bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of mammalian microRNA expression by in situ hybridization with RNA oligonucleotides
Authors: Deo Monika , Yu Jenn‐Yah , Chung Kwan‐Ho , Tippens Melissa , Turner David L.
Published: May 2006

We have developed an in situ hybridization procedure for the detection of microRNAs (miRNAs) in tissue sections from mouse embryos and adult organs. The method uses highly specific washing conditions for RNA oligonucleotide probes conjugated to a fluorescein hapten. We show that this method detects predominantly mature miRNAs rather than the miRNA precursors or primary transcripts. We have determined expression patterns for several miRNAs expressed in the developing and adult nervous system, including miR‐124a, miR‐9, miR‐92, and miR‐204. Whereas miR‐124a is expressed in neurons, miR‐9 is expressed in neural progenitors and some neurons, and miR‐204 is expressed in the choroid plexus, retinal pigment epithelium, and ciliary body. miR‐204 is located in an intron of the TRPM3 gene, and the TRPM3 mRNA is coexpressed with miR‐204 in the choroid plexus. We also find that primary transcripts for miR‐124a and miR‐9 genes are expressed in patterns similar to their respective mature miRNAs. The ability to visualize expression of specific miRNAs in embryos and tissues should aid studies on miRNA function. Developemental Dynamics 235:2538–2548, 2006. © 2006 Wiley‐Liss, Inc.
Chemical composition, seasonal variation and a new sesquiterpene alcohol from the essential oil of Lippia integrifolia
Authors: del C. Coronel Angelina , Cerda‐García‐Rojas Carlos M. , Joseph‐Nathan Pedro , Catalán César A. N.
Published: May 2006

Chemical investigations on the essential oil of Lippia integrifolia performed by column chromatography, HPLC, GC–MS, 1H‐ and 13C‐NMR spectroscopy led to the identification of 78 components. A new sesquiterpene alcohol, trans‐africanan‐1α‐ol (4), was characterized as a significant component of the oil. Additionally, six samples obtained at monthly intervals through the annual cycle of the shrub (November–April) were studied. The oil was characterized by large amounts of oxygenated sesquiterpenes (53.3–69.4%) and sesquiterpene hydrocarbons (14.3–27.9%), along with small amounts of monoterpenoids (1.4–2.9%). Lippifoli‐1(6)‐en‐5‐one (2), african‐5‐en‐1α‐ol (3), β‐caryophyllene oxide, 4,5‐seco‐africanan‐4,5‐dione (10), trans‐africanan‐1α‐ol (4), humulene epoxide II, integrifolian‐1,5‐dione (1) and lippifoli‐1(6)‐en‐4β‐ol‐5‐one (7) were the main oxygenated constituents. Although the qualitative composition appeared to be constant, there were large quantitative variations in the content of most components through the studied period. Copyright © 2006 John Wiley & Sons, Ltd.
Assessment of gene promoter hypermethylation for detection of cervical neoplasia
Authors: Wisman G. Bea A. , Nijhuis Esther R. , Hoque Mohammad O. , Reesink‐Peters Nathalie , Koning Alice J. , Volders Haukeline H. , Buikema Henk J. , Boezen H. Marike , Hollema Harry , Schuuring Ed , Sidransky David , van der Zee Ate G.J.
Published: May 2006

Current cervical cancer screening is based on morphological assessment of Pap smears and associated with significant false negative and false positive results. Previously, we have shown that detection of hypermethylated genes in cervical scrapings using quantitative methylation‐specific PCR (QMSP) is a promising tool for identification of squamous cell cervical cancer. Aim of the present pilot‐study was to evaluate presence of hypermethylated genes in cervical carcinogenesis, both in squamous cell as well as adenocarcinomas. Cervical scrapings were obtained from 30 patients diagnosed with cervical cancer (20 squamous cell carcinomas and 10 adenocarcinomas) and 19 women with histologically normal cervices. The scraped cells were used for determination of promoter hypermethylation by QMSP for 12 genes and for morphological assessment. Overall, CALCA, DAPK, ESR1, TIMP3, APC and RAR‐β2 promoters were significantly more often hypermethylated in cancers than in controls, while adenocarcinomas were more often hypermethylated above the highest control ratio for APC, TIMP3 and RASSF1A promoters. Combining 4 genes (CALCA, DAPK, ESR1 and APC) yielded a sensitivity of 89% (with all adenocarcinomas identified), equal to cytomorphology (89%) and high‐risk human papilloma virus (Hr‐HPV; 90%). The 4‐gene QMSP proved theoretically superior to cytomorphology as well as Hr‐HPV in specificity (100% vs. 83 and 68%, respectively), because cytology identified 3 controls as moderate or severe dyskaryosis and 6 controls were positive for Hr‐HPV. In conclusions, QMSP of 4 gene promoters combined appears to have comparable sensitivity and potentially better specificity in comparison to “classic” cytomorphological assessment and Hr‐HPV detection. QMSP holds promise as a new diagnostic tool for both squamous cell carcinoma and adenocarcinoma of the cervix. © 2006 Wiley‐Liss, Inc.
Bone‐bonding ability of a hydroxyapatite coated zirconia–alumina nanocomposite with a microporous surface
Authors: Takemoto M. , Fujibayashi S. , Neo M. , Suzuki J. , Kokubo T. , Nakamura T.
Published: May 2006

Using a combination of hydroxyapatite (HA) coating and microporous surface treatment, bone‐bonding ability was given to composites of ceria‐stabilized tetragonal zirconia and alumina (CZA), which possesses excellent mechanical and wear properties and phase stability. Four types of CZA plates (2 × 10 × 15 mm3) were prepared for this study, which were CZA with a polished surface (group 1), a microporous surface prepared by hydrofluoric acid and heat treatment (group 2), a microporous surface with a submicron HA coating prepared by alternately soaking the plate from group 2 in aqueous CaCl2/HCl and Na2HPO4 solutions (group 3), and a microporous surface with a 4‐μm HA coating prepared by the biomimetic method, where the plates from group 3 were soaked in simulated body fluid (group 4). Plates were implanted into rabbit tibia, and after 4, 8, and 16 weeks, tensile testing and histological examination of the bone–implant interface were conducted. At 4 weeks, group 4 had superior bone‐bonding ability compared with other implants, which was maintained at the later postimplantation times. This HA‐coated CZA with a microporous surface has the possibility of clinical use as a bearing material in cementless joint prostheses or as a load‐bearing bone substitute. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Normal and osteopenic bone‐derived osteoblast response to a biomimetic gelatin–calcium phosphate bone cement
Authors: Bigi A. , Panzavolta S. , Sturba L. , Torricelli P. , Fini M. , Giardino R.
Published: May 2006

We have recently developed a new calcium phosphate bone cement enriched with gelatin (GEL‐CP), which exhibits improved mechanical properties with respect to the control cement (C‐CP). In a previous study, we demonstrated the good response of osteoblast‐like cells to the new biomimetic bone cement. Herein, we extend the investigation to primary culture of osteoblasts derived from healthy and pathological bones. Osteoblasts derived from normal (N‐OB) and osteopenic (O‐OB) sheep bones were cultured on samples of GEL‐CP, and their behavior was compared with that of cells cultured on C‐CP as control. Cell morphology, proliferation, and differentiation were evaluated at 3 and 7 days. SEM analysis revealed that both N‐OB and O‐OB showed a normal morphology when cultured on GEL‐CP. Biological tests demonstrated that the gelatin‐enriched cement improves osteoblasts' activity and differentiation of O‐OB cultures, with respect to the control samples. The data indicate that the new composite cement positively stimulates alkaline phosphatase activity, collagen type I, and osteocalcin production, not only in N‐OB, but also in O‐OB culture. The improvement due to the presence of gelatin suggests that the biomimetic composite material could be successfully applied as bone substitute also in the presence of osteopenic bone. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Postictal spectroscopy and imaging findings mimicking brain tumor recurrence
Authors: Hattingen Elke , Franz Kea , Pilatus Ulrich , Weidauer Stefan , Lanfermann Heiner
Published: May 2006

1H magnetic resonance spectroscopic imaging (MRSI) was performed on a patient with an admission diagnosis of recurrent astrocytoma. The patient had undergone surgical resection and radiation therapy for a left occipital astrocytoma WHO grade III 12 years previously, and presented with aphasia, right‐sided hemiparesis, and severe headache. Postcontrast T1‐weighted images showed cortical enhancement of the left parietotemporal lobe near the post‐resection cavity. MRSI revealed a marked increase of trimethylamines (TMA), elevated creatine/creatinephosphate (tCr), and reduced N‐acetyl‐aspartate (tNAA) in the same brain region. The spectroscopic data were consistent with tumor recurrence. However, the pattern of contrast enhancement on magnetic resonance imaging (MRI), evidence of an epileptic focus on electroencephalography (EEG), and spontaneous regression of the symptoms argued against tumor recurrence. In a 4‐week follow‐up, the contrast enhancement disappeared on MRI and the EEG abnormalities and neurological symptoms resolved. Follow‐up spectroscopic data showed a decrease in TMA compared to normal values. The tCr signal remained elevated but returned to normal values after 5 months. In conclusion, postictal neurological deficits with a temporary increase in TMA and tCr were diagnosed. This is the first report of seizure‐induced MRS abnormalities mimicking tumor recurrence. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Obstetric MRI
Authors: Levine Deborah
Published: May 2006

Ultrasound is the imaging modality of choice for pregnant patients. However, MRI is increasingly utilized in patients in whom the sonographic diagnosis is unclear. These include maternal conditions unique to pregnancy such as ectopic pregnancy, placenta accreta, and uterine dehiscence. MRI is also being increasingly utilized in the assessment of abdominopelvic pain in pregnancy, in particular in assessment for appendicitis. Fetal MRI is performed to assess central nervous system (CNS) abnormalities and patients who are considering fetal surgery for conditions such as neural tube defects, congenital diaphragmatic hernia, and masses that obstruct the airway. In the future, functional MRI and fetal volumetry may provide additional information that can aid in our care of complicated pregnancies. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Ion imprinted polymer particles for separation of yttrium from selected lanthanides
Authors: Kala Ramakrishnan , Prasada Rao Talasila
Published: May 2006

Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7‐dichloroquinoline‐8‐ol, 4‐vinylpyridine, styrene, divinylbenzene and 2,2′‐azobisisobutyronitrile in 2‐methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y‐Dy, Y‐Gd and Dy‐Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy‐Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of ˜ 25. Dy‐Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid–liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 ± 0.2 to 65.2 ± 0.2% in a single stage of operation.
Imaging triiodothyronine binding kinetics in rat brain: A model for studies in human subjects
Authors: Greenberg Joel H. , Reivich Martin , Gordon Janice T. , Schoenhoff Monika B. , Patlak Clifford S. , Dratman Mary B.
Published: May 2006

Many lines of evidence indicate a role for thyroid hormones in the expression of cognitive and affective disorders. These conditions constitute a large proportion of the illness burden in the general population. Unfortunately, presently available diagnostic procedures cannot adequately identify these problems. To determine whether imaging studies of thyroid hormone kinetics in brain might be feasible in patients with these disorders, an autoradiographic method for measuring thyroid hormone kinetics was developed. Twenty‐five awake adult rats received high specific activity [125I]‐triiodothyronine (T3*). Brains were obtained at intervals from 5 through 300 min after i.v. hormone administration. Every 5th frozen section was thaw mounted and exposed to film. To determine whether T3 was responsible for the autoradiographic images, the intervening sections were assembled while frozen in regional tissue pools and were extracted and then analyzed by high‐performance liquid chromatography. The results demonstrated that radioactivity was almost entirely due to T3*(∼90%) while small amounts of hormone metabolites, including [125I]iodine accounted for the remainder. Regional concentrations of label in autoradiograms were measured by densitometry in hippocampus (CA1, CA2, CA3, and dentate gyrus), cerebellum (molecular and granular cell layers), caudate nucleus, and amygdala. Unexpectedly and interestingly, the results demonstrated that binding through 5 h was mainly irreversible. Regional values of the net uptake rate constant of T3* or influx constant, Ki, were determined from the time course of the T3* data, showing significant differences among regions. These results suggest that imaging of labeled thyroid hormone ligands by positron emission tomography or single photon emission computed tomography may be feasible and would potentially provide useful information relevant to T3 processing in the brain during a variety of drug and disease‐induced conditions. Synapse 60:212–222, 2006. © 2006 Wiley‐Liss, Inc.
Effect of surface solidification on the emplacement of lava flows on a slope
Authors: Lyman A. W. , Kerr R. C.
Published: May 2006

The emplacement dynamics of lava flows on a slope is investigated using theoretical analyses and laboratory experiments for the case where a fixed volume of lava is rapidly released and propagates downhill as a two‐dimensional flow. When the lava has no internal yield strength, we identify four dynamical flow regimes that can arise: an inertial slumping regime, a horizontal viscous regime, a sloping viscous regime, and a crust yield strength regime that finally stops the flow. When the lava has an internal yield strength, it can also flow in a sloping viscoplastic regime which is accurately predicted by a simple box model that we derive. Our results are applied to predict the propagation downhill of various volumes of two typical lavas: a Hawaiian lava with no internal yield strength and a Mount Etna lava with an internal yield strength. In particular, we find that sloping flows of the Mount Etna lava are stopped by the surface crust strength rather than the internal yield strength.
Summertime aerosol chemical components in the marine boundary layer of the Arctic Ocean
Authors: Xie Zhouqing , Sun Liguang , Blum Joel D. , Huang Yuying , He Wei
Published: May 2006

Samples of aerosols from the marine boundary layer of the Arctic Ocean were collected aboard the R/V Xuelong during summer on the Second Chinese Arctic Research Expedition (July–September 2003). Synchrotron radiation X‐ray fluorescence (SR‐XRF) was used to determine chemical compositions of aerosol particles. Multivariate analysis of the SR‐XRF data resolved a number of components (factors), which, on the basis of their chemical compositions and from their affiliation with specific meteorological flow patterns, were assigned physical meanings. Five factors explaining 94.7% of the total variance were identified. Ship emissions accounted for 35.3% of the variance (factor 1 (F1)) and are loaded significantly with S, Fe, V, and Ni. The total Fe emitted from ships globally was estimated at 8.60 × 106 kg yr−1. Heavy‐metal‐rich factors included 34.0% of the variance (F2 and F3) and were interpreted to be pollution carried into the Arctic Ocean by long‐range transport. Anthropogenic contributions from industrial regions to the Arctic Ocean during the summer vary and depend on the source locations. Air mass backward trajectories indicate that the metals including Hg, Pb, Cu, and Zn come mainly from northern Russia. The third source controlling the chemical compositions of aerosols was sea salt (F4, 12.8%). The role of sea salt decreased from the open sea to areas near pack ice. On the basis of the factor scores of aerosol samples, we infer that chlorine volatilization from sea salt may occur, enhanced by nitrogen and sulfur contamination emitted from ships. Because the global inventories of nitrogen and sulfur for ship exhausts are large, and halogens could have important consequences in possible tropospheric ozone destruction, the role of ships in influencing halogen depression in sea salt should be further investigated. Finally, we also identified a crustal factor (F5, 12.6%) and suggest that crustal elements (e.g., Ca) contaminating sea ice may become reinjected into the atmosphere as windblown aerosols.
Low‐frequency radar sounding investigations of the North Amargosa Desert, Nevada: A potential analog of conductive subsurface environments on Mars
Authors: Heggy Essam , Clifford Stephen M. , Grimm Robert E. , Dinwiddie Cynthia L. , Stamatakos John A. , Gonzalez Sarah H.
Published: May 2006

Theoretical estimates of low‐frequency radar sounding performance and its potential for mapping moist subsurface interfaces in conductive environments on Mars are controversial, with predictions of ultimate penetration depth ranging from a few meters to kilometers. To address this issue, we conducted a broadband electromagnetic field survey in which we combined ground penetrating radar (GPR) operating at multiple low frequencies with the transient electromagnetic method (TEM) to investigate the dependence of radar penetration depth on ground resistivity. Surveys were performed in the frequency range 16–100 MHz at two locations on the northwest margin of the Amargosa Desert, Nevada, where numerous Mars‐analog investigations have been performed. The surveys were conducted on a 20‐m‐high homogenous sand dune and on the flanks of a 20‐m‐high scoria cone and above a buried lava flow. A wet alluvial interface was located at the bottom of each structure. GPR detected the wet alluvium contact at the base of the sand dune, but failed to penetrate to the same depth at the scoria cone under similar residual moisture content. Depths of investigation for both the scoria cone and the buried lava flow were limited to approximately 10 m owing to the presence of conductive inclusions in the first few meters, which are below the radar resolution but dramatically decreased the dynamic of the radar‐backscattered echoes and hence the penetration depth. Absorption models constrained by the TEM data are in good agreement with these observations. Depths of investigation varied weakly with frequency owing to substantial, frequency‐independent absorption.
Cloud formation of particles containing humic‐like substances
Authors: Kokkola H. , Sorjamaa R. , Peräniemi A. , Raatikainen T. , Laaksonen A.
Published: May 2006

Humic like substances (HULIS) are a class of compounds that are suspected to have an effect on cloud droplet activation properties of atmospheric aerosols because they decrease the surface tension of aqueous solutions quite efficiently. Surface active organic compounds have a tendency of concentrating on the surfaces of liquid droplets. If the total amount of surface active compound is small enough, partitioning of the substance on the surface depletes it from the droplet interior, decreasing the Raoult effect and increasing the Kelvin effect. Thus, the surface partitioning causes an increase of the critical supersaturation (Köhler curve maximum), and the effect gets stronger with decreasing size of the cloud condensation nucleus. In this study, the effects of HULIS on the activation of cloud droplets was studied by cloud parcel model calculations. Model results indicate that if the surface partitioning is not taken into account, the number of activated droplets can be highly overestimated. The simulations were made using particles containing 10–80% mass fraction of HULIS, while the remaining fraction of the particle was ammonium sulfate. The calculations indicated that the surface tension effects of humic‐like compounds on the cloud activation become significant only when the weight fraction of the organics is very high. In contrast, if the surface partitioning is not taken into account, already a small weight fraction of organics will lead to significant increase in number of cloud droplets.
Carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor thin-film structures
Authors: Gareev R. R. , Bugoslavsky Yu. V. , Schreiber R. , Paul A. , Sperl M. , Döppe M.
Published: May 2006

We report on the carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor insulating-type thin-film structures prepared using sequential deposition at Tg=520K with subsequent annealing at Tg. In the resulting films Mn and Fe are diffused in the Ge matrix without compromising the epitaxial structure. The anomalous Hall effect serves as a manifestation of the carrier-induced magnetism, with p-type conductivity and the Curie temperature TC=209K. The additional doping with Fe stabilizes epitaxial growth and carrier-mediated magnetism at levels of magnetic doping exceeding 10%. We conclude that indirect ferromagnetic exchange is mediated by localized holes with concentration n∼1020cm−3 and mobility μ∼10cm2∕(Vs).
Influence of processing conditions on the stability of poly(3-hexylthiophene)-based field-effect transistors
Authors: Majewski L. A. , Kingsley J. W. , Balocco C. , Song A. M.
Published: May 2006

Bottom-contact organic field-effect transistors (OFETs) based on poly(3-hexylthiophene)-2,5-diyl were fabricated under different process conditions. The devices displayed drastic differences in their ambient-air stability. Whereas it took only about 10min in air for the off current to increase by one order of magnitude in OFETs prepared with chloroform and hexamethyldisilazane, a 120min exposure to air caused only a slight degradation of OFETs prepared using 1,2,4-trichlorobenzene, n-octadecyltrichlorosilane, and a heat treatment. The differences in the film surface morphology were analyzed and possible mechanisms for the enhanced stability are discussed.
Modelling the effects of distance on the probability of fire detection from lookouts
Authors: Rego Francisco Castro , Catry Filipe Xavier
Published: May 2006

In the management of forest fires, early detection and fast response are known to be the two major actions that limit both fire loss and fire-associated costs. There are several inter-related factors that are crucial in producing an efficient fire detection system: the strategic placement and networking of lookout towers, the knowledge of the fire detection radius for lookout observers at a given location and the ability to produce visibility maps. This study proposes a new methodology in the field of forest fire management, using the widely accepted Fire Detection Function Model to evaluate the effect of distance and other variables on the probability that an object is detected by an observer. In spite of the known variability, the model seems robust when applied to a wide variety of situations, and the results obtained for the effective detection radius (13.4 km for poor conditions and 20.6 km for good conditions) are in general agreement with those proposed by other authors. We encourage the application of the new approach in the evaluation or planning of lookout networks, in addition to other integrated systems used in fire detection.
Bending a membrane: How clathrin affects budding
Authors: Hinrichsen Lars , Meyerholz Anika , Groos Stephanie , Ungewickell Ernst J.
Published: May 2006

Receptor-mediated endocytosis of ligands, such as transferrin and LDL, is suppressed when clathrin synthesis is blocked by RNA interference in HeLa cells. We have found that domains containing the adapter complex 2 (AP2)-coated vesicle adapter and the endocytic accessory proteins CALM (clathrin assembly lymphoid myeloid leukemia protein), epsin, and eps15/eps15R (EGF receptor pathway substrate 15-related) nevertheless persist at the plasma membrane. They are similar in size and number to those seen in clathrin-expressing cells. Here we characterize these membrane domains by fluorescence and electron microscopy in detail. Fluorescence recovery after photobleaching measurements suggest that the exchange between membrane-bound and free cytosolic AP2 molecules is not significantly influenced by the depletion of clathrin. The AP2 membrane domains are dispersed upon interfering with protein–protein interactions that involve the α appendage domain of AP2. Electron microscopy of cellular cortices revealed that the AP2 membrane domains lack any curvature, suggesting that clathrin is essential for driving coated pit invagination. A model for coated vesicle formation, incorporating a mechanism commonly referred to as a “Brownian ratchet,” is consistent with our observations.
ARTIFICIAL AND NATURAL SELECTION FOR TWO BEHAVIORAL TRAITS IN DROSOPHILA PSEUDOOBSCURA
Authors: Dobzhansky Theodosius , Spassky Boris
Published: May 2006

In an attempt to elucidate the genetic architecture of two behavioral traits, populations of
Drosophila pseudoobscura
were selected for positive and for negative phototaxis and geotaxis.

The selected populations diverged rapidly in their behavior (Figs. 1 and 2). The selection was relaxed after 20 generations in the phototactic, and after 30 generations in the geotactic populations. The relaxation resulted in convergence almost as rapid as was the divergence under selection. The average phototactic and geotactic neutrality of natural populations is an adaptive trait protected by genetic homeostasis. This does not preclude rapid responses to artificial, and presumably to natural, selection.
RESTRICTED REJOINING OF CHROMOSOMAL SUBUNITS IN ABERRATION FORMATION: A TEST FOR SUBUNIT DISSIMILARITY
Authors: Brewen J. G. , Peacock W. J.
Published: May 2006

The chromosomal subunits that segregate from each other during chromosome replication are shown to be uniquely different. An analysis of tritiated thymidine labeled chromosomal subunits in dicentric chromosomes, generated by isolocus breakage followed by proximal reunion, shows that the end-to-end association of the subunits is not random but is strictly preferential. The data suggest that the functional subunit in the formation of these particular chromosomal aberrations might be single polynucleotide chains of deoxyribonucleic acid, although other molecular species cannot be disregarded. The suggestion that the DNA is the molecule that is involved is based on the fact that the two chains of the DNA double helix exhibit reverse polarity and this property predicts the observed autoradiographic patterns.
THE RELATIONSHIP OF DNA REPLICATION TO THE CONTROL OF PROTEIN SYNTHESIS IN PROTOPLASTS OF T4-INFECTED
Escherichia coli
B
Authors: Lembach Kenneth J. , Kuninaka Akira , Buchanan John M.
Published: May 2006

The relationship of DNA replication to the control of early enzyme synthesis and the formation of late proteins was studied in protoplasts of
E. coli
B cells infected with an
amber
mutant, T4
am
130. In this phage-host system the bacterial DNA is not completely degraded, and the onset and the extent of phage DNA synthesis could be regulated by use of 5-fluorodeoxyuridine and thymidine. It was found that DNA replication is necessary for the transcription of “late” regions of the phage genome and, thus, for the synthesis of late proteins. In addition, the sustained synthesis of late RNA and the tail-fiber protein was shown to require the continued replication of DNA. Furthermore, the mechanism regulating the cessation of early enzyme synthesis appeared to become operative shortly after the onset of DNA replication and required a limited amount of DNA synthesis for its full expression.
SOLUBILIZATION OF PARTICULATE PROTEINS AND NONELECTROLYTES BY CHAOTROPIC AGENTS
Authors: Hatefi Y. , Hanstein W. G.
Published: May 2006

Chaotropic ions (those ions which favor the transfer of apolar groups to water) provide a highly effective means for the resolution of membranes and multicomponent enzymes and for increasing the water solubility of particular proteins and nonelectrolytes. The action of chaotropic agents is related to their effect on the structure and lipophilicity of water.
BIRADICAL SPIN LABELING FOR NERVE MEMBRANES
Authors: Calvin M. , Wang H. H. , Entine G. , Gill D. , Ferruti P. , Harpold M. A. , Klein M. P.
Published: May 2006

We have explored the behavior of pair interaction in a suitable biradical when it is bound by van der Waals' forces in a nerve membrane. We have concomitantly examined a set of model solvents to represent this situation. It appears that the biradical suffers a restriction of internal motion with a minimal restraint on its external motion in the nerve medium. The biradical is so situated as not to respond to the passage of the action potential.
L-URIDINE: SYNTHESIS AND BEHAVIOR AS ENZYME SUBSTRATE
Authors: Wu Anna Fang , Chargaff Erwin
Published: May 2006

L-Uridine, the enantiomer of the normal RNA constituent D-uridine, was synthesized from L-ribose through coupling with bis(trimethylsilyl)-uracil. The synthetic product had the expected chemical and physical characteristics. When used as the acceptor for phosphate transfer by the nucleoside phosphotransferase of carrot, L-uridine is converted to 5′-L-uridylic acid. The Michaelis constants

K
m

are 28 × 10
-3
M
for L-uridine, 5 × 10
-3
M
for D-uridine. The nucleoside phosphotransferase of human prostate, which phosphorylates D-uridine in the 5′, 3′, or 2′ positions, fails to transfer phosphate to the 2′ position of L-uridine, but does produce 5′-and 3′-L-uridylic acids.
DIABETES MELLITUS AND AGING: DIMINISHED PLATING EFFICIENCY OF CULTURED HUMAN FIBROBLASTS
Authors: Goldstein Samuel , Littlefield John W. , Soeldner J. Stuart
Published: May 2006

This work concerns the effect of age and the diabetic gene(s) on the growth capacity of skin fibroblasts in culture. Cells from normal subjects and the progeny of conjugal diabetics have similar lifespans after multiple passages in mass culture. The combined lifespans
in vitro
are inversely proportional to the age of the donor. When individual cells are plated, more of those from normal subjects are able to form colonies. The difference in plating efficiency is apparent when first tested after 20 generations of growth, persists at 30 and 40 generations, but disappears after 50 generations. This cell culture system should be useful in studying the inheritance of the diabetic gene(s), the pathogenesis of the diabetic state, and the relationship between aging and diabetes, both of which decrease plating efficiency.
RADICAL TRANSFORMATION IN IRRADIATED DNA AND ITS CONSTITUENTS
Authors: Herak J. N. , Galogaza V.
Published: May 2006

Electron spin resonance spectroscopy has been used to study transformation of radicals in DNA and a number of its constituents. It was found that in all the bases irradiated at 77°K, hydrogen-addition radicals were formed on warming. The following mechanism of radical transformation has been proposed: damaged species, probably ion-radicals, release hydrogen atoms on warming, which then add to the undamaged bases, preferentially thymine. Thymine need not be the place of the primary damage.
CROSS-BRIDGE PROPERTIES DERIVED FROM MUSCLE ISOTONIC VELOCITY TRANSIENTS
Authors: Podolsky R. J. , Nolan A. C. , Zaveler S. A.
Published: May 2006

The rate constants for the turnover of cross-bridges during frog muscle contraction were determined from an analysis of the motion that follows step decreases in load. For a given projection from the myosin filament, there appears to be a range of about 100 Å along the length of the filament over which the projection can attach to the actin filament and form a cross-bridge. The site of attachment is then displaced by a distance of this same order before the link is broken. The values of the rate constants also imply that a cross-bridge is formed each time an actin site comes within range of a myosin projection, so that the turnover of cross-bridges for a given contraction distance is independent of the speed of the motion.
STRUCTURE OF THE PEPTIDOGLYCAN OF BACTERIAL SPORES: OCCURRENCE OF THE LACTAM OF MURAMIC ACID
Authors: Warth A. D. , Strominger J. L.
Published: May 2006

Six major oligosaccharides were released from the peptidoglycan of spores of
Bacillus subtilis
by lysozyme treatment. They were isolated and characterized as a disaccharide, tetrasaccharide, and hexasaccharide composed of equal amounts of muramic acid and glucosamine and containing two, three, and four acetyl groups, respectively. Three of the compounds were substituted by a single L-alanine residue, and the other three by a single tetrapeptide substituent on the acetylmuramic acid residue at the reducing end of each compound. The other muramic acid residue in the tetrasaccharides (and two of the three in the hexasaccharides) were shown to be present as muramic lactams, a sugar not previously found in nature and, hence, a unique spore constituent. Other features of the structure of spore peptidoglycan are discussed.
PRELIMINARY ANALYSIS OF THE REQUIREMENTS FOR FUSION FROM WITHIN AND FUSION FROM WITHOUT BY NEWCASTLE DISEASE VIRUS
Authors: Bratt Michael A. , Gallaher William R.
Published: May 2006

Different strains of Newcastle disease virus vary in their ability to induce cell fusion. When administered to cells at high multiplicities of infection some strains induce cell fusion within three hours. This type of fusion is apparently caused by the virus particles in the inoculum, since it can be induced by noninfectious virus and does not require protein synthesis for induction. It has been designated fusion from without (FFWO). Other strains induce fusion mainly at low multiplicities of infection. This fusion is induced only by infectious virus, and requires protein synthesis for induction. Probably included among these required proteins is a viral antigen which must be available at the cell surface in order for fusion to occur. This type of fusion has been designated fusion from within (FFWI).
ESTEROLYTIC ACTIVITY OF ELASTASE
Authors: Geneste Patrick , Bender Myron L.
Published: May 2006

The esters of L-alanine were found to be excellent substrates for elastase. The pH-dependence study using two methyl esters of this substrate showed the participation in the mechanism of an ionizing group with an apparent pK of 6.85 and a decrease of the activity at pH's greater than 10 (that could correspond to an apparent pK of 11.4).
STEREOCHEMISTRY OF NUCLEIC ACIDS AND THEIR CONSTITUENTS, XI. THE CONFORMATION OF THE ANTIBIOTIC PUROMYCIN DIHYDROCHLORIDE PENTAHYDRATE
Authors: Sundaralingam M. , Arora S. K.
Published: May 2006

The elucidation of puromycin structure represents the first case where both a nucleic acid and a protein fragment are found together in a crystal. The molecule displays an elongated conformation with the nucleoside and the
p
-methoxy-L-phenylalanine in the preferred conformation. The purine and the tyrosine rings form alternating stacks with interplanar spacings of 3.4 Å. The inhibitory effect of this antiobiotic may be due, in part, to its unique conformation and the ability of the amide proton on N(3′) to hydrogen bond to the active site of the ribosomal enzyme, peptide synthetase.
EVIDENCE THAT XERODERMA PIGMENTOSUM CELLS DO NOT PERFORM THE FIRST STEP IN THE REPAIR OF ULTRAVIOLET DAMAGE TO THEIR DNA
Authors: Setlow R. B. , Regan James D. , German James , Carrier W. L.
Published: May 2006

Xeroderma pigmentosum (XP) is a recessively transmitted disorder of man characterized by increased sensitivity to ultraviolet light. Homozygous, affected individuals, upon exposure to sunlight, sustain severe damage to the skin; this damage is characteristically followed by multiple basal and squamous cell carcinomas and not uncommonly by other malignant neoplasia. A tissue culture cell line was derived from the skin of a man with XP. Our measurements of ultraviolet-induced pyrimidine dimers in cellular DNA show that normal diploid human skin fibroblasts excise up to 70 per cent of the dimers in 24 hours, but that fibroblasts derived from the individual with XP excise less than 20 per cent in 48 hours. Alkaline gradient sedimentation experiments show that during the 24 hours after irradiation of normal cells a large number of single-strand breaks appear and then disappear. Such changes are not observed in XP cells. XP cells apparently fail to start the excision process because they lack the required function of an ultraviolet-specific endonuclease. These findings, plus earlier ones of Cleaver on the lack of repair replication in XP cells, raise the possibility that unexcised pyrimidine dimers can be implicated in the oncogenicity of ultraviolet radiation.
TRANSPORT CHANGES RAPIDLY INITIATED BY SERUM ADDITION TO “CONTACT INHIBITED” 3T3 CELLS
Authors: Cunningham Dennis D. , Pardee Arthur B.
Published: May 2006

Two- to fourfold increases in uridine and phosphate uptake were brought about within 10 to 15 minutes after adding fresh serum to confluent 3T3 cells. The stimulation of transport was specific, since no serum effect was observed for 3-
O
-methyl-D-glucose or amino acids. The early increase in RNA labeling, previously identified by
14
C-uridine incorporation, could be accounted for by this transport effect. Increased labeling with
32
P-phosphate of at least five phospholipids occurred soon after adding serum. This increase, however, could not be accounted for by increased transport. Both of these results suggest that specific early membrane changes are involved in “contact inhibition.”

The following results are consistent with this suggestion. Uptake of uridine and phosphate by nonconfluent 3T3 cells was higher than by confluent cells and was only slightly increased by fresh serum. In contrast, uptake of these substrates by Polyoma virus-transformed 3T3 cells, which are not subject to “contact inhibition,” was not significantly decreased after the cells became confluent, and serum addition had no effect on transport by either nonconfluent or confluent Polyoma virus-transformed 3T3 cells.

Fractionation of serum on Sephadex G-200 demonstrated that the factor which stimulated phosphate transport was different from the previously identified factor which stimulates DNA synthesis by confluent 3T3 cells.
EVIDENCE FOR A SINGLE-STRANDED ADENOVIRUS-ASSOCIATED VIRUS GENOME: FORMATION OF A DNA DENSITY HYBRID ON RELEASE OF VIRAL DNA
Authors: Rose James A. , Berns Kenneth I. , Hoggan M. David , Koczot Frank J.
Published: May 2006

Extracted adenovirus-associated virus DNA is known to be double-stranded, and, therefore, it has been assumed that these virus particles contain a double-stranded genome. Recent findings, however, have suggested that the DNA in virus particles is equivalent to only half the molecular weight of extracted molecules. A density analysis of DNA extracted from a mixture of virus particles containing either bromodeoxyuridine-substituted or unsubstituted DNA shows that virions contain single-stranded DNA which, when released, forms duplex structures. A similar circumstance is as yet unknown among other viruses.
EFFECT OF THE LAMBDA REPRESSOR ON THE BINDING OF RNA POLYMERASE TO DNA
Authors: Hayward William S. , Green Melvin H.
Published: May 2006

Experiments were designed with the aim of understanding the mechanism whereby the lambda repressor inhibits messenger RNA synthesis. Complexes containing lambda DNA and RNA polymerase were isolated from repressed and derepressed lysogens and analyzed for the relative amounts of RNA polymerase per phage genome. The data indicate that the repressor inhibits the binding of RNA polymerase to promoter sites known to be under direct control of the repressor.
THE COMPOSITION OF FOSSIL OYSTER SHELL PROTEINS
Authors: Matter III Philip , Davidson Franklin D. , Wyckoff Ralph W. G.
Published: May 2006

Analyses of the protein residues recovered from fossil oyster shells of ages from the Pleistocene through the Cretaceous show substantially the same amino acids as are present in modern proteins. The amount of these residues declines sharply to the Oligocene, after which it proceeds more slowly. These older proteins contain relatively less aspartic acid and glycine than do their younger counterparts.
SV40 GENE ACTIVITY DURING LYTIC INFECTION AND IN A SERIES OF SV40 TRANSFORMED MOUSE CELLS
Authors: Martin Malcolm A. , Axelrod David
Published: May 2006

Transcription of SV40 DNA was measured during lytic infection and in five SV40 transformed mouse cell lines. During productive infection, 50 per cent of viral DNA reacted with saturating amounts of lytic RNA. Varying portions of the SV40 genome were transcribed in transformed mouse cells, ranging from 15 per cent in a line which failed to yield virus, to 50 per cent in one line from which high titers of virus were obtained following cell fusion. The RNA from the SV40 transformed cell line, which saturated 50 per cent of the viral DNA, could not be distinguished from SV40 lytic RNA in reciprocal competition-hybridization experiments. These results suggest that some block or defect, subsequent to the transcription of SV40 DNA, prevents the appearance of progeny virus in this transformed 3T3 cell.
AM(1), THE FIRST GENETIC MARKER OF HUMAN IMMUNOGLOBULIN A
Authors: Vyas G. N. , Fudenberg H. H.
Published: May 2006

The genetic markers of human immunoglobulins have significantly contributed to the understanding of the molecular biology of antibody synthesis. Like the Gm markers of IgG, the first genetic marker of serum IgA, a major immunoglubulin of exocrine secretions, has now been defined and termed Am(1). It is inherited as a Mendelian dominant trait and is independent of the Gm and Inv allotypes. Am(1) is localized in the α-chains of the γA
2
subclass and is independent of the serum γA
2
levels. Its polymorphism makes it suitable for studies in population genetics and the molecular biology of IgA globulin.
OXYTOCIN AND NEUROHYPOPHYSEAL PEPTIDES: SPECTRAL ASSIGNMENT AND CONFORMATIONAL ANALYSIS BY 220 MHz NUCLEAR MAGNETIC RESONANCE
Authors: Johnson LeRoy F. , Schwartz I. L. , Walter Roderich
Published: May 2006

Magnetic resonance peaks have been assigned to individual protons of the constituent amino acids in the neurohypophyseal hormone, oxytocin, and in related peptides. The assignments were made possible by operation at 220 MHz with the use of variable temperature studies, proton homonuclear spin-decoupling, and comparison of spectra of oxytocin analogs. Some of the observed chemical shifts, and NH-CH
α
coupling constants were studied in relation to the conformation of the hormone.
PHOSPHORYLATION OF LIVER HISTONE FOLLOWING THE ADMINISTRATION OF GLUCAGON AND INSULIN
Authors: Langan Thomas A.
Published: May 2006

The administration of glucagon to rats causes a marked increase in the phosphorylation of a specific serine residue in lysine-rich (f1) histone of liver during a one-hour period following the administration of the hormone. It is proposed that histone phosphorylation is the mechanism by which glucagon, and perhaps other hormones whose actions are mediated by adenosine 3′,5′-cyclic phosphate (cyclic AMP), induce RNA synthesis in target tissues. The incorporation of
32
P-phosphate into lysine-rich histone is determined by isolation of a tryptic peptide which contains the phosphorylated serine residue. This peptide is identical to the major tryptic phosphopeptide obtained from lysine-rich histone after phosphorylation
in vitro
by a purified cyclic AMP-dependent liver histone kinase preparation; the partial sequence Lys-Ala-SerPO
4
(Thr,Ser,Glu,Pro
2
,Gly,Val,Ile,Leu)Lys has been determined for the peptide. Hydrocortisone and adrenocorticotrophic hormone do not cause a detectable increase in histone phosphorylation in liver. However, insulin, which like glucagon induces an actinomycin sensitive synthesis of liver enzymes, also causes increased histone phosphorylation.
CYCLIC NUCLEOTIDE-DEPENDENT PROTEIN KINASES, IV. WIDESPREAD OCCURRENCE OF ADENOSINE 3′,5′-MONOPHOSPHATE-DEPENDENT PROTEIN KINASE IN VARIOUS TISSUES AND PHYLA OF THE ANIMAL KINGDOM
Authors: Kuo J. F. , Greengard Paul
Published: May 2006

Adenosine 3′,5′-monophosphate-dependent protein kinase activity was found in about thirty sources including many mammalian tissues as well as species representative of eight different invertebrate phyla. The data support a unifying theory for the mechanism of action of adenosine 3′,5′-monophosphate, namely that its many and diverse effects are mediated through activation of tissue-specific protein kinases.
Spin Delocalization in Retinals
Authors: Patel Dinshaw J. , Shulman R. G.
Published: May 2006

A 220-MHz proton nuclear magnetic resonance study of the binding of Ni(II) and Co(II) acetylacetonates to retinyl-
N
-methyl Schiff's bases is presented. The study has yielded the magnitude and sign of spin densities at the carbon atoms in the π system of the 9-
cis
, 13-
cis
, and all
trans
isomers. From a comparison of the experimental results with molecular orbital calculations, a mechanism for transfer of spin from the metal to the retinyl Schiff's base and its subsequent delocalization down the polyene chain is provided.
Brain Function and Macromolecules, VI. Autoradiographic Analysis of the Effect of a Brief Training Experience on the Incorporation of Uridine into Mouse Brain
Authors: Kahan Barry E. , Krigman Martin R. , Wilson John Eric , Glassman Edward
Published: May 2006

In agreement with the data of Beach
et al.
(these
Proceedings
, 62, 692 (1969)) on the effects of avoidance training on protein synthesis, we report autoradiographic evidence for the increased incorporation of radioactive uridine into limbic system structures of the brains of trained mice. There is also a decreased incorporation into the outer layers of the neocortex. The observed responses in labeling are restricted to the nuclei of neurons. The significance of these changes in brain function is not known but they may be related to those processes of the memory consolidation phenomenon affected by inhibitors of protein and RNA synthesis.
Deoxynucleotide-Polymerizing Enzymes of Calf Thymus Gland, IV. Inhibition of Terminal Deoxynucleotidyl Transferase by Metal Ligands
Authors: Chang L. M. S. , Bollum F. J.
Published: May 2006

The polymerization of deoxynucleoside triphosphates, catalyzed by terminal deoxynucleotidyl transferase from calf thymus gland, is strongly inhibited by various metal chelators. The reaction appears to be first order with respect to enzyme, deoxynucleoside triphosphate, and initiator, indicating that there is only one catalytic center for each enzyme molecule. The presence of metal chelator does not affect the molecular state of the enzyme or the order of reaction. An analysis of the kinetics of
o
-phenanthroline inhibition demonstrates that the ligand is noncompetitive with nucleoside triphosphate substrate and strictly competitive with oligodeoxynucleotide initiator. These results, obtained in the presence of millimolar Mg
++
, suggest that the initiator binds to the enzyme through a transition metal atom and ligand inhibition occurs at that site. The precise spatial arrangement of the coordination orbitals around a metal atom provides a model to visualize the specificity of the enzyme for the 3′-OH end of the growing polynucleotide chain.