Two distinct visual motion mechanisms for smooth pursuit: evidence from individual differences

Smooth-pursuit eye velocity to a moving target is more accurate after an initial catch-up saccade than before, an enhancement that is poorly understood. We present an individual-differences-based method for identifying mechanisms underlying a physiological response and use it to test whether visual motion signals driving pursuit differ pre- and postsaccade. Correlating moment-to-moment measurements of pursuit over time with two psychophysical measures of speed estimation during fixation, we find two independent associations across individuals. Presaccadic pursuit acceleration is predicted by the precision of low-level (motion-energy-based) speed estimation, and postsaccadic pursuit precision is predicted by the precision of high-level (position-tracking) speed estimation. These results provide evidence that a low-level motion signal influences presaccadic acceleration and an independent high-level motion signal influences postsaccadic precision, thus presenting a plausible mechanism for postsaccadic enhancement of pursuit.     

Regulation of adipocytokine secretion and adipocyte hypertrophy by polymethoxyflavonoids, nobiletin and tangeretin

AimsThe polymethoxyflavonoids nobiletin and tangeretin possess several important biological properties such as neuroprotective, antimetastatic, anticancer, and anti-inflammatory properties. The present study was undertaken to examine whether nobiletin and tangeretin could modulate adipocytokine secretion and to evaluate the effects of these flavonoids on the hypertrophy of mature adipocytes.Main methodsAll experiments were performed on the murine preadipocyte cell line 3T3-L1. We studied the formation of intracellular lipid droplets in adipocytes and the apoptosis-inducing activity to evaluate the effects of polymethoxyflavonoids on adipocyte differentiation and hypertrophy, respectively. The secretion of adipocytokines was measured using ELISA.Key findingsWe demonstrated that the combined treatment of differentiation reagents with nobiletin or tangeretin differentiated 3T3-L1 preadipocytes into adipocytes possessing less intracellular triglyceride as compared to vehicle-treated differentiated 3T3-L1 adipocytes. Both flavonoids increased the secretion of an insulin-sensitizing factor, adiponectin, but concomitantly decreased the secretion of an insulin-resistance factor, MCP-1, in 3T3-L1 adipocytes. Furthermore, nobiletin was found to decrease the secretion of resistin, which serves as an insulin-resistance factor. In mature 3T3-L1 adipocytes, nobiletin induced apoptosis; tangeretin, in contrast, did not induce apoptosis, but suppressed further triglyceride accumulation.SignificanceOur results suggest that nobiletin and tangeretin are promising therapeutic candidates for the prevention and treatment of insulin resistance by modulating the adipocytokine secretion balance. We also demonstrated the different effects of nobiletin and tangeretin on mature adipocytes.     

The association between the phytoplankton, Rhopalosolen species (Chlorophyta; Chlorophyceae), and Anopheles gambiae sensu lato (Diptera: Culicidae) larval abundance in western Kenya

Algae are important food resources of the larvae of the African malaria vectors, Anopheles gambiae Giles and Anopheles arabiensis Patton (Anopheles gambiae sensu lato), and other zooplankton, but empirical evidence remains meager about the agal flora in ephemeral water bodies. The animals present in natural aquatic habitats in western Kenya were sampled from July to November 2002 to study abiotic and biotic environmental factors determining A. gambiae sl larval abundance. The five highest concentrations of third and fourth instars and pupae (hereafter referred to as old-stage larvae) were sampled in conjunction with the unicellular epizoic green algae, Rhopalosolen species (Chlorophyta; Chlorophyceae). Canonical correspondence analysis revealed that the presence of Rhopalosolen species was the most important determinant of the animal assemblage. The density of old-stage A. gambiae sl larvae was positively correlated with the presence of Rhopalosolen species, but the density of first and second instars of A. gambiae sl was not. The water bodies with Rhopalosolen sp. yielded larger mosquitoes in spite of the higher density of larvae. We demonstrated that the productivity of water bodies in terms of the larvae of malaria vectors can differ in magnitude depending on the agal flora. We discuss phytoplankton as a regulator of mosquito larval populations.     

An integrated database of the ascidian, Ciona intestinalis: towards functional genomics

An integrated genome database is essential for future studies of functional genomics. In this study, we update cDNA and genomic resources of the ascidian, Ciona intestinalis, and provide an integrated database of the genomic and cDNA data by extending a database published previously. The updated resources include over 190,000 ESTs (672,396 in total together with the previous ESTs) and over 1,000 full-insert sequences (6,773 in total). In addition, results of mapping information of the determined scaffolds onto chromosomes, ESTs from a full-length enriched cDNA library for indication of precise 5'-ends of genes, and comparisons of SNPs and indels among different individuals are integrated into this database, all of these results being reported recently. These advances continue to increase the utility of Ciona intestinalis as a model organism whilst the integrated database will be useful for researchers in comparative and evolutionary genomics.     

T cell hyporesponsiveness induced by oral administration of ovalbumin is associated with impaired NFAT nuclear translocation and p27kip1 degradation

Oral tolerance is an important physiological component of the immune system whereby the organism avoids dangerous reactions such as hypersensitivity to ingested food proteins and other luminal Ags which may cause tissue damage and inflammation. In addition, it has been shown in animal models and in humans that oral tolerance can be applied to controlling undesired immune responses, including autoimmune diseases, allergies, and organ transplant rejections. However, the molecular mechanisms of oral tolerance have been poorly defined. In this study, we investigated the molecular basis underlying the hyporesponsiveness of orally tolerant CD4 T cells using a TCR transgenic mouse system in which oral tolerance was induced by long-term feeding with high dose Ag. We demonstrate that the hyporesponsive state of the CD4 T cells was maintained by a selective impairment in the TCR-induced calcium/NFAT signaling pathway and in the IL-2R-induced degradation of p27(kip1) and cell cycle progression. Thus, physiological mucosal tolerance is revealed to be associated with a unique type of T cell hyporesponsiveness which differs from previously described anergic T cells.     

Hsp105α suppresses Adriamycin-induced cell death via nuclear localization signal-dependent nuclear accumulation

Heat shock protein 105 (Hsp105) is a molecular chaperone, and the isoforms Hsp105α and Hsp105β exhibit distinct functions with different subcellular localizations. Hsp105β localizes in the nucleus and induces the expression of the major heat shock protein Hsp70, whereas cytoplasmic Hsp105α is less effective in inducing Hsp70 expression. Hsp105 shuttles between the cytoplasm and the nucleus; the subcellular localization is governed by the relative activities of the nuclear localization signal (NLS) and nuclear export signal (NES). Here, we show that nuclear accumulation of Hsp105α but not Hsp105β is involved in Adriamycin (ADR) sensitivity. Knockdown of Hsp105α induces cell death at low ADR concentration, at which ADR is less effective in inducing cell death in the presence of Hsp105α. Of note, Hsp105 is localized in the nucleus under these conditions, even though Hsp105β is not expressed, indicating that Hsp105α accumulates in the nucleus in response to ADR treatment. The exogenously expressed Hsp105α but not its NLS mutant localizes in the nucleus of ADR-treated cells. In addition, the expression level of the nuclear export protein chromosomal maintenance 1 (CRM1) was decreased by ADR treatment of cells, and CRM1 knockdown caused nuclear accumulation of Hsp105α both in the presence and absence of ADR. These results indicating that Hsp105α accumulates in the nucleus in a manner dependent on the NLS activity via the suppression of nuclear export. Our findings suggest a role of nuclear Hsp105α in the sensitivity against DNA-damaging agents in tumor cells.