SC1/PRDM4 recruits PRMT5 to control the timing of neural precursor differentiation in developing neural stem cells

During cortical development, neural stem cells (NSCs) switch from proliferative to neuron-generating asymmetric divisions. Here we investigated the role of Schwann cell factor 1 (SC1/PRDM4), a transcriptional repressor highly expressed in the developing nervous system, during NSCs development. We found that SC1 protein levels were down-regulated in newly differentiating neurons, while remaining high in undifferentiated NSCs, suggesting an asymmetric inheritance of SC1. Knockdown of SC1 in the NSCs led to precocious differentiation of neurons and its overexpression led to an increase in Nestin-expressing precursors. We found that SC1, through its amino-terminus, recruits the chromatin modifier PRMT5, a histone arginine methyltransferase that catalyses histone H4R3 symmetric dimethylation (H4R3me2s). Mutations disrupting SC1/PRMT5 interaction resulted in loss of SC1-mediated increase in undifferentiated neural precursor cells. Our data demonstrate that SC1 and PRMT5 are components of an epigenetic regulatory complex that provides an epigenetic signature of a “stem-like” cellular state in the NSCs and which may be asymmetrically inherited during neurogenic divisions

Information flow and regulation of foraging activity in bumble bees (Bombus spp.)

Publisher version: http://www.apidologie.org

Dances as Windows into Insect Perception

Honeybees signal the location of food sources to their hive- mates using a "dancing" flight pattern. Translating these patterns, scientists learn what bees perceiv

Visual search and decision making in bees: time, speed and accuracy

An insect searching a meadow for flowers may detect several flowers from different species per second, so the task of choosing the right flowers rapidly is not trivial. Here we apply concepts from the field of visual search in human experimental psychology to the task a bee faces in searching a meadow for familiar flowers, and avoiding ‘‘distraction’’ by unknown or unrewarding flowers. Our approach highlights the importance of visual information processing for understanding the behavioral ecology of foraging. Intensity of illuminating light, target contrast with background (both chromatic and achromatic), and number of distractors are all shown to have a direct influence on decision times in behavioral choice experiments. To a considerable extent, the observed search behavior can be explained by the temporal and spatial properties of neuronal circuits underlying visual object detection. Our results also emphasize the importance of the time dimension in decision making. During visual search in humans, improved accuracy in solving discrimination tasks comes at a cost in response time, but the vast majority of studies on decision making in animals have focused on choice accuracy, not speed. We show that in behavioral choice experiments in bees, there is a tight link between the two. We demonstrate both between-individual and within- individual speed-accuracy tradeoffs, whereby bees exhibit considerable behavioral flexibility in solving visual search tasks. Motivation is an important factor in selection of behavioral strategies for a search task, and sensory discrimination capabilities may be underestimated by studies that quantify accuracy of behavioral choice but neglect the temporal dimension

Limits to the salience of ultraviolet: Lessons from colour vision in bees and birds

Publisher version: http://jeb.biologists.org/content/204/14/2571/F1.expansio