bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvements in Tests of Long-Range Charge Independence
Authors: Breit G. , Tischler M. , Mukherjee S. , Lucas J.
Published: May 2006

The procedure used to determine the pionnucleon coupling constant
g
2
from multi-energy fits to nucleon-nucleon (
N-N
) scattering data has been shortened without a material loss of accuracy. The
g
2
presetting effect is discussed in connection with the limited accuracy of
g
2
determinations in general and the possibilities of the “optimized polynomial expansions”. The desirability of the Yale graded introduction of one-pion exchange (OPE)-to-“searched” transition energies (

E
tr

) is brought out. Corrections for virtual discontinuities in phase-shift-energy dependence at the

E
tr

decreased the violation of long-range charge independence (LRCI). The effect of two-pion exchange (TPE) has been calculated on the ps theory as ≈ 1 for
g
o
2
(
p-p
) -
g
o
2
(
n-p
),
g
o
2
=
g
2
/
[unk]c;
a result consistent with LRCI. Searching all phase parameters including
g
2
for both isospin values
I
in
g
2
determinations from
n-p
data, but with fixed
I
= 1 non-OPE phases as deduced from
p-p
data in the base search with frozen
g
2
, the OPE effect of the neutral pion, π°, was separated from that of the charged pion, π

c

. The
g
2
for π

c

in
n-p
scattering is determined with much better statistical accuracy than that for π°. The overall
n-p
value of
g
2
is nearly equal to that for π

c

. The results suggest that the distinction between
p-p
and
n-p
values of
g
2
, if present, is in first approximation that arising from the difference between π°-
N
and π

c
-N

couplings. Some limitations on the validity of the conclusions are mentioned.
Model Families of Quadratic Forms
Authors: Morse Marston
Published: May 2006

Let [unk] be the subinterval of
R
of values σ ≤ γ. Let there be given a family
F
of real valued symmetric quadratic forms [Formula: see text] in real variables
z
1
,...,
z
μ
. If for fixed σ[unk][unk] a nonnull μ-tuple
z
is a critical point of
Q
σ
, σ will be called a characteristic root of
F
. When
F
satisfies
Conditions I, II
, and
III
below, the index of
Q
σ
is the “count” of characteristic roots of
F
less than σ.
Analysis of Enzyme Variation in Natural Populations of the Butterfly
Colias eurytheme
Authors: Johnson George B.
Published: May 2006

The use of internal standards in the separation of proteins by gel electrophoresis is shown to offer significant advantages over other control procedures heretofore used in electrophoretic surveys of enzyme variation in natural populations. By the use of such internal standards, a previously undetected class of micro-variability among the enzymes of wild insects has been demonstrated.
Experiments on Osmosis with Magnetic Fluid
Authors: Scholander P. F. , Perez M.
Published: May 2006

Experiments on a ferromagnetic colloidal fluid at equilibrium showed equality between magnetic and osmotic force; this result identifies solute pressure against the free surface as the cause of the negative solvent pressure. Except for water of hydration, there is no other osmotic interaction between solute and solvent.
The Magnetic Field Induced by the Bodily Tide in the Core of the Earth
Authors: Pekeris C. L.
Published: May 2006

The motion in the liquid core of the earth due to the bodily tide can induce a periodic magnetic field having the frequency σ of the tide as well as multiple frequencies, including a steady term. The coupling coefficient for the steady term between the convectively inducing and induced fields is estimated to be of the order of σ
H
2
/λ, where
H
denotes the height of the equilibrium tide, and λ = 1/4πκ, κ denoting the electrical conductivity of the core. With σ = 1.4 × 10
-4
sec
-1
,
H
= 20 cm, and κ = 3 × 10
-6
emu, the coupling coefficient comes out only of the order of 10
-6
, as against unity in the case of the dynamo theory.
The Ages of the Lunar Seas
Authors: Ronca L. B.
Published: May 2006

Two ages are attributed to each circular lunar sea, the age of formation of the circular basin, probably by impact, and the age of the filling of the basin by lava-like effusions.

Each lunar-sea surface displays a range of geomorphic indices. This is interpreted as being due to the presence of effusions of different ages on the surface of each sea. The landing sites of Apollo 11 and 12 have geomorphic indices of value 10.3 and 8.4. The radiometric ages of the rocks are, respectively, approximately 3.65 × 10
9
and 3.36 × 10
9
years. The range of geomorphic indices on sea surfaces is from less than 5 to more than 14, which indicates that the two Apollo crafts landed on surfaces formed about in the middle of the total span of time of sea-surface formation. Using four possible relationships between geomorphic index and age, I conclude that the age of the youngest effusions is less than 3 × 10
9
years and the age of the oldest effusions is more than 4 × 10
9
years. The results of the analyses of the Russian Luna 16 samples, although preliminary, fit in this interpretation.
Cascade Chromatography and Automated Multidimensional Fractionation
Authors: Edelman Gerald M. , Gall W. Einar
Published: May 2006

A general method of automated multidimensional fractionation has been developed. Its basic ingredients are: (
a
) cascade fractionation, i.e., the sequential fractionation of components obtained from each chromatographic dimension on the same or a different dimension, (
b
) on-line acquisition and processing of data at each stage in the fractionation procedure, (
c
) a method for determining the beginning and end of each peak during column elution, and (
d
) automatic linkage of the successive stages in a chemical fractionation scheme based on information obtained before or during each stage. Apparatus for automatic cascade chromatography and conditional fractionation is described. The method can be extended to provide completely automatic separation of pure components from complex mixtures.
Valinomycin-Induced Uptake of Potassium in Membrane Vesicles from
Escherichia coli
Authors: Bhattacharyya Pinakilal , Epstein Wolfgang , Silver Simon
Published: May 2006

Osmotically shocked
Escherichia coli
and membrane vesicle ghosts from
E. coli
cells have lost the ability to accumulate potassium by active transport. The addition of valinomycin to the membrane ghosts restores the capacity to accumulate radioactive
42
K and
86
Rb by a temperature- and energy-dependent process. Membrane vesicles prepared from mutants of
E. coli
altered in potassium transport show defects in the valinomycin-stimulated accumulation of
42
K that are related to the defects in the intact cells.
Cytological Identification of the Chromosome Carrying the IXth Linkage Group (Including H-2) in the House Mouse
Authors: Klein Jan
Published: May 2006

Mus poschiavinus × M. musculus
hybrids, which had seven metacentric chromosomes derived from the
poschiavinus
complement, were repeatedly backcrossed to
M. musculus
and selected for the chromosome carrying the
H-2
complex. A line called T1/Klj was established which had one metacentric chromosome. It was shown by linkage tests and by cytogenetic studies that one arm of this metacentric chromosome corresponds to the
M. musculus
acrocentric chromosome carrying linkage group IX, in which the
H-2
complex is found. The distance from the
H-2
locus to the centromere was tentatively estimated as 14 map units.
Renal Gluconeogenesis in Eviscerated Diabetic Rats
Authors: Smith O. K. , Long C. N. H.
Published: May 2006

Experiments were carried out in eviscerated rats having intact kidneys to examine the effects on body glucose of some conditions known to stimulate overall gluconeogenesis. Preliminary experiments confirmed the enhancing effect of renal ligation on falling blood glucose concentration after evisceration. Adrenodemedullation of alloxan-diabetic rats did not affect blood glucose concentration, but comparison with completely adrenalectomized rats again supported previous conclusions that the adrenocortical hormones, in the presence of the kidneys, maintained the blood glucose at higher concentrations after evisceration. Calculated changes in total body glucose concentration over a 4-hr period after evisceration of several groups of alloxan-diabetic rats with intact kidneys showed that epinephrine, like cortisol, consistently reduced losses of total body glucose compared to the controls. An intravenous infusion of lactic acid so diminished the fall in total body glucose in diabetic rats that changes actually became positive, which indicated a net addition of glucose to the body fluids. Thus, the increased rate of disappearance of blood glucose that follows renal ligation in eviscerated animals results in large part from the interruption of renal gluconeogenesis, and the kidneys as well as the liver must be taken into account when considering the total glucogenic capacity of the body.
Alternative Derivations of the Statistical Mechanical Distribution Laws
Authors: Wall Frederick T.
Published: May 2006

A new approach is presented for the derivation of statistical mechanical distribution laws. The derivations are accomplished by minimizing the Helmholtz free energy under constant temperature and volume, instead of maximizing the entropy under constant energy and volume. An alternative method involves stipulating equality of chemical potential, or equality of activity, for particles in different energy levels. This approach leads to a general statement of distribution laws applicable to all systems for which thermodynamic probabilities can be written. The methods also avoid use of the calculus of variations, Lagrangian multipliers, and Stirling's approximation for the factorial. The results are applied specifically to Boltzmann, Fermi-Dirac, and Bose-Einstein statistics. The special significance of chemical potential and activity is discussed for microscopic systems.
Modification of a Specific Ribosomal Protein Catalyzed by Leucyl, Phenylalanyl-tRNA:Protein Transferase
Authors: Leibowitz M. J. , Soffer R. L.
Published: May 2006

Escherichia coli
ribosomes washed with 1 M NH
4
Cl were found to function as acceptor for leucine and phenylalanine in the reaction catalyzed by leucyl, phenylalanyl-tRNA:protein transferase. When isolated subunits were acylated with [
14
C]phenylalanine and reisolated by gradient centrifugation, the recovered 30S particles had a specific radioactivity nearly 30 times that of similarly treated 50S particles. Autoradiography of gels, which contained protein from acylated 30S particles, that had been subjected to electrophoresis in 8 M urea and in sodium dodecyl sulfate, suggested that acceptor activity was largely due to a single protein with a molecular weight of about 12,000. Leucine and phenylalanine residues that had been transferred to ribosomal protein were reactive with fluorodinitrobenzene and were released as leucyl- or phenylalanylarginine after treatment with trypsin.

The results indicate that leucyl, phenylalanyl-tRNA: protein transferase catalyzes the addition of these amino acids to an NH
2
-terminal arginine residue of a specific ribosomal protein on the 30S subunit.
The “Up-Down” Problem For Operator Algebras
Authors: Pedersen Gert K.
Published: May 2006

It is shown that for any C
*
-algebra
A
of operators on a separable Hilbert space, there is, for each self-adjoint operator x in the strong closure of
A
, a sequence {

x
n

} of self-adjoint operators, each of which is the strong limit of a monotone increasing sequence of self-adjoint operators from
A
, such that {

x
n

} is monotone decreasing and strongly convergent to
x
.
Power Generation and the Environment
Authors: Eliassen Rolf
Published: May 2006

Environmental factors will play an ever-increasing role in planning for the location and design of future power generating plants. This planning must include all phases of furnishing electric power, such as the exploration for and mining of fossil and nuclear fuels; the transportation and storage of these fuels; power plant siting; the disposal of solid wastes from power plants; and the transmission and distribution of electric power. Systems analysis will be of assistance in realistic decision-making and planning. Simulation models can be used to evaluate social, economic, and technological inputs, in order to reach engineering decisions that will assure meeting reasonable environmental standards. Management must look beyond the metropolitan areas presently served by specific electric utilities and must adopt new concepts of both urban and regional planning that will help meet the electric power requirements in the decades ahead and minimize adverse effects on the air, water, and land environment.
Mercurated Dextran Column Chromatography for Fractionating Mononucleotides
Authors: Gruenwedel Dieter W. , Fu Joseph C. C.
Published: May 2006

Mercurated dextran (polysaccharide) was found to fractionate mononucleotides according to their affinity for organomercurial Hg
+
. The nucleotides are released from the chromatographic column in the sequence CMP, AMP, GMP, and TMP when borate buffer of increasing pH is used as an eluent.
The Detection of Ionophorous Antibiotic-Cation Complexes in Water with Fluorescent Probes
Authors: Feinstein M. B. , Felsenfeld H.
Published: May 2006

The binding of alkali cations by the ionophorous antibiotics valinomycin, nigericin, alamethicin, and the macrotetralide actins has been shown to occur, in aqueous media, by the use of the fluorescent probes 1-anilino-8-naphthalene sulfonate and 2-
p
-toluidinyl-6-naphthalene sulfonate. The interaction of the ionophore-cation complexes with the fluorescent dyes produced enhanced fluorescence emission, increased lifetime and polarization, and a significant blue-shift of the emission maxima of the fluorescence spectrum. At constant antibiotic and fluorophore concentrations in water, the intensity of the fluorescence emission was found to be a function of the cation concentration. This permitted relative cation affinities to be determined for alamethicin (Na
+
≅ K
+
), valinomycin (Rb
+
> K
+
> Cs
+
), nigericin (K
+
> Rb
+
> Na
+
> Cs
+
) and trinactin (NH
4
+
> K
+
> Rb
+
> Cs
+
).
New Immunoglobulin-like Molecules in the Serum of Bursectomized-Irradiated Chickens
Authors: Choi Yong Sung , Good Robert A.
Published: May 2006

A new immunoglobulin-like protein that was found in the sera of bursectomized and irradiated chickens is reported. Unlike IgM and IgG, this protein is apparently made only of heavy chains of IgM and contains no light chains.
Control by Cesium and Intermediates of the Citric Acid Cycle of Extracellular Ribonuclease and Other Enzymes Involved in the Assimilation of Nitrogen
Authors: Holloman William K. , Dekker Charles A.
Published: May 2006

Synthesis of extracellular ribonuclease is induced in cell cultures of
Ustilago sphaerogena
that are starved for nitrogen and exposed to the gratuitous inducer, 6-mercaptopurine. Cesium, ammonium, or alkylammonium ion represses ribonuclease induction. Addition of citric-acid cycle intermediates to cesium ionrepressed cultures partially restores the rate of ribonuclease synthesis to the induced level. Enzymes involved in assimilation of nitrogen from different sources are also repressed by cesium ion and derepressed by intermediates from the citric acid cycle.
Detection of Avian Tumor Virus-Specific Nucleotide Sequences in Avian Cell DNAs
Authors: Varmus Harold E. , Weiss Robin A. , Friis Robert R. , Levinson Warren , Bishop J. Michael
Published: May 2006

The effect of unlabeled cellular DNA upon the reassociation kinetics of labeled double-stranded DNA made by DNA polymerase from avian tumor viruses has been used to measure virus-specific nucleotide sequences in cells. Multiple copies of these sequences were found equally in normal chick cells, in chick cells transformed in culture, and in Rous tumor cells. Copies were also present equally in cells harboring chick helper factor and group-specific antigen, and in cells lacking those characteristics. Quail DNA also contains multiple copies of these sequences, but no copies were detected in HeLa-cell DNA or salmon-sperm DNA.
Evolution in Columbidae: Additional Relationships Among the Antigenic Specificities Produced by Gene Interaction
Authors: Irwin M. R.
Published: May 2006

Two of the antigenic characters of erythrocytes, that in either identical or related forms differentiate four species of Streptopelia (
chinensis, humilis, orientalis
, and
senegalensis
) from a fifth (
S. risoria
) by interaction of the causative genes, are involved in the appearance in backcross hybrids of additional antigenic specificities to those of the parental species. The cells of backcross hybrids, resulting from matings of
S. chinensis
x
S. risoria
and backcrossing to
S. risoria
, in which the two independently inherited antigenic characters (
ch
-4 and
ch
-8 peculiar to
S. chinensis
) are combined as homozygotes, exhibit an antigenic specificity not present in backcross birds carrying separately these two characters. This result indicates an interaction within
S. chinensis
of the genes for these two antigenic characters.

An antigen (C
g
) by which
Columba guinea
differs from
C. livia
has behaved as a unit in over 400 backcross offspring. It is antigenically related to both
ch
-4 and
ch
-8 of
S. chinensis
. It is also related to, but not identical with, this interaction antigen of
S. chinensis
. Further, the C
g
character is also related to an interaction product that appears in all backcross offspring carrying the group-4 antigen in a
S. risoria
genome.

Genes related to those that in modern species or in species hybrids interact to effect new antigenic specificities presumably possessed the same abilities in ancestral forms of Columbidae.
Structural and Functional Characterization of Isolated Pancreatic Exocrine Cells
Authors: Amsterdam A. , Jamieson J. D.
Published: May 2006

Viable isolated exocrine cells have been obtained from guinea-pig pancreas by a tissue dissociation procedure using crude collagenase (EC 3.4.4.19) and hyaluronidase (EC 3.2.1.35), chelation of divalent cations, and mild shearing forces. Cell yields are 50-60%, based on recovered DNA, and about 90% of the population consists of exocrine cells which, although rounded up, retain their
in situ
polarity with regard to regional distribution of zymogen granules and specialization of the former luminal plasmalemma. The isolated cells incorporate labeled amino acids into proteins at linear rates for at least 4 hr at levels comparable to pancreatic slices
in vitro;
more than 95% of the exocrine cell population is active in this process, as shown by autoradiography. In response to secretogogues at optimal doses (100 μM carbamylcholine; 0.1 μM pancreozymin, or 0.01 μM caerulein), the cells discharge up to 30% of their content of pulse-labeled secretory proteins to the medium over a 3-hr period; in the same time, the controls release about 5% of their content. The results indicate that isolated exocrine cells are capable of synthesizing the processing secretory proteins, and of responding directly to cholinergic and peptidic secretogogues.
Hybridization of Variants of Chloramphenicol Acetyltransferase Specified by
fi
+
and
fi
-
R Factors
Authors: Shaw William V. , Sands Linda C. , Datta Naomi
Published: May 2006

An
fi
-
type of R factor for transferable chloramphenicol resistance carries the structural gene for a novel species of chloramphenicol acetyltransferase (EC 2.3.1.99). The enzyme associated with the
fi
-
plasmid is distinct from that described for
fi
+
R factors. The
fi
+
- and
fi
-
-related variants of chloramphenicol acetyltransferase were hybridized
in vivo
and
in vitro
. Both techniques yielded only a single symmetrical heteromeric species rather than the three (A
3
B
1
, A
2
B
2
, and A
1
B
3
) hybrids predicted from the tetrameric (identical monomers) structure of chloramphenicol acetyltransferase.
Adenovirus-2 DNA Contains an Inverted Terminal Repetition
Authors: Wolfson John , Dressler David
Published: May 2006

Denaturation and renaturation of the adenovirus-2 chromosome (a duplex rod) generates single-stranded circles of unit length. These circles can be opened into linear DNA molecules by digestion with exonuclease III, indicating that hydrogen bonding between the two ends of an adenovirus strand is responsible for maintaining the rod in a circular state.

The formation of adenovirus single-stranded circles, and their sensitivity to exonuclease III, indicate that the mature adenovirus-2 DNA molecule contains an inverted terminal repetition. That is, the base sequence at one end of the molecule is inverted and appears again at the other end of the molecule. This is the first example of such a structure, and its function is unknown.
Structure of the Radical Form of Clostridial Flavodoxin: A New Molecular Model
Authors: Andersen R. D. , Apgar P. A. , Burnett R. M. , Darling G. D. , Lequesne M. E. , Mayhew S. G. , Ludwig M. L.
Published: May 2006

Interpretation of a new electron-density map at 3.25-Å resolution has led to a somewhat revised model for the free radical (semiquinone) structure of flavodoxin from
Clostridium MP
. Although the general conformation of the molecule is very similar to that of oxidized
Desulfovibrio vulgaris
flavodoxin, flavin mononucleotide-protein interactions are not identical in the two flavodoxins. In the
Cl. MP
semiquinone molecule, the isoalloxazine ring appears to retain the essentially planar conformation characteristic of oxidized flavins; within the limits imposed by the resolution of the data, the map shows no evidence for bending of the isoalloxazine ring about N5-N10.
In Vitro
Repair of X-Irradiated DNA Extracted from
Bacillus subtilis
Deficient in Polymerase I
Authors: Laipis Philip J. , Ganesan A. T.
Published: May 2006

DNA extracted from x-irradiated cells of a mutant of
Bacillus subtilis
deficient in DNA polymerase I has greatly reduced biological activity. This DNA, which has many single-strand nicks, can be repaired
in vitro
with purified DNA polymerase I and DNA ligase or with lysates of wild-type
B. subtilis
cells, which restore biological activity and increase the single-strand molecular weight. Lysates of polymerase I-deficient
B. subtilis
cells cannot repair such irradiated DNA until purified DNA polymerase I or lysate from wild-type cells is added to the deficient lysate.
One-Parameter Equation of State for Metals and Certain Other Solids
Authors: Libby L. M. , Libby W. F.
Published: May 2006

A general isothermal equation of state for metals and certain other solids [Formula: see text] Where
BT
0
is the bulk modulus at zero pressure,
P
is the pressure, and
V
0
and
V
are the volumes at zero pressure and pressure
P
, respectively, has been discovered empirically. The fit to a straight line for twenty metals and twelve metallic halides is within a few percent mean deviation. The rationale leading to this particular relation is that of the Virial Theorem, as applied to those solids for which the potential energy scales as the mean inverse of the inter-atomic distance, and for which on compression the entropy change is small.
Algebraic Structure of Linear Dynamical Systems. III. Realization Theory Over a Commutative Ring
Authors: Rouchaleau Yves , Wyman Bostwick F. , Kalman R. E.
Published: May 2006

The realization theory linear dynamical systems, previously developed over a field, are extended to a large class of commutative rings. The principal result is that the existence criterion for a finite realization extends without modification from a field to a Noetherian integral domain.
The Dynamics of Life: Aging
Authors: Eyring Henry , Stover Betsy J.
Published: May 2006

Biologic aging arises from various causes, including deterioration of cells by mutations, destruction of the cells in organs through infections, aging by failure to eliminate harmful waste products, poisoning from external sources, and by radiation damage. All of these processes lead to equations of the kind observed experimentally for the aging process, so that a proper assessment of the various factors contributing to aging is especially complicated. Many nonbiological processes in which the products of reaction speed up the aging reaction lead to the familiar equation for the rate of aging. Corrosion of metals is exhibited as a typical example of this; many other examples could be given. The general equation for depth of anesthesia brought about by lipid-soluble materials and how this effect can be mimicked by accumulation of waste products is shown to simulate the typical aging curve; it is well known that such waste products are a frequent cause of death.
Systematics for Elastic Scattering of Elementary Particles
Authors: Libby Leona M.
Published: May 2006

The function (
do/dlnt
)
½
against (
t
)
½
gives rise to a scaling law for elastic scattering of elementary particles on protons, for barycentral angles from 0 to 90°, and for laboratory momenta from 5 to 25 GeV/c.
Nucleotide-Dependent Inactivation of RNA Polymerase from
Bacillus brevis
Authors: Sarkar Nilima , Paulus Henry
Published: May 2006

RNA polymerase has been purified from vegetative cells of
Bacillus brevis
and resolved into “core” enzyme and sigma factor. The purified enzyme is rapidly inactivated by incubation at low temperatures in the presence of 1-2 mM ATP, dATP, or NAD
+
, while other nucleotides at this concentration have little or no effect. Inactivation is not accompanied by the incorporation of an adenylyl or phosphoryl moiety into RNA polymerase; nevertheless, it is essentially irreversible. DNA, high concentrations of glycerol, as well as low concentrations (1 mM) of orthophosphate protect RNA polymerase from the nucleotide-dependent inactivation.

A similar inactivation of RNA polymerase in the presence of ATP is observed with crude preparations from
Bacillus subtilis
and
Bacillus polymyxa
. This phenomenon may represent a novel mode of regulation of transcription that does not involve a covalent modification of RNA polymerase or its interaction with other protein factors, but rather is due to a structural transition to an inactive form induced by small molecules.
Altered Sequences Changing the Operator-Binding Properties of the
Lac
Repressor: Colinearity of the Repressor Protein with the
i
-Gene Map
Authors: Weber Klaus , Platt Terry , Ganem Don , Miller Jeffrey H.
Published: May 2006

A technique is described for mapping point mutations in the first 59 amino-acid residues of the
lac
repressor from
Escherichia coli
, using less than 0.1 μmol (4 mg) of the purified protein. This technique was used to localize five mutations affecting the ability of the
i
-gene product to repress
in vivo
. These alterations are located at four different sites in the amino-terminal region of the repressor molecule. Three of these are missense mutations and result in changes from serine to proline (residue 16), threonine to alanine (residue 19), and alanine to valine (residue 53). Each amino-acid substitution alone is sufficient to eliminate repression
in vivo
, presumably by altering the operator binding activity. The remaining two independently-isolated mutations are identical, and result in a change from a glutamine codon at position 26 to an amber (UAG) codon. Since suppression of this nonsense mutation with amber suppressors that insert leucine, tyrosine, serine, or glutamine restores repressor activity to the molecule, glutamine
26
cannot be crucial for the operator-binding function. A comparison of the position of each altered residue with the genetic map enabled us to estimate the physical distance between several deletion-group endpoints.
Evolution of Neurophysin Proteins: The Partial Sequence of Bovine Neurophysin-I
Authors: Capra J. D. , Kehoe J. M. , Kotelchuck D. , Walter R. , Breslow E.
Published: May 2006

The sequence of the first 50 amino-acid residues of bovine neurophysin-I was determined. A comparison of this sequence with that of the 97-residue bovine neurophysin-II and the 92-residue porcine neurophysin-I molecules reveals a high degree of homology among these proteins. It is suggested that the binding site of neurophysin proteins for neurohypophyseal hormones is located in the middle portion of these molecules, where their sequences are virtually identical. The sequence data, as well as the occurrence of at least two neurophysins in both the pig and the cow, suggest that each species inherited at least two structural genes controlling the synthesis of these proteins. The most striking finding in the study was the observation of internal sequence homologies within the neurophysins. This result implies that these molecules arose by way of a series of partial gene duplications of a primitive gene that coded for a smaller ancestral protein.
Airey's Converging Factor
Authors: Murnaghan Francis D.
Published: May 2006

Asmptotic series for the calculation of functions, for values of the argument numerically >1, start off with terms whose numerical values decrease but, at a certain stage, the terms begin to increase in numerical value and must be ignored. At this stage, there may be two adjacent terms of equal numerical value; when the
least
term of the asymptotic series is spoken of, it is in reference to the first of these two terms. The sum of the initial terms of the asymptotic series up to, and including, the least term often furnishes a fair approximation to the desired value of the function being evaluated. It was early observed by computers that if the terms of the asymptotic series alternate in sign, this approximation was often improved by replacing the least term by its half. The factor by which the least term of the asymptotic series must be multiplied so that the true value of the function being evaluated is obtained by addition of this
modified
least term to the remaining initial terms of the asymptotic series is known as the
converging factor
for the asymptotic series. The converging factor for the asymptotic series involved in the calculation of the exponential integral, for large negative values of the argument, was given as a power series in the reciprocal of the argument by Airey; the first term of this series is ½. A method for the determination of the coefficients of this series is given.
Calcium Ions and the Cardiotonic Action of Glucagon
Authors: Visscher Maurice B. , Lee Y. C. P.
Published: May 2006

The positive inotropic action of glucagon on the cat heart is dependent upon the extracellular Ca concentration. The inotropic effect is proportionately greater, the lower the concentration of Ca in the perfusate (above zero, at which glucagon is without significant effect). Nevertheless, Ca influx (as measured with
45
Ca) into the myocardium is not demonstrably influenced by glucagon, except at 0.09 mM Ca, where the interpretation of the effect is complicated by the fact that there is mechanical asystole at that Ca concentration in the absence of glucagon, while excitation-contraction coupling still occurs when the hormone is added. The possibility is suggested that glucagon may influence intracellular movement of Ca, even when its transmembrane movement is affected only slightly.
Evidence for Conversion of Heteroduplex Transforming DNAs to Homoduplexes by Recipient Pneumococcal Cells
Authors: Roger Muriel
Published: May 2006

Heteroduplex molecules of pneumococcal DNA, prepared by cross-annealing resolved complementary strands, have been used as donors in transformation. A number of pairs of genetic markers are situated exclusively in the
trans
configuration in these heteroduplexes. Insertion of two markers from
trans
configuration into opposite DNA strands of a recipient genome should result in their segregation after one replication cycle. As a consequence, doubly transformed progeny would not appear, or would be markedly decreased. Contrary to these expectations, transformations with the heteroduplex DNAs give as many doubly transformed progeny for unlinked marker pairs as do homoduplex DNAs. For a pair of markers that normally are weakly linked, the frequencies of cotransfer are actually greater than those observed for a mixture of two singly marked homoduplex DNAs. These results lead to the conclusion that the heteroduplex DNAs are acted upon by repair enzymes of recipient cells so that markers introduced in the
trans
configuration are frequently converted to the
cis
configuration, either before or during integration. The efficiency of this conversion suggests that the repair and integration processes may be intimately connected. It is also concluded that complete breakdown of one strand of donor heteroduplex DNA does not occur during DNA uptake by recipient cells.
Holomorphic Embedding of Complex Curves in Spaces of Constant Holomorphic Curvature
Authors: Chavel Issac , Rauch Harry E.
Published: May 2006

A special case of Wirtinger's theorem asserts that a complex curve (two-dimensional) holomorphically embedded in a Kaehler manifold is a minimal surface. The converse is not necessarily true. Guided by considerations from the theory of moduli of Riemann surfaces, we discover (among other results) sufficient topological and differential-geometric conditions for a minimal (Riemannian) immersion of a 2-manifold in complex projective space with the Fubini-Study metric to be holomorphic.
Nature of Oxygen Inhibition of Nitrogenase from
Azotobacter vinelandii
Authors: Wong Peter P. , Burris R. H.
Published: May 2006

The reduction of nitrogen, acetylene, azide, and cyanide at various oxygen concentrations by nitrogenase from
Azotobacter vinelandii
was measured with a well-defined system. Oxygen inhibited the reduction of each substrate uncompetitively. The inhibition constants (
K
i
) were 0.014, 0.023, 0.008, and 0.003 atm of oxygen for reduction of nitrogen, acetylene, azide, and cyanide, respectively. The system used included ATP-generating components, subcellular particles from
A. vinelandii
with high nitrogenase specific activity, and illuminated spinach chloroplasts plus carriers to supply electrons. Oxygen did not affect the photochemical electron donating system, but it did inhibit nitrogenase-dependent ATP hydrolysis.
The RNA Tumor Viruses—Background and Foreground
Authors: Temin Howard M.
Published: May 2006

The members of the RNA tumor virus (or leukovirus) group of animal viruses replicate via a DNA intermediate and transmit their information stably in cells as DNA. Although some of these viruses are capable of inducing neoplastic transformation, others are not. These viruses may be related to spontaneous neoplasia, but the relationship is that of analogy rather than etiology. The relationship of these viruses to human disease is unknown. Two models of spontaneous neoplasia that involve either activation of the information of a transforming RNA tumor virus or the creation of information for neoplastic transformation by recombination involving information transfer from RNA to DNA are being tested in model systems.
Long-Lived Conformation Changes Induced by Electric Impulses in Biopolymers
Authors: Neumann Eberhard , Katchalsky Aharon
Published: May 2006

Electric impulses are capable of inducing long-lived conformational changes in (metastable) biopolymers. Results of experiments with poly(A)·2 poly(U) and ribosomal RNA, which are known to develop metastabilities, are reported. A polarization mechanism is proposed to explain the structural transitions observed in the biopolymers exposed to the impulses. In accordance with this idea, the applied electric field (of about 20 kV/cm and decaying exponentially, with a decay time of about 10 μsec) induces large dipole moments by shifting the ionic atmosphere of multistranded polynucleotide helices. This shift, in turn, causes strand repulsion and partial unwinding. The fields used in our experiments are of the same order of magnitude as those in nerve impulses. The significance of the impulse experiments with regard to the question of biological memory recording is briefly discussed.
T4 Transfer RNAs: Codon Recognition and Translational Properties
Authors: Scherberg Neal H. , Weiss Samuel B.
Published: May 2006

T4 phage transfer RNAs recognize the previously assigned codons for a given amino acid; however, they tend to prefer code words that are less well recognized by their host. The phage transfer RNAs are more effective in polypeptide synthesis with T4 rather than
Escherichia coli
messenger RNAs.
A Class of Bounded Pseudo-Differential Operators
Authors: Calderón Alberto P. , Vaillancourt Rémi
Published: May 2006

Pseudo-differential operators of order -M and type ρ, δ
1
, δ
2
are shown to be bounded in L
2
provided that 0 ≤ ρ ≤ δ
1
< 1, 0 ≤ ρ ≤ δ
2
< 1, and [Formula: see text].
Nonmathematical Concepts of Selection, Evolutionary Energy, and Levels of Evolution
Authors: Darlington P. J.
Published: May 2006

The place of mathematics in hypotheticodeductive processes and in biological research is discussed. (Natural) Selection is defined and described as differential elimination of performed sets at any level. Sets and acting sets are groups of units (themselves sets of smaller units) at any level that may or do interact. A pseudomathematical equation describes directional change (evolution) in sets at any level. Selection is the ram of evolution; it cannot generate, but can only direct, evolutionary energy. The energy of evolution is derived from molecular or chemical levels, is transmitted upwards through the increasingly complex sets of sets that form living systems, and is turned in directions determined by the sum of selective processes, at different levels, which may either supplement or oppose each other. All evolutionary processes conform to the pseudomathematical equation referred to above, use energy as described above, and have a P/OE (ratio of programming to open-endedness) that cannot be measured, but can be related to other P/OE values. Phylogeny and ontogeny are compared as processes af directional change with set selection. Stages in the evolution of multi-cellular individuals are suggested, and are essentially the same as stages in the evolution of some multi-individual insect societies. Thinking is considered as a part of ontogeny involving an irreversible, nonrepetitive process of set selection in the brain.
Light-Induced Fluorescence Changes in
Chlorella
, and the Primary Photoreactions for the Production of Oxygen
Authors: Mauzerall David
Published: May 2006

The light-induced increases of the effective fluorescence yield in
Chlorella
are too slow to be primary processes in photosynthesis. The fast transient state (risetime 25 nsec, limited to the first flash) is attributed to a priming reaction for the photosystem that makes oxygen. The slower cyclical process (risetime 3 μsec, decay time 200 μsec and 2 msec) is attributed to the dark reactions that make oxygen after photoexcitation of this system. The slower cyclical process is also distinguished by a narrower emission spectrum that peaks at a shorter wavelength than the dark adapted or fast transient state. A minimum of six different fluorescent states are required to explain the data. In addition to the usual assumption about changing quantum yield of fluorescence in these processes, the data suggest that changes in cross section of optical absorption must also be considered. The slowest relaxation times observed (0.2-2 msec) are well correlated with the slow steps detected in evolution of oxygen.
Unexpected Resistance to X-Irradiation in a Strain of Hybrid Mammalian Cells
Authors: Little John B. , Richardson U. Ingrid , Tashjian Armen H.
Published: May 2006

The radiosensitivities of a strain of mouse fibroblasts (Cl-1D), of rat pituitary cells (GH
1
2C
1
), and of a hybrid between the two (α-RST) have been studied. Their mean chromosome numbers were 50, 70, and 111, respectively. The hybrid cells were much more resistent to radiation than either of the parent strains. The range of the D
0
(reciprocal of the slope, and therefore a measure of radiosensitivity) for the linear portion of the survival curves for each cell line was: Cl-1D, 134-142 R; GH
1
2C
1
, 154-170 R; and α-RST, 248-274 R. There were no significant differences in the magnitude of the shoulder or extrapolation number of the survival curves, nor in the ability of the three cell strains to accumulate and repair sublethal radiation damage. It appears unlikely that the unusual resistance of the hybrid strain is simply related to the increase in chromosome number; more likely, it involves some interaction between the two genomes. The study of somatic cell hybrids may offer further insight into the factors controlling the radiosensitivity of mammalian cells.
Protein Electrophoretic Profiles and the Origin of the B Genome of Wheat
Authors: Johnson B. Lennart
Published: May 2006

Protein electrophoretic profiles cast doubt upon the prevalent theory that the B genome of the polyploid wheats was derived from a species of
Aegilops
. They suggest, instead, that the wild tetraploid wheats comprise a complex, whose components were derived from various combinations of diploid
Triticum
types, which evidently include the B-genome type.
Third Party Mixed-Leukocyte Culture Test: A Potential New Method of Histocompatibility Testing
Authors: Park B. H. , Good R. A.
Published: May 2006

The disparity index is an expression of histocompatibility difference between two siblings with identical human leukocyte antigen (HL-A) type who are nonreactive in mixed leukocyte culture (MLC) test. This index is derived from a third-party MLC test. The disparity index was found to be correlated with the severity of graft-versus-host reaction in bone marrow transplantation between HL-A-identical siblings. The disparity index may prove to be a useful means of predicting the severity of graft-versus-host reaction and the outcome of bone marrow graft when HL-A- and MLC-matched sibling donors are studied. The third-party MLC test is offered as a new method of histocompatibility testing. It may provide a useful model for the study of immunogenetics relative to so-called weaker histocompatibility determinants in man and experimental animals.
Early Extracellular Events in Infection of Competent
Bacillus subtilis
by DNA of Bacteriophage SP82G
Authors: Williams Gordon L. , Green D. Macdonald
Published: May 2006

Analysis, by the recovery of specific genetic “markers,” of the effects of DNase I, physical shear, and temperature shock on DNA-cell complexes demonstrates that sequential attachment of both ends of bacteriophage SP82G DNA to
Bacillus subtilis
precedes entry of the DNA molecule into the cell, and that each attachment is end-and time-specific. The first attachment involves an initial reversible phase, followed by irreversible binding. After a latent period, the second end then attaches to the cell. Entry of the molecule begins immediately after binding of the second end has occurred, and entry is complete within 3 min. The polarity of entry, as judged by attainment of resistance to DNase I, is the reverse of that observed in normal phage injection.
Structures of the Visual Chromophores and Related Pigments: A Conformational Basis of Visual Excitation
Authors: Sundaralingam M. , Beddell C.
Published: May 2006

A detailed conformational analysis of the known crystal structures of vitamin A, carotenoid, and xanthenoid derivatives has been made. These studies suggest that the visual chromophore 11-
cis
retinal and its isomers may each occur in several different conformational states, which would be expected to have different lightabsorbing characteristics. The presence of such states for 11-
cis
retinal and all-
trans
retinal may contribute to the observed rhodopsin intermediates that have been characterized by different λ
max
values, and to the breadth of spectral response in scotopic and color vision.
Physical Adsorption of the Quantum Gas
Authors: Kim Un Sik , Schmidt R. , Jhon Mu Shik , Eyring Henry
Published: May 2006

The significant structure theory of quantum liquids such as hydrogen, deuterium, and helium has been applied to the physical adsorption occurring in the submonolayer region. The partition function for the two-dimensional adsorbed fluid has been derived. The properties of isothermal and isosteric heat show good agreement with the available data from the literature.
On the Theory of Ion Transport Across the Nerve Membrane, VI. Free Energy and Activation Free Energies of Conformational Change
Authors: Hill Terrell L. , Chen Yi-Der
Published: May 2006

Empirical functions, such as
n
∞
(
V
) and τ

n

(
V
) (of the Hodgkin-Huxley type), can be recast in terms of more fundamental functions
F
(
V
) (related to a conformational free energy change) and θ(
V
) (related to the corresponding free energies of activation). Examples of
F
(
V
) and θ(
V
) are given, for squid and frog node.
F
(
V
) is essentially a quadratic function of
V
. The possible molecular origin, for protein-like subunits, of the linear (e.g., net charge) and quadratic (e.g., polarizability) terms in
F
(
V
) is discussed. The
F
(
V
), θ(
V
) kind of analysis leads rather automatically to a simple explanation of the well-known approximate coincidence in location (
V
value) of the maximum in τ

n

(
V
) (time constant) and the steeply rising part of
n
∞
(
V
) (also
m
, 1 -
h
).
An RNA-DNA Complex Intermediate in Ribosomal Gene Amplification
Authors: Mahdavi Vijak , Crippa Marco
Published: May 2006

An RNA-ribosomal DNA complex can be isolated from ovaries of
Xenopus laevis
incubated
in vitro
during the amplification stage. A part of the RNA present in the complex is resistent to RNase but becomes completely sensitive after heat denaturation, a treatment that also allows the separation of the RNA from the DNA. The size of the RNA-ribosomal DNA complex is strongly reduced after treatment with RNase. A small fraction of the RNA present in the complex is complementary to the spacer region of the strand, which is not transcribed
in vivo
into cytoplasmic 18S and 28S ribosomal RNA.
Induction of a Reductive Pathway for Deoxyribonucleotide Synthesis during Early Embryogenesis of the Sea Urchin
Authors: Noronha John M. , Sheys Gerald H. , Buchanan John M.
Published: May 2006

Cell-free extracts of
Arbacia
eggs (
Arbacia punctulata
) apparently do not contain an enzymatic system for the reduction of ribonucleotides to deoxyribonucleotides. However, during an interval of 5 hr after fertilization at 23°, an enzymatic system is produced that is capable of catalyzing the reduction of CDP to dCDP in the presence of Mg
2+
, ethylenediaminetetraacetate, ATP, and a reducing agent, dithiothreitol. The activity is first seen about 1 hr after fertilization, and reaches a peak at about 5 hr. The appearance of the ribonucleotide reductase is prevented by the addition of emetine or puromycin, inhibitors of protein synthesis, to the cells before fertilization. Inclusion of actinomycin D in the cell suspension at a concentration sufficient to inhibit synthesis of messenger RNA does not appreciably affect the production of the enzyme activity. Preexisting, maternal RNA is thus used for synthesis of reductase. Ribonucleotide reductase may, therefore, represent the first example of an enzyme system absent in unfertilized eggs that is produced in response to fertilization.
The Stabilization of Episomal Integration by Genetic Inversion: A General Hypothesis
Authors: Adelberg Edward A. , Bergquist Peter
Published: May 2006

In F′ cells of
Escherichia coli
K12, recombination in the region of genetic duplication between chromosome and F-genote produces a rapid alteration between the integrated and detached states of the episome. Nevertheless, F′ strains can give rise to Hfr cells in which the F-genote has undergone stable integration. We have found that one such Hfr has retained the genetic duplication as well as the recombination proficiency of the parental F′ strain; to account for the failure of recombination to detach the episome in this Hfr, we have postulated the inversion of one of the duplicated regions. A general model is presented, showing that an inversion must prevent episome detachment by any combination of genetic crossovers.