bluuebunny/crossref_metadata_2025 huggingface dataset:
HIGH SEQUENCE DIVERSITY IN THE RNA SYNTHESIZED AT THE LAMPBRUSH STAGE OF OÖGENESIS
Authors: Davidson Eric H. , Hough Barbara R.
Published: May 2006

Many diverse RNA's are synthesized in the lampbrush stage oöcyte of
Xenopus
, as shown by the presence of different nucleotide sequences in the RNA population. This fact has been established by hybridizing lampbrush stage oöcyte RNA with an isolated
nonrepetitive
fraction of
Xenopus
DNA.
UROPORPHYRINOGEN III COSYNTHETASE IN HUMAN CONGENITAL ERYTHROPOIETIC PORPHYRIA
Authors: Romeo Giovanni , Levin Ephraim Y.
Published: May 2006

Activity of the enzyme uroporphyrinogen III cosynthetase in hemolysates from five patients with congenital erythropoietic porphyria was much lower than the activity in control samples. The low cosynthetase activity in patients was not due to the presence of a free inhibitor or some competing enzymatic activity, because hemolysates from porphyric subjects did not interfere either with the cosynthetase activity of hemolysates from normal subjects or with cosynthetase prepared from hematopoietic mouse spleen. This partial deficiency of cosynthetase in congenital erythropoietic porphyria corresponds to that shown previously in the clinically similar erythropoietic porphyria of cattle and explains the overproduction of uroporphyrin I in the human disease.
EMISSION-LINE OBJECTS PROJECTED UPON THE GALACTIC BULGE
Authors: Herbig G. H.
Published: May 2006

Low-dispersion slit spectrograms have been obtained of 34 faint objects that lie in the direction of the galactic bulge and have the Hα line in emission upon a detectable continuum. Eleven of these are certain or probable symbiotic stars. A rough comparison with R CrB stars in the same area suggests that these brightest symbiotics in the bulge have in the mean

M
v

≈ -3 to -4, which suggest Population II red giants rather than conventional Population I M-type objects. The sample also contains a number of hot stars having H and [O II] or [O III] in emission, as well as four conventional Be stars, and six certain or possible planetary nebulae.
ON THE PROPORTIONS BETWEEN SOME AREAS OF THE FIRST CERVICAL SEGMENT OF THE SPINAL CORD OF PRIMATES
Authors: Schön Miguel A. , Straus William L.
Published: May 2006

It has been generally supposed that the dorsal funiculi occupy a relatively larger part of the highest segments of the spinal cord in man than in any other primate. We have taken planimetric measurements of the total area of the cord, dorsal funiculi, and total gray in the uppermost segments of the spinal cord of a wide variety of primates. Our results indicate that the largest values for the proportions dorsal funiculi/total white matter and dorsal funiculi/ventrolateral funiculi are found in gorilla, chimpanzee, and orang, rather than in man. Moreover, man has, on the average, smaller dorsal funiculi in relation to either the total white or ventrolateral funiculi than any of the three great apes.
AN L-GLUTAMINE REQUIREMENT FOR INTERCELLULAR ADHESION
Authors: Oppenheimer Steven B. , Edidin Michael , Orr Charles W. , Roseman Saul
Published: May 2006

Intercellular adhesion presumably involves components of the cell surface, but the chemical nature of these substances is not known. The present studies suggest that complex carbohydrates are required for the adhesion of at least one type of animal cell. Single cells obtained from “embryoid bodies,” the ascites-grown form of a mouse teratoma, aggregated in a complex tissue culture medium, but not in a glucose balanced salts solution. The active component of the tissue culture medium was identified as L-glutamine, and the only compounds found to replace it were the hexosamines D-glucosamine and D-mannosamine. A variety of studies indicated that the three compounds were active as a consequence of metabolic reactions. These results are consistent with known metabolic pathways and indicate that the conversion of nonadhesive to adhesive teratoma cells requires the synthesis of glycoproteins, glycolipids, and/or polysaccharides.
INDUCTION OF MELANIN SYNTHESIS IN ALBINO MOUSE SKIN BY DNA FROM PIGMENTED MICE
Authors: Ottolenghi-Nightingale Elena
Published: May 2006

Skin cells from albino mouse embryos have been shown to synthesize melanin after exposure to a nucleoprotein fraction of cells from pigmented mice. Although transformed clones were not found in any of 37 control experiments, at least 15 transformations took place in 10 of a series of 49 experiments using undegraded DNA. The active component in the transforming material appears to be DNA because DNase-treated preparations did not induce melanin synthesis.
RELEASE OF TRAPPED MARKER FROM LIPOSOMES BY THE ACTION OF PURIFIED COMPLEMENT COMPONENTS
Authors: Haxby J. A. , Götze O. , Müller-Eberhard H. J. , Kinsky S. C.
Published: May 2006

Liposomes containing trapped glucose marker were prepared from the chloroform-soluble fraction of sheep erythrocyte membranes. These liposomes release glucose when incubated with rabbit anti-sheep erythrocyte serum and a source of complement. Experiments with purified human complement components show that loss of marker is absolutely dependent on the presence of components 2 and 8. An absolute requirement for component 9 cannot be demonstrated, although it stimulates glucose release from the liposomes. These results establish a parallelism between the response of biological membranes and liposomal membranes to antibody and complement.
RADIOIMMUNOASSAY FOR THE MEASUREMENT OF ADENOSINE 3′,5′-CYCLIC PHOSPHATE
Authors: Steiner A. L. , Kipnis D. M. , Utiger R. , Parker C.
Published: May 2006

A sensitive and specific radioimmunoassay for adenosine 3′,5′-cyclic phosphate (cyclic AMP) has been developed which allows measurement of the nucleotide in extracts of 5-10 mg of tissue. The radioimmunoassay is sufficiently specific for cyclic AMP to eliminate the need for prior chromatographic separation of the cyclic nucleotide from other tissue nucleotides. The radioimmunoassay system is based upon competition of cyclic AMP with a labeled cyclic AMP derivative of high specific activity for binding sites on an antibody specific for the cyclic nucleotide. Antibody to cyclic AMP was obtained by immunizing rabbits with an antigen prepared by conjugating succinyl cyclic AMP with human serum albumin. A high specific activity derivative of cyclic AMP was prepared by synthesizing succinyl cyclic AMP tyrosine methyl ester (SCAMP-TME) and iodinating the phenolic hydroxyl group of the tyrosine moiety with
125
I. Free and antibody-bound
125
I-SCAMP-TME were separated by precipitation of the antibody-bound fraction with a second antibody (goat anti-rabbit gamma globulin). Displacement of
125
I-SCAMP-TME by unlabeled cyclic AMP when plotted as a semilogarithmic function was linear over a concentration range of 2-100 picomoles. The specificity of the antibody was tested against structurally related nucleotides, nucleosides, and purine bases. All had less than 0.005 per cent of the potency of cyclic AMP in inhibiting
125
I-SCAMP-TME binding. The marked differences in affinity of the various cyclic nucleotides to cyclic AMP antibody would suggest that antibodies can be developed for each of the cyclic nucleotides by the principles used in this work.
TEMPERATURE AND MANGANESE AS DETERMINING FACTORS IN THE PRESENCE OF DIATOM OR BLUE-GREEN ALGAL FLORAS IN STREAMS
Authors: Patrick Ruth , Crum Bowman , Coles John
Published: May 2006

Diatoms are usually the major component of the algal flora in many streams, although green and blue-green algae may be present. These experiments were designed to determine if high temperature or a shift in the chemical composition of the water might bring about a dominance of blue-green algae and/or green algae rather than a dominance of diatoms in the algal flora.

The results of these experiments indicate that an average temperature of 34° to 38°C results in a shift of dominance in the algal flora from diatoms to blue-green algae. Furthermore, a blue-green and green algal flora of species typically found in organically polluted water in favored if the manganese content is a few parts per billion. If the manganese content averaged 0.02-0.043 mg/liter in the natural stream to 0.04-0.28 mg/liter in the recycled water experiment, a diatom flora remained dominant.
THE OCCURRENCE OF SUBSTANCES IN HUMAN PLASMA CAPABLE OF INDUCING THE ENZYME δ-AMINOLEVULINATE SYNTHETASE IN LIVER CELLS
Authors: Kappas Attallah , Song Chull S. , Sassa Shigeru , Levere Richard D. , Granick S.
Published: May 2006

We have demonstrated the presence, in the plasma of several patients with acute intermittent porphyria, of a substance which strongly induced the synthesis of porphyrins in chick embryo liver cells growing in primary culture. The induction response evoked by this humoral agent was in all respects similar to that elicited by drugs and hormones which are known to enhance porphyrin production by inducing the
de novo
formation of δ-aminolevulinate synthetase, the rate-limiting enzyme in this pathway. Inducing properties were not found in the plasma of normal individuals or in that from porphyric patients in remission. Significant inducing activity was, however, found in the plasma of some normal subjects ingesting drugs or contraceptive steroid mixtures.

The occurrence of a potent inducer of δ-aminolevulinate synthetase in the plasma of certain porphyric patients may have clinical significance for these genetically susceptible individuals. It will also permit chemical characterization of those humoral agents which may be related to the episodic exacerbations of this hereditary liver disease.
THE RELATIONSHIP OF THE INFLUENZA VIRUS INHIBITORY ACTIVITY OF GLYCOPROTEINS TO THEIR MOLECULAR SIZE AND SIALIC ACID CONTENT
Authors: Springer Georg F. , Schwick H. Gerhard , Fletcher Mary Ann
Published: May 2006

Twenty-four different glycoproteins were investigated for their ability to inhibit hemagglutination by the A/PRS and the B/Md influenza virus strains. A relationship between activity, the molecular size, and sialic acid content was found. This relationship was readily shown for the A/PR8 virus if the properties of the glycoproteins were compared with one another on a per cent basis. A proportion of approximately 1:1:1 for activity (weight basis) to moles sialic acid content to molecular weight existed for each inhibitory glycoprotein with more than 3 per cent sialic acid, on comparison with any other active glycoprotein.

A 1:3 correspondence between viral subunit and sialic acid residues of the inhibitor ovine submaxillary mucin was found experimentally and confirmed by calculation on a molecular model. The most potent inhibitors, were the antigens of the human blood-group MN system and the Tamm-Horsfall urinary glycoprotein.
STRUCTURE AND OPTICAL ACTIVITY IN METAL COMPLEXES, VI. INTERACTION OF HISTIDINE WITH COPPER(II) IN SOLUTION
Authors: Wellman Keith M. , Wong Boon-Khin
Published: May 2006

The species existing in aqueous solution at pH 8.3 when copper(II) interacts with two equivalents of L-histidine has been studied by a variety of techniques. The evidence is consistent with a fluctuating type of coordination for the histidinato-copper(II) complex, which varies according to conditions and other coordinating ligands involved.
INDUCTION OF TRANSMISSIBLE LYMPHOMAS IN SYRIAN HAMSTERS BY APPLICATION OF DNA FROM VIRAL HAMSTER PAPOVAVIRUS-INDUCED TUMORS AND BY CELL-FREE FILTRATES FROM HUMAN TUMORS
Authors: Graffi A. , Bender E. , Schramm T. , Kuhn W. , Schneiders F.
Published: May 2006

DNA isolated from skin epitheliomas containing papovavirus induced lymphomas within four to eight weeks in 40 to 50 per cent of newborn Syrian hamsters injected. This DNA effect was eliminated by DNase but not by RNase and was not induced by DNA preparations of transplanted epitheliomas or the induced lymphomas. Lymphomas were similarly induced by cellfree filtrates from certain human tumors such as gastric carcinomas and ovarian tumors. Little or no lymphoma effects were observed following injections with filtrates derived from normal human or animal tissues or human blood. The lymphomas induced by DNA and human tumors were transmissible by cell-free filtrates to newborn Syrian hamsters; however, successful serial passage, like the primary lymphomas induced by the DNA preparations, depended upon the use of a newborn hamster from a special breeding colony of hamsters.
CHLOROQUINE RESISTANCE IN MALARIA: A DEFICIENCY OF CHLOROQUINE BINDING
Authors: Fitch Coy D.
Published: May 2006

Chloroquine-
14
C was used to study the processes which concentrate chloroquine in mouse red blood cells infected with chloroquine-sensitive or with chloroquine-resistant
Plasmodium berghei
. The initial rates of uptake and exchange of chloroquine-
14
C were both too fast to measure, yet large concentration gradients were maintained by the cells. When red blood cells were exposed to 10
-8
M
chloroquine at 22°C, with pH between 7.2 and 7.4, steady-state gradients of chloroquine-
14
C were approximately 600:1 (cells:medium) for cells infected with chloroquine-sensitive parasites, 100:1 for cells comparably infected with chloroquine-resistant parasites, and 14:1 for uninfected cells. The processes responsible for these gradients were saturable, in agreement with the proposal of chloroquine binding to cellular constituents. No degradation of chloroquine was detected.

The major difference between the chloroquine-sensitive and -resistant parasites was deficiency of high-affinity binding of chloroquine by cells infected with chloroquine-resistant parasites. This deficiency explains the reduced ability of chloroquine-resistant parasites to concentrate chloroquine, and it suggests that chloroquine resistance is due to a decrease in the number, affinity, or accessibility of chloroquine receptor sites on a constituent of the malaria parasite.
RELATIVE DIFFUSIVITIES OF METHANE IN WATER AND CARBON TETRACHLORIDE
Authors: Hildebrand Joel H.
Published: May 2006

Methane diffuses in water at 25°C 3/5 as fast as it does in carbon tetrachloride. Since diffusivity depends mainly upon temperature, viscosity of the solvent, and molecular cross section of the diffusant, and since viscosities of H
2
O and CCl
4
at 25°C are almost identical, one may infer that molecules of CH
4
in H
2
O are not imprisoned in “icebergs,” and are retarded only by hydrogen bonds, not by encounters with “ice-like” aggregates.
Changes in the Physical State of DNA during Replication in Regenerating Liver of the Rat
Authors: Berger Henry , Irvin J. Logan
Published: May 2006

Evidence is presented which demonstrates that DNA synthesis in regenerating liver is discontinuous. In pulse-labeling experiments from 30 seconds to 10 minutes, the earliest detectable intermediate in DNA replication appears to be double-stranded DNA which has a significant degree of single-stranded character probably due to the existence of gaps in the newly synthesized strand. The label begins to move into completely double-stranded DNA 10-30 minutes after the commencement of labeling. The average molecular weight of the single-stranded „unit” of DNA replication is determined to be approximately 7.5 million. Smaller units may be produced but not observed as a result of imperfect synchronization of DNA synthesis.
The Relationship between Glucocorticoid Binding and Tyrosine Aminotransferase Induction in Hepatoma Tissue Culture Cells
Authors: Baxter John D. , Tomkins Gordon M.
Published: May 2006

Glucocorticoid receptors with many properties suggesting their involvement in the hormonal induction of tyrosine aminotransferase have been detected in rat hepatoma tissue culture cells. These „specific receptors” approach saturation as the steroid concentrations required for maximal induction are reached. Inducer analogs influence cortisol binding to the specific receptors in direct relation to their influence on cortisol induction. The inducer association with and dissociation from specific receptors are rapid enough to account for the kinetics of induction and deinduction. Chromatographic studies suggest the specific receptors bind unaltered dexamethasone and cortisol. „Nonspecific” association of steroids with the cells also occurs and can be distinguished from specific binding.
Isolation of a Cholinergic Proteolipid Receptor from Electric Tissue
Authors: La Torre José L. , Lunt Glenys S. , De Robertis E.
Published: May 2006

A proteolipid protein having a high affinity for methyl
14
C-hexamethonium,
3
H-
p
-(trimethylammonium)-benzene diazonium fluoroborate, and (acetyl-1-
14
C)choline chloride was isolated and purified from the electric tissue of
Torpedo marmorata
and
Electrophorus electricus
. At variance with the „receptor proteolipid” from the brain the one from electric tissue apparently does not bind atropine sulfate.
Template Activity of Liver Chromatin Increased by
in Vivo
Administration of Insulin
Authors: Morgan Carl R. , Bonner James
Published: May 2006

The hypothesis that insulin may serve as a derepressor of genetic information in the liver of diabetic rats has been tested by comparing the template activity for RNA synthesis of chromatin from liver of insulin-treated diabetic rats to that of chromatin from liver of insulin-deficient diabetic rats. The template activity of the chromatins of insulin-treated diabetic rats is found to be 28 per cent greater than that of chromatin from liver of diabetic rats not treated with insulin. Time course studies show that the template activity of liver chromatin of rats injected with a single dose of insulin reaches a peak at two hours, which is some hours before the appearance of a typical insulin-induced liver enzyme, glucokinase. We conclude that insulin derepresses genetic material of the diabetic liver genome that is repressed in the absence of insulin.
The Mitochondrial Ribosome of
Xenopus laevis
Authors: Swanson Ronald F. , Dawid Igor B.
Published: May 2006

A mitochondrial ribosome with an approximate sedimentation coefficient of 60 S has been isolated from the ovary of the South African clawed toad,
Xenopus laevis
. This ribosome is active in a submitochondrial protein-synthesizing system. It contains two species of RNA, designated as „21S” and 13S RNA, which have sequences complementary to mitochondrial DNA and share no detectable sequence homology with cytoplasmic ribosomal RNA.
Axonal Growth from Insect Neurons in Glia-Free Cultures
Authors: Chen J. S. , Levi-Montalcini R.
Published: May 2006

Mechanical dissociation of nerve and glial cells from 16-day embryos of the cockroach
Periplaneta americana
and their subsequent culture in a Co
2
-conditioned, chemically defined medium results in the survival of neurons but not of glial cells. The dissociated nerve cells remain alive and in excellent condition for many months and build a dense fibrillar network in presence of foregut explants from the same embryos. These explants are invaded by numerous and large fiber bundles emerging from the fibrillar network. The morphological characteristics of nerve cells and the structural and ultrastructural features of nerve bundles in long-term glia-free culture are described.
Colony Inhibition of Fibroblasts from Chimeric Dogs Mediated by the Dogs' Own Lymphocytes and Specifically Abrogated by Their Serum
Authors: Hellström I. , Hellström K. E. , Storb R. , Thomas E. D.
Published: May 2006

Nine canine irradiation chimeras were studied between 173 days and 7.5 years after 1200 to 1500 r of total body irradiation and transplantation of allogeneic bone marrow. Skin fibroblasts from chimeras and normal dogs were tested for colony inhibition by exposure to sera and peripheral blood lymphocytes from both chimeric and normal dogs. Lymphocytes from the chimeric dog were found to inhibit colony formation by its „own” fibroblasts while lymphocytes from other chimeras or from normal dogs did not. Serum from the chimera specifically abrogated this inhibitory effect. These results indicate that the immunological „tolerance” of the chimeric dog is mediated
in vivo
by blocking serum factors.
Selection and Polygenic Characters
Authors: Slatkin Montgomery
Published: May 2006

A mathematical model is developed which describes the effect of selection on polygenic or continuously varying phenotypic characters. For the simplest case the standard deviation of a phenotypic character in a population cannot be greater than √2β where β is the expected deviation of the offspring from the average of the parents' types. This is found to carry over to density-dependent selection, and it indicates that there are limits to the amount of phenotypic diversity, and therefore niche breadth, which a population can maintain. These limits, however, are also subject to selection.
Physical Particle Representation and Generalized Transformation Theory
Authors: Prigogine I. , George Cl. , Henin F. , Mandel P. , Turner J. W.
Published: May 2006

The investigation of the recently described generalized transformation theory which leads to a non-Hamiltonian description of dynamics is pursued. The concept of generalized unitary transformations of superoperators is introduced and a specific class of transformations studied. For nondissipative systems it is equivalent to the usual unitary transformations that diagonalize the Hamiltonian. The important point is that this class of transformations remains meaningful for dissipative systems, hence a new representation of dynamics that we shall call the „physical particle” representation. It has the following properties: (
a
) The energy (or an arbitrary function of the energy) is represented by a diagonal matrix. (
b
) In the
(0)
II space (see these
Proceedings
,
65
, 789 (1970)) corresponding to the coherent processes, the evolution can be described in terms of the changes in population of the physical particles. (
c
) At thermodynamic equilibrium, the physical particles are uncorrelated and behave as independent entities; the entropy has a purely combinatorial meaning.

A full description of dynamics in this representation will be given in a forth-coming paper.
Solar Abundance of Gallium
Authors: Ross John , Aller Lawrence
Published: May 2006

The spectral region around the λ4172 Å resonance line of gallium has been synthesized at disk positions μ = 1.0, 0.5, and 0.3. The center-limb variation can be reproduced by Elste's semiempirical model if a macroturbulent smearing of the emergent spectrum due to mass motions with mean velocity decreasing with altitude are introduced. The abundance of Ga derived from disk position μ = 1 is found to be log [N(Ga)/N(H)] + 12 = 2.80.
COMPONENTS OF HISTIDINE TRANSPORT: HISTIDINE-BINDING PROTEINS AND
hisP
PROTEIN
Authors: Ames Giovanna Ferro-Luzzi , Lever Julia
Published: May 2006

The high-affinity (

K
m

= 3 × 10
-8
M) transport system for histidine in
Salmonella typhimurium
has been resolved into three components: J, K, and P. J, which is a histidine-binding protein released by osmotic shock, is specified by the
hisJ
gene:
hisJ
mutants lack the binding protein and are defective in histidine transport. Another class of mutants—
dhuA
, which is closely linked to
hisJ
—has five times the normal level of binding protein and has an increased rate of histidine transport. P, which is a protein specified by the
hisP
gene, is required for J binding protein to be operative in transport.
hisP
mutants, though defective in transport, have normal levels of J binding protein. K, a third transport component, works in parallel to J, and also requires the P protein in order to be operative in transport. A second histidine-binding protein has been found but its relation to K is unclear.
hisJ, dhuA,
and
hisP
have been mapped and are in a cluster (near
purF
) on the
S. typhimurium
chromosome.
A FURTHER ASSESSMENT OF THE ROLE OF FOUNDER EFFECTS IN THE OUTCOME OF
Tribolium
COMPETITION EXPERIMENTS
Authors: Dawson Peter S.
Published: May 2006

A novel experimental design was employed to further investigate the importance of founder effects in determining the outcome of competition between the flour beetles
Tribolium castaneum
and
T. confusum
. Each of 10 replicate cultures in seven competition series was started with 10 pairs of adults of each species that were, in turn, the progeny of 1, 2, 4, 8, 16, 32, or 64 pairs of adults, respectively, from the foundation population. Thus the founder effect occurred one generation prior to the initiation of competition. An analysis of variability among replicate cultures for the first eight monthly censuses showed a significant increase in variation with smaller numbers of original pairs, confirming the hypothesis previously proposed to explain the indeterminate outcome of replicate competition cultures initiated with small numbers of founders. In addition, there was a significant reduction in the rate of elimination of
T. confusum
with smaller numbers of original pairs. It is suggested that
T. castaneum
is more sensitive to inbreeding, and that the differential response of the two populations to inbreeding reflects a difference in their homeostatic properties.
ACCELERATION BY THYMOSIN OF THE DEVELOPMENT OF RESISTANCE TO MURINE SARCOMA VIRUS-INDUCED TUMOR IN MICE
Authors: Zisblatt Martin , Goldstein Allan L. , Lilly Frank , White Abraham
Published: May 2006

The development of resistance to progressive tumor growth and the effect of a thymic extract upon this developmental process were examined in CBA/Wh mice. Inoculating mice of various ages with murine sarcoma virus (Moloney) permitted the assessment of the period of time postnatally at which the animals developed a threshold level of resistance to progressive tumor growth. Resistance in CBA/Wh mice, at the virus dose used, was first detected at approximately two weeks of age and was completely developed at five weeks.

Thymosin, a soluble calf thymic fraction, when administered to neonatal mice beginning on the second day of life, significantly accelerated the rate of development of resistance to progressive tumor growth. The data suggest a humoral role for the thymus in the development of tumor immunity, and that the normal development of cell-mediated immunological competence can be accelerated through the use of thymus-derived extracts.
Epidermal Growth Factor: High and Low Molecular Weight Forms
Authors: Taylor John M. , Cohen Stanley , Mitchell William M.
Published: May 2006

In crude homogenates of the submaxillary gland of the male mouse, epidermal growth factor (EGF) activity was found almost entirely in a high molecular weight complex (about 74,000 daltons). This high molecular weight form may be reversibly dissociated into EGF and an EGF-binding protein. EGF was found to have a molecular weight of approximately 6400. The EGF-binding protein has a molecular weight of 29,000, and shows arginyl-esterase activity.
Electron Paramagnetic Resonance Study of the High- and Low-Spin Forms of Cytochrome P-450 in Liver and in Liver Microsomes from a Methylcholanthrene-Treated Rabbit
Authors: Peisach J. , Blumberg W. E.
Published: May 2006

The high- and low-spin forms of cytochrome P-450 were observed by electron paramagnetic resonance (epr) in a liver slice and in hepatic microsomes from a rabbit injected with methylcholanthrene. Quantitation of the epr absorption of these two chemical species and comparison with a preparation from a control rabbit showed that the single injection of drug increased the concentration of cytochrome P-450 to more than ten times its control value. Analysis of the epr spectrum for the high-spin compound showed that it is the most rhombically distorted ferric heme iron site yet observed (E/D = 0.10). It is suggested that microsomal cytochrome P-450 can exist in two interconvertible forms, in which the heme iron can either be high-spin or low-spin, depending upon the nature of the nonporphyrin ligands of the metal. There seems to be no need to postulate the existence of two different cytochrome P-450 proteins.
Specific Aggregation of SV40-Transformed Cells by Ornithine, Leucine Copolymers
Authors: Duksin Dan , Katchalski Ephraim , Sachs Leo
Published: May 2006

A basic copolymer of ornithine and leucine (1:1) was shown to rapidly agglutinate, in the absence of serum, normal cells and cells transformed by viral and nonviral carcinogens. This agglutination was inhibited by addition of serum. In presence of serum, the same copolymer and those of ornithine and valine (1:1) and arginine and leucine (1:1), produced a specific aggregation of simian virus 40 (SV40)-transformed cells cultured for about 24 hr after addition of the peptide. The rapid agglutination and SV40-specific aggregation could not be inhibited by a variety of individual amino acids or carbohydrates. The specific aggregation could be detected in mixtures of SV40-transformed and other cells, and it was not prevented by x-irradiating the cells with 4000 R. Aggregation of the SV40-transformed cells was inhibited by acidic polyamino acids provided these were added not later than about 5 hr after addition of the basic copolymer. The results indicate that the basic copolymer, in the presence of serum, produces a change in SV40-transformed cells, presumably in the surface membrane, that causes the cells to aggregate. In addition to the aggregation of cells transformed by SV40, cells transformed by adenovirus 12, which did not contain detectable SV40-specific nuclear tumor (T) antigen, were also aggregated by the basic copolymer in the presence of serum. This indicates that the ornithine, leucine copolymer is able to detect an SV40-like change in the surface membrane of cells transformed by adenovirus 12.
The Reovirus Replicative Cycle: Conservation of Parental RNA and Protein
Authors: Silverstein Samuel C. , Schonberg Michael , Levin Daniel H. , Acs George
Published: May 2006

The fate of parental reovirions in the viral replicative cycle has been analyzed using CsCl density centrifugation. After penetration of L-cells, reovirus is converted from a particle of density 1.39 g/cm
3
to a subviral particle of density 1.41 g/cm
3
. This alteration in density is temporally correlated with the hydrolysis of viral coat proteins and is qualitatively similar when particles are labeled in their RNA or protein. Ten hours after infection, when synthesis of progeny virus is underway, the parental RNA and protein are again found at density 1.39 g/cm
3
. These data demonstrate conservation of the parental RNA and protein in the subviral particle throughout the replicative cycle.
Chromosomal Distribution of Rapidly Reannealing DNA in
Drosophila melanogaster
Authors: Rae Peter M. M.
Published: May 2006

Cytological hybridization has been used to localize fractions of rapidly reannealing DNA in salivary chromosomes of
Drosophila melanogaster
. Complementary RNA of high specific activity was transcribed from hydroxyapatite-fractionated rapidly reannealing sequences and from selected buoyant-density fractions of total DNA. It was then hybridized to chromosome squashes after denaturation of DNA in NaOH. Highly „repeated” DNA sequences were detected over much of the chromosome, but were concentrated in chromocentric heterochromatin. A family of sequences with a low percentage of guanosine plus cytidine was highly concentrated in a particular region within the chromo-center. One „euchromatic” region near the tip of chromosome arm 3L also exhibited a concentration of repeated sequences.
Conformational Model of Active Transport
Authors: Young John H. , Blondin George A. , Vanderkooi G. , Green D. E.
Published: May 2006

A model of active transport of monovalent cations in mitochondria is developed. The model is based on the coupling of electron transfer to the generation of a metastable protein conformation which in turn leads to the generation of an asymmetric surface charge, a membrane potential, and a redistribution of diffusible ions across the inner mitochondrial membrane. The ions at all times move spontaneously down an electrochemical potential gradient in this model so that there is no need to invoke the concept of an ion pump. It is shown that a wide variety of experimental facts can be rationalized in terms of the present model.
Evidence for a DNA Replicative Genome for RNA-Containing Tumor Viruses
Authors: Bader John P. , Bader Artrice V.
Published: May 2006

The requirement for DNA synthesis in the reproduction of RNA tumor viruses was examined using 5-bromodeoxyuridine (BrdU). Addition of BrdU for the first 12 hr after exposure of cells to Rous sarcoma virus resulted in a large decrease in infectious progeny. However, incorporation of [
3
H]uridine into the viral RNA of virions was unaffected. Also, the numbers of virions visualized by electron microscopy were similar in BrdU-treated and untreated samples. Viral group-specific antigen was synthesized after BrdU treatment, and BrdU had little effect on transformation of cells by Rous sarcoma virus. The results support the hypothesis that the replicative genome of RNA-containing tumor viruses contains DNA.
Interallelic Complementation in Hybrid Cells Derived from Human Diploid Strains Deficient in Galactose-1-Phosphate Uridyl Transferase Activity
Authors: Nadler Henry L. , Chacko Claramma M. , Rachmeler Martin
Published: May 2006

Galactose-1-phosphate uridyl transferase activity has been demonstrated in hybrid cells formed from the fusion of human diploid fibroblasts obtained from different patients with galactosemia. The enzyme produced by the hybrid cells was similar to the normal enzyme in regard to

K
m

, pH optimum, and electrophoretic mobility on starch gel, but differed in specific activity,
V
max
and thermal stability. This is the first reported example of interallelic complementation in fused human diploid cells.
Conformational Significance of the Intrachain Disulfide Linkages in Immunoglobulins
Authors: Litman G. W. , Good R. A. , Frommel D. , Rosenberg A.
Published: May 2006

Biophysical studies of intact immunoglobulins, enzymatically derived immunoglobulin subunits, and chemically derived immunoglobulin chains are reported. All the forms studied lacked optical activity associated with the α-helix conformation. A dichroism band centered near 217 nm, which has been assigned to the β-sheet conformation, was present in all subunits that contained at least two covalently linked intrachain disulfide loop regions. This dichroism band could not be detected in Component II, the C-terminal 120 amino acids of the heavy chain. The reduction and alkylation of the intrachain disulfide linkages caused a large conformational change associated with short range interactions. The cleavage of the intrachain disulfide also produced a large change in the environment of two aromatic amino acids, tyrosine and tryptophan. These observations indicate some unique conformational relationships for immunoglobins which may be related to the functional demands placed on this class of macromolecule.
The Total Amino Acid Content of Fossil Pecten Shells
Authors: Akiyama Masahiko , Wyckoff Ralph W. G.
Published: May 2006

Amino acid analyses have been made of the insoluble protein, soluble peptide, and free amino acid fractions isolated from a series of fossil pecten shells of ages from the Pleistocene through the Jurassic.

The total amino acid content declines progressively with age of the fossil but, in contrast to oyster shells, only a small fraction of the initial protein is present in the Pleistocene and older specimens. Though the thermally less stable acids are depleted in the free acid fraction, this is not true for the insoluble proteins and peptides. Large amounts of free amino acids and peptides persist through the Pliocene, considerable quantities of peptide have been recovered from the Miocene specimens, and even the oldest fossils have retained analyzable amounts of all three fractions.
Use of a Snake Venom Toxin to Characterize the Cholinergic Receptor Protein
Authors: Changeux Jean-Pierre , Kasai Michiki , Lee Chen-Yuan
Published: May 2006

α-Bungarotoxin, a polypeptide of mol wt 8000 purified from the venom of
Bungarus multicinctus
, blocks irreversibly and specifically the excitation by cholinergic agonists on the isolated electroplax and on purified membrane fragments
in vitro
. The toxin also blocks the
in vitro
binding of decamethonium to a protein recently isolated from electric tissue. This observation strengthens our earlier conclusion that this protein is the cholinergic receptor macromolecule.
Revised Identification of the Chromophore of a Cell Division Factor from Crown Gall Tumor Cells of
Vinca rosea
L
Authors: Wood Henry N.
Published: May 2006

Low-resolution mass spectrometry, UV spectra in acid, neutral, and alkaline solution, and nuclear magnetic resonance indicated that the chromophore of one member of a new class of cell division-promoting factors isolated from crown gall tumor tissues consisted of a 3,7-alkyl-2-alkylthio-6-purinone with one free proton in the ring. Glucose constitutes the sugar moiety.
Binding of Polycyclic Aromatic Hydrocarbons to Polyadenylic Acid
Authors: Craig A. Morrie , Isenberg I.
Published: May 2006

A number of polycyclic aromatic hydrocarbons bind to the double-stranded, acid form of polyadenylic acid (poly A). Model building shows that these hydrocarbons may intercalate in the helix, and be well protected from contact with the aqueous medium. Hydrocarbons that are too large to be so protected are found not to bind. A size criterion for the binding of hydrocarbons to poly A therefore exists. This criterion differs from one that was previously found for DNA. The size criteria for DNA and poly A, together, serve as strong evidence for the intercalation model for hydrocarbon complexes.

Model-building experiments show that only a small portion of the hydrocarbon need extend into the medium to prevent binding. This finding implies that in two cases (1,2,5,6-dibenzanthracene·poly A and 3,4-benzpyrene·DNA) the structure of the complex is almost completely determined by the size criterion alone.
Enzymatic Carboxylation of Biotin: Molecular and Catalytic Properties of a Component Enzyme of Acetyl CoA Carboxylase
Authors: Dimroth Peter , Guchhait Ras B. , Stoll Erwin , Lane M. Daniel
Published: May 2006

The biotin carboxylase component of acetyl CoA carboxylase has been purified approximately 2000 times from
Escherichia coli
. This protein, which catalyzes the carboxylation of free
d
-biotin, is free of the biotin-containing carboxyl carrier protein, is homogeneous by polyacrylamide gel electrophoresis and analytical ultracentrifugation, and has been crystallized. Biotin carboxylase, with a molecular weight of approximately 100,000, is composed of two 50,000-dalton subunits. The catalytic capacity of biotin carboxylase is markedly enhanced by ethanol (11 times at 15% v/v), and certain other organic solvents; this may mimic an effector-mediated response. The kinetic effect is exclusively on the maximal velocity of the reaction. Activation by ethanol is reversible and not accompanied by aggregation or disaggregation of the enzyme.
Mechanism of Carcinogenesis by RNA Tumor Viruses, III Formation of RNA·DNA Complex and Duplex DNA Molecules by the DNA Polymerase(s) of Avian Myeloblastosis Virus
Authors: Fujinaga Kei , Parsons J. Thomas , Beard J. W. , Beard Dorothy , Green Maurice
Published: May 2006

DNA polymerase activity can be unmasked in avian myeloblastosis virus (AMV) by treatment with the nonionic detergent Nonidet P-40. Two products are formed: (1) RNA·DNA hybrid molecules and (2) duplex DNA molecules. The kinetics of dTTP incorporation into DNA are biphasic: an initial rapid reaction for 4 min at 37°C with a minimal polymerization rate of 10-20 nucleotides per see, and a second reaction at about half the initial rate. Viral RNA·DNA complexes are detected as early as 30 sec after the initiation of DNA synthesis; DNA free of template is formed subsequently. Most of the free AMV DNA forms an RNA·DNA hybrid when annealed with viral RNA. Over half of the free AMV DNA product is inferred to be double-stranded, since it is retained on hydroxyapatite columns after elution with 0.12 M phosphate buffer, and is resistant to
Escherichia coli
exonuclease I. Adenovirus or calfthymus DNA added to unmasked AMV stimulates DNA synthesis 4-16 times if there is no treatment with RNase, and 40-130 fold if RNase treatment precedes the enzyme assay. It is possible that two polymerases are present, or that a single enzyme forms both the RNA·DNA hybrid and the double-stranded product.
In Vitro
Induction of Granulocyte Differentiation in Hematopoietic Cells from Leukemic and Non-Leukemic Patients
Authors: Paran Michael , Sachs Leo , Barak Yigal , Resnitzky Peretz
Published: May 2006

Human spleen-conditioned medium can induce the formation
in vitro
of large granulocyte colonies from normal human bone marrow cells. The granulocyte colonies contained cells in various stages of differentiation, from myeloblasts to mature neutrophile granulocytes. Human spleen-conditioned medium also induced colony formation with rodent bone-marrow cells, whereas rodent spleen-conditioned medium induced colony formation with rodent bone marrow but not with human cells.

This
in vitro
system has been used to determine the potentialities for cell differentiation in bone-marrow and peripheral blood cells from patients with a block in granulocyte differentiation
in vivo
. The cloning efficiency, colony size, and number of mature granulocytes in bone-marrow colonies from patients with congential neutropenia, whose bone marrow contained only 1% mature granulocytes, were not less than in people whose bone marrow had the normal level of about 40% mature granulocytes. The cloning efficiency of peripheral blood cells from patients with acute myeloid leukemia was 350 times higher, with 10 times larger colonies, than the cloning efficiency of peripheral blood cells from normal people. The cytochemical properties and number of mature granulocytes in colonies from the leukemic patients were the same as in colonies from non-leukemic people.

The results indicate that a block in cell differentiation
in vivo
, in these cases with neutropenia and acute myeloid leukemia, was overcome
in vitro
, in the presence of an inducer in the conditioned medium. In patients with chronic myeloid leukemia, colony formation was induced only in some of the cases. This indicates that there are blast cells with different potentialities for the development of colonies in different patients.
Recovery of a New Virus from Apparently Normal Chick Cells by Infection with Avian Tumor Viruses
Authors: Hanafusa T. , Hanafusa H. , Miyamoto T.
Published: May 2006

Cells derived from the majority of chick embryos, although free of presently known avian tumor virus particles, appear to contain genetic materials similar to those found in this virus group. After infection of these cells with avian leukosis or Rous sarcoma virus, the genetic factor was recovered by incorporation into mature infectious virus. The newly isolated virus (RAV-60) did not require the assistance of another virus for its replication. The virus had most of the attributes of an RNA-containing avian leukosis virus, and its outer structure resembled the Rous sarcoma virus known as RSV(0).
Leukemia Virus Activation in Chronic Allogeneic Disease
Authors: Hirsch M. S. , Black P. H. , Tracy G. S. , Leibowitz S. , Schwartz R. S.
Published: May 2006

Young adult (BALB/c × A/J)F
1
hybrid mice have no detectable leukemia viruses. When inoculated with parental BALB/c spleen lymphoid cells, also free of detectable virus, leukemia viruses rapidly become activated in the injected host. Because of similarities between such graft-induced allogeneic disease and spontaneous autoimmunity, it is proposed that autoimmune reactions may activate latent viruses.
Uptake of Transfer Ribonucleic Acid by Normal and Leukemic Cells
Authors: Herrera Flor , Adamson Richard H. , Gallo Robert C.
Published: May 2006

Uptake of tRNA (
Escherichia coli
) was demonstrated in the murine leukemia, L1210 and in a human lymphoblast (NC-37) cell lines. In both cell lines, uptake of tRNA was rapid, reaching a maximum within 45 sec, and was linear with concentration up to about 50 μg/ml. This uptake of exogenous tRNA apparently was not due to altered membrane permeability or impaired cell viability, nor to ribonuclease degradation of the macromolecule. Furthermore, about 20% of the tRNA taken up by the cells remains functional and apparently intact. This was demonstrated by: (
a
) acylation with
E. coli
aminoacyl-tRNA synthetases; (
b
) methylation with leukemic cell tRNA-methylases, and (
c
) demonstrating
14
C-labeled 4S RNA in the cytoplasmic fraction of the leukemic cells after the addition of
E. coli
[
14
C]tRNA. The results demonstrate that tRNA can enter mammalian cells and suggest that an energy independent, carrier-mediated, mechanism may be operative.
Neurotransmitter-Specific Synaptosomes in Rat Corpus Striatum: Morphological Variations
*
Authors: Gfeller Eduard , Kuhar Michael J. , Snyder Solomon H.
Published: May 2006

This communication describes ultrastructural variations among synaptosomal fractions isolated from the corpus striatum of the rat by incomplete equilibrium sedimentation in sucrose density gradients, and attempts to relate the variations to neurotransmitter-specific synaptosomes. The concentration of synaptosomes in each fraction of the density gradient was found to be correlated with the concentration of potassium, a marker for cytoplasm occluded within synaptosomes. Monoamine oxidase activity was found to be correlated with the incidence of free mitochondria in the gradients.

Synaptosomes from denser gradient fractions showed a markedly increased frequency of adherent postsynaptic elements and intraterminal mitochondria. These denser gradient fractions were rich in synaptosomes containing norepinephrine, dopamine, serotonin, and acetylcholine, while synaptosomes in lighter portions of the gradients were rich in γ-aminobutyric acid and other amino acids. These data suggest that significant morphological variations may exist among different neurotransmitter-specific nerve terminals in the brain.
N-Terminal Amino-Acid Sequence of African Lungfish Immunoglobulin Light Chains
Authors: Litman G. W. , Wang A. C. , Fudenberg H. H. , Good R. A.
Published: May 2006

The sequence of the N-terminal ten amino acids of the unblocked light chains derived from the low molecular weight immunoglobulin of a dipnoid fish, the African lungfish (
Protopterus aethiopicus
), has been determined. A degree of sequence heterogeneity as extensive as that displayed by pooled mammalian light chains was encountered. The major N-terminal sequence of the amino acids of light chains from lungfish immunoglobins can be made homologous with that of various Elasmobranchean, Chondrostean, Avian, and Mammalian species if an internal deletion of two base triplets in the gene coding for light chains from lungfish immunoglobulins is assumed. The existence of a deletion and/or insertion mechanism may have profound biological significance, since it would be ideal for the introduction of variability into immunoglobulin chains without sacrificing certain integral features of the antibody molecule.
Chlorpromazie and Dopamine: Conformational Similarities that Correlate with the Antischizophrenic Activity of Phenothiazine Drugs
Authors: Horn Alan S. , Snyder Solomon H.
Published: May 2006

Phenothiazines and butyrophenones are known to alter dopamine (3,4-dihydroxyphenethylamine) metabolism in the brain in a fashion suggesting that they may block dopamine receptors. We observed, using Dreiding molecular models, that dopamine in its solid-state conformation is superimposable upon a portion of the known x-ray structure of chlorpromazine [2-chloro-10-(3-dimethylaminopropyl)-phenothiazine]. The ability of phenothiazine drugs to mimic the dopamine-like conformation correlates with their antischizophrenic efficacy. These structure-activity relationships explain the importance of a substituent in ring
a
, a three-carbon side chain bearing the amino group, and a hetero atom between rings
a
and
c
.