Number-Based Visual Generalisation in the Honeybee

Although the numerical abilities of many vertebrate species have been investigated in the scientific literature, there are few convincing accounts of invertebrate numerical competence. Honeybees, Apis mellifera, by virtue of their other impressive cognitive feats, are a prime candidate for investigations of this nature. We therefore used the well-established delayed match-to-sample paradigm, to test the limits of honeybees'' ability to match two visual patterns solely on the basis of the shared number of elements in the two patterns. Using a y-maze, we found that bees can not only differentiate between patterns containing two and three elements, but can also use this prior knowledge to differentiate three from four, without any additional training. However, bees trained on the two versus three task could not distinguish between higher numbers, such as four versus five, four versus six, or five versus six. Control experiments confirmed that the bees were not using cues such as the colour of the exact configuration of the visual elements, the combined area or edge length of the elements, or illusory contours formed by the elements. To our knowledge, this is the first report of number-based visual generalisation by an invertebrate.     

Differential Roles of Arabidopsis Dynamin-Related Proteins DRP3A,DRP3B,and DRP5B in Organelle Division

Dynamin-related proteins (DRPs) are key components of the organelle division machineries, functioning as molecular scissors during the fission process. In Arabidopsis, DRP3A and DRP3B are shared by peroxisomal and mitochondrial division, whereas the structurally-distinct DRP5B (ARC5) protein is involved in the division of chloroplasts and peroxisomes. Here, we further investigated the roles of DRP3A, DRP3B, and DRP5B in organelle division and plant development. Despite DRP5B's lack of stable association with mitochondria, drp5B mutants show defects in mitochondrial division. The drp3A-2 drp3B-2 drp5B-2 triple mutant exhibits enhanced mitochondrial division phenotypes over drp3A-2 drp3B-2, but its peroxisomal morphology and plant growth phenotypes resemble those of the double mutant. We further demonstrated that DRP3A and DRP3B form a supercomplex in vivo, in which DRP3A is the major component, yet DRP5B is not a constituent of this complex. We thus conclude that DRP5B participates in the division of three types of organelles in Arabidopsis, acting independently of the DRP3 complex. Our findings will help elucidate the precise composition of the DRP3 complex at organelle division sites, and will be instrumental to studies aimed at understanding how the same protein mediates the morphogenesis of distinct organelles that are linked by metabolism.     

Vacuolar Ca2+/H+ transport activity is required for systemic phosphate homeostasis involving shoot-to-root signaling in Arabidopsis

Calcium ions (Ca(2+)) and Ca(2+)-related proteins mediate a wide array of downstream processes involved in plant responses to abiotic stresses. In Arabidopsis (Arabidopsis thaliana), disruption of the vacuolar Ca(2+)/H(+) transporters CAX1 and CAX3 causes notable alterations in the shoot ionome, including phosphate (P(i)) content. In this study, we showed that the cax1/cax3 double mutant displays an elevated P(i) level in shoots as a result of increased P(i) uptake in a miR399/PHO2-independent signaling pathway. Microarray analysis of the cax1/cax3 mutant suggests the regulatory function of CAX1 and CAX3 in suppressing the expression of a subset of shoot P(i) starvation-responsive genes, including genes encoding the PHT1;4 P(i) transporter and two SPX domain-containing proteins, SPX1 and SPX3. Moreover, although the expression of several PHT1 genes and PHT1;1/2/3 proteins is not up-regulated in the root of cax1/cax3, results from reciprocal grafting experiments indicate that the cax1/cax3 scion is responsible for high P(i) accumulation in grafted plants and that the pht1;1 rootstock is sufficient to moderately repress such P(i) accumulation. Based on these findings, we propose that CAX1 and CAX3 mediate a shoot-derived signal that modulates the activity of the root P(i) transporter system, likely in part via posttranslational regulation of PHT1;1 P(i) transporters.     

Studying Protein–DNA Complexes Using Gold Nanoparticles by Exploiting Particle Aggregation,Refractive Index Change,and Fluorescence Quenching and Enhancement Principles

Plasmonics - Gold nanoparticles (AuNPs) have a unique optical phenomena termed localized surface plasmon resonance that is determined by particle shape, size, interparticle distance (or aggregation...     

Effects of Solvent Additives on Morphology,Charge Generation,Transport, and Recombination in Solution‐Processed Small‐Molecule Solar Cells

The effects of solvent additive (1,8‐diiodooctane (DIO)) on the morphology, charge generation, transport, and recombination in solution‐processed small‐molecule solar cells are studied and these parameters are correlated with device performance. In the optimum nanoscale morphology, which is processed with 0.4% DIO, the phase separation is large enough to create a percolating pathway for carrier transport, yet still small enough to form large interfacial area for efficient charge separation. Complete phase separation in this film reduces the interfacial defects, which occurs without DIO, and hence suppresses the monomolecular recombination. Moreover, balanced charge transport and weak bimolecular recombination lead to a high fill factor (72%). On the other hand, an excess amount of DIO (0.8%) in the solvent results in the over‐aggregation of the donor phase, which disturbs the percolating pathway of the acceptor phase and reduces the electron mobility. The over‐aggregation of the donor phase also shrinks the interfacial area for charge separation and consequently reduces the photocurrent generation.     

Age-related differences in polyfunctional T cell responses

Background

A reduced number of naïve T cells along with an accumulation of differentiated cell types in aging have been described but little is known about the polyfunctionality of the T cell responses. In this study we compared the individual and polyfunctional expression of IFN-γ, MIP-1α, TNF-α, perforin, and IL-2 by T cell subsets, including the newly described stem cell like memory T cells (T_SCM), in response to stimulation with superantigen staphylococcal enterotoxin B (SEB) in older (median age 80, n?=?23) versus younger (median age 27; n?=?23) adults.

Results

Older age was associated with a markedly lower frequency of CD8+ naïve T cells (11% vs. 47%; p?<?0.0001) and an expansion in memory T cell subsets including central memory (p?<?0.05), effector memory and effector T cells (p?<?0.001 for both). There was also a decline in CD4+ naïve T cells in older subjects (33% vs. 45%; p?=?0.02). There were no differences in frequencies or polyfunctional profiles of T_SCM between groups. CD8+ naïve cells in the older group had increased expression of all functional parameters measured compared to the younger subjects and exhibited greater polyfunctionality (p?=?0.04). CD4+ naïve T cells in the older group also showed greater polyfunctionality with a TNF-α and IL-2 predominance (p?=?0.005). CD8+ effector memory and effector T cells exhibited increased polyfunctionality in the older group compared with younger (p?=?0.01 and p?=?0.003).

Conclusions

These data suggest that aging does not have a negative effect on polyfunctionality and therefore this is likely not a major contributor to the immunesenescence described with aging.

     

Safety and Effectiveness of Nitroprusside in Preventing No-Reflow During Percutaneous Coronary Intervention: A Systematic Review

The objective of this study was to evaluate the clinical efficacy and safety of nitroprusside injection for preventing the slow-flow/no-reflow phenomenon after percutaneous coronary intervention (PCI). We searched the Cochrane Central Register of Controlled Trials (Issue 2, 2011), PubMed, EMbase, and Google Scholar for data. Two reviewers independently evaluated the quality of the included studies and extracted the data. A meta-analysis was performed using RevMan 5.0 software. Four randomized controlled trials (RCTs) involving 319 patients were included. The results of the meta-analyses showed that intracoronary nitroprusside is beneficial in preventing no-reflow/slow-flow, in reducing corrected TIMI frame count, and in improving left ventricular ejection fraction. It also likely reduces adverse reactions in patients after PCI and rehospitalization due to cardiovascular events. However, we must caution that in this review, there is a moderate possibility of bias with regard to patient selection, performance, and publication because of the small number of included studies. A larger sample size and high-quality RCTs are needed for a more reassuring analysis.     

Hormones and young leaves control development of cotyledonary buds in tomato seedlings

Hormonal and plant factors regulating the development of the inhibited cotyledonary buds of Lycopersicon esculentum Mill. cv. `Fireball' seedlings were studied. Excision of the immature plumular leaves of 5- to 20- millimeter length significantly stimulated bud development after 2 to 4 days, but excision of leaves exceeding 20-millimeter length was without effect. Apical application of 20 microliters of 5 millimolar abscisic acid significantly promoted development of the cotyledonary buds after 6 days. A subapical ring of 0.1 millimolar concentration of 2,3,5-triiodobenzoic acid (TIBA) in lanolin significantly promoted cotyledonary bud development after 11 days. Twenty microliters of 0.1 millimolar 6-benzylaminopurine (BAP) applied directly to the cotyledonary bud loci significantly promoted bud development, but 1 micromolar gibberellin A_4/7 was ineffective. Application of 0.1 millimolar BAP in lanolin to the petiole or hypocotyl was ineffective. However, application of 0.1 millimolar TIBA as a ring around the petioles of the cotyledons or 1-centimeter on the hypocotyl below the cotyledons significantly promoted cotyledonary bud development.     

High prevalence of sulfadoxine/pyrimethamine resistance alleles in Plasmodium falciparum parasites from Bangladesh

In Bangladesh, despite the official introduction of artemisinin combination therapy in 2004, chloroquine+sulfadoxine/pyrimethamine has been used for the treatment of uncomplicated malaria. To assess the distribution of pfcrt, pfmdr1, dhfr, and dhps genotypes in Plasmodium falciparum, we conducted hospital- and community-based surveys in Bandarban, Bangladesh (near the border with Myanmar) in 2007 and 2008. Using nested PCR followed by digestion, 139 P. falciparum isolates were genotyped. We found fixation of a mutation at position 76 in pfcrt and low prevalence of a mutation at position 86 in pfmdr1. In dhfr, the highest pyrimethamine resistant genotype quadruple mutant was found in 19% of isolates, which is significantly higher prevalence than reported in a previous study in Khagrachari (1%) in 2002. Microsatellite haplotypes flanking dhfr of the quadruple mutants in Bangladesh were identical or very similar to those found in Thailand and Cambodia, indicating a common origin for the mutant in these countries. These observations suggest that the higher prevalence of the dhfr quadruple mutant in Bandarban is because of parasite migration from Myanmar. However, continuous use of sulfadoxine/pyrimethamine would have also played a role through selection for the dhfr quadruple mutant. These results indicate an urgent need to collect molecular epidemiological information regarding dhfr and dhps genes, and a review of current sulfadoxine/pyrimethamine usage with the aim of avoiding the widespread distribution of high levels of resistant parasites in Bangladesh.