Alternaria Brassicae Induced Changes in the Activity of Cell Wall Degrading Enzymes in Leaves of Brassica Juncea

After inoculation of Brassica juncea leaves with Alternaria brassicae, activities of the cell wall degrading enzymes, polygalacturonase (EC 3.2.1.15) and cellulase (EC 3.2.1.4) decreased in leaf blight resistant cultivar RC-781 and increased in the susceptible cultivar Varuna upto 3 d. In the leaves of both the cultivars 11 poly-peptides were observed in the absence of A. brassicae inoculation. After inoculation in the resistant cultivar RC-781 there was no change in the polypeptide pattern, while in the susceptible cultivar Varuna, four polypeptides (43.7 to 58.8 kDa) disappeared only at 3^rd day after inoculation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Noninvasive Neutron Scattering Measurements Reveal Slower Cholesterol Transport in Model Lipid Membranes

Proper cholesterol transport is essential to healthy cellular activity and any abnormality can lead to several fatal diseases. However, complete understandings of cholesterol homeostasis in the cell remains elusive, partly due to the wide variability in reported values for intra- and intermembrane cholesterol transport rates. Here, we used time-resolved small-angle neutron scattering to measure cholesterol intermembrane exchange and intramembrane flipping rates, in situ, without recourse to any external fields or compounds. We found significantly slower transport kinetics than reported by previous studies, particularly for intramembrane flipping where our measured rates are several orders of magnitude slower. We unambiguously demonstrate that the presence of chemical tags and extraneous compounds employed in traditional kinetic measurements dramatically affect the system thermodynamics, accelerating cholesterol transport rates by an order of magnitude. To our knowledge, this work provides new insights into cholesterol transport process disorders, and challenges many of the underlying assumptions used in most cholesterol transport studies to date.     

Induced Mutation inPetunia nyctaginiflora JUSS.

Seeds ofPetunia nyctaginifloraJuss. a common ornamental garden plant, were treated with two alkylating agents (methyl methane sulphonate and N-methyl-N’-nitro-N-nitrosoguanidine). Six morphological and seven chlorophyll mutants were isolated from M₂ segregating families. The isolated induced mutants are described and genetically analysed.     

An Appended Domain Results in an Unusual Architecture for Malaria Parasite Tryptophanyl-tRNA Synthetase

Specific activation of amino acids by aminoacyl-tRNA synthetases (aaRSs) is essential for maintaining fidelity during protein translation. Here, we present crystal structure of malaria parasite Plasmodium falciparum tryptophanyl-tRNA synthetase (Pf-WRS) catalytic domain (AAD) at 2.6 Å resolution in complex with L-tryptophan. Confocal microscopy-based localization data suggest cytoplasmic residency of this protein. Pf-WRS has an unusual N-terminal extension of AlaX-like domain (AXD) along with linker regions which together seem vital for enzymatic activity and tRNA binding. Pf-WRS is not proteolytically processed in the parasites and therefore AXD likely provides tRNA binding capability rather than editing activity. The N-terminal domain containing AXD and linker region is monomeric and would result in an unusual overall architecture for Pf-WRS where the dimeric catalytic domains have monomeric AXDs on either side. Our PDB-wide comparative analyses of 47 WRS crystal structures also provide new mechanistic insights into this enzyme family in context conserved KMSKS loop conformations.     

Asoprisnil (J867): a selective progesterone receptor modulator for gynecological therapy

Asoprisnil is a novel selective steroid receptor modulator that shows unique pharmacodynamic effects in animal models and humans. Asoprisnil, its major metabolite J912, and structurally related compounds represent a new class of progesterone receptor (PR) ligands that exhibit partial agonist and antagonist activities in vivo. Asoprisnil demonstrates a high degree of receptor and tissue selectivity, with high-binding affinity for PR, moderate affinity for glucocorticoid receptor (GR), low affinity for androgen receptor (AR), and no binding affinity for estrogen or mineralocorticoid receptors. In the rabbit endometrium, both asoprisnil and J912 induce partial agonist and antagonist effects. Asoprisnil induces mucification of the guinea pig vagina and has pronounced anti-uterotrophic effects in normal and ovariectomized guinea pigs. Unlike antiprogestins, asoprisnil shows only marginal labor-inducing activity during mid-pregnancy and is completely ineffective in inducing preterm parturition in the guinea pig. Asoprisnil exhibits only marginal antiglucocorticoid activity in transactivation in vitro assays and animal models. In male rats, asoprisnil showed weak androgenic and anti-androgenic properties. In toxicological studies in female cynomolgus monkeys, asoprisnil treatment abolished menstrual cyclicity and endometrial atrophy. Early clinical studies of asoprisnil in normal volunteers demonstrated a dose-dependent suppression of menstruation irrespective of the effects on ovulation, with no change in basal estrogen concentrations and no antiglucocorticoid effects. Unlike progestins, asoprisnil does not induce breakthrough bleeding. With favorable safety and tolerability profiles thus far, asoprisnil appears promising as a novel treatment of gynecological disorders, such as uterine fibroids and endometriosis.     

Role of NK cell-activating receptors and their ligands in the lysis of mononuclear phagocytes infected with an intracellular bacterium

We studied the role of NK cell-activating receptors and their ligands in the lysis of mononuclear phagocytes infected with the intracellular pathogen Mycobacterium tuberculosis. Expression of the activating receptors NKp30, NKp46, and NKG2D were enhanced on NK cells by exposure to M. tuberculosis-infected monocytes, whereas expression of DNAX accessory molecule-1 and 2B4 was not. Anti-NKG2D and anti-NKp46 inhibited NK cell lysis of M. tuberculosis-infected monocytes, but Abs to NKp30, DNAX accessory molecule-1, and 2B4 had no effect. Infection of monocytes up-regulated expression of the NKG2D ligand, UL-16 binding protein (ULBP)1, but not expression of ULBP2, ULBP3, or MHC class I-related chain A or chain B. Up-regulation of ULBP1 on infected monocytes was dependent on TLR2, and anti-ULBP1 abrogated NK cell lysis of infected monocytes. The dominant roles of NKp46, NKG2D, and ULBP1 were confirmed for NK cell lysis of M. tuberculosis-infected alveolar macrophages. We conclude that NKp46 and NKG2D are the principal receptors involved in lysis of M. tuberculosis-infected mononuclear phagocytes, and that ULBP1 on infected cells is the major ligand for NKG2D. Furthermore, TLR2 contributes to up-regulation of ULBP1 expression.     

Unraveling the differential structural stability and dynamics features of T7 endolysin partially folded conformations

Background

Characterization of partially collapsed protein conformations at atomic level is a daunting task due to their inherent flexibility and conformational heterogeneity. T7 bacteriophage endolysin (T7L) is a single-domain amidase that facilitates the lysis of Gram-negative bacteria. T7L exhibits a pH-dependent structural transition from native state to partially folded (PF) conformation. In the pH range 5–3, T7L PF states display differential ANS binding characteristics.

Teaching medical students how to break bad news

PROGRAM OBJECTIVE: To teach medical students to break bad news to patients and their families empathically and competently. SETTING: Seven teaching hospitals affiliated with the University of Toronto since 1987. PARTICIPANTS: All medical students in their third preclinical year. PROGRAM: The course presents a 6-point protocol to guide students in breaking bad news and comprises 2 half-day (3-hour) teaching sessions. Each session incorporates a video presentation, a discussion period and small-group teaching, consisting of exercises followed by 4 different role-playing scenarios conducted with the use of standardized patients. The course was evaluated through 2 questionnaires, 1 administered before and 1 after the course, which measured changes in the students'' attitude and strategy. Questionnaires were administered during 5 of the years since the course was started. A total of 914 precourse and 503 postcourse questionnaires were completed, of which 359 matched pairs of precourse and postcourse questionnaires were analysed to study any changes due to the course. OUTCOMES: Precourse questionnaires showed that 68% of the students had thought about the task of breaking bad news often or very often. Of the 56% of students who had seen clinicians performing this task, 75% felt that they had seen good examples. The proportion of the students who had a plan for how to conduct such an interview rose from 49% before the course to 92% after it, and the proportion who felt they might be reasonably competent in breaking bad news rose from 23% before the course to 74% after it. CONCLUSIONS: The subject of breaking bad news is important to medical students, and it is practicable to design a course to teach the basic techniques involved. Most students perceive such a course as enjoyable and useful and find that it increases their sense of competence and their ability to formulate a strategy for such situations.