bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification and Immunological Characterization of the Major Internal Protein of the RD-114 Virus
Authors: Oroszlan S. , Bova D. , White M. H. Martin , Toni R. , Foreman C. , Gilden R. V.
Published: May 2006

The major internal protein of the RD-114 virus that appeared in a human tumor cell line, RD, after passage through fetal cats was purified by isoelectric focusing and used to prepare antibody in guinea pigs. The protein has a molecular weight of 33,500 in sodium dodecyl sulfate-polyacrylamide gels, and an isoelectric point of 9.1. This contrasts with a molecular weight of 25,000 and an isoelectric point of 8.3 obtained previously for the major protein of cat C-type viruses. The RD-114 protein carries determinants common to all mammalian C-type viruses but not species-specific determinants of cat, mouse, rat, hamster, chicken, and Russell's viper C-type viruses. In addition, two other proteins found in cat virus preparations were not detected in the RD-114 virus. Antiserum to the RD-114 viral protein proved highly specific by complement fixation and gel diffusion assays, and, in addition to the above mentioned mammalian viruses, the antiserum did not react with concentrates of the Woolly monkey or Gibbon ape C-type viruses. These data support the conclusion that the RD-114 virus is a human virus activated by passage through fetal cats. Until additional isolates are made from human cells, the identity of the RD-114 virus as a human C-type tumor virus cannot be fully established; however, this would be highly probable if the species-specific group-specific antigen of RD-114 could be demonstrated in human tumor and/or embryonic tissues.
Effect of Dibutyryladenosine 3′:5′-Cylic Monophosphate on Growth and Differentiation in
Caulobacter crescentus
Authors: Shapiro Lucille , Agabian-Keshishian Nina , Hirsch Allen , Rosen Ora M.
Published: May 2006

Caulobacter crescentus
goes through a series of morphological changes during its life cycle, including the coincident expression of synthesis of flagella, pili, and receptor sites for DNA bacteriophage. Upon transfer of a mixed population of cells to medium containing lactose as the sole carbon source, these changes were blocked for about 20 hr until β-galactosidase activity became apparent. The addition of dibutyryl cyclic AMP to the blocked cultures brought about the resumption of cell differentiation, growth, and the appearance of β-galactosidase activity within 1 hr. Unlike
Escherichia coli
, the intracellular and extracellular concentrations of cyclic AMP in
C. crescentus
did not vary under several growth conditions, including catabolite repression. It would appear, therefore, that although there is an effect of cyclic AMP on the induction of β-galactosidase and differentiation in
C. crescentus
, regulation of these processes occurs without consistent changes in the cellular level of this nucleotide.
Re-Evaluation of the Arizona Cloud-Seeding Experiment
Authors: Neyman Jerzy , Osborn Herbert B. , Scott Elizabeth L. , Wells Marcella A.
Published: May 2006

The apparent effect of cloud seeding on the average 24-hr precipitation in the Santa Catalina Mountains during the two programs of the 7-year-long Arizona experiment was found to be a 30% loss of rain (
P
= 0.06). Considering rainy days only, the apparent effect is a 34% loss of rain (
P
= 0.03). On South-East days the apparent loss was 40% (
P
= 0.03). The analysis of the diurnal variation in the amounts of hourly precipitation brought out two suggestions: (
i
) more active silver iodide enters the clouds through seeding at their bases than at the -6°C level; (
ii
) the population of experimental days includes two categories with opposite responses to seeding: augmentations of rain in one case and losses in the other. These suggestions require independent confirmation.
A New Characterization of Quasi-Analytic Classes of C
∞
-Functions
Authors: Darst R. B.
Published: May 2006

It is shown that a basic class
C
{

M
n

} of C
∞
-functions contains only quasi-analytic functions if, and only if, every function in
C
{

M
n

} maps Borel sets onto Borel sets.
Membrane Transport Against the External Driving Force Due to Mass Transfer-Reaction Coupling
Authors: Bailey James E. , Luss Dan
Published: May 2006

Coupling between chemical reactions and transport phenomena can cause the substrate concentration at the surface of a membrane to be lower on the substrate-rich side than the substrate-lean side. Thus, the diffusing flux inside the membrane may be counter to the overall external concentration driving force. Graphical solutions of various steady states of such membranes are presented.
Preferential Inhibition by Proflavine of the Hormonal Induction of Glutamine Synthetase in Embryonic Neural Retina
Authors: Wiens A. W. , Moscona A. A.
Published: May 2006

The hormonal induction of glutamine synthetase (EC 6.3.1.2) in embryonic neural retina tissue
in vitro
is blocked preferentially and reversibly by proflavine (3,6-diaminoacridine) in the absence of cell or DNA replication; cell viability is not affected, and the synthesis of total cellular proteins and RNA is only slightly reduced. In the induction of this enzyme, there is a rapid increase in the synthesis and accumulation of the enzyme selectively elicited by the steroid inducer; for this effect, transcription is essential. Radioimmunochemical measurements have shown that proflavine inhibits induction by prevention of
de novo
synthesis of catalytically active and immunologically reactive glutamine synthetase protein. It does not measurably affect the uptake of the steroid inducer by the retina cells. Since the translation of this enzyme by preformed RNA templates is not stopped by proflavine, the inhibitory effect of proflavine on induction is apparently due to interference with transcriptional or pretranslational processes required for the provision of active transcripts for enzyme synthesis. The finding that proflavine inhibits preferentially a tissue-specific, inducible differentiation in postmitotic embryonic neural cells offers new approaches to the study of regulation of gene expression in eukaryotes.
Specific Fractionation of Immune Cell Populations
Authors: Rutishauser U. , Millette C. F. , Edelman G. M.
Published: May 2006

Antigen-binding cells from spleens of immune and nonimmune mice were isolated by the method of fiber fractionation. Binding of the lymphoid cells to derivatives of nylon fibers made with various antigens was prevented by the presence of the respective free antigen, as well as by antibodies to mouse immunoglobulins. Antigen-binding cells specific for dinitrophenyl groups were separated from direct and indirect plaque-forming cells of the same specificity. Spleen cells from immune and nonimmune animals were fractionated according to their relative affinities for antigen, and the percentage of antigen-binding cells in the spleens of nonimmune animals was estimated. A comparison of the numbers and relative affinities of immunoglobulin receptors of immune and nonimmune populations indicated that after immunization only those antigen-binding cells of higher affinities were increased in number. This finding suggests that the specificity of clonal selection depends not only upon the binding of antigen to a lymphoid cell but also upon the capacity of that cell to be triggered to mature and replicate.
Characterization and Partial Purification of the Acetylcholine Receptor from
Torpedo
Electroplax
Authors: Eldefrawi Mohyee E. , Eldefrawi Amira Toppozada
Published: May 2006

Binding of acetylcholine in the concentration range 1 nM-1 μM was measured by equilibrium dialysis to a particulate preparation of
Torpedo
electroplax, without or with prior treatment of the tissue with one of three chemical modifying reagents. Significant reduction in binding of acetylcholine resulted after treatment with 1,4-dithiothreitol,
p
-chloromercuribenzoate, or
p
-(trimethylammonium)-benzenediazonium fluoroborate. Partial reversal of the reduction in binding occurred when dialysis was performed in the presence of 5,5′-dithiobis-(2-nitrobenzoic acid) or potassium ferricyanide (in the case of treatment with dithiothreitol), and 2-mercaptoethanol (in the case of treatment with
p
-chloromercuribenzoate). It is concluded that the functional acetylcholine-receptor macromolecule of
Torpedo
electroplax has disulfide bond(s), sulfhydryl group(s), and one or more of the amino acids vulnerable to diazotization by
p
-(trimethylammonium)-benzenediazonium fluoroborate. This, plus the effect of phospholipase C (EC 3.1.4.3) in elimination of detectable binding of acetylcholine after electrofocusing, is additional evidence that the functional acetylcholine receptor is a phospholipoprotein or a phospholipid-protein complex, which has a low isoelectric point of 4.5 ± 0.2, yet is denatured by exposure to low pH for 24 hr. Due to this adverse effect, recovery of binding of acetylcholine after electrofocusing, as detected by equilibrium dialysis or ultrafiltration, is only 23% and, so far, only 6.3-fold purification of functional acetylcholine receptors by this technique is possible.

Three or two forms of acetylcholinesterase (EC 3.1.1.7), whose peaks have isoelectric points ranging from 4.3 to 7.2, appear after electrofocusing of
Torpedo
extracted with 1% Triton X-100 or Lubrol, respectively. The major peak in either preparation has an isoelectric point of 5. Although the peaks of the functional acetylcholine receptors and of acetylcholinesterase of
Torpedo
electroplax are separable by electrofocusing, it has not been possible to isolate fractions that contain functional receptors but that are free of acetylcholinesterase. The opposite is possible.
In Vitro Synthesis of Enzymes of the Tryptophan Operon of Escherichia coli
Authors: Pouwels P. H. , Rotterdam J. Van
Published: May 2006

Two active enzymes of the tryptophan operon of
E. coli
, anthranilate synthetase (product of
trp E
and
trp D
) and tryptophan synthetase (EC 4.2.1.20) (product of
trp B
and
trp A
), have been synthesized in a DNA-dependent preparation for protein synthesis. Anthranilate synthetase and the two components of tryptophan synthetase (tryptophan synthetase A and B) are made
in vitro
in equimolar amounts, suggesting that regulation of the translation is similar
in vivo
and
in vitro
. Kinetics of the synthesis of the two enzymes suggest that transcription and translation proceed
in vitro
in a correct temporal sequence.
Heart Attacks: Possible Risk Factor
Authors: Page Irvine H.
Published: May 2006

Evidence is assembled from the literature to support the argument that myocardial infarction and death results from narrowing of coronary arteries—a process that may result from various causes, as discussed in this paper. Angiotensin and hypertension are suggested as among the chief components of such processes.
Patterns of Genetic Differentiation in the Slender Wild Oat Species
Avena barbata
Authors: Clegg M. T. , Allard R. W.
Published: May 2006

Allozyme frequencies at five enzyme loci were determined for 14 California populations of
Avena barbata
, a species introduced to California from the Mediterranean Basin during the colonization of North America. Allelic frequencies at these loci were also determined in Mediterranean collections of this species. The pattern of divergence of the California populations from the ancestral gene pool was not random and was strongly correlated with environment; thus, the pattern is not in accord with the hypothesis that most electrophoretically detectable variants are adaptively neutral. Rates of gene substitution in California were also not in accord with the neutrality hypothesis. The observations are, however, compatible with predictions of Neo-Darwinian evolutionary theory. We interpret these observations to indicate that natural selection plays a major role in determining the unique patterns of distribution of genetic variability in the slender wild oat in California.
Deletion Mutants of Bacteriophage ϕX174
Authors: Zuccarelli Anthony J. , Benbow Robert M. , Sinsheimer Robert L.
Published: May 2006

Mutants of bacteriophage ϕX174 have been isolated that are less dense than wild-type ϕX particles in CsCl. When mutant viral (+) strand DNA and wild-type complementary (-) strand DNA are hybridized, the resulting duplex molecules have single-stranded loops characteristic of wild-type-deletion heteroduplexes. The mutant bacteriophages fail to complement ϕX amber mutants in cistron
E
. We conclude that the mutant viruses have deleted approximately 7% of the ϕX genome in the region of cistron
E
.
Detection of RNA-Instructed DNA Polymerase and High Molecular Weight RNA in Malignant Tissue
Authors: Gulati S. C. , Axel R. , Spiegelman S.
Published: May 2006

An experimental procedure is detailed that permits the detection of 70S RNA-directed DNA synthesis in mouse mammary carcinomas. The DNA synthesized is complementary to the RNA of the mouse mammary tumor virus by molecular hybridization, thus, completing the proof that an RNA-instructed DNA polymerase has been identified. Further, RNA-instructed DNA polymerase and its 70S RNA template are physically associated in a particle that has a density characteristic of oncornaviruses. These experiments now provide the technology required to perform similar examinations of human neoplasias.
Induction of Malate Dehydrogenase Isoenzymes in Livers of Young and Old Rats
Authors: Kanungo M. S. , Gandhi Behrose S.
Published: May 2006

The activity of cytoplasmic malate dehydrogenase (EC 1.1.1.27) of livers of young (9-10 weeks) and old (60-70 weeks) rats decreases after adrenalectomy and increases after administration of cortisone to adrenalectomized rats. These changes are significantly lower in old rats. The induction by cortisone is inhibited by actinomycin D. Adrenalectomy decreases and cortisone increases the activity of mitochondrial malate dehydrogenase of young rats, but not of old rats. Cortisone, however, induces both mitochondrial and cytoplasmic malate dehydrogenase of the regenerating liver at both the ages. Thus, impairment of the inducibility of mitochondrial malate dehydrogenase that occurs in old age is repaired in dividing cells. Immunological studies on purified malate dehydrogenase from young and old rats show that the molecular species of the enzyme is apparently the same at both ages. The changes in activities of the enzymes seen in old age may be due to changes in template activity of the corresponding genes, which apparently do not change with age.
Mass Production of
Coelomomyces
, a Fungus That Kills Mosquitoes
Authors: Couch J. N.
Published: May 2006

In work on the control of mosquitoes by the fungus
Coelomomyces
, the main problem is a source of inoculum since the fungus has not been cultured artificially with production of sporangia. We reared the larvae of
Anopheles quadrimaculatus
in algal water instead of in water with soil. By addition of inoculum once or twice in small amounts, the larvae become infected, and many grow to large fourth instars whose bodies are filled with sporangia. Such larvae are perfect for inoculum. If inoculum is added in much larger amounts and so timed that sporangia will be discharging spores during the first, second, and third ecdyses up to 100%, infection occurs, most of the larvae dying as late second or early third instars. This type of infection is good for extermination of mosquitoes but not for production of inoculum. Crude field tests have averaged 60% infection.
The C-Group Pachytene Bivalent with a Locus Characteristic for Parachromosomally Situated Particulate Bodies (Parameres): A Provisional Map in Human Males
Authors: Hungerford David A. , Ashton Francis T. , Balaban Gloria B. , LaBadie Gundula U. , Messatzzia Linda R. , Haller Gail , Miller Alice E.
Published: May 2006

During prophase stages of the first meiotic division in human males, an autosomal divalent in the C group (autosomes 6-12) characteristically has associated with it, at a specific locus, small, DNA-containing bodies (parameres). A pachytene chromomere map is presented, as is evidence suggesting that the parameres are disposed in two lateral loops, each of which is coaxial with one of the homologs. Stereophotographs of stacks of plates from electron micrographs of serial ultrathin sections show the parameres in their
in situ
configuration to be composed of tightly compacted fibrils, 85-90 Å in diameter.
Expression of Aryl Hydrocarbon Hydroxylase Induction and Suppression of Tyrosine Aminotransferase Induction in Somatic-Cell Hybrids
Authors: Benedict W. F. , Nebert D. W. , Thompson E. B.
Published: May 2006

Aryl hydrocarbon hydroxylase activity is inducible in mouse 3T3 fibroblasts by benz[α]anthracene, whereas no detectable basal or inducible levels of this enzyme occur in rat-hepatoma tissue culture cells. Conversely, tyrosine aminotransferase activity is inducible in hepatoma cells by dexamethasone, whereas only low noninducible levels of this enzyme exist in 3T3 cells. In hybrids formed by fusion of these two parent lines, levels of inducible hydroxylase activity range from the same as, to more than 20-fold greater than, that in the 3T3 parent; aminotransferase levels remain very low and noninducible in all of these same hybrids. A majority of the 1S-chromosomal complement from each parent is retained in most of these hybrids. The kinetics of hydroxylase induction and degradation, responses of hydroxylase induction to actinomycin D and cycloheximide, and the relative thermolability of the control and induced activities are similar in the 3T3 parent and in the hybrids. Failure to inactivate any of the aminotransferase activity in the hybrids with antibody specific for the rat enzyme indicates that all of the basal noninducible aminotransferase activity is derived from the mouse 3T3 parent.
In Vitro
Synthesis of a Regulator of Mammalian Gene Expression
Authors: Colten Harvey R.
Published: May 2006

Peritoneal cells isolated from guinea pigs homozygous for a deficiency of the fourth component of complement (C4), produce
in vitro
a factor that induces the synthesis and secretion of functionally active human C4 by a human cell. This factor appeared to switch on production of C4 in the responsive cell without affecting total protein synthesis. The regulator factor is not species specific, inasmuch as
guinea pig
regulator affected a corresponding
human
gene function. Both synthesis of the factor and the response to it were inhibited by actinomycin D. The amount of regulator recovered from genetically deficient cells was about 5-10 times that recovered from normal guinea pig cells.
Isolation and Characterization of a Protein That Stimulates DNA Synthesis from Avian Myeloblastosis Virus
Authors: Leis Jonathan P. , Hurwitz Jerard
Published: May 2006

A protein has been isolated from avian myeloblastosis virus that stimulates the rate and yield of DNA synthesis primed by viral RNA with purified viral polymerase. It specifically affects the viral polymerase and does not stimulate other DNA polymerases under the conditions tested. The viral polymerase, in conjunction with this protein, transcribes extended single-stranded regions of DNA, and permits the enzyme to initiate synthesis from single-strand breaks in DNA.
Biological Activity of Human Chorionic Gonadotropin Released from Testis Binding-Sites
Authors: Dufau M. L. , Catt K. J. , Tsuruhara T.
Published: May 2006

The effect of testicular binding of human chorionic gonadotropin upon the biological activities of the hormone was examined by comparison of the binding and activation properties of
125
I-labeled gonadotropin before and after binding to rat testis
in vitro
. Biologically active
125
I-gonadotropin taken up by rat testis was dissocated from testis binding-sites at low pH and evaluated for its ability to bind again to testis, adenylate cyclase activation, and stimulation of steroidogenesis during subsequent incubation with fresh testis. Binding to tissue receptor-sites for 4 hr did not impair the biological properties of gonadotropin, though hormone remaining in the incubation medium had reduced affinity for tissue binding-sites during subsequent incubation with rat testes. In comparison to the original preparation,
125
I-labeled gonadotropin previously eluted from specific binding-sites of rat testis showed significantly increased binding activity and stimulation of cyclic AMP and testosterone release during further incubation with rat testes
in vitro
. The enhancement of biological activity of the eluted hormone is attributable to affinity purification of the original hormone preparation by selective uptake at receptorsites. These results demonstrate that gonadotropin is not inactivated or degraded during combination with gonadotropin receptors of rat testis.
Stationary Spherical Vortices in a Perfect Fluid
Authors: Pekeris C. L.
Published: May 2006

Necessary conditions are derived for a spherical vortex in a perfect fluid to be stationary in the case when the velocities depend on a single surface harmonic. The motion is indeterminate unless an additional condition is imposed. In the case when this condition is incompressibility, the equations are solved, yielding a class of stationary spherical vortices.
Tautomerism of Uracil and Thymine in Aqueous Solution: Spectroscopic Evidence
Authors: Daniels Malcolm
Published: May 2006

Excitation spectra for triplet state formation and fluorescence emission from uracil and thymine in neutral aqueous solution at room temperature are anomalous when compared to the absorption spectra of uracil and thymine.

The experimental data are critically examined with respect to three molecular models;
Model 1
, which is characterized by increased intersystem crossing from higher vibrational levels of S
1
;
Model 2
, in which fluorescence is attributed to a (π,π
*
) state, whereas intersystem crossing occurs from an (
n
π
*
) state; and
Model 3
, in which fluorescence is attributed to a tautomer I, while triplet yields originate from tautomer II. Reasons are presented for discarding
Models 1
and
2
, and it is demonstrated that the observed excitation spectra complement each other with respect to the absorption spectrum, such that the quantum yields of triplet formation and fluorescence emission become independent of exciting wavelength. It is suggested that the fluorescing tautomer I has the N
3
-C
4
enol structure, while the triplet-forming tautomer II is most likely the predominant diketo form.
Prokaryotic Algae Associated with Australian Proterozoic Stromatolites
Authors: Licari G. R. , Cloud Preston
Published: May 2006

Five instances of association between distinctive stromatolites and blue-green algal nannofossils are recorded from a 100-m sequence of carbonate rocks about 1.6 × 10
9
years old, along the south side of Paradise Creek, northwestern Queensland, Australia. No eukaryotes were identified in any of these systematically limited assemblages, although they are known from rocks as old as 1.3 × 10
9
years in eastern California. Thus, eukaryotes
may
not have appeared until after 1.6 × 10
9
years ago (but before 1.3 × 10
9
years ago). The associations observed would also be consistent with (but do not prove) a biotic influence on stromatolite morphology. As is usual among prePaleozoic forms described, the morphology of the nannofossils is very similar to living forms, displaying marked evolutionary conservatism. Primary orientation of stromatolitic laminae and columns is not invariably convex upward, as conventionally believed, but convex away from and parallel to the initial point or surface of attachment, which may be horizontal or even downward beneath overhangs.
Self Purification of Two Serine Endopeptidases
Authors: Awad W. M. , Ochoa Maria S. , Toomey T. P.
Published: May 2006

We have reported that a serine protease from Pronase, homologous with bovine chymotrypsin, is both active and stable in 6 M guanidinium chloride. The present investigation examined the possibility that this unique property might be used to permit the enzyme to engage in its own purification by cleaving companion proteins to low-molecular-weight products. Analysis with model substrates of the several specific activities that were originally present revealed that only the activity against
N
α-acetyl-L-tyrosine ethyl ester was demonstrable after incubation for 100 hr in the denaturant. After a moderate loss within the first 24 hr, the remaining activity against this ester was conserved for many days thereafter. Pronase was routinely incubated for 1 week at 22° in 6 M guanidinium chloride at pH 8.0 where the esterases showed maximal activity. Analysis of the products of incubation revealed unexpectedly the presence of two serine proteases that were easily separated. After purification to homogeneity these components proved themselves to be the previously demonstrated subtilisin-like and stable chymotrypsin-like enzymes. The only amino-terminal residue of the chymotrypsin-like enzyme is isoleucine, as it is in the earlier, conventionally purified product. The migration of the single band of this enzyme during acrylamide gel electrophoresis was the same whether purified by the past or present technique. No free amino-terminal group was demonstrable in the subtilisin-like enzyme. This study presents a unique and rapid technique for isolation of these proteases, with the first reported purification to homogeneity of the subtilisin-like component. These enzymes may be useful as probes for local relaxations of conformation in substrate proteins. Furthermore, they may contribute to the preparation of enzyme-free non-protein macromolecules.
Distribution of Pyrimidine Oligonucleotides in Strands L and H of
Bacillus subtilis
DNA
Authors: Rudner Rivka , Ledoux Mary , Mazelis Anne
Published: May 2006

The distribution of pyrimidine oligodeoxynucleotide clusters in L and H strands of
Bacillus subtilis
DNA separated by methylated albumin-Kieselguhr has been determined. Preparations of native and single-stranded DNA were degraded with diphenylamine in formic acid, and the released isostichs with the general formula of Py

n

P

n
+1

were separated on DEAE-cellulose by chain length. Eleven isostichs were obtained for strands L and H in unequal proportions. Each isostich fraction was subfractionated by base composition on DEAE-cellulose at pH 3.0. 61 Pyrimidine oligonucleotide clusters were separated from the H strand and only 46 from the L strand. The findings show a higher degree of asymmetry between the strands in the distribution of cytosine-rich clusters as compared with thymine-rich clusters. The longest cytosine oligodeoxynucleotide present in both strands is of chain length 5. There is an unusually high distribution of thymine oligodeoxynucleotides of length 5-11. Up to chain length 6, the distribution of thymine oligodeoxynucleotides between the strands is about equal; from chain length 7 to 11 they occur predominantly in the H strand.
Photophosphorylation by Monomolecular Films at an Air-Water Interface
Authors: McPhee J. , Brody S. S.
Published: May 2006

An acetone extract of chloroplast particles, when layered on an aqueous surface, exhibited light-dependent phosphorylation. Studies with the firefly-tail enzyme assay, as well as with
32
P-labeled inorganic phosphate, show an initial release of adenosine triphosphate (a step that is apparently only light-triggered), followed by a light-dependent uptake of the labeled inorganic phosphate into adenosine diphosphate and adenosine triphosphate.
Direct Evidence for Messenger Activity of Influenza Virion RNA
Authors: Siegert W. , Bauer G. , Hofschneider P. H.
Published: May 2006

In a cell-free system of
Escherichia coli
, RNA from influenza virus particles is translated into a polypeptide antigenically identical with the ribonucleoprotein and several more proteins, some of which correspond in size to viral structural components.
In Vivo
Splicing of Protein: One Continuous Polypeptide from Two Independently Functioning Operons
Authors: Apte B. N. , Zipser David
Published: May 2006

Active-β-galactosidase (EC 3.2.1.23) is often formed in
rec
-
merozygotes containing a pair of mutations in the
z
gene of the
lac
operon. Contrary to expectation, with certain pairs of mutants this enzyme, upon dissociation, does not yield two independent polypeptides but only a single continuous protomer. Both genetic recombination and suppression have been ruled out as the source of this phenomenon. Therefore we believe we are observing the synthesis of one protein from two independently functioning genes.
Cell-Surface Interactions: Differential Inhibition by Proflavine of Embryonic Cell Aggregation and Production of Specific Cell-Aggregating Factor
Authors: Hausman R. E. , Moscona A. A.
Published: May 2006

Cell recognition and morphogenetic aggregation of embryonic cells into tissues are mediated by specific macromolecules in the cell surface (cell-aggregating factors). A factor specific for embryonic neural retina cells was demonstrated; its synthesis is required for histotypic reaggregation of retina cell suspensions. We show that proflavine (3,6-diaminoacridine) preferentially and reversibly suppresses production of the cell-aggregating factor and thereby inhibits normal cell reaggregation. If such proflavine-treated retina cells are exogenously supplied with the retina-specific factor, they reaggregate. The selectivity of these effects supports the postulated significance of specific cell-surface components in cell association into tissues; the results indicate that proflavine may be a useful molecular probe for studying formation of specific cell-surface components and their role in various cell interactions.
ε-Adenylylated Glutamine Synthetase: An Internal Fluorescence Probe for Enzyme Conformation
Authors: Chock P. B. , Huang C. Y. , Timmons R. B. , Stadtman E. R.
Published: May 2006

A fluorescent derivative of ATP, ε-ATP, was used to adenylylate glutamine synthetase (EC 6.3.1.2) from
Escherichia coli
enzymatically. The ε-adenylylated enzyme exhibits similar catalytic properties and inhibitor susceptibility to those of the naturally adenylylated enzyme. The fluorescence properties of the ε-adenosine and of tryptophan residues of the enzyme were used to study ligand-induced conformational changes involving alterations of the tryptophan regions and the adenylylation site of the protein. Binding of Mn
2+
to the ε-adenylylated enzyme is accompanied by a decrease of ε-adenosine fluorescence as compared to the effect observed for the Mg
2+
binding. An ADP binding study shows that at low ADP concentration, ADP causes enhancement of the tryptophan fluorescence only, reflecting the binding to unadenylylated subunits; and at high ADP concentration, ADP causes not only enhancement of the fluorescence, but also a quenching of the fluorescence of enzyme-bound ε-AMP, reflecting binding to the adenylylated subunits. Dissociation constants calculated from these fluorescence changes agree well with those determined from binding studies of ADP to adenylylated and unadenylylated enzymes. Binding of the feedback inhibitor, alanine, to Mn
2+
-dependent glutamine synthetase causes enhancement of the ε-AMP fluorescence, from which a dissociation constant of 1.5 mM was calculated for the inhibitor. The fluorescence changes observed due to ligands binding suggest that Mg
2+
and Mn
2+
stabilize different conformational states of the enzyme.
Resistance to Colicins E3 and K Induced by Infection with Bacteriophage f1
Authors: Zinder Norton D.
Published: May 2006

When infected with the filamentous phage f1,
Escherichia coli
K-12 strains are 20- to 40-times more resistant to colicins K and E3 than are uninfected cells. The colicins are adsorbed normally and are blocked in their action at some subsequent stage of their action. Productive infection of virions is not necessary for induction of resistance. The evidence presented implicates the product of gene III of the phage, a minor protein in the virion, as being responsible for this resistance. The simplest interpretation of the results is that this gene product blocks the penetration of colicins which is necessary for their action.
Pressure Effect on the Membrane Action of a Nerve-Blocking Spin Label
Authors: Hsia J. C. , Boggs J. M.
Published: May 2006

A reversible nerve-blocking spin label, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was used to study the nature of anesthetic-binding sites in nerve membranes as a function of pressure. The nerve-blocking effect of TEMPO is enhanced under pressure. At atmospheric pressure, TEMPO blocks nerve conduction by solubilizing in the apolar region of the nerve membrane. However, the nerve-conduction-block by TEMPO at 150 atm of helium was related to the binding of TEMPO to a pressure-induced high-affinity polar site in the nerve membrane. The new TEMPO-binding site could not be detected in lipid model membranes and, thus, the involvement of membrane protein in the new site was inferred. Pressure may induce a nerve membrane conformation change in the presence of TEMPO.

The observation that under different pressure, a single anesthetic, i.e., TEMPO, was capable of blocking nerve conduction by binding to two different sites within the nerve membrane, supports the view that there are multiple anesthetic receptor sites, which differ in chemical composition and location within the nerve membrane. These sites, when occupied by different classes of anesthetics, produce the general phenomenon of nerve-conduction block. The enhancement of nerve-conduction block by pressure may be due to the increased concentration of TEMPO in the new site in the nerve membrane under pressure.
Formation of Lipid-Bound Oligosaccharides Containing Mannose. Their Role in Glycoprotein Synthesis
Authors: Behrens Nicolas H. , Carminatti Hector , Staneloni Roberto J. , Leloir Luis F. , Cantarella Ana I.
Published: May 2006

Incubation of GDP-[
14
C]mannose with liver microsomes and magnesium ions led to the formation of dolichol monophosphate mannose and of other acidlabile compounds that contain oligosaccharides. Formation of these compounds was enhanced by addition of an acceptor lipid in the same fractions of DEAE-cellulose chromatography where bound dolichol is found. Alkaline treatment of the oligosaccharides, obtained by acid methanolysis, followed by paper electrophoresis, gave rise to the formation of two positively charged substances believed to be formed by deacetylation of hexosamine residues. Incubation of the oligosaccharide-containing compounds with liver microsomes and manganese ions resulted in a transfer to endogenous protein. The role of dolichol derivatives in glycoprotein synthesis is discussed.
Can a non-Mendelian Mutation Affect Both Chloroplast and Mitochondrial Ribosomes?
Authors: Boynton John E. , Burton William G. , Gillham Nicholas W. , Harris Elizabeth H.
Published: May 2006

Chloroplast ribosomes isolated from a spectinomycin-resistant mutant (
spr-1-27-3
) of
Chlamydomonas reinhardtii
that displays non-Mendelian inheritance fail to bind labeled antibiotic, in contrast to ribosomes from wild-type cells.
In vitro
resistance of this mutant appears to result from the absence of a specific protein in the small subunit of the chloroplast ribosome. However, chloroplast protein synthesis in the mutant and wild type shows identical sensitivity to spectinomycin in short-term
in vivo
experiments where ribulosediphosphate carboxylase serves as the marker. Long-term experiments demonstrate that the mutant can grow in the presence of spectinomycin only when acetate is supplied as a carbon source. Mitochondrial structure and function of the mutant are not affected by the antibiotic, whereas chloroplast structure and function are. Apparently, the mitochondrion, rather than the chloroplast, of this mutant is resistant to spectinomycin
in vivo
. We hypothesize that the gene product of the
spr
locus is a protein common to both chloroplast and mitochondrial ribosomes. The mutant gene product,
in vivo
, confers resistance on mitochondrial, but not chloroplast, ribosomes. We suppose that the mutant
spr
protein loosely attaches to chloroplast ribosomes
in vivo
so that the antibiotic is bound and blocks protein synthesis, but it dissociates during isolation, resulting in loss of the binding site.
Spectral Properties of an Oxygenated Luciferase—Flavin Intermediate Isolated by Low-Temperature Chromatography
Authors: Hastings J. W. , Balny Claude , Peuch Christian Le , Douzou Pierre
Published: May 2006

Bacterial luciferase catalyzes the oxidation of reduced flavin mononucleotide by molecular oxygen; long-chain aldehyde is required for light emission. At 20° the bioluminescence has a lifetime of tens of seconds, while excess reduced flavin is removed by way of nonenzymatic autoxidation in less than a second. This observation indicates the existence of a long-lived enzyme intermediate, which has been postulated to be a peroxide of the enzyme-bound reduced flavin. This intermediate was isolated and studied at low temperature (-20°), where it has a lifetime measured in days. It has an absorption with a single band peaking at 372 nm, and fluorescence emission centered at about 485 nm, which might be expected for the postulated flavin peroxide. Upon conversion to product, flavin mononucleotide-like absorption and fluorescence appear, supporting the postulate that flavin turns over in the reaction. Upon injection into buffer at 20° with added aldehyde, bioluminescence occurs. Based on a stoichiometry of one flavin per luciferase molecule, the specific activity of the intermediate is equal to that of pure luciferase.
Hybridization of Leucyl-Transfer Ribonucleic Acid Isoacceptors from Green Leaves with Nuclear and Chloroplast Deoxyribonucleic Acid
Authors: Williams Gene R. , Williams Alice S. , George S. A.
Published: May 2006

Chromatographically distinct isoacceptors of leucyl-tRNA from mature bean leaves were all observed to hybridize with bean chloroplast and nuclear DNA in a ratio similar to that exhibited by the unfractionated leucyl-tRNA. Under the same hybridization conditions, maize tRNA failed to form a stable hybrid with bean DNA, and levels of hybridization between bean-leaf leucyl-tRNA and nuclear or chloroplast DNAs from tobacco and maize were relatively small.
Isolation and Partial Characterization of α- and β-Tubulin from Outer Doublets of Sea-Urchin Sperm and Microtubules of Chick-Embryo Brain
Authors: Luduena Richard F. , Woodward Dowo O.
Published: May 2006

Two kinds of tubulin (α and β) have been described in microtubules from many different systems. In this study a discontinuous acrylamide-gel system containing sodium dodecyl sulfate was used to separate milligram quantities of α- and β-tubulin from microtubules of chick-embryo brain and from outer doublets of sea-urchin sperm. The isolated tubulins were characterized by peptide mapping and automated sequencing of the first 25 NH
2
-terminal amino acids. Our results show that α- and β-tubulin are related but distinctly different proteins and that each one has been highly conserved in the course of evolution.
A Mutant of
Escherichia coli
with a New, Highly Efficient Promoter for the Lactose Operon
Authors: Bruenn Jeremy , Hollingsworth Helen
Published: May 2006

We have isolated a mutant of
E. coli
whose maximal rate of synthesis of
lac
mRNA is 25-fold greater than that of its parental wild-type strain. The mutant also shows alterations in the kinetics of β-galactosidase synthesis, the functional half-life of β-galactosidase mRNA, and the properties of
lac
repressor.
3-Bromo-2-Butanone 1,4-Bisphosphate as an Affinity Label for Ribulosebisphosphate Carboxylase
Authors: Hartman Fred C. , Welch Mary H. , Norton I. Lucile
Published: May 2006

3-Bromo-2-butanone 1,4-bisphosphate has been synthesized in an attempt to find a reactive analog of ribulose 1,5-bisphosphate for labeling the active site of ribulosebisphosphate carboxylase (EC 4.1.1.39). The reagent irreversibly inactivates the carboxylase from spinach, and several observations suggest that the inactivation results from modification of an active-site residue: (
1
) Ribulose 1,5-bisphosphate protects against inactivation. (
2
) The extent of reagent incorporation shows that modification of one residue per catalytic site can account for the inactivation. (
3
) Comparisons of autoradiograms of peptide maps prepared from carboxylase treated with the
32
P-labeled reagent in the absence and presence of substrate indicate that inactivation results from a fairly selective modification. (
4
) Although the reagent's greatest inherent reactivity is toward sulfhydryl groups, inactivation of the enzyme is due to alteration of an amino-acid residue other than cysteine.
A Magnetic Suspension Osmometer
Authors: Beams J. W. , Hodgins M. G. , Kupke D. W.
Published: May 2006

The magnetic suspension balance is used for the measurement of very small osmotic pressures. The apparatus is essentially the same as that previously used for the measurement of the density and viscosity of protein solutions except that the magnetically suspended buoy is modified to make it pressure sensitive. The method is especially useful for the measurement of osmotic pressure in small samples of dilute solutions (about 10
-6
M) or of substances with molecular weights greater than 10
5
. A height-sensing device has been developed which is not dependent upon the visual precision of the operator.
Statistical Mechanics Applied to Cooperative Ligand Binding to Proteins
Authors: Chay Teresa Ree , Ho Chien
Published: May 2006

By using the lattice statistical argument, we have shown that for a protein whose subunits have the same number of neighbors, the three parameters (

K
AB
, K
BB

, and

K
S
K
t

) in the sequential theory formulated by Koshland, Nemethy, and Filmer [
Biochemistry
(1966) 5, 365] can be reduced to two parameters. One of the parameters,
Z
, measures the strength of the subunit interactions and is related to the apparent free energy of interaction (Δ
F
°
I
) by
Z
= exp (-Δ
F
°
I
/2
mkT
), where
m
is the number of neighbors in a subunit and
kT
has the usual meaning. In addition, we relate Wyman's allosteric binding potential [
Advan. Protein Chem
. (1964) 19, 223] to the canonical partition function of the McMillan-Mayer theory [
J. Chem. Phys
. (1945) 13, 276]. An explicit form relating the apparent free energy of interaction and the Hill coefficient is given for an allosteric protein that has nonequivalent and independent ligand-binding sites. The present formulation can be used to account for a number of recent experimental results on hemoglobins.
Downwind and Upwind Effects in the Arizona Cloud-Seeding Experiment
Authors: Neyman Jerzy , Scott Elizabeth L. , Wells Marcella A.
Published: May 2006

The principal subject of this report is a comparison of precipitation on days with seeding with that without seeding, averaged over those rain gauges that on each particular day were “downwind,” “upwind,” or to the sides. Two estimates of relevant wind directions are used, based on successive radiosondes at Tucson that bracketed the scheduled time of seeding. By use of these radiosondes, the apparent effects of seeding on rain in downwind localities 90-180 miles (145-290 km) away from target were found to be an apparent 45% loss of rain (
P
= 0.002) and an apparent 34% loss of rain (
P
= 0.028), respectively. Other results indicate considerable geographic heterogeneity.
Chromosomal Control of Mating Activity in
Drosophila pseudoobscura
Authors: Sherwin Richard N. , Spiess Eliot B.
Published: May 2006

Lines containing two third-chromosome inversions (Arrowhead and Pikes Peak) of
Drosophila pseudoobscura
selected for fast and slow mating speed were crossed to a multichromosomal, dominant marker inversion stock, and strains with various combinations of chromosomal derivation were tested for their mating activity. When lines were selected isodirectionally with the known third-chromosome control, the third chromosome was found to possess major epistatic control over mating speed, followed by the fourth, with no appreciable effect from the first and second. However, polygenic modification mating activity was found throughout the genome when selection was applied opposite to the original third-chromosome control. The work reported here strengthens the evidence that the adaptive role of chromosomal polymorphism has a behavioral basis in mating activity.
Primary Structure of Somatostatin, A Hypothalamic Peptide That Inhibits the Secretion of Pituitary Growth Hormone
Authors: Burgus Roger , Ling Nicholas , Butcher Madalyn , Guillemin Roger
Published: May 2006

Somatostatin, a peptide isolated from ovine hypothalamic tissue that inhibits the release of radioimmunoassayable growth hormone
in vitro
from rat or human pituitary cells or
in vivo
in rats, has the primary structure [Formula: see text]. The structure was established by submitting the carboxymethylated peptide, the carboxymethylated tryptic digest, and the chymotryptic digest of the peptide to Edman degradation. Degradation products were analyzed by amino-acid analysis, as well as in some cases by determination of N-termini by dansylation or by determination of phenylthiohydantoins by mass spectrometry.
Synthesis of Stable RNA in Stringent
Escherichia coli
Cells in the Absence of Charged Transfer RNA
Authors: Kaplan Samuel , Atherly Alan G. , Barrett Anna
Published: May 2006

It has been possible to demonstrate the complete absence of either charged tRNA
Glu
or charged tRNA
Val
at 42° by the use of two stringent strains of
E. coli
, one temperature-sensitive for glutamyl-tRNA synthetase and the other temperature-sensitive for valyl-tRNA synthetase. In both strains, stable RNA synthesis ceases, and guanosine tetraphosphate accumulates upon incubation at the nonpermissive temperature. Unique among a series of antibiotics tested, only tetracycline was able to stimulate stable RNA synthesis and to cause disappearance of the guanosine nucleotide. In this regard tetracycline and the “relaxed” gene product appear to be analogous.
The “Trophic” Value of Foods
Authors: Williams Roger J. , Heffley James D. , Yew Man-Li , Bode Charles W.
Published: May 2006

Foods must furnish (
i
) calories, which can readily be measured, and (
ii
) raw materials necessary for the building and maintenance of metabolic machinery which makes possible fuel utilization. We have called this “beyond-calorie” quality of food its “trophic” value.

This concept has more unity than appears on the surface, and is capable of approximate measurement by biological testing as our experiments show.

The trophic value of a food cannot be ascertained from food composition tables because only a smattering of the necessary information is commonly furnished. A food cannot support life if it is missing, or deficient with respect to, any one of the necessary nutrients. A tabulation which includes only a few nutrients—e.g., calcium, thiamin, riboflavin, niacin, phosphorus, and iron—can be woefully misleading, especially if these individual nutrients have been added by way of fortification.

The measurement we have applied to a number of foods is potentially valuable for comparing similar food products: two grains, two breads, two milk products, or for comparison of the same food grown, processed, or preserved in different ways. By using essentially this method we have found that barnyard eggs are somewhat superior to battery eggs, but that whether they are fertile or infertile makes no difference.

We are of the opinion that extensive biological testing of many commercial food products is highly desirable to help promote human health and better internal environments for our cells and tissues.
The Nature of the Colicin K of
Escherichia coli
K235
Authors: Goebel Walther F.
Published: May 2006

When
E. coli
K235 is grown in the presence of mitomycin C it elaborates part of its colicin as a protein, which has been purified by gel filtration and electrofocusing to yield a product that is serologically homogeneous. The colicin K of
E. coli
K235 is chemically and serologically identical with that of
Proteus mirabilis
. Like the colicin of the latter, the
E. coli
bacteriocin occurs in multiple forms that exhibit slight differences in mobility upon electrophoresis in a polyacrylamide gel.