Honey bees increase their foraging performance and frequency of pollen trips through experience.

Honey bee foragers must supply their colony with a balance of pollen and nectar to sustain optimal colony development. Inter-individual behavioural variability among foragers is observed in terms of activity levels and nectar vs. pollen collection, however the causes of such variation are still open questions.

Temporal correlation of elevated PRMT1 gene expression with mushroom body neurogenesis during bumblebee brain development.

Neural development depends on the controlled proliferation and differentiation of neural precursors. In holometabolous insects, these processes must be coordinated during larval and pupal development. Recently, protein arginine methylation has come into focus as an important mechanism of controlling neural stem cell proliferation and differentiation in mammals.

Harmonic radar tracking reveals random dispersal pattern of bumblebee (Bombus terrestris) queens after hibernation.

The dispersal of animals from their birth place has profound effects on the immediate survival and longer-term persistence of populations. Molecular studies have estimated that bumblebee colonies can be established many kilometers from their queens' natal nest site. However, little is known about when and how queens disperse during their lifespan.

How foresight might support the behavioral flexibility of arthropods.

The small brains of insects and other invertebrates are often thought to constrain these animals to live entirely 'in the moment'. In this view, each one of their many seemingly hard-wired behavioral routines is triggered by a precisely defined environmental stimulus configuration, but there is no mental appreciation of the possible outcomes of one's actions, and therefore little flexibility. However, many studies show problem-solving behavior in various arthropod species that falls outside the range of fixed behavior routines.

Large-scale transcriptome changes in the process of long-term visual memory formation in the bumblebee, Bombus terrestris.

Many genes have been implicated in mechanisms of long-term memory formation, but there is still much to be learnt about how the genome dynamically responds, transcriptionally, during memory formation. In this study, we used high-throughput sequencing to examine how transcriptome profiles change during visual memory formation in the bumblebee (Bombus terrestris). Expression of fifty-five genes changed immediately after bees were trained to associate reward with a single coloured chip, and the upregulated genes were predominantly genes known to be involved in signal transduction.

Studying emotion in invertebrates: what has been done, what can be measured and what they can provide.

Until recently, whether invertebrates might exhibit emotions was unknown. This possibility has traditionally been dismissed by many as emotions are frequently defined with reference to human subjective experience, and invertebrates are often not considered to have the neural requirements for such sophisticated abilities. However, emotions are understood in humans and other vertebrates to be multifaceted brain states, comprising dissociable subjective, cognitive, behavioural and physiological components.

A possible structural correlate of learning performance on a colour discrimination task in the brain of the bumblebee.

Synaptic plasticity is considered to be a basis for learning and memory. However, the relationship between synaptic arrangements and individual differences in learning and memory is poorly understood. Here, we explored how the density of microglomeruli (synaptic complexes) within specific regions of the bumblebee () brain relates to both visual learning and inter-individual differences in learning and memory performance on a visual discrimination task.

Correction: Associative Mechanisms Allow for Social Learning and Cultural Transmission of String Pulling in an Insect.

[This corrects the article DOI: 10.1371/journal.pbio.

Associative Mechanisms Allow for Social Learning and Cultural Transmission of String Pulling in an Insect.

Social insects make elaborate use of simple mechanisms to achieve seemingly complex behavior and may thus provide a unique resource to discover the basic cognitive elements required for culture, i.e., group-specific behaviors that spread from "innovators" to others in the group via social learning.

Accelerated behavioural development changes fine-scale search behaviour and spatial memory in honey bees (Apis mellifera L.).

Normally, worker honey bees (Apis mellifera) begin foraging when more than 2 weeks old as adults, but if individual bees or the colony is stressed, bees often begin foraging precociously. Here, we examined whether bees that accelerated their behavioural development to begin foraging precociously differed from normal-aged foragers in cognitive performance. We used a social manipulation to generate precocious foragers from small experimental colonies and tested their performance in a free-flight visual reversal learning task, and a test of spatial memory.

Negative impact of manganese on honeybee foraging.

Anthropogenic accumulation of metals such as manganese is a well-established health risk factor for vertebrates. By contrast, the long-term impact of these contaminants on invertebrates is mostly unknown. Here, we demonstrate that manganese ingestion alters brain biogenic amine levels in honeybees and fruit flies.

Rapid behavioral maturation accelerates failure of stressed honey bee colonies.

Many complex factors have been linked to the recent marked increase in honey bee colony failure, including pests and pathogens, agrochemicals, and nutritional stressors. It remains unclear, however, why colonies frequently react to stressors by losing almost their entire adult bee population in a short time, resulting in a colony population collapse. Here we examine the social dynamics underlying such dramatic colony failure.

Peak shift in honey bee olfactory learning.

If animals are trained with two similar stimuli such that one is rewarding (S+) and one punishing (S-), then following training animals show a greatest preference not for the S+, but for a novel stimulus that is slightly more different from the S- than the S+ is. This peak shift phenomenon has been widely reported for vertebrates and has recently been demonstrated for bumblebees and honey bees. To explore the nature of peak shift in invertebrates further, here we examined the properties of peak shift in honey bees trained in a free-flight olfactory learning assay.

Honey bees selectively avoid difficult choices.

Human decision-making strategies are strongly influenced by an awareness of certainty or uncertainty (a form of metacognition) to increase the chances of making a right choice. Humans seek more information and defer choosing when they realize they have insufficient information to make an accurate decision, but whether animals are aware of uncertainty is currently highly contentious. To explore this issue, we examined how honey bees (Apis mellifera) responded to a visual discrimination task that varied in difficulty between trials.

Invertebrate learning and cognition: relating phenomena to neural substrate.

Diverse invertebrate species have been used for studies of learning and comparative cognition. Although we have gained invaluable information from this, in this study we argue that our approach to comparative learning research is rather deficient. Generally invertebrate learning research has focused mainly on arthropods, and most of that within the Hymenoptera and Diptera.

Neural mechanisms of reward in insects.

Reward seeking is a major motivator and organizer of behavior, and animals readily learn to modify their behavior to more easily obtain reward, or to respond to stimuli that are predictive of reward. Here, we compare what is known of reward processing mechanisms in insects with the well-studied vertebrate reward systems. In insects almost all of what is known of reward processing is derived from studies of reward learning.

Rats can make relative perceptual judgments about sequential stimuli.

In their natural environment, animals often make decisions based on abstract relationships among multiple stimulus representations. Humans and other primates can determine not only whether a sensory stimulus differs from a remembered sensory representation, but also how they differ along a particular dimension. However, much remains unknown about how such relative comparisons are made, and which species share this capacity, in part because most studies of sensory-guided decision making have utilized instrumental tasks in which choices are based on very simple stimulus-response associations.

PKC{alpha}{beta}{gamma}- and PKC{delta}-dependent endocytosis of NBCe1-A and NBCe1-B in salivary parotid acinar cells.

We examined membrane trafficking of NBCe1-A and NBCe1-B variants of the electrogenic Na(+)-HCO(3)(-) cotransporter (NBCe1) encoded by the SLC4A4 gene, using confocal fluorescent microscopy in rat parotid acinar cells (ParC5 and ParC10). We showed that yellow fluorescent protein (YFP)-tagged NBCe1-A and green fluorescent protein (GFP)-tagged NBCe1-B are colocalized with E-cadherin in the basolateral membrane (BLM) but not with the apical membrane marker zona occludens 1 (ZO-1). We inhibited constitutive recycling with monensin and W13 and detected that NBCe1-A and NBCe1-B accumulated in vesicles marked with the early endosomal marker early endosome antigen-1 (EEA1), with a parallel loss from the BLM.

Electrogenic NBCe1 (SLC4A4), but not electroneutral NBCn1 (SLC4A7), cotransporter undergoes cholinergic-stimulated endocytosis in salivary ParC5 cells.

Cholinergic agonists are major stimuli for fluid secretion in parotid acinar cells. Saliva bicarbonate is essential for maintaining oral health. Electrogenic and electroneutral Na(+)-HCO(3)(-) cotransporters (NBCe1 and NBCn1) are abundant in parotid glands.

ANG II and calmodulin/CaMKII regulate surface expression and functional activity of NBCe1 via separate means.

We recently reported that ANG II inhibits NBCe1 current and surface expression in Xenopus laevis oocytes (Perry C, Blaine J, Le H, and Grichtchenko II. Am J Physiol Renal Physiol 290: F417-F427, 2006). Here, we investigated mechanisms of ANG II-induced changes in NBCe1 surface expression.

Clathrin-mediated endocytosis of the epithelial sodium channel. Role of epsin.

Here we present evidence that the epithelial sodium channel (ENaC), a heteromeric membrane protein whose surface expression is regulated by ubiquitination, is present in clathrin-coated vesicles in epithelial cells that natively express ENaC. The channel subunits are ubiquitinated and co-immunoprecipitate with both epsin and clathrin adaptor proteins, and epsin, as expected, co-immunoprecipitates with clathrin adaptor proteins. The functional significance of these interactions was evaluated in a Xenopus oocyte expression system where co-expression of epsin and ENaC resulted in a down-regulation of ENaC activity; conversely, co-expression of epsin sub-domains acted as dominant-negative effectors and stimulated ENaC activity.

Regulation of epithelial Na+ channels (ENaC) by methylation: a novel methyltransferase stimulates ENaC activity.

Aldosterone acts to increase apical membrane permeability by activation of epithelial Na(+) channels (ENaC). We have previously shown that aldosterone activates ENaC early in the course of its action by stimulating the methylation of the beta subunit of this heteromeric channel in A6 cells. Aldosterone also stimulates the expression and methylation of k-ras in A6 cells.

PMA- and ANG II-induced PKC regulation of the renal Na+-HCO3- cotransporter (hkNBCe1).

The renal electrogenic Na(+)-HCO3- cotransporter (hkNBCe1) plays a major role in the bicarbonate reabsorption by the kidney. We examined how PMA- and ANG II-activated PKCs regulate hkNBCe1 expressed with or without the ANG II receptors AT(1B) in Xenopus laevis oocytes. We found that 10 nM PMA halved the hkNBCe1 current detected in voltage-clamped oocytes.

Side chain orientation of residues lining the selectivity filter of epithelial Na+ channels.

Epithelial Na(+) channels (ENaCs) selectively conduct Na(+) and Li(+) but exclude K(+). A three-residue tract ((G/S)XS) present within all three subunits has been identified as a key structure forming a putative selectivity filter. We investigated the side chain orientation of residues within this tract by analyzing accessibility of the introduced sulfhydryl groups to thiophilic Cd(2+).