bluuebunny/crossref_metadata_2025 huggingface dataset:
BEHAVIOR INDUCTION BY BRAIN EXTRACTS: A COMPARISON OF TWO PROCEDURES
Authors: Rosenblatt Frank
Published: May 2006

Induction of behavior by chemical extracts of trained rat brain has been observed in two types of choice situations. (1) In a symmetric (left/right) choice situation, the induced bias may be either positively or negatively related to that learned by the donors, depending strongly upon dosage and the exact experimental conditions. This makes the effect unstable and difficult to replicate with this procedure. Inversion effects appear to predominate in the observed dosage range. (2) In an asymmetric (two-chamber) choice situation, differing in operant tasks, wall colors, and other cues, a consistently positive effect with a simpler dose dependence was observed. The difference between these two cases is attributed to the lack of specific stimuli identifying the behavioral choices in the symmetric situation, and the abundance of specific stimulus cues in the asymmetric case.
PEPTIDE FORMATION MEDIATED BY HYDROGEN CYANIDE TETRAMER: A POSSIBLE PREBIOTIC PROCESS
Authors: Chang Sherwood , Flores Jose , Ponnamperuma Cyril
Published: May 2006

Chemical evolution on the primitive earth must have involved condensation of α-amino acids to peptides. Under aqueous conditions consistent with current conceptions of primordial waters, heating glycerine with the hydrogen cyanide tetramer, diaminomaleonitrile, yields dipeptide. If nitrogen was cycled through primordial waters as cyanide, peptide synthesis by stepwise tetramer-mediated condensation of α-amino acids would have been a plausible process.
ISOLATION AND PARTIAL CHARACTERIZATION OF A MAJOR INOSITOL-CONTAINING LIPID IN BAKER'S YEAST, MANNOSYL-DIINOSITOL, DIPHOSPHORYL-CERAMIDE
Authors: Steiner S. , Smith Sharron , Waechter C. J. , Lester Robert L.
Published: May 2006

A polar lipid containing about 20 per cent of the lipid soluble inositol has been purified from cells of
Saccharomyces cerevisiae
. This compound labeled with
3
H-inositol,
32
P
i
, or
14
C glucose was isolated from aqueous pyridine extracts by means of paper chromatography. Unlabeled compound was obtained by a differential solubility scheme. Analytical and degradation studies suggest that this compound can be formulated as a mannosyl-diinositol, diphosphoryl-ceramide. It can be converted by treatment with base or acid into a mannosylmonoinositol phosphoryl-ceramide, a composition which relates it to the basic structure of the phytoglycolipids.
SEDIMENTATION EQUILIBRIUM OF POLYDISPERSE NONIDEAL SOLUTES: A COMPARISON OF THREE APPROXIMATIONS
Authors: Deonier Richard C. , Williams J. W.
Published: May 2006

In the evaluation of sedimentation equilibrium data for polydisperse nonideal solutions, extrapolation procedures are required for the determination of the true solute weight-average molecular weight and of the light-scattering second virial coefficient. In an attempt to decide just which concentration-dependent parameter should be used in making these extrapolations, Van Holde and Williams,
J. Polym. Sci.
,
11
, 243 (1953), and Fujita,
J. Phys. Chem.
,
63
, 1326 (1959), and
ibid.
,
73
, 1759(1969), have derived relations between apparent and true weight-average molecular weights which, starting from approximate forms of the same differential equations, appear to give different working expressions. The present analysis of these results will demonstrate new and perhaps unexpected relations between them.

Further, these approximations are discussed in terms of certain of the available experimental data, the purpose being to clarify the conditions under which the behavior of a polydisperse nonideal solution in the ultracentrifuge may be treated as if a nonideal two-component system were involved.
Action of Auxin on Cell Elongation
Authors: Rayle David L. , Evans Michael L. , Hertel Rainer
Published: May 2006

The early time course (0-30 min) of the action of auxin (3-indoleacetic acid) on the elongation of segments from corn coleptiles was studied, using a high-resolution continuous recording technique. Two different effects of auxin were observed: (1) After addition of low auxin concentrations (2 × 10
-7
M
) to 4-mm sections, a very rapid (2-3 min) enhancement of elongation was found. Similar early responses were seen following the addition of low concentrations of the methyl ester of indoleacetic acid. (2) Following a large step-up in the auxin level (10
-5
, 10
-4
, or 10
-3
M
), a rapid transient decrease was observed one to three minutes after the addition of indoleacetic acid. It lasted 10-15 minutes at which time the steady rate of auxin-promoted elongation became evident.

Similar kinetic patterns of auxin effects other than on elongation and the implications of the findings on hypotheses of the primary action of auxin are discussed.
The Conformation of Cholinergic Molecules at Nicotinic Nerve Receptors
Authors: Chothia Cyrus , Pauling Peter
Published: May 2006

A correlation of the crystal structure analyses of the potent nicotinic agonists acetylcholine, acetyl-α-methylcholine, lactoylcholine, 1,1-dimethyl-4-phenylpiperazine, and nicotine allows one to determine the conformation of cholinergic agonists relevant to nicotinic nerve receptors.
Terminal Cross-Linking of DNA Strands by an Enzyme System from
Escherichia coli
Infected with Bacteriophage T4
Authors: Weiss Bernard
Published: May 2006

An enzyme system, purified 560-fold from
Escherichia coli
infected with bacteriophage T4, catalyzes the formation of a phosphodiester bond between the original 5′-phosphoryl end-group of a DNA strand and a 3′-hydroxyl group of the complementary strand. The product, a terminally cross-linked, spontaneously renaturable DNA duplex, has been characterized by chromatographic analysis, by sedimentation analysis, and by enzymatic digestion. Essential components of the enzyme system, which requires both ATP and Mg
++
, include the T4-induced DNA ligase and a component found in extracts of uninfected
E. coli
, which is probably an exonuclease.
Specific Nucleolar and Nucleoplasmic RNA Polymerases
Authors: Roeder Robert G. , Rutter William J.
Published: May 2006

The DNA-dependent RNA polymerase activity present in rat liver nuclei has been solubilized and purified from whole nuclei and from subnuclear fractions. As reported earlier (Roeder, R. G., and W. J. Rutter,
Nature
, 224, 234 (1969)), two major chromatographically distinct enzymatic species (I and II) are present in whole nuclei. Subfractionation of whole nuclei into nucleolar and nucleoplasmic fractions had little effect on the total recovery of activity. Purified nucleoli contain predominantly polymerase I, whereas the nucleoplasmic fraction is greatly enriched for polymerase II. A third minor peak of activity has also been resolved in the nucleoplasmic preparations. We conclude that the RNA polymerases are specifically localized within the nucleus and may, therefore, play specific roles in the regulation of genetic transcription.
DNA Replication in Mammalian Cells, I. The Size of Newly Synthesized Helices
Authors: Nuzzo Fiorella , Brega Agnese , Falaschi Arturo
Published: May 2006

The newly synthesized DNA of heteroploid human cells cultured
in vitro
has a single-stranded molecular weight of approximately 1 × 10
5
following 30- to 60-second pulses of labeling with tritiated thymidine. With increasing pulse times the amount of radioactive DNA having a low single-stranded molecular weight remains approximately constant, whereas increasing amounts of label are found associated with the bulk DNA. After removing the label from the medium, the radioactivity associated with the small molecular weight DNA is chased into high molecular weight material. These findings are analogous to what is observed in microorganisms and suggest a basically common organization of the growing point of DNA in bacterial and in mammalian cells.
Synthetic Spectroscopic Models Related to Coenzymes and Base Pairs, VII. Stacking Interactions in tRNA; the „Bend” at Dimethylguanosine
Authors: Iwamura Hajime , Leonard Nelson J. , Eisinger Josef
Published: May 2006

We have examined the stacking interactions of N
2
-dimethyl-guanosine with the nucleosides, e.g., adenosine and cytidine, found adjacent to it in certain tRNA's, by the use of model compounds in which the trimethylene bridge was substituted for the ribose-phosphate-ribose linkage. From the hypochromism exhibited by synthetic 9-[3-(aden-9-yl)propyl]-2-dimethylaminopurine-6-one (IV) and by 9-[3-(cytos-1-yl)propyl]2-dimethylaminopurin-6-one in aqueous solution (VI) it is appearent that the interaction is at least as great between the N
2
-dimethylguanine moiety and adenine or cytosine as between guanine and these two bases. The fluorescence and phosphorescence emission spectra were obtained in ethylene glycol-water glass at 80°K. The exciplex fluorescence observed for both bi-molecules (IV and VI) containing the N
2
-dimethylguanine unit provides further evidence for stacked chromophores.
Stimulated Formation of Adenosine 3′,5′-Cyclic Phosphate in Cerebral Cortex: Synergism between Electrical Activity and Biogenic Amines
Authors: Shimizu Hirotoshi , Creveling Cyrus R. , Daly John
Published: May 2006

When cortical slices are incubated with adenine-
14
C, adenine nucleotides are labeled in a small and relatively stable pool. The ATP-
14
C of this pool is readily converted to cAMP-
14
C during incubations with depolarizing agents, such as K
+
, ouabain, veratridine, or batrachotoxin. During incubations with these agents, release of acetylcholine and of adenosine into the medium is enhanced. The increase in release of adenosine parallels the enhanced formation of cAMP-
14
C elicited by depolarizing agents, providing further evidence that adenosine may serve to couple electrical activity in the central nervous system with formation of cAMP. When adenosine or a depolarizing agent are incubated, together with a biogenic amine, such as histamine, serotonin, or norepinephrine, the combined effect on cAMP-
14
C formation in cortical slices is much more than additive. Extracellular levels of biogenic amines could in this manner modulate cAMP formation and biochemical responses in nervous tissue during electrical activity.
Biochemical and Genetic Studies of Recombination Proficiency in
Escherichia coli
, I. Enzymatic Activity Associated with
recB
+
and
recC
+
Genes
Authors: Barbour Stephen D. , Clark Alvin J.
Published: May 2006

An adenosine triphosphate-dependent deoxyribonuclease activity has been detected in lysates of
recB
+
recC
+
strains. Mutations in
recB
or
recC
lead to loss of this activity, suggesting that these two genes determine the nuclease activity. The over-all reaction in crude lysates digests native DNA to nucleoside monophosphates. Complementation between
recB21
and
recC22 in vivo
leads to normal levels of ATP-dependent nuclease activity. No complementation
in vitro
has been detected. Mutations in a third recombination gene (
recA
) do not alter significantly the wild-type levels of this nuclease activity.
Cyclic Changes in Thylakoid Membranes of Synchronized
Chlamydomonas reinhardi
Authors: Schor Seth , Siekevitz Philip , Palade George E.
Published: May 2006

Cyclic variations in the activity of photosystems I and II occur during the cell cycle of wild-type
Chlamydomonas reinhardi
. These variations have been localized to chloroplast thylakoid membranes and correlated with corresponding changes in the ratio of chloroplast cytochromes to chlorophyll.
Effect of Lactate on Collagen Proline Hydroxylase Activity in Cultured L-929 Fibroblasts
Authors: Comstock John Paul , Udenfriend Sidney
Published: May 2006

Recent studies with fibroblasts have shown that peptidylhydroxyproline formation begins toward the end of the log phase of growth and is an expression of the activity of the enzyme, collagen proline hydroxylase, which increase in late log-phase cells. This communication reports a two- to fivefold increase in hydroxylase activity on incubating early log-phase cells with lactate. The activation effect is apparently specific for lactate and, although independent of new protein synthesis, requires incubation with intact cells for its expression. Since lactate concentration increases in cells as they normally enter the stationary phase, lactate may play an important role as an activator of one of the collagen-forming enzymes.
Biological Membrane Structure, I. The Protein Crystal Model for Membranes
Authors: Vanderkooi Garret , Green David E.
Published: May 2006

A geometric model for the arrangement of phospholipid and protein in biological membrane systems has been proposed. The essential principle underlying this model is that when membrane proteins polymerize, the points of contact between proteins are few, and cavities lined with predominantly nonpolar amino acids are formed. Phospholipid molecules become oriented with the fatty chains inserted into the cavities while the polar heads remain on the surface of the membrane. This orientation applies to both faces of the membrane continuum. All the lipid known to be present in membranes can be accommodated in this manner. The body of evidence supporting this model has been presented.
Use of Dimethyl Suberimidate, a Cross-Linking Reagent, in Studying the Subunit Structure of Oligomeric Proteins
Authors: Davies Gregg E. , Stark George R.
Published: May 2006

Amidination of aldolase, glyceraldehyde-3-phosphate dehydrogenase, tryptophan synthetase B protein, L-arabinose isomerase, and the catalytic subunit of
E. coli
aspartate transcarbamylase with the bifunctional reagent dimethyl suberimidate produces cross-linked proteins, with reaction predominating within oligomers. Disc electrophoresis of a modified protein on polyacrylamide gel in the presence of sodium dodecyl sulfate resolves a set of species with molecular weights equal to integral multiples of the protomer molecular weight. For oligomers composed of identical protomers, the number of principal species observed is identical to the number of protomers in the oligomer. Application of the method to two proteins composed of dissimilar protomers, native aspartate transcarbamylase and tryptophan synthetase α
2
β
2
complex of
E. coli
, revealed differences in the reactivities of the different kinds of protomer within each oligomer.
Inactivating and Mutagenic Effects of Nitrosoguanidine on Simian Virus 40
Authors: Tegtmeyer Peter , Dohan Curt , Reznikoff Catherine
Published: May 2006

N
-methyl-
N
′-nitro-
N
-nitrosoguanidine (NTG) in high concentrations inactivates extracellular simian virus 40. No mutants were found in stocks of virions partially inactivated by NTG under the experimental conditions employed. In contrast, NTG in low concentrations inhibits the intracellular replication of simian virus 40 and is an effective mutagen of the intracellular virus. Six temperature-sensitive mutants of simian virus 40 have been isolated for genetic studies of the virus and its interaction with mammalian cells.
Age-Specific Selection
Authors: Anderson Wyatt W. , King Charles E.
Published: May 2006

A model is presented for age-specific selection on the genotypes in a population. Each genotype is assigned a life table that specifies the viability and fecundity of its age classes. Breeding and reproduction occur at regular intervals, and generations overlap. Examples were generated on a digital computer. Gene frequencies and the distribution of individuals among the various age classes may oscillate until equilibrium is reached. Moreover, age structure and gene frequencies are intimately related; a change in either factor alone may bring about a change in the other. In an extension of the basic model, the fecundities of the genotypes were regulated by population density. Under the joint action of logistic control and age-specific selection, the growth curve of the population can, for some schedules of selection, show plateaus in an otherwise sigmoid increase. The relevance of the growth patterns obtained in different types of environments to current ideas of „
r
” and „
K
” selection is discussed.
Two Forms of Yeast Glycogen Synthetase and Their Role in Glycogen Accumulation
Authors: Rothman-Denes Lucia B. , Cabib Enrico
Published: May 2006

The glycogen content of yeast rises dramatically just before the onset of the stationary phase of growth. Concomitantly, a rapid increase was found in the glucose 6-phosphate-independent (I) activity of glycogen synthetase, as well as in the total amount of enzyme. A mutant (GS 1-36) was obtained, which did not accumulate glycogen during growth. The synthetase from this strain was in the glucose 6-phosphate-dependent (D) form at all times. The total enzymatic activity of the mutant also increased sharply at the end of the logarithmic phase, although its maximal value was only one third that of the parent strain. Incubation with glucose of wild type resting cells from the logarithmic phase resulted in a slow accumulation of glycogen, which was accelerated after 20 min. At the same time a transformation from the D to I form of the enzyme was detected. The same slow initial rate of glycogen deposition was found with stationary cells of mutant GS 1-36, but the rate gradually declined to zero, rather than accelerating.

The interconversion of the I and D forms was obtained with extracts from cells harvested during different phases of growth. Examination of the properties of the I and D forms showed that the latter was much more strongly inhibited by ATP at low glucose 6-phosphate concentration. These findings clearly establish the fundamental role of the I form in glycogen accumulation. When taken together with previous results, they also show that the physiological significance of the I-D interconversion depends on the concentration of glucose 6-phosphate. Under certain conditions glucsoe 6-phosphate appears to regulate directly the activity of the predominant form of the enzyme.
ACETYLENE REDUCTION ASSAY FOR DETERMINATION OF PHOSPHORUS AVAILABILITY IN WISCONSIN LAKES
Authors: Stewart W. D. P. , Fitzgerald G. P. , Burris R. H.
Published: May 2006

Phosphorus-starved cells of
Anabaena flos-aquae
rapidly increase their capacity to reduce acetylene to ethylene when they receive phosphorus. This response may be used as a bioassay for detecting available phosphorus in aquatic ecosystems. The sensitivity of the method compares favorably with conventional methods for measuring dissolved orthophosphate, and has the additional advantage that it measures available phosphorus. Studies on Wisconsin lakes show that available phosphorus generally is present, that the concentrations are higher at the lower depths than at the surface, and that there may be diurnal variations in the available phosphorus content of surface waters. Important sources of available phosphorus in Lake Mendota are the waters below the thermocline and the input from storm sewers.
ENERGY-COUPLING MECHANISMS IN MITOCHONDRIA: KINETIC, SPECTROSCOPIC, AND THERMODYNAMIC PROPERTIES OF AN ENERGY-TRANSDUCING FORM OF CYTOCHROME
b
Authors: Chance B. , Wilson D. F. , Dutton P. L. , Erecińska M.
Published: May 2006

The primary event of coupled electron transfer at phosphorylation site II is identified with a modification in one of the two chemically distinct forms of cytochrome
b
, designated as the energy-transducing cytochrome
b
T
. This modification is expressed through a change in the redox midpoint potential and by an increase in its reaction half time with cytochrome
c
1
. In pigeon heart mitochondria cytochrome
b
T
exhibits an absorption maximum at 564 nm and on this basis, it can be distinguished from Keilin's cytochrome
b
which exhibits an absorption maximum at 560 nm and serves as an electron carrier on the substrate side of cytochrome
b
T
. Kinetic capability of cytochrome
b
T
is evidenced by its rapid electron transfer and energization time of less than 200 msec, its thermodynamic capability—by a 280 mV potential span suitable for providing one of the two electron transfer reactions required in ATP formation. Two secondary events of coupled electron flow may be identified with a charge separation across the lipid structure of the permeability barrier and a change in water structure; both events result in an increased 1-anilino-8-naphthalene-sulfonic acid (ANS) response to the altered environment.
THE MOLECULAR MECHANISM OF FORCE GENERATION IN STRIATED MUSCLE
Authors: Yu Leepo C. , Dowben Robert M. , Kornacker Karl
Published: May 2006

An electrostatic mechanism for force generation in muscle is proposed which does not require bond formation between thick and thin filaments nor movement of the cross bridges. The myosin heads, which project from the thick filaments and touch the thin filaments, possess a high negative surface charge density. Owing to their large dielectric increment, the thin filaments are polarized by the electric field generated by the myosin heads. The polarized thin filaments tend to move toward the center of the sarcomere. Myosin ATPase activity is increased in the overlap region to maintain the negative surface potential. Thus, ATP hydrolysis provides the energy for shortening. Calculations give estimated tensions generated by this model that are comparable to those observed experimentally for vertebrate striated muscle.
MAPPING OF A HUMAN GENETIC REGULATOR ELEMENT BY SOMATIC CELL GENETIC ANALYSIS
Authors: Klebe Robert J. , Chen Tchaw-ren , Ruddle Frank H.
Published: May 2006

The ES-2 esterase is a kidney-associated esterase and is expressed in a cloned mouse renal adenocarcinoma cell line. Somatic cell hybridization of the mouse renal adenocarcinoma with either mouse or human fibroblasts leads to the marked reduction of ES-2 esterase titer. The extinction of ES-2 esterase activity in mouse×human hybrids is reversible. Extinction correlates with the presence of the human C
10
chromosome in the somatic cell hybrids; whereas reexpression of the ES-2 esterase is observed in hybrids which have lost C
10
. Thus, the proposed regulator element involved is probably structurally linked to C
10
; however, linkage to a member of the D or G groups cannot be completely excluded.
In Vitro
TRANSCRIPTION OF A TRANSFER RNA GENE
Authors: Daniel Violet , Sarid Sara , Beckmann Jacques S. , Littauer Uriel Z.
Published: May 2006

The
Escherichia coli
tRNA
Tyr
gene carried by the ϕ80psu
3
+ transducing phage was transcribed
in vitro
by DNA-dependent RNA polymerase. The enzymatically synthesized tRNA
Tyr
-like polynucleotide chains were detected by competition with purified
E. coli
32
P-tRNA
Tyr
for specific hybridization sites on ϕ80psu
3
+ DNA. Analysis by sucrose gradient centrifugation showed the tRNA
Tyr
-like chains to possess a heterogeneous distribution with respect to sedimentation coefficients, with a broad peak around 8 S. The presence of the termination factor ρ during the transcription did not significantly reduce the average size of the
in vitro
synthesized tRNA
Tyr
-like chains.
Genetically Induced Subcellular Mislocation of
Neurospora
Mitochondrial Malate Dehydrogenase
Authors: Munkres K. D. , Benveniste K. , Gorski J. , Zuiches C. A.
Published: May 2006

Among 60 ultraviolet-induced missense mutations of the structural genes that code for mitochondrial malate dehydrogenase (M-MDH, EC 1.1.1.37) of
Neurospora crassa
, two enzyme phenotypes are observed. In a previously described class (C-mutants), M-MDH is malfunctional because of an abnormal conformation induced by association with mitochondria. We describe here a second class (K-mutants) in which the enzyme is malfunctional because of an altered subcellular location. Thus, although both classes cause lesions in the assimilation of exogenous malate, the nature of the lesions differs. In C-mutants, the enzyme misfunctions because of low affinity for malate but remains mitochondrial-bound as in wild-type. Conversely, K-mutant M-MDH is dispersed throughout the cytoplasm.

Studies of a repressible „glyoxysome” isozyme and a constitutive M-MDH of prototroph and mutants indicate that both isozymes are encoded by the same nuclear structural genes and have polypeptide subunits in common.
Electrophoretic Analysis of Hemoglobin and Isozymes in Individual Vertebrate Cells
Authors: Rosenberg Miriam
Published: May 2006

Electrophoretic patterns of enzymes in single vertebrate erythrocytes may be visualized with the use of capillary tube polyacrylamide columns and stains which amplify the enzymatic activity. The following points have thereby been demonstrated:

1. Peripheral blood of metamorphosing bullfrogs (
Rana catesbeiana
) contains two molecular forms of hemoglobin: embryonic (tadpole) and adult (frog). Only one of these forms is found in each erythrocyte.

2. Human umbilical cord blood contains fetal and adult hemoglobins; both forms may be found in individual erythrocytes, in varying proportions.

3. Both lactate dehydrogenase isozymes found in whole blood of bullfrogs and humans are found in individual erythrocytes, but the proportions differ from cell to cell.
Native Human Parathyroid Hormone: an Immunochemical Investigation
Authors: Arnaud Claude D. , Tsao Hang S. , Oldham Susan B.
Published: May 2006

We have produced an antiserum to porcine parathyroid hormone (PTH) which distinguishes between the PTH in human hyperparathyroid serum and that in extracts of parathyroid adenomata. The PTH secreted into the medium by parathyroid adenoma slices in culture reacts with this antiserum in the same way as the PTH in human hyperparathyroid serum, but extraction of the same serum by a conventional procedure used for the extraction of glandular tissue converts the serum hormone to a species which reacts more like hormone extracted from adenomata. The results suggest that we have immunologically identified a native molecular species of PTH, that the antiserum used recognizes primarily this species in human hyperparathyroid serum, and that the PTH extracted from parathyroid adenomata is immuno-chemically altered.
Phenyldiimide, Hemoglobin, and Heinz Bodies
Authors: Itano Harvey A.
Published: May 2006

Phenylhydrazine is oxidized stoichiometrically by two equivalents of ferricyanide to produce phenyldiimide and ferrocyanide. This reaction permits accurate determination of the absorption maxima and molar absorption coefficients of phenyldiimide in aqueous solution. These values are identical or extremely similar to those of phenyldiimide produced by decarboxylation of phenylazoformic acid. Knowledge of the stoichiometry of the reaction confirms an earlier suggestion that phenyldiimide is the product of ferricyanide-oxidized phenylhydrazine that reacts with heme proteins. Homologous structures postulated for phenyldiimideferrihemoglobin and nitrosobenzeneferrohemoglobin suggest a common factor in the production of Heinz bodies after exposure of erythrocytes to phenylhydrazine and to arylamines.
The Nucleotide Sequence at the 5′-Terminus of the Qβ RNA Minus Strand
Authors: Goodman H. M. , Billeter M. A. , Hindley J. , Weissmann C.
Published: May 2006

The sequence of the first 52 nucleotides at the 5′-end of the Qβ minus strand has been determined and found to be complementary in an antiparallel fashion to the 3′-terminal region of the Qβ plus strand. There are few similarities between the corresponding sequences of Qβ plus and minus strands; however, both have a hydrogen-bonded loop close to the 5′-end. The sequence of the 3′-terminal region of the plus strand was deduced: there are no termination signals within the last 32 nucleotides. A notable homology exists between the 3′-ends of Qβ and R17 RNA.
Detection of Bacteriophage T4- and T5-Coded Transfer RNAs
Authors: Scherberg Neal H. , Weiss Samuel B.
Published: May 2006

A hybridization procedure using mixtures of radioactive aminoacyl-tRNA is described for detecting new phage-induced tRNA species. Five phage-coded tRNA species have been identified from T4 phage infected bacteria and 14 from T5 phage infected cells.
Characterization of RNAs That Do and Do Not Migrate between Cytoplasm and Nucleus
Authors: Goldstein Lester , Trescott Olive H.
Published: May 2006

We have investigated the nature of the RNA that moves from cytoplasm to nucleus against a concentration gradient in
Amoeba proteus
. We find that: In the presence of actinomycin D an unlabeled nucleus grafted into a [
3
H]RNA cytoplasm acquires RNAs with sedimentation constants 30 S, 19 S, and 4-6S that are not related to the general population of cytoplasmic ribosomal and transfer RNAs. RNAs of sedimentation constants 39 S and 16 S may also enter the nucleus from the cytoplasm, but not in the presence of actinomycin D. Nuclei were transplanted from [
3
H]RNA cells through several unlabeled cytoplasms to dilute out migrating [
3
H]RNA. This resulted in the 4-6 S [
3
H]RNA being retained as the predominant labeled material of the nucleus and establishes that a substantial portion of 4-6S nuclear RNA does not leave the interphase nucleus. We conclude that nuclear RNAs may be classified in a new way: (1) RNA that is to become cytoplasmic RNA and presumably moves only from nucleus to cytoplasm; (2) RNA that migrates back and forth between nucleus and cytoplasm; and (3) RNA that does not leave the nucleus during interphase.
Influence of Mercuric Ions on the Phosphorescence and Photochemistry of DNA
Authors: Rahn R. O. , Battista M. D. C. , Landry L. C.
Published: May 2006

Partial mercuration of DNA, such that roughly one mercuric ion is bound for every two thymine residues, results in an enhancement of the phosphorescence by a factor of ten and a small enhancement of the photosteady thymine dimer yield. Complete mercuration of DNA [one Hg(II) added per momoner unit] results in quenching of the phosphorescence intensity and an inhibition of thymine dimer production. The enhancement of the phosphorescence is interpreted in terms of a heavy-atom effect caused by the preferential binding of Hg(II) to the thymine residues. The quenching of both the thymine phosphorescence and the rate of thymine dimerization upon complete mercuration is probably due to energy transfer from thymine to another base, presumably adenine, which when mercurated acts as an energy trap.
Application of the Chloro Ketal Claisen Reaction to the Total Synthesis of Squalene
Authors: Werthemann Lucius , Johnson William S.
Published: May 2006

A short, highly stereoselective (over 97%) synthesis of all-
trans
squalene is described. Starting with succinaldehyde, a tetraenedichlorodione having the complete squalene skeleton with the four internal
trans
olefinic bonds has been developed in four steps involving a sequence of two double Claisen rearrangements. Three simple operations convert this intermediate into squalene.
Development of Insulin-Sensitivity by Mouse Mammary Gland
In Vitro
Authors: Friedberg S. H. , Oka Takami , Topper Yale J.
Published: May 2006

Explants from mammary gland of pregnant mice are sensitive to insulin, but corresponding explants from mature, virgin mice are insensitive to insulin in certain respects. Isolated virgin tissue can acquire insulin-sensitivity independent of exogenous insulin. Some endocrinological and developmental implications are discussed.
Possible Role of Microtubules in Thyroid Secretion
Authors: Williams John A. , Wolff J.
Published: May 2006

Colchicine and other microtubule-active agents have been found to block the release, stimulated by either thyroid-stimulating hormone or by dibutyryl cyclic adenosine 3′:5′-monophosphate, of
131
I from previously
131
I-labeled mouse thyroid glands
in vitro
. The time and concentration characteristics of these inhibitors are consistent with their actions on microtubules in other systems. [
3
H]colchicine was also shown to be bound to a soluble 6S protein of bovine thyroid slices similar to the protein identified in other systems as a microtubular subunit. The demonstrated inhibition of colloid droplet formation and absence of an effect on thyroidal adenyl cyclase or cyclic 3′:5′-phosphodiesterase suggests a colchicine-sensitive role for microtubules in colloid endocytosis in the thyroid gland.
Glycyl-tRNA Synthetase: An Oligomeric Protein Containing Dissimilar Subunits
Authors: Ostrem Dennis L. , Berg Paul
Published: May 2006

Glycyl-tRNA synthetase from
Escherichia coli
is a tetramer containing two small (33,000 daltons) and two large (80,000 daltons) subunits. The subunits can be separated and then reassembled to form active enzyme. Genetically altered glycyl-tRNA synthetases are modified in either the large or the small subunit. Wild type activity can be reconstituted
in vitro
by mixing extracts containing enzymes with modifications in different subunits.
The Carotid Body as a Neuroendocrine Organ Involved in Control of Erythropoiesis
Authors: Tramezzani J. H. , Morita E. , Chiocchio Sara R.
Published: May 2006

The carotid body is generally regarded solely as a chemoreceptor. This paper presents evidence that the carotid body is also an endocrine gland, secreting one or more erythropoiesis-controlling hormones. Its removal is followed by anemia and by a lack of reticulocyte response to daily bleeding.

The removal of both carotid bodies results in a reduction of the high reticulocyte count induced by daily bleeding (5-40% of erythrocytes) down to 0.1% of erythrocytes. The injection of an extract of the carotid body causes reticulocytosis within 5 hr. This reticulocytosis attains its peak 48-72 hr after injection. Daily bleeding for 15 days produces an increase in weight of the carotid body and ultrastructural alterations that indicate increased protein synthesis in the main cells. The injection of plasma from efferent blood from the carotid body into either normal cats or cats from which both carotid bodies have been removed is followed within 6 hr by the appearance of large numbers of reticulocytes and macroreticulocytes in peripheral blood. Carotid body extracts and efferent blood plasma exhibited erythropoietin activity, which was demonstrated in the polycythemic rat by the
59
Fe incorporation method.
Radioimmunoassay of Human Fibrinopeptide A
Authors: Nossel H. L. , Younger L. R. , Wilner G. D. , Procupez T. , Canfield R. E. , Butler V. P.
Published: May 2006

A radioimmunoassay capable of measuring 1 pmole of human fibrinopeptide A has been developed, and should prove useful to detect the release of this peptide from fibrinogen during the coagulation process. Antibodies to fibrinopeptide A were produced by injecting New Zealand white rabbits with a mixture of Freund's adjuvant and native fibrinopeptide coupled to human albumin.
N
-Tyrosyl fibrinopeptide A was synthesized by the solid-phase method, and was iodinated with
125
I by the Chloramine-T method. 48-73% of the radiolabeled peptide could be bound by the serum of a rabbit immunized with the fibrinopeptide-albumin preparation. Antibody-bound peptide was precipitated by dioxane and was thus separated from unbound peptide. The addition of excess native fibrinopeptide to the radiolabeled material prevented its binding to serum. Native fibrinopeptide A and synthetic fibrinopeptide A were identical in their ability to prevent binding, whereas fibrinogen was from 1/25,000 to 1/50,000 as effective on a weight basis. Plasma filtered through a membrane relatively impermeable to molecules larger than a molecular weight of 34,000 showed no fibrinopeptide reactivity, whereas a similar filtrate of serum gave quantitative recovery of fibrinopeptide reactivity.
The Cochlea of the Dolphin,
Tursiops truncatus:
General Morphology
Authors: Wever Ernest Glen , McCormick James G. , Palin Jerry , Ridgway Sam H.
Published: May 2006

The anatomy of the cochlea of the dolphin
Tursiops truncatus
was studied in a number of specimens after fixation by vital perfusion, cellodin embedding, and serial sectioning. The results reveal the general structural relations and cellular detail up to the limits of light microscopy. A description is given of the variations of structure along the course of the cochlea, in which there are many departures from the typical mammalian form, especially in the compact quality of the tissues and the sturdiness of its elements. Apparently these features represent an adaptation of the cetacean ear to the reception of high-frequency sounds.
Selective Associations of Hormonal Steroids with Aminoacyl Transfer RNAs and Control of Protein Synthesis
Authors: Chin Ruei-Chen , Kidson Chev
Published: May 2006

The hormonal steroids progesterone, estradiol, testosterone, and 5α-dihydrotestosterone bind to aminoacyl-tRNA, but not to deacylated tRNA, implying that a change in conformation of tRNA occurs on aminoacylation. Binding is restricted to a few tRNA species and depends on the structure of both tRNA and steroid. There is one binding site per aminoacyl-tRNA molecule, the specificity of which appears to depend on a restricted, single-stranded loop sequence and on the tRNA conformation. By binding to an aminoacyl-tRNA, a steroid can control polypeptide synthesis in a model
in vitro
system by inhibiting chain elongation under conditions where aminoacyl-tRNA concentration is rate-limiting.
Association of H-2 Types with Genetic Control of Immune Responsiveness to IgA Allotypes in the Mouse
Authors: Lieberman Rose , Humphrey William
Published: May 2006

The immune response to BALB/c IgA myeloma proteins (Ir-IgA) was determined in mice of various H-2 types from five different linkage groups of immunoglobulin heavy chains (IgC
H
). Antisera were examined for antibodies to idiotypic (Fab) and allotypic (Fc) specificities. No immune response to IgA myeloma proteins was found in mice with the same linkage group as BALB/c but with different
H-2
alleles. In mice with immunoglobulin heavy chains that are different than BALB/c, a high immune response to IgA myeloma proteins was found in H-2 types a, k, r, and s; a low response is associated with H-2
b
and H-2
d
types. Chromosome mapping of
Ir-IgA
genes in the
H-2
locus indicate that they are on the right side of the chromosome, to the right of the
Ss
locus.
Ir-IgA
genes are controlled by dominant autosomal genes.
Imaginal Disc Abnormalities in Lethal Mutants of
Drosophila
Authors: Shearn Allen , Rice Thomas , Garen Alan , Gehring Walter
Published: May 2006

Late lethal mutants of
Drosophila melanogaster
, dying after the larval stage of development, were isolated. The homozygous mutant larvae were examined for abnormal imaginal disc morphology, and the discs were injected into normal larval hosts to test their capacities to differentiate into adult structures. In about half of the mutants analyzed, disc abnormalities were found. Included among the abnormalities were missing discs, small discs incapable of differentiating, morphologically normal discs with limited capacities for differentiation, and discs with homeotic transformations. In some mutants all discs were affected, and in others only certain discs. The most extreme abnormal phenotype is a class of “discless” mutants. The viability of these mutant larvae indicates that the discs are essential only for the development of an adult and not of a larva. The late lethals are therefore a major source of mutants for studying the genetic control of disc formation.
Irreversible Inhibition of Biotin Transport in Yeast by Biotinyl-
p
-nitrophenyl Ester
Authors: Becker Jeffrey M. , Wilchek Meir , Katchalski Ephraim
Published: May 2006

Biotinyl-
p
-nitrophenyl ester (BNP), an active-ester derivative of biotin, irreversibly inactivates biotin transport in the yeast
Saccharomyces cerevisiae
. Transport inactivation is progressive with time and occurs at concentrations of the ester as low as 10
-7
M. In the presence of sodium azide, a reagent known to block biotin accumulation in yeast, the derivative is still effective. The specificity of inactivation by the ester is revealed by the following findings: (
a
) Biotinyl-
p
-nitroanilide and acetyl-
p
-nitrophenyl ester do not affect biotin transport; (
b
) the nitrophenyl ester does not affect the transport of lysine and aspartic acid, or that of L-sorbose; (
c
) inactivation of biotin transport by the ester is partially prevented when the cells are incubated with it in the presence of relatively high concentrations of biotin.
The Sequential Unfolding of Ribonuclease A: Detection of a Fast Initial Phase in the Kinetics of Unfolding
Authors: Tsong T. Y. , Baldwin R. L. , Elson E. L.
Published: May 2006

Temperature-jump studies have been used to detect a rapid reaction in the thermal unfolding of ribonuclease A (RNase A). The fast reaction occurs over a wide range of pH, and the results of a detailed study at pH 1.3 are reported here. Although its amplitude is small, the reaction is easily measurable over the entire temperature range of thermal unfolding. It occurs in the millisecond time range, and is faster by 3-4 orders of magnitude than the slow unfolding reaction studied previously. Unfolding is measured here by the change in absorbance at 287 nm, which reflects the exposure to solvent of buried tyrosine groups. Since the fast reaction has a detectable amplitude only in the temperature range of unfolding, it apparently detects the presence of intermediate, partly-folded states. Previous equilibrium studies of the unfolding of RNase A in the pH range 1-2 have indicated that it is essentially a 2-state reaction, without detectable intermediates.

The existence of a rapid transient phase in the unfolding of RNase A had been predicted previously from a model for this unfolding reaction, based on nucleation-dependent sequential folding. The model served to reconcile kinetic and equilibrium studies of the thermal unfolding reaction of RNase A at neutral pH. Kinetic studies had shown that the slow unfolding reaction, measured at 287 nm, could be represented as a single exponential process, as expected for a 2-state reaction. However, earlier equilibrium measurements, especially the calorimetric studies of Sturtevant and coworkers, had revealed significant deviations from the 2-state behavior at neutral pH. These conflicting observations are explained by the model, which satisfies closely many criteria for a 2-state unfolding, even when appreciable concentrations of partly folded molecules are present. In particular, it predicts that the final, and major, portion of the kinetic reaction will occur as a single process characterized by an exponential time course.
The Cochlea of the Dolphin,
Tursiops truncatus:
Hair Cells and Ganglion Cells
Authors: Wever Ernest Glen , Mccormick James G. , Palin Jerry , Ridgway Sam H.
Published: May 2006

A study of the cochlear hair cells in
Tursiops truncatus
showed 3451 inner and 13,933 outer hair cells, for a total of 17,384. This total is of the same order of magnitude as the value of 14,975 for the human ear. Determination of the ganglion cell population for the dolphin gave a total of 95,004 cells, which is about three times as many as in man.

The large number of hair cells in the dolphin ear suggests a high order of auditory proficiency in general, and especially a marked ability of tonal differentiation. The large ratio of ganglion cells to hair cells suggests unusual capabilities in the utilization of auditory information.
Restrictions of Sequence on the Thickness of Globular Protein Molecules
Authors: Gates Ronald E. , Fisher Harvey F.
Published: May 2006

A model for globular protein molecules based on a linear and random sequence of polar and nonpolar amino acids was developed. Polar amino acids were assumed to be always in contact with the aqueous solvent, while nonpolar amino acids were assumed to have a tendency to be buried. Considerations of amino-acid dimensions indicated that only runs of four or more nonpolar amino acids in a row could allow some amino acids to be more than 1-nm (10-Å) removed from the surface of the protein. The expected volume fraction of a protein molecule that could be more than 1-nm removed from the surface was obtained with the assumption of a random sequence. Calculation of this volume fraction for a number of simple geometric shapes indicated that some nonpolar amino acids must be exposed to solvent and that the maximum average thickness of globular proteins should be 3-4 nm. Good agreement with published protein dimensions was obtained.
Structure of the Replicating DNA from Bacteriophage T4
Authors: Delius Hajo , Howe Chin , Kozinski Andrzej W.
Published: May 2006

At an early stage of replication, parental T4 DNA shows a loop structure often displaying two 3′-ended, single-stranded “whiskers”, located in
trans
configuration at the branching-points. Several such loops have been observed within a single T4 molecule. Occasionally, reinitiation occurred in the middle of a loop, which suggests that the loop was growing in both directions.
Genetics of Somatic Mammalian Cells: Lethal Antigens as Genetic Markers for Study of Human Linkage Groups
Authors: Puck Theodore T. , Wuthier Paul , Jones Carol , Kao Fa-Ten
Published: May 2006

The antigen that causes killing of at least 98% of a human cell population treated with a 1% solution of a specific rabbit antiserum in the presence of complement is a sensitive genetic marker. The rapid loss of human chromosomes in human-Chinese hamster cell hybrids makes possible a convenient test of linkage relationships with this marker. Hybrid clones with and without the lethal antigen were isolated and analyzed. In 76 clones and subclones studied, 41 carried both the lethal antigen and the lactic dehydrogenase-A marker, 35 carried neither, and no clones contained only one of the two markers. In contrast to this clear demonstration of linkage, absence of linkage was found between the lethal antigen and the following markers: Lactic dehydrogenase B, NAD-dependent malic dehydrogenase, NADP-dependent malic dehydrogenase, glucose-6-phosphate dehydrogenase, phosphoglucomutase, glutamate oxaloacetate transaminase, indophenol oxidase, glucose phosphate isomerase, proline, inositol, hypoxanthine B, and glycine A. This lethal antigen appears to be carried on a single human autosome.
Localized Mutagenesis of Any Specific Small Region of the Bacterial Chromosome
Authors: Hong Jen-Shiang , Ames Bruce N.
Published: May 2006

A method, which we call
localized mutagenesis
, is described for the isolation of temperature-sensitive and other types of mutations in any specific small region (about 1%) of the bacterial chromosome. The principle of this method is to mutate the transducing DNA rather than the bacterial DNA. One can select for the introduction of this mutated DNA into any particular region of the bacterial chromosome by transducing an auxotrophic marker in that region to prototrophy, thereby introducing new mutations in the neighborhood. We have used this method to isolate many different temperature-sensitive mutations in genes of unknown function in particular regions of the chromosome. Since the method is very simple, it can be used to saturate any region of the map with mutations in essential genes, or for various types of genetic manipulations. Although we have used hydroxylamine-mutagenized phage P22 and
Salmonella typhimurium
, the method should be applicable to other mutagens and bacteria and transducing phage.
Hydrolysis of fMet-tRNA by Peptidyl Transferase
Authors: Caskey C. T. , Beaudet A. L. , Scolnick E. M. , Rosman M.
Published: May 2006

Escherichia coli
and rabbit reticulocyte (f[
3
H]Met-tRNA·AUG·ribosome) intermediates undergo hydrolysis, with release of f[
3
H]methionine, upon addition of tRNA or CpCpA in the presence of acetone. This ribosomal catalyzed reaction has similar requirements, pH optimum, and antibiotic sensitivity to those of peptidyl transferase. Two antibiotics, lincomycin with
E. coli
ribosomes and anisomycin with reticulocyte ribosomes, inhibit peptide-bond formation and transesterification activities of peptidyl transferase, but stimulate hydrolysis of f[
3
H]Met-tRNA. Earlier studies have suggested peptidyl transferase activity is essential for R factor-dependent hydrolysis of f(
3
H)Met-tRNA. These studies indicate that peptidyl transferase has the capacity for f(
3
H)Met-tRNA hydrolysis and, therefore, may be responsible for peptidyl-tRNA cleavage during peptide chain termination.