bluuebunny/crossref_metadata_2025 huggingface dataset:
Dopamine-β-Hydroxylase Activity in Mouse Neuroblastoma Tumors and in Cell Cultures
Authors: Anagnoste Berta , Freedman Lewis S. , Goldstein Menek , Broome John , Fuxe Kjell
Published: May 2006

Dopamine-β-hydroxylase activity is present in mouse neuroblastoma C-1300 tumors. The activity is proportional to the weight of the tumor. Serum activity is markedly increased in mice that bear the tumors. Treatment of mice with 5-bromodeoxyuridine causes marked inhibition of tumor growth and decrease of dopamine-β-hydroxylase activity in the serum. The histochemical studies reveal that 1-5% of the cells in mouse C-1300 neuroblastoma tumors contain catecholamines and that catecholamine-containing processes terminate mainly around blood vessels of the tumor. Dopamine-β-hydroxylase is present in clonal neuroblastoma cell lines. The cell line with the greater tendency to form axon-like processes has a higher activity of this enzyme.
Observation of Cooperative Ionizations in Hemoglobin
Authors: Huestis Wray H. , Raftery Michael A.
Published: May 2006

19
F-Nuclear magnetic resonance studies of specifically fluorinated hemoglobin derivatives have been used to determine the apparent pK
a
of the histidine β146 imidazole in deoxyhemoglobin. The titration of this residue was found to be abnormally sharp, particularly in the presence of diphosphoglyceric acid. The explanation advanced for this unusual titration curve may have implications for the mechanism of cooperative ligand binding. The possible role of such ionizations is discussed in light of some chemical evidence that the cooperative binding process is governed to a greater extent by internal nonpolar forces than by electrostatic interactions of exposed groups.
Loss of Simian Virus 40 DNA-RNA Hybrids from Nitrocellulose Membranes; Implications for the Study of Virus-Host DNA Interactions
Authors: Haas Martin , Vogt Marguerite , Dulbecco Renato
Published: May 2006

Complete hybrids of simian virus 40 (SV40)DNA and its complementary RNA (cRNA) are not retained on nitrocellulose membranes. At saturating cRNA concentrations, retention of the hybrids indicates incomplete homology between DNA and RNA, probably due to incorporation of host DNA in the viral DNA; this effect is most pronounced when DNA is produced in cells infected at high multiplicity. Hybrids between DNA of Chinese hamster cells transformed by SV40 and cRNA are retained if the DNA fragments are long, but they are lost if the DNA is sheared to less than the length of an SV40 DNA molecule. Hence, in cells examined with about six SV40 genomes per cell, each genome is individually integrated. The results may explain previous discrepancies in the estimation of the number of viral genomes in transformed cells.
Location of Promoter and Operator Sites in the Biotin Gene Cluster of
Escherichia coli
Authors: Cleary Paul P. , Campbell Allan , Chang Robin
Published: May 2006

Biotin independence in
E. coli
requires five closely linked genes,
bioA, bioB, bioF, bioC
, and
bioD
. The residual gene activity of deletion mutants has been studied by complementation and enzyme assays. Deletion of the left end of the
bioA
gene does not impair expression of the remaining genes, but deletions from the left extending into
bioB
abolish all gene expression. Nonsense mutations in
bioB
reduce expression of
bioC, bioF
, and
bioD
. Therefore, the four genes,
bioB, bioF, bioC
, and
bioD
, are transcribed as a unit from left to right, from a promotor located between
bioA
and
bioB
.

Expression of the
bio
genes is repressible by added biotin. Deletions removing the left end of
bioA
do not affect repressibility of
bioD
. Therefore the operator, as well as the promoter, lie to the right of
bioA
. One deletion that removes
bioA, bioB
, and
bioF
renders the
bioD
gene constitutive, presumably by fusion to an unknown operon. Therefore, the operator lies to the left of
bioC
.
Creatine and the Control of Myosin Synthesis in Differentiating Skeletal Muscle
Authors: Ingwall Joanne S. , Morales Manuel F. , Stockdale Frank E.
Published: May 2006

These experiments provide evidence that creatine, an end product of contraction unique to muscle, is involved in the control of muscle-protein synthesis. Skeletal muscle cells formed both
in vitro
and
in vivo
synthesize myosin heavy chain faster when supplied creatine
in vitro
. The response is apparent within four hours after addition of creatine to the culture medium, and is dependent on concentration over a range of 10-100 μM creatine. The effect seems to be selective for cell-specific proteins(s), since the rate of total protein synthesis is unaffected.
Transamidase Reactions Involved in the Enzymic Coagulation of Semen: Isolation of γ-Glutamyl-ε-Lysine Dipeptide from Clotted Secretion Protein of Guinea Pig Seminal Vesicle
Authors: Williams-Ashman H. G. , Notides A. C. , Pabalan S. S. , Lorand L.
Published: May 2006

New supportive evidence is advanced in favor of the hypothesis that the enzymic coagulation of guinea pig semen involves transamidase reactions that result in the formation of γ-glutamyl-ε-lysine intermolecular cross linkages between molecules of a basic protein in seminal vesicle secretion. The dipeptide γ-glutamyl-ε-lysine was isolated in large quantities from proteolytic digests of the coagulated basic vesicular secretion protein that comprises the seminal clot.
Unification Theorem for the Two Basic Dualities of Homothetic Demand Theory
Authors: Samuelson Paul A.
Published: May 2006

When income elasticities of demand are all unity, every dollar being spent in the same proportions at all levels of income, a homogeneous-first-degree, concave utility function exists to serve as an unequivocal measure of real output. Dual to it, and with identical concavity and homogeneity properties, is the minimized-cost-per-unit-of-output, a function of prices. Distinct from this production dual is the indirect-utility dual, representing, except for algebraic sign, the maximized level of utility attainable as a function of prices relative to income. These basic alternative dualities are shown to be related by a unifying theorem: The logarithm of either of the pair of production-dual functions has for its indirect-utility dual the logarithm of the other function. What is shown to be the same thing, the indirect-utility dual of the output function is, except for sign, the reciprocal of the output's production-dual.
Ultraviolet-Stimulated DNA Synthesis in Toluenized
Escherichia coli
Deficient in DNA Polymerase I
Authors: Masker Warren E. , Hanawalt Philip C.
Published: May 2006

Ultraviolet (UV)-stimulated nonconservative DNA synthesis has been observed in
E. coli
rendered permeable to nucleoside triphosphates by exposure to toluene. This synthesis is detected in toluenized cells in which the background of UV-independent DNA synthesis is reduced by use of
dnaB
mutants temperature-sensitive for DNA replication and additionally deficient in DNA polymerase I. UV-stimulated nonconservative synthesis is also seen in
polA dnaE
mutants that are deficient in two of the three known DNA polymerases. The observed UV-stimulated repair-like synthesis requires the presence of the four deoxyribonucleoside triphosphates and ATP. This mode of synthesis appears to differ from the ATP-independent nonconservative DNA synthesis previously reported to occur in toluenized bacteria.
Malignant Lymphomas of African Children
Authors: Stewart Alice , Davies J. N. P. , Dalldorf Gilbert , Barnhart Frances E.
Published: May 2006

Clinical, pathologic, and epidemiologic observations of malignant tumors of children in sub-Sahara Africa suggest alternative theories of causation, and give insight into environmental influences that may play a large role in the etiology and form of malignant lymphatic tumors and cerebral neoplasms of infants.
Requirement of Proteins S5 and S9 from 30S Subunits for the Ribosome-Dependent GTPase Activity of Elongation Factor G
Authors: Marsh Robert C. , Parmeggiani Andrea
Published: May 2006

During CsCl isopycnic centrifugation at 20 mM Mg
++
,
Escherichia coli
30S ribosomal subunits specifically lose proteins S1, S2, S3, S5, S9, S10, and S14. The resultant 30S core is unable to stimulate the GTPase activity of EF-G in the presence of 50S subunits. Activity could be restored to a small extent by adding back S2, S5, or S9. However, when S5 and S9 were added together, they cooperatively produced 30S particles 1.5 times more active than the original native 30S subunits. The small amount of activity restored by S2 was simply additive to that restored by S5 or S9. None of the other split proteins showed any restoring capability. Ability of the various protein-deficient 30S particles to couple with 50S subunits corresponded closely to their activity in the EF-G GTPase reaction. It is concluded that S5 and S9 together enable the 30S subunit to participate in the formation of a GTPase-active 30S-50S-EF-G complex.
Double-Stranded RNA as an Inhibitor of Protein Synthesis and as a Substrate for a Nuclease in Extracts of Krebs II Ascites Cells
Authors: Robertson Hugh D. , Mathews Michael B.
Published: May 2006

Concentrations of double-stranded RNA above about 0.1 μg/ml inhibit translation of encephalo-myocarditis viral RNA and mouse globin messenger RNA in extracts of Krebs II ascites cells. Protein synthesis initially proceeds at the control rate, then abruptly shuts off in a manner similar to that observed in reticulocyte lysates [Hunt, T. & Ehrenfeld, E. (1971)
Nature New Biol.
230, 91-94]. Substantially higher concentrations of double-stranded RNA are required to give this effect in ascites extracts.

Subcellular fractions of Krebs II ascites cells contain a nucleolytic activity capable of digesting several natural and synthetic double-stranded RNAs. This nuclease is most active under conditions of protein synthesis, and part of the activity remains associated with ribosomes upon sedimentation. It is probably because of digestion of double-stranded RNA by this nuclease that higher concentrations of double-stranded RNA are required for inhibition of protein synthesis in Krebs cell extracts than in reticulocyte lysates.
Squalene and Sterol Carrier Protein: Structural Properties, Lipid-Binding, and Function in Cholesterol Biosynthesis
Authors: Ritter Mary C. , Dempsey Mary E.
Published: May 2006

Squalene and sterol carrier protein of liver plays a general role as a vehicle for cholesterol and its water-insoluble precursors; the carrier protein is essential for enzymic cholesterol synthesis. Liver microsomal enzymes contain a small amount of endogenous carrier protein, which is readily removed by washing or purification of the enzyme. Enzymic conversion to products of a cholesterol precursor·carrier protein complex is markedly faster than that for initially unbound sterol. The protomer form of the carrier protein has a molecular weight of 16,000; during sodium dodecyl sulfate gel electrophoresis one band is observed. Phospholipid facilitates the aggregation of the protomer to the oligomer form (>150,000 daltons; purified 720-fold) accompanied by the binding of cholesterol precursors to the oligomer. The carrier protein binds fatty acids as well as cholesterol precursors, suggesting that it may more generally be a
lipid carrier protein
with “squalene and sterol carrier protein” describing the functional aspects of the lipid carrier in cholesterol biosynthesis. Studies with several steroids and related compounds revealed that the binding sites of lipid carrier protein must contain highly specific hydrophobic and polar regions.
RNA Related to That of a Murine Leukemia Virus in Burkitt's Tumors and Nasopharyngeal Carcinomas
Authors: Kufe D. , Hehlmann R. , Spiegelman S.
Published: May 2006

RNA homologous to that of the Rauscher leukemia virus has been detected in Burkitt's lymphomas and nasopharyngeal carcinomas. Earlier excellent experimental evidence has linked these two human tumors with the Epstein-Barr virus, a DNA-containing agent.
Production of Mucopolysaccharides by Normal and Transformed Cells
Authors: Satoh C. , Duff R. , Rapp F. , Davidson E. A.
Published: May 2006

The rate of hyaluronic acid and sulfated mucopolysaccharide production was measured for hamster embryo fibroblasts and for general oncogenic lines derived by virus transformation. A striking increase in both the rate of hyaluronic acid synthesis and the amount of cell-associated polymer was observed after transformation by herpes simplex type-2 or SV40 virus. Although no corresponding change was observed for the sulfated polysaccharides, the proportion of heparan sulfate increased significantly after transformation.
Specific Recognition of Plasma Membranes by Embryonic Cells
Authors: Merrell Ronald , Glaser Luis
Published: May 2006

Methods have been developed for preparation of plasma membrane fractions from embryonic neural retina and cerebellum. These membrane fractions are specifically bound by intact cells of the original tissue (homotypic binding) and not by cells from the other tissue (heterotypic binding). Aggregation of neural retina cells and cerebellar cells is prevented by addition of homotypic membranes but not by heterotypic membranes. We conclude that, under our assay conditions, these embryonic cells specifically recognize homotypic membranes, and that the specificity of recognition is the same as in the initial step in the process of cellular aggregation.
Absence of Detectable IgM in Enzymatically or Biosynthetically Labeled Thymus-Derived Lymphocytes
Authors: Lisowska-Bernstein B. , Rinuy A. , Vassalli P.
Published: May 2006

Surface proteins of mouse thymus and spleen cells were radioiodinated with lactoperoxidase. After solubilization, the labeled proteins were precipitated by antibodies directed against mouse immunoglobulin chains; the precipitates were analyzed by radioautography after Na dodecyl sulfate-gel electrophoresis. Radioactive μ and L chains were absent from thymocyte extracts and conspicuous in spleen-cell extracts. The following cells were biosynthetically labeled for 4 hr [
35
S]methionine or 24 hr with [
14
C]leucine: (
1
) Thymocytes, (
2
) cortisoneresistant thymocytes [both treated with rabbit antisera cytotoxic to bone marrow-derived (B) lymphocytes and IgM-containing plasma cells, to kill possible contaminating nonthymus-derived cells], (
3
) “activated thymocytes” (allogeneic cell cultures of cortisone-resistant thymocytes), (
4
) human Daudi cells (a B lymphoblastic cell line), and (
5
) purified mouse B spleen lymphocytes devoid of plasma cells. Again no μ and L chains could be detected in thymocyte or thymus-derived cell extracts by immune precipitation and gel electrophoresis, while these chains were conspicuous in B-cell extracts. “Educated thymocytes,” obtained from spleens of lethally irradiated mice injected with syngeneic thymocytes and antigen, synthesized μ and L chains under similar conditions; this synthesis resulted from contamination of these cells by IgM-containing plasma cells.
A Mutant of 3T3 Cells with Cyclic AMP Metabolism Sensitive to Temperature Change
Authors: Willingham Mark C. , Carchman Richard A. , Pastan Ira H.
Published: May 2006

A mutant line of 3T3 (mouse fibroblast) cells with temperature-sensitive cyclic AMP (cAMP) metabolism was isolated by selecting for low substratum adhesiveness after a change in temperature. Although the mutant is identical in behavior to the parent cell at constant temperature, a rise or fall in temperature causes a fall in intracellular cAMP levels within seconds, followed by loss of adherence to the culture dish and retraction of cell processes. The mechanism of this fall in cAMP level is at least in part excretion into the medium. The decrease in adhesiveness and retraction of processes can be blocked by analogues of cAMP or agents that elevate intracellular cAMP. The properties of this mutant imply that cAMP is a direct regulator of cell shape and adhesiveness.
Generalized Verhulst Laws for Population Growth
Authors: Zwanzig Robert
Published: May 2006

The growth or decay of population of a single species interacting with a large number of other species (or environment) according to the Volterra-Lotka model is investigated. When the environment is initially very close to its equilibrium level, the growth of a single species follows a generalized Verhulst law, containing hereditary effects. The derivation, modeled on statistical mechanical theories of Brownian motion, leads also to a “noise” source and to its relation to the heredity kernel. A special case, where the hereditary kernel is a damped exponential function of time, is solved numerically. When growth starts at a level much below equilibrium, the population first overshoots equilibrium and then approaches it. When decay starts at a level much higher than equilibrium, the population first decays precipitously to a very low level and then slowly grows toward equilibrium.
Biological and Biochemical Evidence for an Interaction Between Marek's Disease Herpesvirus and Avian Leukosis Virus
In Vivo
Authors: Peters W. P. , Kufe D. , Schlom J. , Frankel J. W. , Prickett C. O. , Groupé V. , Spiegelman S.
Published: May 2006

The DNA-containing Epstein-Barr herpesvirus has been implicated in the etiology of Burkitt's lymphoma, a malignant tumor of children in Africa. Recently, however, particles possessing four biochemical characteristics of RNA tumor viruses have also been identified in these tumors. The fact that both types of viruses are found suggests that an interaction between them may be playing a role in the etiology of Burkitt's lymphoma. To explore this possibility with a defined animal model, experiments were performed with the avian Marek's disease, a malignant lymphoproliferative disease associated with a herpesvirus. Controlled contact studies demonstrated that tumorigenesis in a line of isolator-derived, barrier-sustained, specific pathogen-free chickens requires exposure to both the Marek's disease herpesvirus and an avian leukosis virus, Rous-associated virus, type 2. Exposure to either agent alone did not result in tumors. Molecular hybridization experiments to cytoplasmic RNA from similarly contact-exposed conventional Cornell S-line chickens provided further evidence for the occurrence of an interaction between Marek's disease herpesvirus and the avian leukosis virus.
Dependence of the Proton Magnetic Resonance Spectra on the Oxidation State of Flavodoxin from
Clostridium MP
and from
Peptostreptococcus elsdenii
Authors: James Thomas L. , Ludwig Martha L. , Cohn Mildred
Published: May 2006

The broadening of protein nuclear magnetic resonances in the spectra of the semiquinone forms of flavodoxins derived from
Clostridium MP
and
Peptostreptococcus elsdenii
relative to the resonances in the oxidized and reduced forms is highly selective. Spectra from both species of flavodoxin indicate that conformational differences between the oxidized and fully reduced states are minor and, consequently, the broadening in the semiquinone form is ascribed to the paramagnetic effect of the flavin free radical. The chemical shifts of the paramagnetically broadened lines are used in conjunction with x-ray crystallographic models to assign peaks to amino-acid residues in the proximity of the flavin mononucleotide. Species-dependent differences in the spectra can generally be attributed to differences in amino-acid composition and sequence. The spectra from both species of flavodoxin indicate that there is slow exchange between oxidized and semiquinone forms or reduced and semiquinone forms of the flavodoxins with a limit of
k
ex
< 50 sec
-1
for the exchange rate.
Tissue-Specific Transcription of the Globin Gene in Isolated Chromatin
Authors: Gilmour R. S. , Paul J.
Published: May 2006

RNA was transcribed from chrmation from mouse fetal liver or brain, by use of DNA-dependent RNA polymerase of
Escherichia coli
. Globin messenger RNA sequences in the transcript were measured with complementary DNA copied from globin messenger RNA with RNA-dependent DNA polymerase. Globin messenger RNA sequences were found in RNA newly transcribed from chromatin from erythropoietic tissue but not in that transcribed from brain chromatin.
Lipid Bilayer Phase Transition: Density Measurements and Theory
Authors: Nagle J. F.
Published: May 2006

The overall change of density for dipalmitoyl lecithin bilayers agrees with a general order-disorder theory and yields about seven gauche rotations per molecule for the biologically relevant high-temperature phase. The shape of the curve of density against temperature is similar to the result of an exact calculation on a specific model, which gives a 3/2-order phase transition.
Assignment of the T-Antigen Gene of Simian Virus 40 to Human Chromosome C-7
Authors: Croce Carlo M. , Girardi Anthony J. , Koprowski Hilary
Published: May 2006

Hybrid cell clones between
mouse
cells deficient in thymidine kinase (EC 2.7.1.21) and two different
human
cell lines transformed by simian virus 40 (SV40) and deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) were examined for SV40 tumor (T) antigen(s). Concordant segregation of the gene(s) for SV40 T antigen and human chromosome C-7 was observed in these hybrids. The human chromosome C-7 which contains the gene(s) for SV40 T antigen is preferentially retained by the majority of the hybrid clones tested. When hybrid clones positive and negative for SV40 T antigen, derived from the fusion of SV40-transformed Lesch-Nyhan fibroblasts with mouse cells, were fused with CV-1 permissive cells, SV40-specific V antigen was observed only in the cultures derived from fusion of the hybrid clones positive for T antigen. This result indicates a linkage relationship between human chromosome C-7, SV40 T-antigen gene(s), and SV40 genome(s) integrated in the human transformed cells.
Temperature-Dependent Formation of Dimers and Oligomers of Mitochondrial DNA in Cells Transformed by a Thermosensitive Mutant of Rous Sarcoma Virus
Authors: Nass Margit M. K.
Published: May 2006

In chick-embryo fibroblasts infected by T5, a temperature-sensitive mutant of Schmidt-Ruppin Rous sarcoma virus, the level of catenated dimeric and oligomeric mitochondrial DNA is temperature-dependent and correlates with the phenotypic manifestation of transformation. At the permissive temperature (36°), where transformation is expressed, the 2- to 3-fold elevated level characteristic of cells transformed by the wild-type Rous sarcoma virus was observed, but at the nonpermissive temperature (41°), at which cells appear normal and behave normally, the oligomer level was characteristic of uninfected cells. Temperature shifts from 41 to 36° and vice versa resulted in phenotypic reversion and reversals of the respective levels of multiple-length DNA. Cellular growth rates were not altered. Treatment of control cells with cycloheximide resulted in a 5-fold increase of oligomeric DNA, whereas exposure to 9-β-D-arabinofuranosyladenine had little effect. With both inhibitors, nuclear but not mitochondrial DNA synthesis was inhibited. The possible relation of formation of oligomeric mitochondrial DNA to alterations in the mitochondrial membranes of transformed cells and to inhibition of protein synthesis in the cytoplasm is discussed.
Synthesis of [
3
H]DNA Complementary to Ovalbumin Messenger RNA: Evidence for Limited Copies of the Ovalbumin Gene in Chick Oviduct
Authors: Harris Stephen E. , Means Anthony R. , Mitchell William M. , O'Malley Bert W.
Published: May 2006

Accumulation of ovalbumin messenger RNA in chick oviduct is absolutely dependent upon estrogen. After estrogen treatment, ovalbumin comprises 60-65% of the total oviduct protein. We used maximally stimulated animals to extract and partially purify the ovalbumin messenger RNA. The final product was enriched about 100-fold in activity with respect to this specific messenger RNA. This ovalbumin messenger RNA fraction was used to direct the synthesis of a complementary [
3
H]DNA in the presence of RNA-dependent DNA polymerase isolated from avian myeloblastosis virus. The complementary [
3
H]DNA (specific radioactivity, 8 × 10
7
cpm/μg) was a faithful transcript since about 90% would hybridize back to the original messenger RNA template. Ovalbumin complementary [
3
H]DNA was reannealed with an excess of chick-oviduct total DNA. The kinetics of this reaction indicate that only one copy of the ovalbumin gene exists in each haploid genome. These data suggest that estrogen may affect the oviduct genome to stimulate production of large numbers of ovalbumin messenger RNA molecules from a single copy of the ovalbumin gene.
Unique Nuclear DNA Sequences in the Involved Tissues of Hodgkin's and Burkitt's Lymphomas
Authors: Kufe D. W. , Peters W. P. , Spiegelman S.
Published: May 2006

Previous studies have demonstrated that Hodgkin's, Burkitt's, and other human lymphomas contain particulate elements encapsulating 70S RNA and RNA-dependent DNA polymerase. [
3
H]DNA probes endogenously synthesized by these particles were used to demonstrate that the nuclear DNA of the lymphomas contain particle-related sequences that cannot be detected (less than 1/20th of a copy per genome) in the DNA of normal cells. This result agrees with our earlier findings in human leukemias. The data are inconsistent with any etiologic concept that invokes germ-line transmission of at least one complete copy of the particulate information associated with the malignancy. The unique sequences found in the nuclear DNA of Burkitt's and Hodgkin's tissues are related to each other but not to the DNA of the Epstein-Barr virus.
Fructose 1,6-Bisphosphatase: The Role of Lysosomal Enzymes in the Modification of Catalytic and Structural Properties
Authors: Pontremoli S. , Melloni E. , Balestrero F. , Franzi A. T. , De Flora A. , Horecker B. L.
Published: May 2006

Seasonal variations in the properties of rabbit-liver fructose 1,6-bisphosphatase have now been linked to corresponding changes in the levels of proteolytic activity in the liver extracts. Incubation of native fructose 1,6-bisphosphatase with purified liver lysosomes causes a 3-fold increase in catalytic activity at pH 9.2, with a smaller, and variable, decrease in activity tested at pH 7.5. These changes in catalytic properties are accompanied by the appearance of a smaller subunit, as was previously reported for the enzyme treated with subtilisin. AMP, a negative modulator of fructose bisphosphatase activity, protects against this action of lysosomes. This proteolytic modification of fructose bisphosphatase by lysosomal enzymes may play a role in the modulation of gluconeogenesis.
Induction of Immunoglobulin M Synthesis and Secretion in Bone-Marrow-Derived Lymphocytes by Locally Concentrated Concanavalin A
Authors: Andersson Jan , Melchers Fritz
Published: May 2006

Stimulation of bone-marrow-derived lymphocytes by locally concentrated concanavalin A involves first an increased intracellular synthesis of total protein and of immunoglobulin M at 10-14 hr, followed by the initiation of secretion of protein and of IgM at 24-30 hr after stimulation. Differentiation into immunoglobulin-producing and -secreting cells after stimulation is manifested by (
a
) a rate of IgM synthesis that increases continuously over total protein synthesis, and (
b
) an increased rate of IgM secretion with concomitant decrease of secretion of other proteins. Within stimulated bone-marrow-derived cells, IgM molecules were found mainly in their 7S form, together with some light-μ-heavy-chain precursors. Small amounts of polymerized 19S IgM are found associated with the cells. Only fully assembled 19S IgM was found secreted into the extracellular medium. Polymerization into the pentamer therefore takes place shortly before, or simultaneously with, secretion. Intracellular 7S IgM contains only glucosamine and mannose residues, with traces of fucose and galactose residues. Secreted 19S IgM has the full complement of carbohydrates with glucosamine, mannose, fucose, galactose, and
N
-glycolylneuraminic acid residues. During polymerization and secretion from the cells, IgM molecules therefore acquire all of the semiterminal and terminal residues of their carbohydrate groups.
A Native Ribonucleoprotein Complex from
Escherichia coli
Ribosomes
Authors: Crichton R. R. , Wittmann H. G.
Published: May 2006

An RNA-protein complex was isolated from the 50S subunit of
E. coli
ribosomes after trypsin digestion. The complex contains only one protein, L24. Treatment of the complex with pancreatic ribonuclease results in digestion of most of the RNA; however, an RNA fragment of about 100 nucleotides in length is stable to nuclease digestion and remains bound to the protein. It is also possible to reconstitute a complex from 23S RNA and isolated L24; nuclease digestion of this complex produces a resistant RNA fragment of the same size as the native complex. The protein can still bind to 23S RNA after
N
-methylation of about 20% of its lysine residues. Thus, by use of
N
-methylated L24 labeled with either
14
C or
3
H, the binding stoichiometry of the reconstituted complex was established; binding of L24 to RNA once again renders the protein trypsin-resistant. This would appear to be a good system for the study of RNA-protein interactions.
Congenital Neutropenia:
In Vitro
Growth of Colonies Mimicking the Disease
Authors: L'Esperance Pierre , Brunning Richard , Good Robert A.
Published: May 2006

Congenital neutropenia is a lethal disease characterized by recurrent infections beginning in the neonatal period, absence of neutrophils in the peripheral blood, eosinophilia, and monocytosis. The bone marrow shows an apparent “maturation arrest” of the neutrophil series at the promyelocyte stage. Granulocytic colonies grown
in vitro
in soft agar medium show normal development of eosinophilic colonies and monocyte-macrophage colonies, but defective neutrophil maturation. The abnormal colonies observed contained only myeloblasts and promyelocytes. Thus, it seems to have been possible to mimic
in vitro
the abnormal differentiation that is observed
in vivo
.
Structure of Sickled Erythrocytes and of Sickle-Cell Hemoglobin Fibers
Authors: Finch J. T. , Perutz M. F. , Bertles J. F. , Döbler Johanna
Published: May 2006

Deoxyhemoglobin from patients homozygous for sickle-cell anemia (deoxyhb S) aggregates into long straight fibers. These may extend through most of the length of the sickled cell, forming either square or hexagonally packed bundles with lattice constants of 170-180 Å. Each fiber is a tube made up of six thin filaments, which are wound around the tubular surface with a helical pitch of about 3000 Å. Each filament is a string of single hemoglobin molecules linked end to end at intervals of 62 Å in dry and 64 Å in wet fibers. Molecules in neighboring filaments are in longitudinal register so that they form flat hexagonal rings; these rings are stacked so that successive ones are rotated about the fiber axis by 7.3°. The whole structure repeats after about eight rings. In this structure each molecule makes contact with four neighbors. The likely orientation of the molecules and points of contact between them are discussed. Similar filaments are also observed in normal deoxygenated erythrocytes, but in much lower concentration and aggregated into fibers of irregular diameter. No filaments appear in oxygenated sickle, or normal, adult cells, nor in oxygenated or deoxygenated fetal cells.
Photoreversible Conductance Changes Induced by Phytochrome in Model Lipid Membranes
Authors: Roux Stanley J. , Yguerabide Juan
Published: May 2006

The plant protein phytochrome induces photoreversible conductance changes when added to a black lipid membrane made from oxidized cholesterol. The conductance of the phytochrome-modified membrane is increased by red-light illumination but is decreased by illumination with far-red light. Denatured phytochrome does not affect the conductance of the model membrane.
Effects of Adrenal Glucocorticoids on Polyoma Virus Replication
Authors: Morhenn Vera , Rabinowitz Zelig , Tomkins Gordon M.
Published: May 2006

Treatment of polyoma virus-infected fibroblasts from mouse embryos and virus-infected 3T3 cells with physiological concentrations of the glucocorticoids enhances plaque formation at least 10-fold. The data suggest that this effect results from an increased rate of virus production. Steroid specificity studies indicate that the cytoplasmic receptors that mediate the physiological actions of these hormones are also involved in the present effect.
Proposed Tertiary Structure for the Hypothalamic Thyrotropin-Releasing Factor
Authors: Blagdon Douglas E. , Rivier Jean , Goodman Murray
Published: May 2006

Semiempirical energy calculations were performed to determine the conformation of the thyrotropin-releasing factor, L-pyroglutamyl-L-histidyl-L-prolineamide. Our results strongly suggest a “hairpin turn” conformation stabilized by two specific hydrogen bonds. Experimental support for this structure was obtained from proton magnetic resonance by use of chemical shifts and coupling constants with the implied dihedral angles.
Immobilized Catecholamine and Cocaine Effects on Contractility of Cardiac Muscle
Authors: Venter J. Craig , Ross John , Dixon Jack E. , Mayer Steven E. , Kaplan Nathan O.
Published: May 2006

Isoproterenol, norepinephrine, and epinephrine covalently bound to glass beads exert a positive inotropic effect on isometrically contracting papillary muscles from cats. Immobilized isoproterenol maintains increases in force and velocity of contraction for more than 5 hr. 1 μM Cocaine potentiates the action of immobilized norepinephrine, isoproterenol, and epinephrine, but not of isoproterenol in solution. The data presented indicate that the effects of immobilized catecholamines are not due to their coming off the glass. The effects observed with cocaine and immobilized catecholamines are not altered by prior treatment of the muscle with reserpine. These results suggest that the major site of catecholamine action is on receptors located on the extended surface of myocardial cells and a post-junctional site for cocaine potentiation.
Transfer of Genetic Information by Purified Metaphase Chromosomes
Authors: McBride O. Wesley , Ozer Harvey L.
Published: May 2006

Transfer of genetic information from isolated mammalian chromosomes to recipient cells has been demonstrated. Metaphase chromosomes isolated from Chinese hamster fibroblasts were incubated with mouse A
9
cells containing a mutation at the hypoxanthine-guanine phosphoribosyl transferase (
hprt
) locus. Cells were plated in a selective medium, resulting in death of all unaltered parental A
9
cells. However, colonies of cells containing hypoxanthine phosphoribosyl transferase (EC 2.4.2.8) appeared with a variable frequency of about 10
-6
to 10
-7
. The enzyme from these cells was indistinguishable from that from Chinese hamster cells, as shown by DEAE-cellulose chromatography and gel electrophoresis, and differed clearly from the mouse enzyme. The colonies, thus, did not result from reversion of A
9
parental cells to wild type, but appeared to represent progeny of individual cells that had ingested chromosomes, replicated, and expressed the
hprt
gene. These colonies differed from each other in stability of expression of the transferred gene.
Effects of Continuous Noise on Avian Hearing and Vocal Development
Authors: Marler Peter , Konishi Masakazu , Lutjen Ann , Waser Mary Sue
Published: May 2006

Continuous loud noice was used to mask auditory feedback from vocal behavior of male canaries. Single unit techniques demonstrate partial deafness after noise exposure. Longer exposure caused greater deficits, with losses of high-frequency sensitivity. Males raised in noise to 40 days of age, then deafened surgically, thus totally deprived of auditory feedback from vocalization, developed significantly fewer song syllables than birds similarly raised but left intact, to mature in quiet sound-insulated chambers. Males left longer in noise, to sexual maturity at 200 days of age, sang at first like surgically deafend birds, but then increased their song syllable repertoire after noise termination. Thus, in spite of the considerable deafness resulting from noise exposure, the deficit in syllable repertoire was corrected, presumably as a result of restoration of the birds' ability to hear their own song.
Isolation and Characterization of HL-A Variants in Cultured Human Lymphoid Cells
Authors: Pious Donald , Hawley Pamela , Forrest Gary
Published: May 2006

We have developed a procedure for immune selection in an established human lymphoid cell line based on HL-A, the major human histocompatibility locus. After a single brief exposure to selective conditions, HL-A2 variant clones were isolated from an HL-A2/HL-A3 heterozygous line. The variant clones occurred at a frequency of about 1 × 10
-6
. The variant phenotype was stable during prolonged growth in the absence of antiserum after isolation. The variant sublines bound [unk] 1/1000 the HL-A2 antibody per cell as the parent line. Variation was specific in that expression of antigens not selected against was unimpaired. Loss of the chromosome bearing HL-A2 was excluded as the cause of variation because the variants, like the parent line, were heterozygous for phosphoglucomutase (EC 2.7.5.1) determined by structural locus PGM
3
, which is linked to HL-A.
Antigenic Properties of Endogenous Type-C Viruses from Spontaneously Transformed Clones of BALB/3T3
Authors: Aoki Tadao , Todaro George J.
Published: May 2006

During long-term tissue culture of spontaneously transformed clones from BALB/c 3T3 mouse-embryo cells, some clones spontaneously begin to produce high titers of endogenous murine type-C viruses. The antigenic properties of these viruses have been analyzed by indirect immunoelectronmicroscopy and can be classified into two distinguishable populations: (
a
) BALB/c murine myeloma-associated extracellular viruses that carry a specific envelope antigen, xVEA, different from the typical murine leukemia viral envelope antigens; and (
b
) previously uncharacterized type-C viruses that have neither xVEA nor the murine leukemia viral envelope antigens. The former produces PC1 antigen and the latter might induce a new cell-surface antigen. Neither of these two populations of BALB/3T3 endogenous type-C viruses was able to infect BALB/c cells but both could infect NIH Swiss cells. A single BALB/3T3 clone, then, can release infectious endogenous type-C viruses with at least two different antigenic properties. We conclude that BALB/c somatic cells contain preexisting genetic information for production of at least closely related but, nevertheless, distinct type-C viruses.
Immunoferritin Localization of Intracellular Antigens: The Use of Ultracryotomy to Obtain Ultrathin Sections Suitable for Direct Immunoferritin Staining
Authors: Painter Richard G. , Tokuyasu K. T. , Singer S. J.
Published: May 2006

A general method for the ultrastructural localization of intracellular proteins and antigens by immunoferritin techniques has been developed. The method involves direct staining of ultrathin sections of mildly glutaraldehyde-fixed and frozen tissues cut by means of a cryo-ultramicrotome. Bovine pancreatic sections were cut, mounted on grids, and stained with ferritin-rabbit antibovine RNase conjugates. After negative staining with 0.2% phosphotungstic acid, electron micrographs revealed specific labeling of all of the zymogen granules and the cisternae of the rough endoplasmic reticulum. No significant labeling was seen in the nucleus, mitochondria, or cell sap regions. The observation that no significant labeling was found in any region of rat pancreatic sections was consistent with the fact that rat RNase is immunologically non-crossreactive with bovine RNase. In addition, the labeling seen in bovine pancreas was completely absent if the sections were first incubated with free antibody. The method used here avoids prolonged fixation, dehydration, and other harsh chemical or physical treatments, and should extend the usefulness of immunoferritin techniques to the intracellular localization of many protein antigens beyond previously available methods.
Actin in Dividing Cells: Contractile Ring Filaments Bind Heavy Meromyosin
Authors: Schroeder Thomas E.
Published: May 2006

Many microfilaments and microtubules are well preserved after glycerol-extraction of HeLa cells at room temperature (22°). Incubation in heavy meromyosin from rabbit skeletal muscle results in conspicuous and characteristic “decoration” of microfilaments of the contractile ring. Decoration is completely prevented by 10 mM ATP or 2 mM pyrophosphate, and fails to occur if heavy meromyosin is either omitted or replaced by egg albumin, a nonspecific protein. Decorated microfilaments have a substructure consisting of polarized, repeating arrowheads 27-35 nm apart. The specificity of these results strongly suggests that microfilaments of the contractile ring in HeLa cells are closely related to muscle actin. Very thin undecorated strands among the microfilaments of the contractile ring possibly represent a myosin component. These findings are discussed in terms of: the actomyosin-like properties of the contractile ring as a mechanochemical organelle that causes cell cleavage; the probable universal occurrence of actin-like protein in all dividing animal cells; and the contractile ring's combined sensitivity to cytochalasin B and its affinity for heavy meromyosin, a combination unique among microfilamentous organelles.
Cytochalasin Blocks Sympathetic Ganglionic Transmission: A Presynaptic Effect Antagonized by Pyruvate
Authors: Nakazato Y. , Douglas W. W.
Published: May 2006

The mold metabolite cytochalasin B blocked transmission through the perfused superior cervical sympathetic ganglion of the cat. Acetylcholine injected close-arterially during block continued to excite the ganglion cells so that failure was presynaptic and, by inference, due to reduced output of acetylcholine from the preganglionic nerves. This blocking effect of cytochalasin was reduced by pyruvate. It is concluded that cytochalasin inhibits cholinergic nervous function and it does so, at least in part, by depressing energy production at some stage before pyruvate formation. One possibility is a block of glucose uptake for which there is evidence from other cell types. A more general conclusion is that inhibitory effects of cytochalasin on other secretory systems may also involve such a metabolic component and do not necessarily reflect an interaction of the drug with microfilaments as has been commonly supposed.
Activation by Adenosine 3′:5′-Monophosphate of a Membrane-Bound Phosphoprotein Phosphatase from Toad Bladder
Authors: Delorenzo Robert J. , Greengard Paul
Published: May 2006

Adenosine 3′:5′-monophosphate (cyclic AMP) caused a decrease in the net rate of incorporation of radioactive phosphate into a specific protein (protein D) in a membrane fraction from toad bladder. Moreover, when the membrane protein was prelabeled with radioactive phosphate, cyclic AMP caused an increase in the net rate of removal of radioactive phosphate from this specific protein. Certain agents were shown to be selective inhibitors of membrane-bound protein D kinase or protein D phosphatase. With the help of these agents, it was concluded that cyclic AMP caused the activation of membrane-bound protein D phosphatase. The present data, together with earlier studies, are compatible with the possibility that the cyclic AMP-induced activation of a membrane-bound phosphoprotein phosphatase in toad bladder, with the consequent dephosphorylation of protein D, may be responsible for the physiological effects of antidiuretic hormone on sodium and/or water transport in this tissue.
Decreased Globin Messenger RNA in Thalassemia Detected by Molecular Hybridization
Authors: Kacian D. L. , Gambino R. , Dow L. W. , Grossbard E. , Natta C. , Ramirez F. , Spiegelman S. , Marks P. A. , Bank A.
Published: May 2006

In previous studies of patients with β thalassemia, mRNA extracted from reticulocytes in peripheral blood when added to cell-free systems reproduces the deficient β-chain synthesis characteristic of intact cells. The present studies with specific probes for α and β mRNA were designed to decide whether the decreased β mRNA activity is due to the presence of abnormal or reduced β globin mRNA in these cells. Purified α and β complementary DNAs (cDNAs) have been synthesized with RNA-instructed DNA polymerase; α and β mRNAs isolated from heavy (β-producing) and light (α-producing) polyribosomes of rabbit reticulocytes were used as templates. Each of the cDNAs is more than 80% pure by the criterion of biological activity. The α cDNA labeled with [
32
P]dCTP and the β cDNA labeled with [
3
H]dCTP have been added simultaneously to reaction mixtures containing various concentrations of mRNA from thalassemic and nonthalassemic subjects. The extent and rate of hybridization were determined, permitting a comparison of relative α and β mRNA content in the same annealing mixture. In six nonthalassemic patients, relatively equal amounts of hybridizable α and β mRNA appear to be present. In five of seven patients with β-thalassemia, significantly decreased amounts of β mRNA compared to α mRNA can be demonstrated. In two patients with Hemoglobin H disease, there is a decreased amount of α mRNA compared to β mRNA.
Stereospecific Binding of the Potent Narcotic Analgesic [
3
H]Etorphine to Rat-Brain Homogenate
Authors: Simon Eric J. , Hiller Jacob M. , Edelman Irit
Published: May 2006

Etorphine, the most potent narcotic analgesic known, was labeled with tritium by catalytic exchange. This drug exhibits stereospecific, saturable binding to rat-brain homogenate. At saturation, the stereospecific binding is 0.1-0.15 pmol/mg of protein. Specific binding is inhibited high salt concentrations, sulfhydryl reagents, and proteolytic enzymes, but is unaffected by phospholipases A and C, sodium azide, sodium fluoride, and prostaglandins E
1
and E
2
. Competition for binding of [
3
H]etorphine correlates with agonist and antagonist potencies. The stable, stereospecific binding of an active narcotic analgesic supports the existence of opiate receptors.
Conformations of Arsanilazotyrosine-248 Carboxypeptidase A
α,β,γ
. Comparison of Crystals and Solution
Authors: Johansen J. T. , Vallee B. L.
Published: May 2006

The spectra of the α, β, and γ forms of zinc monoarsanilazotyrosine-248 carboxypeptidase A are indistinguishable. At pH 8.2 their crystals are yellow, while their solutions are red, λ
max
510 nm. Absorption and circular dichroism-pH titrations of the modified zinc and apoenzymes demonstrate that the absorption band at 510 nm is due to a complex between arsanilazotyrosine-248 and the active-site zinc atom. Two pK
app
values, 7.7 and 9.5, characterize the formation and dissociation of this arsanilazotyrosine-248·Zn complex. On titrations of the apoenzyme, the absorption band at 510 nm is completely absent at all pH values. Instead, there is a single pK
app
, 9.4, due to the ionization of the azophenol, λ
max
485 nm. Substitution of other metals for zinc results in analogous intramolecular coordination complexes with absorption maxima and circular dichroism extrema characteristic of the particular metal. Similar data and conclusions have been derived from studies of heterocyclic azophenol·metal complexes.

The present studies demonstrate that the conformation of the crystals of all generally available α, β, and γ forms of the arsanilazoenzyme differs from that of their solutions. The spectra of the modified x-ray crystals, however, differ from those of all other carboxypeptidase forms and crystal habits studied. The internal consistency of their data, their interpretation, and the conclusions of Lipscomb and coworkers [
Proc. Nat. Acad. Sci. USA
(1972) 69, 2850-2854] are examined. Dissimilar chemical modification or conformation is thought to underlie these differences.

The arsanilazotyrosine-248·zinc complex is a sensitive, dynamic probe of environmental conditions. Its response to changes in pH and physical state of the enzyme suggest different orientation of the arsanilazotyrosine-248 side chain in solution from that in the crystal. This finding calls for reexamination of the basis of the substrate-induced conformation change which has been thought to be critical to the mechanism, postulated on the basis of the x-ray structure analysis performed at pH 7.5.