bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphisms in Continental and Island Populations of
Drosophila willistoni
Authors: Ayala Francisco J. , Powell Jeffrey R. , Dobzhansky Theodosius
Published: May 2006

A comparative study of genic allozyme and chromosomal polymorphisms in four continental (South American) and six oceanic island (West Indies) populations of
Drosophila willistoni
has been made. The pattern of genic polymorphism is closely similar in all populations. Although regional and local differences in gene frequencies are found, generally the same alleles occur at high, intermediate, and low frequencies in all populations. An average individual is heterozygous at 18.4 and 16.2% of its loci in the continental and island populations, respectively. By contrast, chromosomal polymorphism is sharply reduced on the islands compared to most continental populations, and some chromosomal inversions are more frequent on some islands than on others. The observations are not compatible with the hypothesis that most of the gene variants are adaptively neutral. Balancing natural selection is responsible for most of the genic polymorphism in natural populations of
D. willistoni
.
Differences between the Conformation of Arsanilazotyrosine 248 of Carboxypeptidase A in the Crystalline State and in Solution
Authors: Johansen Jack T. , Vallee Bert L.
Published: May 2006

Coupling of carboxypeptidase A crystals with diazotized arsanilic acid specifically labels tyrosine 248, an active-site residue of the enzyme. Many azophenols are yellow and their zinc complexes are red; the “yellow” absorption spectrum of zinc arsanilazocarboxypeptidase crystals is characteristic of the arsanilazotyrosyl group, not of the zinc complex. This is consistent with the interpretation of x-ray data on native crystals of carboxypeptidase A, indicating that tyrosine 248 and the zinc atom are too far apart to form a complex. However, the enzyme in solution is red, denoting the formation of a complex between zinc and arsanilazotyrosine 248. The most likely interpretation of the data is that the orientation of arsanilazotyrosine 248 in solution and in the crystal is different. If the unlabeled tyrosine 248 of native carboxypeptidase undergoes similar changes, these data may bear upon the low activity of the enzyme in the crystalline state and on the catalytic mechanism of the enzyme based on the crystal structure. The opportunities for analogous spectrochemical studies of other, similar systems are pointed out.
Arene Oxides as Intermediates in the Metabolism of Aromatic Substrates: Alkyl and Oxygen Migrations during Isomerization of Alkylated Arene Oxides
Authors: Jerina Donald M. , Kaubisch Nikolaus , Daly John W.
Published: May 2006

Phenolic products obtained on isomerization of the three arene oxides of toluene, the nine arene oxides of
ortho-, meta
-, and
para
-xylene, the arene oxide of mesitylene, and 2-methyl and 1,2-dimethylnaphthalene-1,2-oxides are compared to the phenolic products obtained by hepatic metabolism of the parent aromatic hydrocarbons. The results are compatible with the intermediacy of
certain
of these arene oxides in the metabolic pathway from hydrocarbons to phenols. Migrations of methyl groups as well as a remarkable apparent migration of oxygen are observed. The isomerization of 1,4-dimethylbenzene oxide to 2,4-dimethylphenol is analogous to the methyl migration observed in the enzymatic conversion of 4-methylphenylalanine to 3-methyltyrosine with phenylalanine hydroxylase. There are
multiple pathways of isomerization of alkylarene oxides to phenols
and they are determined by environmental and structural factors. The proportion and nature of products vary greatly with pH, which suggests the presence of different mechanisms for acid-catalyzed or spontaneous isomerizations of arene oxides.
DNA Replication and Proteins That Bind to DNA
Authors: Masker Warren E. , Eberle Helen
Published: May 2006

Cells of
Escherichia coli
15T
-
were exposed to nalidixic acid or starved for thymine to inhibit DNA synthesis while protein synthesis was allowed to continue. These treatments are known to allow subsequent DNA synthesis to continue for many hours in the absence of protein synthesis. The proteins extracted from these cells that bind to DNA were examined by DNA-cellulose chromatography and disc-gel electrophoresis. One or two species were found to be absent, or to be present in greatly reduced amounts, under these conditions.
Loci Differentially Affected by Selection in Two American Black Populations
Authors: Blumberg Baruch S. , Hesser Jana E.
Published: May 2006

The hypothesis that loci differentially affected by selection can be identified was tested by a comparison of two American black populations.

The hypothesis had previously been studied in Evans County, Georgia and the data from that study were compared with data obtained from the population of Sapelo Island, Georgia.

In both, gene frequencies for 21 polymorphic systems were determined. Estimates were made for 14 of these traits of the gene migration (
m
) from whites into these black populations, by use of the equation:
m
= (

q
n

-

q
Af

)/(

q
w

-

q
Af

), where

q
w
, q
n

, and

q
Af

are the frequencies of an allele in the white, black, and West African populations, respectively. In this calculation, it is assumed that the differences in gene frequencies between American blacks and Africans are due entirely to gene mixture. On this assumption, if only gene mixture were operating, the values of “
m
” determined for each locus would be about the same. If “
m
” has a different value at some loci than it has at others, then selection for traits controlled by genes segregating at these loci could account for this difference.

Values of “
m
” in both populations were scattered. These values were ranked for each population and the rank orders compared. There was a highly significant association between the rank order of loci in the two populations. This finding supports the hypothesis that loci differentially affected by selection can be identified, and that the selective forces have operated on the same loci in both populations.
Structure of the DNA Ligase-Adenylate Intermediate: Lysine (ε-amino)-Linked Adenosine Monophosphoramidate
Authors: Gumport Richard I. , Lehman I. R.
Published: May 2006

Proteolytic degradation of the
Escherichia coli
DNA ligase-adenylate intermediate releases adenosine 5′-monophosphate linked to the ε-amino group of lysine by a phosphoamide bond. Measurements of the rate of hydroxylaminolysis of the ligase-adenylate provide further support for a phosphoamide linkage in the native enzyme. Lysine (ε-amino)-linked adenosine monophosphoramidate has also been isolated from the T4 phage-induced ligase-adenylate intermediate. These results indicate that an initial step of the DNA ligase reaction consists of the nucleophilic attack of the ε-amino group of a lysine residue of the enzyme on the adenylyl phosphorus of DPN or ATP that leads to the formation of enzyme-bound lysine (εamino)-linked adenosine monophosphoramidate.
Lateral Diffusion of Phospholipids in a Vesicle Membrane
Authors: Kornberg Roger D. , McConnell Harden M.
Published: May 2006

Nuclear-resonance spectra of phosphatidylcholine (PC) vesicles are broadened by spin-labeled PC. The broadening of the
N
-methyl proton line is proportional to spin-labeled PC concentration; the broadening by 1 molecule in 100 of spin-labeled PC is 9.7 Hz at 35°C; the broadening is not due to collisions between vesicles, exchange of spin label between vesicles, or fusion of vesicles. These findings are proof of rapid diffusion in the plane of the PC bilayer (lateral diffusion). A further study of the broadening reveals the molecular frequency of the translation step for lateral diffusion to be much greater than 3 × 10
3
sec
-1
at 0°C.
Cytokinins: Development of a Potent Antagonist
Authors: Hecht Sidney M. , Bock Robert M. , Schmitz Ruth Y. , Skoog Folke , Leonard Nelson J.
Published: May 2006

A systematic search has resulted in the synthesis of a class of cytokinin antimetabolites. The development and biological properties of the anticytokinins are discussed in terms of one member of the class, 3- methyl - 7 - (3 - methylbutylamino)pyrazolo[4,3 -
d
]- pyrimidine.
Amino Acid Sequence of the Light Chain from a Mouse Myeloma Protein with Anti-Hapten Activity: Evidence for a Third Type of Light Chain
Authors: Schulenburg Elizabeth P. , Simms Ernest S. , Lynch Richard G. , Bradshaw Ralph A. , Eisen Herman N.
Published: May 2006

A tentative amino acid sequence has been determined for the light chain of a mouse A-myeloma (MOPC-315) protein with anti-2,4-dinitrophenyl activity. An unusual amino acid sequence in the carboxyl-terminal 104 residues suggests that the chain represents a new class of immunoglobulin light chain. The “variable” segment of this chain (amino-terminal 110 residues) differs at only eight positions from the corresponding segment of the lambda chain of a mouse M-myeloma (MOPC-104) protein with anti-dextran activity.
Comparison of Faunal Equilibrium Turnover Rates on a Tropical Island and a Temperate Island
Authors: Diamond Jared M.
Published: May 2006

Rates of immigration and extinction of bird species on a tropical island, Karkar in the southwest Pacific Ocean, have been estimated from surveys made in 1914 and in 1969. Compared to a temperate-zone island of similar size and isolation (Santa Cruz off southern California), Karkar has a similar extinction rate, but a lower immigration rate expressed as a fraction of the mainland species pool, due to the sedentariness of many tropical forest birds. The probability of extinction is highest for species that are rare (due to narrow habitat requirements, large territory size, competition, recency of colonization, or marginal suitability of habitat), species with “in-and-out” tactics, and populations on small islands.
Synthesis of Amplified DNA That Codes for Ribosomal RNA
Authors: Crippa Marco , Tocchini-Valentini Glauco P.
Published: May 2006

During the amplification stage in ovaries, the complete repetitive unit of the DNA that codes for ribosomal RNA in
Xenopus
appears to be transcribed. This large RNA transcript is found in a complex with DNA. Substitution experiments with 5-bromodeoxyuridine do not show any evidence that a complete amplified cistron is used as a template for further amplification. A derivative of rifampicin, 2′,5′-dimethyl-
N
(4′)benzyl-
N
(4′)[desmethyl] rifampicin, preferentially inhibits the DNA synthesis responsible for ribosomal gene amplification. These results are consistent with the hypothesis that RNA-dependent DNA synthesis is involved in gene amplification.
RNA-Dependent DNA Polymerase: Possible Role in the Amplification of Ribosomal DNA in
Xenopus
oocytes
Authors: Ficq A. , Brachet J.
Published: May 2006

2′,5′ - dimethyl -
N
(4′)benzyl -
N
(4′) - [desmethyl]rifampicin, a derivative of rifampicin, is used to acquire autoradiographic evidence that RNA-dependent DNA synthesis is involved in gene amplification during the early oogenesis of
Xenopus laevis
.
The Uptake of [γ-
3
H] Aminobutyric Acid in the Goldfish Retina
Authors: Lam Dominic M. K. , Steinman Lawrence
Published: May 2006

After goldfish retinas had been incubated for 1 hr with [γ-
3
H]aminobutyric acid, we found by autoradiography that the label was localized to a few restricted types of retinal cells. In particular, external and internal horizontal cells from light-stimulated retinas were more heavily labeled than corresponding cells from retinas kept in darkness. Some other cells and tissues in the retina also incorporated the labeled acid. Light stimulation, however, did not cause a pronounced change in the amount of label associated with these cells. Among these were some heavily labeled cells on the vitreal side of the inner nuclear layer, and scattered grains associated with the ganglion cell and optic nerve layers. Electrophoresis of retinal extracts after incubation with the labeled acid also showed that light-stimulated retinas contained about 40-100% more radioactivity than retinas kept in darkness, and that 90% of this activity remained as [γ-
3
H]aminobutyric acid. The role of the acid in the retina is not known; it is not clear if horizontal cells normally synthesize or store it. The stimulation-dependent accumulation of the labeled acid into horizontal cells suggests that it plays a functional role in these cells.
Partial Purification of Mitochondrial RNA Polymerase from Rat Liver
Authors: Reid B. D. , Parsons Peter
Published: May 2006

Mitochondrial RNA polymerase activity from rat liver has previously been demonstrated in intact organelles. This activity has now been solubilized, partially purified, and shown to be a true polymerase, free of nuclease. The enzyme is derived from mitochondria and is not from contaminating bacteria or nuclear components. The enzyme is distinguished from its nuclear counterparts by its behavior on ammonium sulfate fractionation and lack of inhibition by α-amanitin. Rifamycin inhibits the crude enzyme, but only inconsistently inhibits the more purified preparation.
Specific cleavage of simian virus 40 DNA by restriction endonuclease of
Hemophilus influenzae
Authors: Danna Kathleen , Nathans Daniel
Published: May 2006

A bacterial restriction endonuclease has been used to produce specific fragments of SV40 DNA. Digestion of DNA from plaque-purified stocks of SV40 with the restriction endonuclease from
Hemophilus influenzae
gave 11 fragments resolvable by polyacrylamide gel electrophoresis, eight of which were equimolar with the original DNA. The fragments ranged from about 6.5 × 10
5
to 7.4 × 10
4
daltons, as determined by electron microscopy, DNA content, or electrophoretic mobility.
A Supernatant Factor Involved in Initiation Complex Formation with Eukaryotic Ribosomes
Authors: Zasloff Michael , Ochoa Severo
Published: May 2006

Embryos of the brine shrimp,
Artemia salina
, were used in a study of polypeptide chain initiation in an
in vitro
system from a eukaryote. A protein, isolated from the high-speed supernatant, has been highly purified and shown to have properties that suggest it is the eukaryotic equivalent of the
Escherichia coli
initiation factor F
2
: It promotes the AUG-dependent binding of fMet-tRNA (
E. coli
) to the
Artemia
40S ribosomal subunit, but not to either the 60S or 80S species; the bound fMet-tRNA is placed in a site on the smaller subunit from which it reacts with puromycin upon addition of the 60S subunit; and the activity is sensitive to aurintricarboxylic acid and edeine, specific inhibitors of initiation. The factor, a basic protein of molecular weight about 100,000, is inactivated by
N
-ethylmaleimide, an SH-binding reagent, and is clearly distinct from the
Artemia
elongation factors, T
1
and T
2
. In addition, the factor stimulates the poly(U)-dependent binding of Phe-tRNA (
E. coli
) to the
Artemia
40S ribosomal subunit. This reaction, though similar to the fMet-tRNA-binding reaction, differs in that the bound Phe-tRNA is largely resistant to release by puromycin.
Three Forms of Cytochrome
b
559
and Their Relation to the Photosynthetic Activity of Chloroplasts
Authors: Wada Keishiro , Arnon Daniel I.
Published: May 2006

Spinach chloroplasts were found to contain three forms of cytochrome
b
559
that have the same α-peak at 559 nm, but are distinguished from one another by their oxidation-reduction potentials. The high-potential (H) form (

E
m

about 330-350 mV) is reducible by hydroquinone, the middle-potential (M) form (

E
m

about 50-80 mV) is reducible by ascorbate but not by hydroquinone, and the low-potential (L) form is reducible by dithionite but not by ascorbate. The H form was the predominant one in freshly prepared chloroplasts and was strongly correlated with Photosystem II activity. Chloroplast treatments such as aging, sonication, and mild heating, singly or in combination, brought about a shift of the H to the M form. More drastic treatments resulted in shifts of the H and M forms to the L form.

The role of cytochrome

b
559

as an electron carrier in System II of plant photosynthesis is discussed.
Chemical Induction of Focus-Forming Virus from Nonproducer Cells Transformed by Murine Sarcoma Virus
Authors: Aaronson Stuart A.
Published: May 2006

Focus-forming virus can be induced by chemicals from virus-negative clonal lines of cells transformed by murine sarcoma virus. The viruses activated from such nonproducer cells have the host range and serologic properties of endogenous helper viruses of the cells rather than those of the sarcoma virus used to transform them. The evidence indicates that murine sarcoma virus-transformed nonproducer cells of two species contain the genetic information for both murine sarcoma and helper virus production in an unexpressed form.
Virus-Specific Proteins Synthesized in Encephalomyocarditis Virus-Infected HeLa Cells
Authors: Butterworth Byron E. , Hall Linda , Stoltzfus C. Martin , Rueckert Roland R.
Published: May 2006

The
in vivo
synthesis of encephalomyocarditis-specific proteins was studied by labeling the viral proteins with radioactive amino acids under conditions where host-protein synthesis was almost completely inhibited. To assure recovery of all proteins, intact cells were lysed in hot 1% sodium dodecyl sulfate. These lysates were analyzed by quantitative high-resolution electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. This technique allowed the detection and estimation of the molecular weight of 15 virus-specific polypeptides:
A
, 100,000;
B
, 90,000;
C
, 84,000;
D
, 75,000,
D1
, 65,000;
E
, 56,000; ε, 40,000;
F
, 38,000; α, 34,000; β, 30,000; γ, 23,000;
G
, 16,000;
H
, 12,000;
I
, 11,000; and δ, 9,000. Pulse-chase experiments, in conjunction with cyanogen bromide and tryptic mapping of the isolated polypeptides, indicate that at least three primary gene products (A,F,C), with a cumulative weight of about 220,000, are generated during translation of the RNA genome. Chains
A
and
C
then undergo post-translational cleavages, while
F
remains uncleaved. The proteins generated by the cleavage of
A
include all of the capsid chains (α, β, γ, δ, ε). Those generated by the cleavage of
C
include
D
and
E
. The chains α, β, γ, δ,
E, F, G, H, I
, with a cumulative molecular weight of about 230,000, are stable and are produced in about equimolar amounts. A model for the synthesis of, and a cleavage sequence that accounts for, all of the viral polypeptides is proposed.
Base Composition Differences between Avian Myeloblastosis Virus Transfer RNA and Transfer RNA Isolated from Host Cells
Authors: Randerath Kurt , Rosenthal Leonard J. , Zamecnik Paul C.
Published: May 2006

Using a novel chemical tritium derivative method, we have determined the base composition of 4S RNA isolated from an RNA tumor virus, the avian myeloblastosis virus, and from normal and neoplastic host cells. Extensive differences were detected, particularly with respect to the amount of methylated bases in the viral RNA. The viral 4S RNA, which fulfills the criteria for designation as transfer RNA, appears to be derived from a precursor pool that is different from the precursor population of host-cell 4S RNA. These results are discussed in regard to the possible relationship between transfer RNA of avian mycoblastosis virus and cellular transfer RNA.
Synthetic Derivatives of Polyethyleneimine with Enzyme-Like Catalytic Activity (Synzymes)
Authors: Klotz Irving M. , Royer Garfield P. , Scarpa Ioannis S.
Published: May 2006

A synthetic polymer has been prepared which contains dodecyl groups (to bind small substrate molecules) and methyleneimidazole side chains (as nucleophilic catalytic sites) linked to a polyethyleneimine framework. This macromolecule, with a high local concentration of binding and catalytic groups, catalyzes the hydrolysis of
uncharged
nitrophenyl esters in water at pH 7 with rates markedly greater than previously observed with any other synthetic substances under similar conditions.
Characterization of the Initial Peptide of Qβ RNA Polymerase and Control of Its Synthesis
Authors: Skogerson Lawrence , Roufa Donald , Leder Philip
Published: May 2006

Bacteriophage Qβ RNA directs the cell-free synthesis of two fMet-containing dipeptides prior to the first round of ribosomal translocation. One of these, fMet-Ala, corresponds to the initial segment of the Qβ coat protein. In the present work we take advantage of the fact that translation of the Qβ RNA polymerase cistron is repressed by its coat protein to correlate the other peptide, fMet-Ser, with the Qβ RNA polymerase gene. Our experiments show that repression affects translation of the first two codons of the polymerase cistron, thereby isolating the effect of Qβ coat repressor. Further studies, using single rounds of translocation of the Qβ mRNA and codon-specific tRNAs, allow us to predict the first three amino acids of the Qβ RNA polymerase protein, fMet-Ser-Lys, and to suggest that the initiation region of the Qβ RNA polymerase cistron has the sequence ···AUG·UC[unk]·AA[unk]···
The Hydration of Sodium Ions Crossing the Nerve Membrane
Authors: Hille Bertil
Published: May 2006

The sodium channel of the excitability mechanism in nerve membranes is about as permeable to hydroxylamine and hydrazine cations as it is to sodium ions. It is impermeable to methylamine cations. This selectivity is explained by supposing that an oxygen group in the channel must receive a hydrogen bond from the permeating cation at the same time as the cation lies against another negatively charged oxygen acid. If these conditions are not satisfied the cation cannot permeate. Sodium ions can satisfy this hydrogen-bonding requirement if they have a water of hydration. The H
2
O·Na complex also has almost the same dimensions as the hydroxylamine and hydrazine cations. This hydrated ion is probably part of the critical complex between sodium ions and the selectivity mechanism of the sodium channel.
Optimal Solutions to a Linear Inverse Problem in Geophysics
Authors: Jordan Thomas H. , Franklin Joel N.
Published: May 2006

This paper is concerned with the solution of the linear system obtained in the Backus-Gilbert formulation of the inverse problem for gross earth data. The theory of well-posed stochastic extensions to illposed linear problems, proposed by Franklin, is developed for this application. For given estimates of the statistical variance of the noise in the data, an optimal solution is obtained under the constraint that it be the output of a prescribed linear filter. Proper specification of this filter permits the introduction of information not contained in the data about the smoothness of an acceptable solution. As an example of the application of this theory, a preliminary model is presented for the density and shear velocity as a function of radius in the earth's interior.
Induced Degradation of Glycosaminoglycans in Hurler's and Hunter's Syndromes by Plasma Infusion
Authors: Ferrante Nicola Di , Nichols Buford L. , Donnelly Patricia V. , Neri Giovanni , Hrgovcic Ruzica , Berglund Robert K.
Published: May 2006

The effects of the administration of normal human plasma to patients affected by mucopolysaccharidoses I and II (Hurler's and Hunter's syndromes) have been evaluated. The infusion was followed by a decreased urinary excretion of relatively large molecular weight glycosaminoglycans and by an increased excretion of their products of degradation. Among the latter, products of the degradation of dermatan sulfate and heparan sulfate could be demonstrated.

The results indicate that normal human plasma may contain those “factors” that are involved in the normal degradation of dermatan sulfate and heparan sulfate, that are missing in the diseased states.
Terrestrial and Meteorite Carbon Appear to Have the Same Isotopic Composition
Authors: Libby W. F.
Published: May 2006

The carbon-isotope ratio recently obtained for the carbon found in the Murchison meteorite, which has been shown (by the racemic nature of twelve component amino acids) to be free of terrestrial contamination, agrees with that for average terrestrial sediments. This finding indicates that the earth and the stony meteorites contain carbon of the same isotopic composition.
Photoinactivation of Aldolases by Pyridoxal Phosphate and Its Analogues
Authors: Davis L. C. , Ribereau-Gayon G. , Horecker B. L.
Published: May 2006

Pyridoxal phosphate can act as a specific photosensitizer for amino acid residues in rabbit muscle and spinach leaf aldolases, but the residues affected depend on the pH of the reaction. Below pH 8 one histidine residue per enzyme subunit is destroyed; above pH 8.5 there is little loss of histidine, and photoinactivation is associated with the destruction of specific tyrosine residues, particularly the COOH-terminal residues. Pyridoxal and 4-pyridinecarboxaldehyde are much less effective than pyridoxal phosphate at neutral pH, but are similar to pyridoxal phosphate in their photosensitizing activity at the higher pH. Compounds lacking the aldehyde group or the pyridine ring show little or no activity. A number of other enzymes, including α-glycerophosphate dehydrogenase, glucose-6-phosphate dehydrogenase, and yeast hexokinase, were also photoinactivated in the presence of pyridoxal phosphate; however, rabbit liver aldolase and two isomerases tested were completely resistant. The results suggest that certain enzymes, including rabbit muscle and spinach aldolases, but not rabbit liver aldolase, contain a specific site which interacts with pyridoxal phosphate, and that the conformation of this site changes in the pH range between 8.0 and 8.5
DNA-Dependent RNA Polymerase from Yeast Mitochondria
Authors: Tsai Ming-Jer , Michaelis Georg , Criddle R. S.
Published: May 2006

The DNA-dependent RNA polymerase present in the mitochondria of
Saccharomyces cerevisiae
has been solubilized using a 0.5 M KCI solution, and the soluble enzyme has been purified. Two forms of mitochondrial enzyme were obtained; they differ in their template specificity and metal-ion dependency. The mitochondrial RNA polymerase also differs from enzyme obtained from the nucleus with respect to antibiotic sensitivity and template specificity. Only the nuclear enzyme is sensitive to α-amanitin inhibition. The relative activities of the isolated nuclear and mitochondrial polymerases toward their homologous DNAs are consistent with their
in vivo
functions. The possibilities of bacterial- and nuclear-enzyme contamination of the mitochondrial enzyme preparation have been ruled out. RNA polymerase activity in two petite mutants has been studied. Isolated mitochondria from a petite mutant with no detectable mitochondrial DNA has greatly diminished mitochondrial DNA-dependent RNA polymerase activity, while a petite mutant with only a small change in mitochondrial DNA base composition has normal amounts of enzyme.
Viruses as an Aid to Cancer Therapy: Regression of Solid and Ascites Tumors in Rodents After Treatment with Bovine Enterovirus
Authors: Taylor M. W. , Cordell B. , Souhrada M. , Prather S.
Published: May 2006

Treatment of ascites and solid tumors in mice (Sarcoma-1 and Ehrlich ascites carcinoma) with bovine enterovirus-1 resulted in regression of the tumors without any pathological effect on the animals. Death of mice with lymphatic-leukemia L4946 was delayed after such treatment. The oncolytic specificity of the virus does not appear to involve the production of interferon, but requires specific adsorption of virus to the tumor cells. The specificity of killing extends to cells in culture, since viral-transformed cells and oncogenic cells are susceptible to the virus, in contrast to cells of untransformed lines and cells of primary cultures, which are resistant.

The possibility of utilizing the specificity of nonvirulent viruses in therapeutic treatment of human cancers is considered.
Deficiency of Uncoupler-Stimulated Adenosine Triphosphatase Activity in Tightly Coupled Hepatoma Mitochondria
Authors: Pedersen Peter L. , Eska Terry , Morris Harold P. , Catterall William A.
Published: May 2006

Tightly coupled mitochondria from the well-differentiated hepatoma 7800 failed to exhibit a significant 2,4-dinitrophenol-activated ATPase activity at concentrations of uncoupler sufficient to completely inhibit oxidative phosphorylation. ATPase activity could not be maximally activated by uncoupling agents more potent than 2,4-dinitrophenol, such as carbonylcyanide
p
-trifluoromethoxyphenylhydrazone and 5-chloro, 3-
tert
-butyl, 2′-chloro, 4′-nitrosalicylanilide, nor by Mg
++
after the following treatments: sonication, freezing, detergent lysis, and digestion with trypsin. Gel electrophoresis patterns of the membrane proteins of the hepatome mitochondria revealed neither an absence of any one of the three different types of ATPase subunits characteristic of the homogeneous enzyme purified from normal liver mitochondria, nor a deficiency of the oligomeric molecule. Taken together, these data strongly suggest that the supramolecular structure of the membrane ATPase complex of mitochondria from hepatoma 7800 is altered in such a way that its capacity for ATP hydrolysis is severely diminished.
Covalent Attachment of Diethylstilbestrol to Glutamate Dehydrogenase: Implications for Allosteric Regulation
Authors: Kallos John , Shaw K. P.
Published: May 2006

An affinity labeling reagent for the estrogenic-binding site of bovine liver L-glutamate dehydrogenase (EC 1.4.1.3) was prepared by conversion of diethylstilbestrol to its alkylating analogue, bromoacetyldiethylstilbestrol. Under standard assay conditions, the analogue acted as a reversible allosteric ligand with regulatory activity much like that of diethylstilbestrol. However,
incubation
of the enzyme with the alkylating agent in the presence of DPNH resulted in a permanent decrease in glutamate (X form) and an increase in alanine (Y form) activities, and in covalent attachment of diethylstilbestrol in the ratio of 1 mol per subunit (of particle weight 52,000). The brominated analogue behaved as an affinity label that mimicked the allosteric effects of diethylstilbestrol. Diethylstilbestrol protection of the enzyme against alkylation by bromoacetylated sterol suggested competition for the same binding site, while ADP protection indicated a shift of protein equilibrium into the X form. The diethylstilbestrol-enzyme compound was desensitized (relative to the native enzyme) to allosteric reagents such as ADP and GTP. The results were consistent with conformational freezing of the modified protein molecule into the Y form.
A New Basis for Interpreting the Circular Dichroic Spectra of Proteins
Authors: Saxena V. P. , Wetlaufer D. B.
Published: May 2006

Experimental circular dichroic (CD) spectra of three proteins have been combined with estimates of the content of peptide-chain structural modes obtained from x-ray diffraction studies of the same proteins. Solution of the simultaneous equations at a series of wavelengths permits the construction of a CD spectrum for each of three structural modes: α-helix, β-structure, and the so-called “random”. The CD spectra thus obtained are compared with those obtained from polypeptide models. The α-helical spectra from the two approaches are nearly congruent, the β-structure spectra are in fair agreement, and the third forms agree qualitatively, but are substantially different quantitatively. Comparisons are made between the present approach and earlier approaches to interpreting protein CD spectra. Certain advantages of the present approach are indicated.
Initiation of DNA Synthesis in Cell Cultures by Colcemid
Authors: Vasiliev J. M. , Gelfand I. M. , Guelstein V. I.
Published: May 2006

Mitotic inhibitors (colcemid, colchicine, and vinblastine) initiate DNA synthesis in dense stationary cultures of mouse embryo fibroblast-like cells. This initiation is not due to any changes in local cell population density. Relationships between the activation of proliferation and other changes of interphase fibroblast-like cells produced by the mitotic inhibitors (disappearance of cytoplasmic microtubules and activation of movements of cell surface) are discussed.
The Effect of Genetic Linkage on the Mean Fitness of a Population
Authors: Lewontin R. C.
Published: May 2006

If many gene loci are kept in a segregating state by natural selection, the equilibrium frequencies of the genotypes in the population may be a function of the amount of recombination among the genes. It is shown that if the equilibrium vector of gametic frequencies is a continuous function of the set of recombination frequencies among genes, then the mean fitness of the population at equilibrium is a maximum in the absence of recombination. Thus, in general, restriction of recombination increases fitness.
Three-Dimensional Molecular Models of Bacterial Cell Wall Mucopeptides (Peptidoglycans)
Authors: Kelemen M. V. , Rogers H. J.
Published: May 2006

Molecular models have been built of mucopeptides (peptidoglycans) from various species of bacteria. If pairs of glycan chains are hydrogen-bonded as are those of chitin, the carboxyl groups of muramic acid are so oriented that a regular three-dimensional structure can be built. Helical conformation of the peptides is not likely, but pseudo-β conformation gives the possibility of multiple interpeptide hydrogen bonding. Calculations of the expected dimensions of the cell wall from the model for mucopeptide give results of the right order for bacilli. The effect of the configuration of the amino acids on the conformation of the peptide has been examined.
Extrinsic Cotton Effects in Hapten—Carrier and Hapten—Antibody Interactions
Authors: Reid Vincent , Glaser Michael , Kennett Roger , Singer S. J.
Published: May 2006

Two homogeneous univalent hapten-protein conjugates, prepared by the covalent attachment of a single 2,4-dinitrophenyl (DNP-) or 2,4,6-trinitrophenyl (TNP-) side chain to the cysteine-SH in the active site of the enzyme papain, have been found to exhibit large Cotton effects in the wavelength region of the absorption bands of the DNP or TNP groups. This indicates that the DNP or TNP groups are noncovalently bound to some asymmetric region(s) of the papain molecule. These homogeneous papain conjugates are antigens that can elicit anti-DNP or anti-TNP antibody production in mice or rabbits. It is suggested that the noncovalent binding of a hapten to the surface of its carrier protein may profoundly affect the characteristics of the anti-hapten antibodies that are elicited. It has also been observed that the specific binding of these papain conjugates, and of the simple haptens DNP-lysine or TNP-lysine, to anti-hapten antibodies produces characteristic extrinsic Cotton effects.
Analysis of the Events Leading to SV40-Induced Chromosome Replication and Mitosis in Primary Mouse Kidney Cell Cultures
Authors: May Evelyne , May Pierre , Weil Roger
Published: May 2006

Abortive infection with simian virus 40 in confluent, “contact-inhibited”, mouse kidney cell cultures was studied. The sequential events, in individual cells, are tentatively represented by the simplified scheme: (
a
) transcription of early virus-specific (messenger) RNA; (
b
) appearance of T-antigen; (
c
) [psychrosensitive event(s)]; (
d
) chromosome replication; (
e
) normal or abnormal mitosis. No evidence for the replication of viral progeny DNA was obtained. The sequence of the events (
a
)-(
d
) is analogous to that observed in contact-inhibited mouse kidney tissue culture cells during lytic infection with polyoma virus.
Local Supply of Energy to the Fast Axoplasmic Transport Mechanism
Authors: Ochs Sidney
Published: May 2006

Local anoxia of a small region of cat sciatic nerves causes a block of fast axoplasmic transport
in vitro
. Activity becomes dammed up at the face of the anoxic region, and falls off rapidly distally just inside the anoxic region. Such blocks were reversible if they were removed within 1 hr. Earlier studies had given evidence that fast axoplasmic transport is closely dependent on ATP derived from oxidative metabolism. The present results indicate that ATP is required all along the length of the nerve fiber to supply a hypothesized “transporting filament” mechanism of fast transport.
An Adenylic Acid-Rich Sequence in Messenger RNA of HeLa Cells and Its Possible Relationship to Reiterated Sites in DNA
Authors: Darnell J. E. , Wall R. , Tushinski R. J.
Published: May 2006

Messenger RNA from HeLa cells contains, as part of the polynucleotide chain, RNase-resistant sequences that are labeled by adenosine but not by uridine. Heterogeneous nuclear RNA also contains adenylate-rich RNase-resistant regions, but in lower proportion than messenger RNA. Hybridization to DNA of
32
P-labeled messenger RNA reveals that some of the adenylate-rich region is included in the rapidly-hybridizing fraction.
Effect of Double-Stranded Viral RNA on Mammalian Cells in Culture
Authors: Cordell-Stewart B. , Taylor Milton W.
Published: May 2006

During bovine enterovirus infection of Ehrlich ascites tumor cells, large amounts of double-stranded RNA accumulate. Addition of this double-stranded RNA to uninfected cells leads to rapid cell death. This is not a result of infectious virus production. Neither single-stranded RNA nor heat-denatured double-stranded RNA has this effect. Similar experiments with synthetic double-stranded polymers, poly(I)·poly(C) and poly(A)·poly(U), show that they are only slightly toxic at the concentrations used. The effect of the double-stranded RNA is nonspecific for cells of different origins. The implications of this finding in relation to the cytopathic effects of picornavirus and to cancer chemotherapy are discussed.
Structural Basis of the A14 and A15 Allotypic Specificities in Rabbit Immunoglobulin G
Authors: Appella E. , Chersi A. , Mage R. G. , Dubiski S.
Published: May 2006

The structural basis for the A14 and A15 allotypic specificities of rabbit immunoglobulin G was investigated with Fe fragments prepared from homozygous rabbits. The presence of threonine in the Cγ2 region (position 309: Eu numbering) correlates with the A14 allotype; the presence of alanine at this same position correlates with the A15. Now that the sequence of the Cγ2 region of rabbit IgG has been completely elucidated, a high degree of homology of the constant region domains of rabbit and human γ chains is apparent (about 60-80%).
RNA-Dependent RNA Polymerase Activity in Influenza Virions
Authors: Penhoet Edward , Miller Henry , Doyle Michael , Blatti Stanley
Published: May 2006

An RNA-dependent RNA polymerase activity has been detected in purified preparations of influenza virus. In contrast to the replicase activity induced in influenza-infected cells, the virion-associated enzyme has an absolute requirement for Mn
++
. Most of the RNA synthesized
in vitro
is complementary to virion RNA.
Stability of Plane Poiseuille Flow to Periodic Disturbances of Finite Amplitude, III
Authors: Pekeris C. L. , Shkoller B.
Published: May 2006

The stability of plane Poiseuille flow to periodic disturbances of finite amplitude was reinvestigated by the use of 55 harmonics instead of five in the Orr-Sommerfeld expansion, but all the (20) overtones in each harmonic were dropped. The fundamental mode was chosen as the one of lowest phase velocity

c
r

, so as to enhance the wall effects. The neutral curve obtained gives values of the critical amplitude λ

c

that are considerably higher than in the previous calculation. Near the critical Reynolds number, the neutral curve approaches the values derived previously by an analytical method.
Regulation of the Synthesis of Choline-
O
-Acetyltransferase and Thymidylate Synthetase in Mouse Neuroblastoma in Cell Culture
Authors: Rosenberg Roger N. , Vandeventer Larry , Francesco Laura De , Friedkin Morris E.
Published: May 2006

The specific activity of mouse neuroblastoma choline-
O
-acetyltransferase (EC 2.3.1.6.) increased 5.7-fold when the rate of cell division was restricted (as compared to cells kept rapidly dividing for 9 days); the specific activity of mouse neuroblastoma thymidylate synthetase increased 2.4-fold when nondividing cells again entered the logarithmic phase of cell growth. The highest specific activities for choline-
O
-acetyltransferase and lowest specific activities for thymidylate synthetase were obtained from cultures where cell division was restricted; the opposite result was observed when the cells were growing rapidly. Thus, the regulation of these two enzymes is out of phase with respect to each other and is dependent on the rate of cell division. The inverse relationship for the regulation of these two enzymes is discussed in relation to the needs of mitotic versus differentiated neuroblastoma cells.
An Attempt to Locate the Non-helical and Permissively Helical Sequences of Proteins: Application to the Variable Regions of Immunoglobulin Light and Heavy Chains
Authors: Wu T. T. , Kabat Elvin A.
Published: May 2006

From a consideration of (ϕ, Ψ) values of the amino acids of myoglobin, lysozyme, the α and β chains of horse oxyhemoglobin, tosyl-α-chymotrypsin, and carboxypeptidase A, an empirical procedure of predicting whether amino-acid residues in proteins are in a non-helical or may be in a helical conformation has been developed. The conformation of an amino acid at any position
n
is considered to be influenced by its nearest neighbors (the amino acids at positions
n
+ 1 and
n
- 1), and the (ϕ, Ψ) values of the middle amino acid
n
for the various tripeptide sequences in the known proteins are tabulated. If helical, the (ϕ, Ψ) values are plotted to define a helical (ϕ, Ψ) domain. A 20 × 20 table for all tripeptides (
n
- 1)-(
n
)-(
n
+ 1) taken sequentially for the entire chain was constructed; it lists the number of instances in which helical and non-helical conformations for the amino acids at position
n
were found. Certain sequences are found to be associated exclusively with non-helical and others exclusively with helical conformations, whereas many sequences may be either helical or non-helical. The distribution of non-helical residues serves to limit stretches of permissively helical regions; these are then further examined by the helical wheel method. As applied to cytochrome
c
from 18 species, the only permissively helical segment found was the stretch 91-101 near the C-terminus. For the variable regions of three light and three heavy chains of immunoglobulins, upper limits of 12 and 17% α-helix, respectively, were obtained.
Rapid Change in Water Flux Induced by Auxins
Authors: Kang Bin G. , Burg Stanley P.
Published: May 2006

Auxin (indole-3-acetic acid) enhances movement of tritiated water into and out of stem segments of etiolated peas. The time required for water in the tissue to attain one-half equilibrium with water in the surrounding solution is significantly shorter and the initial flux rate is higher in auxin-treated sections. The response is one of the most rapid to auxin, occurring well within 1 min after application of the hormone. This suggests that an action of auxin on the membrane system occurs before or coincident with auxin-induced enhancement of growth and wall elastic extensibility.
Stereospecific and Nonspecific Interactions of the Morphine Congener Levorphanol in Subcellular Fractions of Mouse Brain
Authors: Goldstein Avram , Lowney Louise I. , Pal B. K.
Published: May 2006

A method is described for analyzing the association of the opiate narcotic levorphanol with brain tissue into three components: nonsaturable, saturable nonspecific, and saturable stereospecific. The method may be of general applicability for the study of the interaction of drugs with body tissues. In mouse brain the stereospecific binding of levorphanol represents only 2% of the total association of drug with tissue, and it was found only in certain membrane fractions. The material responsible for the stereospecific binding might be the opiate receptor.
A Fraction of the Ventricular Myocardium That Has the Specificity of the Cardiac Beta-Adrenergic Receptor
Authors: Lefkowitz Robert J. , Haber Edgar
Published: May 2006

The 78,000 ×
g
microsomal fraction of canine ventricular myocardium effected a 20-fold concentration of [
3
H]norepinephrine from a 10
-9
M solution. The [
3
H]norepinephrine bound was displaced by physiologic concentrations of the beta-adrenergic catecholamines isoproterenol, epinephrine, and norepinephrine, in that order, which is the order of effectiveness of their actions on the force and rate of cardiac contraction. Alpha-adrenergic compounds did not displace [
3
H]norepinephrine until concentrations four orders of magnitude greater were reached. The beta-adrenergic blocker propranolol displaced at 10
-6
M, whereas the alpha-adrenergic blocker phentolamine was inactive. Metabolites of the catecholamines did not compete for this binding site. It is concluded that, on the basis of specificity and affinity of binding, these microsomal particles are likely to contain the beta-adrenergic receptor.
Interaction of Eukaryote Initiator Methionyl-tRNA with the Eukaryote Equivalent of Bacterial Elongation Factor T and Guanosine Triphosphate
Authors: Richter Dietmar , Lipmann Fritz , Tarragó Adela , Allende Jorge E.
Published: May 2006

The initiator tRNA, methionyl-tRNA
i
Met
, of yeast and wheat germ forms relatively unstable ternary complexes with their corresponding elongation factors T and GTP. Such complexes can be demonstrated only with fast separation techniques such as Sephadex G-50 and Millipore filtration, but not with the slow Sephadex G-100 method, although both techniques yield stable ternary complexes with all other aminoacyl-tRNAs, including the internal Met-tRNA
m
Met
. To bind yeast-initiating Met-tRNA
i
Met
to ribosomes, initiation factors present in a ribosomal wash fraction from yeast are needed.
Decrease in Liver Aromatic L-Amino-Acid Decarboxylase Produced by Chronic Administration of L-Dopa
Authors: Dairman Wallace , Christenson James G. , Udenfriend Sidney
Published: May 2006

L-Dopa, an intermediate in the biosynthesis of catecholamines, is now widely used in the treatment of parkinsonism. A number of clinical observations suggested that L-dopa may induce changes in its own metabolism during the course of therapy. In the present study, it was found that when L-dopa was administered to rats, the activity of liver aromatic L-amino-acid decarboxylase, the enzyme which catalyzes the conversion of dopa to dopamine, was reduced by as much as 50%. There were no corresponding changes in enzyme activity in heart, adrenals, kidneys, and brain. Decarboxylase activity in the liver continued to decrease for at least 5 days after the last dose of L-dopa. The reduction of enzyme activity in the liver occurred when L-dopa was administered either subcutaneously or orally at doses comparable to those used clinically.
In vitro
and
in vivo
experiments indicated that this action of L-dopa is not due to some effect on the cofactor, pyridoxal phosphate. Immunological evidence was obtained that enzyme protein is reduced in the same proportion as enzyme activity. By a reduction of decarboxylase activity in liver without any affect on the enzyme in brain, more L-dopa should be made available to the brain for decarboxylation to dopamine. These findings may explain the clinical observations that the therapeutic efficacy of the drug increases with continued administration.
Toluene-Treated
Escherichia coli
Replicate Only That DNA Which Was About To Be Replicated
In Vivo
Authors: Burger Richard M.
Published: May 2006

DNA density-transfer experiments with
Escherichia coli
strain B/r indicate that the DNA synthesized from exogenous substrates after treatment with toluene is made semiconservatively from that region of the chromosome about to be replicated at the time of toluene treatment. Up to 15% of the chromosome is replicated, at a rate 10-20% of that
in vivo
. A minor fraction of nonconservatively replicated DNA is readily distinguished.
Effect of Catecholamines on the Adenosine 3′:5′-Cyclic Monophosphate Concentrations of Clonal Satellite Cells of Neurons
Authors: Gilman Alfred G. , Nirenberg Marshall
Published: May 2006

The effects of potential neurohormones on the intracellular concentrations of adenosine 3′:5′-cyclic monophosphate have been examined with three clonal lines of cultured glial tumors. In all cases, norepinephrine and isoproterenol produced striking elevations of the intracellular concentrations of the cyclic nucleotide. The response was mediated by a β-adrenergic receptor. This effect is hypothesized to represent a molecular mechanism for neuronal-glial communication coupled to concurrent communication between neurons.