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Two different methods for shallow junction formation and poly-Si doping based on outdiffusion of As, B, BF 2 from CoSi 2 have been evaluated in complete sub 0.5μm NMOS and PMOS processes. p + and n + junctions were processed with a total depth down to 100nm and 140nm, respectively. The leakage current density was measured in the range of 1E-9 Acm −2 at V R =-5V for p + diodes. The n + diodes exhibit an increased leakage current at 1E-5 Acm −2 . In order to evaluate the device performance, transistors with effective channel lengths down to 0.25μm and good static device behavior have been fabricated by means of X-ray lithography. A special outdiffusion technique is able to reduce the boron penetration through thin gate oxides ≥5nm.

The retinoblastoma gene product (Rb), a cellular growth suppressor, complexes with viral and cellular proteins that contain a specific binding domain incorporating three invariant residues: Leu-X-Cys-X-Glu, where X denotes a nonconserved residue. Hydrophobic and electrostatic properties are strongly conserved in this segment even though the nonconserved amino acids vary considerably from one Rb-binding protein to another. In this report, we present a diagnostic computer pattern for a high-affinity Rb-binding domain featuring the three conserved residues as well as the conserved physico-chemical properties. Although the pattern encompasses only 10 residues (with only 4 of these explicitly defined), it exhibits 100% sensitivity and 99.95% specificity in database searches. This implies that a certain pattern of structural and physico-chemical properties encoded by this short sequence is sufficient to govern specific Rb binding. We also present evidence that the secondary structural conformation through this region is important for effective Rb binding.

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions., 13 pages, 7 pictures

The research on teacher leadership like that of school reform has become more and more nuanced in the last two decades as the reform context has changed (Smylie, 1997; York-Barr & Duke, 2004). Since the 1980s there have been consistent calls for teachers to be leaders, often with no preparation, support, or understanding of the school culture nor the demands of the reform context.

The SO2 emission from six fluidized bed combustors was examined. Approximately 71.5% of the fuel sulphur was found to be emitted as SO2 in sorbent-free tests. General observations on the effects of Ca/S molar ratio, limestone size and recycle systems are presented. The effects of limestone type and superficial velocity were found to be insignificant, as was the effect of bed temperature in the range 800-950°C. In tests with fine solid and liquid fuels, circulating FBC's were found to provide significantly better sulphur capture than bubbling FBC's. On a etudie l'emission de SO2 de six combusteurs a lit fluidise. On a constate qu'environ 71,5 % du soufre du combustible etait emis sous forme de SO2 dans les essais realises en l'absence de sorbants. Des observations generales sont presentees sur les effets du rapport molaire Ca/S, de la taille des particules calcaires et des systemes de recyclage. Les effets du type de calcaire et de la vitesse superficielle sont apparus negligeables, tout comme l'effet de la temperature dans la gamme 800-950°C. Dans les tests realises avec des combustibles solides fins et liquides, on a pu demontrer que les combusteurs a lits fluidises circulants permettent une meilleure production de soufre que les systemes en lits fluidises a bulles.

Minority carrier mobility has been extracted from measurements on NMOS transistors with effective channel lengths down to 0.35 ?m within the temperature range 208-403 K. The results indicate a significant mobility reduction for short channel devices at temperatures below 300 K. Furthermore, a slight increase of the threshold voltage was observed in the short channel region. Both effects can be explained by an inhomogeneous lateral doping profile within the channel, which was confirmed with 2-dimensional device simulation.

A series of 5,5-disubstituted hydantoin derivatives was synthesized by alkylating 5,5-bis(mercaptomethyl)-2,4-imidazolidinedione (3) with various halomethylaromatic or halomethylheteroaromatic precursors, or by using the Buchener-Berg procedure on the required ketone. When evaluated for their ability to inhibit HIV-induced cell killing and virus production in CEM or MT-2 cells only compounds 2, 4n, 4o, and 4i demonstrated modest activity, the latter with an IC50 = 53 microM.

Sub-0.5 mu m CMOS devices have been successfully fabricated by means of X-ray lithography at all levels. The overlay of subsequent lithography levels was determined to be

The secondary structure for two murine recombinant proteins, interleukins 1 alpha and 1 beta (rmIL-1 alpha and -1 beta), has been analyzed by Fourier transform infrared (IR) spectroscopy and then compared to results obtained by X-ray diffraction, circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy. The IR results obtained here for rmIL-1 alpha and -1 beta suggested that their secondary structures consisted predominantly of beta-sheets or strands. However, the analysis also revealed a significant absorption band near 1656 cm-1, which is typically assigned to alpha-helical or random structures. When these same murine polypeptides were analyzed by CD, no evidence of alpha-helical structures was observed. Further, published X-ray diffraction and NMR studies characterizing the human forms of IL-1 alpha and -1 beta indicate the absence of alpha-helices and that the human proteins are composed mainly of beta-strands (i.e., greater than 55%), with approximately 24% of the amino acids involved in large loops connecting the strands. The murine IL-1 proteins, when compared to their respective human counterparts, each show greater than 80% sequence homology. Given this fact, the CD analyses, and the result that this IR band amounted to 21% of the overall integrated area, the absorption peak at 1656 cm-1 was attributed to the presence of large loops rather than to alpha-helical or random structures. Such a structural assignment appears reasonable and is totally consistent with the established existence of large loops in the human forms as well as in other proteins found to fold similarly (viz., human bFGF).(ABSTRACT TRUNCATED AT 250 WORDS)

Flow Cytometry (FC) is a popular method for the simultaneous quantitation of multiple specific proteins and other molecules in each cell of a single cell suspension (1). Laser Scanning Cytometry (LSC) is a closely related technology that provides many of the benefits of FC and offers additional features that allow morphological and biochemical analysis of a cell population (2,3). In both methods, quantitation of endogenous cellular proteins generally requires antibodies against the protein of interest. These antibodies must be either directly labeled with a fluorochrome or detected by a fluorescently-labeled secondary antibody. Using fluorescently-labeled antibodies in combination with fluorescent dyes that quantitatively bind to DNA, both FC and LSC have been valuable in measuring the quantities of specific proteins in relation to cell cycle position (4). In contrast to FC, where a single cell suspension is passed through a fixed-position laser beam, LSC analyzes cells fixed to a surface such as a microscope slide or cover slip. Since the position of the cell on the slide is part of the recorded data, it is possible to visualize the cell after the initial recording event or to subsequently stain the cell with another fluorescent probe and make a second measurement. LSC also allows analysis of cells following biochemical treatments that are incompatible with analysis by FC. In this chapter we describe the value of LSC in analyzing chromatin-associated proteins. Specifically, we describe an in situ fractionation procedure that allows measurement of total and chromatin-associated MCM2, a DNA helicase subunit, as a function of cell cycle position.

Quaternion algebra provides a strong base for the representation of orientations and rotations of objects in three dimensions. Compared to Euler angles they are simpler to compose, numerically more stable, more efficient and avoid the problem of gimbal lock. This paper addresses the instruments tracking of medical navigation by using rotation matrices and quaternion. The calculation of the instrument’s tip of the video-optical localizer for the complete spatial plane plays a decisive role.

Quantitation of specific proteins in complex mixtures is simplified by the use of antibodies directed against the protein of interest. If the specific protein is differentially expressed within a population of cells, quantitation of the protein in cell lysates by immunoblotting will provide an average quantity of the protein per cell. As a result, when lysates of different cell populations are compared, large changes in the amount of a protein in a small percentage of cells cannot be distinguished from small changes in the amount of a protein in a large percentage of cells. Flow cytometric analysis solves this problem by providing a means to measure the amount of a specific protein within each individual cell in a population. A fluorescently labeled probe, usually an antibody, is required for detection of the protein. A single cell suspension is reacted with an antibody and passed through a flow cytometer, which focuses the cell suspension into a stream that intersects a laser beam. As each cell passes through the beam, the fluorescent probe in each cell is excited and photomultiplier tubes register the degree of fluorescence (1). Multivariate analysis, the simultaneous measurement of multiple parameters, is a powerful feature of flow cytometry. When determining the quantity of a specific protein in a cell, the quantity of other molecules in the same cell can also be measured by using additional fluors specifically targeted to other molecules. Examples of second molecules measured simultaneously include DNA (2–4) or additional proteins (5). In addition, measurement of light scatter can provide information about cell size and granularity. Most flow cytometers are capable of measuring six colors plus light scatter, but specialized flow cytometers that are capable of measuring as many as eighteen colors are now available.

In order to determine the influence of X-ray induced radiation damages, surface channel PMOS devices with partially scaled 0.5 μ m design rules were fabricated using optical and X-ray lithography. With a gate oxide thickness d ox = 10 nm the X-ray processed transistors show a threshold voltage shift δV T = -10 mV, whereas transistors with d ox = 20 nm show a V T shift of δV T = -40 mV relativ to optically processed devices. The degradation under hot carrier injection in terms of deviations of δg m , δV T , δI D and δS is almost identical for both types of transistors and is in the order of 4%.

The discrete IGBT (Insulated Gate Bipolar Transistor) is the most important power semiconductor device for power conversion and control in the medium power range with voltages >400 V. Next generation IGBTs require low thermal budget p-n junction formation for the back side field stop and emitter layer. The requirement for the limited thermal budget is due to the fact that the front side metallization does not allow high temperature treatment for the activation of the field stop layer. Therefore, laser annealing experiments have been carried out using a frequency doubled Yb:YAG laser at a wavelength of 515 nm with an energy density up to 4 J/cm2. In order to find out appropriate process conditions for a single step Boron and Phosphorous laser annealing process, parameters for ion implantation as well as energy density and pulse duration of the laser have been varied. The doping profiles of Boron and Phosphorous were measured by Secondary Ion Mass Spectroscopy (SIMS) and Spreading Resistance Probe (SRP) in order to assess the dopant activation behaviour. The main interest was the activation of the Phosphorous doped field stop layer in a depth range of 1 mum. A strong dependency of Phosphorous activation on implanted Boron dose was observed with dopant activation up to 70%.

We propose thin single-layer grating waveguide structures to be used as high-reflectivity, but low thermal noise, alternative to conventional coatings for gravitational wave detector test mass mirrors. Grating waveguide (GWG) coatings can show a reflectivity of up to 100% with an overall thickness of less than a wavelength. We theoretically investigate GWG coatings for 1064nm based on tantala (Ta2O5) on a Silica substrate focussing on broad spectral response and low thickness.

In this paper, carbon nanotubes/nanofibers for microwave amplifiers and parallel e-beam lithography have been discussed. Field emission properties of CN arrays will be presented.

Lytic infection of African green monkey kidney (CV-1) cells by simian virus 40 (SV40) is characterized by stimulation of DNA synthesis leading to bypass of mitosis and replication of cellular and viral DNA beyond a 4C DNA content. To define mechanisms underlying the absence of mitosis, the expression levels of upstream regulatory molecules of mitosis-promoting factor (MPF) were compared in parallel synchronized cultures of SV40-infected and uninfected CV-1 cells. The DNA replication/damage checkpoint kinase Chk1 was phosphorylated in both uninfected and SV40-infected cultures arrested at G 1 /S by mimosine, consistent with checkpoint activation. Following release of uninfected cultures from G 1 /S, Chk1 phosphorylation was lost even though Chk1 protein levels were retained. In contrast, G 1 /S-released SV40-infected cultures exhibited dephosphorylation of Chk1 in S phase, followed by an increase in Chk1 phosphorylation coinciding with entry of infected cells into >G 2 . Inhibitors of Chk1, UCN-01 and caffeine, induced mitosis and abnormal nuclear condensation and increased the protein kinase activity of MPF in SV40-infected CV-1 cells. These results demonstrate that SV40 lytic infection triggers components of a DNA damage checkpoint pathway. In addition, chemical inhibition of Chk1 activity suggests that Chk1 contributes to the absence of mitosis during SV40 lytic infection.

Livers from wild-type and p53-deficient mice were analyzed for the expression of cell-cycle regulatory proteins in an attempt to determine the mechanism for the increased proliferation of liver cells in p53-deficient miceassociated with enhanced susceptibility to aflatoxin-induced liver cancer. The most striking difference found was a significant reduction of the cyclin-dependent kinase inhibitor p27 k i p 1 in the livers of 3-mo-old p53-/- mice, whereas only small changes were found in the expression of cyclins, cyclin-dependent kinases, and the inhibitors p21 c i p 1 and p16 i n k 4 a . Relative to wild-type liver, the amounts of p27 k i p 1 mRNA were reduced at both 1 and 3 mo, whereas the levels of p27 k i p 1 protein were decreased only at 3 mo. These results identify an uncharacterized link between the expression of p53 and p27 k i p 1 that may involve both transcriptional and post-transcriptional regulation and allow hepatocytes to continue to proliferate after 3 wk of age. We postulate that this increased proliferation leads to increased susceptibility to aflatoxin-induced hepatocarcinogenesis.

For short-haul applications, the authors present a two-chip receiver, which consists of a high-gain preamp and a high-sensitivity clock and data recovery-demultiplexer (CDR-DMUX). If the high-gain preamp is integrated into the metal can of the PIN-diode (resulting in a PIN-preamp) the space saving due to this 'autoshielding' is significant. The gain bandwidth product of the amplifier is restricted by the coupling inside the metal can. The sensitivity of the CDR-DMCTX is possibly dependent on second-order effects like coupling to outputs (direct or via common mode).

We propose a novel type of earthbound gravitational wave detector targeting a frequency band of 0.1–10 Hz. By using repeatedly free falling test masses—juggling—one can in principle decouple test masses from the seismically noisy environment and avoid suspension thermal noise in a straightforward manner. As a consequence, the measurement process will not be continuous anymore. We show that to a given extent, continuous signals can be extracted from the discontinuous data by removing a linear trend for the data as well as for the filter templates in each measurement cycle. Moreover, using a laser interferometer topology in principle allows for scaling to a long-baseline detector to achieve scientifically significant strain sensitivities and to be complementary to advanced detectors that are optimized for a frequency band of 10–104 Hz. The presented Michelson type juggled interferometer offers a variety of interesting technical as well as theoretical challenges during the development to an instrument for new astronomy.

The infection of permissive monkey kidney cells (CV-1) with simian virus 40 induces G1 growth-arrested cells into the cell cycle. After completion of the first S phase and movement into G2, mitosis was blocked and the cells entered another DNA synthesis cycle (second S phase). Growth-arrested CV-1 cells replicated significant amounts of viral DNA in the G2 phase with the majority of synthesis occurring during the second S phase. When mimosine-blocked (G1/S) infected cells were released into the cell cycle, a major portion of the viral DNA was detected in G2 with the largest accumulation in the second S phase. The total DNA produced per infected cell was 10–12 C with approximately 0.5–2 C of viral DNA replicated per cell. Therefore the majority of the DNA per cell was cellular, 4 C from the first S phase and approximately 4–6 C from the second cellular synthesis phase.

Ethambutol is an established front-line agent for the treatment of tuberculosis, and is also active against Mycobacterium avium infection. However, this agent exhibits toxicity, and is considered to have low potency. The action of ethambutol on the mycobacterial cell wall, particularly the arabinan, and comparison of the structure of ethambutol with several of the cell-wall saccharides, suggested that ethambutol–saccharide hybrids might lead to agents with a more selective mechanism of action. To this end, eight ethambutol–saccharide hybrids were synthesized and screened against M . tuberculosis and several clinical isolates of M . avium .

During a survey for tuberculosis in wild carnivores and omnivores, Mycobacterium bovis was cultured from pooled lymph nodes of three adult female coyotes (Canis latrans) harvested by hunters in Michigan (USA). No gross or histologic lesions suggestive of tuberculosis were seen in these animals. One coyote was taken from Montmorency county and two coyotes from Alcona county located in the north-eastern portion of Michigan's Lower Peninsula where free-ranging white-tailed deer (Odocoileus virginianus) have been found infected with bovine tuberculosis. It is thought that these coyotes became infected with M. bovis through the consumption of tuberculous deer. Other species included in the survey were the opossum (Didelphis virginiana), raccoon (Procyon lotor), red fox (Vulpes vulpes), bobcat (Felis rufus), and badger (Taxidea taxus).

Simian virus 40 (SV40) infection of quiescent monkey kidney cells stimulates two successive rounds of cellular DNA synthesis without an intervening mitosis. This uncoupling of S phase and mitosis indicates that SV40 modulates pathways regulating the G2-to-M phase transition. To examine the integrity of mitotic initiation pathways in infected cells that have bypassed mitosis, SV40-infected CV-1 cells were treated with okadaic acid (OA), a known inducer of premature mitosis in other cell types. OA treatment triggered the appearance of the mitotic marker MPM-2 in SV40-infected CV-1 cells progressing through either the first (diploid) or second (tetraploid) S phases. These results demonstrate that a subset of mitotic pathways are intact but inactive in SV40-infected cells that have bypassed mitosis and initiated tetraploid S phase.

Conformal epitaxy is an epitaxial growth technique capable of yielding low dislocation density III-V films on Silicon. In this technique, the growth of the III-V material occurs parallel to the silicon substrate, from the edge of a previously deposited III-V seed, the vertical growth being stopped by an overhanging capping layer. As an example, conformal GaAs layers on Silicon, presenting dislocation densities below 105cm−2, have been obtained using selective vapor phase epitaxy. These layers have then been used as high quality GaAs on Si substrates for subsequent vertical MBE regrowth of active structures. In this paper, we report on the integration of surface-emitting microcavity LEDs with their silicon drivers using this conformal growth technique. The global technology concept and the design of the active structures are first presented. The compatibility of the conformal growth technique with CMOS technology is then checked: the impact of the integration process on the performances of the drivers is for example quantified. Characterisations of the high crystalline quality of the conformal layers and of the LEDs structures grown on it are then shown. The electro-optical characteristics of the LEDs on Si are finally compared to those of reference LEDs on GaAs substrates in order to prove the efficiency of the integration procedure.

Sponge-like Si nanostructures embedded in SiO2 were fabricated by spinodal decomposition of sputter-deposited silicon-rich oxide with a stoichiometry close to that of silicon monoxide. After thermal treatment a mean feature size of about 3 nm was found in the phase-separated structure. The structure of the Si-SiO2 nanocomposite was investigated by energy-filtered transmission electron microscopy (EFTEM), EFTEM tomography, and atom probe tomography, which revealed a percolated Si morphology. It was shown that the percolation of the Si network in 3D can also be proven on the basis of 2D EFTEM images by comparison with 3D kinetic Monte Carlo simulations.

The cause of tooth movement with a multiband or multibracket appliance is the force system in the bracket, which is generated by an archwire and transmitted by a bracket to the respective tooth. Continuous arch wires are, from the biomechanical point of view, a statically multiply undetermined system. Quantitative determination of the forces and torques acting at the individual teeth, and thus observance of a non-critical level of applied forces, is therefore extremely problematic in practice, the force is applied by the orthodontist more or less "intuitively" on the basis of recommendations evolved in theory and in vitro. The measuring technique presented in this paper is designed to permit these force systems to be recorded in vivo for the first time, allowing account to be taken of the individual situation "tooth-periodontium-bone". Evolvement of an appropriate measuring principle was followed by development of the individual components of the measuring system. The results of the subsequent initial in vitro test series offer the prospect of successful clinical application.

Designing new drugs that inhibit the biosynthesis of the D-arabinan moiety of the mycobacterial cell wall arabinogalactan is one important basic approach for treatment of mycobacterial diseases. However, the biosynthetic origin of the D-arabinosyl monosaccharide residues themselves is not known. To obtain information on this issue, mycobacteria growing in culture were fed glucose labeled with 14C or 3H in specific positions. The resulting radiolabeled cell walls were isolated and hydrolyzed, the arabinose and galactose were separated by high-pressure liquid chromatography, and the radioactivity in each sugar was determined. [U-14C]glucose, [6-3H]glucose, [6-14C]glucose, and [1-14C]glucose were all converted to cell wall arabinosyl residues with equal retention of radioactivity. The positions of the labeled atoms in the arabinose made from [1-14C]glucose and [6-3H]glucose were shown to be C-1 and H-5, respectively. These results demonstrated that the arabinose carbon skeleton is formed via the nonoxidative pentose shunt and not via hexose decarboxylation or via triose condensations. Since the pentose shunt product, ribulose-5-phosphate, is converted to arabinose-5-phosphate as the first step in 3-keto-D-manno-octulosonic acid biosynthesis by gram-negative bacteria, such a conversion was then searched for in mycobacteria. However, cell-free enzymatic analysis using both phosphorous nuclear magnetic resonance spectrometry and colorimetric methods failed to detect the conversion. Thus, the conversion of the pentose shunt intermediates to the D-arabino stereochemistry is not via the expected isomerase but rather must occur via novel metabolic transformations.

The changes in cell size and total protein were determined for G1-arrested, contact-inhibited CV-1 cells infected with Simian virus 40 (SV40). The assays used were the Biorad total protein assays (Bradford and DC protein assays) on a standard number of cells, total protein as assayed by fluorescein isothiocyanate (FITC) and SR101 by flow cytometry, orthoganol (90°) light scatter by flow cytometry, and direct microscopic measurement with an ocular micrometer. Uninfected CV-1 cells and two cell lines with variations in DNA content (diploid vs. tetraploid) were used as controls for the studies presented. The results demonstrated a 40–60% increase in total protein at 32 to 42 h postinfection. These increases were similar to values obtained as control cells progress through the cell cycle. At later times postinfection (>42 h), total protein decreased due to cellular changes resulting from viral replication and cell death.

Previous experiments with the simian virus 40 mutant tsA357R-K (tsA30) demonstrated a T-antigen function that is required for production of cells with a greater-than-G2-phase DNA content. In this study, temperature shift experiments indicated that the temperature-sensitive function of tsA357R-K, which is necessary for entry into the greater-than-G2 phase, is not required in G1 or S but must be supplied in the G2 phase.

Simian virus 40 (SV40) infection of monkey kidney cells induces successive rounds of cellular DNA synthesis without intervening mitosis. To gain an understanding of the mechanisms responsible for disruption of cell cycle control during lytic infection, pRB phosphorylation and cell cycle distribution were examined following SV40 infection of CV-1 cells. The hypophosphorylated pRB present in confluent CV-1 cells was phosphorylated within 14 h following SV40 infection. Phosphorylated pRB then remained the predominant form as cells progressed from late G1 through S phase. Hypophosphorylated pRB reappeared as cells moved through G2 and acquired a tetraploid (G2) DNA content. The reappearance of hypophosphorylated pRB in a population with decreasing numbers of cells in G1 phase and increasing numbers of cells inG2 suggests that accumulation of hypophosphorylated pRB may be involved in T antigen-induced tetraploidy.

These studies examined cell cycle progression and quantitative changes in T-antigen following infection by SV40. Single cells were assayed by multiparameter flow cytometric analysis (FCM) for DNA content and T-antigen expression. Conditions were used which permitted permissive, semi-permissive, and non-permissive cells to be monitored through two rounds of DNA synthesis induced by SV40. The permissive cells included the monkey kidney cell lines; CV-1, Vero and BSC-1 and the COS-1 and COS-7 which are CV-1 cells transformed with an origin defective SV40. The non-permissive cell strains included mouse embryo fibroblasts, Chinese hamster fibroblasts, and IMR-90, a human diploid fibroblast. Cell types differed in the maximal amount of T-antigen expressed per cell. Additionally, all cell types expressed a limited quantity of T-antigen for each cell cycle phase and the quantity increased in each successive phase. The level in each phase was increased only two-fold when 100 times more virus was used. Thus, for an infected population the quantity of T-antigen was dependent on cell cycle distribution. High levels of T-antigen were not required for permissive infection; however, permissive cells were distinguished from non-permissive cells by the G2 levels. Permissive G2 cells had more than double the T-antigen content expressed in G1, while nonpermissive G2 cells had less than a two-fold increase over G1 levels. The appearance of cells with tetraploid DNA content and the failure to undergo mitosis correlated to the higher T-antigen levels in the G2 of the permissive cells. Two other strains of SV40, 776, and VA45 exhibit similar values for T-antigen expression and movement into tetraploid DNA content. This study establishes the levels of T-antigen correlated to the cell cycle and cell type.

L-DOPA had no effect on the endogenous phosphorylation of proteins after extraction with 1% Triton X-100 from hamster melanoma. When proteins were purified further by wheat germ-agglutinin chromatography, however, a dramatic and dose-dependent inhibitory effect of DOPA on glycoprotein phosphorylation was observed in the presence of Mn +2.

Infection of quiescent CV-1 cells with simian virus 40 mutant tsA30 at 37 degrees C resulted in the induction of two rounds of cellular DNA synthesis in T-antigen-positive cells, as previously described for wild-type simian virus 40. Following infection with tsA30 at 40.5 degrees C, T-antigen-positive cells were induced into S phase and reached a diploid G2 DNA content; however, a second S phase was not initiated. The failure of tsA30-infected CV-1 cells to enter tetraploid S phase at 40.5 degrees C identifies a T-antigen function, distinct from T-antigen functions responsible for stimulation of cell DNA synthesis, which is required for initiation of a second round of DNA synthesis without mitosis.