies of cells transformed by Friend virus grown in semisolid medium was studied in order to distinguish between these alternatives. The data do not support a selective effect of dimethylsulfoxide on the growth of a unique erythropoietic subpopulation; they indicate, rather, that the 745A strain of cells transformed by Friend virus consists of a relatively uniform population of dimethylsulfoxide-sensitive erythropoietic cells.
Membrane Excitability: Made Temperature-Dependent by Mutations
Authors: Satow Youko , Chang Sheng-Yung , Kung Ching
Published: May 2006

Three mutants of
Paramecium aurelia
with genetic lesions at two unlinked loci lost their ability to generate action potentials when grown at high temperatures. Action potentials found at room temperature were slightly aberrant. Kinetics of phenotypic changes after temperature shifts showed that excitation is not immediately sensitive to temperature change in these mutants. The initiation of an action potential must rely on many different gene products (presumably membrane proteins) which are open to modification by conditional as well as unconditional mutations.
Purification and Properties of Mg
2+
-Ca
2+
Adenosinetriphosphatase from
Escherichia coli
Authors: Nelson Nathan , Kanner Baruch I. , Gutnick David L.
Published: May 2006

A procedure for the purification of Mg
2+
-Ca
2+
adenosinetriphosphatase (EC 3.6.1.3) from
E. coli
, yielding relatively large amounts of highly active enzyme, is described. The enzyme consists of four nonidentical subunits. Trypsin treatment of purified enzyme yields a preparation consisting exclusively of the two larger subunits, which are sufficient for ATPase activity. Purified enzyme is inhibited by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole; this inhibition is reversed by dithiothreitol, and the diazole is found preferentially associated with the β-subunit of the enzyme. Antibody prepared against the trypsin-treated enzyme inhibited various ATP-dependent reactions as well as membrane-bound ATPase itself.
Purification and Properties of Reconstitutively Active and Inactive Adenosinetriphosphatase from
Escherichia coli
Authors: Futai Masamitsu , Sternweis Paul C. , Heppel Leon A.
Published: May 2006

The Mg
2+
- and Ca
2+
-stimulated ATPase (EC 3.6.1.3; ATP phosphohydrolase) (bacterial coupling factor) was purified from two strains of
E. coli
by two different procedures: (
a
) method of Nelson, Kanner, and Gutnick [
Proc. Nat. Acad. Sci. USA
(1974) 71, 2720-2724] and (
b
) a modified procedure described in this paper. The ATPase purified from
E. coli
K12 (λ) by the first procedure had 4 subunits (α, β, γ, and ε). It did not bind to a deficient membrane, nor did it reconstitute ATP-driven transhydrogenase activity. Our modified procedure (
b
) yielded 5 subunits (α, β, γ, δ, and ε). This ATPase could bind to a deficient membrane and reconstitute ATP-driven transhydrogenase. This finding suggests that the δ subunit is required for the reaction with the membrane. The molecular weight of the 4-subunit ATPase was significantly lower than that of the 5-subunit ATPase, as judged by equilibrium centrifugation. The specific ATPase activities of both preparations were about the same. These two procedures were also applied to
E. coli
ML308-225.
Distribution of RNA Polymerase Binding Sites in Fractionated Chromatin
Authors: Simpson Robert T.
Published: May 2006

Calf-thymus chromatin was fractionated by ion-exchange chromatography on ECTHAM-cellulose and sucrose gradient sedimentation. [ECTHAM-cellulose is a cationic adsorbent prepared by coupling tris(hydroxymethyl)aminomethane to cellulose with epichlorohydrin.] The capacity of these fractionated chromatins to support RNA synthesis by DNA-dependent RNA polymerase of
Escherichia coli
was examined, using procedures that permit measurement of binding site frequency. Unfractionated calf thymus chromatin has 5-10% as many binding sites as protein-free DNA. By combination of the two fractionation methods, chromatin samples were obtained containing as few as 2% and as many as 47% of the number of binding sites found on protein-free DNA.
Dissipative Structures, Catastrophes, and Pattern Formation: A Bifurcation Analysis
Authors: Nicolis G. , Auchmuty J. F. G.
Published: May 2006

A model chemical network involving reactions and diffusion is studied. Spatially and temporally ordered solutions of the equations are found by bifurcation theory. These solutions are calculated analytically and their stability is studied. Properties of these
dissipative structures
are discussed, and a comparison with Thom's theories of morphogenesis is outlined.
Amplified Ribosomal DNA from
Xenopus laevis
Has Heterogeneous Spacer Lengths
Authors: Wellauer P. K. , Reeder R. H. , Carroll D. , Brown D. D. , Deutch A. , Higashinakagawa T. , Dawid I. B.
Published: May 2006

Eco
R
1
restriction endonuclease makes two cuts in each repeating unit of amplified ribosomal DNA (rDNA) from
Xenopus laevis
. The locations of these cuts have been established by comparison of the secondary structure of single-stranded
Eco
R
1
fragments (as visualized in the electron microscope) with that of
X. laevis
rRNAs and of long strands of uncut rDNA. Of the two classes of fragments generated, the smaller one contains 90% of the 28S rRNA gene, has a duplex molecular weight of 3.0 × 10
6
and is homogeneous in size. The larger class of molecules contains 80% of the 18S rRNA gene and all of the nontranscribed spacer. These latter fragments are heterogeneous with molecular weights ranging from 4.0 to 5.9 × 10
6
. The distribution of sizes within the large class of fragments varies among different preparations of rDNA, and heterogeneity is present in the DNA amplified from the rDNA of a single nucleolar organizer. The heterogeneity is located in the nontranscribed spacer region which is variable in length. This has been demonstrated by the formation of deletion loops in heteroduplexes made between larger fragments of different lengths.
A Cleavage Map of Bacteriophage ϕX174 Genome
Authors: Lee Amy Shiu , Sinsheimer Robert L.
Published: May 2006

Restriction endonucleases isolated from
Hemophilus influenzae, Hemophilus parainfluenzae
, and
Hemophilus aegyptius
were used to cleave ϕX174 replicative form DNA into three sets of specific DNA fragments. The order of these fragments in the ϕX replicative form molecule was determined by (
1
) analysis of partial digest products, (
2
) analysis of overlapping sets of fragments produced by two different restrictive enzymes. On the basis of these results, a detailed physical map of the ϕX174 genome has been constructed with respect to the cleavage sites of all three enzymes.
Met-tRNA
f
Met
Binding to 40S Ribosomal Subunits: A Site for the Regulation of Initiation of Protein Synthesis by Hemin
Authors: Clemens Michael J. , Henshaw Edgar C. , Rahamimoff Hannah , London Irving M.
Published: May 2006

On incubation of reticulocyte lysates at 30° in the absence of added hemin, protein synthesis declines sharply within 4-6 min, due to the action of a translational inhibitor. Partially purified preparations of this inhibitor, in concentrations that inhibit protein synthesis in the lysate, cause reduced binding of Met-tRNA
f
Met
to derived 40S ribosomal subunits in a ribosomal-salt-wash-dependent assay system. Neither the association of salt wash proteins with the subunits nor the level of Met-tRNA
f
Met
bound in preformed 40S complexes is reduced by the inhibitor. No Met-tRNA
f
Met
deacylase activity could be detected in the inhibitor preparation. Protein synthesis in reticulocyte lysates lacking added hemin or containing exogenous inhibitor is maintained by addition of small amounts of an initiation preparation factor, “F-MP,” which may be involved in the binding of Met-tRNA
f
Met
to 40S subunits. This binding constitutes a site for control of protein synthesis by hemin in reticulocytes.
Mechanism of Inhibition of
Bacillus subtilis
DNA Polymerase III by the Arylhydrazinopyrimidine Antimicrobial Agents
Authors: Low Robert L. , Rashbaum Stephan A. , Cozzarelli Nicholas R.
Published: May 2006

Arylhydrazinopyrimidines inhibit DNA synthesis in
Bacillus subtilis
by promoting formation of a specific, long-lived ternary complex with DNA polymerase III and the template-primer DNA. DNA polymerase III contains an associated, single-strand-selective exonuclease which generates 5′-mononucleotides. Drug inhibition of the nuclease similarly proceeds through formation of the ternary complex. The ternary complex was isolated by agarose chromatography. Like inhibition of the nuclease, optimum formation of the complex requires duplex DNA with single-stranded regions such as bacteriophage λ DNA (purely single- and double-stranded DNA are ineffective) and is antagonized by specific deoxyribonucleoside triphosphates. Formation of the ternary complex requires a di- or polyvalent cation and is inhibited by sulfhydryl reagents and high ionic strength. The complex dissociates with a half-life of the order of minutes at 4°.
Increased Collagen Synthesis in Blood Vessels of Hypertensive Rats and Its Reversal by Antihypertensive Agents
Authors: Ooshima Akira , Fuller George C. , Cardinale George J. , Spector Sydney , Udenfriend Sidney
Published: May 2006

Collagen synthesis is increased in the aortas, mesenteric arteries, and to a lesser extent, in the hearts of rats either made hypertensive with desoxycorticosterone acetate-salt or that are spontaneously hypertensive. Several markers of collagen biosynthesis were shown to be increased, including prolyl hydroxylase (EC 1.14.11.2; proline, 2-oxoglutarate dioxygenase), prolyl hydroxylase-related antigen, total collagen content, and the incorporation of [
3
H]proline into total protein and into collagen. The antihypertensive agents chlorothiazide and reserpine, when administered before the onset of hypertension in the rats treated with desoxycorticosterone acetate-salt, prevented or diminished the increase in collagen biosynthesis. When reserpine was given after the onset of hypertension, prolyl hydroxylase activity was decreased concomitant with the decrease in blood pressure. Treatment with reserpine is particularly effective in diminishing arterial prolyl hydroxylase activity.
Photon Propagation Function: Spectral Analysis of Its Asymptotic Form
Authors: Schwinger Julian
Published: May 2006

The physical attitudes of source theory, displacing those of renormalized, perturbative, operator field theory, are used in a simple discussion of the asymptotic behavior of the photon propagation function. A guiding principle is the elementary consistency requirement that, under circumstances where a physical parameter cannot be accurately measured, no sensitivity to its precise value can enter the description of those circumstances. The mathematical tool is the spectral representation of the propagation function, supplemented by an equivalent phase representation. The Gell-Mann-Low equation is recovered, but with their function now interpreted physically as the spectral weight function. A crude inequality is established for the latter, which helps in interpolating between the initial rising behavior and the ultimate zero at infinite mass. There is a brief discussion of the aggressive source theory viewpoint that denies the existence of a “bare charge”.
A Biological Least-Action Principle for the Ecological Model of Volterra-Lotka
Authors: Samuelson Paul A.
Published: May 2006

The conservative model of Volterra for more-than-two predator-prey species is shown to be generated as extremals that minimize a definable Lagrange-Hamilton integral involving half the species and their rates of change. This least-action formulation differs from that derived two generations ago by Volterra, since his involves twice the number of phase variables and it employs as variables the cumulative integrals of the numbers of each species that have ever lived. The present result extends the variational, teleological formulations found a decade ago by the author to the more-than-two species case. The present result is anything but surprising, in view of the works by Kerner, Montroll, and others which apply Gibbs' statistical mechanics to the all-but-canonical equations of the standard Volterra model. By a globally linear transformation of coordinates, the Volterra equations are here converted into a
completely
canonical system isomorphic with the classical mechanics models of Newton, Lagrange, Hamilton, Jacobi, Boltzmann, Gibbs, Poincaré, and G. D. Birkhoff. The conservative nature of the Lotka-Volterra model, whatever its realism, is a crucially necessary condition for the applicability of the variational formalisms, microscopically and macroscopically.
A Small Number of Cistrons for Ribosomal RNA in the Germinal Nucleus of a Eukaryote,
Tetrahymena pyriformis
Authors: Yao Meng-Chao , Kimmel Alan R. , Gorovsky Martin A.
Published: May 2006

The percentage of DNA complementary to 25S and 17S rRNA has been determined for both the macro- and micronucleus of the ciliated protozoan,
Tetrahymena pyriformis
. Saturation levels obtained by DNA·RNA hybridization indicate that approximately 200 copies of the gene for rRNA per haploid genome were present in macronuclei. The saturation level obtained with DNA extracted from isolated micronuclei was only 5-10% of the level obtained with DNA from macronuclei. After correction for contamination of micronuclear DNA by DNA from macronuclei, only a few copies (possibly only 1) of the gene for rRNA are estimated to be present in micronuclei. Micronuclei are germinal nuclei. Macronuclei serve as somatic nuclei during vegetative growth but are destroyed every sexual generation and are reformed from products of meiosis, fertilization, and division of the micronuclei. Thus, the hybridization data suggest that the gene for rRNA must be amplified during macronuclear formation with each sexual generation. These observations also demonstrate that the multiple copies of a repeated gene in a somatic nucleus of a eukaryote can be generated from a small number of copies of that gene in a germinal nucleus.
Diffusion in Polymer Gel Implants
Authors: Davis B. K.
Published: May 2006

Crosslinked polyacrylamide and polyvinylpyrrolidone gels have been used to subcutaneously implant
125
I-labeled immunoglobulin,
125
I-labeled luteinizing hormone,
125
I-labeled bovine serum albumin,
125
I-labeled insulin, [
3
H]prostaglandin F
2α
, and Na
125
I into hamsters. From the rates of absorption of the solutes, their diffusion coefficients were determined. The diffusion coefficients showed a logarithmic dependence on implant polymer concentration and solute molecular weight. Release of the solutes from gel preparations incubated 10 mM phosphate buffer (pH 7.2) at 37° revealed a similar relationship between solute diffusion coefficient, molecular weight, and the concentration of polymer. A general equation was derived that gives the expected diffusion coefficient of a substance in a polymer gel from its molecular weight, diffusion coefficient in solvent, and polymer concentration of the gel.
Partial Purification of Human Interferon by Affinity Chromatography
Authors: Anfinsen C. B. , Bose S. , Corley L. , Gurari-Rotman D.
Published: May 2006

Human interferon prepared by challenge of leukocytes with Sendai virus, or of fibroblasts with double-stranded poly(inosinic acid)·poly(cytidylic acid), has been studied with respect to purification by affinity chromatography. Both leukocyte and fibroblast interferons are removed from crude tissue culture fluids by means of columns of antibody to leukocyte interferon attached to Sepharose-4B. The antibody was prepared in sheep using, as antigen, material that had been partially purified by gel filtration through Sephadex G-100 columns. Many of the impurities in the crude fibroblast interferon were presumably not recognized by the sheep antibodies induced by leukocyte interferon. Fibroblast interferon was, therefore, much more effectively purified as the result of this “common denominator” approach. The fibroblast product, in contrast to interferon from leukocytes, could only be harvested efficiently from the crude starting material when a carrier protein (bovine-serum albumin, and later, cytochrome
c
) was added to the eluting buffers to counteract losses, presumably due to adsorption on purification and assay equipment. Both varieties of interferon exhibit molecular weights of approximately 20,000-25,000, although association with higher molecular weight proteins occurs.
Role of the Polyadenylate Segment in the Translation of Globin Messenger RNA in
Xenopus
Oocytes
Authors: Huez G. , Marbaix G. , Hubert E. , Leclercq M. , Nudel U. , Soreq H. , Salomon R. , Lebleu B. , Revel M. , Littauer U. Z.
Published: May 2006

The translations of native messenger RNA for rabbit globin and that of poly(A)-free globin messenger RNA have been compared after injection into
Xenopus
oocytes. The initial rate of translation of poly(A)-free mRNA is close to that found with intact mRNA. However, at longer incubation periods, the rate of globin synthesis with poly(A)-free mRNA is considerably lower than with native mRNA. Similar differences in the template activity of the two mRNA preparations were found with a cell-free extract of Krebs II ascites tumor. It is concluded that the presence of the 3′ poly(A)-rich sequence in mRNA is required to ensure high functional stability.
Systematics of RNA Tumor Viruses and Virus-Like Particles of Human Origin
Authors: Miller N. R. , Saxinger W. C. , Reitz M. S. , Gallagher R. E. , Wu A. M. , Gallo R. C. , Gillespie D.
Published: May 2006

[
3
H]DNA copies of avian, feline, murine, and primate RNA tumor virus genomes were synthesized
in vitro
by an RNA-dependent DNA polymerase reaction. These DNAs were hybridized to 60-70S RNA that had been purified from the viruses. The amount of the [
3
H]DNA hybridized yielded a measure of the genetic relatedness among the DNA preparations synthesized by the viruses. When many combinations of DNA and RNA were analyzed, the
pattern
of hybridization showed in some cases that the DNA copies of the viral RNA were related to each other in the same way that the natural hosts of the viruses are phylogenetically related. This pattern was observed only among the RNA leukemia viruses. The sarcoma component in sarcoma-leukemia viruses from rats and primates appeared to be unusually closely related. The mouse mammary carcinoma virus and two unclassified viruses (MPMV and Visna) appeared to be genetically distinct.

A similar analysis of DNA synthesized by an RNA-dependent DNA polymerase associated with a viral-like particle obtained from the cytoplasm of human leukemic white blood cells demonstrated that this DNA occupied a space in the affinity pattern of leukemia viruses which is expected of a nucleic acid from a primate-type-C RNA tumor virus. This observation strengthens earlier evidence that components of RNA tumor viruses are associated with human leukemia.
A New Transfer RNA Fragment Reaction: TpΨpCpGp Bound to a Ribosome-Messenger RNA Complex Induces the Synthesis of Guanosine Tetra- and Pentaphosphates
Authors: Richter Dietmar , Erdmann Volker A. , Sprinzl Mathias
Published: May 2006

The tetranucleotide TpΨpCpGp, when bound to
Escherichia coli
50S ribosomal subunits, can replace intact tRNA in the stringent factor-directed synthesis of guanosine tetra- and pentaphosphates. The TpΨpCpGp-dependent fragment reaction has a strict requirement for the 50S and 30S ribosomal subunits and synthetic or natural messenger RNA.
Some Ultrastructural and Enzymatic Effects of Water Stress in Cotton (
Gossypium hirsutum
L.) Leaves
Authors: Da Silva Jorge Vieira , Naylor Aubrey W. , Kramer Paul J.
Published: May 2006

Water stress induced by floating discs cut from cotton leaves (
Gossypium hirsutum
L. cultivar Stoneville) on a polyethylene glycol solution (water potential, -10 bars) was associated with marked alteration of ultrastructural organization of both chloroplasts and mitochondria. Ultrastructural organization of chloroplasts was sometimes almost completely destroyed; peroxisomes seemed not to be affected; and chloroplast ribosomes disappeared. Also accompanying water stress was a sharp increase in activity of acid phosphatase [orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2], and acid and alkaline lipase [glycerol ester hydrolase EC 3.1.1.3] within chloroplasts. Only acid lipase activity was detected inside mitochondria of stressed discs. These alterations in cell organization and enzymology may account for at least part of the previously reported effects of water stress on the CO
2
compensation point, photochemical reactions, and photorespiration.
Ansamycin Biogenesis: Studies on a Novel Rifamycin Isolated from a Mutant Strain of
Nocardia mediterranei
Authors: White Richard J. , Martinelli Edoardo , Lancini Giancarlo
Published: May 2006

A novel ansamycin, rifamycin W, was isolated from a mutant strain of
Nocardia mediterranei
. The metabolic origin of rifamycin W was studied by
13
C nuclear magnetic resonance spectroscopy. Examination of the proton-decoupled pulse and Fourier transform
13
C spectra of rifamycin W biogenetically enriched with [
1
-
13
C]-, [
2
-
13
C]-, and [
3
-
13
C]propionate and with [
1
-
13
C]acetate has revealed that the alignment of
acetate
and
propionate
units corresponds to that previously proposed for rifamycin S. Washed mycelium from a rifamycin B-producing strain of
N. mediterranei
transformed rifamycin W into rifamycin B. We suggest that rifamycin W is a normal intermediate in the biosynthesis of the other rifamycins. These results, together with the structural similarity of rifamycin W to the streptovaricins, reinforce our hypothesis that a common progenitor is involved in the biogenesis of all naphthalenic ansamycins.
Mode of Action of Cholera Toxin: Stabilization of Catecholamine-Sensitive Adenylate Cyclase in Turkey Erythrocytes
Authors: Field Michael
Published: May 2006

Preincubating turkey erythrocytes with cholera toxin alters their adenylate cyclase (EC 4.6.1.1) system: basal activity, maximal epinephrine-stimulatable activity, and affinity of the enzyme reaction for epinephrine are all increased. Pretreatment of erythrocytes with choleragenoid prevents these changes. Cholera toxin does not alter [
3
H]epinephrine uptake by intact erythrocytes. The increase in epinephrine-stimulatable cyclase activity appears to occur at the expense of fluoride-stimulatable activity, which is decreased by the toxin. In lysates from both toxin-treated and control cells, maximally stimulating amounts of epinephrine and fluoride, when added in combination, have a nearly additive effect on cyclase activity. These observations suggest that the adenylate cyclase system of the turkey erythrocyte may exist in two interconvertible forms, one that is catecholamine-responsive but fluoride-insensitive, and another that is fluoride-sensitive but not coupled to catecholamine receptors. Cholera toxin appears to stabilize the enzyme in its hormone receptor-coupled form.
Changing the Actions of Neuroactive Drugs by Changing Brain Protein Synthesis
Authors: Tang Lily C. , Cotzias George C. , Dunn Marina
Published: May 2006

Diminution of cerebral protein synthesis diminished the cerebral responses of mice to some neuroactive drugs, while an increase in synthesis increased the responses. Protein synthesis in whole brains (tested
in vitro
) was diminished by giving living mice different inhibitors by different routes. The inhibitors tested (chloramphenicol, cycloheximide, and puromycin) diminished the behavioral responses of the mice to levodopa without affecting either its cerebral uptake or its conversion to dopamine. A diminution of the reactions of dopaminergic receptors was suggested by the diminished responses to the dopaminergic drug, apomorphine, while participation of cholinergic ones was suggested by experiments with oxotremorine. Proof that receptors had been specifically involved was secured on homogenized caudate nuclei from chloramphenicol-treated mice, in which the dopamine-activated production of cyclic AMP was markedly diminished. A stimulator of cerebral protein synthesis, the artificial double-stranded RNA, poly(I)·poly(C), increased the behavioral responses to these three drugs while it increased the dopamine-activated production of cyclic AMP. Since all these experimental increases or decreases in the responses to drugs required the lapse of only a few hours, proteins with rapid turnover rates must be critical in the activation of several kinds of cerebral receptors.
RNA Polymerase Assembly
In Vitro
. Temperature Dependence of Reactivation of Denatured Core Enzyme
Authors: Harding John D. , Beychok Sherman
Published: May 2006

The
Escherichia coli
RNA polymerase core molecule, after denaturation in 6 M guanidine hydrochloride, can be completely reactivated in the absence of sigma subunit. Reactivation is temperature dependent. At 4° a renatured-inactive preparation is formed that has most of the secondary structure of the original native molecule but has a reduced sedimentation coefficient and a smaller Stokes radius and is, therefore, of lower molecular weight. Upon warming to 37° the renatured-inactive preparation is converted in a time-dependent process to the renatured-active preparation, which has the same amount of secondary structure and same molecular weight as native RNA polymerase. Since the renatured-inactive material is probably composed of subunit assemblies and can be readily reactivated, it should be useful for studying the subunit interactions and control of assembly of RNA polymerase.