bluuebunny/crossref_metadata_2025 huggingface dataset:
Parathyroid Hormone: Secretion and Metabolism
In Vivo
Authors: Habener Joel F. , Powell David , Murray Timothy M. , Mayer G. P. , Potts John T.
Published: May 2006

Gel filtration and radioimmunoassay were used to determine the molecular size and immunochemical reactivity of parathyroid hormone present in gland extracts, in the general peripheral circulation, and in parathyroid effluent blood (obtained by venous catheterization) from patients with hyperparathyroidism, as well as from calves and from cattle. Hormone secreted
in vivo
from normal bovine parathyroid glands and from human parathyroid adenomas is similar in size to the 84-amino-acid peptide (molecular weight of 9500) extracted from the parathyroids. However, much of the immunoreactive parathyroid hormone present in the peripheral circulation of man and cattle is smaller than the extracted or secreted hormone; it elutes from gel columns at a position corresponding to a molecular weight of about 7000. The immunological characteristics of extracted and secreted hormone are identical, while hormone in the general circulation is immunologically dissimilar to extracted and secreted hormone. The results indicate that parathyroid hormone secreted from the parathyroids in man and cattle is at least as large as the molecule extracted from normal bovine glands. However, once secreted into the circulation the hormone is cleaved, and one or more fragments, immunologically dissimilar to the originally secreted hormone, constitute the dominant form of circulating immunoreactive hormone.
Comparative Immunology of Algal Biliproteins
Authors: Glazer A. N. , Cohen-Bazire Germaine , Stanier R. Y.
Published: May 2006

The three spectroscopically distinct classes of phycobiliproteins characteristic of the Cyanophyta and Rhodophyta—phycocyanins, allophycocyanins, and phycoerythrins—share no common antigenic determinants detectable by the Ouchterlony double diffusion technique. Each class of phycobiliprotein, from both Cyanophyta and Rhodophyta, possesses a strong determinant common to all members of that class. With respect to an antiserum directed against a specific cyanophytan biliprotein, all heterologous biliproteins of the same class are immunologically identical, as shown by the fact that absorption with a given heterologous antigen simultaneously eliminates crossreactions with other heterologous antigens. A cryptophytan phycoerythrin was found to be immunologically unrelated to any of the cyanophytan or rhodophytan biliproteins examined.
DNA Polymerases of Tumor Virus: Specific Effect of Ethidium Bromide on the Use of Different Synthetic Templates
Authors: Fridlender B. , Weissbach A.
Published: May 2006

The DNA polymerase enzymes from avian, murine, and feline RNA tumor viruses can be distinguished by their ability to read specific, synthetic primertemplates. The copying of templates containing adenylic and thymidylic acids by all these DNA polymerases is inhibited by ethidium bromide, though this compound affects the polymerases from mammalian tumor viruses much more than the enzyme from avian tumor viruses. Conversely, ethidium bromide stimulates the ability of the enzymes from avian tumor viruses to use primertemplates containing only guanylic and cytidylic acids, whereas the mammalian tumor virus enzymes are moderately inhibited.
Synaptogenesis in Reaggregating Brain Cell Culture
Authors: Seeds Nicholas W. , Vatter Albert E.
Published: May 2006

Dissociated cells from embryonic mouse brain reassociate in rotation culture to form highly organized aggregates. Electron microscopic observations of aggregates show the presence of synapses that mature and increase in number during culture. Apparent myelination of axons is observed in the aggregates after 5 weeks of culture. Thus, brain cell aggregates perform two highly specialized morphological events that are characteristic of mouse brain differentiation.
Mechanism of Action of Thrombin on Fibrinogen, I. Synthesis of Fibrinogen-like Peptides, and Their Proteolysis by Thrombin and Trypsin
Authors: Andreatta Rudolf H. , Liem Ronald K. H. , Scheraga Harold A.
Published: May 2006

In a study of the action of thrombin on fibrinogen and a comparison of this enzyme with trypsin, several fibrinogen-like oligopeptides were synthesized. The hydrolysis of the arginyl-glycine bond in these peptides, by both of these enzymes, is examined and compared.
Uptake of Heterologous Genome by Mammalian Spermatozoa and Its Transfer to Ova through Fertilization
Authors: Brackett B. G. , Baranska W. , Sawicki W. , Koprowski H.
Published: May 2006

Simian virus 40 (SV40) adsorbs on rabbit spermatozoa but does not penetrate the cells, as indicated by the absence of radioactive material seen on autoradiography of spermatozoa exposed to [
3
H]thymidine-labeled SV40. In contrast, after exposure of spermatozoa to labeled SV40 DNA, radioactive material was found in the postacrosomal area of the spermatozoa. Furthermore, when spermatozoa exposed to SV40 DNA were fused with cells of the CV-1 line of African green monkey kidney cells, infectious SV40 was isolated. After uterine insemination of rabbits with spermatozoa infected with SV40 DNA, both unfertilized and one- and two-celled fertilized ova were obtained. When the fertilized ova were cocultivated with CV-1 cells, infectious virus was recovered. In contrast, CV-1 cells exposed to the unfertilized ova or to zonae pellucidae or polar bodies from the fertilized ova did not show a cytopathic effect. This report provides the first evidence that a heterologous genome can be incorporated into a mammalian spermatozoon and subsequently carried into an ovum during the process of fertilization.
Dissociation of Mammalian Polyribosomes into Subunits by Puromycin
Authors: Blobel Günter , Sabatini David
Published: May 2006

Hepatic ribosomes have been dissociated into biologically active subunits as follows. Polysomes were treated at 0°C with puromycin at high ionic strength. This released most of the nascent polypeptide chains without dissociating the polysomes, which retained the mRNA and the tRNA moiety of peptidyl tRNA, but were unable to continue the translation of mRNA. The polysomes were then heated to 37°C, when they dissociated completely into subunits. Similar treatment without puromycin resulted in only partial dissociation.
Drastic Alteration of Ribosomal RNA and Ribosomal Proteins in Showdomycin-Resistant
Escherichia coli
Authors: Beljanski Mirko , Bourgarel Pierre , Beljanski Monique
Published: May 2006

In a mutant of
Escherichia coli
resistant to showdomycin, both the 50S and 30S ribosomal subunits contain RNA species in which the purine concentration greatly exceeds that of pyrimidines. The same is true for total rapidly-labeled RNA. The modified ribosomal RNA hybridizes poorly with homologous DNA, which is apparently unchanged in base composition. Acrylamide gel electrophoresis of mutant ribosomal proteins shows a highly altered protein pattern for both ribosomal subunits, although the activity of these ribosomes is not decreased.
Asynchronous Synthesis of the Complementary Strands of the Reovirus Genome
Authors: Schonberg Michael , Silverstein Samuel C. , Levin Daniel H. , Acs George
Published: May 2006

The mechanism of replication of the double-stranded RNA genome of reovirus has been analyzed by tracing the fate of the parental double-stranded RNA genome and by determining whether the complementary strands, which comprise the progeny double-stranded RNA, are synthesized simultaneously or sequentially. The results indicate that the parental double-stranded RNA is conserved as the original duplex molecule within a subviral particle throughout the viral replicative cycle. The complementary strands, which form the progeny double-stranded RNA, are produced asynchronously. Minus strands are synthesized on preformed plus-strand templates, whereas plus strands appear to be synthesized on double-stranded RNA templates.
The Leader Sequence from the 5′-Terminus to the A-Protein Initiation Codon in MS2-Virus RNA
Authors: Wachter R. De , Vandenberghe A. , Merregaert J. , Contreras R. , Fiers W.
Published: May 2006

RNA fragments of different chain length, each containing the 5′-terminal guanosine tetraphosphate (pppGp) of bacteriophage-MS2 RNA, have been isolated from partial ribonuclease digests of the viral RNA. The longest fragment overlaps with the ribosomalbinding site of the A-protein cistron. The base sequence has been established for the major part. The results directly confirm that the A-protein cistron is closest to the 5′-terminus. Its initiating (AUG) codon starts at position 130, being preceded by an untranslated sequence of 129 nucleotides.
Energy Transfer in Rhodopsin,
N
-Retinyl-Opsin, and Rod Outer Segments
Authors: Ebrey Thomas G.
Published: May 2006

N
-retinyl, the chromophore of bleached and reduced rhodopsin,
N
-retinyl-opsin, was used as a covalently attached fluorescence probe to examine the structure of
N
-retinyl-opsin and the rod outer segment. The efficiency of energy transfer from the protein part of
N
-retinyl-opsin to the chromophore is 12 ± 5%. It is argued that this implies that the
N
-retinyl-opsin molecule is asymmetrical. Kropf has estimated the efficiency of energy transfer from the protein to the chromophore in native rhodopsin to be about 50%. This difference of efficiencies seems to imply a large movement of the chromophore away from the tryptophans of the opsin after rhodopsin is bleached.

From excitation spectrum measurements, it has been found that light absorbed by the protein of the rod outer segments has more action in sensitizing the fluorescence of the chromophore than does light absorbed by the protein part of pure
N
-retinyl-opsin. Thus, some other tryptophans or tyrosines in either another
N
-retinyl-opsin molecule or another protein must be close enough (about 28 Å) to the chromophore to transfer energy to it. Measurements of the polarization of the fluorescence of the chromophore suggest, however, that the chromophores of neighboring
N
-retinyl-opsin molecules are more than 20 Å apart. Moreover, these neighboring chromophores do not transfer energy to each other, tending to rule out any clustering of chromophores of different
N
-retinyl-opsin molecules and suggesting that rhodopsin chromophores do not transfer energy to each other.
Further Characterization of the Cellular DNA Hybridizing with the RNA of Rous Sarcoma Virus
Authors: Yoshikawa-Fukada M. , Ebert J. D.
Published: May 2006

Both 70S and 4S RNAs of Rous sarcoma virus (RSV) contain nucleotide sequences homologous to those in cellular DNA. Preparations of these RNAs were found to include some adventitious cellular sRNA. Nevertheless, both 70S and 4S RSV-RNAs were found by competition techniques to contain sequences distinct from those in cellular ribosomal RNA and 4S RNA. Competition experiments also reveal substantial homology between 70S and 4SRSV-RNA. In hybridization experiments performed in formamide at low temperatures, the melting profiles of hybrids between 70S RSV-RNA and cellular DNA, and 4S RSV-RNA and cellular DNA, are essentially superimposable. It is suggested that there are at least two origins of 4S RSV-RNA in RSV-RNA preparations: degradation of 70S RSV-RNA and inclusion of adventitious cellular 4S RNA. The possibility of a specific viral 4S RNA is not excluded.
Fate of Transforming DNA After Uptake by Competent
Bacillus subtilis
: Failure of Donor DNA to Replicate in a Recombination-Deficient Recipient
Authors: Davidoff-Abelson Rosa , Dubnau David
Published: May 2006

The fate of radioactively-labeled transforming DNA was studied in a recombination-deficient strain of
Bacillus subtilis
that carried the
recB2
mutation (Rec
-
) and was sensitive to radiation. Experiments performed with extracts of this strain after transformation showed that the recovery of donor transforming activity and the appearance of recombinant transforming activity occurred to the same extent as in the Rec
+
strain. Sucrose gradient analyses revealed that donor-recipient complex is also formed to the same extent in the Rec
-
and Rec
+
strains, but that 80-90% of the donor genetic material in the complex failed to replicate in the Rec
-
mutant.
Double-Stranded Poliovirus RNA Inhibits Initiation of Protein Synthesis by Reticulocyte Lysates
Authors: Ehrenfeld E. , Hunt Tim
Published: May 2006

Infection of HeLa cells with poliovirus results in an inhibition of host-cell protein synthesis. Cytoplasmic extracts from infected cells contian an activity that inhibits initiation of protein synthesis
in vitro
by rabbit reticulocyte lysates. This inhibitory activity has been purified and characterized, and is shown to reside in poliovirus double-stranded RNA. The intact double-stranded molecule is not essential for inhibitory activity.
Mucopolysaccharide and Protein—Polysaccharide of a Transplantable Rat Chondrosarcoma
Authors: Choi Haing Ug , Meyer Karl , Swarm Richard
Published: May 2006

Two mucopolysaccharides, chondroitin 4-sulfate (97.8%) and hyaluronic acid (1.2%), were isolated after exhaustive proteolysis of a transplantable chondrosarcoma of the rat. The chondroitin 4-sulfate was fractionated into three fractions of varying degrees of sulfation and chain length. Keratan sulfate and chondroitin 6-sulfate were absent. Extraction of the fresh tumor gave two protein—polysaccharides of similar carbohydrate composition, one soluble in 0.5 M NaCl, the other insoluble. The latter was solubilized in 4 M guanidine·HCl. A dialyzable fraction from the 4 M guanidine solution may be responsible for the insolubility. Both protein—polysaccharides were antigenic and cross-reacted with similar fractions of bovine and human cartilage.
The Reaction of Glucagon with Its Receptor: Evidence for Discrete Regions of Activity and Binding in the Glucagon Molecule
Authors: Rodbell Martin , Birnbaumer Lutz , Pohl Stephen L. , Sundby F.
Published: May 2006

Des-histidine-glucagon (DH-glucagon, glucagon
2-29
) does not activate the glucagon-sensitive adenylate cyclase system present in either liver plasma membranes or in fat-cell “ghosts”, but inhibits the response of these systems to submaximal concentrations of glucagon. DH-glucagon also inhibits, competitively, the binding of [
125
I]glucagon to its receptor in liver plasma membranes. Amino-terminal fragments of glucagon (glucagon
1-21
, glucagon
1-23
) and carboxy-terminal fragments (glucagon
20-29
, glucagon
22-29
) failed to activate adenylate cyclase, to inhibit the response of the enzyme to glucagon, or to compete with labeled glucagon at its receptor.

It is concluded that the amino-terminal histidine residue of glucagon is essential for biological activity and that a hydrophobic near-carboxy-terminal region (residues 22-27) is essential for binding of glucagon to its receptor. Amino-terminal histidine may also contribute to the binding of glucagon, since the apparent affinity of DH-glucagon for the receptor is only about one-sixth that of glucagon. Thus, essentially the entire molecule of glucagon must be considered to be the biologically active species.

Because, as shown elsewhere, the binding of glucagon to its receptor shows characteristics of hydrophobic bonding, and because certain detergents induce conformational changes in the carboxy-terminal binding region of glucagon, the binding is probably of a lipophilic type.
Multipliers on Compact Lie Groups
Authors: Weiss Norman J.
Published: May 2006

Sufficient conditions are found for a biinvariant operator on a compact Lie group to be bounded on

L
p

, 1 <
p
< ∞. The proof uses properties of
g
-functions on such a group, and an analog to the familiar relationship between differentiation and multiplication under the Fourier transform.
Specific Cytoplasmic Glucocorticoid Hormone Receptors in Hepatoma Tissue Culture Cells
Authors: Baxter John D. , Tomkins Gordon M.
Published: May 2006

Kinetic and equilibrium studies are presented for the reversible binding of [
3
H]dexamethasone by “specific” macromolecular receptors in the cytoplasmic fraction of cultured rat hepatoma cells. As in the case of the nuclear receptors in the same cells, the binding affinities of various steroids for the cytoplasmic receptors are closely correlated with the activities of these compounds as inducers of both tyrosine aminotransferase (EC 2.6.1.5) and cell adhesiveness. This suggests that the binding reaction is important for the biological effects of the hormones. Steroid-binding activity is inhibited by various proteases, mercurials, and 1 M KCl, but not by DNase or RNase. The receptors sediment in sucrose gradients in 0.5 M KCl near 4S, and at lower ionic strength near 7S; some of their physical properties are altered upon binding steroid. Bound dexamethasone can be recovered from the receptors as the unaltered steroid.
Induction of Cytokinin-Independent Tobacco Tissues by Substituted Fluorenes
Authors: Bednar Thomas W. , Linsmaier-Bednar Elfriede M.
Published: May 2006

Two morphactins and three aminofluorenes initiated the formation of compact tissue nodules in hormone-dependent tobacco callus cultures. These nodules, upon subculture, behaved like partially transformed plant tumors. They grew on cytokinin-free media, while control callus and nonnodule tissue still required an exogenous cytokinin source. The data indicate that substituted fluorenes, including carcinogenic aminofluorenes, can cause a neoplastic growth response in cultured tobacco tissues. Of particular interest in this study is the finding that a directed and heritable cellular change is induced in tobacco tissue in which a specific (the endogenous cytokinin) biosynthetic system is regularly and persistently activated.
A New Labor Theory of Value for Rational Planning Through Use of the Bourgeois Profit Rate
Authors: Weizsäcker C. C. Von , Samuelson Paul A.
Published: May 2006

To maximaze steady-state per capita consumptions, goods should be valued at their “synchronized labor requirement costs”, which are shown to deviate from Marx's schemata of “values” but to coincide with bourgeois prices calculated at dated labor requirements, marked-up by compound interest, at a profit or interest rate equal to the system's rate of exponential growth. With capitalists saving all their incomes for future profits, workers get all there is to get. Departures from such an exogenous, or endogenous, golden-rule state are the rule in history rather than the exception. In the case of exponential labor-augmenting change, it is shown that competitive prices will equal historically embodied labor content.
Regional Coexistence of Species and Competition between Rare Species
Authors: Levins Richard , Culver David
Published: May 2006

A model is developed for the coexistence and exclusion of species over a region of similar habitable patches. Since the balance of local extinction and colonization would leave some patches unoccupied even without competitors, species may coexist even when all the patches are the same. Regional competition coefficients are found when species affect the local extinction or migration rates of each other. Rare species can regulate each other and even exclude other species completely.
Subunit Structure of the Phycobiliproteins of Blue-Green Algae
Authors: Glazer A. N. , Cohen-Bazire Germaine
Published: May 2006

The phycobiliproteins of the blue-green algae
Synechococcus
sp. and
Aphanocapsu
sp. were characterized with respect to homogeneity, isoelectric point, and subunit composition. Each of the biliproteins consisted of two different noncovalently associated subunits, with molecular weights of about 20,000 and 16,000 for phycocyanin, 17,500 and 15,500 for allophycocyanin, and 22,000 and 20,000 for phycoerythrin. Covalently bound chromophore was associated with each subunit.
Effect of Rifampicin and Two of Its Derivatives on Cells Infected With Moloney Sarcoma Virus
Authors: Calvin Melvin , Joss Urs R. , Hackett Adeline J. , Owens Robert B.
Published: May 2006

It is shown that rifampicin, and especially the related antibiotic 2′,6′-dimethyl-
N
(4′)-benzyl-
N
(4′)- [desmethyl]rifampicin (DMB-rifampicin) can inhibit focus formation by Moloney sarcoma virus on BALB/3T3 tissue cultures. At 10 μg/ml DMB-rifampicin totally inhibits focus formation while reducing virus replication by at least a factor of fifty and cell proliferation by only a factor of three. These observations, taken together with those of others, suggest a role for an RNA-dependent DNA polymerase and the gene for its synthesis both in normal cell processes and in the transformation process.
Antibodies Reactive with Native Lysozyme Elicited by a Completely Synthetic Antigen
Authors: Arnon Ruth , Maron Elchanan , Sela Michael , Anfinsen Christian B.
Published: May 2006

A synthetic peptide consisting of the aminoacid sequence of residues 64-82 of lysozyme, with alanine replacing cysteine as residue 76, was prepared by the solid-phase technique. Mild reduction followed by reoxidation in air of the deprotected peptide led to the formation of a closed loop containing an intrachain disulfide bond. A conjugate consisting of this “loop” attached to multi-poly(DL-alanyl)-poly(L-lysine) elicited, in rabbits and goats, the formation of antibodies capable of reacting with lysozyme and with the loop peptide prepared from it. These immunological interactions can be inhibited by either lysozyme or the loop peptide, but not by the performic acid-oxidized open-chain peptide. Thus, the antibodies elicited by the completely synthetic antigen show specificity toward the “loop” structure (residues 64-80) of native lysozyme.
Bacterial Mutants Defective in Plasmid Formation: Requirement for the
lon
+
Allele
Authors: Takano Toshiya
Published: May 2006

Bacterial mutants defective in plasmid formation were selected for their inability to be transduced to chloramphenicol resistance by bacteriophage PlCM. The mutants isolated are indistinguishable from a
lon
mutant strain. Both the
lon
strain and the mutants isolated here show very poor lysogenization by P1 and very low transduction to Gal
+
by the plasmid formation of the λ
gal
8
-
Nam7am53cI
857
. The
lon
+
gene function of the host bacteria is indispensable for plasmid formation, even though P1 and λ
+
can grow normally on the
lon
strains and λ
+
can be integrated normally in
lon
as well as in the
lon
+
bacteria. Phage mutants that can persist as plasmids in
lon
strains were isolated from P1CM. The function of the
lon
+
gene is discussed with regard to plasmid formation.
Components of Adenovirus-Simian Virus 40 Hybrid Viruses
Authors: Baum Stephen G. , Fox Robert I.
Published: May 2006

The DNA and protein components of the adenovirus 7-simian virus (SV)40 hybrid virus “E46
+
” have been investigated. The Ad.7-SV40 hybrid DNA genome could be distinguished from nonhybrid Ad. 7 genome on the basis of its molecular weight in an alkaline sucrose gradient. The hybrid genome could also be separated from nonhybrid adenovirus 2 DNA when purified transcapsidant adenovirus 2
+t7
(Ad.7-SV40 DNA within an Ad.2 capsid) was studied. The presence and amount of SV40 DNA in the hybrid virus genome was determined by DNA-RNA hybridization. The results presented suggest: (
i
) that about 10% of the particles in the E46
+
preparations contained SV40 DNA covalently linked to adenovirus DNA; (
ii
) that the hybrid virus genome has a molecular weight 10-12% lower than that of nonhybrid virus, consistent with a deletion of adenovirus DNA; and (
iii
) that the hybrid virus contained only 40-50% of a total SV40 genome.

The protein components of the Ad.7-SV40 hybrid virus were examined by acrylamide gel electrophoresis in sodium dodecyl sulfate. No significant quantitative or qualitative differences between the proteins of hybrid and nonhybrid adenovirus were demonstrated.
Constitutive Mutants in a Regulatory Gene Exerting Positive Control of Quinic Acid Catabolism in
Neurospora crassa
Authors: Valone James A. , Case Mary E. , Giles Norman H.
Published: May 2006

In
Neurospora crassa
, evidence has recently been obtained for a cluster of four closely-linked genes controlling the inducible enzymes catalyzing the first three reactions in the catabolism of quinic acid. Three of these genes appear to be the structural genes for the three enzymes. The fourth gene, designated
qa-1
, has been interpreted as having a regulatory function, since
qa-1
mutants are pleiotropic types, are noninducible for the three enzymes, and form heterocaryons which complement mutants in the structural genes. The present studies were undertaken to elucidate further the nature of the regulatory role of the
qa-1
locus. A number of constitutive (
qa-1
C
) mutants have been obtained from certain
qa-1
mutants as revertants selected for their ability to grow on quinic acid as a sole source of carbon. These
qa-1
C
mutants produce high levels of all three enzymes in the absence of an inducer, map within (or very close to) the
qa-1
locus, and produce a catabolic dehydroquinase (EC 4.2.1.10) which is indistinguishable, on the basis of thermolability tests, from that of wild type. In addition, when grown in the absence of an inducer, heterocaryons between wild-type (
qa-1
+
) and different
qa-1
C
mutants exhibit markedly different levels of constitutivity (from 5 to 50% of the particular parental
qa-1
C
mutant) for catabolic dehydroquinase, one of the enzymes under
qa-1
control. These overall results are interpreted as supporting the hypothesis that the
qa-1
+
gene product (presumably a multimeric protein) plays only a positive regulatory role in initiating synthesis of the three quinate catabolic enzymes.
Laser Raman Investigation of the Effect of Cholesterol on Conformational Changes in Dipalmitoyl Lecithin Multilayers
Authors: Lippert Joseph L. , Peticolas Warner L.
Published: May 2006

Large and abrupt changes are observed at 38°C in the 1100 cm
-1
region of the Raman spectrum of aqueous dipalmitoyl lecithin multilayers. They correspond to conformational changes due to the melting of the paraffin side chains. The addition of cholesterol to the multilayers broadens but does not abolish these changes. It is suggested that the addition of cholesterol decreases the interactions between adjacent paraffin side chains of lecithin, causing a change from a cooperative to a noncooperative gel-liquid crystal transition. Removal of water from dipalmitoyl lecithin also results in a noncooperative transition strikingly similar to that caused by addition of cholesterol. Raman spectroscopy thus provides a new and sensitive probe for analyzing the structures of membranes and their constituents.
DNA Polymerase Activities and Nucleic Acid Components of Virions Isolated from a Spontaneous Mammary Carcinoma from a Rhesus Monkey
Authors: Schlom J. , Spiegelman S.
Published: May 2006

Virions isolated from a spontaneous mammary carcinoma of a rhesus monkey and propagated in human cells possess an RNA-instructed DNA polymerase. They also exhibit DNA polymerase activities that respond to either double-stranded DNA or synthetic RNA·DNA hybrid complexes as templates. The virion has been shown to have a density of 1.16 g/ml and to contain a nucleic acid species of high molecular weight (sedimentation coefficient, 60-70 S), which bands as RNA at 1.670 in a Cs
2
SO
4
equilibrium density gradient. In addition, the virions contain species of low molecular weight (4-6 S) that consist of RNA as well as components banding at densities characteristic of DNA·RNA complexes. The nucleoid of this virion has been isolated and shown to have a density of 1.23 g/ml; it also contains a 60-70S nucleic acid species.
Further Changes in Differentiation State Accompanying the Conversion of Chinese Hamster Cells to Fibroblastic Form by Dibutyryl Adenosine Cyclic 3′:5′-Monophosphate and Hormones
Authors: Hsie Abraham W. , Jones Carol , Puck Theodore T.
Published: May 2006

The morphological conversion
in vitro
of Chinese hamster ovary cells to a fibroblast form by a relatively large amount of dibutyryl adenosine cyclic 3′:5′-monophosphate, or by a combination of small amounts of this compound and testosterone, is attended by appearance of the following additional properties: acquisition of strict contact inhibition of growth; reorientation of the random growth pattern into one in which cells grow parallel to their long dimension; disappearance of the randomly distributed, knob-like, pseudopodal structures around the cell periphery; induction of collagen synthesis; and decrease in the ability to be agglutinated and rounded up by plant agglutinins and specific cell antibodies. The changes in these characteristics are consistent with the conversion from a malignant to a normal fibroblastic state. This conversion is under genetic control, as demonstrated by the production of specific mutants with altered characteristics. The response to testosterone is specific since steroids like estradiol and hydrocortisone are inactive, and others have limited activity. Some prostaglandins are equal in activity to testosterone and 5α-dihydrotestosterone. This system appears useful in study of the regulation of phenotypic expression in mammalian cells.
The Dynamics of Life, V. Applying the Steady-State Theory of Mutations to Human Cancer
Authors: Erying Henry , Stover Betsy J. , Brown Russell A.
Published: May 2006

In papers I, II, and III of this series the steady-state theory of mutations was developed and applied to the extensive data on the effect of radiation on beagles acquired here during the past twenty years. In this paper the theory is used to interpret H. B. Dorn's data on the incidence of 21 kinds of cancer in both male and female Americans. The theory shows the nature of the heterogeneity in the population of various disorders. The agreement found confirms the steady-state theory of mutations in an interesting way.
The Spectrum of Seminormal Operators
Authors: Pincus Joel D.
Published: May 2006

With every pair of bounded self-adjoint operators {
U,V
} on Hilbert space such that
VU - UV
= (1/π
i
)
C
, where
C
is trace class, there is associated a certain function of two complex variables called the determining function of the pair. It was previously shown how the determining function can be obtained as the solution of a certain Riemann-Hilbert problem canonically associated with the pair, and how the complete spectral multiplicity theory for both
U
and
V
can be obtained from the determining function. We now show, under the condition that
C
is semidefinite, that the determining function method leads to a simple characterization of the spectrum of the seminormal operator
T
=
U
+
iV
.
Isolation and Properties of RNA Replicases Induced by SP and FI Phages
Authors: Haruna I. , Itoh Y. H. , Yamane K. , Miyake T. , Shiba T. , Watanabe I.
Published: May 2006

New RNA replicases were isolated and purified from
Escherichia coli
Q13 infected with SP or FI phages showing different serological properties. These replicases showed a template specificity different from that of Qβ replicase.
The Gramicidin A Transmembrane Channel: Characteristics of Head-to-Head Dimerized π
(L,D)
Helices
Authors: Urry D. W. , Goodall M. C. , Glickson J. D. , Mayers D. F.
Published: May 2006

A series of helical structures for gramicidin A, with alternating L and D residues, are characterized as to number of residues per turn, atoms in hydrogenbonded rings, and dihedral angles. Because of alternating peptide C-O directions, these helices are capable of forming head-to-head hydrogen-bonded dimers with the capacity of functioning as transmembrane channels. The dimers are characterized as to channel length, pore size, and expected ion selectivity.

In a test of the proposed head-to-head association for channel formation, the malonyl dimer [
N
,
N
′-(dideformyl gramicidin A)-malonamide] was synthesized. The chemical and conformational integrity of the product was verified by nuclear magnetic resonance; in lipid bilayer studies, the dimer was found to be a potent mediator of ion conductance with the predicted concentration dependence.

Thus, the results on malonyl gramicidin A prove head-to-head association in formation of the transmembrane channel, and the results are consistent with the specific geometrical configuration involved in head-to-head dimerization of π
(L,D)
helices. At this stage, the action of gramicidin A on membranes with lipid-layer thicknesses of 30 Å or less can best be understood in terms of the π
(L,D)
helix with 6.3 residues per turn.
New Integral Representations for Solutions of Cauchy's Problem for Abstract Parabolic Equations
Authors: Donaldson J. A.
Published: May 2006

A study has been made of Cauchy's problem for a class of abstract parabolic differential equations. Our study is based upon a transformation that maps solutions of second-order abstract Cauchy problems into solutions of first-order. This is a preliminary report on some of the results obtained. These results include (
1
) new representations for solutions of abstract parabolic equations, (
2
) applications to the heat equation, (
3
) a discussion of solution representations for second-order abstract Cauchy problems, and (
4
) applications to nonwell posed (in the sense of Hadamard) Cauchy problems.
Hibernation: Alteration of Mitochondrial Membranes as a Requisite for Metabolism at Low Temperature
Authors: Raison John K. , Lyons James M.
Published: May 2006

Lipids of mitochondrial membranes from hepatic cells of active ground squirrels apparently go through a phase change induced at approximately 23°C similar to the phase change in mitochondria of homeotherms. This change was indicated by the activity of succinate oxidase from the isolated mitochondria exhibiting a nonintersecting discontinuous Arrhenius plot. This discontinuity in the Arrhenius plot is not evident with mitochondria from the livers of hibernating squirrels, which indicates that the temperature-induced phase change in the mitochondrial membranes has been eliminated. These findings suggest that physical properties of the mitochondrial membrane change in relation to the process of hibernation.
The Spiral Wave of Our Galaxy Near Inner Lindblad Resonance
Authors: Mark James W-K.
Published: May 2006

The dispersion relationship for short-wavelength spiral density waves in our Galaxy has been refined to remove the divergences that occurred in wave number and in amplitude as inner Lindblad resonance is approached. The wave is found to be evanescent in an annular region near 4 kpc. By 3 kpc, the inward propagating trailing wave is completely absorbed. The outgoing leading wave is suppressed compared to the trailing one because it begins in the evanescent state. Throughout this region of inner Lindblad resonance, a smooth wave amplitude has been obtained, and it has a sharp peak correlating well with the observed density of ionized hydrogen.
Fluctuations in Nonequilibrium Systems
Authors: Nicolis G. , Prigogine I.
Published: May 2006

The theory of fluctuations is extended to nonlinear systems far from equilibrium. Systems whose evolution involves two separate time scales, e.g., chemically reacting mixtures near a local equilibrium regime, are studied in detail. It is shown that the usual stochastic description of chemical kinetics based on a “birth and death” model is inadequate and has to be replaced by a more detailed phase-space description. This enables one to develop for such systems a plausible mechanism for the emergence of instabilities, in which the departure from the steady state is governed by large fluctuations of macroscopic size, while small thermal fluctuations are still described by a generalization of Einstein's equilibrium theory. On the other hand, far from a local equilibrium regime, infinitesimal fluctuations may increase and attain macroscopic values. In this case the system evolves to a state of “generalized turbulence”, in which the distinction between macroscopic averages and fluctuations becomes meaningless.
Requirement for GTP in the Initiation Process on Reticulocyte Ribosomes and Ribosomal Subunits
Authors: Shafritz D. A. , Laycock D. G. , Crystal R. G. , Anderson W. F.
Published: May 2006

The requirement for GTP in the initiation process on reticulocyte ribosomes and ribosomal subunits has been examined by studying Met-tRNA
F
binding, ribosome-dependent [γ-
32
P]GTP hydrolysis, and peptide-bond formation with puromycin. Met-tRNA
F
binding can be obtained with the methylene analogue, 5′-guanylylmethylene diphosphonate, as well as GTP, and it is not inhibited by fusidic acid or several other inhibitors of protein synthesis. This reaction can be performed with the 40S subunit and has the same requirements as the Met-tRNA
F
-binding reaction with washed ribosomes. Ribosome-dependent [γ-
32
P]GTP hydrolysis can be obtained with the initiation factor M
2A
using either washed ribosomes or the 40S subunit. This reaction is also not significantly inhibited by fusidic acid. Peptide-bond formation between puromycin and Met-tRNA
F
, however, is inhibited by fusidic acid, and does not occur if the methylene analogue of GTP is substituted for GTP. These data suggest that the binding of the initiator tRNA to the 40S subunit does not require the hydrolysis of GTP, but that at least one GTP hydrolysis event must occur after Met-tRNA
F
binding in order for the first peptide bond to be formed.
Harmonic Analysis and H
2
-Functions on Siegel Domains of Type II
Authors: Ogden R. D. , Vági S.
Published: May 2006

It is known that the distinguished boundary of a Siegel domain of type II can be identified with a simply connected nilpotent Lie group of step two. The Plancherel formula for this group and the irreducible unitary representations which enter into that formula are determined. The H
2
-space of the domain and its Szegö kernel are characterized in terms of the harmonic analysis of the above group, in particular, the integral representations for H
2
-functions due to Gindikin and Korányi-Stein are shown to be instances of the Fourier inversion formula.
An Activity from Mammalian Cells That Untwists Superhelical DNA—A Possible Swivel For DNA Replication
Authors: Champoux James J. , Dulbecco Renato
Published: May 2006

Nuclei from secondary mouse-embryo cells contain an activity capable of untwisting closed-circular DNAs containing either negative or positive superhelical turns. The activity has no apparent effect on a closed-circular DNA containing no superhelical turns, and is not due to the combined action of an endonuclease and polynucleotide ligase. The enzyme apparently acts by introducing a single-strand nick into the DNA, forming a DNA-enzyme complex that allows the strands to rotate relative to the helix axis before reversing the reaction and sealing the break. The enzyme might possibly serve as a swivel during DNA replication.
Some Structural and Antigenic Properties of Intracisternal A Particles Occurring in Mouse Tumors
Authors: Kuff Edward L. , Lueders Kira K. , Ozer Harvey L. , Wivel Nelson A.
Published: May 2006

Intracisternal A-particles were isolated from three different myeloma lines in BALB/c mice and from cultured neuroblastoma cells of A/J origin. All preparations contained a major structural protein with an apparent molecular weight near 70,000 as estimated by electrophoretic mobility in sodium dodecyl sulfate-containing polyacrylamide gels. Solubilization of this component by sodium dodecyl sulfate was dependent on prior or concomitant treatment with sulfhydryl compounds. The size distribution of A-particle proteins was markedly different from that observed for extracellular murine leukemia and mammary tumor viruses. Rabbit antiserum was developed that reacted with the major A-particle protein in both complement fixation and immunodiffusion assays. The antigen was detected in isolated neuroblastoma A-particles, in cytoplasmic membrane fractions prepared from various mouse tumors known to contain intracisternal particles, but not in preparations from normal mouse cells, in samples of leukemia and mammary tumor virus, or in JLS-V9 cells infected with Rauscher leukemia virus. Conversely, isolated A-particles did not react in complement fixation or immunodiffusion assays with antisera against leukemia virus antigens.
Replication of ϕX174 DNA by
Escherichia coli polA
-
In Vitro
Authors: Olivera Baldomero M. , Bonhoeffer Friedrich
Published: May 2006

Lysates of an
Escherichia coli polA
-
strain convert single-stranded DNA from ϕX174 virus to the double-stranded replicative form with high efficiency on cellophane discs. The initiation of synthesis of the complementary strand appears to be rate limiting; once initiation occurs, the chain is propagated rapidly. Under these conditions, the unsealed replicative form accumulates and is slowly converted to the sealed form; this conversion requires the activity of the DPN-dependent DNA ligase.
Nonrandom X-Chromosome Inactivation—an Artifact of Cell Selection
Authors: Mukherjee Barid B. , Milet Rene G.
Published: May 2006

The present study shows that a high degree of variability in the distribution of XX and XY cells exists among various tissues of artificially assembled or spontaneously occurring mouse chimeras. This variation from the expected equal distribution in various tissues of an animal may have resulted from random distribution, unequal segregation, or selective differences of such cells during development. This variation may also explain the observed intertissue and interanimal variations in the distribution of inactive paternal and maternal X-chromosomes in some mammalian females.
Genetic Modification of Electric Properties in an Excitable Membrane
Authors: Kung Ching , Eckert Roger
Published: May 2006

A behavioral deficiency produced by a single gene mutation in
Paramecium aurelia
was traced to impaired electric excitability of the cell membrane. Evidence is presented that the mutant membrane does not exhibit the normal depolarization-activated increase in calcium conductance responsible for regenerative depolarization in the wild type. Other electric properties characteristic of the wild-type membrane remain normal in the mutant.
3-Hydroxypropionate: Significance of β-Oxidation of Propionate in Patients with Propionic Acidemia and Methylmalonic Acidemia
Authors: Ando Toshiyuki , Rasmussen Karsten , Nyhan William L. , Hull David
Published: May 2006

[l-
14
C]Propionate administered intravenously was metabolized to methylmalonate, to 3-hydroxypropionate, and to methylcitrate in the urine of a patient with methylmalonic acidemia. L-[
U
-
14
C]Isoleucine and L-[
U
-
14
C]valine were also converted to urinary methylmalonate and to 3-hydroxypropionate in the patient. Two patients with propionic acidemia due to a defect in propionyl-CoA carboxylase metabolized [
l
-
14
C]propionate to uninary methylcitrate and 3-hydroxypropionate. The appearance of radioactive 3-hydroxypropionate in the urine after the administration of these compounds indicates that β-oxidation of propionyl-CoA through acryloyl-CoA was functioning in these patients. The conversion of valine to 3-hydroxypropionate suggests that valine is oxidized by way of propionate and propionyl-CoA in man.
Persistence of Thymidine Kinase Activity in Mitochondria of a Thymidine Kinase-Deficient Derivative of Mouse L Cells
Authors: Attardi Barbara , Attardi Giuseppe
Published: May 2006

The cell line LM(TK
-
) Cl 1D, a derivative of mouse L fibroblasts deficient in thymidine kinase (EC 2.7.1.21) that shows very little thymidine kinase activity in extracts of whole cells as compared to the parental line, and that does not incorporate thymidine or 5-bromodeoxyuridine into nuclear DNA, has maintained the capacity to incorporate these precursors into mitochondrial DNA at a substantial rate. The amount of [
methyl
-
3
H]thymidine incorporated into mitochondrial DNA of LM(TK
-
) Cl 1D cells after long-term labeling has been conservatively estimated in different experiments to be between 30 and 60% of that incorporated into mitochondrial DNA or nuclear DNA of strain A9, an L-cell derivative without any thymidine-kinase dificiency; by contrast, the incorporation of thymidine into nuclear DNA of Cl 1D cells is less than 1% of that in A9 cells. These results strongly suggest that the loss of thymidine kinase activity in the extramitochondrial compartment of LM(TK
-
) Cl 1D cells has not been accompanied by the loss of the mitochondria-associated enzyme activity, pointing to a different genetic or epigenetic control of the extramitochondrial and mitochondrial enzymes.
Biochemically Differentiated Neoplastic Clone of Schwann Cells
Authors: Pfeiffer S. E. , Wechsler W.
Published: May 2006

Four clonal lines have been established in tissue culture from a transplantable tumor of cervical nerve-root induced transplacentally with ethylnitrosourea in an inbred BD-IX rat strain. One clone (RN-2) has several biochemical properties of the nervous system that led to its classification as a Schwann cell line, namely (
a
) the synthesis of the nervous system specific protein S-100, (
b
) a high specific activity of 2′,3′-cyclic nucleotide-3′-phosphohydrolase, an enzyme present in high specific activity only in glial cells, and (
c
) the presence of a basic protein related by immunological crossreaction, molecular size, and amino-acid composition to the encephalitogenic protein from beef brain myelin. Clone RN-2 has a high plating efficiency, a doubling time of about 20 hr, and a mean of 43 chromosomes of normal morphology. Clone RN-2 has also been inoculated subcutaneously into syngeneic rats and grown as a clonal tumor with good growth properties.
Fusion of Mammalian Somatic Cells by Microsurgery
Authors: Diacumakos Elaine G. , Tatum Edward L.
Published: May 2006

Mammalian somatic-cell hybrids can be formed in a direct and precise manner by microsurgery. Fusion of cells brought about in this way permits selection of specific, identifiable cells of the same or different types or species and their fusion at telophase.
Purification and Properties of Bacteriophage T4-Induced RNA Ligase
Authors: Silber Robert , Malathi V. G. , Hurwitz Jerard
Published: May 2006

An enzyme, purified 300-fold from
Escherichia coli
infected with bacteriophage T4, catalyzes the conversion of 5′-termini of polyribonucleotides to internal phosphodiester bonds. The reaction requires ATP and Mg
++
. For every 5′-
32
P terminus rendered resistant to alkaline phosphatase, an equal amount of AMP and PPi are formed. Various polyribonucleotides are substrates in the reaction; to date, the best substrate is [5′-
32
P]polyriboadenylate. With the latter substrate, no evidence of intermolecular reaction was obtained. However, the 5′-
32
P termini of poly(A) rendered resistant to alkaline phosphatase are also resistant to attack by RNase II, polynucleotide phosphorylase, and low concentrations of venom phosphodiesterase. Since the product formed with poly(A) lacks 3′-hydroxyl ends, as measured with these exonucleases, the enzyme appears to convert linear molecules of polyriboadenylate to a circular form by the intramolecular covalent linkage of the 5′-phosphate end to the 3′-hydroxyl terminus.
Bidirectional Transcription and the Regulation of Phage λ Repressor Synthesis
Authors: Spiegelman Willard G. , Reichardt Louis F. , Yaniv Moshe , Heinemann Stephen F. , Kaiser A. D. , Eisen Harvey
Published: May 2006

There are two promoters for transcription of gene
cI
in phage λ, the gene that codes for phage repressor. The promoters, called
pre
and
prm
, are located on the distal (
pre
) and proximal (
prm
) sides of gene
cro
, which itself is adjacent to
cI
. Since
cI
and
cro
are transcribed in opposite directions,
cI
transcription initiating at
pre
gives rise to an antisense transcript of
cro
, while
cI
transcription initiating at
prm
does not.
Pre
, active after infection of a sensitive cell, is stimulated by products of phage genes
cII
and
cIII
, and may be located at the site defined by the mutant
cY
.
Prm
is active in an established lysogen. These conclusions are based on measurements of the rates of synthesis of antisense
cro
RNA,
cI
RNA, and repressor protein in infected and lysogenic cells. To measure antisense RNA, an assay based on the formation of nuclease-resistant, double-stranded RNA, specific to the
cro
region, was developed. These results raise the possibility that bidirectional transcription of
cro
has a regulatory function in phage λ.