Influence of temperature on the reproductive and demographic parameters of two spider mite pests of vineyards and their natural predator

This research was supported by scholarships to MC Stavrinides from the Robert and Peggy van den Bosch Memorial Scholarship in Biological Control and the Cyprus-America Scholarship program administered by the Fulbright Commission in Cyprus. Funding was also provided by the American Vineyard Foundation, the Viticulture Consortium West and the California Raisin Marketing Board. We thank A. Goldman, J. King, R. Lara and the undergraduate research apprentices who helped with laboratory observations. Steve Welter and Wayne Sousa read earlier versions of this manuscript and provided comments for its improvement. We also thank Duarte nurseries for supplying grape plants for this study.We evaluated the influence of temperature on demographic parameters of two common vineyard pests, the Pacific spider mite, Tetranychus pacificus McGregor, and the Willamette spider mite, Eotetranychus willamettei (McGregor) (Acari: Tetranychidae). Additionally, we investigated the effects of temperature on their shared predator, the western predatory mite, Galendromus occidentalis (Nesbitt) (Acari: Phytoseiidae). The intrinsic rate of increase (r (m) ) was higher for T. pacificus than E. willamettei at 15 and 28A degrees C, but similar at 22A degrees C. G. occidentalis achieved a higher r (m) than T. pacificus from 15 to 28A degrees C, but the difference was significant only at 22A degrees C. At 34A degrees C, the r (m) for both T. pacificus and G. occidentalis was negative, while E. willamettei did not develop at this temperature. Prey species did not affect demographic parameters of G. occidentalis. These results suggest that higher temperatures favor T. pacificus over the less damaging E. willamettei, and may also reduce the effectiveness of G. occidentalis.Robert and Peggy van den Bosch Memorial Scholarship in Biological Control, Cyprus-America Scholarship, American Vineyard Foundation, Viticulture Consortium West, California Raisin Marketing Boar

G protein signaling in the parasite Entamoeba histolytica

The parasite Entamoeba histolytica causes amebic colitis and systemic amebiasis. Among the known amebic factors contributing to pathogenesis are signaling pathways involving heterotrimeric and Ras superfamily G proteins. Here, we review the current knowledge of the roles of heterotrimeric G protein subunits, Ras, Rho and Rab GTPase families in E. histolytica pathogenesis, as well as of their downstream signaling effectors and nucleotide cycle regulators. Heterotrimeric G protein signaling likely modulates amebic motility and attachment to and killing of host cells, in part through activation of an RGS-RhoGEF (regulator of G protein signaling–Rho guanine nucleotide exchange factor) effector. Rho family GTPases, as well as RhoGEFs and Rho effectors (formins and p21-activated kinases) regulate the dynamic actin cytoskeleton of E. histolytica and associated pathogenesis-related cellular processes, such as migration, invasion, phagocytosis and evasion of the host immune response by surface receptor capping. A remarkably large family of 91 Rab GTPases has multiple roles in a complex amebic vesicular trafficking system required for phagocytosis and pinocytosis and secretion of known virulence factors, such as amebapores and cysteine proteases. Although much remains to be discovered, recent studies of G protein signaling in E. histolytica have enhanced our understanding of parasitic pathogenesis and have also highlighted possible targets for pharmacological manipulation

The importance of cohort studies in the post-GWAS era

The past decade has seen enormous success of wide-scale genetic studies in identifying genetic variants that modify individuals' predisposition to common diseases. However, the interpretation and functional understanding of these variants lag far behind. In this Perspective, we discuss opportunities for using large-scale cohort studies to investigate the downstream molecular effects of SNPs at different 'omics' data levels. We point to the pivotal role of population cohorts in establishing causality and advancing drug discovery. In particular, we focus on the breadth-versus-depth concepts of population studies, on data harmonization, and on the challenges, ethical aspects and future perspectives of cohort studies