bluuebunny/crossref_metadata_2025 huggingface dataset:
Segregation of Functional Sex Factor into Minicells
Authors: Kass Leon R. , Yarmolinsky Michael B.
Published: May 2006

The segregation of a bacterial plasmid, the sex factor F′, has been investigated in a cell-division mutant of
Escherichia coli
which produces small anucleate cells (minicells). Significant amounts of isotopically labeled DNA segregate into minicells dependent upon the presence of F′. Minicells containing F′Gal or F′(λ) are shown to donate the plasmid in conjugation. These results demonstrate that the sex factor may be dissociated from the bacterial chromosome and that this separation does not prevent its subsequent transfer.
Synthesis and Secretion of γ-Globulin by Lymph Node Cells, VIII. Order of Synthesis of the Interchain Disulfide Linkages of Immunoglobulins
Authors: Sutherland Earl W. , Zimmerman Daniel H. , Kern Milton
Published: May 2006

Murine myeloma cells (ADJ-PC-5), incubated
in vitro
with
3
H-leucine, secrete
3
H-immunoglobulin G as a single molecular species as judged by the migration characteristics of the labeled product on sodium dodecyl sulfateacrylamide gel electrophoresis. However, the fact that some of the interchain disulfide linkages of intracellular immunoglobulins had not been acquired permitted the identification of the following intracellular species: LHHL (identical to immunoglobulin G), HHL, HH, and L (H and L refer to heavy and light polypeptide chains, respectively). Although HH and HHL were readily observed, radioactivity was not detected in the region of the gel where HL would be expected. The time course for the appearance of the intermediates indicates that in these cells the first interchain disulfide bond to be formed occurs between heavy chains. In contrast, the interchain disulfide bonds of immunoglobulins derived from rabbit lymph node cells were acquired in a different order. The principal intracellular species observed were LHHL and HL, whereas HHL and HH were not detectable. These findings indicate that in this species the first interchain disulfide bond to be formed is that between the heavy and light chains of immunoglobulin G.
AXON GROWTH: ROLES OF MICROFILAMENTS AND MICROTUBULES
Authors: Yamada Kenneth M. , Spooner Brian S. , Wessells Norman K.
Published: May 2006

The motile tips of elongating axons consist of growth cones from which microspikes protrude. Cytochalasin B causes retraction of microspikes, rounding-up of growth cones, and cessation of axon elongation. Drug withdrawal is followed by resumption of growth cone and microspike activity and of axon elongation. In contrast, colchicine causes shortening and retraction of axons, but it does not initially affect the tips. Growth cones and microspikes of elongating axons contain a network of 50 Å microfilaments, the pattern of which is altered by cytochalasin treatment. These experiments indicate that both structural integrity of the axon and continuing function of its motile tip are essential elements in axonal elongation.
Symmetric Replication of the
Bacillus subtilis
Chromosome
Authors: Quinn William G. , Sueoka Noboru
Published: May 2006

Synchronously replicating chromosomes in germinating spores of
Bacillus subtilis
were labeled near the origin with [
3
H]bromouracil. The label appeared in heavy-light DNA. When cell growth and chromosome replication were continued in unlabeled bromouracil, nearly all the tritium label was transferred to heavy-heavy DNA while the terminus remained unreplicated. This implies that both origins of the replicating chromosome can undergo reinitiation. Therefore, during multifork replication the chromosome takes on the symmetric „dichotomous” form rather than the asymmetric configuration predicted by the rolling circle model.
A Lesson from the Smog Capital of the World
Authors: Haagen-Smit A. J.
Published: May 2006

The history of air pollution control in the Los Angeles area shows a gradual transfer of authority from city and county to state and federal government. The relative role of the various levels of government is discussed. Regional control will become increasingly important with standards set or approved by state and federal authorities. Progress is noted in the control of both stationary and moving sources, but long-range planning of the development of our urban complex with an overriding regard for its effect on the environment is needed if the technological innovations are to keep pace with the demands of an ever-increasing population.
Seryl-tRNA in Mammalian Tissues: Chromatographic Differences in Brain and Liver and a Specific Response to the Codon, UGA
Authors: Hatfield Dolph , Portugal Franklin H.
Published: May 2006

Differences in the elution profiles of seryl-tRNAs of beef and of rabbit liver and brain were observed. A species of beef seryl-tRNA obtained by reversed phase column chromatography that responds specifically to the codon UGA was found. In addition, a species of rabbit and of chicken seryl-tRNA that recognizes UGA was found.
Modification of Histones during Spermiogenesis in Trout: A Molecular Mechanism for Altering Histone Binding to DNA
Authors: Sung Michael T. , Dixon Gordon H.
Published: May 2006

At a late stage of spermatogenesis in rainbow-trout testis, the entire complement of histones is replaced by newly synthesized protamine and histones are extensively phosphorylated and acetylated. Tryptic digestion of purified histones labeled by incubation of testicular cells with [
32
P]phosphate shows that phosphorylation occurs at a small number of seryl residues.

Histone I (lysine-rich) is phosphorylated in the sequence Lys-Ser(PO
4
)-Pro-Lys, which is located in the lysine-rich C-terminal region of the molecule. Histones IIb
1
(slightly lysine-rich) and IV (glycine, arginine-rich) give rise to the same phosphopeptide, Ac-Ser(PO
4
)-Gly-Arg, which comprises the amino terminus of each histone. Thermolysin digests of phosphohistones IIb
1
and IV also released a phosphopeptide with composition corresponding to the first six residues of histone IV: Ac-Ser(PO
4
)-Gly-Arg-Gly-Lys-Gly. An α-helical model of the N-terminal region of histone IV shows that this region is a possible DNA-binding site. Phosphorylation at serine 1 together with ε-amino acetylation at lysines 5, 8, 12, and 16 (observed in histone IV from trout testis) could profoundly modify ionic interactions and lead to an „unzipping” of histone IV from DNA
On the State of the Iron and the Nature of the Ligand in Oxyhemoglobin
Authors: Wittenberg Jonathan B. , Wittenberg Beatrice A. , Peisach J. , Blumberg W. E.
Published: May 2006

The structure of the oxygenated heme group of oxyhemoglobin may be formulated as [Hb(Heme d
1/2
5
)·OO
-
]. The heme iron atom is formally ferric, and the ligand is bound superoxide anion. When deoxyhemoglobin combines reversibly with oxygen a partial transfer of an electron occurs from the ferrous iron atom to the oxygen molecule. By surrendering its electron the iron atom has become ferric; in accepting an electron the ligated oxygen molecule has become a new species, the bound superoxide anion (·OO
-
).

The configuration of the heme iron atom is deduced from comparison of the optical spectrum in the visible region of oxyhemoglobin with that of alkaline ferric hemoglobin whose configuration is established by electron paramagnetic resonance spectroscopy. The configuration of both species is low spin ferric heme iron (Heme d
1/2
5
). The configuration of the ligated oxygen molecule of oxyhemoglobin is not accessible to study by magnetic or optical probes. However it may be known by analogy with the configuration of the ligated oxygen molecule of reversibly oxygenated cobalt complexes whose structure has been proved by both electron paramagnetic resonance and x-ray diffraction analysis. It is bound superoxide anion (·OO
-
). Other physical studies bearing on the structure of the oxygenated heme group are discussed. Reasons are given for believing that the proposed formulation of the oxyhemoglobin structure is consistent with the known stability of oxyhemoglobin.
Temperature-Sensitive Mutations of the Photosynthetic Apparatus of
Rhodospirillum rubum
Authors: Weaver Paul
Published: May 2006

Temperature-sensitive mutants of
Rhodospirillum rubum
have been isolated by enrichment techniques selecting for conditionally aberrant electron flow in various portions of the electron transport scheme. The temperature sensitivity of a class of these strains is shown to preferentially affect the photosynthetic mode of growth and energy production over the aerobic mode.
Prediction of RNA Secondary Structure
Authors: Delisi Charles , Crothers Donald M.
Published: May 2006

Calculations of the free energy required to close single-strand loops by formation of a base pair in double-helical nucleic acids are reported. These results can be used to estimate the free energy of particular secondary structures for a given RNA molecule under conditions of high-salt concentration.
Specific Binding of Peroxidase-Labeled Myelin Basic Protein in Allergic Encephalomyelitis
Authors: Johnson Anne B. , Wiśniewski Henryk M. , Raine Cedric S. , Eylar E. H. , Terry Robert D.
Published: May 2006

A conjugate of horseradish peroxidase and the encephalitogenic basic protein from myelin has been used to study the antigen reactivity of tissue in the autoimmune disease, experimental allergic encephalomyelitis. Control conjugates were also prepared of peroxidase and bovine serum albumin and of peroxidase and lysozyme, another basic protein. The basic protein from myelin conjugate was specifically bound by lymph node cells from rabbits immunized against the basic protein. Some of these cells appeared to be plasma cells. The conjugate was also specifically bound by occasional cells in the spinal-cord infiltrates of animals with early signs of allergic encephalomyelitis. These cells resembled large lymphocytes and plasma cells. There was no difference between the binding of basic protein of bovine and rabbit origin. The findings suggest the possibility that a local release of antibody within the target organ may play a role in the pathogenesis of allergic encephalomyelitis.
Anti-Antibody Activity of a Monoclonal Macroglobulin
Authors: Warner Noel L. , Mackenzie Malcolm R. , Fudenberg H. Hugh
Published: May 2006

A monoclonal macroglobulin from a patient with Waldenström macroglobulinemia has been shown to have antiglobulin activity of a new type, namely, that of a true anti-antibody. The protein reacts with human, primate, and rabbit IgM and IgG, only when the target immunoglobulin is complexed to an antigen. The implications of the general findings of antiglobulin activity of monoclonal proteins is discussed in relation to the possible etiology of the disease.
Modulation of Glutamine Synthetase Adenylylation and Deadenylylation Is Mediated by Metabolic Transformation of the P
II
-Regulatory Protein
Authors: Brown M. S. , Segal A. , Stadtman E. R.
Published: May 2006

Earlier studies showed that two protein components, P
I
and P
II
, are concerned with the adenylylation and deadenylylation of
Escherichia coli
glutamine synthetase (EC 6.3.1.2). P
I
by itself catalyzes both adenylylation and deadenylylation, but its activity is modulated by the P
II
-protein and by glutamine, 2-oxoglutarate, ATP, and UTP, The P
II
-protein exists in two forms: one form, P
II
-AT, stimulates P
I
-catalyzed adenylylation activity in the absence of glutamine and makes this activity very sensitive to inhibition by 2-oxoglutarate; it does not affect deadenylylation activity. The other form, P
II
-DA, stimulates adenylylation only if glutamine is present, and also stimulates the deadenylylation activity of P
I
, which is then dependent upon the presence of ATP and 2-oxoglutarate. Conversion of P
II
-AT to P
II
-DA requires the presence of UTP, ATP, and 2-oxoglutarate; it is catalyzed by an enzyme present in P
I
preparations. UTP may be directly involved in this conversion since P
II
-DA fractions reisolated by filtration through Sephadex G-100 contain small quantities of a bound uridine derivative that lacks the γ-phosphoryl group of UTP. The activity of P
II
-DA, but not of P
II
-AT, is destroyed by treatment with snake-venom phosphodiesterase. ATP and 2-oxoglutarate apparently function as allosteric effectors for the conversion of P
II
-AT to P
I
-DA.
An
Escherichia coli
Mutant with Increased Messenger Ribonuclease Activity
Authors: Lennette Evelyne T. , Gorelic Lester , Apirion David
Published: May 2006

A temperature-sensitive mutant strain of
Escherichia coli
exhibits a remarkable increase in RNase activity when grown at its nonpermissive temperature. During growth at the nonpermissive temperature, there is an increase in the extent of breakdown of pulse-labeled RNA and a decrease in the functional lifetime of the mRNA for the
lac
operon. T7 RNA, which is usually stable in
E. coli
, is also stable in this strain at the nonpermissive temperature. It is possible that the RNase measured is part of the normal mechanism of mRNA degradation in the cell. A mechanism for mRNA degradation that requires the combined action of endonuclease(s) and 3′ to 5′ exonuclease(s) is proposed.
Photocatalytic Production of Organic Compounds from CO and H
2
O in a Simulated Martian Atmosphere
Authors: Hubbard Jerry S. , Hardy James P. , Horowitz N. H.
Published: May 2006

[
14
C]CO
2
and [
14
C]organic compounds are formed when a mixture of [
14
C]CO and water vapor diluted in [
12
C]CO
2
or N
2
is irradiated with ultraviolet light in the presence of soil or pulverized vycor substratum. The [
14
C]CO
2
is recoverable from the gas phase, the [
14
C]organic products from the substratum. Three organic products have been tentatively identified as formaldehyde, acetaldehyde, and glycolic acid. The relative yields of [
14
C]CO
2
and [
14
C]organics are wavelength- and surface-dependent. Conversion of CO to CO
2
occurs primarily at wavelengths shorter than 2000 Å, apparently involves the photolysis of water, and is inhibited by increasing amounts of vycor substratum. Organic formation occurs over a broad spectral ranger below 3000 Å and increases with increasing amounts of substratum. It is suggested that organic synthesis results from adsorption of CO and H
2
O on surfaces, with excitation of one or both molecules occurring at wavelengths longer than those absorbed by the free gases. This process may occur on Mars and may have been important on the primitive earth.
Isolation of a 5S RNA-Protein Complex from Mammalian Ribosomes
Authors: Blobel Günter
Published: May 2006

5S RNA is removed from the large ribosomal subunit of both rat liver and rabbit reticulocyte ribosomes by treatment with EDTA to remove magnesium ions. The RNA is removed not as a naked molecule, but in association with a single ribosomal protein (molecular weight about 35,000) as a ribonucleoprotein, sedimenting at about 7 S. Conditions for the exclusive removal of the 5S RNA-protein complex have been established.

Both ribosomal subunits undergo distinct changes in their sedimentation rate, concomitant with the loss of their biological activity, when sedimented into sucrose gradients containing high concentrations of monovalent ions and low concentrations of magnesium. Under these conditions the large subunit loses 5S RNA, the 5S RNA-associated protein, and several more proteins.
Lysyl-Protocollagen Hydroxylase Deficiency in Fibroblasts from Siblings with Hydroxylysine-Deficient Collagen
Authors: Krane S. M. , Pinnell S. R. , Erbe R. W.
Published: May 2006

Cell culture studies were performed on members of a family in which two sisters, ages 9 and 12, have a similar disorder characterized clinically by severe scoliosis, joint laxity and recurrent dislocations, hyperextensible skin, and thin scars. The skin collagen from the sisters was markedly deficient in hydroxylysine, but other amino acids were present in normal amounts. Hydroxylysine in collagen from fascia and bone was reduced to a lesser extent. Since the most likely explanation for the hydroxylysine deficiency was a reduction in enzymatic hydroxylation of lysine residues in protocollagen, we measured the activity of lysyl-protocollagen hydroxylase in crude lysates of cultured skin fibroblasts. Enzyme activities in the two affected children were 14 and 10% of controls, whereas the activity was about 60% of normal in the mother, a pattern most consistent with autosomal recessive inheritance. The mutant enzyme demonstrated the same cofactor requirements as that from normal cells. Deficiency of lysyl-protocollagen hydroxylase is the first inborn error of human collagen metabolism to be defined at the biochemical level.
A Manner of Characterizing the Development of Countries
Authors: Herman Robert , Montroll Elliott W.
Published: May 2006

An attempt is made to characterize the socio-economic state and the temporal evolution of countries by the use of labor force distribution data on a multidimensional phase plot so that the development of a country is represented by an evolutionary track of a phase point. The evolutionary tracks of several countries are examined, and the phase points of many countries are compared. Snowflake diagrams, which make easy comparison of the socio-economic character of various countries, have also been developed.
Membrane Site Modified on Induction of the Transformation of Lymphocytes by Periodate
Authors: Novogrodsky Abraham , Katchalski Ephraim
Published: May 2006

Lymphocytes isolated from different sources undergo blastogenesis after mild treatment with periodate. Incubation of mouse spleen lymphocytes with neuraminidase or papain markedly reduces their response to periodate. Transformation induced by concanavalin A of the enzymically treated cells is not impaired. Blastogenesis induced by periodate is decreased when periodate-treated lymphocytes are reacted with borohydride, hydroxylamine, or semicarbazide. Treatment with these compounds does not affect transformation of cells by concanavalin A. It is suggested that different membrane sites are involved in lymphocyte transformation induced by periodate and by concanavalin A. The periodate target site seems to include a glycoprotein complex containing sialic acid that yields, on oxidation, an aldehyde moiety that is essential for transformation.
Regulation of Lymphocyte Responses
In Vitro:
Potentiation and Inhibition of Rat Lymphocyte Responses to Antigen and Mitogens by Cytochalasin B
Authors: Yoshinaga Masaru , Yoshinaga Aiko , Waksman Byron H.
Published: May 2006

Cytochalasin B, at concentration between 0.02 and 0.2 μg/ml, was slightly stimulatory to lymph-node cells from normal rats and greatly potentiated their response to phytohemagglutinin and low concentrations of concanavalin A (mitogens for thymus-derived lymphocytes); it also potentiated the response of thymocytes to phytohemagglutinin. The response of lymphnode cells to lipopolysaccharide endotoxin (a mitogen for thymus-independent lymphocytes) was also enhanced, but only at concentrations in the usual inhibitory range, possibly by inhibition of a “suppressor T-cell” response. Sensitized lymphocytes responding to antigen were not stimulated at all, except at a very high cell density, where inhibition of a “suppressor cell” response was also considered likely. At concentrations of 5-10 μg/ml or higher, cytochalasin B inhibited all responses tested.
Purification of an Ion-Stimulated Adenosine Triphosphatase from Plant Roots: Association with Plasma Membranes
Authors: Hodges T. K. , Leonard R. T. , Bracker C. E. , Keenan T. W.
Published: May 2006

A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg
++
and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (
Avena sativa
L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.

These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots.
An Enhancing Role for DNA Synthesis in Formation of Bacteriophage Lambda Recombinants
Authors: Stahl Franklin W. , McMilin Kenneth D. , Stahl Mary M. , Nozu Yuzo
Published: May 2006

Recombination in some intervals of the map of phage lambda is associated with more DNA synthesis than in other intervals. Blockage of DNA synthesis by high temperature in a host temperature-sensitive for DNA synthesis results in the relative reduction of recombinant frequencies in those regions having the larger amounts of recombination-associated synthesis. Reduction of DNA synthesis at normal temperatures by a combination of the bacterial mutation and a mutation in one of the phage genes required for DNA synthesis has the same consequence. Therefore, DNA synthesis enhances recombinant particle formation more in some map intervals than in others.
Isolation and Characterization of the
S
-Carboxymethyl Derivatives of Crosslinked and Noncrosslinked Human Fibrin
Authors: McDonagh R. P. , McDonagh Jan , Blombäck B.
Published: May 2006

The
S
-carboxymethyl derivative chains of crosslinked and noncrosslinked fibrins were prepared from purified human fibrinogen. For crosslinked fibrin, fibrinogen was clotted with thrombin in the presence of calcium and purified human factor XIII. For noncrosslinked fibrin, ethylenediaminetetraacetate was substituted for factor XIII and calcium. After reduction with dithiothrcitol and alkylation with tritiated iodoacetic acid, the derivative chains were separated on carboxymethyl cellulose in a sodium acetate-pH gradient that contained 8 M urea. Purity of the separated chains was determined by polyacrylamide gel electrophoresis at acid and at neutral pH. The derivative chains of noncrosslinked fibrin were eluted from carboxymethyl cellulose in the order: γ-chain, β-chain, and α-chain. Each of the purified derivative chains was characterized and identified by amino-terminal aminoacid analysis, aminoacid composition, tryptic peptide mapping, and molecular weight estimation by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. In like manner, the derivative components of crosslinked fibrin were eluted from carboxymethyl cellulose in the order: γ-γ-dimer, β-chain, and α-polymer. Application of the same analytical criteria and comparision with the derivatives of noncrosslinked fibrin confirmed the identity of these components. These data provide conclusive evidence that crosslinking of human fibrin involves formation of peptide bonds between two γ-chains to form γ-γ-dimer and between multiple α-chains to form high molecular weight polymers of α-chains.
Replication of Mitochondrial DNA in Mouse L Cells and Their Thymidine Kinase
-
Derivatives: Displacement Replication on a Covalently-Closed Circular Template
Authors: Robberson Donald L. , Clayton David A.
Published: May 2006

Thymidine kinase
-
lines of mouse L cells incorporate thymidine exclusively into mitochondrial DNA. This fact permits assessment of labeled mitochondrial DNA components in ethidium bromide-cesium chloride gradients. Contaminating nuclear DNA is unlabeled and need not be removed. Elimination of the DNase treatment of purified mitochondria reveals that the replicative forms that exhibit displacement replication up to full genome size are covalently-closed circular molecules. Denaturation followed by brief renaturation of these larger replicating molecules produces closed-circular DNA with a deficiency of Watson-Crick turns, appearing as single-strand loops. This result suggests that displacement replication proceeds with nicking and rapid closure of the covalently-closed circular template.
Establishment of Repression by Lambdoid Phage in Catabolite Activator Protein and Adenylate Cyclase Mutants of
Escherichia coli
Authors: Grodzicker Terri , Arditti R. Rita , Eisen Harvey
Published: May 2006

Lambdoid phages form clear plaques and show reduced ability to establish immunity in strains of
Escherichia coli
that lack adenylate cyclase or catabolite activator protein. The absence of the activator protein or cyclic AMP reduces the frequency of lysogenization, but does not prevent steady-state repressor synthesis of a lysogen. Lambda phage mutants able to form turbid plaques on strains that lack catabolite activator protein or adenylate cyclase have been isolated and analyzed.
Expression of Differentiated Functions in Hepatoma Cell Hybrids: Induction of Mouse Albumin Production in Rat Hepatoma-Mouse Fibroblast Hybrids
Authors: Peterson Jerry A. , Weiss Mary C.
Published: May 2006

The synthesis of serum albumin has been studied in hybrids between well-differentiated rat hepatoma cells, which synthesize serum albumin, and mouse fibroblasts (3T3) that do not synthesize albumin. By immunodiffusion techniques with noncrossreacting antisera, the production of both rat and mouse albumin by the hybrids has been examined. Karyologically identified hybrids were produced between 3T3 cells and cells of a 1
s
hepatoma (Fu5) clone, and of a 2
s
hepatoma (2
s
Fu5-5cl.lE) clone. Each of the 3T3 x Fu5 hybrids produces only rat albumin. Among five 3T3 x 2
s
Fu5-5cl.lE hybrid clones isolated, one produces both rat and mouse albumin, two produce only mouse albumin, and two do not produce rat or mouse albumin.
Prebiotic Synthesis of Hydrophobic and Protein Amino Acids
Authors: Ring David , Wolman Yecheskel , Friedmann Nadav , Miller Stanley L.
Published: May 2006

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, α-amino-
n
-butyric acid, α-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, α-hydroxy-γ-aminobutyric acid, and α,γ-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary α-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.
Amino-Acid Composition of Heated Oyster Shells
Authors: Totten David K. , Davidson Franklin D. , Wyckoff Ralph W. G.
Published: May 2006

More than 90% of the protein in the shells of the modern oyster,
Ostrea angelica
, is decomposed when shells are heated at 130° for 1 week. There remains, however, a stable residue that is little changed as heating is continued for 9 weeks. This residue resembles, in both amount and composition, the material previously recovered from fossil oyster shells deposited before the Pliocene era.
A Reassessment of the Course of Evolution of Wheat
Authors: Kimber Gordon , Athwal R. S.
Published: May 2006

Chromosome pairing in hybrids involving
Triticum aestivum
and new accessions of
T. speltoides
, and in an amphiploid of these species, indicates that
T. speltoides
can no longer be considered to be the donor of the B genome of the polyploid wheats. This necessitates a reconsideration of the genome relationships and evolutionary processes that gave rise to cultivated wheats.
Catabolite Repression of Bacterial Bioluminescence: Functional Implications
Authors: Nealson Kenneth H. , Eberhard Anatol , Hastings J. W.
Published: May 2006

The synthesis of the bioluminescent system of the marine luminous bacterium
Photobacterium fischeri
(strain MAV) is subject to both transient and catabolite repression by glucose, and this repression can be reversed by adenosine 3′:5′-cyclic monophosphate. Catabolite repression is a mechanism that characteristically controls the synthesis of inducible enzymes involved in energy metabolism. The fact that luciferase synthesis is subject to this control suggests that whatever its role(s) may be, it cannot be considered a nonfunctional or vestigial enzyme system as previously hypothesized, and may actually have some more direct role in metabolic processes.
Low Activity of β-Galactosidase in Frameshift Mutants of
Escherichia coli
Authors: Atkins John F. , Elseviers Dirk , Gorini Luigi
Published: May 2006

16
lac
frameshift mutants induced by an acridine derivative, ICR-191D, in
E. coli
are leaky for β-galactosidase activity. Activities of all mutants differ from each other and from the wild type in their stability to thermal denaturation. The leakiness is under ribosomal control, since it is strongly reduced by
strA
restrictive mutations and is restored by
ram
mutations that reverse restriction. Addition of streptomycin during growth has an effect similar to the presence of the
ram
mutation. These ribosomal alterations do not modify the thermal stability of the enzyme.

It is suggested that the leakiness is due to an infrequent 2- or 4-base reading close to the frameshift mutation site. The possibility that not only the ribosome, but also the reading context in the messenger, plays a role in securing code fidelity is discussed.
The Chemistry of Olfactory Reception: Stimulus-Specific Protection from Sulfhydryl Reagent Inhibition
Authors: Getchell Marilyn Levisohn , Gesteland Robert C.
Published: May 2006

The group-specific protein reagent,
N
-ethylmaleimide, irreversibly blocks the electrical response of the olfactory receptor organ of the frog to odorous stimuli. If the odorous substance, ethyl
n
-butyrate, in concentrations high enough to saturate the receptor system, is present in the nasal cavity before and during a brief exposure to
N
-ethylmaleimide, the nose, after a wash and a recovery period, responds in nearly normal fashion to vapors of ethyl
n
-butyrate. Responses to other odorous substances, except those closely related to ethyl
n
-butyrate, are abolished. We propose that we can use this protection technique to identify the properties of the various receptor sites in the nose, and possibly to characterize the receptor substances.
Surface Properties of Membrane Systems: Apoprotein of the Folch-Lees Proteolipid from Beef-Brain Myelin
Authors: Colacicco G. , Hendrickson H. , Joffe S.
Published: May 2006

Structural proteins in biological membranes are bimodal and ideally possess a unique surface activity that should be amenable to study by monolayer techniques. Proteins so studied, however, display, of necessity, a surface activity that reflects the laboratory history of the protein. The Folch-Lees proteolipid apoprotein was isolated from calf-brain myelin in both an organic solvent (CHCl
3
-CH
3
OH-CH
3
COOH; 50:50:1) and water. The apoprotein did not spread as a film from water, but did spread readily from the organic solvent into films that had high saturation pressures. The partitioning of the apoprotein from organic solvent to water was found to be reversible, as was the gain and loss of surface activity. Infrared spectroscopy demonstrated that the preponderant structure in films of the apoprotein was not that of extended polypeptide chains. The results suggested that the preferred structures at the interface are bimodal coils of alpha helix. This structure can sustain the high film pressures observed, whereas beta keratin structures would build films with high surface viscosity and very low surface pressure.
Phenylalanyl-tRNA Synthetase and Isoleucyl-tRNA
Phe
: A Possible Verification Mechanism for Aminoacyl-tRNA
Authors: Yarus Michael
Published: May 2006

The synthesis of isoleucyl-tRNA
Phe
(
Escherichia coli
) proceeds at an appreciable rate under normal
in vitro
conditions in the presence of isoleucyl-tRNA synthetase (EC 6.1.1.5) from
E. coli
. The misacylated product is shown here to be hydrolyzed by highly purified phenylalanyl-tRNA synthetase from
E. coli
, with release of isoleucine and active tRNA
Phe
. Thus, phenylalanyl-tRNA synthetase possesses a previously unrecognized activity, which deacylates a mistakenly acylated tRNA
Phe
; the enzyme is inactive toward correctly matched aminoacyl tRNAs. Such a mechanism could serve to verify aminoacyl-tRNAs, deacylating those that are misacylated. Thus, a common generalization needs to be modified: an amino acid is not necessarily committed to a given (incorrect) anticodon when it is incorporated into aminoacyl-tRNA. It may be possible to correct it thereafter.
Reactions Involved in Bioluminescence Systems of Limpet (
Latia neritoides
) and Luminous Bacteria
Authors: Shimomura Osamu , Johnson Frank H. , Kohama Yasuhiro
Published: May 2006

Luminescence in
Latia
involves a specific flavoprotein enzyme (“luciferase”), which has a tightly bound flavin group constituting the light-emitter. The overall reaction includes oxidation of a specific substrate (“luciferin,” an enol formate derivative of an aliphatic aldehyde), by 2 O
2
molecules, in the presence of a “purple protein” cofactor, yielding a ketone, HCOOH, CO
2
, and light. In
Achromobacter
, a required aliphatic aldehyde, which is functionally equivalent to
Latia
luciferin, is oxidized to an acid containing the same hydrocarbon chain as the aldehyde; this reaction proceeds in the presence of bacterial luciferase and reduced flavin mononucleotide with a quantum yield of 0.17 + 0.1 photons per aldehyde molecule that is independent of aldehyde chain length from 9 to at least 14 carbons.
Coboglobins: Heterotropic Linkage and the Existence of a Quaternary Structure Change Upon Oxygenation of Cobaltohemoglobin
Authors: Hsu G. C. , Spilburg C. A. , Bull C. , Hoffman B. M.
Published: May 2006

Cobaltohemoglobin prepared from horse hemoglobin retains the full heterotropic linkage properties of the normal iron hemoglobin, including both the Bohr and phosphate effects. From this result, and the known connection between heterotropic linkage properties and hemoglobin conformational change, it is concluded that cobaltohemoglobin undergoes a quaternary structure transition upon oxygenation. Thus, the stereochemical changes that occur upon oxygen binding to cobalt, as well as to iron, must be compatible with the mechanism triggering such a transition.
Conformational Studies of Various Hemoglobins by Natural-Abundance
13
C NMR Spectroscopy
Authors: Moon R. B. , Richards J. H.
Published: May 2006

Studies of variously liganded hemoglobins (both from human and rabbit) by natural-abundance
13
C NMR spectroscopy have revealed apparent conformational differences that have been interpreted on the basis of two quaternary structures for the α
2
β
2
tetramer, and variable tertiary structures for the individual α and β subunits. In solution, rabbit hemoglobins appear to have somewhat more flexibility than human hemoglobins.
Intracellular Distribution of Enzymes of the Cytidine Diphosphate Choline Pathway in Castor Bean Endosperm
Authors: Lord J. M. , Kagawa T. , Beevers Harry
Published: May 2006

The occurrence and subcellular distribution of enzymes of the cytidine diphosphate choline pathway of lecithin synthesis have been examined. Choline kinase (EC 2.7.1.32) was completely soluble, while phosphorylcholine-cytidyl transferase (EC 2.7.7.15) and phosphorylcholine-glyceride transferase (EC 2.7.8.2) were associated with particulate fractions. Although components sedimenting at 10,000 to 100,000 ×
g
contained both enzymes, phosphorylcholine-cytidyl transferase and particularly phosphorylcholine-glyceride transferase were present in the 10,000 ×
g
pellet, which contained the major organelles, mitochondria, and glyoxysomes. When the crude homogenate was centrifuged on a sucrose density gradient, four major bands of particulate protein were recovered. A band at density 1.24 g/cm
3
contained the glyoxysomes and was devoid of phosphorylcholine-cytidyl transferase and phosphorylcholine-glyceride transferase activity. Enzyme activity was barely detectable in the mitochondria, at density 1.18 g/cm
2
. Phosphorylcholine-glyceride transferase was found almost exclusively in a sharp band at density 1.12 g/cm
3
, and phosphorylcholinecytidyl transferase was found in the uppermost band at density 1.08 g/cm
3
. Thus, for the synthesis of lecithin in their membranes, the glyoxysomes and mitochondria depend on enzymes elsewhere in the cell; the final two steps in lecithin formation occur, apparently exclusively, in separate particulate cell components.
Reducible Crosslinks in Hydroxylysine-Deficient Collagens of a Heritable Disorder of Connective Tissue
Authors: Eyre David R. , Glimcher Melvin J.
Published: May 2006

Reducible compounds that participate in crosslinking were analyzed in hydroxylysine-deficient collagens of patients with a heritable disorder of connective tissue. After treatment with [
3
H]sodium borohydride, new compounds, as well as a totally different pattern of tritiated compounds, were found in hydroxylysine-deficient collagen from skin as compared with age-matched controls. The amount of desmosines detected indicated that more elastin was present in abnormal skin than in control skin.

Bone collagen, which was not as deficient in hydroxylysine as skin collagen, had the same compounds as normal bone collagen, but their relative proportions were altered, consistent with a deficiency of hydroxylysine, a precursor of the crosslinks. Although the content of hydroxylysine in collagen of cartilage is essentially normal in these patients, analysis after reduction revealed a different pattern of reduced compounds from that of normal cartilage. It is speculated that Type II collagen, the major collagen component in cartilage, contains a normal amount of hydroxylysine, while Type I collagen, which is the major source of the crosslinks, is hydroxylysine-deficient. This distribution would explain the findings of an abnormal profile of reducible compounds despite an almost normal total hydroxylysine content.

The finding that the deficiency of hydroxylysine in the collagen of these patients is accompanied by changes in number, chemical nature, and, probably, distribution of crosslinkages, and the previously reported alterations in the solubility characteristics, suggest that at least some skeletal and connective tissue abnormalities are directly related to underlying molecular pathology.
Preparation and Properties of Phospholipid Bilayers Containing Rhodopsin
Authors: Hong Keelung , Hubbell Wayne L.
Published: May 2006

Purified rhodopsin has been prepared containing less than 1.1 mol of phosphate per mol of protein. The purified rhodopsin has been incorporated into phosphatidylcholine bilayers, and the molecular interactions within the bilayers were investigated by the use of spin-labeled phosphatidylcholines. Rhodopsin appears to inhibit segmental motions of the hydrocarbon chains, an effect similar to that of cholesterol on phospholipid bilayers.
Qualitative Differences in the
N
-Acetyl-D-galactosaminyltransferases Produced by Human
A
1
and
A
2
Genes
Authors: Schachter H. , Michaels M. A. , Tilley Christine A. , Crookston Marie C. , Crookston J. H.
Published: May 2006

This study describes the kinetic properties of
N
-acetyl-D-galactosaminyltransferase in serum from subjects with blood groups A
1
and A
2
. When the
A
1
and
A
2
enzymes were compared, with lacto-
N
-fucopentaose I and 2′-fucosyllactose as acceptors, the enzymes differed in their cation requirements, pH optima, and

K
m

values. The two acceptors competed for the same transferase. Mixing experiments showed that the lower activity of the
A
2
enzyme could not be attributed to a modifier or inhibitor in serum. It was concluded that the
A
1
and
A
2
enzymes differ qualitatively.
Modification of RNA Polymerase after T3 Phage Infection of
Escherichia coli
B
Authors: Dharmgrongartama B. , Mahadik S. P. , Srinivasan P. R.
Published: May 2006

E. coli
B cells infected with T3 phage contain a modified host RNA polymerase in addition to the normal RNA polymerase found in uninfected cells. The modified RNA polymerase behaves differently in its elution properties from the normal enzyme on DEAE-cellulose, phosphocellulose, and DNA-cellulose column chromatography. The modified enzyme also differs from the normal polymerase in some of its enzymatic parameters. The specific activity of the modified RNA polymerase is markedly lower (i.e., ¼) than that of the normal enzyme. The decrease in activity is probably due to an alteration in the β′ subunit of the polymerase. A similar modification is also observed in nonpermissive cells infected with a gene-l amber mutant incapable of producing active T3 specific polymerase. An analogous modification in host RNA polymerase does not seem to occur in
E. coli
cells infected with T7 phage.
Mechanisms of Lysosomal Enzyme Release from Human Leukocytes: Microtubule Assembly and Membrane Fusion Induced by a Component of Complement
Authors: Goldstein Ira , Hoffstein Sylvia , Gallin John , Weissmann Gerald
Published: May 2006

A low-molecular-weight component of complement, similar to or identical with human C5a, interacts with human polymorphonuclear leukocytes treated with cytochalasin B and provokes extracellular release of lysosomal enzymes from these cells. Enzyme release occurs in the absence of particles and is selective in that it is not accompained by release of cytoplasmic enzymes. Cell viability is not altered. Pharmacologic agents that regulate secretion of other inflammatory mediators influenced complement-dependent enzyme release: cAMP and theophylline, prostaglandin E
1
and colchicine
inhibited
, whereas cGMP
enhanced
release of enzymes. Ultra-structural histochemistry of cells exposed to this component of complement revealed degranulation, fusion of lysosomal with plasma membranes, and transient assembly of microtubules associated with the release of endogenous myeloperoxidase. Our findings suggest that these intracellular events are common to two important responses of polymorphonuclear leukocytes in inflammation and tissue injury: (
a
) release of lysosomal hydrolases and (
b
) chemotaxis.
Analysis of Gene Diversity in Subdivided Populations
Authors: Nei Masatoshi
Published: May 2006

A method is presented by which the gene diversity (heterozygosity) of a subdivided population can be analyzed into its components, i.e., the gene diversities within and between subpopulations. This method is applicable to any population without regard to the number of alleles per locus, the pattern of evolutionary forces such as mutation, selection, and migration, and the reproductive method of the organism used. Measures of the absolute and relative magnitudes of gene differentiation among subpopulations are also proposed.
Alteration of the Relative Stability of dA·dT and dG·dC Base Pairs in DNA
Authors: Melchior William B. , Von Hippel Peter H.
Published: May 2006

Several small alkylammonium ions can eliminate, or even reverse, the usual dependence of the DNA transition temperature on base composition. For example, in 3 M tetramethylammonium chloride, or 2.4 M tetraethylammonium chloride, DNAs of different base compositions all melt at a common temperature, and with a greatly decreased breadth of transition reflecting only the sequence-independent components of melting cooperativity. At still higher concentrations of such additives, dG·dC-rich DNAs melt at lower temperatures than dA·dT-rich molecules. Circular dichroism spectra show that these additives alter the structure of the DNA double helix very little at room temperature. This differential (base-specific) effect on helix stability is investigated with several small additives related to the tetraalkylammonium ions. Additives larger than tetraethylammonium ion have little differential effect on helix stability. Preferential binding of ions to dA·dT base pairs, requiring fit into a “groove” of DNA, is consistent with these data and with equilibrium binding studies. These differential effects can be distinguished from general destabilizing effects, which are independent of specific features of macromolecular conformation or chemistry. Possible experimental uses of this ability to alter the base-composition-dependent components of the stability of the DNA helix are discussed, as well as the insight this phenomenon provides into the molecular basis for the differential stability of dA·dT and dG·dC base pairs.
Microtubule Assembly in the Absence of Added Nucleotides
Authors: Shelanski Michael L. , Gaskin Felicia , Cantor Charles R.
Published: May 2006

Microtubule assembly is enhanced by the addition of 1 M sucrose or 4 M glycerol to the reassembly mixture. Tubulin can be purified from guinea pig brain readily and in good yield by two cycles of assembly in glycerol-containing solutions. The tubules assembled in glycerol and sucrose are more stable than tubules formed in the absence of these compounds. Assembly occurs in glycerol or sucrose in the absence of ATP or GTP, but is greatly accelarated by their presence.
Pleiotypic Control by Adenosine 3′:5′-Cyclic Monophosphate: A Model for Growth Control in Animal Cells
Authors: Kram Raphaël , Mamont Pierre , Tomkins Gordon M.
Published: May 2006

The effects of serum deprivation on several general cellular biochemical processes (“pleiotypic response”) related to the growth of normal fibroblasts can be mimicked by treatment of these cells with prostaglandin E
1
in the presence of serum.
N
6
,
O
2
′-Dibutyryl adenosine 3′:5′-cyclic monophosphate and theophylline inhibit the membrane transport processes without much effect on other pleiotypic reactions such as overall protein and RNA synthesis and protein degradation. The amount of intracellular cyclic AMP increases during serum starvation and returns to the initial concentration in unstarved cells when growth is initiated again upon addition of serum. Fibroblasts transformed by simian virus 40 have a lower cyclic AMP content than their untransformed parents. Serum deprivation neither increases cyclic AMP content nor significantly affects the pleiotypic reactions in transformed cells. Cycloheximide causes a decrease in cyclic AMP content of normal fibroblasts coincidentally with the ability of this inhibitor to stimulate uridine transport and slow protein degradation in cells deprived of serum.
Identification of a Large Polypeptide Precursor of Avian Oncornavirus Proteins
Authors: Vogt Volker M. , Eisenman Robert
Published: May 2006

Antibody to partially disrupted avian myeloblastosis virus was used to selectively precipitate newly synthesized intracellular viral polypeptides from extracts of infected chicken cells. When analyzed by sodium dodecyl sulfate-gel electrophoresis, immune precipitates from extracts of cells pulse-labeled for 10 min with [
35
S]methionine contain none of the major virion polypeptides. Instead they show prominent viral specific polypeptides of molecular weight 76,000 and 12,000, as well as minor quantities of other labeled polypeptides. From pulse-chase kinetics and two-dimensional tryptic finger-prints it appears that the large polypeptide is a precursor of at least the two major virion proteins of molecular weights 24,000 and 11,000, while the smaller is a precursor of the 11,000-dalton virion protein.
Hydrogen Evolution by a Chloroplast-Ferredoxin-Hydrogenase System
Authors: Benemann John R. , Berenson Jeffrey A. , Kaplan Nathan O. , Kamen Martin D.
Published: May 2006

Spinach chloroplast preparations were mixed with
Clostridium kluyveri
hydrogenase and ferredoxin. Hydrogen evolution could be measured in the light in the absence of any added electron donors. Inhibition of the water-splitting reaction or of photosystem II reduced the amount of H
2
evolved more than 95%, indicating that H
2
O was the electron donor in this reaction. The rates of H
2
evolution observed were up to 20% of those measured in the presence of an oxygen-consuming reaction or of photosystem I electron donors. These findings indicate that hydrogen evolution from water and sunlight by photosynthetic processes could be a method for solar energy conversion.