An association between long alleles of a variable number tandem repeat (VNTR) polymorphism in the dopamine receptor D4 gene and the extraversion related personality traits Excitement and Novelty ...Seeking has been reported in healthy subjects. In an attempt to replicate the previous findings, 256 healthy Caucasian volunteers were analysed for a potential relationship between the dopamine receptor D4 exon III VNTR polymorphism and Extraversion as assessed by the Revised Neo Personality Inventory (NEO PI-R). The present study did not yield evidence for an association between Extraversion and the dopamine receptor D4 polymorphism.
We have previously reported the identification and partial characterization of a gene encoding a phospholipase D activity (PLD1) in the yeast, Saccharomyces cerevisiae. Here we report the existence ...of a second phospholipase D activity, designated PLD2, in yeast cells bearing disruption at the PLD1 locus. PLD2 is a Ca2+-dependent enzyme which preferentially utilizes phosphatidylethanolamine over phosphatidylcholine as a substrate. In contrast to PLD1, the activity of PLD2 is insensitive to phosphatidylinositol 4,5-bisphosphate, and the enzyme is incapable of catalyzing the transphosphatidylation reaction with short chain alcohols as acceptors. Subcellular fractionation shows that PLD2 localizes mainly to the cytosol, but could also be detected in the particulate fraction. Thus, the biochemical properties of PLD2 appear to be substantially different from those of PLD1. PLD2 activity is significantly and transiently elevated upon exit of wild type yeast cells from stationary phase, suggesting that it may play a role in the initiation of mitotic cell division in yeast. In view of the significantly different properties of PLD1 and PLD2 and because the yeast genome contains PLD1 as the sole member of the recently defined PLD gene family, it may be concluded that PLD2 is structurally unrelated to PLD1. Thus, the novel PLD2 activity described herein is likely to represent the first identified member of a new PLD gene family.
This paper reports on South African teachers' perceptions of the educational value of new topics in a revised physical sciences high school curriculum, their content knowledge competency of these ...topics, and their pedagogical content knowledge in teaching them. In view of the historical inequalities of the South African education system, a focus of the study was comparison of these perceptions of teachers based at schools which are diverse in terms of location, student population, and availability of resources. We adopted a mixed methods approach in collecting and analysing data from a large-scale survey of teachers through a structured questionnaire, and followed this with interviews with 10 teachers in seeking more in-depth explanations of the findings. The study revealed that teachers at township and rural schools previously designated for black students, and suburban and city schools previously reserved for white students, have a positive perception of the new topics introduced into the revised curriculum. However, teachers at all these schools expressed uncertainly as to their content knowledge and pedagogical knowledge of the new topics.
Films of (Zn,Cd)Se and ZnSe were electrodeposited from dimethylsulfoxide solutions of elemental Se and the perchlorates of Zn and Cd. The composition of the mixed selenides could be controlled by ...variation of the deposition current density, utilizing diffusion control of the low concentrations of Cd(ClO{sub 4}){sub 2}. The film composition was measured by X-ray photoelectron spectroscopy and compared with the measured bandgap values extracted from optical transmission spectra. Photoelectrochemical photocurrent spectroscopy and contact potential difference (Kelvin probe) measurements both showed changes in apparent conductivity type with Zn concentration in the electrolyte from n-type (low Zn) concentration to p-type (high Zn). This phenomenon is discussed in terms of preferential surface trapping of either electrons or holes at the nanocrystallite surface.
Epidermal growth factor (EGF) receptor from A-431 cells was purified by affinity chromatography with monoclonal anti-receptor antibodies. The purified radiolabeled receptor was incubated with EGF and ...then analyzed by gel electrophoresis under nondenaturing conditions. In these gels, the EGF receptor migrates in two forms: a fast-migrating (low) form and an EGF-induced slow-migrating (high) form. On the basis of the various control and calibration experiments described, it is concluded that the low form represents the monomeric 170-kilodalton EGF receptor and the high form represents an EGF receptor dimer. The binding of EGF causes a rapid, temperature-sensitive dimerization of the EGF receptor. Receptor dimerization is fully reversible and involves saturable, noncovalent interactions that are stable at neutral pH and in nonionic detergents. Both the monomeric and dimeric forms of the receptor bind EGF and undergo self-phosphorylation. The dimeric form of the receptor may possess higher ligand binding affinity, and it seems to be phosphorylated earlier than the monomeric form following the addition of EGF and gamma-32PATP. On the basis of these results, it is concluded that receptor oligomerization is an intrinsic property of the occupied EGF receptor and that it may play a role in the activation of the kinase function and the subsequent transmembrane signaling process.
The ethylene signal is transduced in plant cells via phosphorylation events. To identify protein kinases whose levels of expression are modulated by the plant hormone ethylene, we utilized a ...differential reverse transcriptase-polymerase chain reaction approach using mRNA extracted from ethylene-treated and untreated tobacco leaves. An ethylene-induced cDNA clone, PK12, encoding a protein kinase, was isolated. PK12 is a new member of the recently defined LAMMER family of protein kinases, which has been identified in mammals, flies, yeasts, and plants. The LAMMER kineses are related to the cell cycle-dependent CDC2-type kinases and are characterized by their similarity at kinase subdomain X. The recombinant PK12 protein autophosphorylates in vitro on serine, threonine, and tyrosine residues, thereby making it a member of the dual-specificity protein kinases. Immunoprecipitation of PK12 from plant extracts and kinase assay revealed that the apparent PK12 activity is rapidly and transiently increased when plants are treated with ethylene. By using in situ hybridization, we detected accumulation of the PK12 transcript in leaves after ethylene treatment and in the untreated flower abscission zone. The tissue in this zone is known to constitutively express ethylene-regulated genes.
The history of developing synergy between monoclonal antibodies, anti-tumor activity of monoclonal antibodies against tyrosine-kinases receptors EGFR/ErbB-1 and HER2/ErbB-2 as well as growth factor ...VEGF in various combinations are considered in the article. There were proposed hypotheses about potential molecular mechanisms underlay synergy between monoclonal antibodies (for homo- and hetero combinations of antibodies appropriately specific for antigenic determinants on the same or different receptors). The future trends in researches are necessary to understand the causes of this phenomenon; and the perspectives for practical application of monoclonal antibodies acted synergistically as immunotherapeutic drugs for human tumors treatment are reviewed.
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