Dominant negative alleles of SEC10 reveal distinct domains involved in secretion and morphogenesis in yeast

The accurate targeting of secretory vesicles to distinct sites on the plasma membrane is necessary to achieve polarized growth and to establish specialized domains at the surface of eukaryotic cells. Members of a protein complex required for exocytosis, the exocyst, have been localized to regions of active secretion in the budding yeast Saccharomyces cerevisiae where they may function to specify sites on the plasma membrane for vesicle docking and fusion. In this study we have addressed the function of one member of the exocyst complex, Sec10p. We have identified two functional domains of Sec10p that act in a dominant-negative manner to inhibit cell growth upon overexpression. Phenotypic and biochemical analysis of the dominant-negative mutants points to a bifunctional role for Sec10p. One domain, consisting of the amino-terminal two-thirds of Sec10p directly interacts with Sec15p, another exocyst component. Overexpression of this domain displaces the full-length Sec10 from the exocyst complex, resulting in a block in exocytosis and an accumulation of secretory vesicles. The carboxy-terminal domain of Sec10p does not interact with other members of the exocyst complex and expression of this domain does not cause a secretory defect. Rather, this mutant results in the formation of elongated cells, suggesting that the second domain of Sec10p is required for morphogenesis, perhaps regulating the reorientation of the secretory pathway from the tip of the emerging daughter cell toward the mother-daughter connection during cell cycle progression.     

SEC6 encodes an 85 kDa soluble protein required for exocytosis in yeast.

The SEC6 gene encodes a protein required for an event leading to fusion of post-Golgi vesicles with the plasma membrane in Saccharomyces cerevisiae cells. The gene was cloned by complementation of the temperature-sensitive growth defect of a sec6-4 strain. The nucleotide sequence was determined and the longest open reading frame was found to encode an 85 kDa protein of 733 amino acids. The Sec6 protein is predicted to be hydrophilic and is found predominantly in the soluble fraction of a yeast lysate, in a species that sediments with a coefficient of 14S. No extensive homology was found with known proteins of the database. Gene disruption and marker rescue experiments indicate that SEC6 is a single copy gene essential for growth. Overproduction of Sec6p does not suppress any of the other late-acting sec mutants, yet sec6-4 does display synthetic lethality with sec8-9, suggesting that the two gene products may fulfill inter-related functions.     

Plasmid-protein relaxation complexes in Staphylococcus aureus

Protein-deoxyribonucleic acid relaxation complexes have been demonstrated for six Staphylococcus aureus plasmids out of sixteen examined. Four of these encode stretomycin resistence, have molecular weights of about 2.7 x 10(6), and are isolated as supercoiled molecules that are virtally 100% relaxable by treatment with sodium dodecyl sulfate. It is probable that these four isolates represent a single widely disseminated plasmid species. The other two plasmids showing relaxation complexes have molecular weights of about 3 x 10(6) and encode chloramphenicol resistance. The complexes in these cases are unstable, and it has not been possible to induce more than 50% relaxation by any of the standard treatments. Ten other plasmids do not show detectable complexes. These include three penicillinase plasmids, four tetracycline-resistance plasmids, one plasmid carrying kanamycin-neomycin resistance, and finally, two chloramphenicol-resistance plasmids.     

N‐Arylsulfonyl Indolines as Retinoic Acid Receptor‐Related Orphan Receptor γ (RORγ) Agonists

The nuclear retinoic acid receptor‐related orphan receptor γ (RORγ; NR1F3) is a key regulator of inflammatory gene programs involved in T helper 17 (T_H17) cell proliferation. As such, synthetic small‐molecule repressors (inverse agonists) targeting RORγ have been extensively studied for their potential as therapeutic agents for various autoimmune diseases. Alternatively, enhancing T_H17 cell proliferation through activation (agonism) of RORγ may boost an immune response, thereby offering a potentially new approach in cancer immunotherapy. Herein we describe the development of N‐arylsulfonyl indolines as RORγ agonists. Structure–activity studies reveal a critical linker region in these molecules as the major determinant for agonism. Hydrogen/deuterium exchange coupled to mass spectrometry (HDX‐MS) analysis of RORγ–ligand complexes help rationalize the observed results.     

Possible impacts of floods and droughts on water quality

The gradual climate change symptoms in many places on Earth have been observed during the last 20 years. There is a significant increase in frequency and extremity of meteorological and hydrological events (EEA, 2007) that lead to distinct excess or lack of water in landscape. These phenomena affect not only actual quantity of water but also its quality with direct and indirect impacts on aquatic organisms. From the environmental impact point of view, drought events are considered to be more dangerous due to their medium-term to long-term characteristics and large spatial impacts. However, this study presents that the particular flood event had significantly greater impact on water quality than the period of drought even if for only a very short time The paper reviews changes in water quality with all its consequences during selected extreme hydrological situations in the Czech Republic in last 10 years and compares them with the knowledge of impacts of floods and droughts on water quality collected from literature.     

QUICK: a tool for graphical user-interface construction by non-programmers

The last decade has placed the superiority of graphical user interfaces over traditional text-based approaches beyond dispute. In almost all contexts, users have found graphical interfaces easier to learn, faster to use, and less error-prone. However, it has been shown that the creation of powerful graphical interfaces takes up to 80% of the time required to develop an application. In our work, we seek to extend the benefits of graphical interaction to the next layer of computer user—the interface designer. Our work in this area is distinguished from other efforts by two important differences. First, while other efforts focus primarily on the design of standard user interfaces, our approach emphasizes the creation of unique and innovative interfaces by supporting, among other things, arbitrary user-designed graphical representations, direct specification of animation, and digitized sound. Second, our goal is to cater to the nonprogrammer. Thus, we address a challenging trade-off: maximizing power and flexibility in an extremely simple environment. We explore the utility of the prototype object-oriented paradigm, a high-level userinterface language, and a direct-manipulation programming environment in this context.     

Covariation in natural causal induction.

The covariation component of everyday causal inference has been depicted, in both cognitive and social psychology as well as in philosophy, as heterogeneous and prone to biases. The models and biases discussed in these domains are analyzed with respect to focal sets: contextually determined sets of events over which covariation is computed. Moreover, these models are compared to the authors' probabilistic contrast model, which specifies causes as first and higher order contrasts computed over events in a focal set. Contrary to the previous depiction of covariation computation, the present assessment indicates that a single normative mechanism, the computation of probabilistic contrasts, underlies this essential component of natural causal induction both in everyday and in scientific situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double patch closure of ventricular septal defect with increased pulmonary vascular resistance

BACKGROUND: Closure of a large ventricular septal defect (VSD) in children with elevated pulmonary vascular resistance is associated with significant morbidity and mortality. Pulmonary hypertensive episodes continue to be a major cause of postoperative morbidity and mortality. We designed a fenestrated flap valve double VSD patch in an effort to decrease the morbidity and mortality associated with the closure of a large VSD with elevated pulmonary vascular resistance. METHODS: Eighteen children (mean age, 5.7 years) with a large VSD and elevated pulmonary vascular resistance (mean, 11.4 Wood units) underwent double patch VSD closure using moderately hypothermic cardiopulmonary bypass and cardioplegic arrest. The routine VSD patch was fenestrated (4 to 6 mm) and on the left ventricular side of the patch, a second, smaller patch was attached to the fenestration along its superior margin before closure of the VSD. RESULTS: All children survived operation and were weaned from inotropic and ventilator support within 48 hours postoperatively. Postoperative pulmonary artery pressures were significantly lower than preoperative values. One child died 9 months postoperatively. CONCLUSIONS: Closure of a large VSD in children with elevated pulmonary vascular resistance can be performed with low morbidity and mortality when a flap valve double VSD patch is used.