bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosomal localization of human genes governing the interferon-induced antiviral state.
Authors: Chany C , Vignal M , Couillin P , Van Cong N , Boué J , Boué A
Published: May 2006

Interferon sensitivity of different normal and aneusomic human cells and of different mouse-human hybrids cells has been compared. G21 trisomic cells are more sensitive than diploid cells; whereas, on the contrary, triploid cells are normal in their human interferon sensitivity. Among other aneusomic cell lines tested, E16 trisomic cells are significantly less sensitive. These data are in favor of the hypotheses that the G21 chromosome carries genetic information for structural proteins involved in the receptor system for interferon, that there is a regulatory mechanism governing the antiviral state, and that the E16 chromosome is a possible candidate for carrying information for such a depressive regulatory mechanism. None of the chromosome abnormalities studies are involved with interferon synthesis.
The characters of the holomorphic discrete series
Authors: Martens Susan
Published: May 2006

This paper summarizes the derivation of an explicit and global formula for the character of any holomorphic discrete series representation of a reductive Lie group
G
which satisfies certain conditions. The only very restrictive condition is that
G/K
be a Hermitian symmetric space. (Here
K
is the maximal compact subgroup of
G
.)
Some fundamental groups in the arithmetic of algebraic curves over finite fields
Authors: Ihara Yasutaka
Published: May 2006

Associated with some systems of unramified coverings of algebraic curves over finite fields there are spaces analogous to the universal covering transformation spaces. These spaces have also arithmetic features; they represent all the Frobeniuses in the systems. This theory can be applied to the reduction mod [unk] of the Shimura curves.
Necessary and sufficient conditions for solvability of the Lewy equation
Authors: Greiner P. C. , Kohn J. J. , Stein E. M.
Published: May 2006

We find the necessary and sufficient conditions for the local solvability of Lewy's equation, ([unk]/[unk]
z
+
īz
[unk]/[unk]
t
)
u
=
f
. If R
3
is realized as the boundary of the generalized “upper-half-space” in C
2
, then the conditions are, near a point
P
[unk] R
3
, the analytic continuability of the Cauchy-Szegö integral of
f
past
P
. In case the sufficient condition is satisfied, solutions are found that satisfy optimal regularity properties. Various generalizations are also given.
Relationship between A-type and C-type particles in cells infected by Rous sarcoma virus.
Authors: de Giuli C , Hanafusa H , Kawai S , Dales S , Chen J H , Hsu K C
Published: May 2006

Chicken cells infected with avian RNA tumor virus often contain small cytoplasmic A-type particles which commonly exist as clusters of 50--100 particles when viewed in thin sections. These particles were found more consistently in Rous sarcoma virus-infected than Rous-associated virus-infected cultures, but were generally present in only a small fraction of the total infected cells. The results of the survey of cells infected with various strains of leukosis-sarcoma viruses led to the hypothesis that the A particles develop in cells undergoing cytopathological degeneration. The hypothesis explains also the evanescent nature of the appearance of these particles in infected cells. The application of immunoelectron microscopic methods using monospecific antisera against viral internal proteins revealed that the A particles contain components immunologically related to the proteins of C-type virus.
Analysis of oncornavirus RNA subunits by electron microscopy.
Authors: Heine U I , Weber G H , Cottler-Fox M , Layard M W , Stephenson M L , Zamecnik P C
Published: May 2006

Subunits of oncornavirus (avian myeloblastosis virus) RNA were isolated from purified 60--70S viral RNA by heat dissociation. Molecules sedimenting at 35 S, assumed to be the major component of the viral genome, were visualized in the electron microscope and their lengths were statistically analyzed. The results indicate a rather heterogeneous population of molecules with five distinct, reproducible size groups, an observation that excludes the assumption of random degradation of the genome. In addition, molecules of 28 and 18S RNA, always present in oncornavirus RNA preparations, were examined with the same methods. Some of these molecules possess secondary-structure regions similar to those characteristic for ribosomal RNA.
Titration of sodium channels in canine gastric mucosa.
Authors: Kauffman G L , Thompson M R
Published: May 2006

Net Na+ flux from mucosa to lumen, potential difference, and volume and plasma protein outputs were measured in vagally denervated, separated pouches of the dog's oxyntic or pyloric glandular mucosa when the pouches were irrigated with Na+-free solutions whose pH ranged from 1.5 to 12.2. The apparent permeability to Na+(P'Na) was calculated. P'Na is lowest when the mucosa is bathed with acid and increases 2- to 3-fold when the pH is raised to 10. In the range of pH 10.0--11.2 P'Na is greater by an order of magnitude, but volume output is small, and no plasma proteins are shed. When the pH is above 11.2 there is an abrupt increase in P'Na, and the mucosa sheds a large volume of fluid containing plasma proteins. The change effected by raising the pH to the range of 10.0--11.2 occurs within 10 sec, and it is reversible. The change effected by raising the pH above 11.2 also occurs within 10 sec, and it is partly reversible.
Model of solute and water movement in the kidney.
Authors: Stephenson J L , Mejia R , Tewarson R P
Published: May 2006

Finite difference equations describing salt and water movement in a model of the mammalian kidney have been solved numerically by an extension of the Newton-Raphson method used for the medullary counterflow system. The method permits both steady-state and transient solutions. It has been possible to simulate behavior of the whole kidney as a function of hydrostatic pressures in renal artery, vein, and pelvis; protein and other solute concentrations in arterial blood; and phenomenological equations describing transport of solute and water across nephron and capillary walls. With the model it has been possible to compute concentrations, flows, and hydrostatic pressures in the various nephron segments and in cortical and medullary capillaries and interstitium. In a general way, calculations on the model have met intuitive expectations. In addition, they have reemphasized the critical dependence of renal function on the hydraulic and solute permeabilities of glomerular, postglomerular, and medullary capillaries. These studies provide additional support for our thesis that the functional unit of the kidney is not the single nephron, but a nephrovascular unit consisting of a group of nephrons and their tightly coupled vasculature.
Dynamic properties of isolated acetylcholine receptor proteins: release of calcium ions caused by acetylcholine binding.
Authors: Chang H W , Neumann E
Published: May 2006

Interaction of Ca and acetylcholine (AcCh) ions with purified acetylcholine receptor (AcChR) from Torpedo californica and Electrophorus electricus has been investigated in view of these ions' role proposed in bioelectricity. Spectrophotometric Ca titration using murexide as an indicator and an ultrafiltration method with 45Ca show that AcChR proteins have a high binding capacity for Ca ions. Per macromolecule of 260,000 daltons, up to 60 Ca ions can be bound with at least three Ca dissociation constants. A linear inhibition of AcCh binding to AcChR by Ca was observed in the 0.1-1 mM Ca range, indicating competition of AcCh and Ca for AcChR. The addition of AcCh to a Ca-AcChR solution at 1.2 mM Ca causes release of four to six bound Ca ions from AcChR when a maximum of two AcCh ions are bound per 260,000 dalton macromolecule. The subsequent addition of alpha-bungarotoxin causes reuptake of up to six Ca ions by AcChR. These results suggest that the neural activator AcCh and the inhibitor alpha-bungarotoxin induce opposing shifts between different conformational states of isolated AcChR.
Studies on the recovery of crown gall tumor cells
Authors: Turgeon Robert , Wood Henry N. , Braun Armin C.
Published: May 2006

Our previous studies have shown that, while a persistent but potentially reversible suppression of the tumorous state appears to be a characteristic feature of the vegetative phase of teratoma shoot growth in the crown gall disease of plants, a recovery from that state occurs during the reproductive phase. An analysis has now been made of the reproductive process in an attempt to define the precise stage at which recovery occurs. The results of this analysis have shown that diploid somatic cells of teratoma-derived flower parts such as those found in petals and filaments are inherently neoplastic. On the other hand, haploid cells of plants grown from anthers of the same flowers and diploid cells of F
1
generation plants grown from teratoma-derived seed have, by generally accepted criteria, recovered from the tumorous state. These findings have been interpreted to mean that the loss of neoplastic properties occurs in crown gall teratoma cells during meiosis rather than during fertilization or later stages of the reproductive process.

An analysis of more than 2000 teratoma-derived tumor shoots has shown, moreover, that a recovery from the tumorous state may also occur, although apparently as a very rare event, during the vegetative phase of teratoma shoot growth.
Deep inelastic scattering of charged leptons
Authors: Schwinger Julian
Published: May 2006

The concept of a model based on the hypothesis of smooth extrapolation rather than explicit dynamical speculation is expounded. The existing body of successful applications is extended to the longitudinal cross section in deep inelastic scattering, and predictions are made for the asymmetry in scattering of polarized electrons on polarized protons.
Viroids are single-stranded covalently closed circular RNA molecules existing as highly base-paired rod-like structures.
Authors: Sanger H L , Klotz G , Riesner D , Gross H J , Kleinschmidt A K
Published: May 2006

Viroids are uncoated infectious RNA molecules pathogenic to certain higher plants. Four different highly purified viroids were studied. By ultracentrifugation, thermal denaturation, electron microscopy, and end group analysis the following features were established: (i) the molecular weight of cucumber pale fruit viroid from tomato is 110,000, of citrus exocortis viroid from Gynura 119,000, of citrus exocortis viroid from tomato 119,000 and of potato spindle tuber viroid from tomato 127,000. (ii) Viroids are single-stranded molecules. (iii) Virods exhibit high thermal stability, cooperativity, and self-complementarity resulting in a rod-like native structure. (iv) Viroids are covalently closed circular RNA molecules.
Hydrolysis and transpeptidation of peptide substrates by acetyl-pepsin.
Authors: Richman P G , Fruton J S
Published: May 2006

Treatment of swine pepsin with acetylimidazole to acetylate approximately five of its 16 tyrosyl residues causes a significant enhancement of catalytic efficiency (kcat/Km) toward substrates such as dansyl-glycyl-glycyl-L-phenylalanyl-L-phenylalanine 3-(4-pyridyl)propyl ester and benzyloxy-carbonyl-(glycyl)n-p-nitroLphenylalnyl-Lphenylalanyl-L-tyrosine (where n = 0, 1,2). Stopped-flow kinetic studies, under conditions of enzyme excess, with the dansyl peptide have shown that, as with untreated pepsin, the rate-limiting step in the over-all catalytic process is associated with the decomposition of the first detectable enzyme-substrate complex, whose dissociation constant is approximately equal to the Km found in steady-state kinetic experiments. With substrates of the type benzoyl-(glycyl)n-nitro-L-phenylalanyl-L-tyrosine, an increase in the chain length of the peptide leads to an increase in the value of kcat/Km, supporting the view that secondary enzyme-substrate interactions may produce at the extended active site conformational changes that are reflected in higher catalytic efficiency. This effect is more marked with acetyl-pepsin than with untreated pepsin, and suggests that the conformational mobility of the active site is increased by partial acetylation. Acetyl-pepsin is less effective than untreated pepsin in catalyzing transpeptidation reactions in which acetyl-L-phenylalanyl-L-tyrosine and benzyloxycarbonyl-(glycyl)n-p-nitro-L-phenylalanine are the reactants; this finding is consistent with the more rapid hydrolysis of the product of transpeptidation.
Mapping oligonucleotides of Rous sarcoma virus RNA that segregate with polymerase and group-specific antigen markers in recombinants.
Authors: Wang L , Galehouse D , Mellon P , Duesberg P , Mason W S , Vogt P K
Published: May 2006

The RNase-T1-resistant oligonucleotides of two Prague Rous sarcoma viruses with temperature-sensitive (ts) DNA polymerases (DNA nucleotidyltransferases), termed ts LA 337 and 335 of one leukosis virus, RAV-6, and 20 of their recombinant progeny have been mapped relative to the 3' poly (A) terminus of the viral RNA. The resulting oligonucleotide maps have been ocrrelated with markers of the four known viral genetic elements encoded in the RNA of 10,000 nucleotides. In accord with previous results recombinant RNAs contained (i) oligonucleotides characteristic of the src gene, coding for sarcoma formation, between the poly(A) end and 2000 nucleotides and (ii) olignucleotides characteristic of the env gene, coding for the envelope glycoprotein, between 2500 and 5000 nucleo tides from the poly(A) end. (iii) A cluster of four oligonucleotides that mapped between 6000 and 8000 nucleotides from the 3' poly(A) end of each RNA was shared by both parental viruses and all recombinants. Since all other map segments of our recombinants failed to segregate with the ts- or wild-type markers of the parental DNA polymerase gene (pol), it was concluded that the ts pol lesion maps in this RNA segment. (iv) The 5' segment of each recombinant RNA contained a cluster of four to five oligonucleotides whose parental origin correlated with an electrophoretic marker of one of the parental virion proteins, p27, a major product of the viral gag gene. The gene order 5'-gag-pol-env-src-poly(A) is consistent with our data.
Expression of the thymidylate synthetase gene of the Bacillus subtilis bacteriophage Phi-3-T in Escherichia coli.
Authors: Ehrlich S D , Bursztyn-Pettegrew H , Stroynowski I , Lederberg J
Published: May 2006

The thymidylate synthetase gene of B. subtilis bacteriophage Phi-3-T, when cloned in plasmids pSC101 or pMB9 is expressed in E. coli. The promoter of the cloned gene is likely to originate in Phi-3-T. Rearrangements of hybrid plasmid sequences during the cloning have been noted. B. subtilis strains can be transformed with hybrid DNAs. The transformants contain sequences of Phi-3-T, but not those of plasmid vectors.
Allelic heterogeneity within allozymes separated by electrophoresis in Drosophila pseudoobscura.
Authors: McDowell R E , Prakash S
Published: May 2006

Electrophoretic separation of esterase-5 allozymes of Drosophila pseudoobscura in gels of different acrylamide concentrations and in different buffer systems has revealed the existence of six different alleles within the most frequent class, esterase-5(1.00), and three alleles in the other most frequent class, esterase-5(1.07). Two of the alleles affect subunit binding. Esterase-5 allozyme classes based on electrophoresis in 5% acrylamide gels are therefore highly heterogeneous.
Heat mutagenesis in bacteriophage T4: the transversion pathway.
Authors: Bingham P M , Baltz R H , Ripley L S , Drake J W
Published: May 2006

Heat induces transversions (as well as transitions) at G-C base pairs in bacteriophage T4. The target base for transversions is guanine,which is converted to a product which is sometimes replicated and transcribed as a pyrimidine.A model for this process is proposed in which the deoxyguanosine glycosidic bond migrates from N9 to N2: the resulting deoxyneoguanosine may pair with normal guanine to produce G-C leads to C-G transversions.
Ear and hearing in Sphenodon punctatus.
Authors: Gans C , Wever E G
Published: May 2006

Observations on Sphenodon punctatus have revealed new features of the anatomy of the ear,and measurements in a living specimen by means of cochlear potentials show the form and level of this ear's performance in sound reception. For an animal lacking an external ear opening and a functional tympanic membrane, the sensitivity of from 100-900 Hz is surprisingly good in low tones with peak response around 200-400 Hz. The inner ear is well developed, with a tectorial membrane connected to a tectorial plate that extends throughout the cochlea. The best region of sensitivity agrees well with the main frequency components of the animal's vocalizations.
DNA unwinding component of the nonhistone chromatin proteins.
Authors: Thomas T L , Patel G L
Published: May 2006

A subclass of nonhistone chromatin proteins from rat liver, previously shown to exhibit high affinity for DNA, has been fractionated by single-stranded DNA-agarose affinity chromatography. The protein fraction that bound to DNA-agarose in 0.19 M NaCl-buffer and was eluted with 2 M NaCl-buffer is enriched for a protein component of approximately 20,000 daltons and exhibits preferential binding to denatured DNA. This nonhistone protein fraction specific for single strands binds to DNA in a non-species-specific manner, and causes helix-coil transition of synthetic poly[d(A-T)-d(A-T)] at 25 degrees, as indicated by the increase in absorbance of ultraviolet light at 260 nm. The observed hyperchromicity does not result from any nuclease activity in the protein fraction, because addition of Mg+2 results in partial hypochromic shift, and the protein/DNA complex is retained by nitrocellulose filters.
Physical-chemical approach to the transient change in Na ion conductivity of excitable membranes
Authors: Rawlings Philip K. , Neumann Eberhard
Published: May 2006

A new method is proposed for analyzing the rapid transient current component (Na ions) in voltage clamp experiments on excitable membranes. The method is based on only two very general assumptions: the Na ion conductivity of an excitable membrane is determined by some general membrane parameter, the kinetic behavior of which is consistently described by the sum of only two simple exponential terms. A least square computer analysis for the data by L. Goldman and C. L. Schauf on
Myxicola
axons is described [(1973)
J. Gen. Physiol.
61, 361-384]. The method gives (as a result) the relationship between conductivity and membrane parameter. A physically plausible, chemical model (cycle of three states) is proposed for a dissipative control of the Na ion conductivity. The rate constants for the specific model are calculated from kinetic parameters derived only from the general analysis. These rate constants reproduce the original voltage clamp data in
every
feature which includes peak current ratios (h
∞
)-shift with test potential. By allowing for differences in the experimental conditions, we derive essentially the same rate constants for the voltage clamp data of A. L. Hodgkin and A. F. Huxley on squid giant axons.
Genetic analysis of a transposable suppressor gene in Saccharomyces cerevisiae.
Authors: Laten H M , Gorman J , Webb F , Bock R M
Published: May 2006

We have demonstrated in Saccharomyces cerevisiae the transposition of a gene coding for an efficient ochre (UAA) suppressor from a centromere-linked site on chromosome III to two new sites in the yeast genome. One site is on chromosome VI, very close to, if not allelic with, SUP11, one of eight genes coding for a tyrosine-inserting suppressor. The second site is on chromosome III, unlinked to the centromere and distal to the mating type locus. This site is very close to those mapped for the recessive lethal amber suppressors, SUP-RL1 and SUP61.
Do highly oncogenic group A human adenoviruses cause human cancer? Analysis of human tumors for adenovirus 12 transforming DNA sequences.
Authors: Mackey J K , Rigden P M , Green M
Published: May 2006

Adenovirus 12 (Ad12) (Huie) (highly oncogenic group A) readily induces tumors in newborn rodents. Since Ad12 is isolated from human fecal samples, we investigated whether it plays a role in the etiology of human gastrointestinal cancer. If Ad12 is a causal agent of human cancer, then human tumors should contain Ad12 transforming genes, as indicated by studies of cells transformed in vitro and in vivo by oncogenic viruses. Ad12 DNA and the Ad12 transforming restriction fragment (EcoRI-C fragment, left 16% of the viral genome) were labeled in vitro to 10(7) to 4 X 10(8) cpm/mug by the nick translation reaction of DNA polymerase of Escherichia coli. The fidelity and sensitivity of these probes were established by (i) analysis of DNA from Ad12-transformed cells and from hamsters with tumors induced by Ad12, (ii) reconstruction experiments with added Ad12 DNA and EcoRI restriction fragments, and (iii) comparison of annealing characteristics with Ad12 probes labeled in vivo. With Ad12 [3H]DNA as probe, no viral DNA sequences were detected in 18 normal gastrointestinal tissues and 34 gastrointestinal tumors, including cancers of the colon, rectum, small intestine, and stomach, under conditions that would detect 0.1 copy of the Ad12 genome per tumor cell. Similar analyses of Ad12-transformed hamster cells and Ad12 primary hamster tumors indicated 6-18 copies per cell of over 90% of the viral genome. With the Ad12 EcoRI-C transforming fragment as probe, no hybridization was detected with 32 human gastrointestinal tumors and five normal tissues; this result excludes 1-2% of the Ad12 genome per tumor cell. Our date are strong evidence that Ad12 is not a major cause of human gastrointestinal cancer. The Ad12 transforming EcoRI-C fragment hybridized (50-68% efficiency) with other Ad12 isolates and with Ad18 and 31 (members of oncogenic group A), but not at all with 28 other human Ad serotypes (manuscript in preparation). Thus other group A members probably are also not involved in human gastrointestinal cancer. No viral DNA sequences were detected in 12 normal lungs and 22 lung tumors, suggesting that respiratory cancer does not involve an Ad12 etiology.
Force-velocity characteristics for calcium-activated mammalian slow-twitch and fast-twitch skeletal fibers from the guinea pig.
Authors: Gulati J
Published: May 2006

Twitch fiber bundles from a slow (soleus) and a fast (extensor digitorum longus) mammalian muscle after mild chemical treatment were activated with calcium and relaxed in calcium-free solution. Like the electrically activated whole muscles, the force-velocity relationship was such that, at each relative load, the steady speed of shortening for the fast fibers was about two times greater than that for the slow twitch fibers. The duration of pre-steady motion in the two types of fibers was the same. The data provide direct evidence that the difference in the shortening characteristics of the two types of fibers is due to differences in their cross-bridge properties.
Chromatin-like organization of the adenovirus chromosome.
Authors: Corden J , Engelking H M , Pearson G D
Published: May 2006

Staphylococcal nuclease (nucleate 3'-oligonucleotidohydrolase; EC 3.1.4.7) cleaved DNA within disrupted adenovirus particles into a regular series of fragments with a repeat unit of 200 base pairs. Since this pattern did not eppear when DNA alone was digested, we postulate that the orderly arrangement of core polypeptides protects discrete regions of DNA from nuclease attack. The 23 X 10(6) dalton adenovirus DNA molecule can accommodate 180 units of roughly 200 base pairs. Based on the stoichiometry of core polypeptides, we calculate that each repeat unit contains six copies of polypeptide VII and a single copy of polypeptide V. This model is bases on proposals for the structure of eukaryotic chromatin. Very brief nuclease digestion generated 1800 base pair fragments (1/20 of the adenovirus chromosome). This result is discussed in terms of a higher order folding of viral DNA within the virus particle.
Regulation of expression of Adh genes in maize.
Authors: Schwartz D
Published: May 2006

A regulatory mutant of the Adh (alcohol dehydrogenase) gene was induced by ethyl methanesulfonate. The mutation reduces the ability of the gene to complete for the limited gene activating factor. The mutant shows full activity in the homozygote but only one-half the activity of the progenitor gene in heterozygotes where it is competing with another allele for the limited factor. Evidence is presented for multiple regulatory sites in both the Adh and Adh2 loci.
Blood-aqueous barrier can be circumvented by lowering intraocular pressure.
Authors: Raviola G
Published: May 2006

Rhesus monkeys were injected intravenously with hypertonic urea (9 ml/kg body weight of 30% urea in 10% invert sugar) and the intraocular pressure was measured with an applamatic tonometer. When this pressure reached its minimum (20% of the normal value) horseradish peroxidase (molecular weight 40,000; radius of an equivalent hydrodynamic sphere about 2.5 nm; 0.5 g/kg body weight), was injected intravenously. Twenty minutes following peroxidase administration, either aqueous humor was sampled from the anterior chamber for biochemical determination of peroxidase activity, or one eyeball was enucleated and processed for light and electron microscopic localization of the enzymatic tracer. This experiment showed that: (1) therapeutic doses of hypertonic urea do not cause a breakdown of either the blood-retina or the blood-aqueous barriers; (2) as intraocular pressure decreases, peroxidase-containing blood flows back from the episcleral veins into the Schlemm canal; (3) macromolecules up to the dimensions of horseradish peroxidase leak through the intercellular clefts of the endothelium of the Schlemm canal, permeate the juxtacanalicular connective tissue and trabecular meshwork, and finally enter the anterior chamber. Thus, blood-borne substances can circumvent the blood-aqueous barrier when intraocular pressure is decreased, and administration of a hypertonic agent may represent a simple pharmacological device to cause penetration into the ocular chambers by drugs that are normally excluded from the interior of the eye.
Genetic recombination of bacteriophage T7 DNA in vitro.
Authors: Sadowski P D , Vetter D
Published: May 2006

We have demonstrated recombination of bacteriophage T7 DNA in vitro. An extract of Escherichia coli B cells infected with wild-type T7(T7+) is incubated with mature DNA extracted from T7 phage. Packaging of the exogenous DNA within the phage head appears to be preceded by recombination of exogenously added DNA with DNA present in the extracts. In order to detect the recombination, we used an exogenous DNA bearing a marker (ss-) such that progeny phage which have packaged this marker are able to plate on Shigella sonnei D2 571-48, whereas T7+ phage present in the extracts do not. The recombinational process bears many of the characteristics of in vivo recombination. The exogenous DNA is not packaged intact but undergoes fragmentation to a length of about 3000 base pairs before being incorporated into a mature DNA molecule. If ss- DNA bearing an amber mutation is used in the assay, the frequency of amber+ progeny produced varies with the distance of the amber marker from the ss- marker. When DNA bearing three mutations is used in the reaction, phage heterozygous for the unselected marker are readily detected. Finally the products of phage genes 4 (DNA replication protein), 5(DNA polymerase), and 6(exonuclease), genes previously implicated in recombination in vivo, are required for the in vitro reaction.
A new group of potent inducers of differentiation in murine erythroleukemia cells.
Authors: Reuben R C , Wife R L , Breslow R , Rifkind R A , Marks P A
Published: May 2006

This report identifies a group of compounds, polymethylene bisacetamides (acetylated diamines), which are potent inducers of erythroid differentiation in murine erythroleukemia cells. A known inducing agent, N-methylacetamide, was dimerized through varying numbers of methylenes in an attempt to increase the local effective concentration at adjacent target sites. The simple dimer was no more effective than N-methylacetamide alone; introduction of five to eight methylenes between acetamide groups substantially increased the effectiveness of these compounds. The hexamethylene bisacetamide was active between 0.5 mM and 5 mM; the percentage of cells induced and the rate at which they were recruited to differentiation was dependent upon the concentration of inducer within this range. At 5 mM hexamethylene bisacetamide essentially the entire population (greater than 99%) was induced to a pathway of erythroid differentiation which was greater differentiation of the cultured cells than with any inducer yet tested.
Significance of constitutive integrase synthesis.
Authors: Campbell A
Published: May 2006

One conceivable function for constitutive integrase formation by lambda prophage is to stabilize the inserted state by catalyzing reinsertion of prophages that are accidentally excised. As this hypothesis implies a dynamic equilibrium betwen inserted and noninserted DNA, the existence of such an equilibrium is explored. By examining the frequency with which prophages appear in an initially unoccupied chromosomal site of a lysogenic bacterium in which the prophage attachment site is duplicated, the off-rate is estimated as less than 10(-2) per generation for wild-type lambda, and less than 4 x 10(-4) for N- mutants of lambda. From the rate of integrase-catalyzed haploidization of certain partial diploid strains, the rate of spontaneous integrase activity is estimated as 3 x 10(-3) per generation. From these values I conclude that constitutive integrase will not appreciably stabilize the inserted state by virtue of its known activity.
Peroxidase complex with concomitant anodal and cathodal variation in red-fruited tomato species
Authors: Rick Charles M. , Fobes Jon F.
Published: May 2006

Four groups of bands (a-d) are controlled by 19 alleles of the Peroxidase-4 (
Prx-4
) complex in the red-fruited tomato species,
Lycopersicon esculentum
and
L. pimpinellifolium
. Heterozygotes can be detected by virtue of codominance in all combinations except a few in which bands of single groups are absent (“semi-null” alleles). No recombinations were detected in 7419 F
2
segregants of 53 different combinations of alleles. A maximum fiducial limit (
P
= 0.01) of 0.08% crossing-over between any
Prx-4
band groups is estimated. Variation of the anodal b bands is absolutely associated with that of the cathodal d band in respect to presence versus absence and direction of migration. In respect to the origin of these variants, the probability of 18 instances of simultaneous mutation of genes at two loci, always in such complete agreement, is so remote that no more than one locus could conceivably govern b and d. The disposition of a is not similarly associated with that of the other bands, while that of the faint-staining c could not always be reliably resolved. The negation of all save extremely low recombination rates and the observed concomitant variation of b and d strongly support the concept of single locus control of all
Prx-4
banding, this hypothesis being espoused until rejection should be required be required by future research. Models of single locus control of several isozymes are discussed.
Prevention and suppression by azathioprine of venom-induced protein-losing gastropathy in dogs.
Authors: Davenport H W
Published: May 2006

Irrigation of the dog's oxyntic glandular mucosa contained in a chronically prepared, vagally denervated, separated pouch of the dog's stomach with a solution (0.5 mg ml-1) of lyophilized venom of the hooded cobra (Naja naja) increases the permeability of the mucosa. If irrigation with venom solution is repeated at weekly intervals, the mucosa responds with increasing plasma-shedding which reaches a peak of 1-2 ml min-1 from roughly 60 cm2 of mucosa in 4-6 weeks. Plasma shedding in response to irrigation with venom gradually declines, leaving a permanent residual response of different magnitude in different dogs. Giving naive dogs the immunosuppressant azathioprine by mouth in a dose of 5 mg kg-1 day-1, beginning 1 week before the first irrigation with venom solution and continuing for 4 weeks, postpones the plasma-shedding response until the sixth or seventh week of venom irrigation. The plasma-shedding response is wholly or partially suppressed by further administration of azathioprine by mouth in a dose of 3.3 mg kg-1 day-1. These data support the hypothesis that the plasma-shedding response to repeated venom irrigation involves the immune system of the stomach.
Functional incorporation of ganglioside into intact cells: induction of choleragen responsiveness.
Authors: Moss J , Fishman P H , Manganiello V C , Vaughan M , Brady R O
Published: May 2006

NCTC 2071 cells are unable to synthesize the monosialoganglioside GM1. When grown in chemically defined medium these cells contained no detectable GM1 and did not accumulate 3': 5'-cyclic AMP in response to choleragen. Incubation of the cells with [3H]GM1 permitted quantification of ganglioside uptake which was dependent on time and concentration of [3H]GM1 in the medium. Responsiveness to choleragen was demonstrated with binding of as few as 17,000 molecules of [3H]GM1 per cell; a maximal response was observed with 10(5) molecules per cell. With increasing cellular content of GM1, the rate of rise in intracellular cyclic AMP in response to choleragen was increased. With greater than 1 X 10(5) molecules of GM1 per cell, the delay between addition of choleragen and the cyclic AMP response was inversely proportional to choleragen concentration; less than 250 molecules of choleragen per cell caused a significant increase in cyclic AMP after 8 hr of incubation. Although the responsiveness of intact cells to choleragen was dependent on GM1, choleragen activation of adenylate cyclase in homogenates with 0.6 mM NAD was independent of added ganglioside. These observations are consistent with the view that exogenous ganglioside GM1 can be functionally integrated into the surface membrane of intact cells and serve as the choleragen receptor. Furthermore, although exogenous GM1 is required for choleragen responsiveness in intact cells, the ganglioside does not play an obligatory role in cell homogenates, where the surface receptor can presumably be bypassed.
New protein in human blood plasma, rich in proline, with lipid-binding properties.
Authors: Sata T , Havel R J , Kotite L , Kane J P
Published: May 2006

A protein that binds to a lecithin-stabilized triglyceride emulsion has been separated from plasma after removal of major lipoprotein classes by ultracentrifugation at density 1.21 g/ml. This protein, rich in proline, has been purified to electrophoretic and immunochemical homogeneity by subsequent gel and ion-exchange chromatography. In native plasma and after purification, it exists as a large particle exceeding 10(6) daltons, but a single component with a molecular weight of about 74,000 is found upon polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Although the purified protein contains very little bound lipid and is not present in the major lipoprotein classes from post-absorptive individuals, it is present in chylomicrons. Its concentration in plasma varies from 12 to 41 mg/dl and is significantly correlated with that of cholesterol in lipoproteins of very low and low density but not in those of high denisty.
Construction and propagation of a defective simian virus 40 genome bearing an operator from bacteriophage lambda.
Authors: Nussbaum A L , Davoli D , Ganem D , Fareed G C
Published: May 2006

A 2400 base pair DNA segment containing the leftward operator (OL) of phage lambda was covalently joined in vitro to a fragment of simian virus 40 (SV40) DNA harboring the SV40 replication origin. The recombinant molecule was propagated in the presence of helper wild-type SV40 DNA in monkey kidney cells and partially cloned by an infectious center procedure. After propagation in monkey cells and purification, the hybrid DNA could be distinguished from wild-type SV40 DNA by its shortened length (about 80% that of SV40), specific hybridization to denatured lambda DNA immobilized on filters, specific affinity for lambda repressor, and preservation of a large part (about 2300 base pairs) of the lambda immunity region as determined by restriction nuclease cleavage patterns and electron microscopic heteroduplex analysis. These results indicate that defective SV40 replicons can serve as vectors for propagating foreign DNA in mammalian cells.
Equilibrium and stability code for a diffuse plasma
Authors: Betancourt Octavio , Garabedian Paul
Published: May 2006

A computer code to investigate the equilibrium and stability of a diffuse plasma in three dimensions is described that generalizes earlier work on a sharp free boundary model. Toroidal equilibria of a plasma are determined by considering paths of steepest descent associated with a new version of the variational principle of magnetohydrodynamics that involves mapping a fixed coordinate domain onto the plasma. A discrete approximation of the potential energy is written down following the finite element method, and the resulting expression is minimized with respect to the values of the mapping at points of a rectangular grid. If a relative minimum of the discrete analogue of the energy is attained, the corresponding equilibrium is considered to be stable.
Biological consequences of incorporation of 5-fluorocytidine in the RNA of 5-fluorouracil-treated eukaryotic cells.
Authors: Gleason M K , Fraenkel-Conrat H
Published: May 2006

Treatment of HeLa cells with 5-fluoro-[3H]uracil leads to the incorporation into cellular RNA of 5-fluorocytidine to the extent of about 0.2% of the 5-fluorouridine incorporated. In tobacco mosaic virus RNA produced in tobacco leaves this ratio is one order of magnitude lower. Copolymers of cytidylic with 5-fluorocytidylic acids show unchanged template activity with E. coli RNA polymerase, but slightly altered messenger activity in the wheat germ system, compared to poly(C), and it is suggested that some of the biological consequences of 5-fluorouracil treatment of living cells and organisms may be attributed to this mechanism.
Long-chain neutral glycolipids and gangliosides of murine fibroblast lines and their low- and high-tumourigenic hybrids.
Authors: Itaya K , Hakomori S I , Klein G
Published: May 2006

The patterns of long-chain neutral glycolipids and gangliosides of established, L-cell-derived murine fibroblast lines and their low- and high-tumorigenic hybrids were studied.
Alpha-methyl ornithine, a potent competitive inhibitor of ornithine decarboxylase, blocks proliferation of rat hepatoma cells in culture.
Authors: Mamont P S , Böhlen P , McCann P P , Bey P , Schuber F , Tardif C
Published: May 2006

A biphasic increase of putrescine concentration occurs in rat hepatoma tissue culture cells induced to proliferate. DL-alpha-Methyl ornithine, a competitive inhibitor of ornithine decarboxylase ( L-ornithine carboxylyase, EC 4.1.1.7) of hepatoma tissue culture cells, blocks the usual increases of putrescine and spermidine concentrations in these cells, and causes a rapid fall in the levels of putrescine which is followed by a striking decrease of spermidine.In parallel with the depletion of these amines, incorporation of [3H]thymidine into DNA and cell proliferation are inhibited. Addition of putrescine, spermidine, or spermine results in an immediate resumption of cell proliferation. Cell proliferation is also restored by L-ornithine presumably due to in situ competitive inhibition of ornithine decarboxylase. These findings of hepatoma tissue culture cells support the concept that polyamines play an essential function in the cell division processes.
Hypersensitivity to tobacco antigen.
Authors: Becker C G , Dubin T , Wiedemann H P
Published: May 2006

A glycoprotein of molecular weight 18,000 was purified from saline extracts of cured tobacco leaves by ammonium sulfate fractionation, chromatography on Sephadex G-25 and continuous-flow preparative electrophoresis on polyacrylamide gel. Twelve of 31 volunteers (6/15 smokers and 6/16 nonsmokers) exhibited immediate cutaneous hypersensitivity (wheal and flare reactions) when injected intracutaneously with 2 mug of this material. Immunochemically similar material was demonstrated in, and purified from, cigarette smoke condensate and cigarette smoke. The concentration in cigarette smoke condensate ("tar") was determined to be 1.8-3.6 mg/g. Antigenically crossreactive material was also demonstrated in eggplants, green peppers, potatoes, and tomatoes, which, like tobacco, are members of the family Solanaceae.
Evidence for tandem integration of avian myeloblastosis virus DNA with endogenous provirus in leukemic chicken cells.
Authors: Shoyab M , Thorley-Lawson D A , Baluda M A
Published: May 2006

The integration site of avian myeloblastosis virus (AMV) proviral DNA in DNA from leukemia chicken myeloblasts has been studied by three sequential nucleic acid hybridizations that can localize the proviral DNA according to the repetitiveness of the adjacent cellular DNA regions. First, large denatured cellular DNA fragments (2.1 x 10(6) daltons) were reassociated and fractionated according to sequence reiteration frequenct. Next, DNA remaining single-stranded in each fraction was immobilized on nitrocellulose filters hybridized with an excess of unlabeled 70S RNA from Rous-associated virus-0 to saturate the endogenous proviral DNA sequences.
Analysis of ion distribution in subcellular myocardial particulates separated by density gradient centrifugation with nonpolar liquid under ion immobilization conditions.
Authors: Visscher M B , Lee Y C
Published: May 2006

Methods have been developed for the measurement of the Ca and Mg contents of subcellular particulates, separated by nonpolar liquid density gradient ultracentrifugation. After rapid deep freezing and removal of water by freeze-drying the frozen crushed tissue, homogenization and sonification a nonpolar liquid were carried out. Application of this technique has yielded evidence that the relative amounts of Mg and Ca are greatly different in the several subcellular particulates of normal heart muscle separated by density gradient centrifugation. It also appears that the comparative specific activity of Ca, after loading the perfusates with 45Ca, is very different in the several density fractions of the normal heart. The density site of greatest loading with 45Ca is changed in Ca2+-lack arrest and is very greatly altered by the induction of paradoxical Ca contracture. The method of ion-immobilization separation for water-free particulates of different densities in nonpolar liquids appears to be applicable to analysis for various constituents of other biological materials.
Conjugate points on a limiting extremal
Authors: Morse Marston
Published: May 2006

Theorem 1
, together with the author's extensions of the Sturmian Comparison Theorems, will suffice to establish the basic Theorem 27.3, p. 211 of
Global Variational Analysis: Weierstrass Integrals on a Riemannian Manifold. Mathematical Notes
, Princeton University Press, Princeton, N.J., 1976. Here and in the preceding reference there is given a Weierstrass Integral on a compact, connected, Riemannian manifold

M
n

, conditioned as in the above reference. Let γ be an arbitrary extremal of
J
joining a point
P
to a point
Q
, ≠
P
on

M
n

. An extremal ζ of
J
joining
A
to
B
is termed
nondegenerate
if
A
and
B
are not conjugate on ζ. The
index
of ζ is by definition the “count” of conjugate points of
A
on ζ definitely preceding
B
.

THEOREM 1.
When the extremal γ is nondegenerate, extremals of J issuing from P with the same length as γ and sufficiently near γ in the sense of Fréchet, are nondegenerate and have the same index as γ
.
Isolation of a novel endogenous opiate analgesic from human blood.
Authors: Pert C B , Pert A , Tallman J F
Published: May 2006

Based upon its ability to inhibit opiate receptor binding, a low-molecular-weight substance (600) has been isolated from human plasma by extraction into butanol and ion exchange, molecular sieve, and thin-layer chromatography. When this substance, termed anodynin, is microinjected into rat periaqueductal gray matter, it causes a profound, long-lasting analgesia which is prevented by prior injection of the opiate antagonist naloxone. Anodynin (opiate receptor binding material) levels in serum from hypophysectomized rats are less than 5% of values obtained in sham-operated controls. Anodynin differs from enkephalin, a morphine-like peptide isolated from brain, in its sensitivity to enzymatic loss of opiate receptor inhibitory potency, thin-layer chromatographic mobility, and behavioral effects. Anodynin might be a hormone that acts on peripheral opiate receptors in the classical manner, but might also, due to its lipophilic nature and small size, penetrate into the brain to produce centrally mediated behavioral effects.
Spike-forming model of the neural membrane: Improvement in the parameter values
Authors: Wooldridge Dean E.
Published: May 2006

A new set of values is presented for the reaction rate and ionic conductance parameters that determine the properties of the previously developed model of the neural membrane [Wooldridge, D.E. (1975)
Proc. Natl. Acad. Sci. USA
72, 3468-3471]. The resulting improvement in the extent of the agreement between theory and experiment is briefly described.
Calcium control of actin-activated myosin adenosine triphosphatase from Dictyostelium discoideum.
Authors: Mockrin S C , Spudich J A
Published: May 2006

A protein fraction from the cellular slime mold Dictyostelium discoideum confers Ca2+-sensitivity on the activation of purified myosin adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3) from Dictyostelium by purified Dictyostelium actin. That is, the fraction inhibits the actomyosin adenosine triphosphatase activity in the absence of Ca+ but not in the presence of Ca2+. This Ca2+-sensitizing factor affects only the actin-activated myosin adenosine triphosphatase and not the enzyme activity of myosin alone. The Ca2+-sensitivity is conserved when muscle actin replaces Dictyostelium actin, but is lost when muscle myosin replaces Dictyostelium myosin. The factor appears to be a protein since it is nondialyzable, is heat labile, and can be precipitated with ammonium sulfate. The factor can be purified 70-fold on an actin-affinity column.
Polypeptides with nonsuppressible insulin-like and cell-growth promoting activities in human serum: isolation, chemical characterization, and some biological properties of forms I and II.
Authors: Rinderknecht E , Humbel R E
Published: May 2006

Serum contains a polypeptide with insulin-like activity not suppressible by insulin antibodies (NSILA). A large-scale isolation procedure for NSILA is described, starting from an acid ethanol extract of a Cohn fraction (precipitate B) obtained from human plasma. Two homogenous polypeptides with insulin-like and cell-growth promoting activities could be isolated by gel filtration, ion exchange chromatography, and preparative polyacrylamide gel electrophoresis. Both components are slightly basic polypeptides with a minimal molecular weight of 5800 +/- 400. Both are single-chain molecules with two intrachain disulfide bridges each and no free sulfhydryl groups. NSILA I and II differ, however, in their amino acid compositions. The N-terminal amino acid sequences are Gly-Pro-Glu- in NSILA I, and Ala-Tyr-Arg- and Tyr-Arg- in NSILA II. Both NSILA I and II enhance net gas exchange in adipose tissue with a specific activity 60 times lower than that of insulin. In the range of 1-50 ng/ml, both substances stimulate [3H]thymidine incorporation into DNA of chick embryo fibroblasts. The same effect can be obtained with insulin but only at concentrations 50-100 times higher than those of NSILA. These results suggest that NSILA I and II are two forms of an insulin-like hormone with predominating effects on cell and tissue growth parameters.