bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlamydomonas reinhardtii cell preparation with altered permeability toward substrates of organellar reactions.
Authors: Belknap W R , Togasaki R K
Published: May 2006

Chlamydomonas reinhardtii cells disrupted under low pressure in a Yeda press yielded a preparation ("presate") with high permeability toward substrates for Class A chloroplasts and intact mitochondria. The stoichiometric rates of CO2 uptake and O2 photoevolution by the wild-type cell pressate were severely suppressed by 10 mM exogenous phosphate, and this suppression could be reversed by the addition of either 3-phosphoglycerate or dihydroxyacetone phosphate. A mutant, F60, which lacks phosphoribulokinase activity and hence CO2-dependent O2 photoevolution, was studied by using intact cells, pressate, and sonicated pressate. In the pressate, the rate of 3-phosphoglycerate-dependent O2 photoevolution was high, whereas that dependent on K3Fe(CN)6 was low; the opposite was true of the sonicated pressate. p-Benzoquinone supported high rates of O2 evolution in both the pressate and the sonicated pressate. The slow O2 uptake in the dark by the dark-adapted wild-type pressate could be increased by the addition of succinate and further stimulated by ADP. Addition of KCN resulted in rapid but only partial suppression of this activity. Dark O2 uptake by the unpressed preparation did not show similar responses. The procedure described here opens the possibility of in situ analysis of Class A chloroplasts from wild-type and mutant strains of C. reinhardtii.
Individual recognition and learning of queen odors by worker honeybees
Authors: Breed Michael D.
Published: May 2006

A honeybee queen is usually attacked if she is placed among the workers of a colony other than her own. This rejection occurs even if environmental sources of odor, such as food, water, and genetic origin of the workers, are kept constant in laboratory conditions. The genetic similarity of queens determines how similar their recognition characteristics are; inbred sister queens were accepted in 35% of exchanges, outbred sister queens in 12%, and nonsister queens in 0%. Carbon dioxide narcosis results in worker honeybees accepting nonnestmate queens. A learning curve is presented, showing the time after narcosis required by workers to learn to recognize a new queen. In contrast, worker transfers result in only a small percentage of the workers being rejected. The reason for the difference between queens and workers may be because of worker and queen recognition cues having different sources.
A 40-Hz auditory potential recorded from the human scalp.
Authors: Galambos R , Makeig S , Talmachoff P J
Published: May 2006

Computer techniques readily extract from the brainwaves an orderly sequence of brain potentials locked in time to sound stimuli. The potentials that appear 8 to 80 msec after the stimulus resemble 3 or 4 cycles of a 40-Hz sine wave; we show here that these waves combined to form a single, stable, composite wave when the sounds are repeated at rates around 40 per sec. This phenomenon, the 40-Hz event-related potential (ERP), displays several properties of theoretical and practical interest. First, it reportedly disappears with surgical anesthesia, and it resembles similar phenomena in the visual and olfactory system, facts which suggest that adequate processing of sensory information may require cyclical brain events in the 30- to 50-Hz range. Second, latency and amplitude measurements on the 40-Hz ERP indicate it may contain useful information on the number and basilar membrane location of the auditory nerve fibers a given tone excites. Third, the response is present at sound intensities very close to normal adult thresholds for the audiometric frequencies, a fact that could have application in clinical hearing testing.
Erythrosomes: large proteoliposomes derived from crosslinked human erythrocyte cytoskeletons and exogenous lipid.
Authors: Cuppoletti J , Mayhew E , Zobel C R , Jung C Y
Published: May 2006

Large (3-micrometers diameter) mechanically stable proteoliposomes (erythrosomes) were prepared in good yield by coating crosslinked erythrocyte cytoskeletons with phosphatidylcholine. The erythrosomes consist of the polypeptides designated band 1, 2, 3, 4.1 + 4.2, and 5 (less than 4% of the endogenous lipid) and enough added lipid to form a bilayer coating the surface. Electron microscopy shows only the large proteoliposomes in sealed preparations. The trapping of bovine serum albumin, mannitol, sucrose, glucose, cytosine arabinoside, and sodium in the erythrosomes was demonstrated, yielding an apparent volume of up to 100 liters/mol of phospholipid. This preparation possesses an effective diffusion barrier to glucose, sucrose, and sodium ion with half-equilibration times of 34, 29, and 170 hr, respectively. The results of the present study suggest that erythrosomes may be useful for membrane transport protein reconstitution and encapsulation systems.
On the molecular basis of transition mutations: frequencies of forming 2-aminopurine.cytosine and adenine.cytosine base mispairs in vitro.
Authors: Watanabe S M , Goodman M F
Published: May 2006

We address the question of whether substituting 2-aminopurine (APur) in place of adenine (Ade) in DNA can increase the frequency of base mispairing with cytosine. Using DNA polymerase alpha to measure the rates of inserting deoxycytidine and thymidine nucleotides in direct competition with each other for APur or Ade sites on synthetic copolymer DNA templates, we observe that the ratio of dCMP to dTMP insertion is increased by a factor of at least 230 when APur replaces Ade on a poly(dA) template and by a factor of 35 when APur replaces Ade on a poly(dC,dA) template. These data support the idea that APur.C base mispairs are directly involved in APur induction of A.T leads to G.C transition mutations. The observed misinsertion frequency of cytosine substituting for thymine opposite template APur sites is about 5%. This value is in excellent agreement with earlier predictions and measurements for APur.C heteroduplex-heterozygote frequencies in T4 bacteriophage in vivo.
Methylmercury(II) binding to single-stranded and duplex DNA: complexes formed are distinguishable by optical detection of magnetic resonance spectroscopy.
Authors: Maki A H , Ott C M
Published: May 2006

Binding of CH3Hg(II) to duplex and single-stranded calf thymus DNA leads to an external heavy atom effect that is associated with the formation of complexes directly with the purine and pyrimidine bases. When CH3Hg(II) is added at a concentration insufficient to cause denaturation, clearly distinguishable optical detection of magnetic resonance spectra are observed from the duplex and single-stranded DNA complexes. Comparison of the dominant signals with those observed from CH3Hg(II) complexes of model mononucleotides and mononucleosides allows their identification as guanine complexed at N7 in the duplex sample and thymine complexed at N3 in the single-stranded sample. On the basis of these measurements, it is estimated that this experiment presently is capable of detecting about 2% single-stranded DNA in a sample made up predominantly after duplex structure.
Regulation of synthesis of cell-specific ribosomal proteins during differentiation of
Dictyostelium discoideum
Authors: Ramagopal Subbanaidu , Ennis Herbert L.
Published: May 2006

Proteins of ribosomes from various stages of development in
Dictyostelium discoideum
were analyzed by two-dimensional polyacrylamide gel electrophoresis. Significant changes in protein composition were observed; the data demonstrate that cell differentiation in a eukaryotic system is accompanied by ribosome heterogeneity. Both qualitative and quantitative differences were noted for 12 unique ribosomal proteins between the vegetative amoebae and spores (differentiated cells). Two proteins were specific to ribosomes of amoebae, and three were specific to spores. The others were common to both cells but showed characteristic stoichiometric changes. The appearance and quantitative changes of these proteins were associated with specific stages of cell differentiation and were evident only during the aggregation phase; however, further changes continued through construction of fruiting bodies. As functional mRNAs for all 12 proteins were present in both amoebae and spores, both transcriptional and translational mechanisms apparently regulate the synthesis of the various developmentally controlled ribosomal proteins in the two cell types.
Is there a difference among human populations in the rate with which mutation produces electrophoretic variants?
Authors: Neel J V , Rothman E
Published: May 2006

Data are summarized that suggest that tropical-zone/tribal/nonindustrialized populations have higher frequencies of certain types of protein variants than temperate-zone/civilized/industrial populations, and it is demonstrated that these differences are not an artifact produced by the contagious type of sampling used with respect to tribal populations. Evidence is reviewed that suggests that a possible explanation of this difference is higher mutation rates in the tribal populations studied.
Control of liver 6-phosphofructokinase by fructose 2,6-bisphosphate and other effectors.
Authors: Van Schaftingen E , Jett M F , Hue L , Hers H G
Published: May 2006

Rat liver 6-phosphofructokinase (ATP-D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) was partially purified free of interfering enzymes by a rapid procedure. Fructose 2,6-bisphosphate, at micromolar concentrations, greatly stimulated the enzyme by increasing its affinity for fructose 6-phosphate and relieving the inhibition by ATP. Its action was synergistic with that of AMP. As a stimulator of liver phosphofructokinase, fructose 2,6-bisphosphate was approximately 1000- and 2500-fold more efficient than fructose 1,6-bisphosphate and glucose 1,6-bisphosphate, respectively. The concentration at which a half-maximal effect was obtained with the hexose bisphosphates was dependent upon the experimental conditions. It was relatively high at physiological concentrations of substrates, AMP, and Pi, and under these conditions the positive effect of fructose 1,6-bisphosphate was no longer detectable. This was probably due to the negative effect of fructose 1,6-bisphosphate as a reaction product inhibitor. It is concluded that fructose 2,6-bisphosphate rather than fructose 1,6-bisphosphate controls, in association with other effectors, the activity of phosphofructokinase in the liver.
Anesthetics and high-pressure interaction upon elastic properties of a polymer membrane.
Authors: Kamaya H , Suezaki Y , Ueda I , Eyring H
Published: May 2006

Anesthetics expand cell membranes, and high pressures (about 10-15 MPa) antagonize the anesthetic action. It is also known that inhalation anesthetics expand elastomer membranes. The mechanism of pressure antagonism of anesthetic action on membrane expansion was investigated in the present study with Silastic membranes. Halothane increased the length of Silastic membrane (0.14% per kPa), with an accompanying decrease of Young's modulus (3.7.10(5) Newton/m2 per kPa). High pressure decreased the length of the membrane and increased Young's modulus. The magnitudes of the pressure effect on the length and Young's modulus of the Silastic membrane in the presence of the anesthetic were not identical with those observed in the absence of the anesthetic. In the presence of halothane at pressures common to clinical applications, the bulk modulus of the membrane decreased about 4.6-4.0%. These results suggest that the effects of pressure and anesthetic upon the elastomer may not be completely independent of each other.
Resonance Raman investigation of dioxygen bonding in oxycobaltmyoglobin and oxycobalthemoglobin: structural implication of splittings of the bound O--O stretching vibration.
Authors: Tsubaki M , Yu N T
Published: May 2006

Splittings related to the stretching vibration of bound dioxygen in hemoproteins have been detected by resonance Raman spectroscopy. With excitation at 406.7 nm we observe three isotope-sensitive lines in oxycobaltmyoglobin (oxyCoMb) [or in oxycobalthemoglobin A (oxyCoHbA)] at 1103 (1107), 1137 (1137), and 1153 (1152) cm-1, of which the most intense one appears at 1137 cm-1. The first two frequencies arise from resonance interaction between a v(O--O) mode at approximately 1122 cm-1 and an accidentally degenerate porphyrin ring mode at 1123 (1121) cm-1, whereas the third one represents an "unperturbed" v(O--O) vibration from a different species. These two v(O--O) modes at approximately 1122 and approximately 1153 cm-1 shift to approximately 1066 and approximately 1096 cm-1, respectively, upon 16O2 leads to 18O2 substitution. The same resonance interaction may also occur in oxyFeMb (probably also in oxyFeHb(a), because it exhibits an intensity increase at 1125 cm-1 upon 16O2 leads to 18O2 substitution, although the v(O--O) vibrations have not been observed directly. Concomitant enhancement is observed in the v(Co--O) vibration at 539 (537( cm-1, which is considerably lower than the v(Fe--O) frequency at approximately 570 cm-1 in oxyFeMb and oxyFeHbA. The Co--O bond is longer and weaker than the Fe--O bond. Enhancement of both v(O--O) and v(Co--O) indicates the existence of a charge-transfer transition underlying the Soret band, which may be assigned as pi*(pi g*O2/xz) leads to sigma*(dz2Co/pi g*). The presence of two v(O--O) vibrations (at approximately 1122 and approximately 1152 cm-1) but only one v(Co--O) mode at approximately 538 cm-1) means that the two species in oxyCoMB or oxyCoHbA have the same Co--O bond lengths but different O--O bond lengths. The bound dioxygen in a bent end-on configuration may have two allowed orientations, which differ in the extent of sp2(N epsilon) leads to pi*(O2) donation from distal histidine.
Adipogenic and anti-adipogenic factors in the pituitary and other organs.
Authors: Hayashi I , Nixon T , Morikawa M , Green H
Published: May 2006

Adipose conversion of cultured 3T3 cells is known to depend on an adipogenic factor present in serum. In the presence of this factor, extracts of different organs were found to inhibit the adipose conversion. The most active extracts were derived from brain, uterus, and pituitary, but other organs also possessed appreciable activity. Fibroblast growth factor partially purified from both brain and pituitary was much more active in suppressing adipose conversion than were crude extracts of the corresponding organs. Purified platelet-derived growth factor was also an effective inhibitor. Of all the tissue extracts tested, only pituitary possessed, in addition to the inhibitory activity, an adipogenic factor similar to that demonstrated previously in serum. This was revealed at concentrations of extract too low for the inhibitory factor to be effective. Under these conditions the pituitary extract had a specific adipogenic activity orders of magnitude higher than that of serum. We suggest that the adipogenic factor of serum may originate in the pituitary.
Mediation of retinal photoisomerization by adduct formation with tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)-europium(II).
Authors: Ellis A B , Schreiner R , Ulkus R A
Published: May 2006

Several retinal isomers are shown to form adducts in isooctane solution with a lanthanide beta-diketonate complex, tris(6,6,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III) [Eu(fod)3]. The adducts are characterized by an absorption band whose lambda max at approximately 420 nm is red-shifted by approximately 60 nm from the lowest-energy absorption band in the free retinal isomers. Irradiation into this adduct band leads to photoisomerization. For example, photolysis of a 1 mM all-trans-retinal/3 mM Eu(fod)3 isooctane solution at 514.5 nm leads, with reasonable quantum efficiency (phi greater than or equal to 0.05), to isomeric mixtures that are considerably different from these produced with UV excitation in the absence of Eu(fod)3. Particularly noteworthy for a photolysis conducted in a nonpolar solvent is the presence of an appreciable quantity of 11-cis-retinal in the adduct photolysate.
Sharp local bounds for orders of contact
Authors: D'Angelo John P.
Published: May 2006

I outline a proof of the sharp local bound for a jump discontinuity in the maximum order of contact of complex analytic varieties with a real hypersurface. This involves a new algebraic-geometric approach to questions arising in the study of the Cauchy-Riemann equations.
On irregularities of distribution of real sequences
Authors: Chung F. R. K. , Graham R. L.
Published: May 2006

A natural measure of the amount of unavoidable clustering that must occur in any bounded infinite sequence of real numbers is studied. We determine the extreme value for this measure and exhibit sequences that achieve this value.
Monoclonal antibody to aflatoxin B1-modified DNA detected by enzyme immunoassay.
Authors: Haugen A , Groopman J D , Hsu I C , Goodrich G R , Wogan G N , Harris C C
Published: May 2006

Monoclonal antibodies were obtained after fusion of mouse P3 X 63 myeloma cells with spleen cells isolated from BALB/c mice that had been immunized with aflatoxin B1-adducted DNA complexed with methylated bovine serum albumin. Selected hybridomas were found to produce monoclonal antibodies specific for aflatoxin B1-modified DNA containing both the 2,3-dihydro-2-(N7-guanyl)-3-hydroxyaflatoxin B1 and the putative 2,3-dihydro-2-(N5-formyl-2',5',6'-triamino-4'oxo-N5-pyrimidyl) -3-hydroxyaflatoxin B1, suggesting that these DNA adducts share a common antigenic determinant. The monoclonal antibody was not reactive towards the free aflatoxin B1-guanine adducts in solution, seven other aflatoxin derivatives, or benzo[a]pyrene-adducted DNA. A noncompetitive ultrasensitive enzyme radioimmunoassay could measure 15 fmol of aflatoxin B1-DNA adducts in 10 ng of DNA and was at least 100-fold more sensitive than the standard enzyme-linked immunosorbent assay. Competitive enzyme-linked immunosorbent assay with these monoclonal antibodies reliably quantitated aflatoxin B1 adducted in vivo to rat liver DNA at adduct levels of one aflatoxin B1 residue per 250,000 nucleotides. The competitive ultrasensitive enzyme radioimmunoassay was determined to be at least 6-fold more sensitive than the competitive enzyme-linked immunosorbent assay in analysis of aflatoxin B1-adducted DNA. Therefore, enzyme immunoassay using monoclonal antibodies will be useful analytical tools for studying both the molecular interactions of aflatoxin B1 with DNA and the occurrence of aflatoxin B1-DNA adducts in biological specimens from people exposed to this environmental carcinogen.
Molecular cloning and partial characterization of unintegrated linear DNA from gibbon ape leukemia virus.
Authors: Scott M L , McKereghan K , Kaplan H S , Fry K E
Published: May 2006

We have cloned the complete genome of an oncogenic primate retrovirus, the San Francisco isolate of gibbon ape leukemia virus, in a lambda phage vector. DNA sequence analysis and restriction endonuclease mapping of the inserted linear provirus demonstrated 9-base pair inverted repeats at its ends, flanking direct terminal repeats 470 base pairs in length. The (-) strong stop region of this DNA showed surprisingly low sequence homology to that of another gibbon ape leukemia virus isolate from an animal with similar disease. Analysis of the clone also revealed the terminal phosphate configuration of the linear provirus. The recombinant phage is suitable for direct use as a hybridization probe to detect homologous retroviral sequences in human cell lines.
Metabolic conversion of dibenz[a,h]anthracene (+/-)trans-1,2-dihydrodiol and chrysene (+/-)trans-3,4-dihydrodiol to vicinal dihydrodiol epoxides.
Authors: Chou M W , Fu P P , Yang S K
Published: May 2006

The hydroxyl groups of dibenz[a,h]anthracene trans-1,2-dihydrodiol and chrysene trans-3,4-dihydrodiol are known to be predominantly in quasi-axial conformations. These dihydrodiols were metabolized by liver microsomes from 3-methylcholanthrene-pretreated rats to form 1,2,3,4-tetrahydrotetrols as the major products. The major metabolites of the dihydrodiols were isolated by reversed-phase high-performance liquid chromatography and identified by ultraviolet--visible absorption and mass spectral analyses. The results indicate that axial hydroxyl groups of dibenz[a,h]anthracene trans-1,2-dihydrodiol and of chrysene trans-3,4-dihydrodiol do not direct metabolism away from their respective vicinal double bond.
Reciprocity or near-reciprocity of highly coupled enzymatic processes at the multidimensional inflection point.
Authors: Caplan S R
Published: May 2006

It has recently been demonstrated that coupled enzymatic processes may possess, for a particular choice of the state variables, multidimensional inflection points in thermodynamic force-flow space. The conditions for reciprocity in the linear region near such a reference state, which may be far from equilibrium, are of considerable interest. It is shown by examining the associated Hill diagrams that all cycles in which a given pair of forces act contribute a corresponding pair of symmetrical terms to the Jacobian matrix characterizing perturbations about this stationary state. To the extent that these cycles dominate--i.e., to the extent that the system is highly coupled--reciprocity or near-reciprocity will be obeyed. This would be expected to be the case in most biological systems.
Differential expression of crown gall tumor markers in transformants obtained after
in vitro Agrobacterium tumefaciens
-induced transformation of cell wall regenerating protoplasts derived from
Nicotiana tabacum
Authors: Wullems George J. , Molendijk Lucy , Ooms Gert , Schilperoort Robbert A.
Published: May 2006

To obtain transformation of plant cells, we incubated 3-day-old cell wall-regenerating protoplasts from tobacco with
Agrobacterium tumefaciens
harboring tumor-inducing plasmids. Putative transformed tobacco cells were selected by phytohormone autotrophic growth and were shown to be transformed by the detection of the tumor cell specific enzymes lysopine dehydrogenase or nopaline dehydrogenase. This was substantiated by the detection, in transformed tumor tissues, of DNA sequences homologous to sequences in the tumor-inducing plasmid. Segregation of tumor markers has been observed among the transformants and it is suggested that this happened during the initiation of the transformation. The stable character of the transformed state was shown by the retention of tumor markers in subcloning of primary transformants under nonselective conditions. Suppression of the neoplastic state of transformants could take place, resulting in the development of transformed shoots. Indications were obtained for the inheritance of tumor markers through meiosis from seedlings obtained from seeds of flowering transformed plants that still expressed nopaline synthesis.
Biological activity of cloned retroviral DNA in microinjected cells.
Authors: Kopchick J J , Ju G , Skalka A M , Stacey D W
Published: May 2006

Avian retroviral DNA molecules that had been cloned from infected cells by using recombinant DNA techniques were microinjected into either uninfected chicken embryo fibroblasts (CEF) or CEF transformed by the envelope glycoprotein-deficient Bryan strain of Rous sarcoma virus [RSV(--)cells]. Retroviral DNA injected into RSV(--) cells directed transcription of envelope mRNA, which was then able to complement the RSV(--) env deficiency and promote the production of infectious transforming virus. The retroviral DNA also directed the production of fully infectious virus after injection into uninfected cells or RSV(--) cells. Virus production began within 3--4 hr after microinjections. When 100 DNA molecules per cell were injected, almost all injected cells produced infectious virus. As the number of injected molecules per cell was decreased, a corresponding decrease was observed in the number of cells that produced infectious virus. DNA injected into the cytoplasm was 1/50th to 1/10th as effective in virus production as DNA molecules injected into the nucleus. DNA molecules containing one or two tandem copies of the viral long terminal repeat were equally effective in virus production.
Genes, individuals, and kin selection
Authors: Darlington Philip J.
Published: May 2006

The altruistic-gene theory of kin selection requires conditions so improbable that its reality is doubtful. The gene-quantity theory, including the theory of inclusive fitness, assumes that selection acts on sums of kins' genes, but no effective mechanism is apparent. Insect and human societies may have evolved by individual selection, in two steps: first something made staying together advantageous to individuals, and then altruistic behaviors evolved in net-gain lotteries, also (statistically) advantageous to individuals. Kin selection is not required in these or any other unequivocal cases; the theory should be reexamined and probably abandoned. The probability of kin selection is further reduced by the cost of evolution by selection. Much current evolutionary mathematics and determinist sociobiology, which ignore how the cost of selection limits the precision of adaptations, including adaptive behaviors, may be dangerously unrealistic.
Structural analysis of a new B-cell-differentiation antigen associated with products of the I-A subregion of the H-2 complex.
Authors: Huber B T , Jones P P , Thorley-Lawson D
Published: May 2006

Ia.W39 is a private specificity of the I-Ab subregion of the H-2 complex. It is selectively expressed on a subset of B lymphocytes that is absent in newborn normal and adult mutant mice carrying the xid gene. Immunoprecipitation and one-dimensional NaDodSO4/polyacrylamide gel electrophoresis showed that the molecule bearing Ia.W39 consists of two noncovalently linked glycoproteins of apparent Mr 33,000 and 28,000. Anti-Ia.W39 serum did not preclear the Iab molecule; however, the conventional allo-anti-I-Ab serum cleared Ia.W39 completely. In view of the identical two-dimensional gel pattern generated by the Ia.W39 and the conventional Iab immunoprecipitates, we believe that all Ia molecules bear the conventional specificities and only a subset would in addition express Ia.W39. Ia.W39 is probably not a carbohydrate antigen, because the antibiotic tunicamycin had no influence on its expression. It may be a conformational determinant on the A alpha and A beta complex induced by the association of an unknown molecule with these chains.
Role of cysteine in regulating morphogenesis and mitochondrial activity in the dimorphic fungus Histoplasma capsulatum.
Authors: Maresca B , Lambowitz A M , Kumar V B , Grant G A , Kobayashi G S , Medoff G
Published: May 2006

Three stages can be distinguished in the temperature-induced mycelial-to-yeast phase transition of Histoplasma capsulatum. Stage one is characterized by a progressive decrease in the respiration rate and in the intracellular concentrations of cysteine and other amino acids. By stage two, respiration has ceased completely and free cysteine has fallen to low levels. Exogenous cysteine is required during the second stage for activation of mitochondrial respiration (stage three) and completion of the morphological transition. Mitochondria isolated from cells in the second stage show no respiration with NADH, succinate, or other substrates unless they are first incubated with cysteine. In addition, a novel, cytosolic cysteine oxidase appears during the latter part of the second stage. In stage three, the respiration rate rises, intracellular concentrations of free cysteine and other amino acids increase to levels characteristic of yeast, and the morphological transition is completed. The results support the idea that alterations in cysteine metabolism play a key role in this differentiation process.
Some isometric embedding and rigidity results for Riemannian manifolds
Authors: Berger Eric , Bryant Robert , Griffiths Phillip
Published: May 2006

In this note, we announce some new results concerning rigidity and isometric embeddings of Riemannian manifolds. A special case of the main result states that a general

M
n

[unk]

R
n+r

,
r
≤(
n
- 1)(
n
- 2)/2, is uniquely determined up to finitely many constants by its induced
ds
2
.
Purification of human eosinophil-derived neurotoxin.
Authors: Durack D T , Ackerman S J , Loegering D A , Gleich G J
Published: May 2006

Human and animal eosinophils contain a powerful neurotoxin that causes selective neuronal and axonal damage to white matter of cerebellum and spinal cord of experimental animals when injected intrathecally. This reaction is termed the "Gordon phenomenon." We purified the eosinophil-derived neurotoxin from eosinophil-rich leukocyte suspensions or eosinophil granules from four patients with various hypereosinophilic syndromes. A single protein with an average molecular weight of 18,400 was isolated by sequential chromatography on Sephadex G-50 columns and analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis of column fractions. The purified eosinophil-derived neurotoxin from the cells of these patients retained the potent neurotoxic activity of the crude eosinophil or eosinophil granule extracts in experimental animals. These animals developed the syndrome of stiffness and ataxia progressing to severe paralysis characteristic of the Gordon phenomenon. Histologic examination of the brains of animals injected with purified eosinophil-derived neurotoxin confirmed the characteristic widespread loss of Purkinje cells and severe spongiform vacuolation in the white matter of cerebellum, brain stem, and spinal cord. We have established the location of eosinophil-derived neurotoxin in the eosinophil granule and have shown that it is distinct from several other eosinophil proteins, the granule major basic protein, and the Charcot-Leyden crystal protein (lysophospholipase).
Subcellular localization and secretion of factor V from human platelets.
Authors: Chesney C M , Pifer D , Colman R W
Published: May 2006

Factor V, a plasma protein cofactor necessary for optimal conversion of prothrombin to thrombin, is also present in considerable concentration in blood platelets (9.9 units per 10(9) platelets). Subcellular fractionation by two methods has localized factor V in the alpha granules of unstimulated platelets. ADP and epinephrine cause release of 4.6% and 6.4%, respectively, of the total factor V, a process completely inhibited by cyclooxygenase alkylation by aspirin. In contrast, collagen causes release of 25% of platelet factor V, a process only partially suppressed by aspirin. Secretion of factor V depends on the availability of metabolic energy, because antimycin A, an inhibitor of aerobic metabolism, and 2-deoxyglucose, an inhibitor of anaerobic glycolysis, together almost totally inhibited the secretion of factor V induced by collagen. The data establish that factor V is not normally available on unstimulated platelets but can be secreted from alpha granules upon stimulation with physiological agents such as ADP, epinephrine, and collagen. Because factor V is known to serve as a receptor for factor Xa, the exposure of factor V on platelets consequent to release would accelerate the process of blood coagulation.
Representation of weakly harmonizable processes
Authors: Rao M. M.
Published: May 2006

Weakly harmonizable processes are represented by a family of positive definite contractive linear operators in a Hilbert space. This generalizes the known result on weakly stationary processes involving a unitary family. A characterization of the vector Fourier integral of a measure on R → [unk], a reflexive space, is given, and this yields another characterization of weakly harmonizable processes when [unk] is a Hilbert space. Also these processes are shown to have associated spectra, yielding a positive solution to a problem of Rozanov.
Glitches and pinned vorticity in the Crab pulsar
Authors: Alpar M. A. , Anderson P. W. , Pines D. , Shaham J.
Published: May 2006

We suggest that the glitch behavior observed in the Crab pulsar is associated with vorticity jumps induced by a starquake or a comparable external fluctuation in the weakly pinned vortex region expected in the crust of a young neutron star, and that the differences in the glitch behavior of the Crab, Vela, and older pulsars may be explained on evolutionary grounds.
Functional expression in primate cells of cloned DNA coding for the hemagglutinin surface glycoprotein of influenza virus.
Authors: Sveda M M , Lai C J
Published: May 2006

We have used simian virus 40 (SV40) DNA as a vector for expression of functional activity of a cloned influenza viral DNA segment in primate cells. Cloned full-length DNA sequences coding for the hemagglutinin of influenza A virus (Udorn/72/[H3N2]) were inserted into the late region of a viable deletion mutant of SV40, and the hybrid DNA was propagated in the presence of an early SV40 mutant (tsA28) helper. Infection of primate cells with the hybrid virus produced a polypeptide similar in molecular size to the hemagglutinin of influenza virus, as shown by immunoprecipitation and gel electrophoresis. The polypeptide was glycosylated, as shown by incorporation of radioactive sugars. The putative hemagglutinin exhibited functional activity, as shown by agglutination of erythrocytes. In addition, an indirect immunofluorescence assay showed that the hemagglutinin polypeptide of the hybrid virus could be detected on the surface of infected cells.
Is acquired immunological tolerance genetically transmissible?
Authors: Nisbet-Brown E , Wegmann T G
Published: May 2006

We have attempted to verify that acquired characteristics can be transmitted through the male germ line by using as a model system the vertical transmission of specific immunological tolerance to major histocompatibility antigens. Tolerant males were a tetraparental mouse and separated parabionts, in each case showing stable lymphoid chimerism. Tolerance in the progeny was assessed by two in vivo assays, rejection of cardiac allografts and clearance of 131I-labeled tumor cells. We were unable to find evidence for heritability of the tolerant state in tetraparental or parabiont males, with either assay system.
Pleiotropic expression of Epstein--Barr virus DNA in human epithelial cells.
Authors: Stoerker J , Parris D , Yajima Y , Glaser R
Published: May 2006

We have attempted to establish a system that can be used to study the association of Epstein--Barr virus (EBV) with epithelial cells. Attempts were made to transfect human carcinoma cells with EBV DNA. Successful transfection was confirmed by the expression of EBV-specific early antigen (EA), virus capsid antigen, and the presence of virus DNA. The transfecting preparation contained a mixture of EBV and cellular DNA extracted from two producer cell lines, P3HR-1 and AG-876. Our data suggest that virus DNA obtained from the P3HR-1 nontransforming, EA-inducing strain of EBV was lytically expressed in the epithelial tumor cells. The DNA derived from AG-876 cells, which produce a transforming, non-EA-inducing strain of EBV, also produced a lytic infection.
Direct demonstration of a correspondence between the dopamine islands and acetylcholinesterase patches in the developing striatum.
Authors: Graybiel A M , Pickel V M , Joh T H , Reis D J , Ragsdale C W
Published: May 2006

The distribution of dopamine-containing processes in the striatum of fetal and neonatal cats was studied by immunohistochemical and glyoxylic acid histofluorescence methods and compared to the distribution of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) observed by thiocholine histochemistry in the same or serially adjoining sections. Both methods for demonstrating the dopamine innervation revealed the characteristic patchwork of dopamine "islands" in the caudoputamen, in which catecholamine histofluorescence or tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2]-like immunoreactivity was concentrated into 0.2- to 0.6-mm-wide patches. Both methods also demonstrated a high degree of patterning of the dopamine innervation in the ventral striatum, including the nucleus accumbens septi. A detailed and striking match was found between these configurations and the compartmental distribution of acetylcholinesterase observed in the caudoputamen and ventral striatum of the same brains. The correspondence between the dopamine and acetylcholinesterase figures was most obvious in the fetal brains, in which the background acetylcholinesterase staining was lightest, but matches between the dopamine islands and acetylcholinesterase patches could still be seen in the kittens. There was no clear alignment of striatal cell bodies stained for acetylcholinesterase with either the dopamine or the acetylcholinesterase-positive patches. Nor was there an obvious correspondence between dopamine and acetylcholinesterase in the striatal background matrix. We conclude that, at least during ontogenesis, it is the clustered arrangements of dopamine and acetylcholinesterase that are, in particular, tightly linked, and we suggest that information about the maturation of these clusters may be crucial in assessing the functions of striatal dopamine and acetylcholinesterase in the adult.
Unique plasmid-like mitochondrial DNAs from indigenous maize races of Latin America
Authors: Weissinger A. K. , Timothy D. H. , Levings C. S. , Hu W. W. L. , Goodman M. M.
Published: May 2006

Mitochondrial DNA from 81 races of Latin American maize were examined by agarose gel electrophoresis. Twelve South American races each contained two plasmid-like mtDNA molecules similar to those of the cytoplasmic male-sterile S type (
cms
-S). The plasmid-like elements from all 12 races, designated RU, appear to be identical. Both molecules appear
in vitro
as double-stranded linear DNAs terminated by repeated sequences arranged in reverse polarity (terminal inverted repeats). The larger molecule of the pair, R-1, contains about 7460 nucleotides. It shares considerable homology with the larger plasmid-like molecule of
cms
-S, S-1, but is about 1000 nucleotides longer than S-1, has a unique sequence of about 2576 nucleotides, and also contains a
Bam
HI recognition site not present in S-1, R-2, the smaller plasmid-like element, consists of about 5450 nucleotides and appears to share complete homology with S-2, the smaller plasmid-like molecule of
cms
-S. Neither pollen sterility nor any other trait has been associated with the R-1 and R-2 plasmid-like mtDNAs. The
Bam
HI restriction fragments of total mtDNA from the 12 RU cytoplasms display similar patterns, which differ only slightly but vividly from that of a normal maize standard, B73 × Mo17.
Bam
HI restriction analysis of 22 additional races produced arrays similar to those of the RU cytoplasms, but which lacked plasmid-like mtDNAs. The taxonomic significance of this digestion pattern and of the RU cytoplasms is discussed. One Mexican race, Conico Norteño, has been shown to contain the
cms
-S cytoplasm.
Immunocytochemical localization of tubulin, actin, and myosin in axonemes of ciliated cells from quail oviduct.
Authors: Sandoz D , Gounon P , Karsenti E , Sauron M E
Published: May 2006

Tubulin, actin, and myosin have been localized in isolated demembranated ciliated cells from quail oviduct by immunocytochemistry in both light and electron microscopy by using purified antibodies. The peripheral doublets and the central tubules are stained by the antitubulin whereas the kinetosomes are poorly stained. Actin antibodies clearly stain the axonemes, but only on the proximal-half portion, whereas myosin antibodies stain a small area of the axonemes just above the ciliary neck region.
Calcium alters the sensitivity of intact horizontal cells to dopamine antagonists.
Authors: Van Buskirk R , Dowling J E
Published: May 2006

Horizontal cells of the carp retina possess dopamine receptors linked to adenylate cyclase. Isolated, intact horizontal cells respond to micromolar concentrations of dopamine, whereas nanomolar concentrations of haloperidol, (+)-butaclamol, and flupenthixol block the dopamine response. Preincubation in Ringer's solution containing increased levels of Ca2+ (5-110 mM) decreases the sensitivity of the cells to these antagonists by 1,000-10,000 times. Dopamine sensitivity of the cells is not affected by Ca2+ levels in the preincubation medium. Preincubation of the cells in Ringer's solution containing 500 microM L-glutamate, an agent that increases intracellular Ca2+ levels in intact horizontal cells, also decreases the sensitivity of the cells to haloperidol. These data suggest that antagonist sensitivity of intact horizontal cells may be regulated by intracellular Ca2+.
Periodic explosions by positive feedback in a rising foam column
Authors: Zener Clarence , Noriega Jaime
Published: May 2006

An aqueous foam rising adiabatically in a column suffers a drop in temperature. Under appropriate conditions, such a column periodically explodes. We here trace this explosion to the tight thermal coupling between the foam and its enclosing glass column. When the surface surfactant concentration is unbuffered by micelles, a positive feedback exists between the flow of heat from the walls into the foam and the thermal conductivity of the foam itself. In our highly expanded foam, heat is conducted through the foam cells' interior primarily by the heat-pipe effect. Such an effect is retarded by a dense layer of surfactant molecules. Heat absorption causes cell expansion, which, in a foam unbuffered by micelles, causes a reduction in surface concentration of surfactant molecules and, hence, in an increase in thermal conductivity. This interpretation of our observed periodic explosions is in agreement with all of our observations.
Immersions of manifolds
Authors: Cohen Ralph L.
Published: May 2006

This paper outlines a proof of the conjecture that every compact, differentiable,
n
-dimensional manifold immerses in Euclidean space of dimension 2
n
- α(
n
), where α(
n
) is the number of ones in the dyadic expansion of
n
.
Ethidium bromide changes the nuclease-sensitive DNA binding sites of the antitumor drug cis-diamminedichloroplatinum(II).
Authors: Tullius T D , Lippard S J
Published: May 2006

Exonuclease III has been shown previously to reveal the binding sites of the antitumor drug cis-diamminedichloroplatinum(II) on DNA. Pretreatment of the same DNA with the intercalator ethidium bromide causes new platinum binding sites to be detected by the exonuclease III method. In particular, a 5'd(G6-D-G2)3' sequence in a 165-base-pair restriction fragment of plasmid pBR322 becomes a preferred site for exonuclease III-detectable cis-diamminedichloroplatinum(II)binding. This switching of nuclease-sensitive platinum binding to new sites by the influence of another drug, ethidium bromide, offers an explantation at the molecular level for the phenomenon of synergism in combination chemotherapy.
Cytochrome c oxidase inhibition by anesthetics: thermodynamic analysis.
Authors: Vanderkooi G , Chazotte B
Published: May 2006

The thermodynamic parameters that characterize the inhibition of cytochrome c oxidase activity, in rat liver submitochondrial particles, by n-butanol, tetracaine, and dibucaine were obtained. Three equilibria were assumed in order to account for the data: for the interaction of inhibitor with the native state of the enzyme, for the interaction of inhibitor with the thermally (reversibly) denatured state, and for the change between the native and thermally denatured states. Inhibition results from interaction with both the native and denatured states but, because the interaction is stronger with the denatured than with the native state, the native/denatured equilibrium is shifted to the right by the anesthetics. The enthalpies of interaction are -2.3, -4.7, and 3.7 kcal/mol (1 cal = 4.18 J) for the native state and -10, -6, and -14 kcal/mol for the denatured state, for n-butanol, tetracaine, and dibucaine, respectively. These values are much smaller than the previous estimates obtained by using the assumption that anesthetics interact only with the thermally denatured state of enzymes (e.g., -81 kcal/mol for tetracaine inhibition of luciferase). Our results suggest that local anesthetics inhibit enzyme activity by causing a reversible perturbation of protein conformation. The magnitude of the perturbation is much smaller (in energetic terms) than that which accompanies thermal denaturation.
Proteins associated with poly(A)+RNA of cockerel liver: effects of estradiol stimulation.
Authors: Johnson T R , Ilan J
Published: May 2006

The protein population of poly(A)-containing messenger ribonucleoprotein (mRNP) from cockerel liver was analyzed before and after estradiol induction. Polysomal and free mRNP were isolated by thermal elution from oligo(dT)-cellulose. The proteins were separated by two-dimensional electrophoresis (of which the first dimension was a nonequilibrium pH gradient) and were visualized by silver staining. In order to determine similarities and differences between proteins of various mRNP fractions, trace amounts of 125I-labeled protein from one fraction were coelectrophoresed with stainable amounts of protein from another fraction on the same gel. Of 27 proteins analyzed, 15 were common to polysomal and free mRNP, 7 were specific to polysomal mRNP, and 5 were specific to free mRNP. Moreover, estradiol strongly influenced 11 proteins. Six proteins changed either in relative intensity or in distribution between polysomal and free mRNP fractions. Three major proteins appeared in both fractions, and two additional proteins disappeared from the free mRNP fraction after estradiol treatment. The results suggest that the protein population in polysomal mRNP is quite complex and that the profound influence of estradiol on protein synthesis in cockerel liver may be connected to changes in the protein composition of mRNP.
Expression of Thy-1 antigen is not limited to T cells in cultures of mouse hemopoietic cells.
Authors: Schrader J W , Battye F , Scollay R
Published: May 2006

Large numbers of Thy-1-positive cells were observed in cultures of bone marrow cells that had been depleted of T cells and grown for 3 to 4 days in the presence of medium conditioned by concanavalin A-activated spleen cells. Cells bearing levels of Thy-1 comparable with those on the bulk of thymocytes were isolated by using the fluorescence-activated cell sorter. Although many were large blasts, the Thy-1-positive cells failed to grow in response to T-cell growth factor and concanavalin A; about one-third, however, proliferated in the presence of factors stimulating hemopoietic progenitor cells. Furthermore, the Thy-1-positive population included cells capable of forming large colonies of macrophages and granulocytes in agar and cells forming splenic colonies in lethally irradiated mice. The appearance of the Thy-1-positive cells did not correlate with the presence of either T-cell growth factor or T-cell-derived granulocyte/macrophage colony-stimulating factor. These findings indicate that Thy-1 can occur on various murine hemopoietic stem and progenitor cells and myeloid cells; Thy-1 can no longer be regarded as an unambiguous marker of commitment to the T-cell lineage.