Herpes simplex virus type 1 ribonucleotide reductase large subunit: regions of the protein essential for subunit interaction and dimerization

We have constructed a series of random N-terminal deletions of the large subunit (R1) of the herpes simplex virus type 1 ribonucleotide reductase. Deletions extended throughout the R1 gene open reading frame and, in total, 31 different truncated polypeptides were expressed in Escherichia coli using the T7 expression system. N-Terminal truncations were analyzed for their interaction with the small subunit (R2) of ribonucleotide reductase using a sensitive enzyme-linked immunosorbent assay (ELISA) method and for their ability to complement R2 in ribonucleotide reductase assays. Truncated proteins were also tested for homodimerization using gel-filtration chromatography. The results identified a region of R1 between amino acids 349 and 373 which was essential for subunit interaction. Proteins lacking up to 348 amino-terminal residues associated with R2 and complemented R2 in ribonucleotide reductase assays. Proteins commencing at amino acid 373 and beyond did not interact with R2 and were inactive in enzyme assays. Using a plasmid which expressed an N-terminal deleted protein commencing at amino acid 247, we constructed two defined C-terminal deletions to give proteins comprising amino acids 247-434 and 247-996 of R1. Neither of these truncated proteins bound R2 and we concluded that a second region between amino acids 996 and 1137 (the C-terminus) is required for interaction with R2. Gel-filtration studies indicated that deletion of the first 420 amino acids from R1 did not affect dimerization. However, deletions of 457 amino acids and larger gave proteins which existed as monomers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mice lacking serum paraoxonase are susceptible to organophosphate toxicity and atherosclerosis

Serum paraoxonase (PON1) is an esterase that is associated with high-density lipoproteins (HDLs) in the plasma; it is involved in the detoxification of organophosphate insecticides such as parathion and chlorpyrifos. PON1 may also confer protection against coronary artery disease by destroying pro-inflammatory oxidized lipids present in oxidized low-density lipoproteins (LDLs). To study the role of PON1 in vivo, we created PON1-knockout mice by gene targeting. Compared with their wild-type littermates, PON1-deficient mice were extremely sensitive to the toxic effects of chlorpyrifos oxon, the activated form of chlorpyrifos, and were more sensitive to chlorpyrifos itself. HDLs isolated from PON1-deficient mice were unable to prevent LDL oxidation in a co-cultured cell model of the artery wall, and both HDLs and LDLs isolated from PON1-knockout mice were more susceptible to oxidation by co-cultured cells than the lipoproteins from wild-type littermates. When fed on a high-fat, high-cholesterol diet, PON1-null mice were more susceptible to atherosclerosis than their wild-type littermates.     

Phase changes in mineral matter of North Dakota lignites caused by heating to 1200 °C

Changes in structures of minerals taking place in lignitic coals during combustion were investigated by first concentrating the mineral matter in the coal by low-temperature ashing and then heating the mineral matter at 100 °C intervals from 200 °C–1200 °C and analysing the major mineral phases by X-ray powder diffraction. Samples of high and low sodium contents were analysed to determine differences in mineral phases with varying sodium contents. Quartz and bassanite were identified as major phases in the low-temperature mineral matter of all ten lignite samples, and pyrite and calcite were identified in eight of the ten samples. Kaolinite was the only clay mineral identified and appeared in nine of the ten samples. Those samples with a sodium oxide content of 8.56 wt % or greater, showed sodium nitrate as a major mineral phase in the low-temperature mineral matter. When the mineral matter was heated to higher temperatures, quartz was a major phase at 1200 °C in five of the samples, and was stable to 1000 °C in all of the samples. Anhydrite was a major mineral phase in all samples from 600 °C–800 °C, appearing in some of the samples as low as 200 °C, and persisting to 1100 °C in some samples. Hematite was found to be a major phase in seven of the ten samples, having an overall temperature range from 300 °C–1000 °C. Magnetite was detected in the range from 800 °C–1200 °C with hercynite forming as a major mineral phase, after magnetite, in two of the samples at 1200 °C. The solid solution series gehlenite-akermanite was found in all ten samples from 1100 °C–1200 °C although they appeared in some samples at 900 °C. Samples of high sodium content formed sodium sulphates at intermediate temperatures and sodium silicates at higher temperatures. Low Sodium samples formed bredigite, a calcium silicate, at higher temperatures.     

A Qualitative Examination of Black College Women's Beliefs About Abuse in Relationships.

Do you wonder how young Black women view violence in dating relationships? In this qualitative study, the authors analyzed the responses of 64 Black college women to open-ended survey questions about abusive relationships. Participants shared their definitions of abuse, beliefs about what causes abuse, experiences of abuse, and opinions about offenders. The results revealed risk factors and sources of support for participants, which can be used to inform practitioners' interventions and prevention strategies. Practical implications for practitioners, future directions for research, and limitations of the study are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface chemical activation of quartz crystal microbalance gold electrodes — analysis by frequency changes, contact angle measurements and grazing angle FTIR

A hydroxyalkanethiol, HS(CH₂)₁₂OH was deposited onto the gold electrodes of quartz crystal microbalances and gold-coated quartz microscope slides in order to aid in subsequent immobilization of antibodies. FTIR and contact angle measurements confirm the presence of thiol on the fresh gold substrates. In contrast, the change in frequency of the quartz crystal during thiol adsorption indicates an apparent decrease in mass rather than the expected increase due to thiol coverage of the surface. This anomalous behavior appears to be partly due to the removal of organic contaminants from the “aged” gold surface by solvent action. In addition, there may be some dissolution of gold by the thiol solution. QCM frequency changes and FTIR have also been used to monitor subsequent carbodiimide activation of the thiol, as well as antibody binding to the activated surface. The thiolated gold surface was used to fabricate an ordered layer of IgG molecules for probing various immuno-reactions. This was demonstrated by the binding of anti-IgG to IgG in the ratio of ca. 1:1.     

谷氨酸酰合成酶(GS)基因扩增选择系统的建立

利用TR－PCR方法从CHOdhfr－细胞中克隆到五株GS基因。对三株GS基因进行了功能分析和序列分析。结果表明，895位核苷酸全部由G变为C，相应的氨基酸白Gly变为Arg，此处变异是CHOdhfr－细胞本身所固有的，不影响GS基因的功能。而399位核苷酸G到A的变异，直接影响到GS基因的功能。用只有895位核苷酸变异的GS基因作扩增选择基因构建表达CAT基因的质粒，转化细胞后，GS基因不仅自身具有扩增的能力，而且能够带动外源基因进行扩增。细胞内外源基因CAT拷贝数可达1000—2000拷贝／细胞，较已有报导的GS基因具有更高的扩增效率，基因扩增前后CAT基因的表达产量提高了10—20倍左右。     

Relating Molecular Structure to Tribological Chemistry: Borate Esters on Copper

The surface and tribological chemistry of 2-propanol and borate esters, isopropoxy tetramethyl dioxaborolane (ITDB), and tetramethyl dioxaborolane (TDB) as gas-phase lubricants for copper surfaces are compared by measuring the friction coefficient and contact resistance in an ultrahigh vacuum tribometer. 2-propanol reacts on copper below room temperature to desorb primarily acetone and causes no friction reduction when used as a gas-phase lubricant. TDB decomposes to deposit BO_x species on the surface and produces an initial decrease in friction coefficient that is not sustained. ITDB, which reacts at room temperature to form a tetramethyl dioxaborolide species on the surface, results in an immediate and sustained decrease in friction coefficient when used as a gas-phase lubricant for copper. This indicates that the surface chemistry of the borate esters can be correlated with their tribological properties and illustrates the effect of replacing a hydrogen atom in TDB with a 2-propoxy group in ITDB on both the surface and tribological chemistry. Analysis of the species formed in the wear track after lubrication with ITDB reveals the presence of graphitic or diamond-like carbon and oxygen, and these elements are also found in the subsurface region of the sample. Rubbing the sample in vacuo after reacting with ITDB shows the removal of a boundary film where the coefficient remains constant and the subsequent removal of the subsurface layer in which the contact resistance rises to its original value.     

Ethnic group preferences for counselor characteristics.

A questionnaire using a paired-comparison procedure to measure preferences for 14 counselor characteristics was administered to 500 students in introductory psychology and business classes at two state universities on the West Coast. A total of 339 usable responses were received from 118 Asian-American students, 64 Mexican-American students, and 157 Caucasian-American students. Rank order preferences for counselor characteristics were almost identical across the three ethnic groups. Preferences for a counselor who had similar attitudes, similar personality, and more education, and was older than the respondent ranked among the top four counselor characteristics for all ethnic groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A survey of dairy cattle worm control practices in southeast Brazil

A survey on the nematode control strategies utilized by dairy farmers in Southeastern Brazil, a region accounting for 46.4% of the national milk production, was conducted through interviews with farmers. To select the producers to be interviewed the region was split into 16 non-contiguous clusters, according to the level of milk production. A systematic sample was then selected in each of the clusters. The interview questionnaire consisted of one-way, multiple-choice and open-ended questions. Data collected were represented by numbers and digitized on a data base (Epi Info, version 5.01b) and analyzed. Out of the 89 farmers interviewed, 37.5% deworm their herd after clinical signs and 62.5% preventively. Generally, anthelmintics are applied from one to 12 times a year (average of 3.79 times a year) in all age categories of animals. Of the anthelmintics used in the last deworming, imidazothiazole was used exclusively by 17.1% of the farmers, benzimidazole by 9.8% and avermectin by 18.3%, while 55.8% used more than one anthelmintic class to deworm their animals. To choose the dosage, most farmers consult the product label (94.8%) and determine the volume to be applied, based on an estimate of the average body weight of each animal (62.9%). Improvements in the general appearance of the herd and weight gains of growing animals were observed by most farmers after deworming (87.3%). However, most of them (66.2%) recalled interrupting the use of some compound in the last few years, due to the detection of no improvement following treatment (32.7%), rising costs of the medication (28.6%), adverse reaction (8.2%), product not available at the time of purchase (4.1%) and decision to change the compound in use (10.2%). Most farmers (95.3%) intend to continue using the same control measures in the following year. Veterinarians play an important role in the farmer's choice to deworm their animals, as many seek advice from them. Therefore, programs aimed at technology transfer should include continuous updates on the subject, especially for veterinarians.