bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear Magnetic Resonance Shift Reagents: Evidence for Different Mechanisms of Contact Contributions to
13
C Shifts Induced by Nickel and Cobalt Acetylacetonates with Saturated Amines and Alcohols
Authors: Johns S. R. , Smith Robert A. , Hawkes Geoffrey E. , Roberts John D.
Published: May 2006

The pattern of
13
C and
1
H nuclear magnetic resonance (NMR) shift changes produced by complexation of cobalt and nickel acetylacetonates with amines and alcohols indicates that there is more than one mode of operation of the contact interaction. A large effect with alternating signs is important at the α and β carbons, but this effect seems to be overlaid by another influence that appears to fall off monotonically as one proceeds away from the site of complexation.
An RNA Polymerase Mutation Causing Temperature-Sensitive Sporulation in
Bacillus subtilis
Authors: Leighton T. J.
Published: May 2006

A single-site mutant of
Bacillus subtilis
with a rifampin-resistant RNA polymerase has been isolated; this mutation causes temperature-sensitive sporulation. The temperature-sensitive mutation was only expressed during a limited time period, covering the middle third of the sporulation sequence. Mutant cells grown at the nonpermissive temperature exhibited the normal change in RNA polymerase template specificity, accumulated extracellular proteolytic activity and antibiotic activity, but failed to accumulate alkaline phosphatase and, hence, were blocked at or near stage III in the sporulation sequence. Pulse-labeled RNA synthesis was seriously deranged during postexponential growth phase in mutant cells incubated at the nonpermissive temperature.
Amino-Acid Acceptor Activity of the “70S-Associated” 4S RNA from Avian Myeloblastosis Virus
Authors: Rosenthal Leonard J. , Zamecnik Paul C.
Published: May 2006

The “70S-associated” 4S RNA from avian myeloblastosis virus contains transfer RNA, as determined by aminoacylation. The various amino acids esterified, plus the great number of minor bases found in this “70S-associated” 4S RNA indicate that a sizeable fraction, but not all, of this RNA is transfer RNA.
Deficient DNA Repair in Human Progeroid Cells
Authors: Epstein J. , Williams Jerry R. , Little John B.
Published: May 2006

Skin fibroblasts biopsied from a patient with clinical symptoms of the Hutchinson-Gilford progeria syndrome failed to show evidence of normal DNA strand rejoining
in vitro
after exposure to cobalt-60 gamma irradiation. Control human diploid fibroblasts of fetal origin in early passage, skin fibroblasts of adult origin, and an established line of human liver cells (LICH) all showed essentially complete rejoining of radiation-induced strand breaks within 30 min after irradiation, as evidenced by DNA sedimentation profiles in alkaline sucrose gradients. The results suggest that an enzyme involved in DNA repair may be absent or greatly reduced in efficiency in cells from this patient with the progeria syndrome. Such a repair-deficient cell strain may prove useful in the study of the molecular events associated with x-ray-type damage and its repair in mammalian cells.
Asymptotic Formula for the Coordinates of the Zeros of Sections of the Zeta Function, ζ

N

(
s
), Near
s
= 1
Authors: Levinson Norman
Published: May 2006

The sum, Σ1

N

n
-8
= ζ
N
(
s
),
s
= σ +
it
, is called a section of the Riemann zeta function, ζ(
s
). Here an asymptotic formula, for large
N
, giving the location of the zeros of ζ
N
(
s
) near s = 1 will be demonstrated. In particular these zeros will lie in σ < 1. Relationships between the location of the zeros of ζ
N
(
s
) and the zeros of ζ(
s
) were discovered by Turán. The location in σ < 1 will also be demonstrated directly, without the asymptotic formula, together with results valid also when
s
- 1 is not small.
Proposed Molecular Mechanism for the Action of Molybdenum in Enzymes: Coupled Proton and Electron Transfer
Authors: Stiefel Edward I.
Published: May 2006

The reactions catalyzed by Mo enzymes each find the product differing from the substrate by two electrons and two protons (or some multiple thereof). The coordination chemistry of Mo suggests that there is a distinct relationship between acid-base and redox properties of Mo complexes, and that a coupled electron-proton transfer (to or from substrate) may be mediated by Mo in enzymes. Each of the Mo enzymes (nitrogenase, nitrate reductase, xanthine oxidase, aldehyde oxidase, and sulfite oxidase) is discussed; it is shown that a simple molecular mechanism embodying coupled proton-electron transfer can explain many key experimental observations. In view of this mechanism, the reasons for the use of Mo (from an evolutionary and chemical point of view) are discussed and other metals that may replace Mo are considered.
Conformational Analysis of Thyrotropin Releasing Factor
Authors: Burgess Antony W. , Momany Frank A. , Scheraga Harold A.
Published: May 2006

Conformational energy calculations on thyrotropin releasing factor and on several of its analogues indicate that the central histidyl residue of the native molecule is in an extended conformation. Some derivatives (with a reduced biological activity) have an altered conformation. Since some substitutions leave the conformation unchanged but alter the biological activity, these substitutions must involve the sites responsible for binding of the hormone to its receptor.
Evidence for an Amino-Terminal Extension in High-Molecular-Weight Collagens from Mature Bovine Skin
Authors: Veis Arthur , Anesey Joan , Yuan Leon , Levy Shirley J.
Published: May 2006

Insoluble, mature collagen fibers from bovine skin have been partially solubilized by mild, denaturing, but nonhydrolytic means. The soluble denatured collagen was fractionated by alcohol coacervation, and a fraction rich in high-molecular-weight α-chains was obtained. The heavy α-chains were isolated by carboxymethylcellulose chromatography. Renaturation, followed by measurements of optical rotation at 365 nm, showed that stable, in-register renaturation was more readily accomplished in mixtures of heavy α-chains than in α1-β
11
-chain mixtures. Renatured heavy α-chain preparations were precipitated in SLS form, negatively stained, and examined by electron microscopy. The SLS precipitates were compared with SLS segments from native soluble collagen and were found to match in band pattern and spacing along their entire length from the COOH-terminal region, except for an NH
2
-terminal extension of 170 ± 30 Å in the heavy α-chain SLS. The heavy α-chains correspond chromatographically with those previously reported to be intermediates in the conversion of procollagen to collagen, on the basis of their molecular weight and of labeling studies. The presence of NH
2
-terminal extensions, and their existence in mature insoluble collagen, suggest that these intermediates may have a special role in fibril formation.
Application of the Singular Perturbation Method to Reaction Kinetics
Authors: Richardson W. , Volk L. , Lau K. H. , Lin S. H. , Eyring H.
Published: May 2006

The purpose of this paper is to show how to apply the singular perturbation method to the rate equations in reaction kinetics that involve different time scales. The Lindemann scheme has been chosen for illustration, and the steady-state and equilibrium approximations used in the Lindemann scheme are discussed.
Genetic Fusion of Incompatible Plasmids in
Pseudomonas
Authors: Chakrabarty A. M.
Published: May 2006

The genes specifying enzymes responsible for the degradation of camphor and octane occur on transmissible plasmids in
Pseudomonas putida
strain PpG1 and
P. oleovorans
. Since the presence of the plasmids is vital for the oxidative metabolism of camphor or octane (by the cells) in the absence of other carbon sources, such naturally occurring, energy-generating plasmids have been designated as degradative plasmids. The two degradative plasmids, CAM and OCT, are incompatible with each other and cannot coexist in the same cell. By the use of UV irradiation and suitable selection techniques, it has been possible to fuse these two plasmids so they become part of the same replicon and coexist. Such a technique might be useful in introducing several degradative pathways in the same cell.
Structure-Function Relationships in Lactate Dehydrogenase
Authors: Adams Margaret J. , Buehner Manfred , Chandrasekhar K. , Ford Geoffrey C. , Hackert Marvin L. , Liljas Anders , Rossmann Michael G. , Smiley Ira E. , Allison William S. , Everse Johannes , Kaplan Nathan O. , Taylor Susan S.
Published: May 2006

The binding of coenzyme and substrate are considered in relation to the known primary and tertiary structure of lactate dehydrogenase (EC 1.1.1.27). The adenine binds in a hydrophobic crevice, and the two coenzyme phosphates are oriented by interactions with the protein. The positively charged guanidinium group of arginine 101 then folds over the negatively charged phosphates, collapsing the loop region over the active center and positioning the unreactive B side of the nicotinamide in a hydrophobic protein environment. Collapse of the loop also introduces various charged groups into the vicinity of the substrate binding site. The substrate is situated between histidine 195 and the C4 position on the nicotinamide ring, and is partially oriented by interactions between its carboxyl group and arginine 171. The spatial arrangements of these groups may provide the specificity for the L-isomer of lactate.
A Robust Confidence Interval for Location for Symmetric, Long-Tailed Distributions
Authors: Gross Alan M.
Published: May 2006

A procedure called the wave-interval is presented for obtaining a 95% confidence interval for the center (mean, median) of a symmetric distribution that is not only highly efficient when the data have a Normal distribution but also performs well when some or all of the data come from a long-tailed distribution such as the Cauchy. Use of the wave-interval greatly reduces the risk of asserting much less than one's data will support. The only table required is the usual
t
-table. The wave-interval procedure is definitely recommended for samples of ten or more, and appears satisfactory for samples of nine or eight.
Contact Inhibition of Movement in the Cultures of Transformed Cells
Authors: Guelstein V. I. , Ivanova O. Yu. , Margolis L. B. , Vasiliev Ju. M. , Gelfand I. M.
Published: May 2006

Results of cell-cell collisions were studied with the aid of time-lapse microcinematography in primary cultures of normal mouse-embryo fibroblast-like cells and in cultures of transformed mouse cells of two types: (
a
) primary fibroblast-like cells transformed by Moloney mouse sarcoma virus; (
b
) neoplastic fibroblasts of the CIM strain.

Collisions of normal fibroblast-like cells and CIM cells in mixed cultures were also analyzed. Classification of the results of collisions was based on observation of the movements of the active cell edge during the first hour after the moment when this edge had contacted another cell. Three types of collision results were detected: halt of the active edge, overlapping, and underlapping.

The relative number of overlappings was not higher and that of halts not lower in the cultures of transformed cells as compared with those of normal cells. Analysis of the collisions of normal fibroblasts with transformed cells gave similar results. Thus, the altered morphology of the cultures of these transformed cells cannot be explained by loss of contact inhibition of movement leading to increased ability of cells to move over the surfaces of other cells after collision.
HL-A-Linked Human Immune-Response Genes
Authors: Buckley C. E. , Dorsey F. C. , Corley R. B. , Ralph W. B. , Woodbury M. A. , Amos D. B.
Published: May 2006

Genetic control of the response to specific natural-product antigens has been documented in three informative families. Families were selected on the basis of probands with tuberculosarcoidosis, chronic cutaneous moniliasis, and rheumatoid arthritis. An increased incidence of delayed cutaneous unresponsiveness was observed in each family. Positive associations were identified between HL-A haplotypes and immediate cutaneous hypersensitivity responses to 5, 8, and 11 of 23 test antigens in the three respective families. HL-A-associated differences in averaged responses of cutaneous hypersensitivity were excluded. These significant associations are consistent with linkage between HL-A haplotypes and genes responsible for the immune response to various natural-product antigens.
Self-association of Cholesterol in Aqueous Solution
Authors: Haberland Margaret E. , Reynolds Jacqueline A.
Published: May 2006

Cholesterol has a maximum solubility in aqueous solutions of 1.8 μg/ml or 4.7 μM. It undergoes a thermodynamically reversible self-association with a critical micelle concentration of 25 to 40 nM at 25°. The cholesterol micelle is heterogeneous in size, probably rodlike in shape, and stabilized by an unusually high interaction energy between the aggregated monomers.
Polyadenylation of Maternal RNA of Sea Urchin Eggs After Fertilization
Authors: Wilt Fred H.
Published: May 2006

Between fertilization, or parthenogenetic activation, and the two-cell stage, the content of polyadenylic acid in sea urchin eggs doubles, and the increase occurs primarily in the ribosome-polyribosome fraction. The increase is due to polyadenylation of preexisting RNA molecules synthesized during oogenesis. The polyadenylation occurs in activated, enucleated merogons. It is argued that cytoplasmic polyadenylation may play a role in mobilization of maternal messenger RNA for translation and the polyadenylic acid does not subserve an exclusively nuclear function.
NAD(P) Glycohydrolase Deficiency in Human Erythrocytes and Alteration of Cytosol NADH-Methemoglobin Diaphorase by Membrane NAD-Glycohydrolase Activity
Authors: Frischer Henri , Nelson Richard , Noyes Claudia , Carson Paul E. , Bowman James E. , Rieckmann Karl H. , Ajmar Franco
Published: May 2006

Erythrocytic NADH methemoglobin diaphorase acquires NADH-dichlorophenolindophenol diaphorase activity when enzyme-associated NAD is removed. This transformation is reversible and can be mediated by membrane NAD glycohydrolase (EC 3.2.2.5) in hemolysates as well as in intact cells exposed to hydrogen peroxide. It is abolished either in NADH methemoglobin diaphorase deficiency or in NAD(P) glycohydrolase (EC 3.2.2.6) deficiency which is common in Afro-American but not in European-American adults. Activities of erythrocytic NADP glycohydrolase and NAD glycohydrolase appear to depend on a single membrane enzyme.
Neutron Diffraction Structure of Melampodin: Its Role in the Reclassification of the Germacranolides
Authors: Watkins Steven F. , Fischer Nikolaus H. , Bernal Ivan
Published: May 2006

The precise crystal and molecular structure of melampodin, C
21
H
24
O
9
, was determined from three-dimensional neutron diffraction data collected by counter techniques and phases by direct statistical methods. Crystals are orthorhombic, P2
1
2
1
2
1
,
a
= 8,990(9),
b
= 14.352(14),
c
= 16.294(16) Å, V = 2102 Å
3
, d(calc.) = 1.328 g·cm
-3
, Z = 4 molecules per unit cell. The structural model was refined by full matrix least-squares of 2303 observed independent reflections, with all 54 atoms treated anisotropically, to R(F) = 5.0%. Hydrogen bonds link melampodin molecules together in the solid state. The conformation of the cyclodeca-1,5-diene ring is such that one intraannular hydrogen atom interacts strongly with one double bond, but there is little or no transannular interaction between double bonds. Strain in the ten-membered ring and in the
trans
-fused lactone ring is discussed, as are chemical implications of the unsymmetric epoxide in the epoxyangelic acid side chain. The previously suggested reclassification of germacranolide sesquiterpene lactones into four subgroups is supported, and a new convention for configurational representations of the four subgroups is proposed.
Evidence for Higher Functions of the Cerebellum: Eating and Grooming Elicited by Cerebellar Stimulation in Cats
Authors: Berntson Gary G. , Potolicchio Samuel J. , Miller Neal E.
Published: May 2006

Well-organized eating and grooming behaviors were elicited in cats by stimulation of a zone in the cerebellum that extended from the fastigial nucleus to the superior cerebellar peduncle. Behaviors appeared to result from the facilitation of specific sensorimotor mechanisms, rather than the induction of generalized “drive” states. The results emphasize the need for a broad view of cerebellar function.
Enzyme Loading of Erythrocytes
Authors: Ihler Garret M. , Glew Robert H. , Schnure Frederick W.
Published: May 2006

We demonstrated that β-glucosidase and β-galactosidase can be trapped inside erythrocytes by rapid hemolysis of the cell in the presence of these enzymes. Enzyme enters only during hemolysis, and optimum uptake occurs within 60 sec. There is no loss in cell number after hemolysis-induced enzyme uptake, and the ghosts have only a slightly increased mean cell volume. Smaller proteins enter more readily than larger proteins, although enzymes with a molecular weight of at least 180,000 can be readily entrapped by erythrocytes. This finding may provide a useful approach to the problem of enzyme replacement in certain diseases, including Gaucher's disease.
Alignment of Two DNA Helices: A Model for Recognition of DNA Base Sequences by the Termini-Generating Enzymes of Phage λ, 186, and P2
Authors: Wang James C. , Brezinski Donald P.
Published: May 2006

Based on the 3′- and 5′-terminal sequences of DNA of phage λ, P2, and 186, a model is proposed for recognition of DNA sequences by enzymes responsible for generation of cohesive ends. Two copies of the cohered ends, either on separate molecules or on a concatemer, are aligned with their helical axes parallel but running in opposite directions. The nicking system is dimeric, with each of the two monomers carrying identical sequence-recognition sites. Two pairs of nicks are introduced into the two aligned DNA molecules by the nicking system. The applicability of this model to other biological processes, such as integration of a viral genome into a host genome and the cutting of concatemeric T7 DNA, is discussed.
Inhibition of Three Nucleotide Polymerases by Rifamycin Derivatives
Authors: Thompson Frances M. , Tischler Allan N. , Adams Jesse , Calvin Melvin
Published: May 2006

It is possible to design rifamycin derivatives which can distinguish between viral RNA-instructed DNA polymerase and other nucleotide polymerases.
A New General Estimate of the Rate of Convergence in the Central Limit Theorem in

R
k
Authors: Sazonov V. V.
Published: May 2006

A general theorem is proved which gives an estimate of the rate of convergence on convex sets in the multidimensional central limit theorem for identically distributed summands. The estimate depends on the distance of the boundary of the convex set from the origin (the larger the distance, the better the estimate). The estimate makes sense under minimal requirements on the moments. Furthermore, the dependence on the distribution of a summand in it is in terms of pseudo-moment type quantities which may be small even if the moments are large.
Interaction Between Mendelian and Non-Mendelian Genes. Regulation of the Transmission of Non-Mendelian Genes by a Mendelian Gene In
Chlamydomonas reinhardtii
Authors: Chu-Der Orchid M. Y. , Chiang Kwen-Sheng
Published: May 2006

The non-Mendelian genetic element of a given mating type of
Chlamydomonas reinhardtii
was first doubly marked by succesive mutageneses and then transferred into a number of offspring cells of the opposite mating type. In subsequent crosses of these offspring clones, the transmission pattern of the original non-Mendelian markers was analyzed. The results indicate that the mating-type gene of a given cell regulates the transmission and perhaps the recombination of the non-Mendelian genes regardless of whether the non-Mendelian markers were isolated originally in the same cell or obtained from another cell of the opposite mating type through genetic transmission. The regulation of the transmission of non-Mendelian genes in
C. reinhardtii
is thus apparently different from the autonomous control of the transmission of non-Mendelian mitochondrial genes in yeast by a genetic factor located on the mitochondrial genome.
Qualms Regarding the Range of Validity of the Glansdorff-Prigogine Criterion for Stability of Non-Equilibrium States
Authors: Keizer Joel , Fox Ronald Forrest
Published: May 2006

Doubt is raised concerning the range of validity of a stability criterion for non-equilibrium states which has been proposed by Glansdorff and Prigogine. In the case of a particular autocatalytic reaction, the stability analysis presented by Glansdorff and Prigogine, and by Eigen and by Katchalsky in their reviews of this problem, does not agree with our analysis, which is based upon exact solution of the relevant rate equations. We also find disagreement between the analysis based upon the Glansdorff-Prigogine criterion and our analysis of a second example which involves non-equilibrium steady states. The situation is quite delicate because seemingly innocent approximations (e.g., the use of specialized conditions in the autocatalytic reaction
X
+
Y
⇄ 2
X
discussed in the sequel) may lead to the impression that the scope of validity of the criterion is wider than it actually is. By considering the stability of the equilibrium state, we conclude that the second differential of the entropy, which is at the heart of the Glansdorff-Prigogine criterion, is likely to be relevant for stability questions close to equilibrium only.
Kinetics of Early Changes in Phosphate and Uridine Transport and Cyclic AMP Levels Stimulated by Serum in Density-Inhibited 3T3 Cells
Authors: De Asua Luis Jimenez , Rozengurt Enrique , Dulbecco Renato
Published: May 2006

A kinetic study of the early changes in uridine- and phosphate-transport rates and 3′:5′-cyclic AMP levels induced by the addition of serum to quiescent 3T3 cells revealed that the increase in phosphate uptake and the decrease in the intracellular concentration of 3′:5′-cyclic AMP immediately follow the addition of serum. In contrast, the increase in uridine transport occurred after a lag of several minutes and was clearly preceded by the other changes. The activation of phosphate transport involved an increase in
V
max
, while a more complex pattern was observed for uridine transport. A possible role of phosphate in connection with the other early events was also studied. The addition of phosphate to quiescent cells produced a time-dependent decrease in 3′:5′-cyclic AMP levels and this ion was required for full activation of uridine transport by serum. The results show that the increase in phosphate transport is a primary event in the reinitiation of growth and suggest that the increase in phosphate transport may be connected with subsequent metabolic steps.
Conformational Changes Induced in Dihydrofolate Reductase by Folates, Pyridine Nucleotide Coenzymes, and Methotrexate
Authors: Pastore Edward J. , Kisliuk Roy L. , Plante Laurence T. , Wright John M. , Kaplan Nathan O.
Published: May 2006

Dihydrofolate reductase (EC 1.5.1.3; 5,6,7,8-tetrahydrofolate:NADP
+
oxidoreductase) from antifolate-resistant
Lactobacillus casei
has been isolated in pure form and examined in solution by high resolution proton magnetic resonance spectroscopy. The 220 MHz proton magnetic resonance spectrum of this small enzyme (about 15,000 daltons) consists of several distinct resonance peaks that provide a sensitive nonperturbing probe of its conformational state. Comparison of catalytically active enzyme with preparations denatured in 6 M urea demonstrates dramatically the overall contribution of secondary and tertiary structure to its proton magnetic resonance spectra. More subtle differences existing among several catalytically active enzyme forms may also be readily differentiated by proton magnetic resonance spectroscopy, e.g., the spectra of the ligand-free enzyme and forms containing stoichiometric amounts of tightly bound folate and dihydrofolate, each obtained separately by affinity chromatography, are easily identified. Addition of ligands to these spectroscopically distinct forms may induce changes in their proton magnetic resonance spectra. For example, addition of equimolar dihydrofolate to the apoenzyme converts its relatively featureless aromatic proton magnetic resonance spectrum to one indistinguishable from that of the original enzyme-dihydrofolate binary complex obtained chromatographically. Interaction of the pyridine nucleotide coenzymes NADP
+
or NADPH or of the antifolate Methotrexate with apoenzyme induces additional distinct spectral changes. Enzyme-NADPH and enzyme-Methotrexate binary complexes, which have different aromatic region proton magnetic resonance spectra, are converted to ternary complexes having quite similar spectra by addition of Methotrexate and NADPH, respectively, thus suggesting that an ordered addition of ligands is not required.
Geographical Coincidence of High Heat Flow, High Seismicity, and Upwelling, with Hydrocarbon Deposits, Phosphorites, Evaporites, and Uranium Ores
Authors: Libby L. M. , Libby W. F.
Published: May 2006

Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, high heat flux, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10
-4
of the total of buried biogenic carbon.
Localization of Adenovirus 2 Messenger RNAs to Segments of the Viral Genome Defined by Endonuclease R·R1
Authors: Tal Jacov , Craig Elizabeth A. , Zimmer Stephen , Raskas Heschel J.
Published: May 2006

Adenovirus 2 mRNAs synthesized in productive infection were assigned to specific regions of the genome by hybridization to unique fragments of viral DNA. Radioactive viral RNA synthesized early or late in infection was first fractionated by polyacrylamide gel electrophoresis. Eluted RNAs were then tested for complementary hybrid formation with each of the six fragments of adenovirus 2 DNA generated by cleavage with endonuclease R·R1.

Early RNA species migrating as 13S, 19S, and 20S RNAs were identified as transcription products of fragments A, B, and D, respectively. In addition to the 13S RNA transcribed from A fragment DNA, 13S RNA also hybridized to the D and E fragment DNAs; 11S RNA annealed to both A and B fragments. The RNA that hybridized to fragment C DNA was heterogeneous in size.

Viral RNA synthesized late in infection included 27S, 24S, 19S, and 11S size classes, all of which annealed to A fragment DNA. Additional RNA migrating as 24S hybridized to E and C fragment DNA, and 23S RNA annealed to F fragment DNA.

The results of the hybridizations of size fractionated RNAs with viral DNA fragments enabled formation of a partial map of viral mRNAs with respect to the adenovirus 2 genome. Some of the viral RNAs may represent transcripts which overlap R1 cleavage sites, because in at least three instances hybridization revealed viral RNAs which have the same electrophoretic mobility and anneal to fragments that are contiguous on the genome.
Manipulation of the Phospholipid Composition of Tissue Culture Cells
Authors: Glaser Michael , Ferguson Karen A. , Vagelos P. Roy
Published: May 2006

Methods have been devised to significantly alter the phospholipid composition of LM cells grown in serum-free tissue culture medium. The polar head groups of the phospholipids, as well as the acyl groups of these lipids, can be changed. When LM cells were grown in medium containing choline analogues, either
N
-methyl-ethanolamine or
N,N
-dimethylethanolamine, or the unnatural analogues, 1-2-amino-1-butanol or 3-amino-1-propanol, up to 50% of the cellular phospholipids contained the analogue supplied. When linoleate was added to the cells as a bovine serum albumin complex, up to 40% of the fatty acids of the phospholipids were linoleate. Under the conditions discussed, the polar head group composition, the fatty acid composition, or both together could be varied in the membrane phospholipids.
Room Temperature Phosphorescence and the Dynamic Aspects of Protein Structure
Authors: Saviotti Maria L. , Galley William C.
Published: May 2006

While the phosphorescence of aromatic chromophores in solution is normally quenched through diffusion of dissolved oxygen and other solvent-mediated processes, the phosphorescence of some proteins in solution is observed at room temperature. The tryptophan phosphorescence arises from residues which are hindered from interaction with oxygen by the folding of the polypeptide chains. Measurements of the phosphorescence lifetime of horse liver alcohol dehydrogenase (alcohol: NAD
+
oxidoreductase, EC 1.1.1.1) as a function of oxygen concentration indicate that internal tryptophan residues are periodically exposed to oxygen. This permits the calculation of rate constants for conformational oscillations in the enzyme. The present article illustrates the feasibility of employing phosphorescence in the study of proteins in solution in general and the utility of such experiments in probing the dynamic aspects of protein structure.
The Toxin-Binding Protein of Sugarcane, Its Role in the Plant and in Disease Development
Authors: Strobel Gary A.
Published: May 2006

The toxin-binding protein of sugarcane susceptible to eyespot disease also possesses raffinose-binding activity. The

K
m

's for binding are: helminthosporoside (toxin) 6.8 × 10
-5
M, raffinose 2.5 × 10
-5
M, and melibiose 2.6 × 10
-5
M. Evidence obtained by administering [
14
C]raffinose to sugarcane protoplasts suggests that this protein participates in α-galactoside transport. Cells from a resistant clone of sugarcane do not possess an active-binding protein, and likewise, do not actively take up raffinose. Interestingly, the K
+
, Mg
++
ATPase (ATP phosphohydrolase, EC 3.6.1.3.) on the plasma membrane of the susceptible sugarcane is 30% activated by the toxin at 3 mM. In addition, toxin-treated tissue slices show a rapid uptake of
86
Rb
+
-K
+
which is in agreement with the toxin activation of the membrane K
+
, Mg
++
ATPase. Since the ATPase does not directly interact with the toxin, the activation effect occurs by means of the toxin-binding protein. Membrane proteins may be influenced by the toxin-binding protein acting by one of several different mechanisms.
Applications of the Survival Theory to Ecology
Authors: Freeman D. Carl , Klikoff Lionel G. , Eyring Henry
Published: May 2006

The Eyring-Stover theory of survival developed in earlier papers can be readily applied to a wide diversity of ecological phenomena, with implications for identifying basic responses of organisms to their environment. We report several examples to demonstrate the generality of the theory.
Characterization of the End Groups of RNA of Rous Sarcoma Virus
Authors: Keith J. , Gleason M. , Fraenkel-Conrat H.
Published: May 2006

The 3′ terminus of the 30-35S RNA of Rous sarcoma virus is adenosine. Its amount indicates an average molecular weight for that RNA of about 3 × 10
6
. The 5′ terminus of 30-35S RNA of Rous sarcoma virus was not di- or triphosphorylated, whether isolated by the standard procedure or from virus collected within 3 min of its release from the cells.
Closed Leaves in Foliated 3-Manifolds
Authors: Goodman Sue
Published: May 2006

The purpose of this note is to sketch some results on the existence and properties of multi-holed toral leaves in foliations of closed, orientable 3-manifolds. The complete proofs of these results will appear elsewhere.
On the Chemical Nature of Transfer Factor
Authors: Dressler David , Rosenfeld Steven
Published: May 2006

Two transfer factors prepared in an experimental animal model, the guinea pig, have been tested for their susceptibility to various enzymes of known specificity. The biological activity of these immune response mediators can be destroyed by RNase III, an enzyme that degrades duplex RNA. It, therefore, appears that these transfer factors consist entirely or partly of double-stranded RNA.
Visual Detection of Hepatitis B Antigen
Authors: Giaever Ivar , Laffin Robert J.
Published: May 2006

When the hepatitis B antigen is first adsorbed on a specially prepared metal surface, the subsequent reaction with its specific antibody produces complexes that are visible to the unaided eye. Application of this principle has led to the development of tests for both antigen and antibody that compare favorably with the sensitivity obtained by radioimmunoassay.
Behavior of Three Types of Ribovirus-Like Particles in Segregating Hamster × Mouse Somatic Hybrids
Authors: Yotsuyanagi Y. , Ephrussi Boris
Published: May 2006

An electron microscopic study of somatic hybrids resulting from a cross between hamster melanoma cells harboring R-type particles and mouse fibroblasts harboring intracisternal A-type and (mostly) immature C-type particles was performed. The major findings are: (
a
) hybrid cells that retain a large fraction of both hamster and mouse chromosomes produce all three types of particles; (
b
) the loss of mouse chromosomes is followed by that of intracisternal A- and C-type particles; (
c
) the continued production of A- and C-type particles is dependent on the retention of different mouse chromosomes; (
d
) the mixed intracellular population of R- and A-particles comprises a small number of complex structures in which the two types of virions are enclosed within a common envelope.
Non-Repairable Strand Breaks Induced by
125
I Incorporated into Mammalian DNA
Authors: Painter R. B. , Young B. R. , Burki H. J.
Published: May 2006

When
125
I is incorporated into Chinese hamster DNA (via
125
I-labeled iododeoxyuridine) and the cells are stored at 77°K, the resulting decays of the isotope cause 4 to 5 breaks/single-strand per disintegration. On the average, about 50% of these breaks are repaired. In contrast, under the same conditions of storage and in the same range of total strand breaks/cell, 70-100% of the breaks induced by x-radiation are repaired. Thus, the extreme toxicity of
125
I when incorporated into DNA is correlated with the unrepaired breaks caused by decay of this isotope. These results suggest that unrepaired DNA strand breaks may be important in cell killing after treatments which damage DNA.
Kinetic Constants Determined from Membrane Transport Measurements: Carbonic Anhydrase Activity at High Concentrations
Authors: Donaldson Terrence L. , Quinn John A.
Published: May 2006

Facilitated diffusion rates can be used to determine kinetic constants for rapid reactions occurring within membranes and thin fluid layers. We have applied this technique to the study of the reversible CO
2
hydration reactions catalyzed by carbonic anhydrase (EC 4.2.1.1; carbonate hydro-lyase). The experimental method entails the diffusion of tracer
14
CO
2
through Millipore filter membranes impregnated with aqueous bicarbonate solutions containing various concentrations of dissolved enzyme. A mathematical model of the simultaneous diffusion/reaction transport process is analyzed to predict the effective diffusion rate in terms of the relevant kinetic parameters. The solution to the mathematical model can be transformed to yield straight-line relations analogous to Lineweaver-Burk plots. The pseudo-first-order enzymatic rate constant for the hydration reaction can be determined from the slope or intercept of a plot of this straight-line relationship. Rate constants were accurately measured at high enzyme concentrations for reactions having half-times under a millisecond. The rate constants agree well with other reported kinetic constants for carbonic anhydrase, and the known pH-activity dependence and bicarbonate inhibition are quantitatively demonstrated. The specific activity is constant up to 4.0 mg/ml, which is believed to be the highest concentration at which the activity has been measured. The membrane transport technique has general applicability for other rapid reaction systems.
Differentiation of Lens-Like Structures from Newt Iris Epithelial Cells
In Vitro
Authors: Eguchi Goro , Abe Shin-Ichi , Watanabe Kenji
Published: May 2006

Dissociated cells of pigmented iris epithelium from adult newts grew intensively in monolayer cultures after a lag of two to three weeks. During the lag period, depigmentation occurred in many cells. When cultures became confluent five to six weeks after seeding, many tiny lens-like structures (30-70 per plate) differentiated from dense foci of amelanotic epithelial cells. These lens-like structures appeared in all cultures originated from cells of ventral as well as dorsal iris. The identification of these structures as lens was established by both immunological and ultrastructural techniques.
A New Antitumoral Agent: 9-Hydroxyellipticine. Possibility of a Rational Design of Anticancerous Drugs in the Series of DNA Intercalating Drugs
Authors: Le Pecq Jean-Bernard , Nguyen-Dat-Xuong  , Gosse Charles , Paoletti Claude
Published: May 2006

The designing of DNA intercalating drugs with high DNA affinity in the series of ellipticine has led to a new antitumoral agent, 9-hydroxyellipticine, which has a high DNA affinity, a high activity on L 1210 mice leukemia, and a lack of toxicity at therapeutic dose. The possible correlations among chemical structure, DNA reactivity, and pharmacological activity of DNA intercalating drugs are discussed.
Synthesis of Messenger RNA and Chromosome Structure in the Cellular Slime Mold
Authors: Lodish Harvey F. , Jacobson Allan , Firtel Richard , Alton Tom , Tuchman Jessica
Published: May 2006

This paper summarizes our knowledge of the structure and biosynthesis of messenger RNA in the slime mold
Dictyostelium discoideum
, the arrangement of DNA sequences in the
Dictyostelium
chromosome, and the changes in the pattern of predominant polypeptides synthesized during
Dictyostelium
development.
Genetic Economy of Polyoma Virus: Capsid Proteins Are Cleavage Products of Same Viral Gene
Authors: Friedmann Theodore
Published: May 2006

Two-dimensional tryptic peptide maps of the nonhistone proteins of purified polyoma virus show marked similarities. Protein P
1
is a nondisaggregated, possibly covalent, dimer of the major capsid protein P
2
, whereas P
3
and P
4
share several new peptides as well as many of the peptides derived from P
2
. Extensive use of this kind of processing of viral proteins during the biosynthesis of DNA-containing animal viruses has not been reported previously.
Constitutive Expression of Bacteriophage P2 Early Genes Resulting from a Tandem Duplication
Authors: Bertani G. , Bertani L. Elizabeth
Published: May 2006

A tandem-duplication mutant of bacteriophage P2 was isolated. Physically, its particles are characterized by a higher buoyant density and lower heat stability than the wild type, both consequences of increased DNA content. Genetically, the mutant is easily recognized by its insensitivity to control by the immunity-specific repressor. The duplication covers part of gene B, necessary for phage DNA replication. To explain the immunity-insensitivity of the duplication it is proposed that the promoter, but not the operator site, in the early gene operon is duplicated in this mutant. By crosses with a gene-B mutant, a recombinant carrying a heterozygous duplication was isolated.
Peptide Mapping of Aminoacyl-tRNA Synthetases: Evidence for Internal Sequence Homology in
Escherichia coli
Leucyl-tRNA Synthetase
Authors: Waterson Robert M. , Konigsberg William H.
Published: May 2006

Most aminoacyl-tRNA synthetases contain polypeptide chains of about either 50,000 or 100,000 daltons. Peptide mapping of tryptic, chymotryptic, or
Staphylococcus aureus
acid protease digests of seryl-tRNA synthetase (100,000, dimer) and leucyl-tRNA synthetase (100,000, monomer) from
E. coli
was done after selective modification of lysine residues with [
14
C]succinic anhydride or of methionine residues with [
14
C]iodoacetate. By use of thin-layer electrophoresis and chromatography on silicagel or cellulose plates followed by radioautography it was possible, depending upon the specific activity of the reagent used, to detect radioactive peptides obtained from as little as l μg of protein.

Seryl-tRNA synthetase gave the correct number of tryptic peptides expected for a dimer of identical subunits. Leucyl-tRNA synthetase, on the other hand, gave roughly half the number of radioactive tryptic, chymotryptic, and acid protease peptides expected from the lysine, arginine, and methionine content of the 100,000 monomer. We have interpreted these results as indicating that extensive internal homology exists among lysine- and methionine-containing peptides within the leucyl-tRNA synthetase. The simplest conclusion that can be drawn from these observations is that the NH
2
- and COOH-terminal halves of leucyl-tRNA synthetase and perhaps other synthetases of 100,000 molecular weight may have evolved through a process of gene duplication and fusion, followed by limited diversification by way of amino-acid substitutions accumulating during evolution.
Asymptotic of the Green's Function of a Riemannian Manifold and Ito's Stochastic Integrals
Authors: Malliavin Paul
Published: May 2006

Quantitative estimates are obtained by comparison with ordinary differential equations associated to a subharmonic exhaustion function
q
. We associate with
q
a ratio
a
, which can be considered as the heat flow in an intrinsic time, and the sup and the inf of
a
, namely
a
+
and
a
-
, on the level hypersurfaces of
q
. Then
a
+
and
a
-
define heat flows on the real line. Comparison between the heat flow on the manifold and heat flows on the line are obtained by stochastic integrals.
Initiation Characteristics for the Synthesis of Five T4 Phage-Specific Messenger RNAs
In Vitro
Authors: Natale Peter J. , Buchanan John M.
Published: May 2006

The involvement of the nucleoside triphosphates in the initiation of the synthesis of the messenger ribonucleic acid of five T4 specific enzymes has been studied. Only one of these, the messenger RNA for deoxynucleosidemonophosphate kinase, can be initiated in the presence of one nucleoside triphosphate, namely ATP. All of the remaining four require the presence of at least two nucleoside triphosphates during the initiation period. The combination of ATP and UTP was best for the initiation of messenger RNA for dihydrofolate reductase, ATP and CTP for deoxycytidylate hydroxymethyltransferase and β-glucosyltransferase, and ATP and GTP for α-glucosyltransferase. We have concluded that there is a great variation in the nucleotide composition and sequence of the initiation sites in T4 DNA. No correlation in the requirements of nucleoside triphosphates during the initiation period could be observed among the five systems studied according to their classification as one type or another of “early” T4 messenger RNA.
Mitochondrial Membrane Potential: Evidence from Studies with a Fluorescent Probe
Authors: Tedeschi Henry
Published: May 2006

The fluorescence of the probe 3,3′-dihexyl-2,2′-oxacarbocyanine (CC
6
) has been found to indicate potential across cell membranes. Results obtained in the present study using CC
6
and
Drosophila
mitochondria are in agreement with membrane potentials previously measured by Tupper and Tedeschi using microelectrodes. The results of both studies with
Drosophila
suggest that the potential across the mitochondrial membrane does not play a significant role in oxidative phosphorylation.
In Vivo
Repair of the Single-Strand Interruptions Contained in Bacteriophage T5 DNA
Authors: Herman Ronald C. , Moyer Richard W.
Published: May 2006

Bacteriophage T5 is known to contain several unique single-strand interruptions in only one strand of the duplex DNA. Analysis of labeled parental phage DNA from infected
Escherichia coli
shows that these nicks are repaired
in vivo
to yield intact double-stranded molecules. Sealing begins at about 6 min after infection and is independent of DNA replication. Repair may be an ordered process that starts at a unique end of the molecule.
Role of RNA in Induction of Hepatic Microsomal Mixed Function Oxidases
Authors: Jacob Samson T. , Scharf Martin B. , Vessel Elliot S.
Published: May 2006

Induction of hepatic microsomal cytochrome P-450 and ethylmorphine
N
-demethylase activity by phenobarbital requires
de novo
synthesis of mRNA. Inhibition of RNA synthesis by α-amanitin given up to 8 hr after phenobarbital administration substantially inhibits this induction. However, beyond 8 hr after phenobarbital administration, RNA synthesis is not required for induction of these hepatic microsomal systems. Thus, mRNAs for cytochrome P-450 and ethylmorphine
N
-demethylase appear to be stable. Furthermore, these experiments reveal that the lag period for RNA synthesis approximates the length of the lag period for induction of the hepatic microsomal enzyme systems.
Embryonic Cell Aggregation: Kinetics and Specificity of Binding of Enhancing Factors
Authors: Balsamo Janne , Lilien Jack
Published: May 2006

A new assay for tissue-type-specific adhesive macromolecules is described. This assay measures the binding to whole cells of radioactive macromolecules in aggregation-enhancing supernatants. We show for two tissue types, embryonic chick neural retina and cerebrum, that binding is tissue-type specific. Specific binding can be distinguished from nonspecific binding by its sensitivity to displacement with horse serum and by the kinetics of binding. Specific binding appears to be a cooperative phenomenon.
The Moments of Stochastic Integrals and the Distribution of Sojourn Times
Authors: Nagylaki Thomas
Published: May 2006

For a single diallelic locus in a finite population with any time-independent selection scheme, using the diffusion approximation, a formula is derived in terms of sojourn times for the moments of the integral of an arbitrary function of gene frequency along sample paths. Irreversible mutation and conditioned and unconditioned processes without mutation are treated. From this expression, the differential equation satisfied by the moments follows directly, and the exact probability distribution of sojourn times is deduced. An independent probabilistic proof of the last result based on the properties of time-homogeneous Markov processes is presented.
Requirement of Initiation Factor 3 in the Initiation of Polypeptide Synthesis with
N
-Acetylphenylalanyl-tRNA
Authors: Bernal Samuel D. , Blumberg Benjamin M. , Nakamoto Tokumasa
Published: May 2006

Initiation factor 3 is required, along with initiation factors 1 and 2, for the incorporation of
N
-acetylphenylalanine into polypeptides and the formation of
N
-acetylphenylalanylpuromycin. Initiation factor 3 also strongly stimulates the binding of
N
-acetylphenylalanyl transfer RNA to isolated 30S ribosomal subunits. Phosphocellulose fractions of initiation factor 3 were found to catalyze
N
-acetylphenylalanine incorporation differentially with different synthetic messenger RNAs not containing any codons for
N
-formylmethionine. The results suggest that ribosomes recognize the initiator codon only through the initiator transfer RNA.
Primitive Teratocarcinoma Cells Express a Differentiation Antigen Specified by a Gene at the T-Locus in the Mouse
Authors: Artzt Karen , Bennett Darothea , Jacob François
Published: May 2006

A cell-surface antigen common to mouse primitive teratocarcinoma cells, morulae, and sperm has been shown by serological methods to be specified by a wild-type T-locus gene whose mutant form is lethal in homozygotes at the morula stage.