bluuebunny/crossref_metadata_2025 huggingface dataset:
High rates of nitrogen fixation during an in‐situ phosphate release experiment in the Eastern Mediterranean Sea
Authors: Rees Andrew P. , Law Cliff S. , Woodward E. Malcolm S.
Published: May 2006

Nitrogen fixation and δ15N were measured within a warm‐core eddy during an in‐situ phosphate experiment (CYCLOPS) in the Eastern Mediterranean, with experimental procedures performed on unconcentrated, bulk water. Mean rates of 129 nmol‐N L−1d−1 were measured at control stations in the absence of phosphate (<2 nmolL−1), inferring the bioavailability of DOP to diazotrophs. In P‐enriched waters, rates increased by 48% to 197 nmol‐N L−1d−1 five days after addition. δ15N of particulate material was homogenous throughout the upper mixed layer, but changed with time at both amended and control stations from +3.8‰ on day 1, to −0.6‰ on day 4–5 before returning to +3.1‰ after 9 days. This trend matched the observed response in other components of the biota and biogeochemistry in the P‐enriched patch. In‐vitro addition experiments indicated that diazotrophy was not limited by Fe availability.
Detection of an unusually large hydrothermal event plume above the slow‐spreading Carlsberg Ridge: NW Indian Ocean
Authors: Murton Bramley J. , Baker Edward T. , Sands Carla M. , German Christopher R.
Published: May 2006

About 90% of Earth's volcanism occurs along the global mid‐ocean ridge system. Here, sporadic volcanic and tectonic activity is thought to cause cataclysmic release of hydrothermal fluids, forming event plumes. Each plume often contains as much hydrothermal effluent and heat as chronic hydrothermal venting from a typical vent site discharges during a year. To date, only a few event plumes have been detected, and only above intermediate‐rate spreading ridges in the Pacific. Here, we report the first evidence for an unusually large event plume that originated from the slow‐spreading (3 cm/yr full‐rate) Carlsberg Ridge in the NW Indian Ocean. At 70 km long, up to 4540 km3 in volume and with up to 24 × 1016 J of excess heat, this event plume was substantially larger than previous ones and demonstrates that dispersion of hydrothermal heat and biological products from slow spreading ridges may be more significant and effective than hitherto imagined.
Protein Kinase C Inhibition Prevents Upregulation of Vascular ETB and 5-HT1B Receptors and Reverses Cerebral Blood Flow Reduction after Subarachnoid Haemorrhage in Rats
Authors: Beg Saema S , Hansen-Schwartz Jacob A , Vikman Petter J , Xu Cang-Bao , Edvinsson Lars I
Published: May 2006

The pathogenesis of cerebral ischaemia after subarachnoid haemorrhage (SAH) still remains elusive. The purpose of the present study was to examine whether specific protein kinas C (PKC) inhibition in rats could alter the transcriptional SAH induced Endothelin (ET) type B and 5-hydroxytryptamine type 1B (5-HT1B) receptor upregulation and prevent the associated cerebral blood flow (CBF) reduction. The PKC inhibitor RO-31-7549 or vehicle was injected intracisternally after the induced SAH in rats ( n = 3 to 10 in each groups for each method). The involvement of the PKC isoforms was investigated with Western blot; only PKCδ and PKCα subtypes were increased after SAH RO-31-7549 treatment abolished this. At 2 days after the SAH basilar and middle cerebral arteries were harvested and the contractile response to endothelin-1 (ET-1; ETA and ETB receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) were investigated with a myograph. The contractile responses to ET-1 and 5-CT were increased ( P < 0.05) after SAH compared with sham operated rats. In parallel, the ETB and 5-HT1B receptor mRNA and protein expression were significantly elevated after SAH, as analysed by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Administration of RO-31-7549 prevented the upregulated contraction elicited by application of ET-1 and 5-CT in cerebral arteries and kept the ETB and 5-HT1B receptor mRNA and protein levels at pre-SAH levels. Regional and global CBF evaluated by an autoradiographic technique were reduced by 60%±4% after SAH ( P < 0.05) and prevented by treatment with rO-31-7549. Our study suggests that PKC plays an important role in the pathogenesis of cerebral ischaemia after SAH.
Oxygen sensing junctions based on yttria stabilized zirconia with platinum nanoparticles
Authors: Dimitrov Dimitre Tz. , Anastasova Salzitsa Y. , Dushkin Ceco D.
Published: May 2006

We invent new types of ceramic sensor junctions for detection of oxygen. Their electrodes comprise thin films of yttria stabilized zirconia (YSZ) obtained by spray pyrolysis: pure YSZ and YSZ reinforced with platinum nanoparticles. The potential difference of the sensors is measured as a function of temperature and described by empirical equation. In dynamic conditions this difference exhibits a well pronounced cyclic behavior sensitive to the oxygen content. The potential difference logarithmically depends on the oxygen concentration at a fixed temperature, which is proven both experimentally and theoretically. This difference has a minimum at particular concentration of platinum in the ceramics.
Power-law E(J) characteristic converted from field-amplitude and frequency dependent ac susceptibility in superconductors
Authors: Chen D.-X. , Pardo E.
Published: May 2006

The power-law E(J) characteristic of a superconductor may be determined by ac susceptibility (χ=χ′−jχ″) measurements from the field amplitude at which χ″ takes maximum, Hm(χm″), and frequency f. The relation between E vs J and Hm(χm″) vs f obtained from direct calculations of χ for a long cylinder and a thin disk with a power-law E(J) provides a firm base for the ac susceptibility technique of Jc determination of advanced high-temperature superconductors.
Ground-state lasing of stacked InAs∕GaAs quantum dots with GaP strain-compensation layers grown by metal organic chemical vapor deposition
Authors: Tatebayashi J. , Nuntawong N. , Xin Y. C. , Wong P. S. , Huang S. H. , Hains C. P. , Lester L. F. , Huffaker D. L.
Published: May 2006

We report the device characteristics of stacked InAs∕GaAs quantum dots (QDs) with GaP strain-compensation (SC) layers grown by metal organic chemical vapor deposition. By inserting GaP SC layers within the stacked structures, decrease in the density of QDs by stacking QDs can be suppressed due to reduction of overall compressive strain within the stacked QDs. We demonstrate ground-state lasing at 1.265μm of six layers of InAs∕GaAs QDs with GaP SC layers. The threshold current density is as low as 108A∕cm2. We also assess the internal loss and maximum modal gain of fabricated QD lasers by using a segmented contact method. The internal loss is as low as 5cm−1, and the maximum modal gain of the ground state of the stacked QDs is approximately 10cm−1.
High-temperature threshold characteristics of a symmetrically graded InAlAs∕InxGa1−xAs∕GaAs metamorphic high electron mobility transistor
Authors: Lee C. S. , Chen Y. J. , Hsu W. C. , Su K. H. , Huang J. C. , Huang D. H. , Wu C. L.
Published: May 2006

High-temperature threshold characteristics of a symmetrically graded δ-doped InAlAs∕InxGa1−xAs∕GaAs (x=0.5→0.65→0.5) metamorphic high electron mobility transistor (MHEMT) have been investigated. The thermal threshold coefficients, defined as ∂Vth∕∂T, are superiorly low at 0.9mV∕K from 300to420K and at −0.75mV∕K from 420to500K. An interesting polarity change of the thermal threshold coefficient was observed around 420K due to the variation of thermal modulation effects. The present MHEMT device, with stabilized thermal threshold variations and superior high-temperature linearity characteristics, is promising for high-temperature circuit applications.
Evaluation of MM5 model resolution when applied to prediction of National Fire Danger Rating indexes
Authors: Hoadley Jeanne L. , Rorig Miriam L. , Bradshaw Larry , Ferguson Sue A. , Westrick Kenneth J. , Goodrick Scott L. , Werth Paul
Published: May 2006

Weather predictions from the MM5 mesoscale model were used to compute gridded predictions of National Fire Danger Rating System (NFDRS) indexes. The model output was applied to a case study of the 2000 fire season in Northern Idaho and Western Montana to simulate an extreme event. To determine the preferred resolution for automating NFDRS predictions, model performance was evaluated at 36, 12, and 4 km. For those indexes evaluated, the best results were consistently obtained for the 4-km domain, whereas the 36-km domain had the largest mean absolute errors. Although model predictions of fire danger indexes are consistently lower than observed, analysis of time series results indicates that the model does well in capturing trends and extreme changes in NFDRS indexes.
Effect of heat on seed germination of Pinus sylvestris and Pinus nigra ssp. pallasiana
Authors: Turna Ibrahim , Bilgili Ertugrul
Published: May 2006

The present note presents and explains the results of a study dealing with the germination of seeds subjected to heat. Seeds of Scots pine (Pinus sylvestris L.) and Anatolian black pine (Pinus nigra ssp. pallasiana) were exposed to a range of temperatures (70, 90, 110, 130, and 150°C) for different exposure times (1 and 5 min). Germination rates were similar for all treatments and control at 1 min exposure for Anatolian black pine seeds, and almost no germination took place for all treatments at 5 min exposure. Similar results were obtained for Scots pine seeds, with the exception of a sharp decrease in the number of seeds germinated above 110°C. The effect of increasing the exposure time to 5 min was immediate, and no germination took place above 90°C. Results obtained indicate that seeds of the two species do not necessarily need fire for successful regeneration, but fires may have a positive effect on the germination by removing crown cover, thereby providing more light for the seeds deposited to the ground.
Estimating site occupancy and detectability of an endangered New Zealand lizard, the Otago skink (Oligosoma otagense)
Authors: Roughton Catherine M. , Seddon Philip J.
Published: May 2006

There is a need to develop appropriate monitoring methods for cryptic reptile species, such as the endangered New Zealand endemic Otago skink (Oligosoma otagense), that take into account incomplete detectability. A recently developed analytical technique was applied to presence–absence data for Otago skinks to derive robust estimates of both detection probability and site occupancy. The estimated detection probability for Otago skinks was 0.4 (s.e. 0.052), and the estimate of the proportion of the study area occupied by Otago skinks was 0.71 (s.e. 0.11). The data derived from presence–absence surveys in consistently sunny weather, with a standardised scanning and searching technique, provided a good basis for robust estimates of detection probability and of the percentage of area occupied by skinks. This survey technique could be applied to other similarly cryptic reptile species to derive rigorous estimates of site occupancy in order to track changes over time or in response to management interventions. It will be particularly appropriate where precise estimation of absolute abundance is not warranted, or where a simple index of relative abundance may be invalid due to failure of the implicit assumption of constant detectability.
RANDOM EVOLUTIONS, MARKOV CHAINS, AND SYSTEMS OF PARTIAL DIFFERENTIAL EQUATIONS
Authors: Griego R. J. , Hersh R.
Published: May 2006

Several authors have considered Markov processes defined by the motion of a particle on a fixed line with a random velocity
1, 6, 8, 10
or a random diffusivity.
5, 12
A “random evolution” is a natural but apparently new generalization of this notion. In this note we hope to show that this concept leads to simple and powerful applications of probabilistic tools to initial-value problems of both parabolic and hyperbolic type. We obtain existence theorems, representation theorems, and asymptotic formulas, both old and new.
THE FACILE ISOLATION OF A STRUCTURAL PHOSPHOLIPOPROTEIN FROM
Hydrogenomonas facilis
AND
Neurospora crassa
Authors: Kuehn Glenn D. , McFadden Bruce A. , Johanson Roy A. , Hill John M. , Shumway Lewis K.
Published: May 2006

The paper describes a new and gentle procedure for isolating “structural” phospholipoproteins from organisms and the first such isolation from a procaryotic microbe,
Hydrogenomonas facilis
.

The amino acid composition of its protein moiety resembles that of “structural protein” from other sources. Although disc gel electrophoresis has shown the protein to be heterogeneous, this is attributed to aggregation.
EVIDENCE FOR ONE FUNCTIONAL PHENYLALANYL TRNA BINDING SITE ON THE 30
S
RIBOSOMAL SUBUNIT
Authors: Igarashi Kazuei , Kaji Akira
Published: May 2006

NH
2
terminal analysis of polyphenylalanine formed from 30S subunit-bound
14
C-phenylalanyl-tRNA suggests that there is only one site in a 30S subunit for specific binding of phenylalanyl-tRNA. Assuming that no movement of the bound phenylalanyl-tRNA takes place during association of 30S subunits with 50S ribosomal subunits, the binding site of the 30S ribosomal subunit corresponds to site 2 (—NH
2
side with respect to the growing polypeptide chain) of the two binding sites of 70S ribosomes.
STUDIES ON MEMORY: EVIDENCE FOR A WIDESPREAD MEMORY TRACE IN THE NEOCORTEX AFTER THE SUPPRESSION OF RECENT MEMORY OF PUROMYCIN
Authors: Flexner Josefa B. , Flexner Louis B.
Published: May 2006

Intracerebral injections of puromycin in mice have provided evidence that the hippocampal area of the brain contains the memory trace of recently learned maze behavior and that, with time, the trace is also found in the neocortex. The present experiments were planned to determine whether this enlargement of locus would develop after the blockage of recent memory in the hippocampus by puromycin, i.e., whether the neocortical locus is established if hippocampal memory is suppressed. The experiments depend upon our earlier finding that the memory blockage caused by puromycin can be removed by small intracerebral injections of saline. Control experiments showed that saline injected into the frontal cortex three days after training did not release the puromycin blockage of memory in the hippocampal area. Injections of saline into the frontal cortex 6 and 11 days after training did, however, release memory in mice whose recent memory had been suppressed by puromycin; we interpret this result to mean that the memory trace appears widely in the cortex despite the suppression of recent memory in the hippocampus. The theoretical implications of this finding are briefly discussed.
DIFFERENCES IN THE TRANSFER RNA'S OF NORMAL LIVER AND NOVIKOFF HEPATOMA
Authors: Baliga B. S. , Borek E. , Weinstein I. B. , Srinivasan P. R.
Published: May 2006

—A comparison of the elution profiles of 18 aminoacyl-tRNA's from Novikoff hepatoma with those from normal liver on a methylated albuminkieselguhr column revealed the occurrence of new species of tRNA for histidine, tyrosine, and asparagine in the hepatoma. In addition, the hepatoma tRNA's for arginine, isoleucine, lysine, methionine, serine, alanine, and tryptophan eluted at a higher salt concentration than the corresponding tRNA's of normal liver. The remaining eight amino acids did not show any significant differences in the elution profiles.
PRIMARY STRUCTURE OF WHEAT GERM PHENYLALANINE TRANSFER RNA
Authors: Dudock Bernard S. , Katz Gerson , Taylor Ellen K. , Holley Robert W.
Published: May 2006

The complete nucleotide sequence of wheat germ phenylalanine transfer RNA (tRNA
Phe
) is presented. This RNA, which is an acceptable substrate for yeast phenylalanine tRNA synthetase, has a structure very similar to that of yeast tRNA
Phe
. Only 16 of the 76 nucleotides are different, and all but two of the nucleotide changes are located in regions that are doublestranded in the cloverleaf model. The two changes in single-stranded regions involve minor modifications of the same nucleotide. The dihydrouridine loop and its supporting stem are completely free of nucleotide changes.
TRANSLATION OPERATORS ON THE HALF-LINE
Authors: Coburn L. A. , Douglas R. G.
Published: May 2006

The self-adjoint algebra of operators generated by the semigroup of translation operators acting on the Hilbert space of functions supported on the half-line is studied. A real-valued index is introduced and is used to determine the spectrum of the Wiener-Hopf integral operators with distribution kernel having an almost periodic Fourier transform. Further, the algebra is shown to contain no nonzero compact operators, and the quotient of the algebra by its commutator ideal is shown to be isometrically isomorphic to the Banach algebra of almost periodic functions on the line.
THE L-ARABINOSE OPERON IN
Escherichia coli
B/r: A GENETIC DEMONSTRATION OF TWO FUNCTIONAL STATES OF THE PRODUCT OF A REGULATOR GENE
Authors: Englesberg Ellis , Squires Craig , Meronk Frank
Published: May 2006

The product of the regulator gene
araC
in the L-arabinose gene complex exists in two functional states: P1, the repressor, and P2, the activator, presumably in equilibrium with each other, and with P1 and P2 attached to their respective controlling sites,
araO
, the operator, and
araI
, the initiator. The controlling sites are linked in the following order with respect to genes
araB
and
araC: BIOC
. Two
C
gene deletions (Δ719 and Δ766) serve to define the newly described
araO
site, and to place it adjacent to the left end of the
C
gene. We have suggested that deletion 719 deletes, in addition to the
C
gene, part or all of the
araO
site. Deletion 766 leaves the
araO
site intact. Complementation analysis employing stable merodiploids indicates that the repressor-operator site function is epistatic over the activator-initiator site function. It is necessary both for activator (P2) to be present and for repressor (P1) to be absent at their respective controlling sites (
araI
and
araO
) for full expression of the L-arabinose operon.
GIANT NUCLEOPLASMIC RNA IN THE SWITCH-ON OF COMPENSATORY RENAL GROWTH
Authors: Willems Margherita , Musilova Hana A. , Malt Ronald A.
Published: May 2006

Heterogeneous RNA (HnRNA) (
ca.
10
S
-70
S
) labeled for ten minutes with
3
H-uridine was identified by polyacrylamide-gel electrophoresis in the nucleoplasm of kidney cells. In the region >28
S
several discretely migrating species were present. Ten minutes after the removal of one kidney, labeled HnRNA >28
S
(“giant” HnRNA) in the remaining kidney began to decrease, and by 60 minutes it had fallen drastically. The presence of labeled giant HnRNA during a pulse label after uninephrectomy and its disappearance after longer labeling suggest that the decrease is a consequence of faster processing. Accelerated processing of giant HnRNA is antecedent to the increased synthesis of renal cytoplasmic RNA that follows uninephrectomy.
REGULATORY EFFECTS OF SUBSTRATES ON A PHOSPHOTRANSFERASE FROM
Aerobacter aerogenes
AND THE MODIFICATION OF ITS ACTIVITY BY PARTIAL PROTEOLYSIS
Authors: Schaefler S. , Schenkein I.
Published: May 2006

An enzyme isolated from
Aerobacter aerogenes
acts both as phosphomonoesterase and phosphotransferase with glucose, glucosides, glucosamine, and N-acetyl glucosamine as acceptors. When glucose-6-phosphate is the phosphate donor, these acceptors appear to act as activators of the enzyme, while with
p
-nitrophenyl phosphate, α-glycerophosphate, fructose-1,6-diphosphate, and several other phosphate esters as donors, the same acceptors act as noncompetitive inhibitors. With
p
-nitrophenyl phosphate as the phosphate donor, no inhibition is observed when glucose is replaced as acceptor by 2-deoxy glucose. The inhibition by glucose and other acceptors is eliminated at low pH or by increasing the temperature of reaction. Partial proteolysis of the enzyme by chymotrypsin produces a modified enzyme (gl-phosphotransferase-Ch) that shows altered relative velocities for the hydrolysis of several substrates as well as altered regulatory effects by acceptors.
STRAND-SPECIFIC TRANSFER OF DONOR DNA DURING CONJUGATION IN
E. coli
Authors: Ihler Garret , Rupp W. Dean
Published: May 2006

After conjugation of
E. coli
, only the preformed donor DNA strand with a leading 5′ end can be recovered from the recipient. DNA that was transferred to recipients from radioactive-labeled donor strains lysogenic for λ bacteriophage was recovered as radioactive material in mature phage particles. The radioactivity was recovered in strand
l
when gene transfer was in the order gal-λ-bio, and in strand
r
when the order of transfer was bio-λ-gal. The assignment of the 5′ end as the origin of the transferred strand follows directly from the known orientation of prophage λ in the chromosome.
REMARKS ON SEQUENTIAL POINT ESTIMATION
Authors: Starr Norman , Woodroofe Michael B.
Published: May 2006

We consider utilizing a sequential experiment for estimating the mean of a normal distribution when the variance of the distribution is unknown. For a suitable choice of the design constants of the experiment and for loss structures of practical interest, it is shown that the difference in the expected loss with optional stopping and the expected loss which would be incurred if σ were known is a bounded function of σ.
CONSIDERATIONS OF THE CONCEPT OF STRUCTURAL HOMOLOGY AS APPLIED TO BOVINE CARBOXYPEPTIDASES A AND B
Authors: Bradshaw Ralph A. , Neurath Hans , Walsh Kenneth A.
Published: May 2006

An argument is presented in favor of the hypothesis that, bovine carboxypeptidases A and B fit by and large, the concept of homology on the levels of both amino acid sequence and three-dimensional structure. Two peptide sequences from carboxypeptidases A and B, comprising 46 amino acid residues, display structural homology to the extent of 51 per cent. One of the two peptides contains two of the amino acid residues which have been identified by X-ray crystallography as zinc ligands in carboxypeptidase A. The same residues are conserved in carboxypeptidase B in a loop of comparable dimensions. The other homologous pair of amino acid sequences appears to occur in different regions of the two enzymes which include in carboxypeptidase B the cysteinyl residue proposed to function as the third zinc ligand but not the amino acid residue believed to be the analogous ligand in carboxypeptidase A. The uncertainties of this prediction are considered in the light of existing chemical and structural evidence.
INTERACTION OF INSULIN WITH THE CELL MEMBRANE: THE PRIMARY ACTION OF INSULIN
Authors: Cuatrecasas Pedro
Published: May 2006

Insulin can be covalently attached to a large polymers of Sepharose through the α-amino group of the N-terminal residue of the B chain, or through the ε-amino group of its lysyl residue. Such derivatives effectively increase the utilization of glucose, and suppress the hormone-stimulated lipolysis, of isolated fat cells. The effects occur with concentrations of insulin-Sepharose that are nearly as low as those of native insulin, and the maximal responses are the same. The results indicate that interaction of insulin with superficial membrane structures alone may suffice to initiate transport as well as other metabolic alterations.
HOST SPECIFICITY OF DNA PRODUCED BY
Escherichia coli
, XI.
In vitro
MODIFICATION OF PHAGE FD REPLICATIVE FORM
Authors: Kühnlein Urs , Linn Stuart , Arber Werner
Published: May 2006

An enzymatic activity, having the properties expected of a B-specific host-controlled modification enzyme, has been purified from an extract of
Escherichia coli
strain B. This activity renders the unmodified replicative form of phage fd resistant to B-specific restriction and is only present in strains carrying intact genes for type B modification. In phosphate buffer, the enzyme acts optimally at pH 6 and is dependent upon a single cofactor, S-adenosylmethionine.
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY:
13
C SPECTRA OF UNSUBSTITUTED INOSITOLS
Authors: Dorman Douglas E. , Angyal S. J. , Roberts J. D.
Published: May 2006

The chemical shifts of
13
C in natural abundance have been obtained from nuclear magnetic resonance spectra of
scyllo-, myo-, chiro-
, and
epi
-inositols at 15.1 MHz. A set of empirical substitutent parameters were derived and shown to be moderately successful in correlating the
13
C resonance-line positions for these substances. The substituent parameters conform generally to the idea that steric hindrance or porximity effects are of special importance in influencing chemical shifts of carbons in cyclohexane systems.
PHOTORESPIRATORY-INDUCED SENESCENCE OF PLANTS UNDER CONDITIONS OF LOW CARBON DIOXIDE
Authors: Widholm Jack M. , Ogren William L.
Published: May 2006

A light-induced senescence of soybeans at low carbon dioxide concentration has been characterized and ascribed to photorespiration. It is suggested that this system can be used to screen large numbers of plants for photorespiratory-deficient individuals of photorespiratory species. Optimal conditions for this senescence include a low CO
2
concentration, a temperature near 34°, high light intensity, and a high oxygen concentration.
ESTROGEN “RECEPTORS” IN BRAIN: AN UNSOLVED PROBLEM
Authors: Whalen Richard E. , Maurer Richard A.
Published: May 2006

Various investigators have postulated that estrogen-sensitive structures contain “receptors” which accumulate and bind estradiol. Further, it has been implied that brain receptors function in a similar way to uterine receptors, even though the evidence for this conclusion is not strong. The present study was designed to compare the accumulation of radioactivity by brain and uterus following
3
H-estradiol treatment in estrous, diestrous, and ovariectomized rats. Uterus exhibited high levels of radioactivity in diestrus, but not in estrus or the ovariectomized condition. The accumulation of hormone by brain did not fluctuate with the various levels of endogenous hormone stimulation, but rather showed a pattern of uptake similar to muscle, a nontarget tissue. It was concluded that if brain hormone receptors exist, they do not respond to estradiol as do uterine receptors.
A BACTERIUM CAPABLE OF USING PHYTOL AS ITS SOLE CARBON SOURCE, ISOLATED FROM ALGAL SEDIMENT OF MUD LAKE, FLORIDA
Authors: Hoag K. B. , Bradley W. H. , Tousimis A. J. , Price D. L.
Published: May 2006

A species of
Flavobacterium
that consistently attacks pure phytol and can use it as a sole source of carbon has been isolated from the blue-green algal sediment of Mud Lake, Florida. Biochemical tests demonstrate that this bacterium also readily uses various other organic compounds. This bacterium may account for the degradation products of chlorophyll and its side chain phytol, which have been found in the Mud Lake algal sediment. Phytol and its degradation products play a role in Refsum's disease, but phytol is also the most promising precursor of the isoprenoid hydrocarbons found in oil shale of the Green River Formation (Eocene) of Colorado, Utah, and Wyoming.

The discovery of this species of
Flavobacterium
is a significant product of a protracted study of the bacteriology, phycology, zoology, and geochemistry of the algal sediment forming in Mud Lake, which is believed to be a modern analogue of the kind of algal sediment that, through geologic time, became oil shale.
AMINO ACID SEQUENCE OF BOVINE THYROCALCITONIN
Authors: Brewer H. Bryan , Ronan Rosemary
Published: May 2006

Bovine thyrocalcitonin has been isolated in homogeneous form, and its complete amino acid sequence determined. The bovine hormone is a singlechain 32 amino acid polypeptide. It contains a 1-7 amino terminal disulfide bridge, and the carboxyl terminal amino acid is prolinamide. The bovine thyrocalcitonin sequence differs from the porcine sequence by three amino acid residues and from the human sequence by 18 amino acid residues.
HOMOGENEOUS CATALOGS OF EARTHQUAKES
Authors: Knopoff Leon , Gardner J. K.
Published: May 2006

The usual bias in earthquake catalogs against shocks of small magnitudes can be removed by testing the randomness of the magnitudes of successive shocks. The southern California catalog, 1933-1967, is found to be unbiased in the sense of the test at magnitude 4 or above; the cutoff is improved to
M
= 3 for the subcatalog 1953-1967.
CONJUGATE POINTS OF SECOND-ORDER LINEAR DIFFERENTIAL EQUATIONS
Authors: Leighton Walter
Published: May 2006

The paper of which the present article is itself an abstract is concerned with locating zeros of nonnull solutions of differential systems of the formcplx=fwhere
r
(x) and
p
(x) are continous and
r
(x) is positive for x ≥ a. When
r
(x) = 1 and
p
(x) = αx + β, necessary conditions and sufficient conditions are pro-vided that the interval (a,b] contain
n
zeros. The results are, of course, of importanceconsiderably beyond the case when
p
(x) is linear.
A NONDEFECTIVE (COMPETENT) ADENOVIRUS-SV40 HYBRID ISOLATED FROM THE AD.2-SV40 HYBRID POPULATION
Authors: Lewis Andrew M. , Levin Myron J. , Wiese William H. , Crumpacker Clyde S. , Henry Patrick H.
Published: May 2006

A new nondefective hybrid virus has been plaque-isolated from the Ad.2-SV40 hybrid population. This virus replicates efficiently with one-hit kinetics in both human embryonic kidney and African green monkey kidney cells, induces an SV40 specific antigen which is detectable by immunofluorescence and complement-fixation using sera from SV40 tumor-bearing hamsters, and produces SV40-specific RNA detectable by DNA-RNA hybridization. The SV40-specific antigen induced by this virus is heat-stable, sensitive to inhibitors of DNA synthesis, serologically different from SV40 T and viral antigens, and is an unrecognized SV40 antigen.
ALKALINE PH DEPENDENCE OF δCHYMOTRYPSIN-CATALYZED HYDROLYSIS OF SPECIFIC SUBSTRATES
Authors: Valenzuela Pablo , Bender Myron L.
Published: May 2006

K
m

(app) and
k
cat
for the δchymotrypsin-catalyzed hydrolysis of
N
-acetyl-L-tryptophan methyl ester and
N
-furylacryloyl-L-tryptophanamide were measured as a function of pH and ionic strength. The

K
m

(app) values do not increase considerably above pH 9 for δ-chymotrypsin, as is the case with α-chymotrypsin. The observed kinetic difference between both enzymes at high pH suggests that the reversible inactivation of α-chymotrypsin at alkaline pH may involve the participation of tyrosine 146 or alanine 149 since both residues are present as chain termini in α-chymotrypsin but not in δ-chymotrypsin.
INDUCTION OF EUGLENA TRANSFER RNA'S BY LIGHT
Authors: Barnett W. Edgar , Pennington C. J. , Fairfield S. A.
Published: May 2006

Exposure of dark-grown, wild-type
Euglena gracilis
to light induces the formation of at least three new chromatographic species of tRNA. Parallel studies with a bleached mutant (W
3
BUL) of
Euglena
demonstrate that the induction of these new tRNA species is dependent upon the cell's ability to form chloroplasts and rule out the possibility that the new species arise from an effect of light on the tRNA's
per se
.
EVIDENCE FOR MULTIPLE GENE CONTROL OF A SINGLE POLYPEPTIDE CHAIN: THE HEAVY CHAIN OF RABBIT IMMUNOGLOBULIN
Authors: Koshland Marian Elliott , Davis Judith J. , Fujita N. Joan
Published: May 2006

To determine the chemical basis for rabbit heavy chain allotypes, amino acid analyses were carried out on IgG and IgM antibodies isolated from rabbits which were homozygous a1 or a3 for the γ chain locus and homozygous b4 for the light chain locus. The compositional differences between a1 and a3 IgM antibodies were found to be identical to those between their IgG counterparts. The identity of the allotypic amino acid replacements showed that the same genetic markers were present in the variable sequences of IgG and IgM heavy chains. Since the constant sequences of these heavy chains are controlled by different loci, these data demonstrated that rabbit heavy chains are coded by two separate germ-line genes, one producing the variable region and a second one of various genes producing the constant regions.

The use of two antibodies, antiazophenylarsonate and antiazophenyl-β-lactoside, permitted the compositions to be compared also on the basic of immunological specificity. The specificity amino acid replacements were found to be identical in the IgM and IgG heavy chains whether the two antibodies were isolated from and individual animal of a1 or a3 allotype. These results further support the conclusions of the allotype measurements that at least two genes code for the rabbit heavy chain.
ACETYL COA CARBOXYLASE, II. DEMONSTRATION OF BIOTIN-PROTEIN AND BIOTIN CARBOXYLASE SUBUNITS
Authors: Alberts Alfred W. , Nervi A. M. , Vagelos P. R.
Published: May 2006

Previous work has shown that
Escherichia coli
acetyl CoA carboxylase is composed of two dissimilar protein components, E

a

which contains covalently bound biotin and forms E

a

-CO
2
-from HCO
3
- and ATP, and E

b

which is involved in the transfer of the carboxyl group from E

a

-CO
2
- to acetyl CoA, forming malonyl CoA. E

a

has been dissociated into two subunits at pH 9. One subunit, designated biotin carboxylase, catalyzes a model reaction, the ATP-dependent carboxylation of free (+)-biotin. The other subunit contains covalently bound which is carboxylated by the biotin carboxylase in the course of acetyl CoA carboxylation.
PEPTIDYL TRANSFERS IN GRAMICIDIN S BIOSYNTHESIS FROM ENZYME-BOUND THIOESTER INTERMEDIATES
Authors: Gevers Wieland , Kleinkauf Horst , Lipmann Fritz
Published: May 2006

The biosynthesis of the peptide antibiotic gramicidin S involves successive peptidyl transfer reactions between intermediates bound in thioester linkages to two active enzyme fractions, I and II. Fraction II activates and recemizes phenylalanine, and then initiates peptidyl transfer by catalyzing a reaction between the carboxyl group of D-phenylalanine, bound to an enzymic sulfhydryl group, and the free imino group of L-proline, one of four L-amino acids all linked by their carboxyl functions to separate sulfhydryl groups on fraction I. Successive reactions of this type in the active centers of the multienzyme complex of fraction I lead to the formation of thioester-bonded nascent peptide chains and, ultimately, of the antibiotic product.
TRANSFER RNA: A COMPARISON BY GEL ELECTROPHORESIS OF THE TRNA IN HELA CYTOPLASM, HELA MITOCHONDRIAL FRACTION, AND
E. coli
Authors: Knight E. , Sugiyama T.
Published: May 2006

A class of transfer RNA separable from the majority of transfer RNA by gel electrophoresis has been observed in
E. coli
and in the mitochondrial fraction of HeLa cells but not in HeLa cytoplasm. The size of this class of transfer RNA, as judged by its mobility on polyacrylamide gel, is intermediate between the major part of the transfer RNA and 5
S
RNA. It exists in part associated with the ribosomes, and its amino acid acceptor activity is different from the major class of transfer RNA.
NOREPINEPHRINE-INDUCED DEPOLARIZATION OF BROWN FAT CELLS
Authors: Horwitz B. A. , Horowitz J. M. , Smith R. Em.
Published: May 2006

Intracellular potentials of brown fat cells in lightly anesthetized cold-acclimated rats were measured
in vivo
. The effects of adrenergic agonists and antagonists on these potentials were examined in an attempt to relate the electrical activity of the cells to the adrenergic-induced stimulation of brown fat thermogenesis.

Norepinephrine, the physiological mediator of brown fat heat production, significantly depolarized the membrane of these cells
in vivo
. This was effected either upon norepinephrine administration (3-100 μg/kg body wt) or excitation of the transsected nerve trunk to the interscapular fat pad and appreciably inhibited (55%) by doses of propranolol (1 mg/kg) sufficient to abolish the temperature increase of the tissue. Since theophylline (325 μm/kg) did not depolarize the cells, although it stimulated thermogenesis in the tissue, the depolarizing effect of norepinephrine is interpreted as being at least partially associated with biochemical events terminating in the activation of adenylate cyclase. However, the norepinephrine-induced electrical changes and the ensuing increase in brown fat thermogenesis appear to be causally independent and experimentally separable. On the other hand, our data do not preclude the speculation that the membrane phenomenon, if accompanied by increased Na
+
, may serve partially to regulate the metabolic rate of brown fat during long-term physiological stimulation (e.g., cold stress) by increasing the rate of ATP utilization via the Na
+
/K
+
pump.
EFFECT OF D
2
O ON THE CARBOXYPEPTIDASE-CATALYZED HYDROLYSIS OF
O
-(
trans
-CINNAMOYL)-L-β-PHENYLLACTATE AND N-(N-BENZOYLGLYCYL)-L-PHENYLALANINE
Authors: Kaiser B. L. , Kaiser E. T.
Published: May 2006

Solvent isotope effects have been examined for the action of the zinc-containing metalloenzyme carboxypeptidase A on ester and peptide substrates. The kinetic parameters for the carboxypeptidase-catalyzed hydrolysis of an ester,
O
-(
trans
-cinnamoyl)-L-β-phenyllactate, in 0.05
M
Tris-DCl buffer containing 0.5
M
NaCl at pD 8.07 and 25° were compared with those obtained from measurements done in 0.05
M
Tris-HCl buffer containing 0.5
M
NaCl at pH 7.52 and 25°. A (
k
cat
)

H
2
O

/(
k
cat
)

D
2
O

ratio of approximately 2 was obtained. The value of the Michaelis constant

K
m

was unaffected by the change in solvent as was the inhibition constant,

K
i

, found for the product, L-β-phenyllactate, which is a competitive inhibitor. These results indicate that a catalytic step involving general base catalysis is probably important in the carboxypeptidase-catalyzed hydrolysis of an ester. A similar set of experiments carried out on the peptide substrate, N-(N-benzoylglycyl)-L-phenylalanine gave ambiguous results. The role of the zinc ion in the catalytic action of carboxypeptidase A can be considered in the light of these findings.
AN IMPROVED ITERATION METHOD FOR THE CALCULATION OF SURFACE TENSION USING THE SIGNIFICANT STRUCTURE THEORY OF LIQUIDS
Authors: Jhon Mu Shik , Eyring Henry
Published: May 2006

An improved iteration method for calculating the surface tension developed by Chang
et al
. is presented. To test it, the surface tensions of the following liquids are calculated: A, N
2
, CH
4
, PH
2
, Br
2
, C
6
H
6
, HgCl
2
, and TiCl
4
.

The calculated results show the present method is an improvement over that of Chang
et al
. In addition to the change in the energy of sublimation of a molecule in a surface layer, which Chang
et al
. considered, the less important but not negligible effects on the number of nearest neighbors, η

i

, and the characteristic temperature, θ

i

, are now included. η

i

is proportional to the effective local density, and θ

i

is proportional to the square root of the effective local density. The calculated values fit the experimental data somewhat more closely than those calculated by the original method of Chang
et al
.
AUXIN AND GROWTH OF EXCISED ROOTS OF
Bryophyllum calycinum
Authors: Robbins William J. , Hervey Annette
Published: May 2006

Exogenous auxin (α-naphthalene acetic acid, indole acetic acid, or 2,4-dichlorophenoxyacetic acid) was essential for the growth of single excised root tips of
Bryophyllum calycinum
in 50 ml of a mineral salt-sucrose medium supplemented with vitamins. Large inocula with a dry weight of 2.0 mg or more grew with no auxin added to the medium. Evidence for the synthesis of auxin by the excised roots grown from the larger inocula is presented. Leaching of auxin from single root tips cultivated in 15 or 50 ml of basal medium is considered to account for their failure to grow.
AXOPLASMIC TRANSPORT IN THE CRAYFISH NERVE CORD
Authors: Fernandez H. L. , Davison P. F.
Published: May 2006

Axoplasmic proteins in the crayfish nerve cord were labeled by the incorporation of high specific activity
3
H-leucine that was injected into one of the abdominal ganglia. The labeled proteins moved caudad as a sharply defined peak at 1.1 mm/day. The level of radioactivity in the cord decreased slowly as the peak approached the tail. From the sharpness of the peak and the low decrement of label with distance it is deduced that the axoplasm is probably a gel, and some of it is not consumed as it is transported along the axon but reaches the terminal and, perhaps, the synaptic regions.
A MODEL RELATING GENE REPLICAS AND GENE REPRESSION TO PHENOTYPIC EXPRESSION AND VARIABILITY
Authors: Rendel J. M.
Published: May 2006

It is suggested that the development of a dominant character in higher organisms starts with the activation of a major gene. This gene replicates; the number of replicas is controlled by a second gene or set of genes, which also ensure that the most suitable allele, if more than one is present, makes the replicas. The major gene replicas then make messenger RNA and are reinforced in this by minor genes. The joint product of major gene replicas and minor genes activates a fourth gene or set of genes which produce a repressor that damps down the activity of the major gene replicas. The evidence for this scheme, which comes from studies of selection experiments in populations, is summarized and the evidence from studies of DNA and RNA metabolism is referred to in this paper.
RIBOSOMAL RNA GENES IN BACTERIA: EVIDENCE FOR THE NATURE OF THE PHYSICAL LINKAGE BETWEEN 16S AND 23S RNA GENES
Bacillus subtilis
Authors: Colli W. , Oishi M.
Published: May 2006

The nature of the arrangement of 16
S
and 23
S
ribosomal RNA genes on the
Bacillus subtilis
chromosome was studied by means of a Cs
2
SO
4
density gradient centrifugation technique after complexing DNA-(ribosomal) RNA hybrids with mercuric ions. It was observed that the same fragments of single-stranded DNA with an average molecular weight of 1.9 × 10
6
which hybridize with 23
S
RNA also hybridize with 16
S
RNA. This indicates that genes for both these species of ribosomal RNA are physically linked on such DNA fragments. Some evidence suggests that the two types of genes are interspersed with each other, perhaps in sets, each of which contains a 16
S
and a 23
S
ribosomal RNA gene.
A CONCEPT OF THREE LIGHT REACTIONS IN PHOTOSYNTHESIS BY GREEN PLANTS
Authors: Knaff David B. , Arnon Daniel I.
Published: May 2006

It has generally been accepted that plant photosynthesis involves two light reactions, one that proceeds best in short-wavelength light and is identified with oxygen evolution (System II) and another that proceeds best in long-wavelength light and is identified with a cycle electron flow (System I). This paper presents a concept of three light reactions in photosynthesis, based on new evidence that System II comprises two rather than one short-wavelength light reaction. These appear to operate in series and to be connected by an electron transport chain peculiar to System II. Parallel to System II is the long-wavelength light reaction of System I.
NEURONAL TUMOR CELLS WITH EXCITABLE MEMBRANES GROWN
in vitro
Authors: Nelson Phillip , Ruffner Winfred , Nirenberg Marshall
Published: May 2006

Mouse neuroblastoma cells grown
in vitro
are capable of generating action potentials in response to electrical stimulation. A wide spectrum of responses was observed with different cells ranging from passive responses to action potentials. A hypothesis is proposed concerning the acquisition of electrical excitability as neuroblasts mature into neurons.
In vitro
FORMATION OF AN ACTIVE MULTIENZYME COMPLEX IN THE TRYPTOPHAN PATHWAY OF
Neurospora crassa
Authors: Arroyo-Begovich Angel , DeMoss John A.
Published: May 2006

A multienzyme complex that catalyzes the anthranilate synthetase, phosphoribosylanthranilate (PRA) isomerase, and indoleglycerolphosphate (InGP) synthetase reactions was produced
in vitro
when extracts from a
tryp-1
mutant and a
tryp-2
mutant of
Neurospora crassa
were mixed. The sedimentation values and the molecular weights for the interacting components obtained from the mutants were estimated by sucrose gradients and by gel filtration on Sephadex columns. The component coded for by the tryp-2 gene (
a
-component) which is present in the
tryp-1
-17 mutant has a sedimentation coefficient of 4.5
S
and molecular weight of 70,000. The component coded for by the tryp-1 gene (
i
-component) which is present in the
tryp-2
-6 mutant has a sedimentation coefficient 7.5
S
and a molecular weight of 170,000. The complex formed
in vitro
had similar properties to those previously reported for the wild-type complex. A
Q
10
value of 3 and an apparent activation energy of 18,000 cal/mole were calculated for the formation of the complex from the two components.
RECENT STUDIES ON THE STRUCTURE OF HUMAN SERUM LOW- AND HIGH-DENSITY LIPOPROTEINS
Authors: Gotto Antonio M.
Published: May 2006

Several methods have been recently developed for the preparation of soluble apo-low-density lipoprotein (apoLLL) Delipidation of LDL alters the immunochemical activity of the molecule and causes an apparent increase in random structure. Despite these changes, soluble apoLDL retains prominent immunological and optical characteristics of native LDL. The lipid of LDL appears to stabilize the protein conformation of LDL derivatives. Optical measurements suggest that native LDL contains a significant amount of pleatedsheet, antiparallel chain β-structure in addition to random and probably some helical structure, while HDL, by optical criteria, is relatively richer in the α-helical conformation. Two proteins containing C-terminal glutamine and C-terminal threonine have been isolated from high-density lipoprotein (HDL). Circular dichroic measurements and total amino acid content are consistent with a greater helical content of apoHDL-Thr than apoHDL-Gln. The techniques of nuclear magnetic resonance and electron spin resonance have been used to probe the structure of LDL and HDL. The presence of protein does not seem to exert a constraining effect on the proton resonance of lipoprotein lipids, while the presence of lipid does appreciably constrain nitroxide tumbling in spin-labeled lipoprotein protein, the constraint being relatively greater in HDL than in LDL. Existing structural evidence is consistent with lipoprotein models in which protein and phospholipid occupy the surface and other lipids are more internal.
HEARING IN THE GIANT SEA TURTLE,
Chelonia mydas
Authors: Ridgway Sam H. , Wever Ernest Glen , McCormick James G. , Palin Jerry , Anderson John H.
Published: May 2006

Measurement were made of the cochlear potentials in three specimens of the giant sea turtle,
Chelonia mydas
, in response to both aerial and mechanical stimulation of the ear. The results show maximum sensitivity in the region of 300 to 400 Hz, with a rather rapid decline in sensitivity for lower and especially for higher tones. The upper limit for the observation of cochlear potentials without injury is 2000 Hz, and a practical limit of usefulness of this ear is probably about 1000 Hz.
SUPPRESSION OF T4D LIGASE MUTATIONS BY rIIA AND rIIB MUTATIONS
Authors: Berger Hillard , Kozinski Andrzej W.
Published: May 2006

The introduction of
r
II mutations into polynucleotide ligase
amber
mutants (gene 30) of T4D bacteriophage results in the restoration of phage growth in the nonpermissive host
E. coli
B. When cells are mixedly infected with
r
II
+
-ligase
-
and
r
II-ligase
-
phage, growth is reduced, indicating that the
r
II mutations are recessive to the
r
II
+
alleles. Infection with the
r
II-ligase
-
double mutants results in nearly complete restoration of phage DNA synthesis and prevents the extensive degradation of parental phage DNA observed after infection with ligase
-
single mutants. Similar results are observed when cells are infected with ligase
-
mutants and chloramphenicol is added five minutes post infection.
A MUTATION WHICH CHANGES A MEMBRANE PROTEIN OF
E. coli
Authors: Inouye Masayori , Guthrie J. Peter
Published: May 2006

A temperature-sensitive mutant of
E. coli
, which cannot synthesize DNA at high temperature but can continue cell division, shows a difference in a membrane protein fraction at high temperature by gel electrophoresis. This mutation of a bacterial membrane protein is unique. The protein may link DNA replication and cell division through the membrane.
RARE EARTH IMPURITIES IN YB
6
AND ZRB
12
Authors: Fisk Zachary , Matthias Bernd T. , Corenzwit E.
Published: May 2006

We present data on the depression of the superconducting transition temperatures of YB
6
and ZrB
12
by rare earth impurities. These data show unusual features. Ce in YB
6
is in some ways analogous to Yb in ZrB
12
, and this analogy also appears to hold between Ce in CeB
6
and YB in YbB
12
.